Prospects for Elimination of Bancroftian Filariasis by Mass Drug Treatment in Pondicherry, India: A Simulation Study

Abstract

LYMFASIM, a microsimulation model for transmission and control of lymphatic filariasis, was used to simulate the effects of mass treatment, in order to estimate the number of treatment rounds necessary to achieve elimination. Simulations were performed for a community that represented Pondicherry, India, and that had an average precontrol microfilariae (MF) prevalence of 8.5%. When ivermectin was used, 8 yearly treatment rounds with 65% population coverage gave a 99% probability of elimination. The number of treatment rounds necessary to achieve elimination depended to a large extent on coverage, drug efficacy, and endemicity level. Changing the interval between treatment rounds mainly influenced the duration of control, not the number of treatment rounds necessary to achieve elimination. Results hardly changed with alternative assumptions regarding the type of immune mechanism. The potential impact of mass treatment with a combination of diethylcarbamazine and albendazole is shown under different assumptions regarding its efficacy. Human migration and drug resistance were not considered. Results cannot be directly generalized to areas with different vector or epidemiological characteristics. In conclusion, the prospects for elimination of bancroftian filariasis by mass treatment in Pondicherry seem good, provided that the level of population coverage is sufficiently high.

LYMFASIM, a simulation model for predicting the impact of lymphatic filariasis control: quantification for African villages

“…As previously shown, post-control predictions depend heavily on assumed coverage and compliance patterns (Plaisier et al 2000 ;Stolk et al 2003 ; # The default assumption is that this variation occurs randomly between treatments. The sensitivity analysis considered the alternative assumption that variation occurs systematically between individuals and that there is no variation within individuals.…”

Post-Mass Drug Administration Transmission Assessment Survey for Elimination of Lymphatic Filariasis in La Ciénaga, Dominican Republic

“…6 Modeling data generally support these timelines, but also suggest that interruption can be achieved sooner depending on other factors including baseline prevalence, treatment coverage, drug selection, and vector control. 8,9 La Ciénaga had a favorable combination of low baseline transmission (10.7% antigen prevalence; 2.5% mf prevalence), potent drug combination (albendazole-DEC), concurrent environmental improvements in the area, and periods of albendazole monotherapy MDA for STH. However, any direct synergy would be limited to the school age population.…”

2.4 Program Implementation

“…Social mobilization is therefore of paramount importance to get communities to participate in the MDA. Model simulations indicate that high coverage, likely more than 80% of the total population, is essential during each annual MDA for interruption of transmission to be attained after five years; 8 indeed, most areas in countries where social mobilization has not been accorded much importance have shown poor treatment coverage. It is therefore important that effective social mobilization is maintained throughout the duration of MDA.…”