Identifying Active Paragonimiasis in Rural Nagaland in Northeastern India- a Community-Based Cross-Sectional Study

Background Paragonimiasis is a neglected tropical disease (NTD) and of significant public health concern in northeastern India where it is frequently misdiagnosed as pulmonary tuberculosis. Transmission occurs through consumption of raw or undercooked freshwater crustaceans, a widespread dietary practice in this region. Accurate diagnosis will ensure cheap, effective treatment with praziquantel and avoid unnecessary prolonged tuberculosis therapy. This study determines the prevalence, specific risk factors for infection, and showcases a clinical scoring model to screen for active paragonimiasis in endemic areas. Methodology/Principal Findings A community-based cross-sectional survey was conducted in Medziphema block, Nagaland, in northeastern India screening 2,942 residents aged over 10 years. Participants reporting chronic cough ([≥]2 weeks) provided sputum and serum samples (93,3.16%). Sputum examination was screened for Paragonimus ova and acid-fast bacilli, and serum samples were tested for IgG antibodies against Paragonimus heterotremus using anti-Extra Secretory antigen by ELISA (positive case defined as titre [≥]0.5 IU). IgG-confirmed paragonimiasis was detected in 30 individuals, yielding a population prevalence of 1.02% (30/2942) and 32.3% (30/93) amongst symptomatic participants. Sputum microscopy demonstrated limited sensitivity (3.3%), detecting cysts in only one confirmed case. Tuberculosis co-infection was documented in 6.7% of sero-positive cases. Multivariable regression identified significant associations with increasing age (adjusted (aOR) 1.04) previous tuberculosis history (aOR 4.62), monthly snail consumption frequency (aOR 1.05), ever smoking (aOR 3.51), and education beyond middle school (aOR 2.93). Haemoptysis (aOR 9.86) was the strongest symptomatic predictor. Clinical scoring models were developed, with haemoptysis consistently emerging as the most robust predictor across all models. Conclusions/Significance Pulmonary paragonimiasis constitutes a prevalent yet under-recognised condition in several southeast-Asian communities, necessitating systematic screening as a differential diagnosis for pulmonary tuberculosis. The clinical scoring model facilitates early case identification in resource-constrained settings. Public health interventions must address dietary practices, particularly consumption of raw or undercooked freshwater crustaceans, to interrupt transmission.