Despite news reports suggesting that the World Health Organization may consider raising the alert status for a possible bird flu pandemic, there is no evidence that the virus has become easily transmissible between people, says BMO Nesbitt Burns chief economist Sherry Cooper in a briefing note.

Cooper notes that a family in North Sumatra, Indonesia, has reportedly seen six family members die, and epidemiologists are assessing the degree to which human-to-human transmission played a role. There have been no sick birds found in the vicinity as yet, she says. “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,” Cooper says.

“The reassuring news is that there is no evidence that the virus has mutated to become more efficiently transmissible between people,” Cooper adds. “Also, many others were exposed to this family weeks ago and have shown no evidence of virus. To date, the investigation has found no evidence of spread within the general community and no evidence that efficient human-to-human transmission has occurred.”

“While the media are certainly all over this story, and some of the community of experts supports a move by the World Health Organization to a higher alert status, it is improbable that WHO will take action based on the evidence uncovered to date,” Cooper says. “Some are speculating that this particular family might be genetically predisposed to the H5N1 virus, while it is still very difficult for the general population to contract the disease.”

The WHO has assessed that “the world is presently in phase 3: a new influenza virus subtype is causing disease in humans, but is not yet spreading efficiently and sustainably among humans”, Cooper says. A move to a phase 4 alert would require evidence of increased human-to-human transmission from a new, more efficiently transmitted virus, it adds. “Given that no new virus has been found, the WHO will likely continue with the phase 3 alert, but things could change quickly.”