Prevalence of Taenia solium cysticercosis in swine from a community-based study in 21 villages of the Eastern Cape Province, South Africa.

The pork tapeworm, Taenia solium, causative organism of porcine cysticercosis and human neurocysticercosis is known to occur in areas of South Africa including Eastern Cape Province but, despite increasing reports of its occurrence throughout the subregion, the prevalence is yet to be clearly established. The parasite presents a potentially serious agricultural problem and public health risk in endemic areas. The human populations considered to be at highest risk of infection with this zoonotic helminth are people living in rural areas most of whom earn their livelihood wholly or partially through livestock rearing. Here we report on initial results of a community-based study of pigs owned by resource-poor, emerging pig producers from 21 villages in the Eastern Cape Province. Lingual examination (tongue palpation) in live pigs, two enzyme-linked immunosorbent assays (ELISAs), which detect parasite antigen (B158/B60 Ag-ELISA and HP10 Ag-ELISA) and an enzyme immunotransfer blot (EITB) assay, which detects antiparasite antibody, were used to verify endemicity and estimate apparent prevalence. In the absence of a gold standard true prevalence was obtained, using a Bayesian approach, with a model that uses both available data and prior information. Results indicate that the parasite is indeed present in the study villages and that true prevalence was 64.6%. The apparent prevalences as measured by each of the four tests were: 11.9% for lingual examination, 54.8% for B158/B60 Ag-ELISA, 40.6% for HP10 Ag-ELISA and 33.3% for EITB. This base-line knowledge of the prevalence of T. solium in pigs provides information essential to the design and monitoring of sustainable and appropriate interventions for cysticercosis prevention and control.

[Biological features of a new Echinococcus species (Echinococcus shiquicus) in the east of Qinghai-Tibet Plateau].

In the eastern Qinghai-Tibet Plateau region, a variety of domestic and wild mammals are involved in the transmission cycles of Echinococcus species. E. granulosus and E. multilocularis are known being sympatrically distributed in the plateau region. Recently, an unknown Echinococcus species was isolated from infected plateau pika (Ochotona curzoniae) and Tibetan fox (Vulpes ferrilata). The species shows quite distinct characteristics on morphology, genetics, host specificity and geographical distribution from others. It was therefore identified as a new Echinococcus species, Echinococcus shiquicus. This paper discussed the biological genetics and epidemiological features of the species, and proposed hypotheses and considerations for further exploration.

Proposed diagnostic criteria for neurocysticercosis.

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.

Serologic diagnosis of zoonotic pulmonary dirofilariasis.

Four symptomatic and four asymptomatic patients with histologically confirmed zoonotic pulmonary dirofilariasis caused by Dirofilaria immitis (dog heartworm) were evaluated serologically. Five patients had diagnostic indirect hemagglutination titers to D. immitis and six had positive findings by enzyme-linked immunosorbent assay. Of the two patients that had nondiagnostic titers by both enzyme-linked immunosorbent assay and indirect hemagglutination, one had an encapsulated necrotic adult worm that appeared to have been dead for some time, and the serum specimen for the second patient had been obtained five months following surgical removal of the granuloma. These findings suggest good sensitivity for these serologic methods in active cases, but declining antibody titers and decreased sensitivity following worm death. In general, cross-reactivity of the enzyme-linked immunosorbent assay with serum from patients with other nonfilarial parasitic infections or neoplasms was not observed.

Epilepsy and neurocysticercosis in an Andean community.

BACKGROUND: Taenia solium neurocysticercosis (NCC) has been documented as one of the major causes of epilepsy in developing countries. However, methodological limitations have hindered the evaluation of the epidemiological relationship between cysticercosis and epilepsy at the community level. METHODS: We used the WHO protocol for epidemiological evaluation of neurological disorders to conduct a door-to-door survey among 2723 residents of San Pablo del Lago, an Ecuadorean rural community in which T. solium taeniasis/cysticercosis was known to be endemic. The WHO protocol was complemented by neuroimaging and immunological tests to confirm the diagnosis of this infection. RESULTS: In all 31 people suffering from active epilepsy were detected (prevalence 11.4 per 1000, 95% CI:7.7-15.4); 26 agreed to undergo a computer tomography (CT) examination, and 28 agreed to have blood drawn for serodiagnosis. Fourteen of the 26 (53.8%) had CT changes compatible with NCC and six of the 28 (21.4%) tested positive in the enzyme-linked immunoelectro-transfer blot (EITB) assay. In a seizure-free random sample of this population, 17 of 118 (144 per 1000) subjects examined by CT and 10 out of 96 (104 per 1000) examined by EITB had evidence of this infection. The differences between the epilepsy group and the random sample of the population were statistically significant (OR = 6.93, 95% CI: 2.7-17.5, P < 0.001) for CT diagnosis, but not for EITB results (OR = 2.75, 95% CI: 0.8-7.1, P > 0.12, NS). CONCLUSIONS: These findings confirm that T. solium NCC is a significant cause of epilepsy at the community level in Andean villages of Ecuador. It is important to initiate effective public health interventions to eliminate this infection, which may be responsible for at least half of the cases of reported epilepsy in Ecuador.

