The UK Department for Environment, Food, and Rural Affairs (Defra) revealed that genetic coding within strains of the HN51 virus found at both outbreaks matched 99.96 per cent, suggesting a direct relation between contamination. With the possibility that the cross contamination may be responsible for the link, the EU may yet be forced to review existing food safety measures, including more restrictive trade measures. The EU has currently forbidden member states from banning Hungarian poultry products after satisfying itself that the country's officials had successfully carried out the blocs avian influenza directive to prevent a further spread of the outbreak. Under the current directive any member state that discovers a bird flu outbreak must impose a 3 km quarantine zone around the infected area. This must then be accompanied by a further 10 km surveillance zone in which animals must remain indoors and are unable to be moved to any location other than the slaughterhouse. The H5N1 strain is usually carried by wild birds and then transmitted to domestic flocks. In rare cases the deadly disease can be transmitted to humans.H5N1 has so far infected 271 people worldwide, of whom 166 have died, mainly in Asia. Ian Brown, chief avian virologist at the UK's vetinary lab authroity (VLA), said that the similarities in both diseases may be the result of cross contamination of infected turkey between the countries. "Although other European viruses have shown close relationships to these viruses, these levels of identity are much closer than with other Asian lineage H5 viruses for which data is available, including those isolated from wild birds in Europe in 2005/06," he said. As a result he added that: "current working hypothesis suggests that poultry to poultry transmission is the most likely source of the outbreak. However, I must reiterate that we are not discounting any line of enquiry and this is an ongoing investigation." Despite the link, Dame Deirdre Hutton of Britain's food standard agency played down fears that consumers in both countries were in serious danger due to the avian influeanza outbreak. "The investigation so far has not found anything that raises the risk to public health", she said. "It is still a possibility that infected poultry has entered the food chain but the risk to public health remains low."