The number of Israelis found to have contracted or to have recovered from the H1N1 (swine) flu rose to four on Sunday when a 20-year-old woman hospitalized at Tel Aviv's Sourasky Medical Center with flu-like symptoms after returning from Mexico via Madrid was found positive for the virus. Also, a three-and-a-half-year-old girl who had flu-like symptoms after returning from Mexico was isolated at Jerusalem's Shaare Zedek Medical Center on suspicion of having contracted the disease there. The Health Ministry said that because she had spent time after her trip in a home nursery with four other children, the nursery has been closed until further notice to prevent any possible spread of the virus. Prof. Manfred Green, dean of the University of Haifa's School of Public Health and formerly the director of the National Center for Disease Control, said that initially Israeli health authorities were concerned about the unusually high reported rates of flu deaths in Mexicans - including many healthy and young people, which is not characteristic of ordinary flu. The World Health Organization gave daily briefings and set the alert to the next-to-the-highest level. However, today these morality figures appear to have been highly exaggerated by the Mexican authorities, whose health system is not among the best. Now, Israeli epidemiologists are worried not about an unusually high mortality rate but about its relatively quick spread to other countries due to airline passengers on tours going home from Mexico. "The damage from media exaggeration may be larger than the damage from the disease itself," said Green before the opening on Wednesday of a University of Haifa conference on avian flu. He said the new flu strain combined human, pig and avian viruses and that it would take months before a vaccine was prepared and marketed to fight the strain. But it was not more virulent than ordinary flu strains for which annual vaccines are available each winter, he declared. Flu of all kinds primarily posed danger to the very young, the old and the chronically ill with weak immune systems, he said. In addition, healthy workers who contracted flu miss work, thus causing economic problems. Some of the media exaggerated the story and made it more dramatic, causing unnecessary panic, Green said. "We must prevent the 'Crying Wolf' phenomenon," he said. "Flu viruses keep changing all the time, without giving early warning. We don't have a good explanation how this happens. I have no doubt that the our future direction will increasingly have to be investment in advanced vaccines." Meanwhile, the union of lab workers and microbiologists demanded that the Health Ministry open an additional virus-screening lab in Jerusalem or Haifa to help with the testing of blood or saliva from arrivals at Ben-Gurion Airport as well as those who have been in contact with those confirmed to have had the H1N1 virus. The lab currently handling the tests is at Sheba Medical Center at Tel Hashomer.