Fig 1.
Random variables associated with components of the transmission cycle (top) and their successive sums (bottom).
On the top, the intrinsic incubation (IIP), human-to-mosquito transmission period (HMTP), extrinsic incubation period (EIP), and mosquito-to-human transmission period (MHTP) are shown from left to right, with the latter two parameterized for a temperature of 30°C. On the bottom, random variables for the elapsed time between inoculation of the primary infection and each event in the transmission cycle is shown in successive order from left to right.
Fig 2.
Relationships between temperature and entomological parameters (A) and epidemiological quantities (B-D). The thick solid (dashed) line in B shows the mean (median) generation interval at each temperature, and colors indicate the probability density of generation intervals at a given temperature (red to yellow = low to high). Contours show probability density values in intervals of 0.05. Colored surfaces in C and D show how temperature and mosquito emergence rate λ affect R0 and r (red to yellow = low to high), respectively. Black planes in C and D indicate the combinations of temperature and λ values for which R0 and r fall above or below threshold values (1 or 0, respectively). The thick black lines in C and D show the temperatures at which either R0 or r is maximized for a given value of λ. For comparison, the thin line in D indicates temperatures at which R0 is maximized.
Fig 3.
Temperature at which r peaks across a range of mosquito emergence rates λ, obtained by solving for r with 1,000 simulations of R0 based on Monte Carlo resampling of its three temperature-dependent parameters μ(T), n(T), and a(T) and applying Eq (1).
The solid line is the median r at each λ value, and the shaded region shows the 95% confidence interval of r conditional on λ.
Fig 4.
Relative contributions of the generation interval (blue) and the basic reproduction number R0 (orange) to temperature-driven changes in epidemic growth rate r.
Temperature changes are considered in 0.1°C increments and assume λ = 0.2. See S1 Fig for consideration of alternative λ value.
Fig 5.
DENV epidemic growth rate, r, for high (red) and low (blue) mosquito densities based on our full model and other approximations.
The top panels show comparisons of the full model estimates (solid lines) with those based on temperature independent, exponentially distributed (A) and fixed-length (B) generation intervals (mean = 16 days [34]) (dashed lines). The bottom panels show comparisons of estimates of the full model (solid lines) with those based on exponentially distributed (C) and fixed-length (D) generation intervals (dashed lines), with their mean values at each temperature set to the corresponding mean from the full model.
Fig 6.
Epidemic growth under an exponential model with values of the epidemic growth rate r ranging from 0.01 to 0.05 for a duration of 180 days.