Lymphatic filariasis is a debilitating disease caused by parasitic worms transmitted through mosquito bites. In Nigeria, where lymphatic filariasis prevalence is high in rural areas, community-based handwashing promotion initiatives have been implemented to reduce infection rates. A cross-sectional survey was conducted with village populations, collecting data on handwashing frequency, knowledge about lymphatic filariasis, and infection status. Data were analysed using logistic regression to assess the impact of intervention factors. Handwashing frequency increased by 25% among villagers who received the promotion initiative compared to those in control villages (p < 0.01). There was a significant reduction in lymphatic filariasis infection rates by 30% (95% CI: -40%, -20%) after six months. Community-based handwashing promotion initiatives effectively reduced lymphatic filariasis infection rates and improved health awareness among Nigerian villagers, with statistically significant impact observed. Continued support for these initiatives is recommended to sustain the positive changes in hygiene practices and further reduce lymphatic filariasis prevalence in Nigeria. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.