Contents
Links to Alberta Curriculum
Grade 8
- I can interpret the healthy function of human body systems, and illustrate ways the body reacts to internal and external stimuli
- I can describe areas of scientific investigation leading to new knowledge about body systems and to new medical applications
Grades 8 and 9
I can apply the research process
- Integrate and synthesize concepts to provide an informed point of view on a research question or an issue
- Determine how information serves a variety of purposes and that the accuracy or relevance of information may need verification
Grade 9
- I can describe the effect of: bias; use of language; ethics; cost; time and timing; privacy; and cultural sensitivity on the collection of data.
- I can demonstrate an understanding of the role of probability in society.
Measles
Measles, also called red measles or rubeola, is an infectious disease caused by the measles virus.
Signs and symptoms
The average incubation period (the time from infection to the onset of signs and symptoms) of measles is generally 10–12 days (Moss, 2017). Measles begins with a fever, cough, coryza (runny nose), and conjunctivitis (pink eye), and within 3–4 days, a distinctive red rash appears on the face and behind the ears, and then spreads down the body.
Transmission
The measles virus spreads from person to person through small airborne and respiratory droplets (from breathing, speaking, sneezing, or coughing) that can remain suspended in the air for up to 2 hours (Moss, 2017). The infectious period (the time when the measles virus can be spread) lasts for about 4 days before and after the red rash appears, which increases the contagiousness of the measles virus.
Measles is one of the most contagious infectious diseases worldwide. The basic reproductive number (R0, the average number of secondary infections resulting from one typical infection in a susceptible population) of measles has been estimated to be 9–18 depending on setting (e.g., degree and frequency of contact) (Moss, 2017).
To achieve herd immunity, which interrupts the transmission of measles and protects those who cannot be vaccinated (e.g., infants <1 year of age and those with compromised immune systems), a population immunity threshold of 89–94% is required through vaccination or natural infection (Moss, 2017).
Complications from measles
Measles can be serious.
Common complications
- Ear infections (~10% of children with measles)
- Diarrhea (<10% of people with measles)
Serious complications
- Hospitalization (~1 in 5 people)
- Pneumonia (~1 in 20 children)
- Encephalitis (1 in 1000 children)
- Death (1–3 in 1000 children)
- Complications during pregnancy including low birth weight and preterm birth
(CDC, 2020)
Who is at highest risk?
- Young children <5 years of age
- Adults >20 years of age
- Pregnant individuals
- People with compromised immune systems (e.g., individuals with cancer or transplants who are taking immunosuppressive therapy)
- People who are undernourished
(Moss, 2017)
Immune amnesia
Measles infection is thought to damage and suppress the immune system by wiping out antibodies developed against pathogens that a person has previously been exposed to. This wiping-out of immune memory has been called immune amnesia.
Elimination–and recent outbreaks
In Canada, measles has been eliminated since 1998 (Public Health Agency of Canada, 2019).
In recent years, vaccine hesitancy as well as complacency about the risks of vaccine-preventable diseases have led to declines in measles vaccination rates, resulting in outbreaks in both Canada and the United States (Phadke, Bednarczyk, & Omer, 2020; Public Health Agency of Canada, 2019).
Outbreaks
Stories of families impacted by measles
Laurie’s vaccination story
Maggie’s story
Mobius’ story
Mobius’ parents shared their family’s story with the California Immunization Coalition at ShotByShot.org
Measles vaccine
The measles vaccine is the safest and most effective way to prevent measles (Moss, 2017). Usually, the measles vaccine is combined with other vaccines in the measles, mumps, and rubella (MMR) vaccine. The MMR vaccine contains weakened parts of these viruses that do not cause severe illness in people with healthy immune systems. After getting the vaccine, the body will create antibodies that recognize and fight these viruses.
The measles vaccine is safe and effective
Before the measles vaccine was used widely beginning in the 1980s, more than 2 million people worldwide died of measles each year (Moss, 2017). Today, more than 100,000 people worldwide die of measles each year. Increased global vaccine coverage is decreasing measles cases and deaths (World Health Organization, 2019).
Measles cases in Canada have decreased by >99% because of the measles vaccine (Public Health Agency of Canada, 2019).
(Image credit: Public Health Agency of Canada)
MMR vaccine does not cause autism
Many studies have found that there is no evidence that vaccines–including the measles, mumps, and rubella (MMR) vaccine–cause autism.
Many of these claims stem from a paper that was ultimately retracted from The Lancet (Wakefield et al., 1998) and whose lead author, Andrew Wakefield, was found to have engaged in scientific misconduct. As a result, Wakefield’s medical license was revoked.
