By Caitlin Aylward
Some 60 percent of all human diseases, and 75 percent of all emerging infectious diseases, are zoonotic (human-animal transmitted infectious diseases). In light of these staggering figures, the Nairobi-based International Livestock Research Institute (ILRI), recently released a report mapping the top 20 geographical hotspots of emerging zoonotic diseases and emerging disease outbreaks. Among the study’s findings, the report reveals the heavy disease burden of zoonoses for one billion of the world’s poor livestock holders, in addition to surprising new data on emerging diseases in industrialized countries, many of which have never been mapped.
The study identifies three classifications of high-priority zoonoses, the first of which, endemic zoonoses, causes the vast majority of illness and death in poor countries. Endemic zoonoses, such as brucellosis, are present in many places and are usually transmitted as food-borne illnesses. Given its widespread nature, the review suggests that endemic zoonoses are of greatest concern where the objective is reducing the burden of human illness and enhancing the profitability of livestock for poor small-scale livestock farmers in the developing world.
Other zoonotic diseases include epidemic zoonoses, such as anthrax and Rift Valley fever, which typically occur as outbreaks and are sporadic in temporal and geographical distribution.
And the report examines emerging zoonoses, which are relatively rare and are characterized by rapidly increasing rates of incidence or expanding geographic ranges. Emerging zoonoses, such as bird flu and HIV-AIDS, can spread to cause global cataclysms. While zoonotic diseases can be transmitted to humans by any animal, most human infections are transmitted from the world’s 24 billion livestock.