From Burden to Breakthrough: The Impact of Mass Drug Campaigns on Microfilaria Trends Based on Evidence From Sentinel Site Surveillance in Rural Nagpur, Maharashtra, India, Over Two Decades.

Background Lymphatic filariasis (LF), often referred to as elephantiasis, is a neglected tropical disease that severely impacts health, causing chronic conditions such as lymphoedema and hydrocele. In India, it affects millions, leading to disability and social stigma, making elimination a priority. The National Vector Borne Disease Control Programme (NVBDCP) has been key in managing LF through mass drug administration (MDA), which traditionally used single-drug or two-drug regimens. The introduction of the triple-drug therapy in 2018, particularly in Nagpur, marks a shift to enhance effectiveness, aiming for faster transmission interruption. This study aims to assess the demographic and temporal distribution of LF and to evaluate the effectiveness of the triple-drug MDA in reducing key transmission indicators in Nagpur. Materials and methods This was a retrospective analysis of all eligible records (n = 36,080 individuals) available from the district LF sentinel-surveillance system between January 2004 and December 2024. Data were collected from four sentinel primary health centres (PHCs) (fixed spots): Titur, Bhiwapur, Gumthala, and Umred, covering the villages of Sili, Salebhatti, Bhowari, and Rajebabaward. From 2021, Takalghat and Borkhedi PHCs (villages: Turakmari and Ruikhiri) were added to monitor MDA coverage and microfilaria (MF) rates. The p-value of the MF rate in each year was calculated using a chi-square test analysis, which was performed with IBM SPSS Statistics for Windows, Version 24 (Released 2016; IBM Corp., Armonk, New York). Results A total of 36,080 individuals were surveyed, comprising 19,168 (53%) males and 16,912 (47%) females, with a female-to-male ratio of 0.88:1. The mean age of the study population was 30.67 ± 13.71 years (95% CI: 30.53-30.81 years), with a median age of 30.5 years. MF was detected in 441 individuals (1.22%), with a higher prevalence among males (285, 64.62%) compared to females (156, 35.37%). The highest MF positivity was recorded in the 6-15 age group, followed by the 16-25 age group, indicating greater vulnerability among younger individuals. Over the two-decade study period, MF cases declined substantially from 102 cases in 2004 to zero by 2022, demonstrating the sustained impact of MDA. Overall, the prevalence dropped from 4.91% in 2004 to 0% by 2024, reflecting the success of long-term filariasis elimination efforts in the Nagpur district. Conclusion The successful implementation of the triple-drug MDA strategy has significantly halted LF transmission in Nagpur, Maharashtra. This outcome highlights the effectiveness of the IDA (ivermectin, diethylcarbamazine, and albendazole) regimen when combined with strong public health efforts. To sustain elimination, continued community engagement and vigilant post-MDA surveillance are essential. The Nagpur experience serves as a model for other endemic regions aiming to achieve long-term control and eventual elimination of lymphatic filariasis.