Control of schistosomiasis in Venezuela has been a topic of
major interest and controversy among the metaxenic parasitosis. A
small area of transmission of approximately 15,000 km2
was thought to be eradicated some years ago. However, some
epidemiological characteristics of our transmission area have
limited the success on the way toward eradication. Since 1945, when
the Schistosomiasis Control Program started, the prevalence in the
endemic area has decreased from 14% in 1943 to 1.4% in 1996. Until
1982, the surveillance of active cases was based on massive stool
examination. Since then, the Schistosomiasis Research Group (SRG)
recommended the additional use of serologic tests in the Control
Program and the selective or massive chemotherapy depending on
serological and parasitological prevalence of each community. At
present, the real prevalence is underestimated due to the fact that
approximately 80% of the individuals eliminate less than 100 eggs/g
of feces. Those persons could be responsible for the maintenance of
the foci going on and therefore limiting the impact of the control
measures.
Efforts of the SRG are being oriented toward improvement of
immunodiagnostic tests by using defined antigens (enzymes) and
chemically synthesized peptides, derived from relevant molecules of
the parasite, either for antibodies or antigens search. On the
other hand, introduction of snail competitors has been a biological
weapon in the control of the intermediate host in certain areas.
However, the recent reinfestation of water courses by
Biomphalaria glabrata, the increased prevalence in some
areas, together with important administrative changes at the
Control Program of the Minister of Health, have arisen new
questions and doubts, challenging the eradication strategy proposed
during the last decade.