Cysticercosis
Encyclopedia
Cysticercosis refers to tissue infection after exposure to eggs
of Taenia solium, the pork tapeworm. The disease is spread via the fecal-oral route
through contaminated food and water, and is primarily a food borne disease. After ingestion the eggs pass through the lumen
of the intestine into the tissues and migrate preferentially to the brain and muscles. There they form cysts that can persist for years.
In some cases the cysts will eventually cause an inflammatory reaction presenting as painful nodules in the muscles and seizures when the cysts are located in the brain. Symptomatic disease from Taenia solium cysts in the brain is referred to as neurocysticercosis and is the most common helmenthic (tapeworm) infection of the brain worldwide.
Cysticercosis should be differentiated from taeniasis
: carriage of the adult tapeworm in the intestine (which is through ingestion of cysts in an intermediate host, not the ingestion of the eggs as in cysticerosis). These represent two different stages of the parasite’s life cycle
. Though both forms of infection can potentially occur in the same individual at the same time, they are distinct disease entities and have different treatments and potential outcomes.
ians that date back to almost 2000 BC. The description of measled pork in the History of Animals
written by Aristotle
(384–322 BC) showed that the infection of pork with tapeworm was known to ancient Greeks
at that time. It was also known to Jewish
and later to early Muslim physicians and has been proposed as one of the reasons for pork being forbidden by Jewish
and Islamic dietary laws
. Recent examination of evolutionary histories of hosts and parasites and DNA evidence show that over 10,000 years ago, ancestors of modern humans in Africa became exposed to tapeworm when they scavenged for food or preyed on antelopes and bovids, and later passed the infection on to domestic animals such as pigs.
Cysticercosis was described by Johannes Udalric Rumler in 1555; however, the connection between tapeworms and cysticercosis had not been recognized at that time. Around 1850, Friedrich Küchenmeister
fed pork containing cysticerci of T. solium to humans awaiting execution in a prison, and after they had been executed, he recovered the developing and adult tapeworms in their intestines. By the middle of the 19th century, it was established that cysticercosis was caused by the ingestion of the eggs of T. solium.
The cysticercus larva completes development in about 2 months. It is semitransparent, opalescent white, and elongate oval in shape and may reach a length of 0.6 to 1.8 cm.
) per proglottid into the intestine. Nearly 250,000 ova are passed daily into the human feces and to the environment, and the cycle continues.
Infections with cysticercus occur after humans consume the ova from exogenous sources or through self-infection via the fecal-oral route. Humans, in this case, are intermediate hosts. Ova are digested in the stomach and release oncospheres which penetrate the intestinal wall and reach the bloodstream. These oncospheres develop into cysticerci in any organ but are common in brain, subcutaneous tissue, or eyes.
, with fever, eosinophilia
, and muscular pseudohypertrophy, which initiate with muscle swelling and later progress to atrophy and fibrosis. In most cases, it is asymptomatic since the cysticerci die and become calcified.
of the brain. It presents with seizures and, less commonly, headaches.
and present with symptoms of increased intracranial pressure
.
. These can occasionally grown into large lobulated masses causing pressure on surrounding structures.
.
In CDC’s immunoblot assay, cysticercosis-specific antibodies can react with structural glycoprotein antigens from the larval cysts of T. solium. However this is mainly a research tool not widely available in clinical practice and nearly unobtainable in resource limited settings.
The diagnosis of neurocysticercosis is mainly clinical, based on a compatible presentation of symptoms and findings of imaging studies. Neuroimaging with CT or MRI is the most useful method of diagnosis. CT scan shows both calcified and uncalcified cysts, as well as distinguishing active and inactive cysts. MRI is more sensitive in detection of intraventricular cysts.
medications. Once the seizures have been brought under control, antihelminthic treatments may be undertaken. The decision to treat with antiparasitic therapy is complex and based on the stage and number of cysts present, their location, and the patient's specific clinical presentation. Antiparasitic treatment should be given in combination with corticosteroids and anticonvulsants to reduce inflammation surrounding the cysts and lower the risk of seizures. Albendazole
is generally preferable over praziquantel
due to its lower cost and fewer drug interactions.
Asymptomatic cysts, such as those discovered incidentally on neuroimaging done for another reason, may never lead to symptomatic disease and in many cases do not require therapy.
Calcified cysts have already died and involuted. Further antiparasitic therapy will be of no benefit.
