In South Asia, one of the world's most densely populated regions, deadly diseases from animals, like the nipah virus, brucellosis, anthrax and even avian flu, cross international boundaries with ease.
A fruit bat on the India-Bangladesh border could spread the deadly nipah virus when it licks the juice of the date palm tree being collected by farmers. Likewise, cattle grazing in grasslands spanning borders could carry with them spores of the anthrax disease, or the ticks on them could spread brucellosis. According to experts, zoonotic diseases, transmitted from animals to humans, are able to cross international borders in South Asia due to the porous borders, poor awareness and surveillance mechanisms coupled with high density of population.
Among the diseases spread by animals in South Asia are the plague, scrub typhus, leptospirosis and avian flu. Brucellosis causes abortions in bovines, and sheep and goat. In humans, the fever can be confused with typhoid.
According to a senior public health specialist, Public Health Foundation of India (PHFI), South Asian borders are porous; humans cross over and along with them bring pathogens.These are tropical countries where the human-animal interface is very, very intense.
In South Asia, there is a lot of unorganised backyard animal and poultry farming. Humans and animals come into close contact in these farms. There is poor knowledge of hygienic practices; bio safety standards are not up to the mark; and there is every likelihood of pathogens crossing the borders.
With its poverty, high population, poor safety practices, it makes the South Asia region a hot spot for zoonotic diseases," said a senior public health specialist, Public Health Foundation of India , on the sidelines of a meeting on zoonotic diseases organized by One Health Alliance of South Asia (OHASA) attended by delegates from India, Bangladesh, Nepal and Pakistan.
India saw its first outbreak of nipah virus - which affects the neurological and respiratory system and can cause death - in Siliguri in West Bengal in 2000. The saliva and urine of the fruit bats - which were unwitting hosts to the nipah virus - contaminated the date palm juice collected by farmers, thereby spreading the virus to humans, said Jonathan H. Epstein, a disease ecologist.
The H1N1 or avian flu virus in wild birds finds its way to backyard poultry farms located next to jungles. "Poultry farmers trade the chickens even if they fall sick, and these infect others as well as the humans handling them," Epstein, EcoHealth Alliance's associate vice president and member of OHASA Steering Committee, told.
According to Epstein, the increasing population has led to people moving closer to jungles and intruding into wildlife areas, thereby increasing the chances of catching such infections. Also the growing demand for protein has increased the man-animal interaction.
"Half of the infections afflicting humans come from animals," said the expert, adding that many of the infections are emerging or new ones like the West Nile virus, spread by the mosquito.Japanese encephalitis is transmitted by mosquitoes to humans and affects a large number of people in India every year. However, the actual host to the killer virus are pigs and birds, from which it is transmitted to mosquitoes.
To tackle zoonotic diseases in South Asia, the veterinary and wildlife authorities need to be on board along with health officials.
"We need to synergise collaboration between the veterinary, human and wildlife sectors," says a senior public health specialist, Public Health Foundation of India.
In villages situated next to national parks, many cow grazers take their animals inside the parks to graze, which in turn leads to animals catching the anthrax spores from deer or bison and pass them on to humans.
According to PHFI, besides human encroachment, climate change is another reason for the spread of zoonotic disease as animals migrate to newer areas more conducive to them. The illegal trade in wildlife also helps spread the disease.
"There is need for inter-sectoral coordination, which needs to translate to action. Otherwise we can't be effective in tackling the spread of zoonotic diseases. It needs a lot of collaboration between countries of the South Asia region," maintains PHFI.