Fasciolosis is a
parasitic worm
Parasitic worms, also known as helminths, are large Parasitism#Basic concepts, macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted helminth, soil-transmitted and intestinal parasit ...
infection caused by the common liver fluke ''
Fasciola hepatica
''Fasciola hepatica'', also known as the common liver fluke or sheep liver fluke, is a parasitic trematode (fluke or flatworm, a type of helminth) of the class Trematoda, phylum Platyhelminthes. It infects the livers of various mammals, inc ...
'' as well as by ''
Fasciola gigantica
''Fasciola gigantica'' is a parasitic flatworm of the class Trematoda, which causes tropical fascioliasis. It is regarded as one of the most important single platyhelminth infections of ruminants in Asia and Africa. Estimates of infection rates ...
''. The disease is a plant-borne
trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host ...
zoonosis
A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...
,
and is classified as a
neglected tropical disease
Neglected tropical diseases (NTDs) are a diverse group of tropical disease, tropical infections that are common in low-income populations in Developing country, developing regions of Africa, Asia, and the Americas. They are caused by a variety ...
(NTD).
It affects humans, but its main host is ruminants such as cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
and sheep
Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
.[ The disease progresses through four distinct phases; an initial incubation phase of between a few days up to three months with little or no symptoms; an invasive or acute phase which may manifest with: fever, malaise, abdominal pain, gastrointestinal symptoms, urticaria, ]anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...
, jaundice
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
, and respiratory symptoms
Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bron ...
. The disease later progresses to a latent phase with less symptoms and ultimately into a chronic or obstructive phase months to years later. In the chronic state the disease causes inflammation of the bile duct
A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates.
Bile is required for the digestion of food and is secreted by the liver into passages that carry bile toward the hepatic duct. It ...
s, gall bladder
In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, althoug ...
and may cause gall stone
Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
s as well as fibrosis
Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
. While chronic inflammation is connected to increased cancer rates, it is unclear whether fasciolosis is associated with increased cancer risk.
Up to half of those infected display no symptoms,[ and diagnosis is difficult because the worm eggs are often missed in fecal examination.] The methods of detection are through fecal examination, parasite-specific antibody detection, or radiological diagnosis, as well as laparotomy
A laparotomy is a surgical procedure involving a surgical incision through the abdominal wall to gain access into the abdominal cavity. It is also known as a celiotomy.
Origins and history
The first successful laparotomy was performed without ane ...
. In case of a suspected outbreak it may be useful to keep track of dietary history, which is also useful for exclusion of differential diagnoses. Fecal examination is generally not helpful because the worm eggs can seldom be detected in the chronic phase of the infection. Eggs appear in the feces first between 9–11 weeks post-infection. The cause of this is unknown, and it is also difficult to distinguish between the different species of fasciola as well distinguishing them from echinostomes and ''Fasciolopsis
''Fasciolopsis'' () is a genus of trematodes. They are also known as giant intestinal flukes.
Only one species is recognised: ''Fasciolopsis buski''. It is a notable parasite of medical importance in humans and veterinary importance in pigs. I ...
''. Most immunodiagnostic tests detect infection with very high sensitivity, and as concentration drops after treatment, it is a very good diagnostic method. Clinically it is not possible to differentiate from other liver and bile diseases. Radiological methods can detect lesions in both acute and chronic infection, while laparotomy will detect lesions and also occasionally eggs and live worms.
Because of the size of the parasite, as adult ''F. hepatica'': or adult ''F. gigantica:'' , fasciolosis is a big concern. The amount of symptoms depend on how many worms and what stage the infection is in. The death rate is significant in both cattle (67.55%) and goats (24.61%), but generally low among humans. Treatment with triclabendazole
Triclabendazole, sold under the brand name Egaten among others, is a medication used to treat fascioliasis and paragonimiasis. It is very effective for both conditions. Treatment in hospital may be required. It is taken by mouth with typically ...
has been highly effective against the adult worms as well as various developing stages. Praziquantel
Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of helminthiasis, parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is us ...
is not effective, and older drugs such as bithionol
Bithionol is an antibacterial, anthelmintic, and algaecide. It is used to treat '' Anoplocephala perfoliata'' (tapeworms) in horses and ''Fasciola hepatica'' (liver flukes).
__TOC__ Mechanism of action
Bithionol has been shown to be a potent in ...
are moderately effective but also cause more side effects. Secondary bacterial infection causing cholangitis has also been a concern and can be treated with antibiotics, and toxaemia may be treated with prednisolone
Prednisolone is a steroid medication used to treat certain types of allergies, inflammatory conditions, autoimmune disorders, and cancers. Some of these conditions include adrenocortical insufficiency, high blood calcium, rheumatoid arthrit ...
.
Humans are infected by eating watergrown plants, primarily wild-grown watercress
Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae.
Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf ve ...
in Europe or morning glory
Morning glory (also written as morning-glory) is the common name for over 1,000 species of flowering plants in the family Convolvulaceae, whose current taxonomy and systematics are in flux. Morning glory species belong to many genera, some of ...
in Asia. Infection may also occur by drinking contaminated water with floating young fasciola or when using utensils washed with contaminated water. Cultivated plants do not spread the disease in the same capacity. Human infection is rare, even if the infection rate is high among animals. Especially high rates of human infection have been found in Bolivia, Peru and Egypt, and this may be due to consumption of certain foods. No vaccine is available to protect people against ''Fasciola'' infection. Preventative measures are primarily treating and immunization of the livestock, which are required to host the live cycle of the worms. Veterinary vaccines are in development, and their use is being considered by a number of countries on account of the risk to human health and economic losses resulting from livestock infection. Other methods include using molluscicide
Molluscicides () – also known as snail baits, snail pellets, or slug pellets – are pesticides against molluscs, which are usually used in agriculture or gardening, in order to control gastropod pests specifically slugs and snails which damag ...
s to decrease the number of snails that act as vectors, but it is not practical. Educational methods to decrease consumption of wild watercress and other waterplants has been shown to work in areas with a high disease burden.
Fascioliasis occurs in Europe, Africa, the Americas as well as Oceania. Recently, worldwide losses in animal productivity due to fasciolosis were conservatively estimated at over US$3.2 billion per annum. Fasciolosis is now recognized as an emerging human disease: the World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
(WHO) has estimated that 2.4 million people are infected with ''Fasciola'', and a further 180 million are at risk of infection.
Signs and symptoms
Humans
The course of fasciolosis in humans has 4 main phases:
* Incubation phase: from the ingestion of metacercariae to the appearance of the first symptoms; time period: few days to 3 months; depends on number of ingested metacercariae and immune status of host
* Invasive or acute phase: fluke migration up to the bile ducts. This phase is a result of mechanical destruction of the hepatic tissue and the peritoneum
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...
by migrating juvenile flukes causing localized and or generalized toxic and allergic
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...
reactions. The major symptoms of this phase are:
** Fever: usually the first symptom of the disease;
** Abdominal pain
** Gastrointestinal disturbances: loss of appetite, flatulence
Flatulence, in humans, is the expulsion of gas from the intestines via the anus, commonly referred to as farting. "Flatus" is the medical word for gas generated in the stomach or bowels. A proportion of intestinal gas may be swallowed environm ...
, nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
, diarrhea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
** Urticaria
Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and does not leave any long-lasti ...
** Respiratory symptoms (very rare): cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three pha ...
, dyspnoea
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...
, chest pain, hemoptysis
Hemoptysis is the coughing up of blood or blood-stained mucus from the bronchi, larynx, trachea, or lungs. In other words, it is the airway bleeding. This can occur with lung cancer, infections such as tuberculosis, bronchitis, or pneumonia, and ...
** Hepatomegaly
Hepatomegaly is the condition of having an enlarged liver. It is a non-specific medical sign having many causes, which can broadly be broken down into infection, hepatic tumours, or metabolic disorder. Often, hepatomegaly will present as an abdomi ...
and splenomegaly
Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant (LUQ) of the human abdomen. Splenomegaly is one of the four cardinal signs of ''hypersplenism'' which include: some reduction in number of circulating ...
** Ascites
Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...
** Anaemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...
** Jaundice
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
* Latent phase: This phase can last for months or years. The proportion of asymptomatic subjects in this phase is unknown. They are often discovered during family screening after a patient is diagnosed.
* Chronic or obstructive phase:
This phase may develop months or years after initial infection. Adult flukes in the bile ducts cause inflammation and hyperplasia of the epithelium. The resulting cholangitis and cholecystitis, combined with the large body of the flukes, are sufficient to cause mechanical obstruction of the biliary duct. In this phase, biliary colic
Colic or cholic () is a form of pain that starts and stops abruptly. It occurs due to muscular contractions of a hollow tube ( small and large intestine, gall bladder, ureter, etc.) in an attempt to relieve an obstruction by forcing content out ...
, epigastric
In anatomy, the epigastrium (or epigastric region) is the upper central region of the abdomen. It is located between the costal margins and the subcostal plane. Pain may be referred to the epigastrium from damage to structures derived from the fo ...
pain, fatty food intolerance, nausea, jaundice, pruritus
Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasant ...
, right upper-quadrant abdominal tenderness, etc., are clinical manifestations indistinguishable from cholangitis, cholecystitis
Cholecystitis is inflammation of the gallbladder. Symptoms include right upper abdominal pain, pain in the right shoulder, nausea, vomiting, and occasionally fever. Often gallbladder attacks (biliary colic) precede acute cholecystitis. The pain l ...
and cholelithiasis
A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of migr ...
of other origins. Hepatic enlargement may be associated with an enlarged spleen
The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes . or ascites. In case of obstruction, the gall bladder is usually enlarged and edema
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...
tous with thickening of the wall (Ref: Hepatobiliary Fascioliasis:
Sonographic and CT Findings in 87 Patients During the InitialPhase and Long-Term Follow-Up. Adnan Kabaalioglu, Kagan Ceken, Emel Alimoglu, Rabin Saba, Metin Cubuk, Gokhan Arslan, Ali Apaydin. AJR 2007; 189:824–828). Fibrous adhesions of the gall bladder to adjacent organs are common. Lithiasis
A calculus (plural calculi), often called a stone, is a concretion of material, usually mineral salts, that forms in an organ or duct of the body. Formation of calculi is known as lithiasis (). Stones can cause a number of medical conditions.
