as you all might know, avian influenza -so called bird flu- cases are spreading around the world, in particular in south-east asia, africa and europe. in BirdLife Indonesia, we are interested with statement mentioned that wild birds play role in spreading the virus since they are migrating to other places in the world. hence, we believe that it’s too early to be mentioned. here is a FAQs about that matter, which is written by Pete Wood a.k.a my boss :D.

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Avian Flu is in the news again because of new human cases, new cases in wild birds in Europe and Africa, and direct action by some villagers against birds in their vicinity. The Indonesian Government’s action is in accordance with other national governments and has focused on surveillance, vaccination, destruction of infected birds, and regulating the keeping of domestic ducks and geese. However there continue to be some statements made by other parties that wild birds and particularly migratory birds play a major role in the spread of avian influenza (Highly Pathogenic Avian Influenza, HPAI). If this argument results in efforts to kill or drive away wild birds, it will waste scarce resources which should be focused on the vital job of detected and controlling Avian Flu in domestic fowl.

Here we review what is known about the spread of Avian Flu by wild birds.

Did HPAI come from wild birds?

No. Wild birds naturally have ‘flu’, just as humans do, and as with humans, the birds have some resistance and are not killed or made severely ill by the flu. These are called Low Pathogenic Avian Influenza viruses. The mutation to HPAI took place within domestic chickens and ducks. When wild birds are found to have HPAI, it is believed they have caught it from domestic birds.

Where did HPAI come from?

Scientists who have examined the genetic structure of the HPAI virus from different places have concluded that it first appeared in domestic birds in Guangdong province in south-east China in 1996. The Chinese authorities do not agree with this analysis.

Can wild birds contract HPAI?

Yes. There have been records of HPAI in 37 species of wild birds throughout the world. Twenty three of these species are water birds and 14 land birds. In two cases large numbers of birds have died, most geese and ducks, but apart from that there are no examples of the disease spreading widely in wild birds. In all other cases, only one or a few individual birds have been involved. It seems that ducks, geese and swans are most vulnerable to infection, either because of their biological similarity to domestic ducks, or because they feed in the same habitat that is used by domestic birds.

Can wild birds spread HPAI to domestic chickens and ducks?

If wild birds and domestic ducks and hens are in direct contact, or are contaminated with faeces or other waste, then disease could spread between them. The HPAI virus dies quickly if it is dry, but can survive for a long time (maybe 3 months) in wet conditions. The highest chance of transmission is between domestic and wild ducks which feed on the same wet areas (lakes, paddy fields etc). However wild birds are almost certainly not the main cause of HPAI infections – transport of chickens and chicken products is a much more likely route for direct transmission between flocks.

Are wild birds responsible for spreading HPAI over long distances?

It is very unlikely that wild birds play a role in spreading the virus over long distances. This conclusion is supported by several facts:

First, almost all of the wild birds that have been found with HPAI have been dead or dying. At the same time, over the last 2 years thousands of live wild birds in several countries have been tested and found to be negative. This suggests that when a bird catches the virus, it quickly becomes ill and dies. It cannot therefore fly long distances.

Secondly, the pattern of spread of HPAI does not fit the expected pattern if birds were the main agents of spread. For example, there was a big outbreak of HPAI amongst water birds in Quinghai lake in northern China in April 2005, but the birds which breed there do not come from South-east Asia (where HPAI is widespread) – they migrate from South Asia, where there has not been any report of HPAI.

Genetic analysis also suggests that bird migration does not play a major role in spreading the virus. The types of HPAI virus in China, Vietnam and Indonesia all have some unique characteristics, showing that they have been isolated for some time. If migratory birds were bringing the virus every year with their regular movements, the genetic make-up of the virus would be expected to be similar across the region.

The may be an exception for ducks. In laboratory experiments, it has been shown that some species of wild ducks do not get very ill when they are infected with the virus, and that they may be able to travel and shed the virus in their faeces. A similar situation maybe the case in Swans, large water birds which occur in Europe and Russia but not in South-east Asia. In January 2006 dead swans infected with HPAI were found in several European countries at about the same time. It is thought that they must have been infected at one place in Eastern Europe, and spread out over a wide area when they moved west to find warmer weather. So far however, there have been no cases of infection in other wild or domestic birds where the swans were found. It seems they were killed by the virus but have not passed it on to other birds, so their role as vectors is still unproven.

If not wild birds, how could the virus have spread?

