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Proc Biol Sci. 1997 Apr 22;264(1381):553-9.

Adaptive changes in Plasmodium transmission strategies following chloroquine chemotherapy.

Author information

1
Institute of Cell, Animal and Population Biology, University of Edinburgh, UK.

Abstract

Both theory and data suggest that malaria parasites divert resources from within-host replication to the production of transmission stages (gametocytes) when conditions deteriorate. Increased investment into transmission stages should therefore follow subcurative treatment with antimalarial drugs, but relevant clinical studies necessarily lack adequate control groups. We therefore carried out controlled experiments to test this hypothesis, using a rodent malaria (Plasmodium chabaudi) model. Infections treated with a subcurative dose of the antimalarial chloroquine showed an earlier peak and a greater rate of gametocyte production relative to untreated controls. These alterations led to correlated changes in infectivity to mosquitoes, with the consequence that chloroquine treatment had no effect on the proportion of mosquitoes infected. Treatment of human malaria commonly does not result in complete parasite clearance. If surviving parasites produce compensatory increases in their rate of gametocyte production similar to those reported here, such treatment may have minimal effect on decreasing, and may actually increase, transmission. Importantly, if increased investment in transmission is a generalized stress response, the effect might be observed following a variety of antimalarial treatments, including other drugs and potential vaccines. Similar parasite life history counter-adaptations to intervention strategies are likely to occur in many disease-causing organisms.

PMID:
9149425
PMCID:
PMC1688398
DOI:
10.1098/rspb.1997.0079
[Indexed for MEDLINE]
Free PMC Article

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