PPHSN Advice on Highly Pathogenic Avian Influenza (HPAI) in Southeast Asia from the animal health perspective
The web link below gives a very comprehensive overview of the avian influenza situation in Southeast Asia, mainly from a veterinary perspective given by FAO
Specific information on the Pacific region
1. Importation of poultry, poultry products and other avian species
For at least the duration of the current avian influenza outbreak, Pacific Island countries and territories (PICTs) should not import poultry or poultry products from infected countries, including meat, eggs (for consumption or hatching), feathers, poultry manure, and live birds. The ban should also include any ornamental live birds. This ban is to prevent infection of local poultry and wild birds. The rare occurrence of human infection has always been associated with close contact with infected poultry and has never been shown to be caused by the consumption of poultry products.
2. Migratory birds in the Pacific region
There is a very real possibility that migratory birds could introduce HPAI into the Pacific region. Thankfully however, the birds passing through or originating from Asia are presently overwintering in the South Pacific and won’t return north until around March. Should affected countries fail to control their outbreaks of HPAI by October, there will be a danger of infection from the southerly migration.
3. Highly Pathogenic Avian Influenza (Bird Flu)
HPAI is a poultry disease; occurrences of human infection are extremely rare and only under certain circumstances. The structure of the poultry industry in the Pacific is such that there are very few places where the density of farmed poultry could lead to conditions resembling Southeast Asia. Should an outbreak of the disease occur on a Pacific Island, it would happen within the chicken population, and first indications might be a large number of dead chickens with no evident clinical signs prior to death (see FAO webpages for further details of the clinical disease).
4. Surveillance and monitoring
For most PICTs, passive surveillance of the poultry industry is more appropriate than active surveillance, which can be difficult to carry out and the results may be equally difficult to interpret. HPAI is exactly as its name suggests “highly pathogenic” and will typically cause 50-100% mortality in a chicken shed; it would therefore be hard to miss although in the very early stages; clinical signs in individual birds may not be pathonomonic. It would, however, be much more difficult to spot the presence of the disease in a freerange village system.
5. Investigation of suspicious poultry deaths
Suspicious poultry deaths should be investigated and, if no reasonable cause is found, a laboratory investigation should be carried out. The reference laboratory for HPAI in the Pacific region is the Australian Animal Health Laboratory (AAHL) in Geelong, Victoria, Australia (all details on OIE web site). Any such investigation should be well planned and coordinated, requiring import permits and an IATA-compliant transport system. Any SPC member country requiring assistance with such an investigation should contact the SPC’s Regional Animal Health Service (contact details below).
6. Poultry Vaccination
All Pacific Island countries and territories are currently free from highly pathogenic avian influenza without vaccination. This is the most desirable status to have, as vaccination alone cannot fully protect a country’s poultry population. In many countries the vaccine is banned or discouraged as it can interfere with efforts to eradicate the disease through a stamping-out policy. However, vaccination can be an effective tool for the control of HPAI under certain circumstances. All current OIE-approved vaccines for HPAI are killed vaccines, usually with an oil adjuvant, which must be applied individually to birds. There are reports though of vaccines that have been developed based on recombinant fowl pox virus and DNA expressing the haemagglutinin antigen. The approved vaccines take some time to confer immunity in vaccinated birds and may not fully prevent birds from becoming infected or excreting virus although vaccinated birds rarely become sick. The vaccines are more suitable for use with chicken parent stock and layers, and less so for broilers as their life cycle tends to be very short.
If individual countries have any specific questions or comments, please feel free to join in the dialogue and I will try to update the information as required.
Dr Stephen D. Angus
Secretariat of the Pacific Community
email: [email protected]