Elimination of Lymphatic Filariasis in Goa: First Successful Transmission Assessment Survey in India

Goa is known to be endemic for bancroftian filariasis since 1952. Under National Filaria control programme, four control units, and six night clinics were functioning in the state. Programme to eliminate lymphatic filariasis was launched in 2004 in Goa, covering 1.54 million people. The microfilaria prevalence was 0.62% in 1996 but the state receives lot of migratory population from LF endemic areas. Nine rounds of MDA (five with DEC alone and four with DEC + albendazole) were completed. The reported coverage ranged from 91.4 % to 98.1% in different MDA rounds. Impact assessment in sentinel and spot-check sites has shown that in none of the sites microfilaria (Mf) prevalence was more than 1% and it was zero in all the sites in 2011. Transmission assessment survey (TAS), as per WHO guidelines- 2011 was conducted in 2013 for making a decision to stop or to continue MDA. The children in the age group of 6- 7 years were tested with ICT following the sample size derived from Survey Sample builder tool. Screening of 1696 children from 52 schools for filarial antigen using ICT showed that 16 children were positive for filarial antigen (0.9%) from eight sites. As the number of positive children is below the critical cut off (20), this evaluation unit (EU) is qualified for stopping further rounds of MDA. Investigations on the positive cases showed that all except two cases either migrated within 2- 3 years from neighbouring states or had the history of visiting filariasis endemic areas. All positive cases were treated with DEC @ 6mg/kg for 12 days. Operational issues related to the implementation of TAS are discussed in view of developing national guidelines in this article.