So ...
of the bile duct or gall bladder is frequent and the stones are usually small and multiple.
Other animals
Veterinary clinical signs of fasciolosis are always closely associated with infectious dose (amount of ingested metacercariae). In sheep, as the most common definitive host, clinical presentation is divided into 4 types:[
* Acute Type I Fasciolosis: infectious dose is more than 5000 ingested metacercariae. Sheep suddenly die without any previous clinical signs. ]Ascites
Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...
, abdominal
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
haemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagi ...
, icterus, pallor
Pallor is a pale color of the skin that can be caused by illness, emotional shock or stress, stimulant use, or anemia, and is the result of a reduced amount of oxyhaemoglobin and may also be visible as pallor of the conjunctivae of the eyes o ...
of membranes, weakness may be observed in sheep.
* Acute Type II Fasciolosis: infectious dose is 1000-5,000 ingested metacercariae. As above, sheep die but briefly show pallor, loss of condition and ascites
Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...
.
* Subacute Fasciolosis: infectious dose is 800-1000 ingested metacercariae. Sheep are lethargic
Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overwo ...
, anemic and may die. Weight loss is dominant feature.
* Chronic Fasciolosis: infectious dose is 200-800 ingested metacercariae. Asymptomatic or gradual development of bottle jaw and ascites (ventral edema
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...
), emaciation, weight loss.
In blood, anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...
, hypoalbuminemia
Hypoalbuminemia (or hypoalbuminaemia) is a medical sign in which the level of albumin in the blood is low. This can be due to decreased production in the liver, increased loss in the gastrointestinal tract or kidneys, increased use in the body, or ...
, and eosinophilia
Eosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds . Hypereosinophilia is an elevation in an individual's circulating blood eosinophil count above 1.5 x 109/ L (i.e. 1,500/μL). The hypereosinophilic syndro ...
may be observed in all types of fasciolosis.[ Elevation of ]liver enzyme
Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin ti ...
activities, such a glutamate dehydrogenase
Glutamate dehydrogenase (GLDH, GDH) is an enzyme observed in both prokaryotes and eukaryotic mitochondria. The aforementioned reaction also yields ammonia, which in eukaryotes is canonically processed as a substrate in the urea cycle. Typical ...
(GLDH), gamma-glutamyl transferase
Gamma-glutamyltransferase (also γ-glutamyltransferase, GGT, gamma-GT, gamma-glutamyl transpeptidase; ) is a transferase (a type of enzyme) that catalyzes the transfer of gamma-glutamyl functional groups from molecules such as glutathione to ...
(GGT), and lactate dehydrogenase
Lactate dehydrogenase (LDH or LD) is an enzyme found in nearly all living cells. LDH catalyzes the conversion of lactate to pyruvate and back, as it converts NAD+ to NADH and back. A dehydrogenase is an enzyme that transfers a hydride from on ...
(LDH), is detected in subacute or chronic fasciolosis from 12 to 15 weeks after ingestion of metacercariae. Economical effect of fasciolosis in sheep consists in sudden deaths of animals as well as in reduction of weight gain and wool production. In goats and cattle, the clinical manifestation is similar to sheep. However, acquired resistance to ''F. hepatica'' infection is well known in adult cattle. Calves are susceptible to disease but in excess of 1000 metacercariae are usually required to cause clinical fasciolosis. In this case the disease is similar to sheep and is characterized by weight loss, anemia, hypoalbuminemia and (after infection with 10,000 metacercariae) death.[ Importance of cattle fasciolosis consist in economic losses caused by condemnation of livers at slaughter and production losses especially due to reduced weight gain.
In sheep and sometimes cattle, the damaged liver tissue may become infected by the '']Clostridium
''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative ag ...
'' bacteria ''C. novyi'' type B. The bacteria will release toxins into the bloodstream resulting in what is known as black disease
Infectious necrotic hepatitis is a disease of large animals, especially sheep, caused by ''Clostridium novyi'' infection. The primary infection is intestinal and transferred by the faecal-oral route. Spores of ''C. novyi'' escape from the gut ...
. There is no cure and death follows quickly. As ''C. novyi'' is common in the environment, black disease is found wherever populations of liver flukes and sheep overlap.[Merck Veterinary Manual - Infectious Necrotic Hepatitis]
/ref>
Cause
Fasciolosis is caused by two digenetic
Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms (known as ''flukes'') with a syncytial tegument and, usually, two suckers, one ventral and one oral ...
trematodes ''F. hepatica'' and ''F. gigantica''. Adult flukes of both species are localized in the bile duct
A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates.
Bile is required for the digestion of food and is secreted by the liver into passages that carry bile toward the hepatic duct. It ...
s of the liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
or gallbladder
In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...
. ''F. hepatica'' measures 2 to 3 cm and has a cosmopolitan distribution
In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...
