Once the transmission rates are defined, the next step is to define the force of infection, which is the rate of new infections in each of the 6 sub-populations defined by the 3 age classes and 2 sex classes:λK1=λK2=βKI*N(2a)λY1=βK(IK1+IK2)+βF(IY1+lIA1)+βX1(IY2+k2IA2)N(2b)λY2=βF(IK1+IK2)+βX2(IY1+k1IA1)N(2c)λA1=βK(IK1+IK2)+lβF(IY1+lIA1)+k1βX1(IY2+k2IA2)N(2d)λA2=βK(IK1+IK2)+k2βX2(IY1+k1IA1)N(2e)where I* = IK1 + IK2 + IY1 + IY2 + IA1 + IA2. This evidence concerns the gene INSM1 and infection.