Circulation of two mumps virus genotypes in an unimmunized population in India.

Two separate outbreaks of fever with parotitis were reported from the Apsinga and Pimpla villages in the Osmanabad district of the Maharashtra State, India during February and March 2012. Meningo-encephalitis was noted in two patients resulting in the death of an 11-year male. Samples of blood and throat swabs were collected from patients with fever and parotitis. Serum samples from suspected (n=62) and convalescent (n=19) patients were tested for mumps virus specific IgM and/or IgG antibodies. Mumps virus specific IgM antibodies were detected in 44 of 62 serum samples (71%). Of the 19 convalescent phase sera 16 had both, anti-mumps virus IgM and IgG antibodies. Twenty-eight throat swabs collected from patients with parotitis were tested by RT-PCR for the SH gene. Twenty-three specimens were found to be positive and nucleotide sequencing of the amplified PCR products revealed circulation of two distinct genotypes that were village specific. Mumps virus genotype C (n=18) was detected in Apsinga village and genotype G (n=5) in Pimpla village. Two mumps virus isolates were also obtained using Vero cells. This is the first report from India confirming simultaneous circulation of mumps virus genotype C in one village and the G genotype in another village only 37 km away.