The Incidence of Human Cysticercosis in a Rural Community of Eastern Zambia

Kabemba E. Mwape,Isaac K. Phiri,Pierre Dorny,Nicolas Praet,Niko Speybroeck,John B. Muma,Sarah Gabriël,Ana Flisser

doi:10.1371/journal.pntd.0002142

Abstract

A community-based longitudinal study was performed in the Eastern Province of Zambia, in which repeated serological samplings were done to determine the incidence of human cysticercosis. Three sampling rounds were carried out at six months intervals. A total of 867 participants presented for all three samplings. All samples were tested for the presence of cysticercus antigens using a monoclonal antibody-based enzyme-linked immunosorbent assay (sero-Ag-ELISA), while a randomly selected sub-sample of 161 samples from each sampling round was tested for specific antibodies using a commercial enzyme-linked immunoelectrotransfer blot (EITB) assay. Stool samples (n = 226) were also collected during the final round of sampling for taeniosis diagnosis by coprology and coproantigen ELISA. Cysticercosis seroprevalence varied from 12.2% to 14.5% (sero-Ag) and from 33.5% to 38.5% (sero-Ab) during the study period. A taeniosis prevalence of 11.9% was determined. Incidence rates of 6300 (sero-Ag, per 100000 persons-year) and 23600 (sero-Ab, per 100000 persons-year) were determined. Seroreversion rates of 44% for sero-Ag and 38.7% for sero-Ab were recorded over the whole period. In conclusion, this study has shown the dynamic nature of T. solium infections; many of the people at risk become (re)infected due to the high environmental contamination, with a high number turning seronegative within a year after infection. An important number of infections probably never fully establish, leading to transient antibody responses and short-term antigen presence.

Highlights

Human cysticercosis, an infection caused by the metacestode larval stage of the pork tapeworm Taenia solium, is a serious but neglected zoonotic disease and a major public health problem in many developing countries of Latin America, Asia and Africa [1,2]
In terms of Disability Adjusted Life Years (DALYs), the global burden of epilepsy is estimated at 7.8 million DALYs with 6.5 million of these occurring in T. solium endemic regions of the world [5]
Sampling A total of 3167 serum samples and 226 stool samples were examined for cysticercosis and taeniosis, respectively

Summary

Introduction

Human (neuro) cysticercosis, an infection caused by the metacestode larval stage of the pork tapeworm Taenia solium, is a serious but neglected zoonotic disease and a major public health problem in many developing countries of Latin America, Asia and Africa [1,2]. When the larval stages invade the nervous system they cause neurocysticercosis (NCC), which is the most important parasitic disease affecting the nervous system and accounts for about 30% of all acquired epilepsy cases in endemic areas [4]. The few community based human prevalence studies carried out in Africa have indicated sero-prevalences of human cysticercosis ranging from 7–22% [e.g. 6,7,8]. In a recent study in Zambia, a sero-prevalence of 5.8% has been recorded in a rural community in the eastern part of Zambia [9]

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Conclusion