Surgical intervention is much more likely to be needed in cases of intraventricular, racemose, or spinal neurocysticercosis. Treatments includes direct excision of ventricular cysts, shunting procedures, and removal of cysts via endoscopy.
For example,
Non-infected pigs from rural villages in Mexico were vaccinated with S3Pvac and the vaccine reduced 98% the number of cysticerci and 50% the number of prevalence. The diagnostic method involves necropsy and tongue inspection of pigs. The natural challenge conditions used in the study proved the efficacy of the S3Pvac vaccine in transmission control of T. solium in Mexico. The S3Pvac vaccine is owned by the National Autonomous University of Mexico and the method of high scale production of the vaccine has already been developed. The validation of the vaccine in agreement with the Secretary of Animal Health in Mexico is currently in the process of completion. It is also hoped that the vaccine will be well-accepted by pig owners because they also lose their income if pigs are infected cysticercosis. Vaccination of pigs against cysticercosis, if succeeded, can potentially have a great impact on transmission control since there is no chance of re-infection once pigs receive vaccination.
Due to these limitations, cysticercosis has not been eliminated in any endemic areas.
to many parts of the world including China, Southeast Asia, India, sub-Saharan Africa, and Latin America. Some studies suggest that the prevalence of cysticercosis in Mexico is between 3.1 and 3.9 percent. Other studies have found the seroprevalence
in areas of Guatemala, Bolivia, and Peru as high as 20 percent in humans, and 37 percent in pigs. In Ethiopia, Kenya and the Democratic Republic of Congo around 10% of the population is infected, in Madagascar 16%. The frequency has decreased in developed countries owing to stricter meat inspection, better hygiene and better sanitary facilities. The distribution of cysticercosis coincides with the distribution of T. solium. Cysticercosis is the most common cause of symptomatic epilepsy
worldwide.
In Latin America, an estimated 75 million persons live in endemic areas and 400,000 people have symptomatic disease. Cysticercosis is also found to be associated with Hispanic ethnicity, immigrant status, and exposure to areas of endemicity. In the US, the disease is found in immigrants from Mexico, Central and South America. Current livestock for pigs in the U.S do not play a role in the transmission of Taenia solium, and thus cysticercosis in the U.S is an imported disease.
In the USA during 1990–2002, 221 cysticercosis deaths were identified. Mortality rates were highest for Latinos and men. The mean age at death was 40.5 years (range 2–88). Most patients, 84.6%, were foreign born, and 62% had emigrated from Mexico. The 33 US-born persons who died of cysticercosis represented 15% of all cysticercosis-related deaths. The cysticercosis mortality rate was highest in California, which accounted for ˜60% of all deaths.
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
of Taenia solium, the pork tapeworm. The disease is spread via the fecal-oral route
Fecal-oral route
The fecal-oral route, or alternatively, the oral-fecal route or orofecal route is a route of transmission of diseases, in which they are passed when pathogens in fecal particles from one host are introduced into the oral cavity of another potential host.There are usually intermediate steps,...
through contaminated food and water, and is primarily a food borne disease. After ingestion the eggs pass through the lumen
Lumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
of the intestine into the tissues and migrate preferentially to the brain and muscles. There they form cysts that can persist for years.
In some cases the cysts will eventually cause an inflammatory reaction presenting as painful nodules in the muscles and seizures when the cysts are located in the brain. Symptomatic disease from Taenia solium cysts in the brain is referred to as neurocysticercosis and is the most common helmenthic (tapeworm) infection of the brain worldwide.
Cysticercosis should be differentiated from taeniasis
Taeniasis
Taeniasis is a form of tapeworm infection which is caused by tapeworms of the genius Taenia.The two most important human pathogens in the genus are Taenia solium and Taenia saginata . Infection is acquired by eating undercooked contaminated meat. The adult worms live in the lumen of the intestine...
: carriage of the adult tapeworm in the intestine (which is through ingestion of cysts in an intermediate host, not the ingestion of the eggs as in cysticerosis). These represent two different stages of the parasite’s life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
. Though both forms of infection can potentially occur in the same individual at the same time, they are distinct disease entities and have different treatments and potential outcomes.
