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''Taenia solium'', the pork tapeworm, belongs to the
cyclophyllid Tapeworms of the order Cyclophyllidea (the cyclophyllid cestodes) are the most important cestode parasites of humans and domesticated animals. All have multiple proglottid "segments", and all have four suckers on their scolices (heads), though ...
cestode Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
family
Taeniidae The Taeniidae are a family of tapeworms. It is the largest family representing the order Cyclophyllidea. It includes many species of medical and veterinary importance, as '' Taenia solium'' (pork tapeworm), '' Taenia saginata'' (beef tapeworm), ...
. It is found throughout the world and is most common in countries where
pork Pork is the culinary name for the meat of the domestic pig (''Sus domesticus''). It is the most commonly consumed meat worldwide, with evidence of pig husbandry dating back to 5000 BCE. Pork is eaten both freshly cooked and preserved; ...
is eaten. It is a
tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...
that uses humans as its
definitive host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...
and
pigs The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...
as the intermediate or secondary hosts. It is transmitted to pigs through
human feces Human feces (or faeces in British English) is the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has been further broken down by bacteria in the large intestine. It also contains b ...
that contain the parasite eggs and contaminate their fodder. Pigs ingest the
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 ...
, which develop into larvae, then into
oncosphere An oncosphere is the larval form of a tapeworm once it has been ingested by an intermediate host animal. The intermediate host must ingest the tapeworm's eggs either in food or water-- once this has happened, the eggs hatch and develop into onc ...
s, and ultimately into infective tapeworm cysts, called cysticercus. Humans acquire the cysts through consumption of uncooked or under-cooked pork and the cysts grow into an adult worms in 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 ...
. There are two forms of human infection. One is "primary hosting", called taeniasis, and is due to eating under-cooked pork that contains the cysts and results in adult worms in the intestines. This form generally is without symptoms; the infected person does not know they have tapeworms. This form is easily treated with anthelmintic medications which eliminate the tapeworm. The other form, "secondary hosting", called cysticercosis, is due to eating food, or drinking water, contaminated with faeces from someone infected by the adult worms, thus ingesting the tapeworm eggs, instead of the cysts. The eggs go on to develop
cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...
primarily in the muscles, and usually with no symptoms. However some people have obvious symptoms, the most harmful and chronic form of which is when the cysts form in the brain. Treatment of this form is more difficult but possible. The adult worm has a flat, ribbon-like body which is white and measures 2 to 3 metres long, or more. Its tiny attachment, the
scolex Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
, contains suckers and a
rostellum The rostellum is a projecting part of the column in Orchidaceae flowers, and separates the male androecium from the female gynoecium, commonly preventing self-fertilisation. In many orchids, such as ''Orchis mascula'', the pollinia or pollen masse ...
as organs of attachment that attach to the wall of 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 ...
. The main body, consists of a chain of segments known as
proglottids Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
. Each proglottid is a little more than a self-sustainable, very lightly ingestive, self-contained reproductive unit since tapeworms are
hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
s. Human primary hosting is best diagnosed by microscopy of eggs in faeces, often triggered by spotting shed segments. In secondary hosting, imaging techniques such as computed tomography and
nuclear magnetic resonance Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...
are often employed. Blood samples can also be tested using antibody reaction of
enzyme-linked immunosorbent assay 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 ...
. ''T. solium'' deeply affects developing countries, especially in rural settings where pigs roam free, as clinical manifestations are highly dependent on the number, size, and location of the parasites as well as the host's immune and inflammatory response.