. ''F. gigantica'' measures 4 to 10 cm in length and the distribution of the species is limited to the tropics
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and has been recorded in Africa, the Middle East, Eastern Europe and south and eastern Asia. In domestic livestock in Japan, diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
(2n = 20), triploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...
(3n = 30) and chimeric flukes (2n/3n) have been described, many of which reproduce parthenogenetically
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...
. As a result of this unclear classification, flukes in Japan are normally referred to as ''Fasciola'' spp. Recent reports based on mitochondrial genes
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
analysis has shown that Japanese ''Fasciola'' spp. is more closely related to ''F. gigantica'' than to ''F. hepatica''. In India, a species called ''F. jacksoni'' was described in elephant
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae an ...
s.
Transmission
Human ''F. hepatica'' infection is determined by the presence of the intermediate snail hosts, domestic herbivorous animals, climatic conditions and the dietary habits of man.[ Sheep, goats and cattle are considered the predominant animal ]reservoir
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation.
Reservoirs can be created in a number of ways, including contro ...
s. While other animals can be infected, they are usually not very important for human disease transmission. On the other hand, some authors have observed that donkey
The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a ...
s and pigs contribute to disease transmission in Bolivia. Among wild animals, it has been demonstrated that the peridomestic rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...
(''Rattus rattus'') may play an important role in the spread as well as in the transmission of the parasite in Corsica
Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...
. In France, nutria
The nutria (''Myocastor coypus''), also known as the coypu, is a large, herbivorous, semiaquatic rodent.
Classified for a long time as the only member of the family Myocastoridae, ''Myocastor'' is now included within Echimyidae, the family of t ...
(''Myocastor coypus'') was confirmed as a wild reservoir host of ''F. hepatica''. Humans are infected by ingestion of aquatic plants that contain the infectious cercariae
Trematodes are parasitic flatworms of the class ''Trematoda'', specifically parasitic flukes with two suckers: one ventral and the other oral. Trematodes are covered by a tegument, that protects the organism from the environment by providing secr ...
. Several species of aquatic vegetables are known as a vehicle of human infection. In Europe, ''Nasturtium officinale
Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae.
Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf ve ...
'' (common watercress), '' Nasturtium sylvestre'', ''Rorippa amphibia
''Rorippa amphibia'' is a plant species in the genus ''Rorippa''. It is called great yellowcress. The flowers are visited by many types of insects, and can be characterized by a generalized pollination syndrome.
References
amphibia
...
'' (wild watercress), ''Taraxacum dens leonis'' (dandelion
''Taraxacum'' () is a large genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia and Nor ...
leaves), '' Valerianella olitoria'' (lamb's lettuce), and ''Mentha viridis'' (spearmint
Spearmint, also known as garden mint, common mint, lamb mint and mackerel mint, is a species of mint, ''Mentha spicata'' (, native to Europe and southern temperate Asia, extending from Ireland in the west to southern China in the east. It is nat ...
) were reported as a source of human infections. In the Northern Bolivian Altiplano, some authors suggested that several aquatic plants such as bero-bero (watercress), algas (algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
), kjosco and tortora could act as a source of infection for humans. Because ''F. hepatica'' cercaria
A cercaria (plural cercariae) is the larval form of the trematode class of parasites. It develops within the germinal cells of the sporocyst or redia. A cercaria has a tapering head with large penetration glands. It may or may not have a long sw ...
e also encyst on water surface, humans can be infected by drinking of fresh untreated water containing cercariae.[ In addition, an experimental study suggested that humans consuming raw liver dishes from fresh livers infected with juvenile flukes could become infected.
]
Intermediate hosts
Intermediate hosts of ''F. hepatica'' are freshwater snails from family Lymnaeidae
Lymnaeidae, common name the pond snails, is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila.
Lymnaeidae is the only family within the superfamily ...
.[ Snails from family ]Planorbidae
Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod molluscs. Unlike most molluscs, the blood of ram's horn snails contains iron-based hemoglobin ins ...
act as an intermediate host of ''F. hepatica'' very occasionally.
Mechanism
The development of infection in definitive host is divided into two phases: the parenchymal (migratory) phase and the biliary phase.[Dubinský, P., 1993. Trematódy a trematodózy. In: Jurášek, V., Dubinský, P. a kolektív, Veterinárna parazitológia. Príroda a.s., Bratislava, 158–187. (in Slovakian)] The parenchymal phase begins when excysted juvenile flukes penetrate the intestinal wall. After the penetration of the intestine, flukes migrate within the abdominal cavity and penetrate the liver or other organs. ''F. hepatica'' has a strong predilection for the tissues of the liver.[Behm, C.A., Sangster, N.C., 1999. Pathology, pathophysiology and clinical aspects. In: Dalton, J.P. (Ed.), Fasciolosis. CAB International Publishing, Wallingford, pp. 185–224.] Occasionally, ectopic locations of flukes such as the lungs, diaphragm
Diaphragm may refer to:
Anatomy
* Thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen
* Pelvic diaphragm or pelvic floor, a pelvic structure
* Urogenital diaphragm or triangular ligament, a pelvic structure
Other
* Diap ...
