Ancylostoma caninum
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''Ancylostoma caninum'' is a species of
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
known as a
hookworm Hookworms are intestinal, blood-feeding, parasitic roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with poor access to adequate water, sanitation, an ...
, which principally infects the
small intestine The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the p ...
of
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s. The result of ''A. caninum'' infection ranges from
asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...
cases to death of the dog; better nourishment, increasing age, prior ''A. caninum'' exposure, or
vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...
are all linked to improved survival. Other
hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ( ...
include
carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...
s such as
wolves The wolf (''Canis lupus''; plural, : wolves), also known as the gray wolf or grey wolf, is a large Canis, canine native to Eurasia and North America. More than thirty subspecies of Canis lupus, subspecies of ''Canis lupus'' have been reco ...
,
fox Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush''). Twelve sp ...
es, and
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
s, with a small number of cases having been reported in humans. Warm and moist conditions are important to allow survival of ''A. caninum'' during the free-living stages of its lifecycle, so it is largely restricted to
temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
,
tropical 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
subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
regions. In parts of the world where these climatic requirements are met such as
Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
,
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...
, and
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
, ''A. caninum'' is the main cause of
hookworm disease Hookworm infection is an infection by a type of intestinal parasite known as a hookworm. Initially, itching and a rash may occur at the site of infection. Those only affected by a few worms may show no symptoms. Those infected by many worms may e ...
in
canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...
.


Morphology

''A. caninum'' females are typically long and wide, while the males are smaller at in length and in width. Males have
copulatory bursa
, which consists of spine-like
spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...
s positioned on three muscular rays that grasp the female during mating. As with other nematodes, the sperm lack
flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...
. The copulatory bursa is a unique feature of
Strongylida The Strongylida suborder includes many of the important nematodes found in the gastrointestinal tracts of ruminants, horses, and swine, as well as the lungworms of ruminants and the hookworms of dogs and cats. Taxonomy This suborder includes ( ...
members, thus making it a useful means for identifying members of this
suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
; it is also used to distinguish members within the suborder due to differences in bursa appearance between
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. The
vulva The vulva (plural: vulvas or vulvae; derived from Latin for wrapper or covering) consists of the external sex organ, female sex organs. The vulva includes the mons pubis (or mons veneris), labia majora, labia minora, clitoris, bulb of vestibu ...
of ''A. caninum'' females is located at the boundary of the second and final thirds of the body. The teeth of ''A. caninum'' are found in the buccal capsule and divided into three sets. Two
ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
sets form a lower-jaw equivalent, while a further set projects from the
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...
side and loosely equates to an upper jaw. Each ventral set has three points, with those furthest to the sides being the largest. While the ventral sets are prominent, the dorsal set is hidden deeper in the buccal capsule. ''A. caninum'' bends its head end upward (dorsally), which has been noted to be a potential source of confusion when determining how the hookworm is oriented. If it has recently ingested blood, ''A. caninum'' is red in colour; if not, it appears grey. ''A. caninum'' has an
alimentary canal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...
made up of an
esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
,
intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...
, and
rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
– the esophagus is highly muscular, reflecting its role in pulling
intestinal mucosa The gastrointestinal wall of the gastrointestinal tract is made up of four layers of specialised tissue. From the inner cavity of the gut (the lumen) outwards, these are: # Mucosa # Submucosa # Muscular layer # Serosa or adventitia The mucosa is ...
into the body when it feeds. Esophageal and anal rings of ''A. caninum'' are the source of
nerve fibres An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...
that extend throughout the body to innervate sensory organs, including amphids and phasmids.
Eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
are laid by the females, typically when at the
eight-cell stage In embryology, cleavage is the division of cells in the early development of the embryo, following fertilization. The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size ...
. Eggs are 38–43 μm in width, with thin walls.


Distribution

Freezing, temperatures exceeding , drying, or exposing ''A. caninum'' to sunlight all give reduced survival of the free-living stage, with rates of infection rising with temperature, provided 37°C is not exceeded. ''A. caninum'' is, therefore, largely restricted to warm, moist climates, though infections are seen in the United States and southern Canada where the temperature is suboptimal. Specific niches are also able to satisfy the environmental requirements of ''A. caninum'', despite not necessarily being in 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 ...
, such as mines.


