The outbreaks in January on geese farms in the village of Lapistó (Csongrád county in southern Hungary) and then in Derekegyháza, nine kilometres from the first outbreak, were not much of a surprise as there had been outbreaks in 2006 in Hungary linked to wild birds [1,3]. The more recent outbreak on a large turkey farm in the UK (in Suffolk, southeast England) is the first to have occurred in the country, and so attracted more attention. It was initially suggested that wild birds were the source in the UK. If true, this would have been evidence for the possibility that, rather than being confined to wild birds in specific areas, the virus might once again have become widely disseminated in wild bird populations across the European Union (EU). This would have meant an increased health threat to poultry in the EU, particularly for small backyard flocks because of the difficulties of maintaining separation of wild birds and poultry. Due to the close contact between birds and backyard flock owners, the owners may also have been at a limited risk of infection [4,5].

However, the birds on the affected UK farm were housed in an enclosed biosecure unit with limited possibilities for contact with wild birds [2]. Additionally, the EU's extensive wild bird surveillance has not detected any positive H5N1 infected wild birds for several months (a very different situation from the early months of 2006) [6]. If the virus is present in wild bird populations within the EU, there is no evidence that it was widely disseminated.

The H5N1 specimens from affected birds in the Hungary and the UK were sent to the EU Community Reference Laboratory for testing and genetic sequencing where the genomes of the viruses from Hungary and the UK were found to be 99.96% similar [7]. The possible link between the two outbreaks is now the subject of intense investigation by EU, Hungarian and UK veterinary authorities to determine whether and how transfer could have taken place in either direction.

Protecting poultry and culling team workers a priority for health authorities
EU legislation requires that, following notification of a suspicion of an outbreak of a highly pathogenic avian influenza of any type, rapid containment measures are applied in the affected premises, including the culling of the flocks [8]. This was done in both Hungary and the UK [1,2]. In the UK, a large number of temporary workers were brought in quickly to manage the culling and disposal of over 160 000 birds. Applying the ECDC recommended precautions to protect the health of these poultry workers was highly labour-intensive for authorities. Workers need to be advised and instructed in use of personal protective equipment and offered antivirals [9]. This should happen before the urgent culling and disinfection work is carried out, after which the workers have to be followed up.

In 2003, there was a single fatal human case of influenza A/H7N7 infection (another highly pathogenic avian influenza virus) in a veterinarian in the Netherlands who was involved in controlling an outbreak on a farm. The patient had not taken measures to protect himself from infection [10]. This case and some milder illness in cullers and their families during the same outbreak demonstrated the necessity of stringent protective measures for people who have close contact with sick and recently dead birds affected by any highly pathogenic avian influenza [9]. The infection risk to culling teams from A/H5N1 is considered very low because, worldwide, there has not yet been a reported case of H5N1 disease in a poultry worker through occupational exposure, although there have been some occasional seroconversions observed among poultry workers in Asia 11].

There were a few coincidental mild respiratory infections among some of those involved in the control operations in the UK (influenza indices are increasing at present in parts of the EU) and there was concern that these symptoms could have indicated human H5N1 infections. Application of the national clinical algorithms determined that the cases did not fit many criteria but the patients were still tested for H5N1 and found to be negative [12,13].

Almost non-existent risk to general public – low but real risk for poultry owners in Europe
The risk to the general public from H5N1 in general and specifically from consuming meat and poultry products has been repeatedly considered to be minimal by authorities such as the the ECDC, the European Food Safety Authority, the World Health Organization International Food Safety Authorities Network (http://www.who.int/foodsafety/fs_management/infosan/en/) and national food safety agencies within the EU [16,17]. Guidance from these authorities always emphasises the importance of cooking and food hygiene but this is mostly to protect against other pathogens (Campylobacter, Salmonella and E. Coli O157) that are more common, better adapted to humans and much more infectious [18].

As for the possibility of H5N1 transfer in or on unprocessed food or fomites such as packing or clothing, the potential occupational health risk to workers in the food industry and those preparing food in the home and catering is currently being assessed, but is believed to be very low, as the virus remains poorly adapted to humans.

If there has been transfer of the H5N1 virus via poultry products or fomites (and at this stage these are only two of the possible options), this could mean more outbreaks within the EU. the threat would mainly be to the agriculture industry, but this could also cause considerable work for health authorities. Reduction in the already low risk to human health in Europe rests mainly on the stringent application of EU veterinary controls and application of biosecurity measures in every EU country that will prevent the virus getting into the domestic poultry [19].

Owners of small flocks have previously been assessed to be at low but real risk from A/H5N1 infection. These people still need to take the recommended precautions to protect their own and their family’s health (H5N1 is not the only potential infection health risk posed by birds) (Box). But the best defence for human health against the H5N1 influenza virus remains prevention and control of infection in poultry flocks.

Box. Key messages to poultry owners - 2006