The chicken industry itself is a huge global industry which depends on a constant supply of day-old chicks. There are massive movements of live chicks, adult chickens; meat and feed within and between countries, and all of these could cause the spread of HPAI. Even though many countries have banned chicken imports, there are many cases of smuggling. The patterns of spread of the virus in many cases follows the main transport routes, not the main wild bird migration routes. The Nigerian Government has blamed trading and smuggling for the outbreak of HPAI that started in January 2006 in Nigeria.

Other ways the virus might travel are through waterways and ponds contaminated with chicken faeces, in fish farms where chicken faeces are used as manure to enrich the water, and from fields where contaminated chicken faeces have been used as fertilizer.

What are European countries doing now that the virus has been detected?

So far HPAI has only been found in a few species of water bird, mainly swans, in Europe. European countries are increasing surveillance in the areas where the dead birds were found, and ordering farmers to keep chickens and ducks inside to avoid any contact with wild birds.

Why are European countries not shooting wild birds?

There are several reasons why international authorities (OIE, FAO) agree that killing wild birds is not useful as a way of stopping the spread of HPAI. The first is that, for all the reasons given above, wild birds are not likely to be the main cause of HPAI spreading. It is much more important to focus limited resources on surveillance of domestic birds, killing infected chickens and vaccinating flocks at risk, and stopping transport of sick birds, as well as minimizing the chance of contact between wild birds and domestic birds.

The second reason is that killing wild birds is very unlikely to be effective. Any attempt at trapping or shooting is more likely to make the birds scatter and spread over a wide area to escape persecution. If they are carrying the virus, then it will spread over a wider area as well.

What is the link between HPAI in wild birds and human deaths from ‘Bird Flu’?

There is no link. There is every indication that the cases of human deaths in Vietnam, Indonesia, Cambodia, China, Thailand, Iraq and Turkey are associated with direct contact between infected chickens and people. Most deaths have been in urban areas where there are few wild birds and no direct contact with water birds. It is also important to remember is also important to remember that the chance of catching the HPAI virus from a chicken is very small. Considering the millions of chickens which have been infected and have died or been killed in South-east Asia, thousands of people must have been exposed to the virus – and yet only a handful have become infected. Scientists have still not been able to explain why a very few people seem to be susceptible to the virus whilst most are not, but all agree that reducing contact with infected chickens is important.

What is the situation with HPAI and wild birds in Indonesia?

HPAI is now very widespread in chickens and other domestic fowl (ducks, turkeys etc) throughout Indonesia, having occurred in 2/3rds of the provinces. The hardest hit areas have been Banten, West Java, Jakarta, and Lampung.

There have been no cases of HPAI in wild birds in Indonesia. However the virus can change and it is important to monitor wild birds, especially ducks and geese.

Many species of water birds and land birds fly between Indonesia and Australia. Over 1 500 shorebirds have been tested in Australia by the World Health Organisation and Australian Department of Primary Industries without detecting any active flu virus . This suggests that migratory birds are not spreading HPAI between Indonesia and Australia.

Indramayu, on the north coast of West Java province, is well known as place where many water birds stop during their migration during the northern winter. At least two villages close to the shoreline used by the birds specialize in hunting, killing and cooking these wild birds to sell to the local market. The area is also a centre for poultry production, and 17 of 28 sub-districts in Indramayu Distrct have recorded outbreaks of Avian Flu in chickens. Recently Indramayu has been mentioned in the press because 3 people from one family contracted a disease suspected to be Avian Flu, and 2 of them later died. However experts do not believe that this infection has come from wild birds. The people who fell ill were from Cipedang, which is not a village where wild birds are hunted. If there was a risk of infection from wild birds it should be the people from the villages which do hunting, who have daily contact with wild bird blood and faeces, who are infected. In Cipedang the chickens had been dying of a disease similar to Flu Burung, and this is suspected to be the source of the infection in humans.

If it is thought that wild ducks might act as ‘carriers’ of the virus, what ducks migrate to Indonesia, and from where?

There are 18 species of ducks in Indonesia. Twelve of them are resident (do not migrate) and so could not play a role in transporting the virus over long distances. The other seven species which migrate do not come to Indonesia in large numbers, and mostly migrate only as far as north of Kalimantan and Sumatra. There have not been any cases of bird flu in wild birds, domestic birds or humans in the areas visited by these migratory ducks.

by Pete Wood/Knowledge Center BirdLife Indonesia

photo by Stephan Dobert/USFWS