An outbreak of influenza B in an isolated nomadic community in Jammu & Kashmir, India

BACKGROUND & OBJECTIVES: Community outbreaks of disease amongst nomadic populations generally remain undocumented. Following a reported increase in acute respiratory tract infections (ARI) in May 2011 in a nomadic population of Sangerwini in Jammu & Kashmir, India, we examined the patients with ARI symptoms and their nasal swabs were tested for influenza virus. METHODS: Patients with ARI (n=526) were screened from May 14 to 23, 2011 and nasopharyngeal swabs collected from 84 with Influenza like illness (ILI) for bacterial cultures and influenza virus testing. Samples were tested for influenza A and influenza B by real time (RT)-PCR. RESULTS: Twelve (14.3%) of the 84 patients tested positive for influenza B, compared to only one (0.9%) of 108 patients with ILI in a parallel survey performed in Srinagar during the same period, suggesting a localized outbreak in the isolated nomadic community. All presented with respiratory symptoms of less than seven days. Familial clustering was seen in 40 per cent (25% of influenza B positives). Average daytime temperatures ranged from 15-16°C compared to 22°C in Srinagar. Four patients developed pneumonia whereas others ran a mild course with a total recovery with oseltamivir and symptomatic therapy. INTERPRETATION & CONCLUSION: Our report of confirmed influenza B in this underprivileged nomadic population argues for routine surveillance with efforts to improve vaccination and infection control practices.