The Health Ministry's Israel Center for Disease Control (ICDC) says it is remaining "calm but alert" regarding the avian flu that has affected tens of thousands of turkeys in four farms in the Negev and has required the killing of hundreds of thousands of them to prevent the disease from spreading to other birds. ICDC director Prof. Manfred Green said Saturday night that "for all intents and purposes," the strain that infected the poultry at Kibbutzim Ein Hashlosha, Holit and Nahshon and Moshav Sde Moshe is H5N1, which is deadly in poultry but has not mutated to a strain that causes human-to-human infection. He added that the chance that humans would be infected was "possible but very small," as modern farms place only a handful of workers in charge of hundreds of thousands of turkeys and chickens, with most of the work carried out by automated systems. Green estimated that only tens - not hundreds - of farm workers were in direct contact with the infected birds. "Only 160 or 170 people have been infected with avian flu in the whole world and about 100 of them have died - despite millions of birds infected and billions of people living in the 22 affected countries. The humans who were infected all lived and worked in very close proximity to the sick poultry." The three kibbutzim and one moshav, and a radius of three kilometers around each, have been placed under veterinary quarantine. The Health Ministry ordered the turkey flocks on all four farms destroyed, as well as all those in chicken, turkey, duck and geese coops within the quarantine radius. The culling process began over the weekend, with poison introduced into the poultry's drinking water. Death follows within minutes, after which their carcasses are buried in plastic bags deep in the ground. Essential personnel who do the culling are required to don suitable protective gear - masks, goggles and protective clothing - before entering the area. The government has assured farmers that they will receive compensation from the government for their financial losses. Dr. Moshe Haimovich, chief veterinarian of the Agriculture Ministry's Veterinary Service, said Saturday night that there was "excellent cooperation" between Israel, Jordan and the Palestinian Authority to prevent the spread of avian flu among poultry in the region. The Health Ministry said that avian flu was ruled out in four people hospitalized at Soroka University Medical Center in Beersheba and Barzilai Hospital in Ashkelon who did not feel well. The four, including two Israelis and one Thai national from Kibbutz Ein Hashlosha who worked in the poultry coops and came into regular contact with the infected turkeys, were under observation throughout Friday and were kept in the hospitals' isolation wards. Green said it was still not clear how the avian virus reached Israel. "We have not been informed of avian flu in poultry in the Gaza Strip. Perhaps infected poultry were smuggled into Israel," he said. The World Health Organization (WHO), meanwhile, announced the death of a 35-year-old Egyptian woman apparently from avian flu on Friday; blood samples were send to Britain to confirm the cause. The woman, identified as Amal Muhammad Ismail, was admitted to a hospital in the governorate's capital Qalyoub about two weeks ago, and was subsequently transferred to Cairo's Fever Hospital where she died. The woman, who lived dozens of kilometers north of Cairo, raised poultry in her home. Some of the birds had died of avian flu. After the announcement, the Egyptian TV news station broadcast informational films about avian flu. The WHO praised Israel for its fast action in dealing with the epidemic in poultry farms, including the isolation of the poultry facilities and health checks of workers. The spokesman for the department in charge of handling bird flu said the government's policy of transparency and reassuring the public were "encouraging." The European Union temporarily prohibited import of poultry products from Israel. The Health Ministry advised the public to eat only cooked poultry and eggs - the heat destroys the avian flu virus. People should be careful washing their hands, utensils and kitchen surfaces when they handle raw poultry and eggs. Raw poultry should be separated from cooked foods, as it always should be to avoid the spread of ordinary pathogens such as salmonella bacteria. Green could not confirm whether crows or cow herons had feasted on the bodies of dead and exterminated poultry at Holit, but he said that after birds die, the virus loses its ability to infect others. The Let Animals Live organization sent a plea to Health Minister Ya'acov Edri and Agriculture Minister Ze'ev Boim, asking that the culling be carried out in a humane way and that the suffering of the birds be reduced to a minimum. In Turkey, the organization noted, live birds had been placed in plastic bags and left cruelly to die from asphyxiation.