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.

A cluster of parotitis cases (n = 13) were observed in a tribal population of Vansda village from the Union Territory of Dadra and Nagar Haveli, India between 20th and 22nd week of 2016. Primary information was received by the local Infectious Disease Surveillance Program team, and subsequently field investigations were carried out in the affected area. Active surveillance was conducted till twice the incubation period from onset of the last surveyed case. For the laboratory investigations, 19 serum samples were collected from 11-suspected cases and their close contacts (n = 8). All samples were transported within 12 h on icepacks to the main laboratory at Pune. Majority of the suspected mumps cases were children except four adults. Mumps infection was confirmed in 8 of 11 suspected cases with post-onset ranging from 28 to 43 days and none from the close contacts. Both mumps specific IgM and IgG antibodies were detected in nine cases (including one equivocal) and single contact (equivocal result). Overall, ten cases and eight contacts (including one equivocal) showed mumps specific IgG antibodies. Present investigation provides information about the characteristics of mumps outbreak in a tribal community that resides in the remote areas. In addition, introduction of mumps containing vaccine in the tribal population may have added advantages in the tribal health program.

During 9th December 2016 and 12th February 2017, 149-chickenpox cases were reported in a tribal and industrial zone of Rakholi (n = 80) and Surangi (n = 69) villages from Union Territory of India. An epidemiological investigation was performed to assess the characteristics and determinants of the chickenpox outbreak. Overall, the attack rate per 100 population in Rakholi village (n = 1757) was 4.5% and 19.1% in Surangi village (n = 360). Ages of the cases were ranged from 6 months to 55 years and there were 53 females and 96 males. For the laboratory investigations, 25 serum samples, three urine specimens, three throat swabs and six blister/skin swabs were collected from 37-suspected chickenpox cases. Altogether, 30-suspected cases were laboratory confirmed by either IgM EIA or varicella zoster virus (VZV) DNA PCR. Both VZV-specific IgM and IgG antibodies were detected in 19-suspected cases. Two suspected cases showed the presence of VZV-specific IgG antibodies but not IgM antibodies. On the contrary, three suspected cases showed VZV-specific IgM but not IgG antibodies. Overall, 31 of 37-suspected cases (including one equivocal case) were laboratory confirmed. The partial sequencing of ORF-28 gene of VZV revealed circulation of clade-1 viruses. In conclusion, this investigation provides detail information about the chickenpox outbreak in the tribal and industrial setting from India. Furthermore, the study emphasises the need to investigate more chickenpox outbreaks in different parts of India.

No abstract