, intestinal wall, kidneys, and subcutaneous tissue can occur.[ During the migration of flukes, tissues are mechanically destroyed and ]inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
appears around migratory tracks of flukes. The second phase (the biliary phase) begins when parasites enter the biliary duct
A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates.
Bile is required for the digestion of food and is secreted by the liver into passages that carry bile toward the hepatic duct. It ...
s of the liver. In biliary ducts, flukes mature, feed on blood, and produce eggs. Hypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J ...
of biliar ducts associated with obstruction of the lumen occurs as a result of tissue damage.
Resistance to infection
Mechanisms of resistance have been studied by several authors in different animal species. These studies may help to better understand the immune response
An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including viruses, bacteria, parasites, and fungi which could ...
to ''F. hepatica'' in host and are necessary in development of vaccine against the parasite. It has been established that cattle acquire resistance to challenge infection with ''F. hepatica'' and ''F. gigantica'' when they have been sensitized with primary patent or drug-abbreviated infection.[ Resistance to fasciolosis was also documented in rats. On the other hand, sheep and goats are not resistant to re-infection with ''F. hepatica''. However, there is evidence that two sheep breeds, in particular Indonesian thin tail sheep and ]Red maasai sheep
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
, are resistant to ''F. gigantica''.
Diagnosis
Most immunodiagnostic tests will detect infection and have a sensitivity above 90% during all stages of the diseases. In addition antibody concentration quickly drops post treatment and no antibodies are present one year after treatment, which makes it a very good diagnostic method. In humans, diagnosis of fasciolosis is usually achieved parasitologically by findings the fluke eggs in stool, and immunologically by ELISA
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...
and Western blot
The western blot (sometimes called the protein immunoblot), or western blotting, is a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract. Besides detect ...
. Coprological examinations of stool alone are generally not adequate because infected humans have important clinical presentations long before eggs are found in the stools.
Moreover, in many human infections, the fluke eggs are often not found in the faeces, even after multiple faecal examinations. Furthermore, eggs of ''F. hepatica'', ''F. gigantica'' and ''Fasciolopsis buski'' are morphologically indistinguishable. Therefore, immunonological methods such ELISA and enzyme-linked immunoelectrotransfer blot, also called Western blot, are the most important methods in diagnosis of ''F. hepatica'' infection. These immunological tests are based on detection of species-specific antibodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
from sera. The antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
ic preparations used have been primarily derived from extracts of excretory/secretory products from adult worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete wor ...
s, or with partially purified fractions. Recently, purified native and recombinant antigens have been used, e.g. recombinant ''F. hepatica'' cathepsin L-like protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
.
Methods based on antigen detection (circulating in serum or in faeces) are less frequent. In addition, biochemical and haematological examinations of human sera support the exact diagnosis (eosinophilia, elevation of liver enzymes). Ultrasonography
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...
and xray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30  ...
of the abdominal cavity, biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
of liver, and gallbladder punctuate can also be used (ref: US-guided gallbladder aspiration:
a new diagnostic method for biliary fascioliasis. A. Kabaalioglu, A. Apaydin, T. Sindel, E. Lüleci. Eur. Radiol. 9, 880±882 (1999) . False fasciolosis ( pseudofasciolosis) refers to the presence of eggs in the stool resulting not from an actual infection but from recent ingestion of infected livers containing eggs. This situation (with its potential for misdiagnosis) can be avoided by having the patient follow a liver-free diet
Diet may refer to:
Food
* Diet (nutrition), the sum of the food consumed by an organism or group
* Dieting, the deliberate selection of food to control body weight or nutrient intake
** Diet food, foods that aid in creating a diet for weight loss ...
several days before a repeat stool examination.
In animals, intravital diagnosis is based predominantly on faeces examinations and immunological methods. However, clinical signs, biochemical and haematological profile, season, climate conditions, epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population.
It is a cornerstone of public health, and shapes policy decisions and evidenc ...
situation, and examinations of snails must be considered. Similarly to humans, faeces examinations are not reliable. Moreover, the fluke eggs are detectable in faeces 8–12 weeks post-infection. In spite of that fact, faecal examination is still the only used diagnostic tool in some countries. While coprological diagnosis of fasciolosis is possible from 8- to 12-week post-infection (WPI), ''F. hepatica'' specific-antibodies are recognized using ELISA or Western blot after 2-4 week post-infection. Therefore, these methods provide early detection of the infection.
Prevention
In some areas special control programs are in place or have been planned. The types of control measures depend on the setting (such as epidemiologic, ecologic, and cultural factors). Strict control of the growth and sale of watercress and other edible water plants is important. Individual people can protect themselves by not eating raw watercress and other water plants, especially from endemic grazing areas. Travelers to areas with poor sanitation should avoid food and water that might be contaminated (tainted). Vegetables grown in fields, that might have been irrigated with polluted water, should be thoroughly cooked, as should viscera from potentially infected animals.
