Tuesday, August 30, 2011
There is an interesting conflict between the findings of two different pieces of malaria research. One piece from Tanzania claims that mosquito numbers have decreased over a number of years to such an extent that fewer and fewer people are being infected.
Whereas scientists in Kenya agree, but claim that malaria infections are lower because of public health measures, such as "well-managed control programmes which involved distribution of nets, effective medicines and vector suppression".
It looks as if there will have to be a meta-study to resolve the issue: has malaria declined because of successful public health measures, because malaria spreading mosquitos are in decline (for one or more reasons), or is malaria prevalence merely cyclical, as has been found with some other diseases?
The Tanzanian-Danish study is adamant that the decline in malaria is not attributable to human interventions, apparently. This conclusion is unlikely to be popular among public health donors, who tend to attribute success to their efforts and failures to something that can remain quite mysterious.
Rumors about the possible influence of climate change have arisen, predictably, but that's a pretty amorphous determinant, at best. But, as scientists, they have to say something.
Despite the claims about distribution of nets in countries such as Kenya and Tanzania, I have talked to many who do not have nets, do not have enough nets, can't afford insecticide treated nets, or don't live in conditions that make nets useful, for example, they don't sleep in a bed or share the bed with so many people the net is useless.
Other articles have mentioned the fact that nets are often used for things far removed from their intended purposes. And so called 'free' nets are often sold, sometimes at too high a cost for the most needy.
And when it comes to drugs, there have been many articles lately, bemoaning the fact that 'fake' drugs (a term that fails to distinguish between generic versions of drugs, counterfeits and placebos) are responsible for sickness, death and resistant strains of malaria. Clearly, the drug industry wants public money to be used to ensure that they extract as much as they can from those living in the greatest poverty.
So all these scientists and experts really do have themselves in a tangle. Declines in numbers of mosquitoes have been equally sharp in villages without mosquito nets, though some articles would make you think there was no such thing as a village that didn't have nets.
Interestingly, a long way from East Africa, insecticide resistance has been linked to an increase in malaria in Senegal. Apparently, mosquitoes have become resistant to the insecticide used on bednets and malaria incidence is now higher than it was before the reduction campaign.
In addition to resistance in the mosquitoes, older children and adults are becoming more susceptible to the disease, which is an entirely separate matter. People's immune response is increased by frequent exposure to malaria, but it then drops once exposure is reduced. This research also acknowledges that the increase in the disease had been forseen for some time.
Sometimes these 'vertical' public health programs, ones that aim to address only one disease, seem a bit futile. For example, attempts to eradicate polio by using an improved vaccination without improving people's living conditions, especially their access to clean water and good sanitation, seem like a bit of a loser.
Similarly with malaria, many people who are most at risk from malaria live in areas with a lot of stagnant water and little control over waste disposal. The same people risk numerous water borne, hygiene related and other diseases, not just the economically viable ones. Perhaps the obsession with technical fixes, yet again, is getting in the way of providing people with what is vital for their survival and their health: decent living conditions.