The Impact of Coinfections and Their Simultaneous Transmission on Antigenic Diversity and Epidemic Cycling of Infectious Diseases

Figure 2

Influence of simultaneous transmission of coinfections and efficiency of partial transmission from coinfections on the prevalence of single infections and coinfections. The effects of each simultaneous transmission rate (𝛽_𝑙) of coinfections of multiplicity are shown: panels (a) and (b) 𝑙=2; (c) and (d) 𝑙=3; and (e) and (f) 𝑙=4 while others remain fixed. Two efficiencies of partial transmission from coinfections are shown: 𝜙=0.5 (panels (a), (c), and (e)) and =2 (panels (b), (d), and (f)). Model parameter values: immunity period (1/𝜎)=10 years, transmission rate of single infection (𝛽₁)=1.0 day⁻¹, and infectious period (1/𝛾)=20 days; hence 𝑅₀=20; life span (1/𝜇) = 70 years, 𝑛=10, and 𝑚=4. Note that within panel (b) cyclical epidemics occur when 𝛽₂=0, 0.25, 0.5 day⁻¹ with interepidemic periods around 420 days. The maximum (with subscript 𝑀) and minimum (with subscript 𝑚) prevalence are shown.

(a) 𝜙=0.5, 𝛽₃=0.0, 𝛽₄=0.0

(b) 𝜙=2, 𝛽₃=0.0, 𝛽₄=0.0

(c) 𝜙=0.5, 𝛽₂=0.75, 𝛽₄=0.0

(d) 𝜙=2, 𝛽₂=0.75, 𝛽₄=0.0

(e) 𝜙=0.5, 𝛽₂=0.75, 𝛽₃=0.6

(f) 𝜙=2, 𝛽₂=0.75, 𝛽₃=0.6