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.
Description:
Human neurocysticercosis is an infection of the central
nervous system caused by the larval stage of the pork
tapeworm (Taenia solium). The infection occurs mainly in
developing countries and is associated with poverty, poor
sanitation and free-range pig management. It is estimated
to be responsible for 30% of cases of acquired epilepsy in
endemic areas. The limited number of human studies on
this infection in Sub-Saharan Africa determined a high
occurrence of cysticercosis. This study aimed to learn more
about the transmission dynamics of this parasite in a rural
endemic area in Eastern Zambia. A longitudinal study was
carried out in which 867 participants were blood sampled
three times, with a 6-month interval. Samples were
analysed for the presence of cysticercal circulating
antigens and specific antibodies. Results indicate that
about 1 on 3 people get exposed to infection while only 1
on 10 people actually acquire infection. The study shows
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 short-term antibody and antigen presence.