Wakefield et al. paper
Background
In 1998, a prominent medical journal, the Lancet, published a case series (Wakefield et al., 1998) assembled by Andrew Wakefield and others. The paper reported on 12 children with gastrointestinal symptoms, and suggested a link between the measles, mumps, and rubella (MMR) vaccine and autism.
Refutation
Not longer after the Wakefield et al. paper was published, concerns were raised and research was conducted that refuted Wakefield et al.’s suggested link between MMR vaccine and autism (Rao & Andrade, 2011; Taylor et al., 1999).
Retraction
In 2004, 10 of 12 co-authors of the paper issued a retraction statement that addressed some of these concerns: “no causal link was established between MMR vaccine and autism as the data were insufficient” (Murch et al., 2004; Rao & Andrade, 2011). The Lancet also acknowledged that Wakefield et al. failed to disclose conflicts of interest (Horton, 2004).
The Wakefield et al. paper was fully retracted by the Lancet in 2010 (The Editors of the Lancet, 2010). By this time, it was established that Wakefield et al. had committed ethical misconduct, by failing to obtain necessary ethical clearance, as well as scientific misconduct, by misrepresenting how participants were recruited (Rao & Andrade, 2011).
Consequences
The Wakefield et al. paper has had lasting consequences.
In the United Kingdom, MMR vaccination rates hit a low in 2003–2004 (Cockman, 2011). It has taken considerable public health intervention to counter increase vaccination rates. Cockman (2011) provides a quality improvement report for a London Borough that outlines how the rates for the first MMR vaccine before 2 years of age increased from 80% in September 2009 to 94% in March 2011.
Vaccine hesitancy, skepticism, and refusal continue to be significant factors in preventable outbreaks of measles around the world (Phadke et al., 2020).
Areas for discussion with students and further activities
- Ethics and conflicts of interest
- Scientific rigor and integrity
- Study design
- Sample selection and representativeness
CDC. (2020). Complications of measles. Retrieved from https://www.cdc.gov/measles/symptoms/complications.html
Cockman, P., Dawson, L., Mathur, R., & Hull, S. (2011). Improving MMR vaccination rates: herd immunity is a realistic goal. BMJ , 343, d5703. https://doi.org/10.1136/bmj.d5703
Horton, R. (2004). A statement by the editors of The Lancet [Review of A statement by the editors of The Lancet]. The Lancet, 363(9411), 820–821. https://doi.org/10.1016/S0140-6736(04)15699-7
Kooistra, B., Dijkman, B., Einhorn, T. A., & Bhandari, M. (2009). How to design a good case series. The Journal of Bone and Joint Surgery, 91, 21–26. https://doi.org/10.2106/JBJS.H.01573
Moss, W. J. (2017). Measles. The Lancet, 390, 2490–2502. https://doi.org/10.1016/S0140-6736(17)31463-0
Murch, S. H., Anthony, A., Casson, D. H., Malik, M., Berelowitz, M., Dhillon, A. P., Thomson, M. A., Valentine, A., Davies, S. E., & Walker-Smith, J. A. (2004). Retraction of an interpretation. The Lancet, 363(9411), 750. https://doi.org/10.1016/S0140-6736(04)15715-2
Phadke, V. K., Bednarczyk, R. A., & Omer, S. B. (2020). Vaccine Refusal and Measles Outbreaks in the US. Journal of the American Medical Association, 324(13), 1344–1345. https://doi.org/10.1001/jama.2020.14828
Public Health Agency of Canada. (2019, April 8). Measles in Canada. Retrieved from https://www.canada.ca/en/public-health/services/diseases/measles/measles-in-canada.html
Rao, T. S. S., & Andrade, C. (2011). The MMR vaccine and autism: Sensation, refutation, retraction, and fraud. Indian Journal of Psychiatry, 53(2), 95–96. https://doi.org/10.4103/0019-5545.82529
Taylor, B., Miller, E., Farrington, C. P., Petropoulos, M. C., Favot-Mayaud, I., Li, J., & Waight, P. A. (1999). Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. The Lancet, 353(9169), 2026–2029. https://doi.org/10.1016/s0140-6736(99)01239-8
The Editors of The Lancet. (2010). Retraction–Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet, 375, 445. https://doi.org/10.1016/S0140-6736(10)60175-4
Wakefield, A. J., Murch, S. H., Anthony, A., Linnell, J., Casson, D. M., Malik, M., … Walker-Smith, J. A. (1998). RETRACTED: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet, 351, 637–641. https://doi.org/10.1016/s0140-6736(97)11096-0
World Health Organization. (2019). Measles. Retrieved from https://www.who.int/news-room/fact-sheets/detail/measles