Treatment
Humans
Several drugs are effective for fascioliasis, both in humans and in domestic animals. The drug of choice in the treatment of fasciolosis is triclabendazole
Triclabendazole, sold under the brand name Egaten among others, is a medication used to treat fascioliasis and paragonimiasis. It is very effective for both conditions. Treatment in hospital may be required. It is taken by mouth with typically ...
, a member of the benzimidazole
Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and imidazole. It is a colorless solid.
Preparation
Benzimidazole is produced by condensation of o- ...
family of anthelmintics
Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may a ...
. The drug works by preventing the polymerization of the molecule tubulin
Tubulin in molecular biology can refer either to the tubulin protein superfamily of globular proteins, or one of the member proteins of that superfamily. α- and β-tubulins polymerize into microtubules, a major component of the eukaryotic cytoske ...
into the cytoskeletal structures, microtubule
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...
s. Resistance of ''F. hepatica'' to triclabendazole has been recorded in Australia in 1995 and Ireland in 1998.
Praziquantel
Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of helminthiasis, parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is us ...
treatment is ineffective. There are case reports of nitazoxanide
Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is ind ...
being successfully used in human fasciolosis treatment in Mexico. There are also reports of bithionol
Bithionol is an antibacterial, anthelmintic, and algaecide. It is used to treat '' Anoplocephala perfoliata'' (tapeworms) in horses and ''Fasciola hepatica'' (liver flukes).
__TOC__ Mechanism of action
Bithionol has been shown to be a potent in ...
being used successfully.
Nitazoxanide
Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is ind ...
has been found effective in trials, but is currently not recommended.
Domestic animals
Only clorsulon and albendazole
Albendazole (also known as albendazolum) is a broad-spectrum anthelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, h ...
are approved for use in the treatment of domestic animals in the United States, but the available flukicides used worldwide also include triclabendazole
Triclabendazole, sold under the brand name Egaten among others, is a medication used to treat fascioliasis and paragonimiasis. It is very effective for both conditions. Treatment in hospital may be required. It is taken by mouth with typically ...
, netobimin, closantel, rafoxanide
Rafoxanide is a salicylanilide used as an anthelmintic. It is most commonly used in ruminant animals to treat adult liver flukes of the species ''Fasciola hepatica'' and ''Fasciola gigantica
''Fasciola gigantica'' is a parasitic flatworm of t ...
, nitroxynil, and oxyclozanide
Oxyclozanide is a salicylanilide anthelmintic. It is used in the treatment and control of fascioliasis in ruminants mainly domestic animals such as cattle, sheep, and goats. It mainly acts by uncoupling of oxidative phosphorylation in flukes. Alon ...
; however, this list of available drugs has some drawbacks.[Ballweber, L. (2018). Fasciola hepatica in ruminants. Merck vet manual (1.2)] Closantel, nitroxynil, and oxyclozanide are not effective against young liver flukes and should only be used to treat subacute and chronic infections. Triclabendazole is effective at killing flukes of any age, but only those that cause acute infections; flukes that have remained in the body for long periods of time are becoming resistant to this drug. The timing of treatment is critical for success, and is determined by environmental factors and analysis of the expected distribution and prevalence of the disease. For example, in European countries that have large numbers of sheep, computerized systems predict when fascioliasis is most likely to make the biggest impact on sheep populations and how many sheep will most likely be affected. The predictions are dependent on guessing when environmental conditions that are most conducive to parasite multiplication will occur, such as amount of rainfall, evapotranspiration, and the ratio of wet to dry days in a particular month. If heavy infections are expected to occur, treatment for sheep should begin in September/October, then again in January/February, and finally in April/May; the amount of hatching fluke eggs is minimal during these times because they require a warm, wet environment, making treatment more effective.
Epidemiology
Human and animal fasciolosis occurs worldwide.[ While animal fasciolosis is distributed in countries with high cattle and sheep production, human fasciolosis occurs, excepting Western Europe, in developing countries. Fasciolosis occurs only in areas where suitable conditions for intermediate hosts exist.
Studies carried out in recent years have shown human fasciolosis to be an important ]public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
problem.[Chen, M.G., Mott, K.E., 1990. "Progress in assessment of morbidity due to Fasciola hepatica infection: a review of recent literature". Trop. Dis. Bull. 87, R1–R38.] Human fasciolosis has been reported from countries in Europe, America, Asia, Africa and Oceania. The incidence of human cases has been increasing in 51 countries of the five continents. A global analysis shows that the expected correlation between animal and human fasciolosis only appears at a basic level. High prevalences in humans are not necessarily found in areas where fasciolosis is a great veterinary problem. For instance, in South America, hyperendemics and mesoendemics are found in Bolivia and Peru where the veterinary problem is less important, while in countries such as Uruguay, Argentina and Chile, human fasciolosis is only sporadic or hypoendemic.[
]
Europe
In Europe, human fasciolosis occur mainly in France, Spain, Portugal, and the former USSR.[ France is considered an important human endemic area. A total of 5863 cases of human fasciolosis were recorded from nine French hospitals from 1970 to 1982. Concerning the former Soviet Union, almost all reported cases were from the Tajik Republic.][ Several papers referred to human fasciolosis in Turkey. Recently, ]serological survey
Serology is the scientific study of Serum (blood), serum and other body fluids. In practice, the term usually refers to the medical diagnosis, diagnostic identification of Antibody, antibodies in the serum. Such antibodies are typically formed in r ...
of human fasciolosis was performed in some parts of Turkey. The prevalence of the disease was serologically found to be 3.01% in Antalya Province
Antalya Province ( tr, ) is located on the Mediterranean coast of south-west Turkey, between the Taurus Mountains and the Mediterranean Sea.
