On the other hand, some infectious agents are highly virulent.

In some ways it resembles a highly virulent and extraordinarily accelerated form of multiple sclerosis.

This antigenic shift could cause the formation of a highly virulent virus.

The plague is highly virulent and eventually leads to major organ failure.

But in nine months it mutated to a highly virulent one.

High levels of toxins were produced with isolation of highly virulent.

This highly virulent virus was later discovered to be a chimaera of two distinct begomovirus species.

Intensive farming may be creating highly virulent avian flu strains.

Birds over eight weeks are resistant to challenge and will not show clinical signs unless infected by highly virulent strains.

It is highly virulent in domestic birds and wild birds.