16 November 2010 - The spectacular growth in world population since the 18th century - and particularly during the 20th century, when it almost quadrupled- is obviously one of the principal causes of radical change in the relationship between animal populations, human civilization and the ecological system of the earth. Population growth along with human encroachment of forests and wildlife reserves, among other factors, have provoked massive killing of wild animals for subsistence or commercial purposes throughout the humid tropics of the Americas, Asia, and Africa (most pronouncedly in West and Central Africa). This short web article looks at the hunting of bats for bushmeat and examines the implication for global public health.
The extent of hunting of bats for bushmeat in the Old World tropics is widespread. Given that over 20 percent of all mammal species are bats, they are assiduously sought as a source of food in areas where food production remains challenging. Studies and literature reviews by wildlife experts report high levels of off take throughout Asia, the Pacific islands and some Western Indian Ocean islands, where fruit bats of the genus Pteropus are eaten extensively. In the African continent, most hunting was reported in western states. The largest fruit bat Eidolon helvum was preferred, but others exotic species were also hunted for food (and trade). In Asia, insectivorous bats are also eaten, particularly Tadarida, among others.
The hunting of bats is both for local consumption and commercial purposes. Also in many countries bats are not eaten, but killed indiscriminately because of fear or hatred of the species. This high level of offtake has had an impact on global bat populations and has resulted in the local extinction of some species. This creates profound effects on ecology and agriculture because in some areas bats may be "keystone species" in ecosystems as pollinators and seed dispersers of plants, many of which are economically important.
In addition to concerns related to the decimation of bat populations in specific locations, there is also the fear that increased contact between bats and humans from encroachment, including hunting, may lead to higher incidences of old and new diseases. Approximately 60 percent of emerging infectious diseases of humans are zoonotic, that is, those diseases that are transmitted from animals to humans. Of these, 72 percent originate from wildlife; these include Anthrax, Ebola, Hendra, HIV/AIDS, monkey pox, Nipah, rabies, severe acute respiratory syndrome (SARS), simian foamy virus and West Nile virus.
The Food and Agriculture Organization of the United Nations (FAO) is currently undertaking a bat behavior and surveillance study that examines bat ecology and potential interfaces with livestock systems and human populations. It is important to recognize that the drivers behind bat-borne infectious diseases are a result of encroachment, demographics, landscape changes and other anthropogenic activities. Potential pathogens have likely existed for hundreds, if not thousands of years, but pathogen introduction into different species is a phenomenon which has recently emerged due to increasing contact among bats, people and livestock.
Bat-borne disease incidences appear to be on the rise as agricultural expansion and natural resource extraction activities push forward into bat occupied territories, thus increasing the interaction between bats, livestock and people. The hunting of bats is a high-risk activity for pathogen exchange as viruses can easily spread via bites and scratches when handling bats or through body fluids when processing carcasses for consumption. Understanding the changes impacting these populations is critical to design effective management tools to address identified risks and limit the exchange of viruses between species.
A deeper comprehension of bat ecology and the ecosystem services that bats provide as well as increasing local knowledge of these factors is key to preventing risky bat interaction behaviors and indiscriminate extermination of local bat populations.
The emergence of new zoonotic diseases is particularly worrisome to governments, leaders and world societies given that they carry multidimensional impacts to economic growth, food security, livelihoods and public health, as well as to social order, international trade and travel, and tourism revenue. The complex, interdependent world we live in today has simply multiplied and deepened the challenges posed by emerging infectious diseases; it has not created them. For its part, FAO is currently working to better understand the drivers of disease emergence and examining the options for comprehensive disease control and management, while at the same time, identifying important conservation issues that need to be taken into account when balancing the needs of people, livestock and wildlife.
Read an article on "Bushmeat consumption, wildlife trade and global public health risks"