Lifecycle


Transmission via the environment

Eggs are excreted from the host in the
feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
and typically hatch within a day on moist, warm soil into
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
with a non-living cuticle layer. By 4–5 days, the larvae have
moulted In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
twice and are now able to infect a host. Migration occurs from the feces into the surrounding
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
. Two routes of infection from the environment exist. The first route involves penetration of
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
at
hair follicles The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between h ...
or
sweat glands Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...
, especially between the
footpads ''Footpads'' is an 1895 British short silent drama film, directed by Robert W. Paul, featuring a top-hatted pedestrian against a rainy London backdrop, who is assaulted by three footpads and rescued by a passing policeman. The "atmospheric" f ...
where contact with soil is frequent and the skin is thinner than otherwise. Secretion of a
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 ...
by ''A. caninum'' is thought to aid this process. The larvae then migrate through the
dermis The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided i ...
of the skin, enter the
circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
and are carried to the
lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of th ...
. ''A. caninum'' larvae exit the blood at the lungs, move from the
alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * ...
up through the
trachea The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
and are swallowed to end up in the intestine. The second and more common route to the small intestine is by direct
ingestion Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms ingest ...
of ''A. caninum'' by the host, but the subsequent process is identical in either case. During this third stage of the larva, male or female reproductive organs become established. Larvae of this stage have been shown to secrete a molecule (Ac-asp-2) related to
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
allergens An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...
in response to host-specific signals; this is thought to have a possible role in helping with the infection process. A third and final moulting occurs, resulting in the mature form of ''A. caninum,'' which then feeds on mucosa and
blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
of the small intestinal wall. The trigger of feeding is understood to be a receptor-mediated response; however, the detail of this process has yet to be established. Sexual reproduction also occurs in the intestine to produce a further round of eggs to complete the cycle. Females are thought to produce a pheromone which attracts males and are able to lay about 10,000 eggs per day.


Direct transmission

Direct transmission between hosts is also possible. Larvae having accessed through the skin may avoid exit via the lungs and remain in circulation for transport around the body. At the
uterine artery The uterine artery is an artery that supplies blood to the uterus in females. Structure The uterine artery usually arises from the anterior division of the internal iliac artery. It travels to the uterus, crossing the ureter anteriorly, to the ute ...
of a pregnant female, the larvae are able to cross the
placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mater ...
to cause prenatal infection of foetuses. Larvae of an infected foetus move to 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 ...
until birth, when migration continues with movement to the intestine via the circulation and lungs as previously described. Alternatively, ''A. caninum'' larvae evading exit from the circulation at the lungs may instead be carried to the
mammary glands A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in prima ...
and transmitted from the mother in her
colostrum Colostrum, also known as beestings or first milk, is the first form of milk produced by the mammary glands of mammals (including humans) immediately following delivery of the newborn. Colostrum powder is rich in high protein and low in sugar and ...
or
milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digestion, digest solid food. Immune factors and immune ...
to her pups; infection then proceeds in an identical manner as infection by ingestion from the environment. Infected mothers have been found to only rarely give prenatal transmission to pups, while the likelihood of causing transmission via the lactational route during nursing is much higher.


Pathogenesis


Damage during migration to intestine

''A. caninum'' larvae cause damage to the host at the point of entry through the skin, leaving a wound vulnerable t
secondary infections
As the larvae migrate through the skin, an
inflammatory response Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecu ...
,
dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...
, is often stimulated, which can be exacerbated in hosts which have hypersensitive responses. Further damage is caused when the larvae leave the circulation and enter the lung, with the amount of damage dependent on the extent of the infection;
pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity ...
and
coughing 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 phas ...
are common consequences.


