Biodiversity loss and emerging infectious disease: An example from the rodent-borne hemorrhagic fevers

(Uploaded by Plazi for the Bat Literature Project) The relationship between biodiversity loss and emerging infectious diseases is studied in this paper using as examples the rodent-borne hemorrhagic fevers (those caused by hantaviruses and arenaviruses). Both biodiversity loss and infectious disease have taken on importance in the last two decades and both are related to human disturbance of natural systems. Intuitively, one might expect the most diverse natural habitats to support the greatest number of animal diseases that could be transmitted to humans (zoonotic diseases). Yet an examination of the circumstances surrounding outbreaks of rodent-borne hemorrhagic fevers suggests that anthropogenically disturbed, low-diversity habitats present the greatest risk. Two possible mechanisms are suggested to help explain this increased risk. First, disturbed habitats often favor opportunistic/generalist species which happen to be reservoirs for hemorrhagic fever viruses. Second, through a process called the dilution effect, in communities of lowering rodent diversity, more and more virus transmission events (aggressive encounters) occur within a single species, usually an opportunistic species which is the specific host for a hemorrhagic fever virus. The result is more efficient transmission of the virus within the host population, higher prevalence of infection in the host, and greater risk to humans. Results of virus monitoring among rodent populations in the southwestern United States are consistent with predictions of the dilution effect hypothesis. Additional monitoring, sampling, and laboratory experimentation are needed to fully understand the relationship between biodiversity and human disease. This monitoring can be accomplished most effectively through collaboration of scientists from both ecological and public health disciplines.