Mumbai – is transmission season increasing?

The Times of India reports that, “Malaria is no longer restricted to just monsoon months as in the past. Spurred on by widespread construction activity and the resulting poor sanitation, the disease has becomes a round-the-year feature in Mumbai, killing less people but afflicting more.”

An increase was noted: “In all, 76,755 contracted the ailment in 2010, 74% more than the 2009’s figure of 44,035,” but with fewer deaths (better case management?), but it is not clear whether these cases were parasitologically diagnosed.

A member of the medical association attributes the increase, especially the off-season rise, to human activity – construction projects. The official stated that, “Construction sites have puddles of water in which mosquitoes breed. Since construction work goes on throughout the year, so does the breeding. This obviously increases the incidence of malaria.”

Worry was also expressed about, “resistance developed by the Anopheles albimanus mosquito that the civic body’s insecticide fumigation has no effect on it.” This has led the city to consider using “bacillus thuringiensis variety israelensis” for control.

Ironically, in pointing out that, “Another reason for the spread of malaria, which is caused by a parasite called plasmodium, during non-monsoon months is that plasmodium can stay in the body for a long period,” the article raises the possibility that the upswing may not be fully due to new transmission.

asia-in-wmr-2008.gifAside from these possible limitations on the validity of the data,  the potential for increased transmission is worrisome, especially in a part of the world that has received less (but increasing) attention from the Roll Back Malaria Partnership. The map from the 2008 World Malaria Report shows the extent of the problem in Asia.

India has a double problem with malaria, hosting both P. vivax and P falciparum.  A recently published article reports that while the national control program has introduced artemisinin-based combination therapy for P. falciparum as a first-line treatment, the older drugs, chloroquine (CQ) and Sulphadoxine-Pyrimethamine (SP) are still available. Unfortunately Shrabanee Mullic and colleagues found that, “In Jalpaiguri District the overall failure rate of CQ was 61% and of SP 14%, which was well above the WHO recommended cut-off threshold level (10%) for change of drug policy.”

Other research in India examined vector control with positive effects. “A study was conducted to evaluate the preventive efficacy of insecticide-treated mosquito nets (ITMNs) and mosquito repellent (MR) in a malaria-endemic foothill area of Assam, India, with forest ecosystem.” The researchers found that, “The total vector population in the three intervention sectors decreased significantly compared with that of the non-intervention one.”

Overall, malaria in India is a complex phenomenon with different forms of the parasite, different ecological settings and different levels of government involved. More attention is needed to address this complex situation is malaria is ever to be eliminated.

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