Echinococcosis in humans is a zoonotic infection caused by larval stages (metacestodes) of cestode species of the genus Echinococcus. Cystic echinococcosis (CE) is caused by Echinococcus granulosus, alveolar echinococcosis (AE) is caused by E. multilocularis, and polycystic forms are caused by either E. vogeli or E. oligarthrus. In untreated cases, AE has a high mortality rate. Although control is essentially feasible, CE remains a considerable health problem in many regions of the northern and southern hemispheres. AE is restricted to the northern hemisphere regions of North America and Eurasia. Recent studies have shown that E. multilocularis, the causative agent of AE, is more widely distributed than previously thought. There are also some hints of an increasing significance of polycystic forms of the disease, which are restricted to Central and South America. Various aspects of human echinococcosis are discussed in this review, including data on the infectivity of genetic variants of E. granulosus to humans, the increasing invasion of cities in Europe and Japan by red foxes, the main definitive hosts of E. multilocularis, and the first demonstration of urban cycles of the parasite. Examples of emergence or reemergence of CE are presented, and the question of potential spreading of E. multilocularis is critically assessed. Furthermore, information is presented on new and improved tools for diagnosing the infection in final hosts (dogs, foxes, and cats) by coproantigen or DNA detection and the application of molecular techniques to epidemiological studies. In the clinical field, the available methods for diagnosing human CE and AE are described and the treatment options are summarized. The development of new chemotherapeutic options for all forms of human echinococcosis remains an urgent requirement. A new option for the control of E. granulosus in the intermediate host population (mainly sheep and cattle) is vaccination. Attempts are made to reduce the prevalence of E. multilocualaris in fox populations by regular baiting with an anthelmintic (praziquantel). Recent data have shown that this control option may be used in restricted areas, for example in cities, with the aim of reducing the infection risk for humans.

Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern

/pdf/who-oie-manual-on-echinococcosis-in-humans-and-animals-a-3oxkh54un8.pdf

WHO/OIE manual on echinococcosis in humans and animals: a public health problem of global concern.

An enzyme-linked immunoelectrotransfer blot (EITB) assay was developed for immunodiagnosing human cysticercosis. The assay uses lentil-lectin, affinity-purified glycoprotein antigens. A battery of 532 serum and 46 cerebrospinal fluid (CSF) samples (148 cases of parasitologically confirmed cysticercosis, 54 healthy controls, and 18 types of heterologous infections [376 cases]) were used to ascertain the assay's efficacy. All but three of the samples from cases of confirmed cysticercosis were positive; none of the samples from healthy controls or heterologous infections reacted to any of the diagnostic bands. Thus, the assay is 98% sensitive and 100% specific. We identified seven major glycoprotein bands that are commonly recognized by virtually all serum and/or CSF samples from patients with confirmed cysticercosis. There was no significant difference in test performance when CSF was compared with serum. The EITB assay is highly reproducible and simple to perform, and the reagents (including the antigens blotted onto strips) are very stable.

An Enzyme-Linked Immunoelectrotransfer Blot Assay and Glycoprotein Antigens for Diagnosing Human Cysticercosis (Taenia solium)

Neurocysticercosis is the most common helminthic infection of the CNS but its diagnosis remains difficult. Clinical manifestations are nonspecific, most neuroimaging findings are not pathognomonic, and some serologic tests have low sensitivity and specificity. The authors provide diagnostic criteria for neurocysticercosis based on objective clinical, imaging, immunologic, and epidemiologic data. These include four categories of criteria stratified on the basis of their diagnostic strength, including the following: 1) absolute--histologic demonstration of the parasite from biopsy of a brain or spinal cord lesion, cystic lesions showing the scolex on CT or MRI, and direct visualization of subretinal parasites by funduscopic examination; 2) major--lesions highly suggestive of neurocysticercosis on neuroimaging studies, positive serum enzyme-linked immunoelectrotransfer blot for the detection of anticysticercal antibodies, resolution of intracranial cystic lesions after therapy with albendazole or praziquantel, and spontaneous resolution of small single enhancing lesions; 3) minor--lesions compatible with neurocysticercosis on neuroimaging studies, clinical manifestations suggestive of neurocysticercosis, positive CSF enzyme-linked immunosorbent assay for detection of anticysticercal antibodies or cysticercal antigens, and cysticercosis outside the CNS; and 4) epidemiologic--evidence of a household contact with Taenia solium infection, individuals coming from or living in an area where cysticercosis is endemic, and history of frequent travel to disease-endemic areas. Interpretation of these criteria permits two degrees of diagnostic certainty: 1) definitive diagnosis, in patients who have one absolute criterion or in those who have two major plus one minor and one epidemiologic criterion; and 2) probable diagnosis, in patients who have one major plus two minor criteria, in those who have one major plus one minor and one epidemiologic criterion, and in those who have three minor plus one epidemiologic criterion.

