Measles – Nepal

14 March 2023

Situation at a glance

On 2 January 2023, an outbreak of measles was confirmed in Nepalgunj sub-metropolitan city (SMC) in Banke district, Nepal, following a cluster of cases of fever and rash. Following the confirmation and through active case search, the index case was identified, with the onset of symptoms on 24 November 2022. Between 24 November 2022 and 10 March 2023, 690 measles cases, including one associated death (case fatality ratio: 0.14 %), have been reported from seven districts in western Nepal, and three districts in eastern Nepal (mainly in the Terai ecological region). The majority of the cases (n=591; 86%) have been reported in children aged less than 15 years.

While measles is endemic in Nepal and is reported every year, the magnitude and extent of the current outbreak are unusually high compared to the previous years. Only sporadic isolated measles cases have occurred since 2004, when a substantial outbreak of over 12 000 cases was reported. The risk of spread of measles is assessed as high at the national level and moderate at regional level, due to the spread of the outbreak from Nepalgunj SMC to other districts and provinces, the detection of measles cases in a highly mobile population with frequent cross-border travel, and low population immunity of the affected districts. Response measures in affected areas have been implemented, including active case search, case management and outbreak response immunization (ORI).

Description of the situation

Between 24 November 2022 and 10 March 2023, a total of 690 measles cases, including one associated death (CFR 0.14%) have been reported from seven districts in western Nepal (Banke – 327 cases; Surkhet– 62 cases; Bardiya – 49 cases; Kailali – 39 cases; Kanchanpur – 27 cases; Bajura – 13 cases, and Dang – 12 cases), and three districts in eastern Nepal (Mahottari – 103 cases; Sunsari – 34 cases; and Morang – 24 cases) .

The outbreak started in western Nepal 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 NPHL has also detected laboratory-confirmed measles cases in eastern Nepal. The dates of the onset of the outbreaks in Mahottari, Morang, and Sunsari districts were reported as 24 December 2022, 23 December 2022, and 16 January 2023, respectively. These measles outbreaks are ongoing and adequate ORI must be undertaken to prevent spread of these outbreaks to adjoining districts .

The present outbreak is occurring in two clusters of districts in the southern part of Nepal bordering India (Figure 2). 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.

Figure-1: Number of measles cases (n=690) reported in Nepal between 24 November 2022 to 10 March 2023

As shown in Figure-1, the number of cases increased sharply in the last week of December but started declining in the second week of January and continues to show a declining trend.

Figure 2: Distribution of measles cases (n= 690) reported by district in Nepal between 24 November 2022 to 10 March 2023

Most of the cases (n=327; 47%) were reported from Banke district, Lumbini province, which borders India. Additionally, the routine immunization outreach session sites and microplan¹ 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.

The majority of cases (n=591; 86%) have been less than 15 years old. However, nine measles cases have also been observed in the older age group (≥ 45 years) with the maximum age of a case being 73 years.

The current outbreak occurs in a population with suboptimal population immunity, which is partly due to the disruption in routine immunization services during the COVID-19 pandemic, as well as the quality of nationwide measles-rubella (MR) supplementary immunization activities conducted in 2020. Over half of the cases (58%;n=400) are unvaccinated, of these 68% (n=272) 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 MR, 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.

Figure 3: Age distribution and vaccination status of measles cases in Nepal from 24 November 2022 to 10 March 2023

Epidemiology of measles

Measles is a highly contagious disease caused by the measles virus. Transmission is primarily person-to-person by airborne respiratory droplets that disperse within minutes when an infected person coughs or sneezes. Transmission can also occur through direct contact with infected secretions. Transmission from asymptomatic exposed immune persons has not been demonstrated. The virus remains active and contagious in the air or on infected surfaces for up to two hours. A patient is infectious four days before the start of the rash to four days after its appearance. The virus first infects the respiratory tract before spreading to other organs. There is no specific antiviral treatment for measles and most people recover within 2-3 weeks.

Among young and malnourished children and immunocompromised people, including those with HIV, cancer or treated with immunosuppressives, as well as pregnant women, measles can cause serious complications, including blindness, encephalitis, severe diarrhea, ear infection, pneumonia, and death.

An effective and safe vaccine is available for prevention and control. The measles-containing vaccine first dose (MCV1) is given at the age of nine months, while the second dose of the measles-containing second dose (MCV2) is given at the age of 15 months. A 95% population coverage of MCV1 and MCV2 is required to stop measles circulation.