Description

Adult ''T. solium ''is a
triploblastic Triploblasty is a condition of the gastrula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm. Germ cells are set aside in the embryo at the blastula stage, which are incorporated into the gonads during organogenes ...
acoelomate The coelom (or celom) is the main body cavity in most animals and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, it r ...
, having no body cavity. It is normally 2 to 3 m in length, but can become much larger, sometimes over 8 m long. It is white in colour and flattened into a ribbon-like body. The anterior end is a knob-like attachment organ (sometimes mistakenly-referred to as a "head") called a
scolex Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
, 1 mm in diameter. The scolex bears four radially arranged suckers that surround the rostellum. These are the organs of adhesive attachment to the intestinal wall of the host. The rostellum is armed with two rows of
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
aceous spiny hooks. Its 22 to 32 rostellar hooks can be differentiated into short (130 Âµm) and long (180 Âµm) types. After a short neck is the elongated body, the strobila. The entire body is covered by a covering called a tegument, which is an absorptive layer consisting of a mat of minute specialised
microvilli Microvilli (singular: microvillus) are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, ...
called
microtriches Microtriches (singular microtrix) are the highly specialized microvilli covering the entire surface of the tegument of cestodes. They are fine hair-like filaments distributed throughout the surface of the body, both unique to and ubiquitous among ...
. The strobila is divided into segments called proglottids, 800 to 900 in number. Body growth starts from the neck region, so the oldest proglottids are at the posterior end. Thus, the three distinct proglottids are immature proglottids towards the neck, mature proglottids in the middle, and
gravid In biology and human medicine, gravidity and parity are the number of times a woman is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with additional t ...
proglottids at the posterior end. A
hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separ ...
species, each mature proglottid contains a set of male and female reproductive systems. The numerous
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
and a bilobed
ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
open into a common genital pore. The oldest gravid proglottids are full of fertilised eggs, Each fertilised egg is spherical and measures 35 to 42 Âµm in diameter. If released early enough in the digestive tract and not passed, fertilised eggs can mature using upper tract digestive enzymes and the tiny larvae migrate to form cysticerci in humans. These have three morphologically distinct types. The common one is the ordinary "
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
" cysticercus, which has a fluid-filled
bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
0.5 to 1.5 cm in length and an invaginated
scolex Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
. The intermediate form has a scolex. The "racemose" has no evident scolex, but is believed to be larger. They can be 20 cm in length and have 60 ml of fluid, and 13% of patients with neurocysticercosis can have all three types in the brain. File:Taenia solium.jpg, ''Taenia solium'' adult File:Taenia solium scolex x400.jpg, ''Taenia solium'' scolex (x400) File:Taenia egg.jpg, Egg of ''T. solium''


Life cycle

The life cycle of ''T. solium'' is indirect as it passes through pigs, as intermediate hosts, into humans, as definitive hosts. In humans the infection can be relatively short or long lasting, and in the latter case if reaching the brain can last for life. From humans, the eggs are released in the environment where they await ingestion by another host. In the secondary host, the eggs develop into oncospheres which bore through the intestinal wall and migrate to other parts of the body where the cysticerci form. The cysticerci can survive for several years in the animal.


Definitive host

Humans are colonised by the larval stage, the cysticercus, from undercooked pork or other meat. Each microscopic cysticercus is oval in shape, containing an inverted scolex (specifically "protoscolex"), which everts once the organism is inside the small intestine. This process of
evagination Endodermic evagination relates to the inner germ layers of cells of the very early embryo, from which is formed the lining of the digestive tract, of other internal organs, and of certain glands, implies the extension of a layer of body tissue to f ...
is stimulated by bile juice and
digestive enzymes Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of anima ...
(of the host). Then, the protoscolex lodges in the host's upper intestine by using its crowned hooks and 4 suckers to enter the intestinal mucosa. Then, the scolex is fixed into the intestine by having the suckers attached to the villi and hooks extended. It grows in size using nutrients from the surroundings. Its strobila lengthens as new proglottids are formed at the foot of the neck. In 10–12 weeks after initial colonisation, it is an adult worm. The exact life span of an adult worm is not determined; however, evidences from an outbreak among British military in the 1930s indicate that they can survive for 2 to 5 years in humans. As a hermaphrodite, it reproduces by
self-fertilisation Autogamy, or self-fertilization, refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species of ...
, or
cross-fertilisation Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity. Outcrossing can be a useful ...
if
gametes A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...
are exchanged between two different proglottids.
Spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, ...
fuse with the
ova , abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and series made specially for release in home video formats without prior showings on television or in theaters, though the first part of an OVA s ...
in the fertilisation duct, where the
zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellula ...
s are produced. The zygote undergoes
holoblastic 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 ...
and unequal cleavage resulting in three cell types, small, medium and large (micromeres, mesomeres, megameres). Megameres develop into a syncytial layer, the outer embryonic membrane; mesomeres into the radially striated inner embryonic membrane or embryophore; micromeres become the
morula A morula (Latin, ''morus'': mulberry) is an early-stage embryo consisting of a solid ball of cells called blastomeres, contained in mammals, and other animals within the zona pellucida shell. The blastomeres are the daughter cells of the zygote ...
. The morula transforms into a six-hooked embryo known as an
oncosphere An oncosphere is the larval form of a tapeworm once it has been ingested by an intermediate host animal. The intermediate host must ingest the tapeworm's eggs either in food or water-- once this has happened, the eggs hatch and develop into onc ...
, or hexacanth ("six hooked") larva. A gravid proglottid can contain more than 50,000 embryonated eggs. Gravid proglottids often rupture in the intestine, liberating the oncospheres in faeces. Intact gravid proglottids are shed off in groups of four or five. The free eggs and detached proglottids are spread through the host's defecation (
peristalsis Peristalsis ( , ) is a radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which ...
). Oncospheres can survive in the environment for up to two months.


