No easy human-to-human transmission of bird flu yet found – UN health agency

Although human contagion cannot be ruled out in a family cluster of bird flu cases in Indonesia, the United Nations health agency has so far found no evidence that “efficient” human-to-human transmission has occurred, a development that would signal a potentially dangerous mutation of the virus into a deadly pandemic.

But the UN World Health Organization (WHO) and the Indonesia Health Ministry are concerned about the situation in Kubu Sembelang in North Sumatra and have intensified investigation and response activities there.

Priority is now being given to the search for additional cases of the illness in other family members, close contacts, and the general community after seven members of an extended family became infected with the H5N1 virus, six of them fatally, WHO said in its latest update.

All confirmed cases in the cluster can be directly linked to close and prolonged exposure to a patient during a phase of severe illness. Although human-to-human transmission cannot be ruled out, the search for a possible alternative source of exposure is continuing.

Although more than 200 million birds have died worldwide from either the virus or preventive culling, there have so far been only 218 human cases, 124 of them fatal, since the current outbreak started in South East Asia in December 2003, and these have been ascribed to contact with infected birds.

But experts fear the virus could mutate, gaining the ability to pass from person to person and, in a worst case scenario, unleashing a deadly human pandemic. The so-called Spanish flu pandemic that broke out in 1918 is estimated to have killed from 20 million to 40 million people worldwide by the time it had run its course two years later.

In a related development, some 300 scientists from over 100 nations will gather in Rome next week for a two-day meeting to try and shed light on one of the most controversial aspects of the H5N1: how far wild birds are to blame for spreading the virus.

The 30-31 May conference organized by the UN Food and Agriculture Organization (FAO) and the inter-governmental World Organization for Animal Health (OIE), will seek to determine just what role wild birds, as opposed to domestic poultry, play in propagating the disease.

The main problem, according to FAO Chief Veterinary Officer Joseph Domenech, is that no one knows for sure whether wild birds can act as long-term reservoirs of such viruses.

“Where they are not reservoirs but only victims of contamination from poultry, then prevention has to remain at the domestic bird level,” he said. “But where they are, we have to find out which birds are involved and where they migrate to in order to prevent other wild birds and poultry being infected.”

While it has been demonstrated that migrating birds can carry the virus over long distances - in Siberia, Eastern and Western Europe for example - it is not clear where the infection originated, although most scientists point the finger at domestic fowl.

In the early spring, it was feared that there would be large-scale outbreaks in Africa. And though bird flu did hit six African countries, this was less than expected and there was no evidence to link the outbreaks with wild birds. Similarly, widespread new cases were feared in Europe but largely failed to materialize.

“Lots of questions remain without answers,” Mr. Domenech said. “We therefore need to increase research and surveillance to better understand the epidemiology of the disease.”