2004 Fiscal Year Final Research Report Summary
Population genetic analysis of the negative selection of chloroquine resistant Plasmodium falciparum parasites in the absence of antimalarial pressure
| Project/Area Number |
15590375
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Parasitology (including Sanitary zoology)
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| Research Institution | Tokyo Women's Medical University |
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Principal Investigator |
MITA Toshihiro Tokyo Women's Medical University, the Medical Department, Assistant, 医学部, 助手 (80318013)
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| Co-Investigator(Kenkyū-buntansha) |
TSUKAHARA Takahiro Tokyo Women's Medical University, the Medical Department, Assistant, 医学部, 助手 (90328378)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Plasmodium falciparum / chloroquine / resistance / selection / fitness / pfcrt / pfmdr1 |
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| Research Abstract |
In Malawi, the first line drug for treatment of P.falciparum was officially changed from chloroquine to sulfadoxine/pyrimethamine in 1993 because of increasing treatment failure rates that eventually reached 80 %. We previously conducted two drug efficacy surveys in 1998 and 2000 in Salima district in Malawi and found a significant recovery of chloroquine sensitivity both in vitro (3 %) and in vivo (9 %). Concomitant with the recovery of chloroquine sensitivity, the prevalence of the K76T mutation was observed to be substantially lower (9%) than in other African countries where chloroquine use has continued (41-81%). We evidenced that an increased prevalence of the wild type pfcrt haplotype is implicated in the recent recovery of chloroquine sensitivity in Malawi since chloroquine withdrawal. In contrast, we did not see any haplotypes consistent with a K76T→K76 back mutation. Reintroduction of chloroquine as a component drug of combination regimes may be a possible option in places where the complete disappearance of resistant parasites is confirmed.
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