Avian influenza –spread of the virus to new countries

21 February 2006

Rapid geographical spread of the virus

The occurrence of the disease in India, reported on 18 February, is part of a recent pattern of rapid geographical spread of the virus in wild and domestic birds. India is one of 13 countries that have reported their first cases of H5N1 infection in birds since the beginning of February. (The 13 countries, listed in order of reporting, are Iraq, Nigeria, Azerbaijan, Bulgaria, Greece, Italy, Slovenia, Iran, Austria, Germany, Egypt, India and France.)

On 20 February, Malaysia reported a fresh outbreak in poultry after having been considered free of the disease for more than a year.

The situation in these 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 of the virus 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.

Apart from Iraq, none of the countries newly affected during February has reported human cases. Iraq has reported two human cases, both of which were fatal; samples from several other patients are currently undergoing tests.

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, defeathering, 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.