Measles - South Africa - World Health Organization

Situation at a glance

Sporadic cases of measles were reported in South Africa throughout 2022. In epidemiological week 40 in 2022 (ending 8 October 2022) an outbreak was declared in Limpopo province. As of 16 March 2023, confirmed cases have been reported from all provinces; eight out of nine South African provinces have declared measles outbreaks¹. No deaths associated with measles have been recorded. Most cases (86%) are reported among those aged under 14 years.

Community-based surveillance has been strengthened and the Ministry of Health (MoH) is conducting a mass measles vaccination campaign targeting children aged between 6 months and 15 years in all provinces.

WHO assesses the risk posed by the current outbreak as high at the national level, moderate at the regional level and low at the global level.

Description of the situation

South Africa is a measles-endemic country, with several measles outbreaks reported in recent years.

Sporadic cases were reported in all nine provinces in South Africa in 2022. As of 4 March 2023, measles outbreaks were declared in eight provinces, further to the outbreak which was declared in Limpopo province in October 2022 (Figure 1).

Figure 1: Epidemiological curve of laboratory-confirmed measles cases in South Africa from week 40, 2022 to week 10, 2023 Source: NICD South African Measles Outbreak 2023 Update 16 March

From epidemiological week 40, 2022 (ending 8 October 2022) to week 10, 2023 (ending 4 March 2023), the National Institute of Communicable Diseases (NICD) tested 4830 serum samples for measles, of which 772 (16%) were confirmed measles cases (Figure 2).

Figure 2: Number of serum samples tested by NICD and positivity rate (%) in South Africa, week 40 of 2022 to week 10 of 2023

The 772 laboratory-confirmed measles cases were reported from the provinces of: Limpopo (275; 36%), North West (198; 26%), Gauteng (124; 16%), Mpumalanga (106; 14%), Free State (28; 3.5%), KwaZulu-Natal (17; 2%), Western Cape (11; 1.5%), Northern Cape (7; 1%) and Eastern Cape (6; 1%) (Figure 3).

Figure 3: Geographical distribution of laboratory-confirmed measles cases in South Africa, week 40 of 2022 (ending 8 October 2022) to week 10 of 2023 (ending 4 March 2023)

The age of laboratory-confirmed measles cases ranges from two months to 60 years. The majority of cases (42%) are in the age group 5-9 years, followed by the age groups 1-4 years (25%) and 10-14 years (19%). The attack rates (per 100 000 population) are highest among age groups 1-4 years (4.7 / 100 000) and 5-9 years (6.6 / 100 000).

Out of the laboratory-confirmed cases, 80 (10%) were vaccinated with at least one dose of measles-containing vaccine (MCV), 92 (12%) were unvaccinated, and the vaccination status of 570 (79.1%) is unknown.

According to the South African National Department of Health (NDOH), national immunization coverage of the measles-containing vaccine first dose (MCV1) and second dose (MCV2) was estimated at 87% and 82% respectively in 2021, while in 2022 the respective coverage was 86% and 86%. However, historical vaccination coverage has been low, which may be contributing to the current resurgence. According to WHO-UNICEF estimates, in 2018, MCV1 coverage averaged 81% and MCV2 75%. In 2017, MCV1 and MCV2 coverage was estimated at 81% and 78%.

 

Epidemiology of measles

Measles is caused by a virus in the paramyxovirus family. The virus infects the respiratory tract, then spreads throughout the body. Measles is a human disease and is not known to occur in animals. It can lead to major epidemics with significant morbidity and mortality, especially among vulnerable people. Among young and malnourished children, pregnant women and immunocompromised individuals, including those with HIV, cancer or treated with immunosuppressives, measles can cause serious complications, including ear infection, severe diarrhea, blindness, encephalitis, pneumonia, and death.

Transmission is primarily person-to-person by airborne respiratory droplets that disperse rapidly 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 from four days before the start of the rash to four days after its appearance. There is no specific antiviral treatment for measles and most people recover within 2-3 weeks.

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.

South Africa has had several outbreaks in recent years. Between 2003 and 2005, an outbreak occurred with 1676 cases reported. In 2009-2010, a large outbreak occurred with 18 431 documented cases. In 2017, a small outbreak was declared in Western Cape, Gauteng, and Kwazulu-Natal provinces, with a total of 186 cases. In 2019, a cluster of measles cases was reported in Cape Town affecting four siblings with a travel history to a measles-affected country.

Although measles is highly contagious, an effective and safe vaccine is available for prevention and control. MCV1 is given at the age of 9 months in countries with both ongoing transmission and a high risk of measles mortality among infants. These countries should administer the routine MCV2 at the age of 15-18 months. However, in South Africa, MCV1 is given at 6 months and MCV2 is given at 12 months³. A 95% population coverage of MCV1 and MCV2 is required to stop measles circulation. Reaching all children with two doses of the measles vaccine is recommended to ensure immunity and prevent outbreaks, as about 15% of vaccinated children fail to develop immunity from the first dose.

Routine vaccination of children against measles, combined with mass immunization campaigns in countries with high morbidity and mortality rates, are key public health strategies to reduce burden and transmission.

There is no specific treatment for measles. Case management of measles focuses on supportive care as well as the prevention and treatment of measles complications and secondary infections. Since measles is highly contagious, patient isolation is an important intervention to prevent the further spread of the virus.

Oral rehydration salts should be used as needed to prevent dehydration. All children diagnosed with measles should receive two doses of vitamin A oral supplements, given 24 hours apart, irrespective of the timing of previous doses of vitamin A; 50 000 international units (IU) should be given to infants aged < 6 months, 100 000 IU to infants aged 6-11 months and 200 000 IU to children aged 12 months. This treatment restores low vitamin A levels in acute measles cases that occur even in well-nourished children, and can help prevent eye damage and blindness. Vitamin A supplements have also been shown to reduce the number of measles deaths.

Nutritional support is recommended to reduce the risk of malnutrition due to diarrhoea, vomiting and poor appetite associated with measles. Breastfeeding should be encouraged where appropriate.

In unimmunized or insufficiently immunized individuals, the measles vaccine may be administered within 72 hours of exposure to the measles virus to protect against disease. If the disease does subsequently develop, symptoms are usually less severe, and the duration of illness may be shortened.

WHO does not recommend any restrictions on travel or trade to or from South Africa.