Agent
The cause of human cysticercosis is the larval form of Taenia solium (pork tapeworm). T. solium is a member of Phylum Platyhelminthes, class Cestoda, Order Cyclophyllidea and family Taeniidae. The common larval stage of T. solium was also known as Cysticercus cellulosae.History of discovery
The earliest reference to tapeworms were found in the works of ancient EgyptAncient Egypt
Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...
ians that date back to almost 2000 BC. The description of measled pork in the History of Animals
History of Animals
History of Animals is a zoological natural history text by Aristotle.-Arabic translation:The Arabic translation of Historia Animalium comprises treatises 1-10 of the Kitāb al-Hayawān .-See also:...
written by Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
(384–322 BC) showed that the infection of pork with tapeworm was known to ancient Greeks
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...
at that time. It was also known to Jewish
and later to early Muslim physicians and has been proposed as one of the reasons for pork being forbidden by Jewish
Kashrut
Kashrut is the set of Jewish dietary laws. Food in accord with halakha is termed kosher in English, from the Ashkenazi pronunciation of the Hebrew term kashér , meaning "fit" Kashrut (also kashruth or kashrus) is the set of Jewish dietary laws. Food in accord with halakha (Jewish law) is termed...
and Islamic dietary laws
Islamic dietary laws
Islamic dietary laws provide direction on what is to be considered clean and unclean regarding diet and related issues.-Overview:Islamic jurisprudence specifies which foods are ' and which are '...
. Recent examination of evolutionary histories of hosts and parasites and DNA evidence show that over 10,000 years ago, ancestors of modern humans in Africa became exposed to tapeworm when they scavenged for food or preyed on antelopes and bovids, and later passed the infection on to domestic animals such as pigs.
Cysticercosis was described by Johannes Udalric Rumler in 1555; however, the connection between tapeworms and cysticercosis had not been recognized at that time. Around 1850, Friedrich Küchenmeister
Friedrich Küchenmeister
Gottlieb Heinrich Friedrich Küchenmeister was a German physician.- Life :...
fed pork containing cysticerci of T. solium to humans awaiting execution in a prison, and after they had been executed, he recovered the developing and adult tapeworms in their intestines. By the middle of the 19th century, it was established that cysticercosis was caused by the ingestion of the eggs of T. solium.
Transmission
Humans are T. solium reservoirs. They are infected by eating undercooked pork that contains viable cysticerci. The cysticercus develops into an adult tape worm in the gut and produces large numbers of eggs which pass out in the feces. The presence of an adult tape worm in the gut is reasonably harmless. The condition known as cysticercosis in humans occurs due to the ingestion of tape worm eggs, either from external sources or from the person's own feces. The human has then become an accidental and "dead-end" intermediate host (that is, the infection can not progress any further). Pigs, which are the "normal" intermediate host for this parasite, get infected with cysticerci when they ingest human feces. The incubation period ranges from months to over ten years.Morphology
T. solium worms may reach a length of several meters. The scolex has four suckers, and a double crown of prominent hooks, which attach to the intestinal mucosa. T. solium eggs are spherical and 30 to 40 µm in diameter.The cysticercus larva completes development in about 2 months. It is semitransparent, opalescent white, and elongate oval in shape and may reach a length of 0.6 to 1.8 cm.
Life cycle
The life cycle involves humans as a definite host and pigs as an intermediate host. Pigs ingest contaminated food or water that contains eggs or proglottids from human’s feces. The ova develop into cysticercus in pig muscles. Human becomes infected when they ingest raw or undercooked “measly pork” that contains viable cysticercus. Upon reaching the small intestine, the scolex attaches to the intestinal wall and a proglottid chain grows. T. solium releases three to six proglottids/day, bearing 30,000 to 70,000 eggs (ovaOvum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
) per proglottid into the intestine. Nearly 250,000 ova are passed daily into the human feces and to the environment, and the cycle continues.
Infections with cysticercus occur after humans consume the ova from exogenous sources or through self-infection via the fecal-oral route. Humans, in this case, are intermediate hosts. Ova are digested in the stomach and release oncospheres which penetrate the intestinal wall and reach the bloodstream. These oncospheres develop into cysticerci in any organ but are common in brain, subcutaneous tissue, or eyes.
Cysticercosis in muscles
Cysticerci can develop in any voluntary muscle in humans. Invasion of muscle by cysticerci can cause myositisMyositis
Myositis is a general term for inflammation of the muscles. Many such conditions are considered likely to be caused by autoimmune conditions, rather than directly due to infection It is also a documented side effect of the lipid-lowering drugs statins and fibrates.Elevation of creatine kinase in...
, with fever, eosinophilia
Eosinophilia
Eosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds 0.45×109/L . A marked increase in non-blood tissue eosinophil count noticed upon histopathologic examination is diagnostic for tissue eosinophilia. Several causes are known, with the most common being...
