Malaria entomological inoculation rates in western Venezuela

Over 61 000 anophelines collected between January 1988 and October 1989 in three villages in western Venezuela were assayed by ELISA for Plasmodium vivax circumsporozoite (CS) protein. The six specimens confirmed positive belonged to three species: Anopheles ( Nyssorhynchus) nuneztovari Gabaldón, 1940, A. albitarsis Arribalzaga, 1878 sensu lato and A. oswaldoi (Peryassu, 1922). The estimated CS protein rate for all species combined was 0.01% (95% confidence limits 0.004-0.02%). This CS protein rate and the mean number of bites received by the collectors indicated a sporozoite inoculation rate of about 10.5 infective bites per person per year. From this value and the number of human malaria cases reported it was estimated that only 0.32% of bites by CS-positive mosquitoes led to a malaria infection. The CS protein rate is so low that this parameter would not be a practical indicator of the efficacy of control campaigns in this area.