Since that time sporadic cases have appeared in the literature.

Both smaller outbreaks and sporadic cases have been reported from all the countries above.

It was a different strain of the disease, possibly a sporadic case.

But the reality is that sporadic cases have continued to occur through this weekend.

Sporadic cases are seen in patients in their 20s or early 30s.

The condition is usually congenital, but sporadic cases have also been reported.

While sporadic cases are common, he said, the recent numbers are higher than usual.

There were also sporadic cases of polling stations failing to open on time.

"You have to discard the hypothesis that these are merely sporadic cases we haven't seen before."

If that was the case, he said, the number of sporadic cases found in Britain since 1994 should have shot up; they have not.