, and muscular pseudohypertrophy, which initiate with muscle swelling and later progress to atrophy and fibrosis. In most cases, it is asymptomatic since the cysticerci die and become calcified.
Neurocysticercosis
The term neurocysticercosis is generally accepted to refer to cysts in the parenchymaParenchyma
Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, f. Greek παρέγχυμα - parenkhuma, "visceral flesh", f. παρεγχεῖν - parenkhein, "to pour in" f. para-, "beside" + en-, "in" + khein, "to pour"...
of the brain. It presents with seizures and, less commonly, headaches.
Intraventricular neurocysticercosis
Cysts located within the ventricles of the brain can block the outflow of cerebrospinal fluidCerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
and present with symptoms of increased intracranial pressure
Intracranial pressure
Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid . The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF...
.
Racemose neurocysticercosis
Racemose neurocysticercosis refers to cysts in the subarachnoid spaceSubarachnoid space
In the central nervous system, the subarachnoid cavity is the interval between the arachnoid membrane and pia mater....
. These can occasionally grown into large lobulated masses causing pressure on surrounding structures.
Spinal neurocysticercosis
Neurocysticercosis involving the spinal cord, most commonly presenting as back pain and radiculopathyRadiculopathy
Radiculopathy is not a specific condition, but rather a description of a problem in which one or more nerves are affected and do not work properly . The emphasis is on the nerve root...
.
Ophthalmic cysticercosis
In some cases, cysticerci may be found in the globe, extraocular muscles, and subconjunctiva. Depending on the location, they may cause visual difficulties that fluctuate with eye position, retinal edema, hemorrhage, a decreased vision or even a visual loss.Subcutaneous cysticercosis
Subcutaneous cysts are in the form of firm, mobile nodules, occurring mainly on the trunk and extremities. Subcutaneous nodules are sometimes painful.Diagnosis
The traditional method of demonstrating tapeworm eggs in stool samples diagnoses only taeniasis, carriage of the tapeworm stage of the life cycle. Only a small minority of patients with cysticercosis will harbor a tapeworm, rendering stool studies ineffective for diagnosis.In CDC’s immunoblot assay, cysticercosis-specific antibodies can react with structural glycoprotein antigens from the larval cysts of T. solium. However this is mainly a research tool not widely available in clinical practice and nearly unobtainable in resource limited settings.
The diagnosis of neurocysticercosis is mainly clinical, based on a compatible presentation of symptoms and findings of imaging studies. Neuroimaging with CT or MRI is the most useful method of diagnosis. CT scan shows both calcified and uncalcified cysts, as well as distinguishing active and inactive cysts. MRI is more sensitive in detection of intraventricular cysts.
Neurocysticercosis
Neurocysticercosis most often presents as headaches and acute onset seizures, thus the immediate mainstay of therapy is anticonvulsantAnticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
medications. Once the seizures have been brought under control, antihelminthic treatments may be undertaken. The decision to treat with antiparasitic therapy is complex and based on the stage and number of cysts present, their location, and the patient's specific clinical presentation. Antiparasitic treatment should be given in combination with corticosteroids and anticonvulsants to reduce inflammation surrounding the cysts and lower the risk of seizures. Albendazole
Albendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
is generally preferable over praziquantel
Praziquantel
Praziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....
due to its lower cost and fewer drug interactions.
Asymptomatic cysts, such as those discovered incidentally on neuroimaging done for another reason, may never lead to symptomatic disease and in many cases do not require therapy.
Calcified cysts have already died and involuted. Further antiparasitic therapy will be of no benefit.
Surgical intervention is much more likely to be needed in cases of intraventricular, racemose, or spinal neurocysticercosis. Treatments includes direct excision of ventricular cysts, shunting procedures, and removal of cysts via endoscopy.
Ophthalmic cysticercosis
In ophthalmic disease surgical removal is necessary for cysts within the eye itself, while antihelminth drug with steroids alone might be sufficient to treat cysts outside globe. Treatment recommendations for subcutaneous cysticercosis includes surgery, praziquantel and albendazole.Subcutaneous cysticercosis
In general, subcutaneous disease does not need specific therapy. Painful or bothersome cysts can be surgically excised.Public health and prevention strategies
Cysticercosis is considered as “tools-ready disease” according to WHO. International Task Force for Disease Eradication in 1992 reported that cysticercosis is potentially eradicable. It is feasible because there are no animal reservoirs besides humans and pigs. The only source of T. solium infection for pigs is from humans, a definite host. Theoretically, breaking the life cycle seems easy by doing intervention strategies from various stages in the life cycle.For example,
- Massive chemotherapy of infected individuals, improving sanitation, and educating people are all major ways to discontinue the cycle at Step 1, in which eggs from human feces are transmitted to other humans and/or pigs.