Intermediate host

Pigs are the principal intermediate hosts that ingest the eggs in traces of human faeces, mainly from vegetation contaminated with it such as from water bearing traces of it. The embryonated eggs enter intestine where they hatch into motile oncospheres. The embryonic and basement membranes are removed by the host's digestive enzymes (particularly
pepsin Pepsin is an endopeptidase that breaks down proteins into smaller peptides. It is produced in the gastric chief cells of the stomach lining and is one of the main digestive enzymes in the digestive systems of humans and many other animals, w ...
). Then the free oncospheres attach on the intestinal wall using their hooks. With the help of digestive enzymes from the penetration glands, they penetrate the
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 ...
to enter
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 ...
and
lymphatic vessels The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...
. They move along the general
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 ...
to various organs, and large numbers are cleared in 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 ...
. The surviving oncospheres preferentially migrate to striated muscles, as well as the
brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
, liver, and other tissues, where they settle to form
cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...
— cysticerci. A single cysticercus is spherical, measuring 1–2 cm in diameter, and contains an invaginated protoscolex. The central space is filled with fluid like a
bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
, hence it is also called bladder worm. Cysticerci are usually formed within 70 days and may continue to grow for a year. Humans are also accidental secondary hosts when they are colonised by embryonated eggs, either by auto-colonisation or ingestion of contaminated food. As in pigs, the oncospheres hatch and enter blood circulation. When they settle to form cysts, clinical symptoms of
cysticercosis Cysticercosis is a tissue infection caused by the cysticercus, young form of the Taenia solium, pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may ...
appear. The cysticercus is often called the metacestode.


Diseases


Signs and symptoms


Taeniasis

Taeniasis is infection in the intestines by the adult ''T. solium''. It generally has mild or
non-specific symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...
. This may include abdominal pain, nausea, diarrhoea and constipation. Such symptoms will arise when the tapeworm has fully developed in the intestine, this would be around eight weeks after the contraction (ingestion of meat containing cysticerci). These symptoms could continue until the tapeworm dies from the course of treatment but otherwise could continue for many years, as long as the worm lives. If untreated it is common that the infections with ''T. solium'' last for approximately 2–3 years. It is possible that infected people may show no symptoms for years.


Cysticercosis

Ingestion of ''T. solium'' eggs or egg-containing proglottids which rupture within the host intestines results in the development and subsequent migration of
larva 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 ...
e into host tissue to cause cysticercosis. In pigs, there are not normally pathological lesions as they easily develop immunity. But in humans, infection with the eggs causes serious medical conditions. This is because ''T. solium'' cysticerci have a predilection for the brain. In symptomatic cases, a wide spectrum of symptoms may be expressed, including headaches, dizziness, and seizures. Brain infection by the cysticerci is called neurocysticercosis and is the leading cause of seizures worldwide. In more severe cases,
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
or
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
can occur due to perturbation of the normal circulation of
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
. (Any increase in intracranial pressure will result in a corresponding increase in
arterial blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...
, as the body seeks to maintain circulation to the brain.) The severity of cysticercosis depends on location, size and number of parasite larvae in tissues, as well as the host
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 ...
. Other symptoms include sensory deficits, involuntary movements, and brain system dysfunction. In children,
ocular Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...
cysts are more common than in other parts of the body. In many cases, cysticercosis in the brain can lead to
epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...
,
seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or neural oscillation, synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much o ...
,
lesions A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...
in the brain,
blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment†...
,
tumour A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
-like growths, and low
eosinophil Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
levels. It is the cause of major neurological problems, such as
hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased intracranial pressure, pressure inside the skull. Older people may have headaches, double vision, poor ...
, paraplegy,
meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...
,
convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...
s, and even death.


Diagnosis

Stool test A stool test is a medical diagnostic technique that involves the collection and analysis of fecal matter. Microbial analysis (culturing), microscopy and chemical tests are among the tests performed on stool samples. Collection Stool samples shoul ...
s commonly include microbiology testing – the microscopic examination of stools after concentration aims to determine the amount of eggs. Specificity is extremely high for someone with training but sensitivity is quite low because the high variation in the number of eggs in small amounts of sample. Stool tapeworm antigen detection: Using
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 ...
increases the sensitivity of the diagnosis. The downside of this tool is it has high costs, an ELISA reader and reagents are required and trained operators are needed. A studies using Coproantigen (CoAg) ELISA methods are considered very sensitive but currently only genus specific. A 2020 study in Ag-ELISA test on Taenia solium cystercicosis in infected pigs and showed 82.7% sensitivity and 86.3% specificity. The study concluded that the test is more reliable in ruling out T. solium cystercosis versus confirmation. Stool PCR: This method can provide a species-specific diagnosis when proglottid material is taken from the stool. This method requires specific facilities, equipment and trained individuals to run the tests. This method has not yet been tested in controlled field trials. Serum antibody tests: using
immunoblot 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 ...
and ELISA, tape-worm specific circulating antibodies have been detected. The assays for these tests have both a high sensitivity and specificity. A 2018 study of two commercially available kits showed low sensitivity with patients diagnose with NCC (neurocysticercosis) especially with calcified NCC versus patients with cystic hydatid disease. Current standard for serologic diagnosis of NCC is the lentil lectin-bound glycoproteins/enzyme-linked immunoelectrotransfer blot (LLGP-EITB). Guidelines for diagnosis and treatment remain difficult for endemic countries, most of them developing with limited resources. Many developing countries diagnosed clinically with imaging.


