Economic solution to scourge of malaria

Johannesburg ó THE United Nations Framework Convention on Climate's 9th Conference of Parties has just ended in Milan. The multimillion-dollar conference did not achieve much, and the future of the Kyoto Protocol is in doubt and depends on Russia ratifying it.

To the glee of climate sceptics and horror of the Greens, Russia probably will not. This means that the many parties with vested interests in the protocol will stress every possible histrionic climate change scenario in order to boost the political will to ratify the protocol. One such favourite claim states that climate change will lead to the rapid spread of vector-borne diseases, such as malaria, yellow fever and dengue, to new areas. This claim, however, slithers through scientific fact.

Some clear and obvious links between climate and the spread of mosquito-borne disease exist. If it rains more, more breeding pools for mosquitoes will develop. Thus, diseases could spread faster. For this reason, researchers in southern Africa monitor some climate data to prepare for possible epidemics. Yet climate and disease have an immensely complex relationship. One cannot extrapolate disease predictions on simple climate data.

As anyone who has tried to kill one at 2am knows, mosquitoes are wily. When temperatures rise, they rest in the cool indoors, venturing outdoors when the heat lessens. During cold snaps, they find warm resting places, such as sewers or storm drains. Malaria-transmitting Anopheles mosquitoes can survive the extremes of a Sudanese summer when outdoor temperatures exceed 55∞C. Adult Culex pipiens, a carrier of West Nile virus, can winter in North Dakota, when the temperatures average -18∞C to -9∞C.

Depending on where mosquitoes breed, increased rainfall can create more breeding pools, or it can flush out breeding sites, reducing the vector population.

As temperatures increase, the life cycles of the mosquito and of the malaria parasite speed up. However, this may not necessarily increase disease transmission.

Laying eggs and feeding are high-risk activities that can reduce mosquito survival rates. If the life cycle of the parasite outpaces the life cycle of the mosquito, no disease transmission takes place.

Moreover, when studying climate and vector-borne disease transmission, you must consider the past few thousand years. Dr Paul Reiter of the Pasteur Institute in Paris points out in a new book Adapt or Die: the Science, Politics and Economics of Climate Change, edited by Kendra Okonski that in the past 2000 years, malaria thrived during temperature extremes. During the dark ages (from 750 to 1100 AD) temperatures were so low that the Nile froze and ice floated in the Adriatic Sea. During the Middle Ages, temperatures rose, so much so that Greenland became suitable for agriculture and England became a wine producing region. Yet all the while the transmission of malaria and other vector-borne diseases continued.

As temperatures plummeted during the dark ages and during the little ice age of the 16th century, malaria continued to flourish in Europe. It disappeared only when Europeans became wealthy enough to afford medication, decent housing and the drainage of swamps for agricultural land. Studies have found also that the increased incidence of malaria in Kenya's western highlands correlates not with climate changes, but mostly with population movements, failing drugs and a lack of adequate malaria control.

As the worst enemy of the Anopheles mosquito and Plasmodium parasite is a wealthy population, we should support Russia's decision to concentrate on economic growth by not ratifying the Kyoto Protocol. In fact we should be encouraging all malarial countries to do the same.

Tren is a director of the health advocacy group Africa Fighting Malaria.