Mixed news on malaria

10 Sep 2009

Paul Chinnock

Source: TropIKA.net

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A Ugandan father and his sick child. Sadly, the bednet they are using is an old one and has not been treated with insecticide.
© William Daniels.

Recent developments on malaria present a mixed picture. Against encouraging new findings on the effectiveness of control strategies, must be set some serious concerns.

Further confirmation of cost effectiveness of insecticide treated bednets (ITNs) has been provided by a study in the Democratic Republic of Congo, in which ITNs were given to nearly 18,000 mothers at prenatal clinics. Researchers concluded that the nets prevented both an estimated 414 infant deaths from malaria and an estimated 587 low birth weight deliveries. The study’s lead author Dr Sylvia Becker-Dreps told UPI that, “This is an extremely cost-effective intervention. In fact, it approaches the cost effectiveness of measles vaccination”. (The study is published in the American Journal of Tropical Medicine & Hygiene.)

The use of netting to screen entries to homes in malaria-endemic regions has also been proposed as a way of reducing exposure to mosquito bites. A new study in The Gambia (involving some 500 homes that already had ITNs) examined the use of screening of eaves and ceilings and of “full” screening (eaves, ceilings, windows and doors). Both reduced the number of mosquitoes in the houses, with full screening achieving the higher reduction. The frequency of parasitaemia in children did not differ between the intervention and control groups, but the researchers postulate that house screening could contribute to prevention of anaemia in children. (The study is published in the Lancet; see also a smaller study highlighted on TropIKA.net in May.)

Of course new approaches to keep mosquitoes at bay are still welcome and there has been further progress in attempts to find chemicals that could be used to disrupt the way in which mosquitoes “smell” their human victims. (See news report.)

With the wealth of evidence on the effectiveness of ITNs now available it is not surprising that efforts to distribute ITNs continue to grow – see for example a recent story in The East African. Confidence in what can be achieved through ITN distribution is also one reason why several African governments have now stated that they are optimistic that they will be able to eliminate malaria as a public health problem in the not-too-distant future. Examples include Kenya and Tanzania, which has set 2015 as its target date for elimination.

The prospects for elimination were also discussed by at the annual meeting of WHO’s African Regional Office (AFRO). The meeting called on member states to “...integrate malaria control in national development plans and poverty reduction strategies, support ongoing research and development initiatives, strengthen national health information systems, and invest more in health promotion, community education and participation”.

But is elimination a realistic goal, given – in particular – the concern over the appearance of resistance to artemisinin, now the recommended treatment for malaria? And can we really be confident that the package of interventions now used against the disease is as effective as has been claimed? A recent commentary in Malaria Journal argues that caution is required when using health facility-based data to evaluate the health impact of malaria control efforts in Africa.

Africa, of course, is not the only part of the world blighted by malaria – a fact that sometimes seems to be forgotten. India’s malaria burden, particularly in its urban centres, may be increasing; Mumbai is one city that has reported a rise in case numbers – see news report.

With all public health interventions there is the concern that richer members of society will benefit more than the poor, who are the most vulnerable to disease. A study from Nigeria, reported in BMC International Health and Human Rights, has confirmed that while malaria is a burden to all socio-economic groups, the poor are more affected because a greater proportion of their financial resources are spent on treating the disease.

Efforts to control malaria are hampered by the fact that there is still so much we do not yet know about this disease. Indeed there are a lot of “unknown unknowns” in malaria. There could, for example, be more types of malaria than we thought. It was believed that Plasmodium knowlesi could cause malaria only in monkeys but more recent findings have shown it to be responsible for many human cases of malaria in Malaysia. A new study (in Clinical Infectious Diseases) confirms that knowlesi malaria can cause a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately one in 10 patients develop potentially fatal complications.

And there are malarial mosquito species that we did not know about. South African researchers have identified a new Plasmodium species that they believe is of major significance as a vector of malaria – see study published in The American Journal of Tropical Medicine & Hygiene and also IRIN news report.

It is also clear that disasters – natural or man-made – can easily put malaria control efforts off-track – see recent reports on the impact of flooding in West Africa and war in Sudan.

Realism is needed in the continuing battle against malaria. Elimination may be possible but we must be prepared for setbacks along the way.