Over the last two months, a disease which had been effectively eradicated in North America made a re-appearance. Over 100 people in California were diagnosed with measles, and some cases were also reported in other western states in the USA, in Mexico, and in Ontario and Québec. After questioning those who were infected, it was discovered that many of them had visited Disneyland over the Christmas break in 2014, or had come into contact with someone who had visited Disneyland. But why is a disease which was thought to have been eradicated still causing outbreaks?
Measles, which is caused by the virus of the same name, is an illness which can cause fever, cough, runny nose, conjunctivitis (red eyes), and/or a rash. It primarily attacks the respiratory and digestive systems, and thus is spread by coughing or sneezing in the presence of other people. While the majority of people who get measles recover fairly quickly, possible complications can lead to pneumonia, diarrhea, and even death. In developed countries such as the US and the UK where good medical treatment is available, measles is rarely fatal, killing only 0.1% of infected people, but the disease is deadlier in places like Afghanistan or Ethiopia, which have reported death rates of 10-20%. Similar to chickenpox, measles primarily affects children, and once someone recovers from it, they have permanent immunity.
Measles has a long history – DNA studies suggest it evolved from rinderpest, a virus affecting cows in the Middle Ages, and it was first documented by the Persian doctor Mohammed Ar-Razi in the 9th century. It killed many in the Americas when Europeans brought the disease over during the Age of Discovery, as the natives had no previous exposure to the disease. For centuries, measles was a rite of passage – almost every child had it, and you just had to hope that the one time you got it wouldn’t be fatal. However, in the 1950s, doctors were able to isolate the virus and prepare a vaccine to protect against it. The vaccine was later combined with two other vaccines to produce an all-in-one vaccine against measles, mumps, and rubella. This MMR vaccine is currently administered in two doses to children when they are about one year old. By 2000, measles and rubella were completely eradicated in North America, and mumps had become rare. Studies have shown the MMR vaccine to be 93-99% effective, and reduce the odds of getting measles by 60-80%.
However, there have been several hiccups in the drive to eradicate measles. In 1998, the medical journal The Lancet published an article by several British scientists, which suggested a link between the MMR vaccine and increased rates of autism. The study’s lead author, Andrew Wakefield, recommended that parents should have their children vaccinated with three separate shots for measles, mumps, and rubella instead of taking the all-in-one vaccine. It was later discovered that Wakefield had a conflict of interest, as he had been paid £400,000 by a legal firm which was preparing a lawsuit against a vaccine manufacturer, and in fact had applied for a patent for a new measles vaccine. The UK’s General Medical Council eventually concluded that Wakefield had taken a bribe and fudged the numbers in order to support a false conclusion, and banned him from practicing medicine. No legitimate evidence has been found to suggest a link between the MMR vaccine and autism.
However, the damage was done. The alleged autism link caused many parents not to vaccinate their children at all, and there was an increase in the incidence of measles in Britain after 1998. There are also some parents who refuse on principle to vaccinate their children. Objections may result from a refusal to carry out any task promoted by the government to demonstrate personal, a misunderstanding of what vaccines do, or due to membership in a vaccine-discouraging religious group such as the Christian Science movement. However, objecting parents are rather few, and a recent study by the Center for Disease Control (CDC) showed that 91% of American children had been given at least one dose of the MMR vaccination.
The Center for Disease Control (CDC) is now hypothesizing that an infected tourist from a country where measles is still in the wild took the virus to Disneyland and started the outbreak. However, the outbreak has spread primarily among unvaccinated children within North America. This suggests that it could have been prevented if vaccination rates were higher. In an interview with NBC News, President Obama, who in his 2008 election campaign had called for “further research” into possible vaccine-autism links, now stated “the science is clear” and recommended that every parent vaccinate their kids. Unfortunately, the issue quickly became politicized. Gov. Chris Christie and Sen. Rand Paul, both campaigning for President in 2016, spoke in support of parental freedom to choose whether to get their children vaccinated. While this view appeals to libertarians, proponents of vaccination point out that failing to get a child vaccinated not only affects the child, but also those around them.
If you were born in Canada after 1980, provided your parents didn’t exempt you, you should have received two doses of the MMR vaccine already. If you are unsure whether or not you have immunity to measles, ask your doctor – it may be possible to determine if you are immune to measles with a blood test. If it turns out that you have neither had measles nor been vaccinated against it, it would probably be wise to ask to get vaccinated – that’s one fewer person the disease can be spread through. (Warning: This article is for informational purposes only and I am not qualified to provide medical advice. Please consult a registered physician for professional medical advice before doing anything.)
References:
“Measles Vaccine”, in Canadian Immunization Guide. (2014). http://www.phac-aspc.gc.ca/publicat/cig-gci/p04-meas-roug-eng.php
R. Perry and N. Halsey. (2010). “The Clinical Significance of Measles: A Review”, in Journal of Infectious Diseases, vol. 189, no. 9 (supplement), pp. 4-16.
Center for Disease Control. (2015). U.S. Multi-state Measles outbreak. http://emergency.cdc.gov/han/han00376.asp
I. Barrabeig et al. (2011). “MMR vaccine effectiveness in an outbreak that involved day-care and primary schools”, in Vaccine, vol. 29, no. 45, pp. 8024-8031.
S. Akramuzzaman et al. (2002). “Measles vaccine effectiveness and risk factors for measles in Dhaka, Bangladesh”, in Bulletin of the World Health Organization, vol. 80, no. 10, pp. 776-782.
H. Jick and K. Hagberg. (2010). “Measles in the United Kingdom 1990-2008 and the effectiveness of measles vaccines”, in Vaccine, vol. 28., no. 29, pp. 4588-4592.
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