The United Nations health agency today voiced concern over the expanding geographical range of bird flu, which officials fear could in a worst-case scenario mutate into a deadly human pandemic, and it called for heightened surveillance and the rapid introduction of containment measures.
“The possible spread of H5N1 avian influenza to poultry in additional countries cannot be ruled out,” The World Health Organization (WHO) said in its latest update on the virus, which has now been reported in Russia and Kazakhstan after being confined to South-East Asia.
“The expanding geographical presence of the virus is of concern as it creates further opportunities for human exposure. Each additional human case increases opportunities for the virus to improve its transmissibility, through either adaptive mutation or reassortment. The emergence of an H5N1 strain that is readily transmitted among humans would mark the start of a pandemic,” WHO added.
The agency has repeatedly stressed the need for scientists to determine possible changes in the behaviour of H5N1 to assess the risk of a human pandemic. The so-called Spanish flu pandemic of 1918-1920, unrelated to the present virus, is estimated to have killed between 20 million and 40 million people worldwide.
Overall, there have been more than 100 reported human infections, about 50 of them fatal, since the first case linked to widespread poultry outbreaks in Viet Nam and Thailand was reported in January last year. Nearly 140 million domestic birds have died or been culled over the past year in South-East Asia in an effort to curb the spread of the disease.
No human infections have been reported in the latest outbreak among birds in Russia and Kazakhstan.
WHO recommended heightened surveillance for outbreaks in poultry and die-offs in migratory birds, and rapid introduction of containment measures, and heightened vigilance for cases of respiratory disease in persons with a history of exposure to infected poultry in countries with known poultry outbreaks.
The provision of clinical specimens and viruses from humans and animals to WHO reference laboratories and those run by the UN Food and Agriculture Organization (FAO) and the intergovernmental World Organization for Animal Health (OIE), allows studies that contribute to the assessment of pandemic risk and helps ensure that work towards vaccine development stays on course, the update noted.