DYNAMICS OF HOUSEHOLD CONTACT TRANSMISSION OF TUBERCULOSIS DURING FESTIVAL SEASONS

Abstract

Tuberculosis (TB) continues to be a significant public health problem in Nigeria, with household transmission accounting for much of the current TB burden. Cultural and religious festivals like Eid and Christmas are associated with increased social interaction, intergenerational visits, communal meals and indoor crowding, yet its impact on household TB transmission has not been systematically investigated. Using data from three Nigerian states (Lagos, Kano and Kaduna), this prospective observational study sought to establish whether household TB incidence was significantly increased during festival periods. We followed 450 households (2,180 contacts of index pulmonary TB cases) before and after festival periods. Structured household surveys obtained information about social behaviour, household composition, crowding and ventilation practice. Symptomatic contacts were screened by sputum microscopy and GeneXpert, while asymptomatic contacts underwent interferon-gamma release assays. To confirm potential household transmission clusters, molecular epidemiological analyses were performed using spoligotyping and MIRU-VNTR analysis. After the festival, 58 new TB cases were diagnosed compared to 19 before the festival with a significant increase in household incidence (p < 0.001). Those under 15 years and from dense households are the worst-hit. Molecular analyses identified genetic linkage between index cases and 72% of post-festival cases, providing evidence consistent with intra-household transmission. However, temporal linkage with festival exposure requires cautious interpretation because tuberculosis transmission and progression may extend beyond the immediate observation period. The main predictors of post-festival transmission were: being in a crowded household, staying overnight and poor ventilation. Our results show that social behaviour during the festival was a major facilitator of TB transmission in Nigerian households. This study underlines the importance of focused pre- and post-festival screening, improved contact tracing, behavioral and environmental interventions, as well as culturally appropriate public health education in minimizing festival-associated TB transmission.