A study suggests that most people exposed to avian flu do not become seriously ill and recover in a few days, even as a surge in suspected human bird-flu cases is raising alarm in Turkey.
The Swedish study, published yesterday in Archives of Internal Medicine, said a survey of Vietnamese showed that most people who handled dead or sick poultry reported mild flulike symptoms but did not have the severe reaction health officials said could sweep the globe.
Dr. Anna Thorson of the Karolinska Institutet in Stockholm, who led the study, said that although survey subjects were not tested for the H5N1 avian-flu virus, researchers think the participants had it. Researchers also said concern about a pandemic has been fueled by the fact that only the worst human cases have been reported to health officials since the 2003 outbreak in Asia.
“The verified human cases of highly pathogenic avian influenza in Vietnam may represent only a selection of the most severely ill patients,” the study says.
But Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said yesterday that he has reservations about the study. He said that without blood tests it is impossible to know whether the people had influenza, much less avian influenza.
“There isn’t enough sufficient specific data to draw any conclusions as to the prevalence of bird flu in that community,” Dr. Fauci said.
Dr. William Schaffner, chairman of the Department of Preventive Medicine at Vanderbilt University Medical Center, called the study “terribly imprecise.”
“There need to be more studies like this, but with laboratory confirmation,” the Nashville specialist said.
H5N1, which primarily affects birds, has epidemiologists concerned because about 50 percent of humans who develop avian flu as a result die, according to World Health Organization (WHO) data. By comparison, about 0.5 percent of the U.S. population that gets flu dies in an average season.
Specialists fear the H5N1 virus will mutate and become easily contagious between humans.
If the Swedish findings prove to be correct, Dr. Schaffner said, mortality from bird flu would be “more consistent” with that of other infectious diseases. “But at this point, there is no way to tell,” he added.
The dispute over the study comes as the number of suspected and confirmed bird-flu cases in Turkey continues to grow. Wire reports yesterday indicated five new cases of positive tests for H5N1, bringing the number of suspected human cases in that country to 14.
But WHO said it knows of only four laboratory-confirmed cases. Two Turkish siblings have died, the organization said, and the possibility of a third sibling death from H5N1 in the family is being investigated.
Yesterday, a crowd mobbed a health minister in the remote town of Dogubeyazit in rural eastern Turkey, where the first bird-flu deaths outside East Asia occurred last week.
The reported new cases involve youths in four provinces, raising concerns that bird flu is spreading westward across Turkey toward Europe. Dr. Guenael Rodier, a senior WHO official for communicable diseases, said the human infections seem to have resulted from direct contact with infected domestic birds.