Prevention

The best way to avoid getting tapeworms is to not eat undercooked pork or vegetables contaminated with faeces. Moreover, a high level of sanitation and prevention of faecal contamination of pig feeds also plays a major role in prevention. Infection can be prevented with proper disposal of human faeces around pigs, cooking meat thoroughly or freezing the meat at −10 Â°C for 5 days. For human cysticercosis, dirty hands are attributed to be the primary cause, and especially common among food handlers.


Treatment

Treatment of cysticercosis must be carefully monitored for inflammatory reactions to the dying worms, especially if they are located in the brain.
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 ...
is commonly given (along with
glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
s to reduce the inflammation). In selected cases, surgery may be required to remove the cysts. In neurocysticercosis, most patients under cysticidal therapy will have significant improvement in seizure control. A combination of
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 ...
and albendazole is more effective in treating neurocystercosis. A 2014 double blind randomized control study showed increased parasiticidal effect with albendazole plus praziquantel. A vaccine to prevent cysticercosis in pigs has been studied. The life-cycle of the parasite can be terminated in their intermediate host, pigs, thereby preventing further human infection. The large scale use of this vaccine, however, is still under consideration. During the 1940s, the preferred treatment was oleoresin of
aspidium ''Tectaria'' is a genus of fern in the family Tectariaceae, according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Halberd fern is a common name for species in this genus. Species , the ''Checklist of Ferns and Lycophyte ...
, which would be introduced into the duodenum via a Rehfuss tube.


Epidemiology

''T. solium'' is found worldwide, but its two distinctive forms rely on eating undercooked pork or on ingesting faeces-contaminated water or food (respectively). Because pig meat is the intermediate source of the intestinal parasite, rotation of the full
life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...
occurs in regions where humans live in close contact with pigs and eat undercooked pork. However, humans can also act as secondary hosts, which is a more pathological, harmful stage triggered by oral contamination. High prevalences are reported among many places with poorer than average water hygiene or even mildly contaminated water especially with a pork-eating heritage such as Latin America, West Africa, Russia, India, Manchuria, and Southeast Asia. In Europe it is most common in pockets of
Slavic countries Slavs are the largest European ethnolinguistic group. They speak the various Slavic languages, belonging to the larger Balto-Slavic branch of the Indo-European languages. Slavs are geographically distributed throughout northern Eurasia, main ...
and among global travelers taking inadequate precautions in eating pork especially. The secondary host form, human cysticercosis, predominates in areas where poor hygiene allows for mild fecal contamination of food, soil, or water supplies. Rates in the United States have shown immigrants from Mexico, Central and South America, and Southeast Asia bear the brunt of cases of cysticercosis caused by the ingestion of microscopic, long-lasting and hardy tapeworm eggs. Rates of ''T. solium'' cysticercosis in West Africa are not affected by any religion. For example, in 1990 and 1991 four unrelated members of an
Orthodox Jewish Orthodox Judaism is the collective term for the traditionalist and theologically conservative branches of contemporary Judaism. Theologically, it is chiefly defined by regarding the Torah, both Written and Oral, as revealed by God to Moses on M ...
community in
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developed recurrent seizures and brain lesions, which were found to have been caused by ''T. solium''. All had housekeepers from Mexico, some of whom were suspected to be the source of the infections. Neurocystiscercosis is noted at around one-third of all epilepsy cases in many developing countries. Neurological morbidity and mortality remain high in lower-income countries and high amongst developed countries with high rates of migration. Global prevalence rates remain largely unknown as screening tools, immunological, molecular tests, and neuroimaging are not usually available in many endemic areas.Carpio A, Fleury A, Romo ML, Abraham R. Neurocysticercosis: the good, the bad, and the missing. Expert Rev Neurother. 2018 Apr;18(4):289-301. doi: 10.1080/14737175.2018.1451328. Epub 2018 Mar 14. PMID 29521117.


See also

* List of parasites


References


External links


Taenia solium Genome Project - UNAM







''Taenia solium'' at Bioweb



ZicodeZoo

BioLib
{{Taxonbar, from=Q565708 Cestoda Foodborne illnesses Parasitic helminths of humans Parasitic animals of mammals Animals described in 1758 Neurological disorders Swine diseases Taxa named by Carl Linnaeus