There is more evidence that children may be more susceptible than adults to the avian flu virus.

A recent report by the World Health Organization analyzed a recent outbreak of avian flu cases in Turkey in which only children were infected. In all, 10 children between the ages of three and 15 years of age were infected, and four of them died.

In most of the cases, the families kept live poultry at home, which led researchers to conclude that the parents or other adults at home were also likely exposed to the avian flu virus, yet they did not develop any symptoms of the flu.

"Even though both children and parents had most likely been exposed to the same source, infection was documented only among children aged less than sixteen years," states the report, which appears in the WHO's Weekly Epidemiological Record this week. "It suggests that age-related factors may influence susceptibility to the disease."

Many of the documented cases of avian flu have been in children, which has led researchers to examine whether or not children are at greater risk for the disease based solely on their age or the fact that in many rural countries children are the main caretakers of poultry at home.

Avian flu experts have predicted that in the event of a major outbreak in the U.S., a quarter to a third of the deaths could be children.