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

Figure 9

Numerical integration of (A.1) with the efficiency of single transmission from dual infection 𝜙(=𝜙_𝑎=𝜙_𝑏)=1.75, 1.76, and 1.77. The real parts of two identical eigenvalues of characteristic equation (A.6) increase with 𝜙 and passed through 0 at 1.76 while the real parts of other two eigenvalues decrease with 𝜙 and remain negative. The imaginary part of the dominant eigenvalue is 0.0154, 𝑇=410 days from (A.16), in agreement with the result shown in the graph. As we assume both strains are equal, the fractions of both single infections overlap. Other parameters are transmission rates 𝛽_𝑎=𝛽_𝑏=0.75 day⁻¹, 𝛽_𝑑=0.375 day⁻¹, infectious period (1/𝛾_𝑎=1/𝛾_𝑏=1/𝛾_𝑑)=2 days, immunity period = 3 years, and life span = 55 years.

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