~Written by Theresa Majeski (Contact: theresa.majeski@gmail.com)
Also published on Global Contagions
Humanity has only truly conquered one human infectious disease, smallpox. Smallpox was successfully eradicated in 1977 after causing between 100 and 300 million deaths in the 20th century. Strides are being made to make polio the second eradicated infectious disease. Polio eradication efforts have been ongoing for almost 30 years, costing nearly 11 billion dollars. The World Health Organization (WHO) set a goal for polio eradication by 2000 but, 16 years later, that goal has yet to be achieved for reasons such as oral polio vaccine (OPV) effectiveness, armed conflict, and myths about vaccine dangers. The global public health community has been “burned” by the polio eradication campaign and may not have the money or energy for another global eradication campaign, especially since the polio campaign is still ongoing. Even if the global health community is burnt out on polio eradication efforts, is it time to turn our attention toward measles eradication?
Measles, along with smallpox and polio, is one of the very few diseases that meets the criteria necessary for eradication. Measles cases can be easily diagnosed due to the characteristic rash, the vaccine is incredibly effective, and there is no animal host where the virus can hide. Perhaps most importantly, measles transmission has been eliminated in large geographic areas, demonstrating that eradication may be feasible.
Number of reported measles cases from April 2015 to September 2015 (6 months); Photo Credit: World Health Organization
Measles is a deadly disease. In 2013, measles killed an estimated 145,000 people, mostly children in Africa, while leaving countless others deaf, blind, or otherwise disabled. To prevent measles individuals need to receive two vaccinations, which are 99% effective at preventing measles. While the number of children receiving measles vaccinations has risen over the past decade, there are still a handful of countries where children aren’t receiving vaccines (Democratic Republic of Congo, Ethiopia, Nigeria, India, Pakistan). Even places like the United States and some countries in Europe, which have eliminated measles locally, are seeing outbreaks due to imported cases. Until measles is eradicated, imported cases will continue to pop-up in countries without local transmission.
While measles meets the criteria for eradication efforts, there are still challenges to achieving that goal. One major challenge is that measles is incredibly contagious; infectious droplets can linger in the air for up to two hours, infecting unsuspecting people. To interrupt measles transmission, over 95% of the population needs to be vaccinated, compared to only 80% for smallpox and polio. The measles vaccine is also harder to deliver than the OPV, which is administered via a few drops in a child’s mouth. The measles vaccine must be given via injection, thus trained staff is necessary, and the vaccine has to be reconstituted in the field (liquid added to the powder vaccine to make the complete vaccine). Once reconstituted, the vaccine is only viable for six hours, which isn’t much of an issue for large vaccination campaigns but becomes problematic when only one or two children need to be vaccinated.
As with many global public health campaigns, governments and non-governmental organizations donate money to help high-risk countries control the spread of measles. In 2009, the global recession hit and measles eradication efforts lost significant funding. Mass vaccination campaigns were canceled or reduced and routine vaccination programs suffered. Following the reduction in vaccinations the number of measles cases exploded in southern African countries, going from 170,000 in 2008 to 200,000 in 2011. Added to these challenges is the perception of measles in high-income countries. Even though measles is a deadly disease, many in high income countries view measles as a minor illness with a rash and fever; certainly not something worth spending billions of dollars on over the course of many years.
Source: Butler D (2015). Measles by the numbers: A race to eradication. Nature 518 (7538): 148-149. doi: 10.1038/518148a.
Measles eradication is feasible. Measles meets the criteria necessary for eradication; it is easily diagnosed, it has an effective vaccine, and humans are the only host. It has been successfully eliminated in large areas of the world (for example, all 35 countries of the Americas eliminated measles in 2002), demonstrating that it is possible to at least end local transmission. However, significant challenges do exist. While the global health world may be hesitant to embark on another “eradication” campaign after the continued struggle with eradicating polio, perhaps it’s best to start eradicating measles without labeling it an “eradication” campaign. Avoiding the “eradication” label may help prevent critics who are hesitant about taking on another potentially long and expensive eradication campaign, especially as the polio eradication campaign is still ongoing. Regardless of the use of the word “eradication” in the efforts to rid the world of measles, without measles in the world, lives will be saved. Let’s ensure measles is added to the very short list of human diseases we’ve eradicated.