- Cooking of pork or freezing it and inspecting meat are effective means to cease the life cycle at Step 3.
- The management of pigs by treating them or vaccinating them is another possibility to intervene Step 4 of the life cycle.
- The separation of pigs from human faeces by confining them in enclosed piggeries. In Western European countries post World War 2 the pig industry developed rapidly and most pigs were housed. This was the main reason for pig cysticercosis largely being eliminated from the region. This of course is not a quick answer to the problem in developing countries.
Intervention by concurrent treatment of humans and pigs
The intervention strategies to eradicate cysticercosis includes surveillance of pigs in foci of transmission and massive chemotherapy treatment of humans. In reality, control of T. solium by a single intervention, for instance, by treating only human population will not work because the existing infected pigs can still carry on the cycle. The proposed strategy for eradication is to do multilateral intervention by treating both human and porcine populations. It is feasible because treatment pigs with oxfendazole have been shown to be effective and once treated, they are protected from further infections for at least 3 months.Limitations
Even with the concurrent treatment of humans and pigs, complete elimination is hard to achieve. In one study conducted in 12 villages in Peru, both humans and porcine were treated with praziquantel and oxfendazole, with the coverage of more than 75% in humans and 90% in pigs The result shows a decreased in prevalence and incidence in the intervention area; however the effect did not completely eliminate T. solium. The possible reason includes the incomplete coverage and re-infection. Even though T. solium could be eliminated through mass treatment of human and porcine population, it is not sustainable. Moreover, both tapeworm carriers of humans and pigs tend to spread the disease from endemic to non-endemic areas resulting in periodic outbreaks of cysticercosis or outbreaks in new areas.Vaccine against porcine cysticercosis
Given the fact that pigs are part of a life cycle, vaccination of pigs is another feasible intervention to eliminate cysticercosis. Research studies have been focusing on vaccine against cestode parasites, since many immune cell types are found to be capable of destroying cysticercus. Many vaccine candidates are extracted from antigens of different cestodes such as T. solium, T. crassiceps, T. saginata, T. ovis and target oncospheres and/or cysticerci. In 1983, Molinari et al. reported the first vaccine candidate against porcine cysticercosis using antigen from cysticercus cellulosae drawn out from naturally infected. Recently, vaccines extracted from genetically engineered 45W-4B antigens have been successfully tested to pigs in an experimental condition. This type of vaccine can protect against cysticercosis in both Chinese and Mexican type of T. solium. However, it has not been tested in endemic field conditions, which is important because the realistic condition in the field differ greatly from experimental condition, and this can result in a great difference in the chances of infection and immune reaction.The S3PVAC vaccine
The vaccine constituted by 3 peptide synthetically produced (S3Pvac) has proven its efficacy in natural conditions of transmission. The S3PVAC vaccine so far, can be considered as the best vaccine candidate to be used in endemic areas such as Mexico (20). S3Pvac consists of three protective peptides: KETc12, KETc1 and GK1, whose sequences belong to native antigens that are present in the different developmental stages of T. solium and other cestode parasites.Non-infected pigs from rural villages in Mexico were vaccinated with S3Pvac and the vaccine reduced 98% the number of cysticerci and 50% the number of prevalence. The diagnostic method involves necropsy and tongue inspection of pigs. The natural challenge conditions used in the study proved the efficacy of the S3Pvac vaccine in transmission control of T. solium in Mexico. The S3Pvac vaccine is owned by the National Autonomous University of Mexico and the method of high scale production of the vaccine has already been developed. The validation of the vaccine in agreement with the Secretary of Animal Health in Mexico is currently in the process of completion. It is also hoped that the vaccine will be well-accepted by pig owners because they also lose their income if pigs are infected cysticercosis. Vaccination of pigs against cysticercosis, if succeeded, can potentially have a great impact on transmission control since there is no chance of re-infection once pigs receive vaccination.
