Dead-end hosts

Definition

A host species in which a pathogen can replicate or survive but from which transmission to other hosts is biologically impossible, typically because the necessary vector or transmission stage cannot be produced or acquired. Unlike reservoir hosts, dead-end hosts do not maintain or amplify the pathogen cycle in nature; they represent terminal branches in transmission networks.

Etymology

Example

Humans are dead-end hosts for West Nile virus: mosquitoes (Culex spp.) transmit the virus to people, but subsequent human-to-mosquito transmission is rare because viremia in humans is usually insufficient to infect feeding vectors.

Synonyms

• terminal host
• incidental host

Related Terms

• reservoir host
• amplifying host
• vector competence
• spillover
• Zoonosis
• bridge vector

Usage Notes

Contrast carefully with reservoir host and amplifying host, which actively perpetuate transmission. In medical entomology, identifying dead-end hosts is critical for assessing human disease risk and for distinguishing epizootic from enzootic cycles. The term is sometimes used loosely for hosts that rarely transmit; strict usage requires biological impossibility of onward transmission. Plural form is standard; singular "dead-end host" is acceptable.