Past exposure and the dynamics of lymphatic filariasis infection in young children.
This study utilizes parallel, longitudinal entomological and parasitological data collected during a 5-year vector control programme in Pondicherry, South India, to quantify Wuchereria bancrofti transmission from the vector to the human population. A simple mathematical model, derived from the standard catalytic model, is used to examine the hypothesis that current infection prevalence in young children is a dynamical function of their cumulative past exposure to infective bites. Maximum likelihood fits of the model to the observed data indicate a constant child infection rate with age, above a threshold representing the pre-patent period, or equivalently, the cumulative biting intensity required to produce patent infections. Extrapolation of the model allows the crude estimation of the equilibrium microfilaria age-prevalence curve due to control. The results suggest that vector control alone may have little impact on the overall age-prevalence of infection even when sustained for long periods. These observations are discussed in terms of the likely impact of density dependent mechanisms, such as acquired immunity, on model predictions.
Srividya
A
A
Vector Control Research Centre, Indira Nagar, Pondicherry, India.
Das
P K
PK
Subramanian
S
S
Ramaiah
K D
KD
Grenfell
B T
BT
Michael
E
E
Bundy
D A
DA
D000367:Age Factors; D000818:Animals; D002648:Child; D002675:Child, Preschool; D004605:Elephantiasis, Filarial / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008137:Longitudinal Studies; D008954:Models, Biological; D009032:Mosquito Control; D015995:Prevalence; D014958:Wuchereria bancrofti