Table 1

Quantification of several key biological parameters in the EPIFIL and LYMFASIM model variants for Pondicherry, where Wuchereria bancrofti is transmitted by Culex quinquefasciatus. Values in bold-face were estimated indirectly by fitting the model outcomes to observed epidemiological data; other values were quantified directly from literature, theory, and analysis of local data

Parameter

EPIFIL

LYMFASIM

Anti-L3 immunity

Anti-fecundity immunity

Parasite lifecycle

Average adult worm life span in years

8 ^a

10.2 ^b

11.8 ^b

Average mf life span in months

10 ^a

10 ^c

10 ^c

Premature period in months

-

8

8

Exposure variation by age

Exposure at age zero as fraction of maximum exposure

0

0.26

0.40

Age in years at which maximum exposure is achieved

9

19.1

21.3

Density dependence in mosquitoes

Maximum number of L3 larvae that can develop in mosquitoes at high mf intensities

6 ^d

6.6 ^e

6.6 ^e

Acquired immunity

Duration of acquired immunity in years

lifelong

9.6 ^f

11.2 ^f

Other parameters

Monthly biting rate

5760

2200

2200

Proportion of L3 larvae in mosquitoes that enters the human host when a mosquito bites

0.414*0.32 = 0.13

0.1

0.1

Proportion of inoculated L3 larvae that develops successfully into adult worms (x10^-3)

0.113

1.03 ^g

0.42

Mf production per worm

2

0.61 ^h

4.03 ^{h, i}

- Not considered in the model; mf, microfilaria.

^a Assuming an exponential distribution.

^b Assuming a Weibull distribution with shape parameter α = 2.

^c Assuming an exponential distribution, approximated with discrete time steps.

^d Exponential saturating function with initial increase from zero = 0.047.

^e Hyperbolic saturating function with initial increase from zero = 0.09.

^f Period in which the strength of the immune response is halved in the absence of boosting.

^g In the absence of anti-L3 immunity.

^h In the presence of at least 1 male worm, scaled to the number of mf per 20 μl peripheral blood.

ⁱ In the absence of anti-fecundity immunity.

Stolk et al. Filaria Journal 2006 5:5   doi:10.1186/1475-2883-5-5