Thirteen countries have now reported the occurrence of bird flu in wild and domestic birds since the beginning of the month, part of a recent pattern of rapid geographical spread of the virus, which in a worst case scenario could develop into a lethal human pandemic, the United Nations health agency said today.
But apart from Iraq, none of the countries newly affected during February has reported human cases of the H5N1 virus, the World Health Organization (WHO) said. Iraq has reported two human cases, both of which were fatal; samples from several other patients are currently undergoing tests.
The 13 countries, listed in order of reporting, are Iraq, Nigeria, Azerbaijan, Bulgaria, Greece, Italy, Slovenia, Iran, Austria, Germany, Egypt, India and France. Malaysia yesterday reported a fresh outbreak in poultry after having been considered free of the disease for more than a year.
Since the first reports of H5N1 in Asia at the end of 2003, 170 human cases have been reported, 92 of them fatal, mostly in South-East Asia and China. Nearly 200 million domestic poultry have died or been culled in order to contain the spread. The economic loss to the affected Asian countries has been estimated at around $10 billion.
UN health officials have warned that the virus could evolve into a lethal human pandemic if it mutates into a form which could transmit easily between people. Cases so far have been traced to infection directly from diseased birds. The so-called Spanish flu pandemic of 1918-1920 is estimated to have killed from 20 million to 40 million people worldwide.
The situation in the 13 recently affected countries varies greatly. Most European countries with good veterinary surveillance have detected the virus in a small number of wild birds only, with no evidence to date of spread to domestic birds.
In Azerbaijan, detection has coincided with die-offs of domestic birds. In Egypt, outbreaks in domestic poultry have now been confirmed in 10 governorates; deaths have also been reported in exotic zoo birds. In Iraq, presence of the virus in birds was found only after the country confirmed its first human case.
In Nigeria, as in India, the first cases were detected in large commercial farms, where the disease is highly visible and outbreaks are difficult to miss.
For human health, experience elsewhere over the past two years has shown that the greatest risk of cases arises when the virus becomes established in small backyard flocks, which allow continuing opportunities for close human contact, exposures, and infections to occur.
All available evidence indicates that the virus does not spread easily from poultry to humans. To date, very few cases have been detected in poultry workers, cullers, or veterinarians. Almost all cases have been linked to close contact to diseased household flocks, often during slaughtering, de-feathering, butchering, and preparation of poultry for consumption.
No cases have been linked to the consumption of properly cooked poultry meat or eggs, even in households where disease was known to be present in flocks.