Proposed diagnostic criteria for neurocysticercosis

http://www.bio.umass.edu/micro/klingbeil/590s/Reading/Cysticer2003.pdf

Taenia solium cysticercosis

Background and Methods. From June 1990 through July 1991, intracerebral infection with the larval stage of the pork tapeworm Taenia solium was diagnosed in four unrelated persons in an Orthodox Jewish community in New York City. None of the patients had eaten pork, and only one had traveled to a country in which T. solium infection was endemic. We investigated this outbreak, screened serum samples from family members and household contacts for antibodies to cysticercosis, and examined stool specimens from household employees for eggs of taenia species. Results. The four patients had recurrent seizures and brain lesions that were radiologically consistent with the presence of cysticerci. The diagnosis was confirmed in two patients by a brain biopsy, and in two by immunoblot assays for cysticercus antibodies. Of 17 immediate family members screened serologically, 7 from two families had cysticercus antibodies. Magnetic resonance imaging of the brain showed cystic lesions in two of the seropositive ...

https://www.nejm.org/doi/pdf/10.1056/NEJM199209033271004

Neurocysticercosis in an orthodox jewish community in New York City

Epidemiology and control of hydatid disease

Geographic distribution and prevalence.

Taeniasis, or cysticercosis, caused by Taenia solium (often referred to as the pork tapeworm), is a classical zoonosis which has been recognized since antiquity. Cysticercosis is acquired by ingesting Taenia eggs shed in the feces of a human tapeworm carrier and may occur in humans who neither eat pork nor share environments with pigs. Although cysticerci may localize throughout the body, most clinical manifestations result from their presence in the central nervous system (neurocysticercosis (NCC)), where they can cause seizures, hydrocephalus, and other neurologic dysfunctions. 175 patients with active neurocysticercosis were randomly assigned to three treatment groups: (i) oral prednisolone alone, (ii) praziquantel (50 mg/kg for 15 days) with prednisolone, or (iii) albendazole (15 mg/kg) for 8 days with prednisolone. The results of this study suggest that still reliable criteria to determine which patients require treatment with either praziquantel or albendazole is lacking. Approximately half of the patients in this study had anticysticercal antibodies that recognized all seven of the diagnostic proteins. Although local persons are usually unaware of the threat to public health that this infection in pigs represents and do not relate the lesions in their animals to disease in humans, pig owners routinely check their live pigs for cysticercosis by direct examination of the tongue. Special studies reveal that morbidity caused by NCC is measurable and severe in areas where NCC is endemic.

Immigrants, Imaging, and Immunoblots: the Emergence of Neurocysticercosis as a Significant Public Health Problem

Four hundred ninety-seven patients were identified as having been treated for cysticercosis at four hospitals in Los Angeles during the 11-year period 1973 through 1983. Eleven deaths were recorded. Over 90% of these patients were Hispanics in productive age groups; the majority were Mexican by nationality. Hospitalizations were generally short, and readmissions for recurrence of symptoms or complications of therapy occurred in only 14% of patients. Cysticercosis was diagnosed in 12 US citizens who had no history of travel to countries considered traditionally endemic for Taenia solium taeniasis/cysticercosis. A dramatic rise in numbers of cases was observed after 1977, appearing to plateau at approximately 80 cases per year in 1981. The increase in cases beginning in 1977 coincided with the introduction of the computed tomographic scan. ( JAMA 1985;254:3444-3448)

Peter M. Schantz

Papers

Neurocysticercosis in an orthodox jewish community in New York City

Epidemiology and control of hydatid disease

Geographic distribution and prevalence.

Immigrants, Imaging, and Immunoblots: the Emergence of Neurocysticercosis as a Significant Public Health Problem

Cysticercosis in Los Angeles County.