Echinococcal disease.

Diagnosis of infection by the larval stages of Echinococcus granulosus, E. multilocaris, and E. vogeli, has increased in most parts of the world because of improved diagnostic technology, active surveillance, and increasing rates of transmission. Specific immunodiagnostics and sophisticated imaging techniques have made diagnosis more sensitive and specific. Surgery, performed by an experienced team with adequate postoperative support, remains the mainstay of therapy; however, alternative treatments, including chemotherapy and percutaneous cyst drainage, are used increasingly to aid in the management of inoperable echinococcal disease and, in some cases, for primary therapy. This article incorporates data from widely disparate sources and attempts a summary of the state-of-the-art diagnosis and treatment of echinococcal disease.

Mammomonogamus infection in a human. Report of a case.

Infection of humans by Mammomonogamus is rare, with approximately 80 cases reported in the literature. When present in man, the worms cause violent coughing until their removal. The diagnosis of Mammomonogamus infection in the past has been based on morphologic characteristics of intact adults. We report a case diagnosed by features of the worms in histologic section.

Long term follow-up of human hydatid disease (Echinococcus granulosus) treated with a high-dose mebendazole regimen.

Fifteen patients with inoperable hydatid disease (Echinococcus granulosus) were treated with an initial 6-week high-dose mebendazole regimen with a follow-up ranging from 3-7 years. Ten of 15 patients showed both objective and clinical improvement, although two of these 10 relapsed 1-6 years after completing therapy. Simple, single cysts in the lung and liver showed the best response. Multiple, complex cysts and bone cysts showed little or no objective improvement. One patient developed reversible neutropenia. Overall results were no better than those obtained by others with smaller doses.

Demonstration of species-specific and cross-reactive components of Taenia solium metacestode antigens.

Analysis of human serum reactivities to antigenic components of soluble Taenia solium metacestode proteins showed the predominant presence of determinants shared by T. solium, Echinococcus multilocularis and E. granulosus. Two polypeptides were demonstrated by SDS-PAGE and Western blot or enzyme-linked immunoelectrotransfer blot (EITB) assay to bind serum and CSF antibodies only from T. solium cysticercosis patients. These species-specific antigenic polypeptides focused between pH 4.6 and 3.9 after resolution by isoelectric focusing followed by EITB. The high species-specificity demonstrated by the present techniques offers the opportunity to confirm serologically an infection by T. solium metacestode.

Em18, a new serodiagnostic marker for differentiation of active and inactive cases of alveolar hydatid disease.

We determined whether detection of antibody response against a newly detected epitope, designated Em18, among Echinococcus multilocularis antigens could be a reliable marker for differentiation of active cases of alveolar hydatid disease (AHD) from inactive cases. Fifteen Alaskan patients with either active or inactive lesions of AHD previously confirmed clinically, pathologically, and serologically by the Em2-enzyme-linked immunosorbent assay (ELISA) were used for a blind test by Western blotting. Ten and five cases were considered to be active and inactive cases, respectively. One of the 10 cases classified serologically as active was judged to be inactive based on clinical and pathologic criteria; the patient had a recognizable parasitic lesion, and following short-term treatment with albendazole, a biopsy of the liver showed a degenerated lesion that did not grow in rodents. The five cases judged to be inactive included two confirmed inactive cases with cicatrized lesions and three active cases that showed the weakest values in the Em2-ELISA. The most predominant IgG subclass responding to Em18 was IgG4. In general, there were good correlations between 1) the antibody response against Em18 and the presence of active lesions and 2) the antibody response against Em18 and the Em2-ELISA values.

Trichinosis acquired at sea--report of an outbreak.

In 1974, at least 13 persons acquired trichinosis aboard a luxury liner en route to Alaska. Epidemiologic investigation implicated ground beef served on the ship as the vehicle of transmission. The beef is thought to have been contaminated by pork which had previously been frozen, though presumably not under trichinacidal conditions. To our knowledge, this is the first report of trichinosis acquired at sea.

