An outbreak of measles has been confirmed in Nepalgunj sub-metropolitan city (SMC) in Banke district, Nepal, with the onset of symptoms on 24 November 2022. Between 24 November 2022 and 10 March 2023, 690 measles cases, including one associated death, have been reported from seven districts in western Nepal and three districts in eastern Nepal. The majority of cases, 86%, have been reported in children aged less than 15 years.

The outbreak is considered unusually high compared to previous years and the risk of spread of measles is assessed as high at the national level and moderate at the regional level. The response measures implemented in affected areas include active case search, case management and outbreak response immunization (ORI).

The outbreak started in Nepalgunj SMC, Banke district, Lumbini province, after a cluster of fever and rash cases was reported on 29 December 2022. Measles was confirmed by the National Public Health Laboratory (NPHL) on 2 January 2023. Following the confirmation and active case search in Nepalgunj SMC and adjoining municipalities, the first measles case was retrospectively identified from Nepalgunj SMC with a symptom onset of 24 November 2022.

The present outbreak is occurring in two clusters of districts in the southern part of Nepal bordering India. Due to the porous international border, and measles being endemic in both Nepal and India, the country’s source of infection cannot be determined definitively without further molecular epidemiological studies.

The majority of cases were reported from Banke district, Lumbini province, which borders India. Additionally, the routine immunization outreach session sites and microplan were not developed with community involvement, leading to very few outreach session sites, a lack of awareness, and a large number of children who missed the vaccination.

Over half of the cases, 58%, are unvaccinated, and of these, 68% were less than four years of age. Only 31% and 28% of cases in age groups 1-4 years and 5-9 years, respectively, have received two or more doses of measles-rubella (MR) vaccine, showing susceptibility in these cohorts. According to the WHO/UNICEF estimates of national immunization coverage, in Nepal, the measles-containing vaccine first dose (MCV1) and second dose (MCV2) coverage were reported to be 90% and 87% respectively in 2021 nationally.

The outbreak is ongoing and adequate ORI must be undertaken to prevent its spread to adjoining districts. The response measures implemented include active case search, case management, and outbreak response immunization (ORI).