John C. Beier

Malaria transmission potential of Anopheles mosquitoes in the Mwea‐Tebere irrigation scheme, Kenya

Abstract. 1. Anopheles arabiensis Patton and An.funestus Giles were identified as vectors of Plasmodium falciparum malaria in the Mwea‐Tebere irrigation scheme, Kenya. An.arabiensis was the only member of the An.gambiae complex identified from chromosome characteristics. Other Anopheles species found included An.pharoensis Theobald, An.rufipes Gough and An.coustani Laveran.

Quantitation of malaria sporozoites transmitted in vitro during salivation by wild Afrotropical Anopheles

Abstract. The malaria transmission potential of wild, infective Anopheles from western Kenya was evaluated by determining the number of sporozoites transmitted in vitro by salivation when their mouthparts were inserted into capillary tubes containing either sucrose or blood. With sucrose, 86.6% of 102 infective Anopheles transmitted a geometric mean (GM) of 3.84 sporozoites (range 1–34). With blood, 23.1% of 104 infective Anopheles, tested on the day of collection, transmitted a GM of 2.30 sporozoites (range 1–117). For Anopheles held 5 days postcapture before testing with blood, 53.6% of 56 transmitted a GM of 6.04 sporozoites (range 1–420). Transmitting Anopheles contained significantly more salivary gland sporozoites than non‐transmitters. No significant differences were detected between Anopheles gambiae Giles sensu lato and Anopheles funestus Giles in sporozoite transmission by individuals with sporozoites in their salivary glands.

ELISA absorbance cut‐off method affects malaria sporozoite rate determination in wild Afrotropical Anopheles

ABSTRACT. Malaria sporozoite infection rates in a mixed species group of 244 Anopheles gambiae Giles sensu lato and 115 An. funestus Giles wild female mosquitoes were compared using three methods to determine cutoff absorbance values for positivity of a Plasmodium falciparum Welch enzyme‐linked immunosorbent assay (ELISA). Positive controls were based on P. falciparum circumsporozoite protein. As negative controls, four wild male Anopheles were included on each microtitre plate; tests were repeated on four consecutive days for each plate.

Quantitation of malaria sporozoites in the salivary glands of wild Afrotropical Anopheles

Abstract. The number of malaria sporozoites in the salivary glands was determined microscopically for 1137 wild, naturally infected Anopheles from western Kenya. Infective Anopheles gambiae Giles sensu lato (n=874) contained a geometric mean (GM) of 962 sporozoites and An.funestus Giles (n=263) contained 812. No significant differences were detected in geometric mean numbers of sporozoites between species, collection techniques or sites.

Anatomical dissemination of circumsporozoite protein in wild Afrotropical Anopheles affects malaria sporozoite rate determination by ELISA

Abstract. The head, thorax, wings, legs and abdomen of 320 wild‐caught Anopheles gambiae Giles sensu lato and 115 An.funestus Giles were tested by an enzyme‐linked immunosorbent assay (ELISA) for Plasmodium falciparum Welch to determine how anatomical dissemination of circumsporozoite (CS) protein could affect the estimation of malaria sporozoite rates by ELISA. Of fifty‐three Anopheles with CS protein detected in any body part, positive reactions were observed for 58.5% of heads, 67.0% of thoraces, 39.6% of wings, 52.8% of legs and 60.4% of abdomens. Mean absorbance values (range 0–2.00) were highest in thorax samples (1.17), followed by heads (0.80), abdomens (0.67), wings (0.48) and legs (0.46).