Credit Dr. Ian MacKay Virology Down Under
# 7209
H7N9 is genetically a `bird flu’, but one of the ongoing mysteries in the H7N9 outbreak in China is how – with more than 125 people infected - only 46 positive virus samples have been detected out of nearly 70,000 tests conducted on poultry and their environment.
Thus far, the virus has not been detected on farms or commercial poultry operations, only in a handful of samples taken from live bird markets.
Today, the OIE – which has been in meetings with China’s Ministry of Agriculture – released a press release on the H7N9 outbreak and the role they suspect that live-market birds may play in its spread.
Utilizing phrases like `the team made the hypothesis’, `The experts believe’ and `live bird markets may play a key role’ – it is pretty obvious that major gaps remain in our understanding of how this virus is spreading and infecting humans.
The available data remains sparse and incomplete, and a lot of it – frankly – still doesn’t fit together particularly well. All of which helps explain the lack of certainty.
This from the OIE newsroom.
OIE expert mission finds live bird markets play a key role in poultry and human infections with influenza A(H7N9)
Paris, 30 April 2013 – The Ministry of Agriculture of the People’s Republic of China asked the Director General of the World Organisation for Animal Health (OIE) to send OIE experts to assess the situation with influenza A(H7N9) in animals and provide advice.
The mission took place in the spirit of the Tripartite framework between the OIE, the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) of the United Nations. The WHO was leading a mission the week before in collaboration with the Chinese Ministry of Health, while FAO is represented in the country by its local officer, a veterinary doctor who provided support.
The OIE appreciated the availability and transparency of the Chinese authorities in sharing important information, acknowledged the rapid and considerable response made by the Veterinary services to investigate the animal source of human infections, and recognised their efforts to keep the international community informed about the disease situation, including official notifications to the OIE World Animal Health Information System (WAHIS).
According to the information and data collected, the mission confirms that many of the human cases of H7N9 appear to have a link with live bird markets. To date no human cases or animal infections of H7N9 have been detected on poultry farms. During the mission the team made the hypothesis that people could be infected through exposure to infected birds in markets or to a contaminated environment such as live poultry markets where virus is present.
The experts believe that live bird markets may play a key role in human and animal infections with H7N9 and that, even if the overall level of infection is relatively low (having not been detected yet in poultry farms), live bird markets provide an environment for amplification and maintenance of the H7N9 virus. Collaboration between human health and animal health sectors is useful to better understand transmission to humans.
The mission also confirms that currently infection with H7N9 does not cause visible disease in poultry therefore Veterinary Services must be especially involved in preventing its further spread in poultry, particularly through the supervision of the implementation of biosecurity measures on farms.
“Compared with H5N1, at this moment in time H7N9 is not pathogenic to poultry so there are no visible signs of infection, which makes surveillance, prevention and control of the virus in poultry a great challenge”, Dr Keith Hamilton, member of the OIE team, explained.
Because H7N9 infection is unlikely to show visible signs of disease in poultry, the use of reliable and accurate laboratory tests, complying with OIE Standards and guidance from OFFLU, will underpin surveillance and control of the H7N9 virus in poultry. OFFLU is the FAO/OIE global network of scientific expertise on animal influenza.
An extensive surveillance programme in animals is essential to establish the full extent and distribution of the H7N9 virus in the whole country. Effective surveillance will require cooperation between poultry owners and distributors and government Veterinary Services. Veterinary Services including laboratories will need appropriate resources for that purpose.
OIE Reference laboratories for avian influenza, including Harbin Veterinary Research Institute, other laboratories in China, as well as scientists of OFFLU are conducting research on H7N9 to better understand the characteristics of this virus and to ensure that more appropriate diagnostic testing protocols are publicly available.
Recommendations
In case of outbreaks, destruction of infected poultry by Veterinary Services as well as poultry that have been in contact with infected birds is recommended. Culling of at risk-animals must be done following requirements for acceptable killing methods as described in the OIE Code.
There is no evidence to suggest that the consumption of poultry or eggs fit for human consumption could transmit the AI virus to humans. It is safe to eat properly prepared and cooked meat and eggs. Specific precautions when plucking poultry are recommended.
More assessment is needed to swiftly know whether poultry vaccination could be considered as an efficient control option for H7N9. It will be also important to verify whether the H7N9 virus is transmissible from humans to animals because if established, it could be a potential channel for the global spread of the virus.
Trade
Preventing the national and international spread of the H7N9 virus must be a priority.
The strict application by local and national veterinary authorities of Member Countries of OIE science-based standards published in the OIE Terrestrial Animal Health Code (volume 2; chapter 10.4) can prevent spread of the virus from infected poultry. These standards apply to international trade in live poultry, poultry meat, eggs and even feathers.
The application of these international standards also prevents imposition of unjustified trade barriers by importing countries. Controlling illegal trade must also be a priority.
For more from the OIE on this H7N9 virus, you may wish to visit their FAQ.