In areas with low vaccination coverage, epidemics typically occur every two to three years and usually last between two and three months, although their duration varies according to population size, crowding, and the population’s immunity status.

Public health response

The Ministry of Health (MoH), with support from WHO, partners and non-governmental organizations (NGOs), have implemented response measures. These include:

Ongoing active case search and line listing of fever and rash cases. Vitamin A is administered to those identified with fever and rash.
The mobilization of health personnel including health care workers (HCW), local NGOs, and technical staff from WHO, UNICEF, the District Public Health Office, and the health unit of Nepalgunj SMC to implement response measures.
The launch of non-selective ORI on 6 January 2023 by Nepalgunj SMC, targeting children aged six months to 15 years. As of 6 February, a total of 153 485 children have been vaccinated with one dose of the measles-rubella (MR) vaccine. ORI is being conducted in Nepalgunj SMC (with a target of 100% coverage) and adjoining municipalities (including Khajura, Narainapur, Duduwa, Janki, Raptisenari, Baijanath, and Kohalpur).
Ongoing non-selective ORI with the MR vaccine in Banke and Kailali districts for children aged between six months and 15 years. The government plans to expand this ORI response to other affected/high-risk districts of western Nepal.
Strengthening measles surveillance and mobilization of the district rapid response team (RRT) in Banke district.
Ensuring an adequate stock of vaccines and logistics, as well as medicines for supportive treatment, are available at the provincial and federal governments in case of urgent need.

WHO risk assessment

The outbreak initially reported in Nepalgunj SMC in Lumbini province has expanded, and cases are being reported in adjoining municipalities and provinces in western Nepal, and also eastern Nepal.
The number of cases might be higher than reported, as cases in communities are not always counted due to suboptimal surveillance activities and underreporting of identified cases.
The presence of a large number of migrants and mobile populations, making them vulnerable to measles infection:a significant number of the migrant population may not have information or access to routine immunization sites and are likely to miss routine immunization.
The outbreak occurring in an area with a porous border between India and Nepal.
Low vaccination coverage due to COVID-19 pandemic-related disruptions, which have led to an immunity gap in the population. The independent coverage survey post-measles rubella (MR) vaccination campaign in Nepal in 2020 (undertaken during the COVID-19 pandemic) shows 84% national coverage, indicating a high number of children vulnerable to measles infection.

Factors including the spread of the outbreak to neighboring districts and provinces, the detection of measles cases in a highly mobile population and minority communities, the low population immunity in affected districts, and cross-border movement, indicates the risk of intra- and inter-provincial as well as international spread of measles.

The risk at regional level is assessed to be moderate (persistent endemic transmission on both sides of a porous international border), and low at the global level.

WHO advice

Measles is preventable by vaccination, which provides lifelong immunity in most recipients. Vaccination against measles is recommended for all susceptible children and adults for whom the vaccine is not contraindicated. National immunization programs must assure the safe provision of immunization services that can reach all children with two doses of measles vaccine. In countries with moderate to weak health systems, regular measles immunization campaigns can protect children who do not have access to routine health services. WHO recommends maintaining sustained homogeneous coverage of at least 95% with the first and second doses of the MCV vaccine and strengthening integrated epidemiological surveillance of measles and rubella in order to achieve the timely detection of all suspected cases in public, private, and social security healthcare facilities.

It is critical to quickly recognize and treat complications of measles in order to reduce severity of the disease and mortality . Severe complications from measles can be reduced through supportive care that ensures good nutrition, adequate fluid intake and treatment of dehydration with WHO-recommended oral rehydration solution. This solution replaces fluids and other essential elements that are lost through diarrhea or vomiting. Antibiotics should be prescribed to treat eye and ear infections, and pneumonia. While there is no specific antiviral treatment for measles, prompt provision of vitamin A in therapeutic doses is recommended to reduce complications and mortality among infected children.

Healthcare workers should be vaccinated in order to avoid infections acquired in a healthcare setting.

WHO does not recommend any travel and/or trade restrictions to Nepal based on the information available for this event.

Further information

WHO Measles factsheet: https://www.who.int/news-room/fact-sheets/detail/measles
WHO Immunization dashboard: https://immunizationdata.who.int/

¹Microplanning for immunization service delivery using the Reaching Every District (RED) strategy: https://apps.who.int/iris/handle/10665/70450

Citable reference: World Health Organization (14 March 2023). Disease Outbreak News; Measles – Nepal. Available at https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON446