Lymphatic filariasis (LF) was first recorded in India as early as the sixth century BC. Since then, India has consistently worked toward building its knowledge on the cause, symptoms, and treatment of the disease. According to data from 2018, India bears 50 percent of the global LF burden and records an at-risk population of 650 million spread across 21 states and union territories. , ,
Over the years, India has implemented many programs that have contributed to its steady progress toward eliminating LF.6 India began its LF interventions in 1949, with a pilot project in Odisha that aimed to control LF through single-drug therapy, along with antilarval and adult mosquito management measures. This pilot paved the way for the National Filaria Control Programme––the first national program aimed at tackling LF. The program had limited success due to community noncooperation and ineffectiveness of the indoor insecticidal spray. Nonetheless, lessons from the program were integral to the development and rollout of the multipronged Elimination of Lymphatic Filariasis (ELF) program in 2004. The national program for ELF is based on a twin pillar strategy of chemotherapy via mass drug administration (MDA) and morbidity management and disability prevention for alleviation of chronic illness. The objective of the program is to cover all eligible populations living in endemic districts through annual MDA campaigns to reduce the infection level in the community below a threshold at which the spread of the infection can no longer be sustained and transmission stops.
The World Health Organization recommends using transmission assessment surveys to determine when the rate of microfilaria infection has been reduced below the threshold level of 1 percent and MDA can stop. Once MDA has stopped, continued surveillance is conducted, through transmission assessment surveys, to assess the infection levels within the community. An implementation unit, usually an endemic district, is the smallest administrative unit used as the basis for deciding to implement MDA. Implementation units conduct transmission assessment surveys after at least five rounds of MDA that met the critical criterion of coverage of more than 65 percent of the population. The survey is administered three times, every two years, to confirm the microfilaria rates in the population remain below the threshold value. When the implementation unit has successfully cleared transmission assessment surveys 1, 2, and 3, it is considered free of LF.
Figure 1. Endemic population vs. TAS cleared districts
Since the launch of the ELF program in 2004, 143 endemic districts in India have started implementing MDA annually. Many states have demonstrated progress in reducing their LF burden since the ELF program began; Odisha’s case has emerged as noteworthy. Odisha’s microfilarial rate at the beginning of the ELF program in 2004 was 2.6 and had dropped to 0.68 in 2015. Its radical progress in eliminating LF is the reason why it has been selected as an exemplar state to be studied by the Exemplars program
Figure 2. Endemic States in India in 2004
Other Indian states with large endemic populations such as Kerala, Tamil Nadu, and Andhra Pradesh also made significant progress in clearing the transmission assessment surveys (Figure 1). However, Odisha bore a close resemblance with other large states that are lagging behind in the elimination of LF—such as Bihar, Madhya Pradesh, Jharkhand, Uttar Pradesh, and Chhattisgarh––on indicators including child mortality, literacy, immunization of children, anemia among women, and state domestic product per capita (Figure 3). Lessons from Odisha’s ELF program are therefore particularly relevant for these states.
Figure 3: Health and socioeconomic factors in Odisha compared with other high-burden states
Data from: National Family Health Survey ; Census 2011 ; Reserve Bank of India (2014) ; and Maharashtra Economic Survey 2019-20 .
Within Odisha State, more than 50 percent of the districts under post-MDA assessment have cleared transmission assessment surveys 2 or 3, including Boudh, Gajapati, Jajpur, Kendrapara, Koraput, Malkangiri, Navrangpura, and Pur (Figure 4), according to data provided by the National Vector Borne Disease Control Programme. For this research study, we selected Koraput, Kendrapara, and Jajpur for closer analysis. Koraput and Kendrapara were selected despite having an initially low microfilarial rate because of the unique challenges they present as remote tribal districts. Both districts conducted 9 rounds of MDA to clear transmission assessment survey 3 by 2019. Jajpur conducted 11 rounds of MDA to clear transmission assessment survey 2 by 2019.
Figure 4: Status of transmission assessment surveys in Odisha
Odisha’s experience offers relevant lessons to inform decision making across other states to enable savings in cost, time, and effort. States that are currently implementing MDA and facing challenges with lack of awareness can draw lessons from Odisha’s rigorous information, education, and communications activities and multichannel social mobilization strategies. In case of resource constraints, states can leverage Odisha’s partnership approach to bring in community-based organizations to reduce time, cost, and effort. Lastly, states that are focused on improving the knowledge and skill of their staff members can use the learnings from Odisha’s targeted training and capacity-strengthening efforts to customize and improve training outcomes.