Effects of habitat change on avian blood-borne pathogens

Ravinder Sehgal

San Francisco State University, USA

The effects of deforestation on health are diverse and are becoming increasingly apparent with the highly publicized recent outbreaks of several diseases spread to humans by animals. Here, we conduct a study of the effects of deforestation on the spread of blood parasites in African rainforest birds. Over the past 17 years, scientists at the Center for Tropical Research have collected more than 10,000 individual blood samples from over 200 rainforest bird species in a variety of habitats across Central and West Africa. Significantly, the samples were collected from sites both before and after habitat degradation, permitting a unique examination of the direct effects of human-induced habitat alterations. Using complementary techniques of blood smear analysis and molecular biology, samples are assayed for Plasmodium, Haemoproteus, Leucocytozoon and Trypanosoma. We have obtained results regarding the host-specificity, prevalence and lineage diversity of these parasites in rainforest birds. As part of the larger project, we collected blood samples from two bird species from eight paired disturbed and undisturbed sites in Southern Cameroon. Linking DNA sequence lineages with identified parasite morphospecies, we describe significant differences in prevalence between habitat types in the haemosporidian parasites. We incorporate satellite imagery data to quantify differences among the sites and predict how changes in forest composition may affect the spread of diseases. With the combined information, we have developed models to help predict how deforestation will influence future disease outbreaks, thus facilitating the development of reforestation strategies.

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