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| Ducks may be behind unexpected HPAI outbreaks | |
7 June 2007, Hanoi – HPAI outbreaks currently occurring at this unexpected time of the year are due to recent increased numbers of grazing ducks directly associated with the rice harvest – many of which did not receive H5 vaccine, says the Food and Agriculture Organization of the United Nations (FAO). This is one of the key findings of a recently conducted a joint field investigation in Nam Dinh province with Vietnamese authorities in areas where outbreaks of H5N1Highly Pathogenic Avian Influenza (HPAI) have been reported. Historically the period leading up to the Lunar New Year (Tet) in January/February has been recognized as the highest risk period for spread of H5N1- due to the high consumer demand being met by an increase in poultry production, and also associated with ‘winter' in the north – cold temperatures favouring survival of the virus in the environment. Local authorities stated that ducks are often hatched in nearby provinces and moved to Nam Dinh province to graze on paddies after the rice harvest. “Free range duck production is an excellent system for farming, but there are risks and challenges involved,” said Mr Andrew Speedy, FAO Representative in Viet Nam . FAO supports the decision to end the ban against hatching of waterfowl which took effect from March 2007, but recommends that all ducks are vaccinated and that measures be taken to ensure that all hatcheries meet basic bio-security standards, and that ad hoc small hatcheries are discouraged. In the case of Nam Dinh province the investigation team noted that the turnout of young ducks onto the paddies was after the earlier vaccine campaign (itself appearing effective as few chicken farms have been affected), and their breeding cycle may not have coincided with campaigns in the provinces of origin – hence their unvaccinated status. In this current (fifth) wave of outbreak which began in May 2007, more than 35 outbreaks have been reported in 15 provinces, mostly in the Red River Delta. Additionally the Ministry of Health has confirmed two human cases which await further reconfirmation from reference laboratories of the World Health Organization (WHO). “We are saddened by the two human cases of H5N1 but these were both in persons working closely with poultry. It further demonstrates the need for education and awareness, and for care and attention in managing and working with chickens and ducks” added Mr Speedy. Viet Nam was first affected by the H5N1 avian influenza outbreak in 2004 and in the first three waves of the disease outbreaks in 2004-2005, 93 human cases were reported of which 42 were fatal, and 51 million poultry were culled. There was an interval of 12 months where no poultry outbreak from H5N1 was reported throughout the country, until the outbreaks were confirmed in December 2006. In the fourth wave, 45,000 poultry were culled and sporadic outbreaks were reported from February to March 2007. Current vaccines are still considered effective. FAO is assisting the Government to study the virus circulating in poultry and monitor the effectiveness of the vaccines with ongoing laboratory trials. “So far genetic sequencing of recent virus isolates have shown no significant change in the antigenicity of the virus”, said Dr Jeffrey Gilbert, Chief Technical Advisor of FAO's AI Programme in Viet Nam Dr Gilbert emphasized that the National Vaccination Campaign, which is being implemented in 63 provinces, has to be implemented alongside other systems in place that support effective detection, disease outbreak investigations and support early response. In the medium to long term, he said it is crucial to improve further the capacity of veterinary services including effective animal disease surveillance system, laboratory diagnostic capacity and the quarantine system. Additionally, improved animal husbandry practices at farms, improved hygiene at markets and slaughter points should be put into practice to prevent spread of disease and possible human infection. For further information, please contact:
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