Sunday, 17 November 2024

Global number of Measles cases rose by 20% in 2023.

The number of Measles cases recorded worldwide rose by 20% in 2023 (compared to 2022), with 10.3 million cases recorded globally, according so a joint press release issued by the World Health Organization and the U.S. Centers for Disease Control and Prevention. The main driver of this rise in cases is thought to be inadequate immunization coverage.

Two doses of Measles vaccine is sufficient to protect against infection with the disease, but 17% of children who should have received their first dose of the vaccine in 2023 are thought not to have done so (more than 22 million children), while 26% of children who should have received a second dose in 2023 did not do so. A vaccine coverage rate of 95% or higher for both vaccine doses is thought to be needed to prevent Measles spreading within a population.

Fifty seven countries are thought to have suffered Measles outbreaks due to gaps in vaccination coverage, a 60% rise on the 36 countries which suffered such outbreaks in 2022. The World Health Organization's African, Eastern Mediterranean, European, South-East Asia and Western Pacific regions were affected, with over half of outbreaks occurring in the African Region. Only the Americas Region was not affected by a Measles outbreak in 2023.

A doctor examines a girl with measles at the Republican Infectious Diseases Clinical Hospital, Bishkek city, Kyrgyzstan. Danil Usmanov/World Health Organization.

'Measles vaccine has saved more lives than any other vaccine in the past 50 years,' according to Tedros Adhanom Ghebreyesus, the Director General of the World Health Organization. 'To save even more lives and stop this deadly virus from harming the most vulnerable, we must invest in immunization for every person, no matter where they live.'

Measles is a human disease caused by a Virus in the Paramyxovirus family. The Virus infects the respiratory tract, then spreads throughout the body. 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.

Thin-section transmission electron micrograph revealing the ultrastructural appearance of a single Viron, of the Measles Virus. The measles Virus is a Paramyxovirus, of the genus Morbillivirus. It is 100-200 nm in diameter, with a core of single-stranded RNA, and is closely related to the Rinderpest and Canine Distemper Viruses. Two membrane envelope proteins are important in pathogenesis. They are the F (fusion) protein, which is responsible for fusion of virus and host cell membranes, viral penetration, and hemolysis, and the H (hemagglutinin) protein, which is responsible for adsorption of virus to cells. Centers for Disease Control and Prevention/Wikimedia Commons.

It is estimated that 107 500 people died of Measles in 2023, most of them children below the age of five. This is an eight 8% drop in fatalities compared to 2022. The reason for this lower fatality rate in 2023, despite a higher infection rate, is thought to be that more cases of Measles were reported in 2023 in countries with generally better healthcare and childhood nutrition rates, where infected children are less likely to die. However, this is not all good news, as even where Measles is not fatal, it can cause a number of severe health problems, including blindness, pneumonia, and encephalitis (swelling of the brain, often leading to brain damage).

Measles is one of twenty life-threatening diseases which it was hoped could be eliminated through vaccination campaigns by 2030 under the remit of the Immunization Agenda 2030 program. In the first week of November 2024, Brazil was declared to be Measles-free, meaning that the disease had been eliminated in the Americas Region, and at least one nation in each of the other regions, with the exception of Africa, also having Measles-free status. However, the decline in vaccine-uptake, and the subsequent rise in Measles cases around the world, means that this project is now threatened.

The African and Eastern Mediterranean regions are thought to be in particular need of urgent and targeted interventions to ensure vaccine availability and uptake, particularly in conflict-affected and other vulnerable settings. Greater surveillance for cases is also needed in all regions, in order to facilitate prompt responses to outbreaks when they occur.

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