104

■Appendices

Figure 8: Density visualization of important areas in the map created with the most

common terms in the titles and abstracts of the included papers. The density ranges from

red highly dense points to low dense points [14].

this model,

dSh

dα ^{= −hSh +rIh +γRh}

dIh

dα ^{= hSh −rIh −qIh}

(5.B.1)

dRh

dα ^{= qIh −γRh,}

an infected person can recover at rate r and move directly to the susceptible class, or may

slowly acquire immunity at rate q. They introduced immunity factor in their model by sub-

tracting the people who lost immunity, γRh from the immune class Rh and adding them to

the susceptible class Sh. The plot of the simulated solution of the model Equation 5.B.1,

given in Figure 5.2, reveals how prevalence changes with respect to age for different val-

ues of force of infection. With a higher rate of infection (h = 5/yr), typical for endemic

areas, malaria prevalence rises speedily at young age up to a peak, from where it gradually

declines to a low level in adulthood, as a result of the increase in immunity. Contrarily,

prevalence is shown to have an insignificant dependence on age for low force of infection

(h = 0.05/yr). This model predicts that in highly endemic areas, the prevalence rapidly rises