Serologic cross-reactions with sera from patients with echinococcosis and cysticercosis.

Serum specimens from persons with pathologically confirmed Echinococcus granulosus hydatidosis and Taenia solium cysticercosis were tested in indirect hemagglutination tests using both Echinococcus and Taenia antigens. There were cross-reactions with most sera, and it was not possible to distinguish specific reactions by comparing titers with the homologous or heterologous antigens. Using immunoelectrophoresis or double diffusion tests with E. granulosus antigens, the Echinococcus-specific arc 5 was demonstrated in 11 of 21 hydatidosis sera and in 1 of 20 cysticercosis sera.

Clinical, serologic, and epidemiologic characteristics of ocular toxocariasis.

The clinical, serologic, and epidemiologic characteristics of 17 cases of ocular toxocariasis (OT) were studied and compared with those of a control group of 15 cases of other ocular diseases whose differential diagnosis included retinoblastoma. The prevalence and mean titers of Toxocara antibody detected by enzyme-linked immunosorbent assay were greater (P less than 0.005) for patients with OT than for the control group, but not all clinically diagnosed OT cases had detectable antibody. The prevalence of pica was significantly greater in cases than in controls (P less than 0.05). Almost all case and control patients had a history of exposure to pet dogs and cats, but recent exposure to puppies (less than 3 months old) was significantly associated with Toxocara infection in this study group.

Comparative sensitivity and specificity of the Casoni intradermal and the immunoelectrophoresis tests for the diagnosis of hydatid disease.

The Casoni intradermal (ID) test, using two antigens, was compared with the immunoelectrophoresis (IEP) test for diagnosis in 47 surgically confirmed cases of hydatid disease and 73 non-hydatid persons. An antigen prepared from boiled hydatid cyst fluid (HF) was markedly more sensitive in the ID test than another prepared from whole HF but both produced false-positive reactions in three persons with other disease conditions. The IEP test yielded no false positives and its sensitivity was similar to the ID test using the more sensitive boiled HF antigen. Some patients were ID-positive and IEP-negative and vice-versa. Diagnostic sensitivity of both tests varied according to the localization and condition of the cyst. A detectable immune response was more frequent in patients with liver cysts than in those with lung cysts. Regardless of cyst localization, lowest diagnostic sensitivity was observed in patients whose cysts were intact and of the hyaline type, whereas recently broken cysts were associated with the most consistently detectable immune response. The limitations of the ID test are discussed and it is suggested that, until more specific antigens are available, there appears to be little value in utilizing this test where the more specific serological techniques are available.

Nonspecific reactions with the intradermal test for hydatidosis in persons with other helminth infections.

A partially purified Echinococcus antigen solution, prepared by boiling hydatid cyst fluid, was used in the intradermal test for hydatid disease in a Peruvian population. An unexpectedly high rate of positive reactions and poor agreement with serological tests suggested the presence of some agent(s) which produced cross-reactions with Echinococcus granulosus antigens in the intradermal test. Testing of hospital patients infected with a variety of helminths demonstrated nonspecific reactions in persons with Hymenolepis nana, Taenia spp., and Fasciola hepatica infections, mixed parasitisms, and several non-helminth pathological conditions. The findings contraindicated the use of the intradermal test for epidemiological surveys of hydatid disease. It is pointed out that intradermal test positivity rates cannot be used as synonymous with infection prevalence and regional differences do not necessarily reflect differences in the prevalence of E. granulosus infection. The greater specificity of some serological tests favor their use for epidemiological purposes.

Trichinellosis in the United States, 1991-1996: declining but not gone.

Since the U.S. Public Health Service began recording statistics on trichinellosis in 1947, the number of cases reported by state health departments has decreased steadily. In the late 1940s, health departments reported an average of 400 cases and 10-15 deaths each year. From 1991 to 1996, the period covered in this report, three deaths in 230 cases were reported to the Centers for Disease Control and Prevention (an average of 38 cases per year), including 14 multiple case outbreaks from 31 states and Washington, DC. Information on the suspected food item was available for 134 (58%) of the 230 reported cases. Pork was implicated in 80 (60%) cases, bear meat in 31 (23%), walrus meat in 13 (10%), and cougar meat in 10 (7%). Sausage was the most frequently implicated pork product (i.e., 57 of the 64 cases for which the form of the pork product was identified). The proportion of trichinellosis cases attributable to consumption of commercial pork continued to decrease; this decrease was probably due to a combination of factors, including the continued reduction in the prevalence of Trichinella spiralis in domestic swine, the increased use of home freezers, and the practice of thoroughly cooking pork. As a proportion of all cases reported, those associated with wild game meat products has increased; however, the absolute numbers of such cases have remained similar at approximately 9-12 per year. The continued multiple case outbreaks and the identification of nonpork sources of infection indicate the need for further education and control measures.

