Fleas are ectoparasitic blood-sucking insects with the ability to jump, which commonly infest wild and domestic animals (mainly dogs and cats) but also humans.
Besides Yersinia pestis (see plague) the Yersinia group of bacteria also includes two species frequently causing illness (mainly enteritis) in humans; Yersinia enterocolitica and Yersinia pseudotuberculosis.
Botulism is a serious paralytic illness caused by a nerve toxin produced by the bacterium Clostridium botulinum. The disease may occur after eating foods containing the toxin or due to development of the spores within the intestine of young children or within wounds.