Antalya Province is the centre of Turkey's tourism industry, attracting 30% of foreign tourists visit ...
, and between 0.9 and 6.1% in Isparta Province
Isparta Province ( tr, ) is a province in southwestern Turkey. Its adjacent provinces are Afyon to the northwest, Burdur to the southwest, Antalya to the south, and Konya to the east. It has an area of 8,993 km2 and a population of 448,298 ...
, Mediterranean region of Turkey. In other European countries, fasciolosis is sporadic and the occurrence of the disease is usually combined with travelling to endemic areas.
Americas
In North America, the disease is very sporadic. In Mexico, 53 cases have been reported. In Central America, fasciolosis is a human health problem in the Caribbean islands, especially in zones of Puerto Rico and Cuba. Pinar del Río Province
Pinar del Río is one of the provinces of Cuba. It is at the western end of the island of Cuba.
Geography
The Pinar del Río province is Cuba's westernmost province and contains one of Cuba's three main mountain ranges, the Cordillera de Guanig ...
and Villa Clara Province
Villa Clara is one of the provinces of Cuba. It is located in the central region of the island bordering with the Atlantic at north, Matanzas Province by west, Sancti Spiritus Province by east, and Cienfuegos Province on the South. Villa Clara ...
are Cuban regions where fasciolosis was hyperendemic. In South America, human fasciolosis is a serious problem in Bolivia, Peru, and Ecuador. These Andean
The Andes, Andes Mountains or Andean Mountains (; ) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range i ...
countries are considered to be the area with the highest prevalence of human fasciolosis in the world. Well-known human hyperendemic areas are localized predominately in the high plain called altiplano
The Altiplano (Spanish for "high plain"), Collao (Quechua and Aymara: Qullaw, meaning "place of the Qulla") or Andean Plateau, in west-central South America, is the most extensive high plateau on Earth outside Tibet. The plateau is located at the ...
. In the Northern Bolivian Altiplano, prevalences detected in some communities were up to 72% and 100% in coprological and serological
Serology is the scientific study of serum and other body fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection (against a given mi ...
surveys, respectively. In Peru, ''F. hepatica'' in humans occurs throughout the country. The highest prevalences were reported in Arequipa
Arequipa (; Aymara and qu, Ariqipa) is a city and capital of province and the eponymous department of Peru. It is the seat of the Constitutional Court of Peru and often dubbed the "legal capital of Peru". It is the second most populated city ...
, Mantaro Valley
The Mantaro Valley, also known as Jauja Valley, is a fluvial inter-Andean valley of Junin region, east of Lima, the capital of Peru. The Mantaro River flows through the fertile valley which produces potatoes, maize, and vegetables among othe ...
, Cajamarca
Cajamarca (), also known by the Quechua name, ''Kashamarka'', is the capital and largest city of the Cajamarca Region as well as an important cultural and commercial center in the northern Andes. It is located in the northern highlands of Peru ...
Valley, and Puno Region
Puno () is a department and region in southeastern Peru. It is the fifth largest department in Peru, after Cuzco, Madre de Dios, Ucayali, and Loreto. It is bordered by Bolivia on the east, the departments of Madre de Dios on the north, Cusco ...
. In other South American countries like Argentina, Uruguay, Brazil, Venezuela and Colombia, human fasciolosis appear to be sporadic, despite the high prevalences of fasciolosis in cattle.
Africa
In Africa, human cases of fasciolosis, except in northern parts, have not been frequently reported. The highest prevalence was recorded in Egypt where the disease is distributed in communities living in the Nile Delta
The Nile Delta ( ar, دلتا النيل, or simply , is the delta formed in Lower Egypt where the Nile River spreads out and drains into the Mediterranean Sea. It is one of the world's largest river deltas—from Alexandria in the west to Po ...
.
Asia
In Asia, the most human cases were reported in Iran, especially in Gīlān Province, on the Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
. It was mentioned that more than 10,000 human cases were detected in Iran. In eastern Asia, human fasciolosis appears to be sporadic. Few cases were documented in Japan, Koreas, Vietnam, and Thailand.
Australia and the Oceania
In Australia, human fasciolosis is very rare (only 12 cases documented). In New Zealand, ''F. hepatica'' has never been detected in humans.
Other animals
A number of drugs have been used in control fasciolosis in animals. Drugs differ in their efficacy, mode of action, price, and viability. Fasciolicides (drugs against Fasciola spp.) fall into five main chemical groups:
* Halogenate
In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, ...
d phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...
s: bithionol (Bitin), hexachlorophene (Bilevon), nitroxynil (Trodax)
* Salicylanilides
Salicylanilide is a chemical compound which is the amide of salicylic acid and aniline. It is classified as both a salicylamide and an anilide.
