This seminar is based on papers published in the past 15 years in English, Spanish, or Portuguese selected from MEDLINE by use of the PubMed system with keywords “cysticercosis”, “neurocysticercosis”, “Taenia solium”, “epilepsy”, and “seizures”. Older articles were selected from the private collections of the authors and the archives of the Cysticercosis Working Group in Peru.
SeminarTaenia solium cysticercosis
Section snippets
Taeniasis
Taeniasis occurs only in the human host, after ingestion of undercooked pork infected with cysticerci. Although cysticercosis has been known for ages, its relation to the adult tapeworm was not clear until it was shown by Kuchenmaister in 1855; he fed condemned prisoners with cysticercosis-infected pork and recovered young tapeworms at autopsy.5 The larvae evaginate in the small intestine; the head (scolex) attaches to the mucosa and begins forming segments (proglottids). T solium has a scolex
Human cysticercosis
Cysticercosis is infection with the larval stage of the parasite. Human beings acquire cysticercosis through faecal-oral contamination with T solium eggs from tapeworm carriers.1, 4, 25 Thus, vegetarians and other people who do not eat pork can acquire cysticercosis.26 Water, wind, flies, and other indirect means of infection play little part in transmission.27 Internal autoinfection by regurgitation of proglottids into the stomach in taeniasis has been proposed but not proven.1, 27
Neurocysticercosis
The parasite commonly infects the central nervous system, causing neurocysticercosis, a pleiomorphic clinical disorder. After entering the central nervous system, cysticerci are viable and elicit few inflammatory changes in the surrounding tissues. Cysticerci may remain for a long time in this stage, protected by the blood-brain barrier6, 38, 39 and active immune-evasion mechanisms by the cysticerci.6 After a variable and unknown time (estimated to be several years on the basis of classic
Serology
A finding of eosinophils in the cerebrospinal fluid suggests the diagnosis of neurocysticercosis. Other routine laboratory tests scarcely contribute, and thus the diagnosis rests on serology and neuroimaging. Although both are highly sensitive and specific, perfect correlation should not be expected since their approaches differ.
Until recently, serological diagnosis of cysticercosis was less than satisfactory. The most commonly used ELISA cross-reacts with Hymenolepis nana and Echinococcus
Prognosis and natural evolution
Panel 2 shows research needs in T solium infection. There are few data on the natural evolution of neurocysticercosis, and those available are from historical controls in open treatment trials. As far as is known, the evolution of intraparenchymal neurocysticercosis follows a favourable course with degeneration of parasites and formation of residual calcified scars.79 When the parasites locate in the subarachnoid space or the ventricles, the morbidity and mortality are much higher because of
Treatment
Cysticercosis outside the nervous system is a benign disorder and does not merit specific treatment. Neurocysticercosis, however, is associated with substantial morbidity and mortality. Until 1978, the only treatments available were surgery for cyst excision or ventricular shunts or steroids to decrease inflammation. Praziquantel, first used in porcine cysticercosis, was the first effective specific antiparasitic drug.82, 83, 84 Later, albendazole added a cheaper and more effective alternative.