Damage once in intestine

Once in the gut, ''A. caninum'' attaches to and ingests the mucosal lining along with some consumption of blood; up to 0.1 ml in 24hrs. In a 24hr period ''A. caninum'' typically feeds from six sites. This damage to the mucosa compromises the body's defences and can result in secondary infections by
microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
. A group of
anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where the ...
proteins called ''A. caninum'' anticoagulant proteins (AcAPs), which inhibit a range of blood
coagulation factors Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...
such as Xa, are used by ''A. caninum'' to help in the feeding process by preventing clotting and increasing blood loss. These AcAPs are among the most powerful natural anticoagulants that exist and are a key reason for
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 ...
being caused and blood being observed in the faeces of infected hosts. Blood losses peak just prior to egg production by the females because this is when their requirements for food are greatest; the amount that they are eating is also peaking, so maximal damage to the intestine is being caused.


Diagnosis

Analysis of faeces is the definitive method by which a suspected ''A. caninum'' infection is confirmed. The faeces are sampled and examined microscopically for the characteristic ovular, thin-shelled eggs of ''A. caninum''. Absence of eggs in faeces does not rule out infection; a significant delay of at least 5 weeks exists between initial infection and excretion of eggs in the faeces (larvae must fully mature and reproduce before eggs can be laid). In fact, pups frequently die before passing of eggs in the faeces begins. Using the number of eggs in stool samples as an indicator of the extent of infestation requires care to be taken because females have been shown to produce fewer eggs when the overall number of worms increases. Signs and
symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an disease, illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormali ...
expected to be observed are
lethargy 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 ...
, weight loss, weakness, roughness of the hair coat, and pale
mucous membranes A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
indicative of anemia. Well-fed, older dogs with smaller infestations may present few or even none of these symptoms.
Diarrhoea 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 ...
is rare, but stools are typically black due to the blood-derived
haemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...
present in them. The disease resulting from such ''A. caninum'' infection is referred to by the general term "hookworm disease" or the more specific terms "
ancylostomiasis Ancylostomiasis is a hookworm disease caused by infection with Ancylostoma hookworms. The name is derived from Greek ancylos αγκύλος "crooked, bent" and stoma στόμα "mouth". Ancylostomiasis is also known as miner's anaemia, tunnel d ...
" and "ancylostomosis," which recognise the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of the causative nematode.


Prevention and control

A clean environment minimises the risk of ''A. caninum'' infection; this can include regularly washed
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
or
gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...
in
kennels A kennel is a structure or shelter for dogs. Used in the plural, ''the kennels'', the term means any building, collection of buildings or a property in which dogs are housed, maintained, and (though not in all cases) bred. A kennel can be made o ...
instead of soil. Females are typically checked prior to using them for
breeding Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant. Breeding may refer to: * Animal husbandry, through selected specimens such as dogs, horses, and rab ...
purposes for nematodes such as ''A. caninum'' and
birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
and
suckling Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that brea ...
can be restricted to sanitised areas to lower the risk of health complications to the pups. When infection of a pregnant dog is known or suspected
fenbendazole Fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: giardia, roundworms, hookworms, whipworms, the tapeworm genus '' Taenia'' (but not effective against ''Dipylidium caninum'', a common d ...
or
ivermectin Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...
can be administered to the female to help avoid transmission to the pups. Canines have been seen to develop significant resistance to ''A. caninum'' naturally with age; this protection develops faster in and fully mature females show substantially greater resistance than fully mature dogs. Specifically the age-related resistance means ''A. caninum'' takes longer to reach
sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...
in older animals and fewer larvae fully develop.


Vaccination

Numerous
vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...
s have been developed with varying success against ''A. caninum''. Use of an enzyme important in the worm's feeding process is popular, with one example being AcCP2, a protease, which, when used to vaccinate dogs, gives a strong
antibody response 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 ...
, a lowering of numbers of eggs found in stools and a decrease in intestinal worm size. These effects are attributed to reduced AcCP2 activity upon
antibody 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 ...
binding. A similar approach has been taken using another ''A. caninum'' digestive enzyme, AcGST1, but it failed to give statistically significant results in dogs. An alternative approach has been to disrupt the migratory ability of ''A. caninum;'' this was done successfully using the AcASP1 protein of ''A. caninum,'' which gives an increase in antibody levels of all subclasses, as well as a reduced worm burden. Other studies using the same vaccine have shown 79% reduction of worm burden resulting from this approach. Animals with prior exposure to ''A. caninum'' show enhanced resistance, but careful removal of all worms from the previous infection results in loss of this resistance. Studies in mice show resistance due to past exposure can protect against otherwise lethal worm doses and that this is a general form of resistance – defense is offered against subsequent infections via either mouth ''or'' skin.


