Field Evaluation of an Enzyme-Linked Immunosorbent Assay (Elisa) for Plasmodium falciparum Sporozoite Detection in Anopheline Mosquitoes from Kenya

Abstract

An enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody that recognizes a repetitive epitope on the circumsporozoite protein of Plasmodium falciparum was used in Kenya to assess malaria infections in Anopheles gambiae s.l. and An. funestus. The ELISA confirmed that 88% of 44 sporozoite-positive gland dissections were P. falciparum. The ELISA infection rate of 18.6% (n = 736) for individually tested mosquitoes for both species was significantly higher than the 10.4% (n = 537) salivary gland sporozoite rate determined by dissection. This difference was due to ELISA detection of medium and large sized oocysts on the midguts of infected mosquitoes which did not contain salivary gland sporozoites. From a series of 379 Anopheles that were cut at the thorax, ELISA tests on "head" and "body" portions showed that 29.5% of 95 positive mosquitoes contained circumsporozoite antigen in the body portion in the absence of salivary gland infections. This field evaluation demonstrates that the ELISA can most accurately be used to estimate sporozoite rates by cutting mosquitoes at the thorax and testing anterior portions.

Seasonal density, sporozoite rates and entomological inoculation rates of Anopheles gambiae and Anopheles funestus in a high‐altitude sugarcane growing zone in western kenya

“…The head and thorax of each mosquito was carefully separated from the abdomen and tested for the presence of P. falciparum circumsporozoite protein (CS) as described by Beier et al (1987). Briefly, mosquitoes were ground individually in 50 l boiled casein containing Nonidet 40 and final volume brought to 250 l with blocking buffer.…”

Naturally Acquired Immune Responses to Plasmodium falciparum Sexual Stage Antigens Pfs48/45 and Pfs230 in an Area of Seasonal Transmission

“…The CDC light trap was placed close to the bed of the sleeper in randomly selected houses, and mosquito capture was done from 7:00 p.m. to 6:00 a.m. Mosquito species were identified morphologically, counted, and stored in tubes with silica gel. A representative sample of Anopheles gambiae mosquito thoraces and heads were examined to obtain a P. falciparum circumsporozoite protein (CSP) positivity index using a routine CSP enzyme-linked immunosorbent assay (ELISA) (2). The monthly sporozoite rate was estimated by testing representative samples (approximately 50% of all mosquitoes caught from each trap) of randomly selected specimens of mosquitoes from each village.…”

Integrated malaria vector control with microbial larvicides and insecticide-treated nets in western Kenya: a controlled trial

“…were identified to the species level using polymerase chain reaction, and the presence of sporozoites was determined by enzymelinked immunosorbent assay (ELISA) of pooled samples of 10 mosquitoes per test. 34,35 Malaria parasitaemia The incidence of new parasite infections was measured during the long rains (April-June) and short rains (November-January) each year, when transmission was likely to be highest. On each occasion two surveys were carried out 2 months apart.…”