Porcine cysticercosis
In places with inadequate disposal of human faeces, pigs ingest stools containing T solium eggs. Cysticerci lodge anywhere in the body of the pig, most commonly in the muscle and subcutaneous fat. Pigs with cysts in the brain are a subset of those with more cysts in the carcass (Cysticercosis Working Group in Peru 2002, unpublished data). Although some pigs have massive infections, porcine cysticercosis is rarely associated with symptoms of any kind. Most pigs are killed before the age of 9
Epidemiology
Cysticercosis affects thousands of individuals in less developed countries1, 3 and in more developed countries with a high rate of immigration from endemic areas.2, 4 In endemic countries taeniasis/cysticercosis is extremely common, and neurologically symptomatic individuals, although many, represent only the tip of the iceberg. In most endemic villages more than 10% of the general population are seropositive, and the proportion can reach 25%. In population-based studies, 10–18% of asymptomatic
Control of taeniasis and cysticercosis
T solium is transmitted mainly in rural areas where pigs have access to untreated human sewage or faeces and infected pork is widely available. An estimated 400 000 people have symptomatic neurocysticercosis in Latin America alone.134 More developed countries eradicated cysticercosis by improving sanitation and controlling domestic pig-raising.135, 136 Since little socioeconomic development in endemic areas is expected in the near future, intervention measures for control and eradication are
Search strategy
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Failure of one-day praziquantel treatment in patients with multiple neurocysticercosis lesions
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Relationship between epilepsy and tropical diseases
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Immigrants, imaging and immunoblots: the emergence of neurocysticercosis as a significant public health problem
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Taenia solium: description of the intestinal implantation sites in experimental hamster infections
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Prevalence of taeniosis among patients with neurocysticercosis is related to severity of infection
Neurology
Heavy nonencephalitic cerebral cysticercosis in tapeworm carriers
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Guidelines for surveillance and control of Taeniasis/Cysticercosis
Cysticercosis and taeniasis
N Engl J Med
Epidemiology of intestinal taeniasis in four, rural, Guatemalan communities
Ann Trop Med Parasitol
Field trial of the coproantigen-based diagnosis of Taenia solium taeniasis by enzyme-linked immunosorbent assay
Am J Trop Med Hyg
Hyperendemic human and porcine Taenia solium infection in Peru
Am J Trop Med Hyg
Differentiating Taenia solium and Taenia saginata infections by simple hematoxylin-eosin staining and PCR-restriction enzyme analysis
J Clin Microbiol
Taenia saginata (Cestoda) in western Kenya: the reliability of faecal examinations in diagnosis
Parasitology
Albendazole therapy for neurocysticercosis: a prospective double-blind trial comparing 7 versus 14 days of treatment
Neurology
Immunodiagnosis of taeniasis by coproantigen detection
Parasitology
Differential diagnosis of Taenia saginata and Taenia solium infection by PCR
J Clin Microbiol
Development of a serologic assay to detect Taenia solium taeniasis
Am J Trop Med Hyg
Niclosamide therapy for tapeworm infections
Ann Intern Med
Increased prevalence of cysticercosis and taeniasis among professional fried pork vendors and the general population of a village in the Peruvian highlands
Am J Trop Med Hyg
Neurocysticercosis in an Orthodox Jewish community in New York City
N Engl J Med
Failure to incriminate domestic flies (Diptera: Muscidae) as mechanical vectors of Taenia eggs (Cyclophyllidea: Taeniidae) in rural Mexico
J Med Entomol
Recent advances in the diagnosis and treatment of cerebral cysticercosis
N Engl J Med
Studies on the post-embryonal development of Taenia solium: III on the development of Cysticercus cellulosae within the definitive intermediate host
J Med Assoc Formosa
Epilepsy in cysticercosis (Taenia solium); a study of seventy-one cases
QJM
Parasites in fine needle breast aspirates—assessment of host tissue response
Postgrad Med J
Anatomopathological aspects of human brain cysticercosis
Taenia solium ocular cysticercosis: findings in 30 cases
Ann Ophthalmol
Disseminated cysticercosis: new observations, including CT scan findings and experience with treatment by praziquantel
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Optic nerve cysticercosis: imaging findings
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Visual loss in cysticercosis: analysis of 23 patients
Neurology
The immunology of the host-parasite relationship in Taenia solium cysticercosis: implications for prevention and therapy
Cysticercosis as seen in the British army with special reference to the production of epilepsy
Trans R Soc Trop Med Hyg
Cysticercosis (Taenia solium): a further ten years' clinical study, covering 284 cases
QJM
Epilepsy due to neurocysticercosis: analysis of 203 patients
Neurology
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