TY - JOUR

T1 - Effect of gametocyte sex ratio on infectivity of Plasmodium falciparum to Anopheles gambiae

AU - Robert, V.

AU - Read, A. F.

AU - Essong, J.

AU - Tchuinkam, T.

AU - Mulder, B.

AU - Verhave, J. P.

AU - Carnevale, P.

N1 - Funding Information:
Acknowledgements We thank Richard Carter.G astonP ichon, Ben Sheldona nd Louise Groves for readingf he manuscripta nd making useful remarks.F inancial support was provided by ORSTOM, OCEAC, the EuropeanC ommunity (STD3)a,n d the French Ministry of ResearchA. . Readw asf undedb y a BBSRC AdvancedR esearch Fellowship.

PY - 1996

Y1 - 1996

N2 - Insectary-reared Anopheles gambiae were experimentally fed with the blood of 90 naturally infected human volunteers carrying gametocytes of Plasmodium falciparum. At least one mosquito was successfully infected in 74% of experiments. The probability that a gametocyte carrier was infective, the probability that a mosquito became infected, and the number of oocysts harboured were related to gametocyte density. The mean proportion of male gametocytes was 0.217 (i.e., 3.6 females for every male). Sex ratios differed significantly between gametocyte carriers. Variation in sex ratio was not related to the probability that a gametocyte carrier was infective. Among infective people whose sex ratio estimates were based on a reasonable number of gametocytes, sex ratio significantly predicted the proportion of infected mosquitoes and mean oocyst load, with infectivity rising as the proportion of male gametocytes increased towards 50%. There was no indication that infectivity reached a peak at some intermediate sex ratio, as would be expected if random mating of gametes was the primary determinant of fertilization success. These results raise 2 interesting questions: why should higher sex ratios be more infective, and why is the observed population sex ratio lower than that: which produces the greatest infectivity?.

AB - Insectary-reared Anopheles gambiae were experimentally fed with the blood of 90 naturally infected human volunteers carrying gametocytes of Plasmodium falciparum. At least one mosquito was successfully infected in 74% of experiments. The probability that a gametocyte carrier was infective, the probability that a mosquito became infected, and the number of oocysts harboured were related to gametocyte density. The mean proportion of male gametocytes was 0.217 (i.e., 3.6 females for every male). Sex ratios differed significantly between gametocyte carriers. Variation in sex ratio was not related to the probability that a gametocyte carrier was infective. Among infective people whose sex ratio estimates were based on a reasonable number of gametocytes, sex ratio significantly predicted the proportion of infected mosquitoes and mean oocyst load, with infectivity rising as the proportion of male gametocytes increased towards 50%. There was no indication that infectivity reached a peak at some intermediate sex ratio, as would be expected if random mating of gametes was the primary determinant of fertilization success. These results raise 2 interesting questions: why should higher sex ratios be more infective, and why is the observed population sex ratio lower than that: which produces the greatest infectivity?.

UR - http://www.scopus.com/inward/record.url?scp=0030477928&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030477928&partnerID=8YFLogxK

U2 - 10.1016/S0035-9203(96)90408-3

DO - 10.1016/S0035-9203(96)90408-3

M3 - Article

C2 - 9015496

AN - SCOPUS:0030477928

SN - 0035-9203

VL - 90

SP - 621

EP - 624

JO - Transactions of the Royal Society of Tropical Medicine and Hygiene

JF - Transactions of the Royal Society of Tropical Medicine and Hygiene

IS - 6

ER -