Derivatives of salicylanilide have a variety of pharmacological uses. Chlorinated derivatives inclu ...
: closantel (Flukiver, Supaverm), rafoxanide (Flukanide, Ranizole)
* Benzimidazoles
Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and imidazole. It is a colorless solid.
Preparation
Benzimidazole is produced by condensation of o- ...
: triclabendazole (Fasinex), albendazole
Albendazole (also known as albendazolum) is a broad-spectrum anthelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, h ...
(Vermitan, Valbazen), mebendazol (Telmin), luxabendazole (Fluxacur)
* Sulphonamides
In organic chemistry, the sulfonamide functional group (also spelled sulphonamide) is an organosulfur group with the structure . It consists of a sulfonyl group () connected to an amine group (). Relatively speaking this group is unreactive. B ...
: clorsulon (Ivomec Plus)
* Phenoxyalkanes: diamphenetide (Coriban)
Triclabendazole (Fasinex) is considered as the most common drug due to its high efficacy against adult as well as juvenile flukes. Triclabendazole is used in control of fasciolosis of livestock in many countries. Nevertheless, long-term veterinary use of triclabendazole has caused appearance of resistance in ''F. hepatica''. In animals, triclabendazole resistance was first described in Australia, later in Ireland and Scotland
Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...
and more recently in the Netherlands. Considering this fact, scientists have started to work on the development of new drug. Recently, a new fasciolicide was successfully tested in naturally and experimentally infected cattle in Mexico. This new drug is called 'Compound Alpha' and is chemically very similar to triclabendazole. Countries where fasciolosis in livestock was repeatedly reported:
* Europe: UK, Ireland, France, Portugal, Spain, Switzerland, Italy, Netherlands, Germany, Poland
* Asia: Turkey, Russia, Thailand, Iraq, Iran, China, Vietnam, India, Nepal, Japan, Korea, Philippines
* Africa: Kenya, Zimbabwe, Nigeria, Egypt, Gambia, Morocco
* Australia and the Oceania: Australia, New Zealand
* Americas: United States, Mexico, Cuba, Peru, Chile, Uruguay, Argentina, Jamaica, Brazil
On September 8, 2007, Veterinary officials in South Cotabato
South Cotabato ( hil, Bagatnan Cotabato; ceb, Habagatang Cotabato; Maguindanaon: ''Pagabagatan Kutawatu'', Jawi: ڤاڬابڬتن كوتاواتو; tl, Timog Cotabato), officially the Province of South Cotabato, is a province in the Philippine ...
, Philippines said that laboratory tests on samples from cows, carabao
The carabao ( es, Carabao; tgl, Kalabaw; ceb, Kabaw; ilo, Nuang) is a domestic swamp-type water buffalo (''Bubalus bubalis'') native to the Philippines. Carabaos were introduced to Guam from the Spanish Philippines in the 17th century. They ...
s, and horses in the province's 10 towns and lone city showed the level of infection at 89.5%, a sudden increase of positive cases among large livestock due to the erratic weather condition in the area. They must be treated forthwith to prevent complications with surra
Surra (from the Marathi ''sūra'', meaning the sound of heavy breathing through nostrils, of imitative origin) is a disease of vertebrate animals. The disease is caused by protozoan trypanosomes, specifically ''Trypanosoma evansi'', of severa ...
and hemorrhagic
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagi ...
septicemia
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
diseases. Surra already affected all barangays
A barangay (; abbreviated as Brgy. or Bgy.), historically referred to as barrio (abbreviated as Bo.), is the smallest administrative division in the Philippines and is the native Filipino term for a village, district, or ward. In metropolitan ...
of the Surallah
Surallah, officially the Municipality of Surallah ( Hiligaynon: ''Banwa sang Surallah''; mdh, Inged nu Surallah, Jawi: ايڠايد نو سور الله), is a 1st class municipality in the province of South Cotabato, Philippines. According to t ...
town.GMA NEWS.TV, Rise in animal liver fluke cases alarms South Cotabato
/ref>
See also
* Fasciolopsiasis
Fasciolopsiasis results from an infection by the trematode ''Fasciolopsis buski'', the largest intestinal fluke of humans (up to 7.5 cm in length).
Signs and symptoms
Most infections are light, almost asymptomatic. In heavy infections, sympto ...
* Clonorchiasis
Clonorchiasis is an infectious disease caused by the Chinese liver fluke (''Clonorchis sinensis'') and two related species.
Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system.
Sympt ...
* Fh8 - chemical produced by fasciolosis infection in the liver
References
External links
Fasciolosis Overview
at CDC
The Centers for Disease Control and Prevention (CDC) is the National public health institutes, national public health agency of the United States. It is a Federal agencies of the United States, United States federal agency, under the United S ...
Immunodiagnosis of fasciolosis in Bolivian Altiplano
{{Helminthiases
Helminthiases
Veterinary helminthology
Animal diseases
Tropical diseases