Deforestation in Costa Rica has been found to increase the risk of cattle becoming infected with rabies by vampire bats, according to a study published in Emerging Infectious Diseases by disease ecologists at Emory University. The destruction of tropical forests leads to a decrease in diversity, changing disease transmission dynamics and potentially leading to the emergence of new pathogens or the reemergence of existing ones. While Costa Rica has a significant portion of its territory protected under its National System of Conservation Areas to support ecotourism, agriculture, especially livestock farming, encroaches into unprotected tropical forest areas.
The Costa Rican government has been successful in protecting much of its tropical forests, but high rates of deforestation persist in some areas due to land clearance for agricultural purposes. One study found that rabies outbreaks in cattle in Costa Rica were linked to the location of forest habitats, with each kilometer increase in distance from the forest increasing the probability of an outbreak by 4%. Vampire bats, found in tropical and subtropical areas of Central and South America, spread the virus to cattle through bites. The researchers mapped the time and locations of rabies outbreaks in cattle from 1985 to 2020 in both northern and southern regions where tropical forests have been cleared for agriculture.
The study showed a correlation between forest habitats and rabies outbreaks, indicating that decreased availability of bat-roosting sites within forested areas leads to vampire bats feeding on cattle rather than wild mammals. The highest probability of rabies outbreaks was found in Puntarenas Province in the south, signaling the need for specific preventative measures in that region to prevent rabies reemergence in humans. Similar patterns linking the destruction of tropical forests with disease reemergence have been observed in other regions, such as the reemergence of hanta viruses in the Amazon and the Lassa virus in West Africa linked to human land-use changes.
The researchers emphasize the importance of considering disease emergence when making decisions about large-scale land-use changes, as these changes can lead to disease reemergence and increased greenhouse-gas emissions. Cows and other ruminant animals emit methane, a potent greenhouse gas, as they digest grasses, contributing to climate change. Governments and individuals are encouraged to reduce beef consumption to promote both personal health and environmental sustainability. The study was conducted by researchers at Emory University and funded by various institutions including Emory’s Halle Institute for Global Research and the Fulbright Association.