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

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.

Utility of neutralization test for laboratory diagnosis of suspected mumps.

Mumps is an infectious disease caused by mumps virus (MuV), which belongs to the family Paramyxoviridae and genus Rubulavirus. Typical symptoms of mumps include fever and swelling of the parotid glands; however, mumps can be asymptomatic. Mumps is diagnosed by molecular and serological methods (i.e., PCR and Enzyme Immunoassay [EIA]); however, both methods have pros and cons. This study was performed to compare the diagnostic utility of a focus reduction neutralization test (FRNT) to that of MuV-specific commercial IgM and IgG antibody EIA in patients suspected of having mumps. One hundred-eighty six samples collected during mumps outbreak in 2012-16 were studied. Samples (n = 80) were tested by all the three serological assays and showed 70.4%, 83% and 92.5% positivity by IgM EIA, IgG and FRNT, respectively. In all, 58.8% samples (n = 47) tested positive in all three assays. Concordance between mumps RT-PCR and IgM EIA was highest during the first 2-5 days and decreased with increasing time post-onset. Mumps FRNT results agreed with those of RT-PCR/IgM EIA from the second week onwards, whereas the results of mumps IgG EIA agreed with those of RT-PCR/IgM EIA from post-onset days 3-10. These findings suggest the utility of a FRNT for laboratory diagnosis of mumps in countries whose populations are not immunized against this infection.

Mumps outbreak in a tribal population from the Union Territory of Dadra and Nagar Haveli, India.

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.

Complete Genome Sequence of Mumps Virus Isolated from Karnataka State, India.

We report the first whole-genome sequence of mumps virus isolated from a two-year-old girl with bilateral parotitis from a Chikkahallivana village in the Davangere district of Karnataka State, India. The genome of the Davangere mumps isolate was 15,384 bp in length and identical to previously published mumps virus (MuV) genomes from India. BLAST results show 99.1% identity with previously sequenced genotype C viruses isolated from the states of Maharashtra, Tamil Nadu, and Uttar Pradesh.

Complete genome sequence of mumps viruses isolated from patients with parotitis, pancreatitis and encephalitis in India.

Limited information is available regarding epidemiology of mumps in India. Mumps vaccine is not included in the Universal Immunization Program of India. The complete genome sequences of Indian mumps virus (MuV) isolates are not available, hence this study was performed. Five isolates from bilateral parotitis and pancreatitis patients from Maharashtra, a MuV isolate from unilateral parotitis patient from Tamil Nadu, and a MuV isolate from encephalitis patient from Uttar Pradesh were genotyped by the standard protocol of the World Health Organization and subsequently complete genomes were sequenced. Indian MuV genomes were compared with published MuV genomes, including reference genotypes and eight vaccine strains for the genetic differences. The SH gene analysis revealed that five MuV isolates belonged to genotype C and two belonged to genotype G strains. The percent nucleotide divergence (PND) was 1.1% amongst five MuV genotype C strains and 2.2% amongst two MuV genotype G strains. A comparison with widely used mumps Jeryl Lynn vaccine strain revealed that Indian mumps isolates had 54, 54, 53, 49, 49, 38, and 49 amino acid substitutions in Chennai-2012, Kushinagar-2013, Pune-2008, Osmanabad-2012a, Osmanabad-2012b, Pune-1986 and Pune-2012, respectively. This study reports the complete genome sequences of Indian MuV strains obtained in years 1986, 2008, 2012 and 2013 that may be useful for further studies in India and globally.