Halting Malaria

Health Minister Manto Tsabalala-Msimang has drawn much criticism for what, at times, appear to be irrational actions.   One such action is the continued use of the maligned insecticide DDT to combat malaria.

The use of DDT in combination with effective drug therapy for malaria patients has kept the disease under control since 1946.

The department’s strategy is simple but effective.  The life cycle of the malaria parasite must be interrupted in each of its two hosts.  This is achieved by placing a barrier betweens humans and the malaria vector, the anopheles mosquito, and by isolating infected people from the mosquitoes.  The barrier is created by the residual spraying f people’s homes with DDT and, to a lesser degree, the use of a benign larvacide on open water.

The isolation of patients from mosquitoes is achieved by administering an effective drug when some of the parasite population in an infected human changes its reproductive strategy from asexual to sexual – the state at which humans transmit the parasite to mosquitoes.

The key to the process is DDT.  No other insecticide has proven as effective against mosquitoes.  In some malaria areas, DDT has been so effective that spraying could be spotted altogether and only restarted after heavy rains.  Importantly DDT is cheap, easy to produce and it lasts a long time.

The problem with DDT is that, in an increasingly environmentally conscious world, it has become the catch-all example for the ecological disasters humans have visited upon the planet.  In 1962, Rachel Carson’s book, The Silent Spring, raised such a scare that people ignored the science and react irrationally at the proposed use of DDT to this day.  What was particularly scary was the discovery that DDT accumulates in the adipose tissue of humans and animals, and its metabolites remain and accumulate in the food chain. 

However, after almost 60 years of constant use, no scientific study has managed to prove the predicted and exaggerated harmful effects of DDT on human life.  In contrast, the indicators for sustained drastic action against the disease are clearly illustrated.  Globally, malaria infects between 300 million and 500 million people a year.  More than a million of them die, mostly children.  In SA, about 10% of the population lives in malaria areas.

The costs – in human lives and in economic terms – are enormous and the potential cost of an unchecked rate of infection would be disastrous.  When SA stopped using DDT in 1996, the rate of infection rose rapidly.  In KwaZulu-Natal, which was worst affected, the number of cases rose from about 8 000 in 1996 to nearly 42 000 in 2000 at the height of the epidemic.  The health department’s resumption of residual spraying programmes, combined with effective treatment of patients, has brought the disease under control in SA.

This does not mean that the struggle is won or that we are safe.  The increase in trade and traffic across southern Africa has rough infectious individuals across our borders from countries like Zambia, where infection is out of control.  This means SA will be fighting a never-ending battle unless infection rates are brought under control in the rest of our region.

Although the fight against malaria may be in the interest of the whole world, the institutions charged with the responsibility- the World Health Organisation among others – have failed to carry it out, and we should not expect their policies to change any time soon.  We have to do this ourselves and the way to do it is to strengthen the hand of the health minister who, along with Swaziland, leads southern Africa in the battle.

If it means SA must provide its neighbours with DDT, and the training in its appropriate and safe use, then we must do it – not just for the neighbours, but for ourselves.

Business Day