Genomic investigation of an outbreak of febrile illness with rashes in the eastern Uttar Pradesh, India during March-May 2023

Various infectious diseases cause febrile illness with rash. Among these, measles and varicella zoster virus (VZV) infections are ubiquitous viral infections with classic symptoms of fever and rashes. During March-May 2023, an outbreak of fever with rashes was reported from five villages in the Gorakhpur district of Uttar Pradesh. Clinical specimens were collected from suspected patients (n = 42) and tested for Anti-measles IgM and Anti-VZV IgM. In addition to this, DNA from VZV-positive samples were amplified for ORF22, ORF38, ORF54, and glycoprotein B genes, to know the prevalent genotype. Of the total number of cases, thirty-three (78 %) cases were confirmed to be infected with VZV, detected either by PCR (27,81 %) or IgM ELISA (6,19 %), and five (11.9 %) co-infected cases were established through the presence of IgM antibodies for both (VZV and measles virus). Amplification of ORF38 and ORF54 genes of all VZV-infected patients were found to be positive for both the markers (BglI+ and PstI+). Further genetic analysis of ORF22 and glycoprotein B gene revealed clade 4/5 & clade 1/3 genotypes of VZV are responsible for the outbreak. These findings will be useful for future surveillance and formulation of policies to the immunization for VZV and measles.