Medication

Drugs used in treatment of ''A. caninum'' infections of dogs include:
dichlorvos Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, commonly abbreviated as an DDVP) is an organophosphate widely used as an insecticide to control household pests, in public health, and protecting stored products from insects. The compound has bee ...
,
fenbendazole Fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: giardia, roundworms, hookworms, whipworms, the tapeworm genus '' Taenia'' (but not effective against ''Dipylidium caninum'', a common d ...
,
flubendazole Flubendazole is an anthelmintic. Its brand name is Flutelmium which is a paste manufactured by Janssen Pharmaceutica N.V. used by veterinarians for protection against internal parasites and worms in dogs and cats. Other brand names are Flubenol, ...
,
mebendazole Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections, hydatid disease, ...
, nitroscanate,
piperazine Piperazine () is an organic compound that consists of a six-membered ring containing two nitrogen atoms at opposite positions in the ring. Piperazine exists as small alkaline deliquescent crystals with a saline taste. The piperazines are a broad ...
,
pyrantel Pyrantel is a medication used to treat a number of parasitic worm infections. This includes ascariasis, hookworm infections, enterobiasis (pinworm infection), trichostrongyliasis, and trichinellosis. It is taken by mouth. Side effects include ...
,
milbemycin The milbemycins are a group of macrolides chemically related to the avermectins and were first isolated in 1972 from '' Streptomyces hygroscopicus''. They are used in veterinary medicine as antiparasitic agents against worms, ticks and fleas.
,
moxidectin Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle and sheep. Moxidectin kills some of the most common internal and external ...
,
diethylcarbamazine Diethylcarbamazine is a medication used in the treatment of filariasis including lymphatic filariasis, tropical pulmonary eosinophilia, and loiasis. It may also be used for prevention of loiasis in those at high risk. While it has been used for o ...
,
oxibendazole Oxibendazole is a benzimidazole drug that is used to protect against roundworms, strongyles, threadworms, pinworms and lungworm infestations in horses and some domestic pets. It is usually white to yellowish in appearance, and may take the form ...
, and
ivermectin Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...
.


In humans

In inappropriate hosts such as humans, ''A. caninum'' is able to enter the skin, but cannot proceed into the circulation and on to the intestine; instead, the disease dermal larva migrans results, caused by movement of the nematode within the skin and which can persist for several months without intervention. While access to the intestine is not possible via this route, it can occur via ingestion; in a report of 93
enteritis Enteritis is inflammation of the small intestine. It is most commonly caused by food or drink contaminated with pathogenic microbes,Dugdale, David C., IIII, and George F Longretc"Enteritis" MedlinePlus Medical Encyclopedia, 18 October 2008. Access ...
cases in northern
Queensland, Australia ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...
, which were possibly caused by'' A. canium ''infection, all those interviewed described behaviour consistent with ''A. caninum'' exposure and a
colonoscopy Colonoscopy () or coloscopy () is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (''e. ...
of one patient gave positive identification of an adult ''A. caninum'' worm. Since then, work has shown ''A. caninum'' can easily go unnoticed or fail to be preserved in specimens, making the true incidence of infection in humans likely to be higher than is officially recorded.


Economic burden

The animals affected by ''A. caninum'' infection are not used for
food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
or labour purposes, thus the economic burden from
animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
illness is low. Human ''A. caninum'' infections are likely underestimated and misdiagnosed; the economic impact caused by missing work due to infection may be underestimated and significant.


References

{{Taxonbar, from=Q291499 Parasitic diseases Parasites of dogs Ancylostomatidae Nematodes described in 1859 Parasitic nematodes of mammals Parasites of cats