But officials do not know how the child was infected.

Within a week of his death, it was clear that the couple's two children had also been infected.

In most of these cases, the children were infected by their mothers.

No child between the ages of 4 and 11 was infected.

If the child has already been infected, treatment can make the disease less severe.

Without this vaccine, most children will get infected by the time they are about 5 years old.

An estimated 170,000 adults and children were infected at the end of 2004.

It also means that many spouses and children are infected.

What remains puzzling, though, is why so many children have been infected.

Almost every child has been infected with rotavirus by age five.