More recently evolved viruses cause epidemics and pandemics - and it is these that history records.

Many different things combine to cause epidemics of disease.

They're especially-unpleasant viruses which have caused epidemics in Africa.

It also will continue to cause periodic epidemics in areas such as South America with higher, but still inadequate, vaccination rates.

And it would have had to affect a broad array of species without causing epidemics in humans.

Government workers vaccinated villagers but feared that large numbers of bodies could cause epidemics.

There is also some danger from mutant viruses, which arise naturally although they rarely cause epidemics.

Type C flu viruses do not cause epidemics.

The disease has caused epidemics in the past.

Since then, the four types have caused epidemics affecting millions.