Feb 2, 2004 (CIDRAP News) – Two more human deaths resulting from H5N1 avian influenza (bird flu) were reported in Southeast Asia today, while the World Health Organization (WHO) said it was investigating two possible cases of person-to-person spread of the disease in Vietnam.

In addition, China reported outbreaks of the highly pathogenic avian flu in four more provinces around the country, bringing the number of affected provinces to 10, according to the WHO.

A 58-year-old woman in Thailand died of the illness today, the WHO said. Her case brought the number of confirmed cases in Thailand to four, of which three were fatal. An Associated Press (AP) report said the woman died earlier and that her H5N1 infection was confirmed by autopsy.

The AP also said an 18-year-old man died of avian flu in Ho Chi Minh City, Vietnam, today. His case was not yet reported on the WHO Web site at this writing.

The WHO reported 14 confirmed human cases of avian flu as of today, including the four in Thailand and 10 in Vietnam. Eight of the Vietnamese patients died.

The WHO said two members of a family in Thai Binh Province, Vietnam, might have acquired avian flu from other family members. The agency is investigating respiratory illness in a 31-year-old man, his two younger sisters, and his 28-year-old wife.

Both the man and the two sisters died, but the wife fully recovered, the agency said. Test results over the weekend confirmed H5N1 influenza in the sisters, but neither the man nor his wife was tested.

The family gathered in late December for the man"e;s wedding, and the man and one sister reportedly handled ducks while preparing a meal Jan 4, the WHO said. But investigators found no evidence that the man"e;s wife or his other sister had any direct contact with poultry. Both sisters helped care for the man after he became ill and might have been exposed in that way. "Direct human-to-human transmission following this close exposure is thus one possible explanation," the agency said.

However, the WHO has not ruled out contact with an infected bird or some other environmental exposure to the virus as the route of exposure, officials said. They said local authorities have reported no other similar illness cases in family members, wedding guests, other members of the local community, or healthcare workers.

The WHO said limited person-to-person spread of highly pathogenic avian flu "is not entirely unexpected," since it happened in Hong Kong in 1997 and in the Netherlands in 2003.

Disease experts fear that if a person already infected with an ordinary flu virus acquires the avian flu, the two viruses could share genes and give rise to a new strain that could spread easily from person to person. Such an event could trigger a pandemic like those that occurred in 1918, 1957, and 1968, it is feared.

In other developments, Chinese authorities reported new suspected outbreaks of H5N1 influenza in poultry in the eastern province of Zhejiang, the southwest province of Yunnan, the central province of Henan, and in Xingjiang Uygar Autonomous Region in northwestern China, according to the WHO. The Zhejiang outbreak involved geese, while the three others involved chickens.

In addition, the WHO said new outbreaks were reported in two provinces that had previous outbreaks—Hubei (chickens and ducks) and Guangdong (geese). Thus far, H5N1 avian flu has been confirmed only in Guangxi, Hunan, and Hubei, the agency said.