Showing papers by "Jefferson A. Vaughan published in 1991"
TL;DR: The low but highly variable numbers of sporozoites transmitted in vitro by mosquitoes used in malaria vaccine challenge studies appears to be a reasonable simulation of natural sporozoite transmission.
Abstract: The frequency and numbers of Plasmodium falciparum sporozoites transmitted in vitro and corresponding sporozoite loads were determined for experimentally infected Anopheles gambiae and An. stephensi. Geometric mean (GM) sporozoite loads in three experiments ranged from 808 to 13, 905 for An. gambiae and from 6, 608 to 17, 702 for An. stephensi. A total of 44.1% of 68 infected An. gambiae and 49.2% of 63 infected An. stephensi transmitted sporozoites in vitro. The GM number of sporozoites transmitted was 4.5 for An. gambiae and 5.4 for An. stephensi. Overall, 86.9% of the mosquitoes transmitted from one to 25 sporozoites, and only 6.6% transmitted over 100 sporozoites (maximum = 369). Sporozoite loads were not a useful predictor of potential sporozoite transmission. Despite higher sporozoite loads, the numbers of sporozoites transmitted in vitro by the experimentally infected mosquitoes were similar to estimates obtained, using the same techniques, for naturally infected An. gambiae in western Kenya. The low but highly variable numbers of sporozoites transmitted in vitro by mosquitoes used in malaria vaccine challenge studies appears to be a reasonable simulation of natural sporozoite transmission.
115 citations
TL;DR: Differences observed in erythrocyte concentration by different anopheline species are consistent with species-specific patterns of host selection and suggest that the fluid produced represents efflux from the filtration of ingested blood.
Abstract: Erythrocyte densities in the blood meals of six Anopheles mosquito species were compared with those of human host erythrocyte densities. During engorgement, An. gambiae Giles and An. stephensi Liston concentrated erythrocytes by factors of 1.8 and 1.7, respectively; An. freeborni Aitken did not concentrate; and An. arabiensis Patton and An. dirus Peyton & Harrison demonstrated an intermediate level of erythrocyte concentration (1.4 and 1.2, respectively). An. albimanus concentrated host hemoglobin, but hemolysis during engorgement decreased bloodmeal erythrocyte density below that of host blood. The degree to which anopheline species concentrated erythrocytes was related to the frequency and time spent undergoing prediuresis (anal excretion of fluid during feeding), suggesting that prediuresis is responsible for erythrocyte concentration and that the fluid produced represents efflux from the filtration of ingested blood. Differences observed in erythrocyte concentration by different anopheline species are consistent with species-specific patterns of host selection.
61 citations