Indian Veterinary Research Institute, Izatnagar-243122, Uttar Pradesh.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Avian influenza, commonly known as bird flu, is caused by type A influenza viruses. The symptoms can vary from a mild disease, called as Low Pathogenic Avian Influenza (LPAI) with little or no mortality to a highly fatal, rapidly spreading epidemic called as Highly Pathogenic Avian Influenza (HPAI) depending on the infecting virus strain, host factors, environmental stressors and disease management practices. Recent epizootics of highly contagious, OIE list A disease, Avian Influenza caused by H5N1 strain of the Avian influenza virus in the Asian continent, has jumped the species barrier, causing severe disease with casualties in humans and poultry alike. This has led to the implementation of stamping out policies resulting in the depopulation of millions of birds in the affected areas.
Outbreaks of H5N1 highly pathogenic Avian influenza (HPA1) have been reported from various countries in Asia. Since December 2004, outbreaks of HPA1 H5N1 in poultry have been reported in Cambodia, Thailand Vietnam and cases affecting humans have been reported in Cambodia. In January 2005, AI virus subtype H5N1 was reported in herons in Hong Kong special Administrative Region of China. But, in November 2004, outbreaks of HPAI subtype H7 were reported in unvaccinated chickens in Pakistan. Sporadic reports of disease caused by H5NI emerged from far-flung areas in the continent as Siberia and in diverse species of birds including flamingoes and migratory geese. Though the virus has not yet accumulated genetic mutations to facilitate direct human-to-human transmission, the threat of a human pandemic is still very much on. In the short term, it is important to manage the risks to human health and prevent spread of the viruses. Improved biosecurity, stamping out of known infection, vaccination and implementation of basic public health measures only can ensure this. The need for vigilance to find new cases and rapid isolation of infected or suspected flocks from susceptible poultry and humans are high priorities. HPAI viruses are still circulating in a number of Asian countries. Most of the affected countries face challenges in terms of surveillance capacity, which can lead to cases of infection or disease remaining undiagnosed. Two of the affected countries are using vaccination to control HPAI as response to endemic disease and infection in poultry flocks. This appears to have reduced the levels of disease, virus shedding and potential for further spread.
