An unusual pattern of avian flu cases in Egypt — almost all are in toddlers, all of whom have survived — has led some flu-tracking Web sites to speculate that dozens of silent cases are circulating there.That would be an alarming development, but other experts, including those at the World Health Organization, say such fears are exaggerated. Although thousands of Egyptians have rushed their children to hospitals this flu season, there is no evidence yet of asymptomatic avian flu cases or any significant mutation in the H5N1 virus.
“Right now, it’s all hot air,” said Dr. Robert G. Webster, a flu expert at St. Jude Children’s Research Hospital in Memphis. “I hope to hell it’s not happening, because it would mean the virus is adapting to humans. But there’s not a shred of data.”
Bird flu has faded from world headlines because it has not caused a pandemic. But the disease is still circulating in poultry in Egypt, Indonesia, China, Vietnam and along the India-Bangladesh border. It has mutated into at least 10 strains and occasionally infects humans.
An April 8 Reuters article from Cairo quoted a visiting W.H.O. expert saying his agency feared “something strange happening in Egypt” and would help the government test the blood of healthy people for antibodies this summer. Antibodies to the flu would indicate they had recovered from silent infections.
But a W.H.O. spokesman said privately that the agency was just helping the Egyptians with a long-planned study and the article had “jumped the gun.”
Translations of Egyptian media reports posted on flu-tracking sites say dozens of suspected cases have been hospitalized, but some seem to confuse avian flu with seasonal flu and even confirmed poultry cases. The Egyptian health ministry, which works closely with a United States Navy laboratory based in Cairo, has confirmed 15 human cases this year, with no deaths; almost all were in young children.
Dr. Nikki Shindo, a W.H.O. medical officer who works in Egypt, said the surge in toddler cases and survivals had a possible explanation. The government has loudly warned its citizens to avoid sick poultry and has trained doctors in remote clinics to give Tamiflu quickly and move cases to state hospitals, where treatment is free. In a country where chickens are both kept as pets and eaten, toddlers still touch dying birds but poultry workers would not.
EgyptÂ’s outbreak response contrasts sharply to IndonesiaÂ’s, where the sick often take herbal medicine first and where rural clinics lack Tamiflu, she said.
Dr. Arnold S. Monto, a flu expert at the University of Michigan School of Public Health who also teaches in Egypt, said even geography helps. All cases are along the Nile and easily moved to Cairo, while travel among IndonesiaÂ’s thousands of islands is slower. Also, he said, the government has been more aggressive since it was criticized by opposition parties for not wiping out the poultry epidemic that began in 2006.
Henry L. Niman, a biochemist who tracks flu mutations, has speculated that a mild strain of H5N1 is more common in Egypt than has been found because nasal swabs for flu are inaccurate. He noted that mild cases were found in Qena, Egypt, in 2007, and has called for more testing and for releasing the genetic sequences of strains found in both poultry and people.
Dr. Tim Uyeki, a flu specialist at the Centers for Disease Control and Prevention in Atlanta, said there had been mild cases of H5N1 among children in several countries. There have also, he said, been studies in Indonesia, Thailand, Cambodia and Nigeria similar to the one proposed for Egypt in which the blood of cullers, poultry workers and relatives of sick people has been tested.
“Those are the ideal people to look at,” he said. “And there was zero or extremely low prevalence of antibodies,” meaning silent infections were very uncommon.