Outbreak of mumps virus genotype G infection in tribal individuals during 2016–17 in India

Abstract

Tribal individuals presented with fever and uni- or bi-lateral parotitis in Galonda and Silli villages (Dadra and Nagar Haveli, India) between 2 October 2016 and 19 March 2017. Consequently, the magnitude and epidemiological characteristics of the outbreak were investigated. Overall, 139 cases of suspected mumps were identified in both the above villages. Most of the suspected cases were 5-15 years old, the exceptions being three adults who had no noticeable complications. Specimens were collected from 42 of the suspected cases and their close contacts (n = 39) for laboratory investigation. Mumps infection was laboratory-confirmed in 73.8% and 20.5% of the suspected cases and contacts, respectively. Mumps was confirmed in seven adults aged 17-42 years, including three suspected cases and four contacts. To the best of our knowledge, this is the first report of a complete virus genome circulating among tribal individuals. Sequencing and phylogenetic studies revealed circulation of mumps virus genotype G in these tribal villages with 99% identity to a mumps virus detected in the UK (1996) and Canada (2009). Comparison with Indian mumps viruses revealed 99% and 98% identity to previously reported isolates from Pune during 2012 and 1986, respectively. Although the outbreak was large, no major complications were reported in the tribal villages. Detection of asymptomatic mumps in numerous close contacts indicates the importance of laboratory investigations in an outbreak setting.

Mumps outbreak investigation in Jaisalmer, Rajasthan, India, June‐September 2016

“…However, the outbreak was limited to five villages; their location in the Thar desert of Jaisalmer with large distances between villages likely played a role in limiting the geographic spread of the outbreak. This outbreak affected a considerable proportion of adults, which is typical in a population that is unimmunized . Low prevalence of complications is similar to what has been reported in other studies and investigations …”

“…[7][8][9][10][11][12] Low prevalence of complications is similar to what has been reported in other studies and investigations. 9,10,12 The overall attack rate (2%) was lower compared with other outbreaks 12 probably due to following prompt actions by school staff: detection of symptoms, arranging consultation by a medical officer, allowing absence from school, and requesting children to report similar illness among family members to school staff or medical officer. These practices in a unvaccinated population limited the spread and associated complications, however, the epidemic took its natural course and ended.…”

“…The epidemiology of this outbreak is similar to that of recent outbreaks reported in tribal villages of neighboring Dadra and Nagar Haveli, Maharashtra, and Karnataka. 7,[9][10][11][12] Our investigation had limitations. 13 ; as we did not test for any of these infections, it is possible that there are false positives in our investigation.…”

“…These practices in a unvaccinated population limited the spread and associated complications, however, the epidemic took its natural course and ended. The epidemiology of this outbreak is similar to that of recent outbreaks reported in tribal villages of neighboring Dadra and Nagar Haveli, Maharashtra, and Karnataka …”

“…India may want to consider mumps as a notifiable disease and include it in routine surveillance under IDSP to estimate disease burden . This recommendation is consistent with the recommendations of other researchers in India . More outbreaks need to be investigated to understand the epidemiology of mumps in India and to guide future vaccination policy.…”