Echinococcosis in Arizona and New Mexico. Survey of hospital records, 1969-1974.

In 1974, seven cases of human echinococcosis were diagnosed in Arizona and New Mexico. A retrospective survey of Arizona and New Mexico hospitals obtained data on ten additional cases reported for the 5-year period 1969 through 1973. Sixteen cases were diagnosed as Echinococcus granulosus infections and one as E. multilocularis infection. The latter infection was in an Eskimo from Alaska, where E. multilocularis is endemic. All of the 16 E. granulosus cases were probably acquired autochthonously; 14 were diagnosed in American Indians of the Navajo (8 cases), Zuni (4 cases), and Santo Domingo (2 cases) tribes; the remaining 2 cases were diagnosed in non-Indian women. This is the first published account of echinococcosis autochthonous to Arizona and New Mexico. Evidence suggests that the infection may have been introduced only relatively recently to the areas populated by the American Indians and that parasite transmission to humans is increasing.

Risk factors for infection with Echinococcus multilocularis in Alaska.

We studied 19 Eskimo patients with alveolar hydatid disease from the north-western coast of Alaska for risk factors for infection with Echinococcus multilocularis. Each case-patient was matched by age and sex with 2 unrelated controls who had no clinical or serologic evidence of infection with E. multilocularis and who resided in three villages endemic for alveolar hydatid disease. Behaviors thought to increase exposure to E. multilocularis and the chronologic occurrence of these behaviors in the participant's life were assessed by a standardized questionnaire. Case-patients were more likely than controls to have owned dogs for their entire lives (odds ratio 6.00, P less than 0.05), tethered their dogs near the house (odds ratio 8.50, P less than 0.05), and lived in houses built directly on the tundra rather than on gravel or a permanent foundation (odds ratio 11.00, P less than 0.01). Case-patients were not more likely to have owned sled dogs, trapped or skinned foxes, or engaged in other outdoor activities away from home. These findings suggest that controlling the parasite in the domestic dog population, as well as controlling the dog population itself, are important aspects of preventing alveolar hydatid disease in the northwestern Native Alaskan population.

Human subcutaneous Taenia solium cysticercosis in an Andean population with neurocysticercosis.

Subcutaneous involvement by the larval stages of the pork tapeworm Taenia solium in patients suffering from neurocysticercosis (neurocysticercosis) is well-described. It has been a clinical but undocumented impression that subcutaneous nodules are less common in cases of neurocysticercosis in Latin American than in Africa or Asia. We report on the absence of subcutaneous nodules found in a screened population of 2,891 residents of an Andean village in Ecuador with a prevalence rate for neurocysticercosis of 144 per thousand. Thirty-four patients with multiple intracranial calcifications and or cystic or encephalitic parenchymal lesions of neurocysticercosis were examined and questioned about subcutaneous nodules. Only one patient described nodules and this computed tomography plain films are presented. Several hypotheses are presented as to why nodules may be less common in this Andean community with a high prevalence of neurocysticercosis.

Spontaneous death of Echinococcus multilocularis: cases diagnosed serologically (by Em2 ELISA) and clinical significance.

Nine cases of asymptomatic alveolar hydatid disease (AHD) of the liver were diagnosed in 1985 among Eskimos from the endemic region of western Alaska. The patients were identified by screening with the enzyme-linked immunosorbent assay, using purified Echinococcus multilocularis antigen (Em2 ELISA). Five patients, and one diagnosed earlier (1979), were found to have lesions in which the larval E. multilocularis had died spontaneously at an early stage of infection. Viability was assessed histologically; by the avidin-biotin immunohistochemical method; and in vivo through intraperitoneal inoculation of membranes of the larval cestode into red-backed voles, Clethrionomys rutilus. The results were in agreement with the clinical impression, based on findings by computerized tomography and ultrasound scanning, and on the macroscopic appearance of the lesions, that the cestode was dead. Spontaneous death of E. multilocularis in humans has not been previously reported. The findings show that the Em2 ELISA may be positive in patients having lesions of AHD in which the etiologic agent is no longer viable.