The livestock revolution in developing countries has been associated with the growth of unprecedented concentration of animals in the urban and peri-urban areas of developing, with major implications for human and animal health, according to the bank's World Development Report-2008.

It said that out of 1,415 species of infectious organisms known to be pathogenic to humans, 61% were zoonotic or transmissible from animals to humans. Out of the 175pathogenic species of infectious organisms considered to be "emerging" (or re-emerging) in humans, 75% were zoonotic. The poor were specially exposed because of the proximity of their living spaces to farm animals, it said.

Zoonotic diseases of significance in developing countries fall into three categories based on the form of transmission – foodborne (cysticercosis, brucellosis, tuberculosis), infectious (avian flu, tuberculosis) and vector-borne (rabies or trypanosomosis).

Animal disease has long been a major economic issue. The losses from animal deaths from H5N1 strain of highly pathogenic avian flu and the costs of controlling it run into the tens of billions of dollars, according to the World Bank.

Since late 2003 the H5N1 strain of avian flu has been responsible for 4,544 documented outbreaks in poultry in 36 countries, including India, associated with 269 human cases and 163 fatalities, as of January 2007. The virus is not easily transmitted to and within humans. But the great concern is that it could mutate within either animal or human hosts to become easily transmissible from humans to humans, raising the possibility of a disastrous pandemic.

According to the World Bank as vaccination were expensive and difficult for implementation under developing country conditions, controlling zoonotic diseases in animals vector becomes critical. The primary method of controlling animal diseases is to quickly cull diseased animals and others may have come in contact with, thus reducing the viral load.