The Joint FAO-IAEA Division is supporting Member States to combat H7N9 avian influenza - a new avian influenza virus concern for Humans
Avian Influenza, also known as “Avian Flu” or “Bird Flu” is caused by a virus that has a reservoir in wild birds. Usually, wild birds are resistant to the disease but do carry and secrete the virus, transmitting it to domesticated birds (chicken, duck, and turkey) that are susceptible and can become sick and die. The influenza A virus is found in the saliva, nasal secretions, and faeces of the birds. There are several subtypes of influenza A virus, based on differences in two proteins on the virus membrane: hemagglutinin (HA) and neuraminidase (NA). There are 17 known HA subtypes (H1 to H17) and 9 NA subtypes (N1 to N9) and therefore, there are many possible combinations of HA and NA. Some of the strains are of the “low pathogenic” form causing mild, if any, clinical signs in poultry and others are “highly pathogenic” causing high morbidity and mortality, e.g. the H5N1 that killed millions of birds and forced the culling of several hundreds of millions more in recent years, especially in Asian regions.
Since March 31, 2013, an H7N9 avian influenza A virus has been detected in four provinces of eastern China and has infected 640 people of which 250 have died, some 1000 contacts are under medical observation (situation as of 24 March 2015). Importantly, this is the first time that this subtype has been found in humans. The virus is classified as low pathogenic (i.e. infected birds look healthy even though they carry the H7N9 virus and therefore are a potential threat to human health). It is a new subtype found in human and it derives from the combination of genes from 3 different avian influenza viruses. While there is clear indication of the transmission of the H7N9 virus from poultry to humans, there has been no indication of human to human transmission and therefore, at present, the risk to public health seems to be low. No cases of this new H7N9 subtype have been reported outside China.
The Chinese Center for Disease Control and Prevention has published genetic sequences of H7N9 identified in humans confirming that it is derived from avian influenza viruses. Preliminary data indicates that the H7N9 avian virus has mutated in poultry over time allowing it to adapt and grow at the normal body temperature of mammals.
Since the H7N9 avian influenza virus is sub-clinical in poultry (i.e. infected or carrier birds look healthy and normal but pose a risk to in-contact humans), the Joint FAO-IAEA Division’s Animal Production and Health Laboratory (APHL) is investigating the use and adaptability of early and rapid molecular diagnostic technologies to identify poultry that are infected or that carry the H7N9 virus. The diagnostic primers and probes available to amplify both the Matrix and H7 genes of the Chinese H7N9 by real-time PCR are based on published sequences, but it is still important to determine whether these reagents will detect all variable gene sequences circulating in poultry. The Animal Production and Health Laboratory at Seibersdorf is ready to support Member States on this problem in several ways:
- Provide surveillance and sampling guidance and advice
- Provide real-time PCR standard operating procedures (SOPs) for the early and rapid diagnosis of the H7N9 avian influenza subtype in poultry, and associated capacity building and training
- Provide technical and expert services (advice, guidance, protocols, guidelines)
- Provision of reagents (primers and probes) and procedural guidelines
- Technical and expert on-site assistance and services
- Updated information on H7N9 situation
Related Story in the IAEA
Important H7N9 Avian Influenza links:
- Q&A: http://www.fao.org/news/story/en/item/173704/icode/
- FAO press release: http://www.fao.org/news/story/en/item/173655/icode/
- WHO FAQ on H7N9 virus: http://www.who.int/influenza/human_animal_interface/faq_H7N9/en/
- Centers for Disease Control and Prevention: http://www.cdc.gov/flu/
- World Organisation for Animal Health (OIE): http://www.oie.int