Jun 13, 2007 (CIDRAP News) – Vietnamese health officials announced yesterday that two more patients tested positive for H5N1 avian influenza, while animal-health officials suggested that unvaccinated ducks may be to blame for Vietnam's recent rash of poultry outbreaks.
Nguyen Huy Nga, director of Vietnam's preventive medicine administration, said tests at a Vietnamese laboratory confirmed that a 28-year-old man from Tranh Hoa province and a 29-year-old woman from Ha Nam province, both in the northern part of the country, were infected with the H5N1 virus, according to an Associated Press (AP) report yesterday.
Other media reports were unclear on the patients' exact ages and the gender of the patient from Tranh Hoa. However, most reports, including stories today from two Vietnamese news services, said the patient from Tranh Hoa got sick after eating meat from an infected duck and was released from a hospital after recovering from pneumonia-like symptoms.
Vietnamese news services also reported that the woman from Ha Nam province was in critical condition at the Hospital for Tropical Diseases in Hanoi. Officials were trying to learn how she was exposed to the virus.
If the World Health Organization (WHO) confirms the two cases and two others reported by Vietnam over the past few weeks, the country's H5N1 case count will rise to 97. For now, the count stands at 93 cases and 42 deaths.
Since early May, Vietnam has battled H5N1 outbreaks in 15 provinces. The United Nations Food and Agriculture Organization (FAO) and Vietnamese agriculture officials recently conducted a joint investigation of outbreaks in Nam Dinh province, one of the affected areas. In a report released 2 days ago, the FAO said this year's outbreaks are occurring later in the year than expected.
Historically, January and February have been the worst months for the spread of H5N1, because of high consumer demand for poultry products during Lunar New Year (Tet) celebrations and because cooler temperature have been thought to favor the virus's survival in the environment, the FAO report said.
Investigators believe an increase in the numbers of ducks, many of which are unvaccinated, released to graze on newly harvested rice paddies are the reason for the later-than-usual spike in bird outbreaks this year, the report said. Farmers typically bring ducks that are hatched in nearby provinces to graze on harvested paddies in Nam Dinh province. Investigators found that unvaccinated young ducks, whose breeding cycles may not have corresponded with local vaccination campaigns, were released onto the rice paddies.
"Free range duck production is an excellent system for farming, but there are risks and challenges involved," said Andrew Speedy, FAO's Vietnam representative, in the report. The agency recommends that officials ensure that all ducks are vaccinated, require hatcheries to meet basic biosecurity standards, and discourage small hatcheries.
The FAO said current poultry vaccines are still effective and that it was assisting the government with the study of the H5N1 virus circulating in poultry. Jeffrey Gilbert, chief technical advisor of the FAO's avian influenza program in Vietnam, said, "So far, genetic sequencing of recent viral isolates has shown no significant changes in the antigenicity of the virus."
Elsewhere, the health ministry in Malaysia said yesterday that five people in two central states have been quarantined for suspected H5N1 infection, Agence-France Presse (AFP) reported. The patients include three children and two adults. An 11-year-old boy was isolated at a hospital in Selangor state, while the others were hospitalized in Pahang state, the AFP report said.
Chua Soi Lek, a health ministry official, told AFP all the patients had had contact with dead chickens. He added that 16 other people who were hospitalized with flulike symptoms have tested negative for the virus.
The H5N1 virus resurfaced in Malaysian poultry early this month, marking the country's first outbreak since February 2006, but it has never had a confirmed human H5N1 case.
Meanwhile, the WHO yesterday confirmed the latest H5N1 case reported in Egypt, in a 4-year-old girl from Qena governorate who got sick on Jun 7 and was hospitalized 3 days later. She was reported to be in stable condition. An initial investigation revealed the girl had been exposed to dead birds. The case confirmation brings Egypt's H5N1 total to 36 cases, of which 15 have been fatal.
Jun 7 FAO report
Jun 12 WHO statement