TY - JOUR

T1 - Diversity of Plasmodium falciparum populations and complexity of infections in relation to transmission intensity and host age: a study from the Usambara Mountains, Tanzania

AU - Bendixen, M.

AU - Msangeni, H.A..

AU - Pedersen, Bo Vest

AU - Shayo, D.

AU - Bødker, René

PY - 2001

Y1 - 2001

N2 - Diversity and complexity of infections with Plasmodium falciparum were described from cross-sectional surveys in November–December 1996 in 6 villages in the Usambara Mountains, Tanzania, where transmission ranged markedly from 0·03 to 91 infective bites per individual per year. Forty-eight samples, stratified for age and parasite densities, were examined from each village (n = 288). Genotyping was performed by a nested PCR method using primers specific for allele families of genes for the merozoite surface protein 1 (msp-1) and merozoite surface protein 2 (msp-2). A high degree of genetic diversity was found within each village but there were no differences found among the 6 villages. Poisson regressions showed significant effects of host age, village and interaction between host age and village on the complexity of infection. There was a positive, non-linear relationship between complexity of infection and transmission intensity with a maximal number of genotypes found per individual even at high transmission intensities. Furthermore there was a significantly lower complexity found in adults (>15 years) as compared to children (<15 years) in the lowland village. This difference was not found as transmission intensity decreased. By comparing data from the same geographical area, using the same methods, and taking into account confounding factors, the present study provides evidence for an effect of both age and transmission intensity on complexity of infection with P. falciparum.

AB - Diversity and complexity of infections with Plasmodium falciparum were described from cross-sectional surveys in November–December 1996 in 6 villages in the Usambara Mountains, Tanzania, where transmission ranged markedly from 0·03 to 91 infective bites per individual per year. Forty-eight samples, stratified for age and parasite densities, were examined from each village (n = 288). Genotyping was performed by a nested PCR method using primers specific for allele families of genes for the merozoite surface protein 1 (msp-1) and merozoite surface protein 2 (msp-2). A high degree of genetic diversity was found within each village but there were no differences found among the 6 villages. Poisson regressions showed significant effects of host age, village and interaction between host age and village on the complexity of infection. There was a positive, non-linear relationship between complexity of infection and transmission intensity with a maximal number of genotypes found per individual even at high transmission intensities. Furthermore there was a significantly lower complexity found in adults (>15 years) as compared to children (<15 years) in the lowland village. This difference was not found as transmission intensity decreased. By comparing data from the same geographical area, using the same methods, and taking into account confounding factors, the present study provides evidence for an effect of both age and transmission intensity on complexity of infection with P. falciparum.

U2 - 10.1016/S0035-9203(01)90140-3

DO - 10.1016/S0035-9203(01)90140-3

M3 - Journal article

SP - 143

EP - 148

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

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

SN - 0035-9203

IS - 95

ER -