Migratory birds do not cause bird flu: experts
By SYED JAFAR ASKARI November 17, 2008 KARACHI - Migratory birds cannot be declared responsible for the outbreak of bird flue in any part of the world, including Pakistan, as recent foreign scientific studies revealed that there is no solid evidence which show correlation between migratory birds and bird flue in any part of the world.
The FAO collected samples from 300,000 to 350,000 wild birds across the world. None of these were found H5N1 positive. After a comprehensive critical review of recent scientific literature it has been concluded that poultry trade, rather bird migration, is the main mechanism of global dispersal of the virus. Talking to The Nation, wildlife expert and Coordinator Natural Resources Management Rabnawaz on Sunday said that such migratory birds (more than 150 bird species) come from Russia and Africa during November and December, and return in February and March.
“After the last outbreak of the H5N1 strain of Avian Influenza and the subsequent allegations that migratory birds are responsible for the spread of the disease to local poultry farms, WWF Pakistan showed its concerns that such statements could have serious repercussions against wild birds population and their habitats. Such statements may prompt mass culling of wild birds and seriously endanger the efforts of conservation organisations and relevant government departments. Since the last outbreak in Sindh, WWF Pakistan has been in close contact with Bird Life International, the world’s authority on birds, which has already carried out significant research and literature review on the role of wild birds, including migratory species in the spread of HPAI H5N1.”
“I would like to highlight some of the scientific facts that though there is some evidence to back the case that migratory wild-birds can spread the H5N1 virus, they are not the main source of the virus spread. Sampling of 5,000 water birds after the outbreak in Nigeria during 2006 found no traces of the virus (AIWEB website). Mapping of the outbreaks across the world have shown that they follow trade routes of poultry rather than migratory flyway of wild birds. After a critical review of recent scientific literature it has been concluded that poultry trade, rather than bird migration, is the main mechanism of global dispersal of the virus,” he added.
Rabnawaz said that the widespread illegal trade of cage birds had transported H5N1 infected birds over large distances. The most likely source of infection in cage birds is at animal ‘wet’ markets in Asia, where domestic and wild-caught birds were kept in close proximity, posing a high-risk of cross-contamination. There was a healthy bird trade in the cities of Pakistan and yet there had been no study to determine whether this was a factor in the spread of the disease or not. “Avian influenza viruses are readily transmitted from farm to farm by the movement of live birds, people (especially when shoes and other clothing are contaminated), and contaminated vehicles, equipment, feed, and cages. Highly pathogenic viruses can survive for long periods in the environment, especially when temperatures are low. For example, the highly pathogenic H5N1 virus can survive in bird faeces for at least 35 days at low temperature (4C). At a much higher temperature (37C), H5N1 viruses survive, while in faecal samples it survive for six days (WHO).”
Media should play a responsible role in the dissemination of information based on facts and scientific research, especially pertaining to the role of wild migratory birds in spreading the H5N1 disease. The disease spreads through the faces, tears, nasal and buccal saliva of or droppings of sick birds or chicken and their contaminated features, he urged. It is pertinent to mention here that the risk of the spread of bird flu, which is a highly contagious viral disease, has been over estimated in the metropolis especially by the media.