There are increasingly frequent outbreaks, e.g. another serious one in Uganda in early 2001 (and occasional scares when suspected cases turn up in western Europe or North America - it takes less than a day to fly to either from an epidemic zone). We remain almost equally ignorant about the essential features of several other newly identified tropical hemorrhagic fevers. As humans encroach further on previously uninhabited wilderness areas of tropical rain forest we can expect to encounter other dangerous pathogens, perhaps many of them.