The Ebola outbreak in West Africa, which started in 2014, has claimed more than 10,000 lives so far. The Ebola virus causes a frightening illness with symptoms including fever, vomiting, and bleeding. In this most recent epidemic, nearly half the people known to be infected with the virus have died. Although the epidemic shows signs of waning, there is great concern about additional health problems in West Africa.

The three countries most affected in the recent epidemic, Liberia, Guinea, and Sierra Leone already had very weak health systems prior to the Ebola outbreak. Once Ebola hit, many health care workers became infected and died, making an already bad situation worse. The result, many fear, is that other diseases that were previously under control will become widespread. The disease of greatest concern is measles which is up to 10 times more infectious than Ebola. An unvaccinated person, if exposed to someone who has measles, has a 90 percent chance of getting infected. If a person with measles sneezes in a room and leaves, susceptible individuals could still be infected if they entered that room several hours later. As a consequence, if vaccination rates are low, measles can spread like wildfire. We have experienced this recently in the U.S., where a case of measles spread rapidly from an infected person in California, fueled by low vaccination rates based on misinformation about the vaccine. Although many see measles as a disease of the past, it still kills an estimated 100,000 people each year, worldwide.

In the affected countries in West Africa, prior to the Ebola outbreak, only about 70 percent of children were vaccinated against measles, much lower than the 95 percent rate needed to stem transmission of the disease. Researchers from a number of institutions in the U.S. and Sweden conducted an analysis to try to determine how the Ebola epidemic could affect vaccination rates in the most heavily affected countries, and what that would likely mean in terms of illness and death from measles. The scientists estimated that, prior to Ebola, there were nearly 800,000 children in Guinea, Sierra Leone, and Liberia who had not been vaccinated against measles. Based on the collapse of the health care system in these countries, they postulated a 75 percent reduction in measles vaccination rates, estimating that about 1.2 million children would be unvaccinated 18 months after the start of the Ebola outbreak. Of these children, it is thought that as many as 320,000 could get measles, and, at the high end, over 16,000 additional deaths could occur. If this prediction comes true, it would mean 50 percent  more people would have died from measles, as compared to Ebola.

This information highlights the importance of continued vaccination against diseases that many of us have considered conquered, like measles. When we are vaccinated, we protect others from getting infected, particularly those unable to benefit from vaccines because they are too young or too ill.

More information is available in the article Saki Takahashi and others, entitled “Reduced vaccination and the risk of measles and other childhood infections post-Ebola” in Science 347: 1240-1242, March 13, 2015.

Patrick Guilfoile has a doctorate in bacteriology and is the associate vice president at Bemidji State University.