Joint Statement on Avian influenza
RSPB, BirdLife International, WWT and BTO have updated their joint statement on avian influenza (14 October 2005). This explains what it is and indicates the risks and consequences associated with the virus. Government and non-government organisations are discussing these issues and will continue so to do.
The joint statement reads:
The recent spread of avian influenza (bird flu), caused by the highly pathogenic H5N1 strain, across Asia and into Eastern Europe poses challenges to those concerned with the health of domestic poultry and the conservation of wild birds. Within the UK, the main threat is to the poultry industry and actions taken by the UK Government are targeted at minimising this risk, by maximising our vigilance and preparing a contingency plan should the virus arrive. BTO, RSPB and WWT are working with Government departments to assess the risks posed by movements of wild birds, to undertake surveillance and to disseminate guidance for birdwatchers.
There is no evidence that H5N1 infections in humans have been acquired from wild birds. Human infections have occurred in people who have been closely associated with poultry. The risk to human health from wild birds in the UK is extremely low and can be minimised by avoiding contact with sick or dead birds. However, there is a possibility that this virus could develop into one that might be transmitted from human to human. If this happens, then it is most likely to happen in SE Asia, from where it could then spread rapidly around the world.
There are numerous strains (at least 144) of avian influenza, many of which circulate in wild birds at low levels, but which can occur more frequently in waterbirds. Most of these viruses within wild bird populations are benign.
Highly pathogenic-avian influenza viruses (including H5N1) can cause great mortality in domestic poultry flocks but are very rare in wild birds. H5N1 is highly pathogenic but was never recorded in wild birds before the recent outbreaks in SE Asia, Russia and countries around the Black Sea. It is likely that It originated in domestic poultry through mutation of low pathogenic sub-types and was subsequently passed from poultry to wild birds.
Transmission is promoted in domestic flocks due to the density of birds and the consequent close contact with faecal and other secretions through which the virus can be transmitted. Husbandry methods in SE Asia where domestic flocks are often allowed to mix freely with wild birds, especially waterbirds will have facilitated the transmission to such birds, leading to several reported instances of die-offs.
The H5N1 virus seems to be spreading, with recent outbreaks in China, Kazakhstan, Mongolia, regions of Russia and countries around the Black Sea, on top of the spread through Asia since the end of 2003. It is not yet entirely clear how the disease is spreading, but clearly there is a possibility that migrating waterbirds may be involved.
The situation is evolving rapidly from day to day, and our position on the disease and proposed control measures will continue to evolve as new data emerge. The points below are based on the best information available on 14 October 2005:
The most recent outbreaks suggest that migratory birds may have transmitted the disease between countries or regions. Although this link has not been proven we cannot ignore the possibility. Movements of domestic poultry, another possible transmission route, have been largely implicated in the spread of the disease in SE Asia.
There have been no recorded instances of transmission of the disease between infected wild birds and humans. The H5N1 virus strain is not currently contagious between humans and most human cases to date have been associated with close contact with infected domestic poultry. The risk of a human contracting the disease from a wild bird is remote, unless there was excessive close contact with infected birds and their excreta.
Culls of wild birds are highly unlikely to stop the spread of the disease and, are extremely difficult to implement. This view is shared by the World Health Organization, Food and Agriculture Organization of the United Nations, the World Organisation for Animal Health and the UK Government. Indeed, culls have the potential to make the situation worse by dispersing infected individuals and stressing healthy birds, making them more prone to disease. Moreover, it would divert resources away from important disease control measures.
The most efficient control techniques involve improved biosecurity, primarily of the poultry industry, to reduce the likelihood of contact between domestic stock and wild birds or infected water sources. This needs to be coupled with swift and complete culls of infected poultry flocks in the event of an outbreak. Further measures that should be considered include stricter controls on wild bird markets, and movements of domestic poultry. Such measures should be introduced worldwide. Countries currently free of the disease should consider a ban on imports of domestic poultry and wild birds for the pet trade from affected regions. Preventing public access to infected sites is also clearly a sensible precaution.
It is important that discussions of the issues relating to avian influenza should differentiate between the real problems caused by the spread of the disease within bird populations, especially within the poultry industry, and the theoretical risks of a human pandemic, which might not happen.
We fully recognise the potential for a human pandemic should the current viral strain increase its transmissibility through mutation or reassortment, thus facilitating human to human transfer of the disease, and in the absence of swift measures to safeguard public health. We also recognise the impact the current strain is having on local economies forced into culls of domestic flocks, and the potential for greater financial impact on the poultry industry.
In addition to the impact of the disease on economics and livelihoods, and the potential impacts for human health, there are also potential implications for conservation. For instance, it is estimated that somewhere between 5% and 10% of the world population of the bar-headed goose Anser indicus perished in the recent outbreak in China.
Although there is a risk that migrating birds could bring H5N1 to the UK (mainly through movements of ducks from Siberia), at present, we consider that risk to be low, and even if this were to occur, the risk to humans would be negligible.
The World Heath Organization (WHO), The Office International des Epizooties (OIE) and the Food and Agriculture Organization (FAO) all concur that “the control of avian influenza infection in wild bird populations is not feasible and should not be attempted.” www.who.int/csr)
The following species which come to the UK from Russia have been targeted for special surveillance: European White-fronted Goose, Wigeon, Teal, Mallard, Pintail, Shoveler, Tufted Duck, Gadwall and Pochard.[BH1]
BTO, RSPB and WWT scientists have been advising Defra on how to undertake surveillance work to assess the occurrence of avian influenza viruses within the UK's wild bird populations. The press release relating to these discussions is on the Defra web-site: (http://www.defra.gov.uk/news/2005/051011b.htm)
The risk of infected birds arriving in UK will depend on what proportion of birds have come into contact with the infection, the transmission rate of the virus and the likelihood that an infected individual could undertake a long-distance migration. Currently these factors are difficult to quantify.
BTO, RSPB and WWT have issued guidelines to birdwatchers. These are available on the websites of all three organisations.