Association of house spraying with suppressed levels of drug resistance in ZimbabweReport as inadecuate




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Malaria Journal

, 3:35

First Online: 18 October 2004Received: 14 July 2004Accepted: 18 October 2004

Abstract

BackgroundPublic health strategies are needed to curb antimalarial drug resistance. Theoretical argument points to an association between malaria transmission and drug resistance although field evidence remains limited. Field observations, made in Zimbabwe, on the relationship between transmission and multigenic drug resistance, typified by chloroquine, are reported here.

MethodsPeriodic assessments of the therapeutic response of uncomplicated falciparum malaria to chloroquine in two selectively sprayed or unsprayed health centre catchments, from 1995 – 2003. Cross-sectional analysis of in vivo chloroquine failure events for five sites in relation to natural endemicity and spraying history.

ResultsDuring selective house spraying, the chloroquine failure rate for the sprayed catchment decreased, such that, after four years, the odds of chloroquine failure were 4× lower than before start of spraying in the area OR 0.2, 95% CI 0.07 – 0.75, p = 0.010, n = 100. Chloroquine failure odds for the sprayed area became 4× lower than contemporaneous failure odds for the unsprayed area OR 0.2 95% CI 0.08 – 0.65, p = 0.003, n = 156, although the likelihood of failure was not significantly different for the two catchments before selective spraying started OR 0.5, 95% CI 0.21 – 1.32; p = 0.170, n = 88. When spraying ended, in 1999, the drug failure odds for the former sprayed area increased back 4 fold by 2003 OR 4.2, 95%CI 1.49 – 11.78, p = 0.004, n = 146. High altitude areas with naturally lower transmission exhibited a 6× lower likelihood of drug failure than low-lying areas OR 0.16 95% CI 0.068 – 0.353 -2 log likelihood change 23.239, p < 0.001, n = 465. Compared to sites under ongoing annual spraying, areas that were last sprayed 3–7 years ago experienced a 4-fold higher probability of chloroquine failure OR 4.1, 95%CI 1.84 – 9.14 -2 log likelihood change 13.956, p < 0.001.

ConclusionReduced transmission is associated with suppressed levels of resistance to chloroquine and presumably other regimens with multigenic drug resistance. It seems the adoption of transmission control alongside combination chemotherapy is a potent strategy for the future containment of drug-resistant malaria.

Electronic supplementary materialThe online version of this article doi:10.1186-1475-2875-3-35 contains supplementary material, which is available to authorized users.

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Author: Sungano Mharakurwa - Susan L Mutambu - Robert Mudyiradima - Tawanda Chimbadzwa - Steven K Chandiwana - Karen P Day

Source: https://link.springer.com/



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