Land clearing and deforestation mean more mosquito-borne diseases

Sep 8 2008

Australian researchers are blaming land clearing and deforestation for the potential increase in mosquito-borne diseases.

A team from the University of Western Australia (UWA) warn that the rate of mosquito-borne diseases such as Ross River virus will continue to rise unless more careful land clearing practices are adopted.

They have issued a report which highlights the link between deforestation and mosquito-borne disease in patterns.

Researchers Andrew Jardine, Dr. Angus Cook and Professor Philip Weinstein, from UWA's School of Population Health and Dr. Lara O'Sullivan, from UWA's School of Humanities refer to a report by the Food and Agriculture Organization (FAO) of the United Nations in 2005.

That FAO report found that from 2000 to 2005 approximately 13 million hectares of forest were cleared each year, a net loss - after reafforestation and forest expansion - of 7.3 million hectares per annum.

They say the severity of the impact of such large-scale environmental change on human health is only beginning to be quantified, yet the nexus between such change and human health may be traceable back to antiquity.

The team question whether, when it comes to disease and environmental change, humans are slow learners, as reports dating back to Roman Times chart the possible links between deforestation and an increase in malarial disease.

Professor Weinstein says there are many examples from around the world that suggested the experiences of Ancient Rome were being repeated and a growing body of research from Africa, Australia, and the Amazon, points to a connection between mosquito-borne disease rates and ecological changes associated with deforestation.

Professor Weinstein says the evidence is there and it calls for careful management of agricultural clearing and a multidisciplinary approach to policy development on the issue, particularly in regions where there are already indications of escalating disease rates.

In the study an example is given in the form of the impact of land clearing in Western Australia, where deforestation for agriculture has left more than one million hectares of the South West affected by water logging and dryland salinity.

Professor Weinstein says this has had a pronounced impact on the water balance, as the shallow-rooted annual pasture crops use less water than the deep-rooted native perennial vegetation they replace and the resulting increase in recharge and runoff leads to a rise in the water table, bringing saline water to the surface, which vectors such as mosquitoes can exploit.

The research is published in the international science journal BioScience.