170 Am. J. Trop. Med. Hyg., 66(2), 2002, pp. 170–174 Copyright  2002 by The American Society of Tropical Medicine and Hygiene SEROLOGICAL EVIDENCE FOR RECENT EXPOSURE TO TAENIA SOLIUM IN VENEZUELAN AMERINDIANS E. FERRER, M. M. CORTEZ, H. PEREZ, M. DE LA ROSA, B. ALARCON DE NOYA, I. DA ´ VILA, L. J. S. HARRISON, M. FOSTER-CUEVAS, R. M. E. PARKHOUSE, AND A. CABRERA Centro de Investigaciones Biomedicas BIOMED Universidad de Carabobo, Maracay, Venezuela; Instituto de Medicina Tropical, Universidad Central de Venezuela (UCV) Caracas, Venezuela; Departamento de Parasitologı ´a Universidad de Carabobo, Maracay, Venezuela; Centro de Microbiologia y Biologı ´a Celular IVIC Caracas Venezuela; University of Edinburgh, Department of Tropical Animal Health, Sir Alexander Robertson Centre for Tropical Veterinary Medicine, Easter Bush, Roslin, Midlothian, Scotland, United Kingdom; Institute for Animal Health, Pirbright laboroatory, Ash Road, Woking, Surrey, England, United Kingdom; Gulbenkian Institute for Science, Oeiras, Portugal Abstract. This study examined the seroprevalence and serum antibody isotype proﬁle for Taenia solium cysticer- cosis in an Amerindian community in the Amazonas state of Venezuela. An antigen-trapping enzyme-linked immu- nosorbent assay (Ag-ELISA) was used to detect viable cysticercosis. Indirect ELISA (Ab-ELISA) and enzyme-linked immunoelectrotransfer blot (EITB) was performed by using antigens prepared from T. solium metacestodes to detect anti-parasite antibodies. The Ag-ELISA and Ab-ELISAs revealed 64.7% and 79.0% seropositivity, respectively, in the Amerindian population. Immunoglobulin (Ig) M was the predominant antibody class, suggesting recent infection. In comparison sera from, clinically deﬁned, hospital neurocysticercosis cases revealed only 27% seropositivity by Ag-ELISA, compared with 86–92% seropositivity by Ab-ELISA, and IgG 4 was the predominant antibody subclass detected. The EITB antigen recognition patterns of the hospitalized patients were very similar to that of the Amer- indians, conﬁrming exposure to the parasite. These results, combined with the predominance of IgM antibody re- sponses and the marked detection of secreted products of viable parasites, strongly suggest that recent exposure to T. solium had occurred in the Amerindian population. INTRODUCTION Taenia solium cysticercosis and neurocysticercosis in hu- mans is an important public health problem in Latin Amer- ica. 1–3 The disease is found in areas with poor sanitary con- ditions where pigs are raised freely. Transmission of cysti- cercosis is by ingestion of T. solium eggs from the environ- ment and through contaminated hands, water, or food, and autoinfection also occurs. 4 The occurrence of the infection is linked to social, economic, and environmental character- istics and is found predominantly in rural areas of endemic countries. Many epidemiological studies have been carried out in such rural populations of Latin American countries. 5–9 In Venezuela, however, there is a paucity of information on the prevalence and socioeconomic impact of cysticercosis. Most available information is derived from urban clinical centers. 10 Health Ministry data for 1996 revealed only 4 fatal cases of cysticercosis, 11 but these data are incomplete and do not reﬂect disease prevalence or associated morbidity in the communities at risk. 2,8,12 The prevalence of cysticercosis and neurocysticercosis in Amerindian communities is largely unknown. The aim of this study was to conduct a systematic sero- logical study in such a community and to compare the results with a group of clinically veriﬁed cases of neurocysticer- cosis. Thus, in these 2 different population groups, the prev- alence of viable parasite infection was evaluated through an antigen-detection enzyme-linked immunosorbent assay (Ag- ELISA). The value of this assay in the diagnosis treatment and follow-up of patients with neurocysticercosis has been evaluated. 13,14 Antibody and antigen recognition proﬁles and antibody isotype responses were examined by enzyme- linked immunoelectrotransfer blot (EITB) and indirect ELISA (Ab-ELISA) assays. MATERIALS AND METHODS Serum samples. Informed consent was obtained from all the adults participating in the study and from the parents or legal guardians of minors. The project was approved by the institutional review board (Dirreccion de Investigacion de Universidad de Carabobo Nucleo Aragua). Amerindian test sera. The blood samples were taken dur- ing a vaccination campaign against yellow fever, measles, poliomyelitis, and diphtheria-tetanus-pertussis carried out by the Venezuelan Ministry of Health. They were obtained from Amerindians living in the Venezuelan state of Amazonas. All the study subjects lived in ﬁxed locations near the riv- erbank, far from non-Amerindian communities and urban ar- eas. This population makes few or no visits to urban centers. There is a general lack of sanitary and hygiene facilities in these communities. The people live communally, with no access to piped water or latrines. Although pork is not con- sidered an important part of the Amerindian diet, it is eaten occasionally; in addition, contact with other ethnic groups or environmental contamination with T. solium eggs cannot be ruled out. As far as can be determined, there are no known wild-game reservoirs of T. solium, and certainly there are none locally. For reasons of medical ethics, the serum sampling was restricted to the participants in the vaccination program. It was not possible to obtain samples of feces because the be- liefs of the Amerindians would not permit such sampling. The 68 samples were randomly chosen for analysis in the study. The main criterion was availability of serum sufﬁcient to carry out the analysis. All the Amerindians were asymp- tomatic at the time of serum sampling. The Amerindians were inhabitants of the following zones: San Juan de Manapiare, Morrocoy, Macuruco, Laja Pela ´, Laguna de Tigre, Magua, and Maroeta y la Venturosa. They belonged to various Amerindian ethnic groups, as follows: