Table 1 Role of hosts in pathogen epidemiology and their participation in maintenance and transmission functions

Target host

- The population of concern to the observer [10]

X

- Human populations (for zoonoses)

- Domestic populations

- Threatened wildlife species

Maintenance host population

- Hosts in which the pathogen persists even in the complete absence of transmission from other hosts [12]

X

(X)

- Brush-tailed possums for bovine tuberculosis in New Zealand [12]

- Population larger than the critical community size (i.e. size under which the pathogen cannot be maintained in the community) in which the pathogen persists [10]

- White-footed mouse (Peromyscus leucopus) for Lyme disease in the United States [6]

Maintenance host community/Maintenance host complex

- One or more epidemiologically connected populations or environments in which the pathogen can be permanently maintained [10]

X

(X)

- Anatids for avian influenza viruses worldwide [24]

- Any host complex in which disease persists indefinitely is a reservoir [12]

- Amphibian sp. for the trematode Ribeiroia ondatrae [18]

- Host for which cross species transmission and inter-species transmission are high [14]

Bridge host

- Non-maintenance host population able to transmit a pathogen from a maintenance host/complex to the target population, otherwise not or loosely connected to the maintenance complex (this manuscript)

X

Previous related definitions:

- Little studied so far

- Source population: any population that transmits infection directly to the target population [10]

- Red deer and domestic pigs for bovine tuberculosis in New Zealand [12]?

- Liaison host: incidental hosts that transmit pathogens from a reservoir to another incidental host [11,15]

- Peri-domestic birds such as swallow sp., sparrow sp., etc. [23]

- Spatial vector: host that transport the pathogen to target populations in new locations [12]

- Temporal vector: host that can transmit the pathogen to target species across temporal scale [12]