Times OF India/New Delhi/03/02/08
Infections transmitted from animals to humans are a source of worry across the globe
Saira Kurup | TNN
Unsure about whether you should gorge on that butter chicken? Bird flu isn’t the only thing you need to worry about. Diseases spread by birds, pigs, mosquitoes, cattle and other animals — wild and domesticated — are a growing problem, affecting millions of people every year. In recent times, the emergence of new diseases like Severe Acute
Respiratory Syndrome (SARS), Mad Cow disease and bird flu have raised awareness about the danger of infections naturally transmitted between animals and man, known as zoonoses.
Some dreaded zoonotic diseases like rabies and plague have been feared for quite a while, but a new worrying factor is such illnesses are no longer just national problems. If there’s bird flu in China, India needs to worry — thanks to global movement of people, animals and microbes. For, as a senior National Institute of Communicable Diseases
(NICD) official puts it, “The world has become a village.”
In addition, human activities are changing climate and environment, disturbing ecological equilibrium and creating conditions conducive for the emergence or reemergence of microbes. An NICD-WHO report, “Zoonotic diseases: Public health importance” says such activities include deforestation, incursion into virgin territories, industrialization, urbanization, changing farming practices, increasing trade in animal products and rising density of animal population.
The report says there are more than 300 zoonotic diseases of diverse origins.
Worldwide studies show that about 75% of emerging human infectious diseases are of zoonotic origin. The culprits involved are varied — virus, protozoa, rickettsia (a kind of bacteria) and fungi; fleas and mosquitoes which act as transmission agents etc. The origin of the modern-day scourge, AIDS, is still disputed, but one theory is that it originated from simians, possibly chimps in Africa. Bird flu, monkeypox, Nipah virus, SARS (civet cats suspected) and Ebola virus (simians) are known to be zoonotic, a result, to a greater or lesser extent, of interactions with animals. The senior official says, “In addition, India has a large rural population and a large domestic, wild and semi-wild animal population, with close interactions between the two.” Cattle, sheep, pigs and poultry live in close proximity to people in villages and farms. People in urban areas are also not safe because of largescale movement of migrants from rural areas.
Pets are also a risk factor. Says Delhi veterinarian Gautam Unny, “Rabies, leptospirosis (a contagious, bacterial disease carried by rodents, wildlife and domestic animals) and skin diseases like scabies can be acquired from pets.” Toxoplasmosis is a common parasitic infection passed on by cats.
At times, natural disasters can also precipitate an epidemic. For example, leptospirosis, considered the most widespread of zoonotic infections in the world, broke out in Mumbai following the 2005 floods.

Similarly, in 1994, India saw an outbreak of human plague. Studies traced its origins to the earthquake in Latur the same year. Says the senior NICD official, “The quake brought together wild and domestic rodents. The people who took refuge in temporary shelters came in contact with these rodents.” Some other important zoonoses are anthrax (from herbivores), brucellosis (from goats, sheep, cattle), bovine TB and Japanese encephalitis or brain fever, as it’s more commonly known. Brain fever, a viral disease transmitted from pigs to humans (mostly children) via mosquitoes, is specially endemic in Uttar
Pradesh in 2005, of the 6,550 (with 1,645 deaths) cases reported in India, 5,978 were from the state.
However, we still don’t have all the answers. We are continuing to interfere with nature and have no idea about the kind of diseases that will emerge in future.