"The disruption in recent months has led to a pool of unvaccinated children building up across West Africa—leaving them susceptible to measles and opening the door to a large increase in cases," says Andy Tatem. (Credit: UNICEF Guinea/Flickr)

Africa

How Ebola crisis could cause measles to spike

There could be 100,000 more cases of measles across the three countries most affected by the Ebola outbreak in West Africa, a new study reports.

The findings warn that the size of a measles outbreak could increase from 127,000 cases reported at the start of the Ebola epidemic in early 2014, to 227,000 after 18 months of the outbreak, resulting in an additional 5,000 measles deaths, and potentially as many as 16,000—or double the number of reported Ebola deaths.

Both increases would be due to an interruption in childhood immunization programs in Guinea, Liberia, and Sierra Leone, due to huge demands placed on the countries’ healthcare systems.

gif map shows rate of measles
(Credit: U. Southampton)

Disruption in health services

For the study, published in the journal Science, researchers used sophisticated modeling techniques to project the likely spread of measles—taking into account factors such as birth rates, infection susceptibility, and population rates.

High-resolution map data shows detailed information on population distribution and age structures. The data is derived from official national statistics, household surveys, birth rates, satellite imagery, and other sources.

“The Ebola epidemic is one of the worst public health crises in recent memory causing tens of thousands of people to become critically ill and thousands more to die,” says Andy Tatem, a geographer at University of Southampton.

“It has also caused severe disruption to health care services in the affected countries, including childhood vaccination programs—thus creating a second public health risk.

“The disruption in recent months has led to a pool of unvaccinated children building up across West Africa—leaving them susceptible to measles and opening the door to a large increase in cases.”

1.1 million unvaccinated children

Overall, it is estimated measles immunization in West Africa has fallen by 75 percent because of Ebola. Using this figure, researchers predicted that after 18 months of healthcare disruption 1,129,376 children aged between 9 months and 5 years will be left unvaccinated—compared with 778,000 prior to the crisis.

“Our study shows it is crucial to have an aggressive regional vaccination program ready to run, as soon as the threat of Ebola begins to recede, to help counter the steep downturn in immunization rates,” Tatem says.

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“Understanding how measles is likely to spread geographically and where best to concentrate interventions will be vital to an effective response.”

Measles epidemics often follow humanitarian crises because the infection is one of the most transmissible and vaccination rates tend to be lower.

The three main Ebola affected countries had seen a marked fall in cases in recent years due to vaccination efforts. Between 1994 and 2003, together they reported over 93,000 cases, but this fell to just under 7,000 in the decade from 2004.

Measles is just one of several childhood illnesses which have suffered limited vaccination distribution because of Ebola. Immunization against meningitis, tuberculosis, and polio has also been affected. Similarly, there has been a negative impact on interventions against malaria and HIV.

Source: University of Southampton

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