Table 1.

Empirical examples from the published literature of beta and R ₀ measured in host populations differing in size, indicating the empirical observations and the likely mean-field scaling model.

Host-pathogen system	Empirical observations	Model supported	Reference
Humans-measles Humans-pertussis Humans-diphtheria Humans-scarlet fever	Found R 0 to be relatively invariant across population sizes.	Frequency dependent	[15]
Humans-smallpox	Transmission was inverse of population size	Frequency dependent	[58]
House finches-mycoplasma	Transmission was independent of flock sizes	Frequency dependent	[59]
Pigs-Aujeszky's disease virus (ADV)	R 0 was invariant across different population sizes	Frequency dependent	[21]
Harbor seals-phocine distemper virus (PDV)	Density-dependent scaling did not explain differences in transmission between different-sized seal haul-out sites	Frequency dependent	[20]
Rana mucosa-chytridiomycosis	Transmission rate increases and saturates with density of infected individuals	Frequency dependent	[33]
Tasmanian devil—devil facial tumor disease	Maintenance of high prevalence following population decline	Frequency dependent	[34]
Brushtail possums-leptospira interogans	Density-dependent model fit experimental infection rates	Density dependent	[60]
Elk-brucellosis	Population density was associated with an increase in seroprevalence but could not differentiate among linear and nonlinear effects of host density.	Nonlinear density dependent	[61]
Rodents-cowpox	Both models fit to incidence time series; support for both equivocal.	Frequency and density dependent	[22]
Rodents-cowpox	Transmission term lies between density- and frequency-dependent and varies seasonally.	Model is intermediate	[11]
Indian meal moth-granulosis virus	A decline in transmission with increasing density of infectious cadavers	Neither	[26]
Possum-tuberculosis	Transmission did not fit frequency- or density-dependent models	Neither	[62]
Tiger salamander-Abystomatigrinum virus	Transmission was best modeled by a power or negative binomial function, that is, nonlinear density dependence.	Neither	[63]
Badgers-Mycobacterium bovis	Negative relationship between host abundance and infection prevalence	Neither	[64]