Prevalence of lymphatic filariasis in the Northeastern States of India, with particular reference to Assam and prospects of elimination.

India is committed for the elimination of lymphatic filariasis (ELF) by 2020. Efforts were made to achieve this goal across the country during the last 10 years or so, and data thus generated reflect both the success and weaknesses of the ELF programme. India is contributing highest load of Lymphatic Filariasis (LF) infection to the global scenario, thus facing a massive challenge to make ELF programme a success. In this endeavour, the implementation of single annual dose of diethylcarbamazine citrate (DEC) and albendazole (Alb), in more than 250 endemic districts of the country for 8–10 years in a row, speaks volumes about the daunting commitment of the Government of India towards this programme. Apart from ensuring consistency in delivery of drugs for LF, the mapping of the areas which are still not covered under mass drug administration (MDA) is also a challenge for the programme managers. Data on endemicity of the LF are lacking specially from northeastern states of India.

In the northeastern region, which comprises eight states, only Assam is known as the endemic state for Lymphatic Filariasis (Anonymous, 1991) and, therefore, mass drug administration for ELF is being implemented only in this state. Of the 35 districts of Assam state, at least seven are endemic for LF and received MDA. Though, after several rounds of MDA, declining trend of microfilaria (mf) rate had been noticed in many districts of Assam, however, few districts still continued to report mf rate higher than the cutoff level of 1%. Unlike many parts of the country, LF is not uniformly distributed in the endemic districts of Assam. The tea garden worker population reports high microfilaria carriers, while the non-tea garden population records significantly low mf rate. As a result a district may report mf rate less than 1% and not qualify for MDA, whereas the population concentrated in the tea garden areas of the same district, which is sizeable in number, depicts mf rate as high as 5% even after several rounds of MDA (Khan et al. 2015). Therefore, ELF programme in northeast India needs a special attention to cover this vulnerable population with MDA for the success of the ELF.