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Novel Plasmodium falciparum clones and rising clone multiplicities are associated with the increase in malaria morbidity in Ghanaian children during the transition into the high transmission season

Published online by Cambridge University Press:  31 July 2001

A. OFOSU-OKYERE
Affiliation:
Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
M. J. MACKINNON
Affiliation:
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK
M. P. K. SOWA
Affiliation:
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK
K. A. KORAM
Affiliation:
Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
F. NKRUMAH
Affiliation:
Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
Y. D. OSEI
Affiliation:
Department of Biochemistry, University of Ghana, Legon, Ghana
W. G. HILL
Affiliation:
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK
M. D. WILSON
Affiliation:
Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
D. E. ARNOT
Affiliation:
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK

Abstract

A survey of Plasmodium falciparum infection and clone multiplicity in Ghanaian children was carried out to study the effect of the onset of the malaria transmission season on disease incidence. Fortnightly blood samples were collected from 40 children living in the rural town of Dodowa, between February and August 1998. P. falciparum parasite densities were calculated and PCR genotyping was carried out using the polymorphic MSP-1 and MSP-2 genes as target loci for the estimation of the number of parasite clones in each sample. The average clone number was estimated using maximum likelihood techniques and the minimum number of clones per patient was analysed for the effects of age, sex, season, minimum number of clones per child, level of parasitaemia and parasite genotype. The statistical analysis indicated that the more clones a child carried, the more likely they were to have a clinical malaria episode. This was true after adjusting for age and season effects and for the measured circulating parasitaemia. The probability of clinical disease also increased if the MSP-1 MAD 20 and the MSP-2 FC 27 alleles were present. This longitudinal analysis thus indicates that the probability of a Ghanaian child having a symptomatic malaria episode is positively associated with both increasing numbers and novel types of P. falciparum clones.

Type
Research Article
Copyright
2001 Cambridge University Press

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