Limitations of vaccines
Even though vaccines have been successfully generated, the feasibility of its production and usage in rural free ranging pigs still remains a challenge. If a vaccine is to be injected, the burden of work and the cost of vaccine administration to pigs will remain high and unrealistic. The incentives of using vaccines by pig owners will decrease if the vaccine administration to pigs takes time by injecting every single pig in their livestock. An oral vaccine is proposed to be more effective in this case as it can be easily delivered to the pigs with the food, though no one has ever achieved it yet.Other types of interventions and limitations
Cysticercosis can also be prevented by routine inspection of meat and condemnation of measly meat by the local government. However, in areas where food is scarce, cyst-infected meat might be considered as wasted since pork can provide high quality protein. At times, infected pigs are consumed within the locality or sold at low prices to traffickers who take the uninspected pigs at urban areas for sale.Due to these limitations, cysticercosis has not been eliminated in any endemic areas.
Epidemiology
The tapeworm that causes cysticercosis is endemicEndemic (epidemiology)
In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. For example, chickenpox is endemic in the UK, but malaria is not...
to many parts of the world including China, Southeast Asia, India, sub-Saharan Africa, and Latin America. Some studies suggest that the prevalence of cysticercosis in Mexico is between 3.1 and 3.9 percent. Other studies have found the seroprevalence
Seroprevalence
Seroprevalence is the number of persons in a population who test positive for a specific disease based on serology specimens; often presented as a percent of the total specimens tested or as a proportion per 100,000 persons tested...
in areas of Guatemala, Bolivia, and Peru as high as 20 percent in humans, and 37 percent in pigs. In Ethiopia, Kenya and the Democratic Republic of Congo around 10% of the population is infected, in Madagascar 16%. The frequency has decreased in developed countries owing to stricter meat inspection, better hygiene and better sanitary facilities. The distribution of cysticercosis coincides with the distribution of T. solium. Cysticercosis is the most common cause of symptomatic epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
worldwide.
In Latin America, an estimated 75 million persons live in endemic areas and 400,000 people have symptomatic disease. Cysticercosis is also found to be associated with Hispanic ethnicity, immigrant status, and exposure to areas of endemicity. In the US, the disease is found in immigrants from Mexico, Central and South America. Current livestock for pigs in the U.S do not play a role in the transmission of Taenia solium, and thus cysticercosis in the U.S is an imported disease.
In the USA during 1990–2002, 221 cysticercosis deaths were identified. Mortality rates were highest for Latinos and men. The mean age at death was 40.5 years (range 2–88). Most patients, 84.6%, were foreign born, and 62% had emigrated from Mexico. The 33 US-born persons who died of cysticercosis represented 15% of all cysticercosis-related deaths. The cysticercosis mortality rate was highest in California, which accounted for ˜60% of all deaths.
In popular culture
- The first patient on the television show HouseHouse (TV series)House is an American television medical drama that debuted on the Fox network on November 16, 2004. The show's central character is Dr. Gregory House , an unconventional and misanthropic medical genius who heads a team of diagnosticians at the fictional Princeton-Plainsboro Teaching Hospital in...
(in the pilot episodePilot (House)"Pilot", also known as "Everybody Lies", is the first episode of the U.S. television series House. The episode premiered on the Fox network on November 16, 2004. It introduces the character of Dr. Gregory House —a maverick antisocial doctor—and his team of diagnosticians at the fictional...
) suffered from cysticercosis. - In the crossover of the series Grey's AnatomyGrey's AnatomyGrey's Anatomy is an American medical drama television series created by Shonda Rhimes. The series premiered on March 27, 2005 on ABC; since then, seven seasons have aired. The series follows the lives of interns, residents and their mentors in the fictional Seattle Grace Mercy West Hospital in...
(season 5, episode 15Before and After (Grey's Anatomy)"Before and After" is the fifteenth episode of the fifth season of the ABC series, Grey's Anatomy. It aired on February 12, 2009.-Episode Summary:...
) and Private Practice (season 2), Archer Montgomery, brother of Addison Forbes MontgomeryAddison MontgomeryAddison Adrienne Forbes Montgomery , was a fictional character on the ABC television series Grey's Anatomy, and is currently starring on its spin-off show Private Practice. Addison is a world-class neonatal surgeon with board certifications in both Obstetrics and Gynaecology and Maternal and Fetal...
, suffered from neurocysticercosis. He was cured via the surgical removal of the cysts by his former brother-in-law Derek ShepherdDerek ShepherdDerek Christopher Shepherd, also referred to as McDreamy, is a fictional surgeon on the ABC television series Grey's Anatomy. The character is portrayed by actor Patrick Dempsey, who was nominated in 2006 and 2007 Golden Globe for the Best Performance by an Actor in a Television Series Drama for...
.
External links
- Neurocysticercosis MR and CT scans