MEMBERS OF an Indon-esian family who died of bird flu may have infected each other and health experts are tracing anyone who had contact with them, the head of the U.S. Centers for Disease Control and Prevention said yesterday.
The seven deaths in the family in Kubu Sembilang village in north Sumatra over the past few weeks is the largest family cluster of bird flu victims known to date. But villagers are now cooperating with health investigators and there is no sign that the H5N1 avian flu virus has infected anyone outside the family, said CDC Director Dr. Julie Gerberding.
Nonetheless, financial markets were jittery and buyers drove up stocks in companies working on influenza vaccines and drugs in what one analyst called a 'knee-jerk reaction'.
World Health Organisation and Indon-esian health officials cannot find the source of the infection in Sumatra, but Gerberding said genetic sequencing shows the H5N1 virus has not mutated substantially.
"The concern that has been raised ... is the potential for evidence for human-to-human transmission in this outbreak," Gerberding told reporters in a telephone briefing.
"This is the leading hypothesis that is under investigation. The likely source was poultry exposure, as we have seen time and time again."
But the case may represent what is known as tertiary transmission -
someone may have been infected by a chicken and infected a relative, who in turn infected someone else.
While rare cases of human-to-human transmission have been seen before - in Thailand and Vietnam - doctors believe that one person only infected one other in those instances and the chain of transmission stopped there.
"A person to person-to-person transmission chain is very important ... that is why there has been such attention and such an effort," said Gerberding.
Firdosi Mehta, acting representative of the WHO in Indonesia, said experts in Kubu Sembilang were acting to contain any further spread.
Financial markets were spooked by fears that the Indonesia cluster could be the start of a pandemic.
Currencies in Asia fell. Shares in poultry industry companies like Tyson Foods, Pilgrim's Pride and Gold Kist and Sanderson Farms Inc. all declined and there was concern at the corn and soybean pits of the Chicago Board of Trade, the largest grain exchange.
Bird flu has infected 218 people in 10 countries and has killed 124 since it re-emerged in Asia in 2003. It mostly infects birds, but if it changes into a form that easily passes from person to person it could touch off a deadly pandemic.