By Isha Verma
Epidemic outbreaks have been studied by epidemiologists for centuries. The nature of airborne, waterborne and foodborne illness is a fiery topic, with the focus being primarily on how infectious diseases can be treated. However, scientists are now starting to examine the relationships between the development of a disease and its overall toll on the immune system. More specifically, recent discoveries have confirmed that the onset of measles can lead to the long-term suppression of the immune system.
Measles, a highly contagious disease caused by a virus called Morbillivirus1, is preventable through vaccination but still is responsible for more than 100,000 deaths per year2. Transmitted through the air, the disease can elicit a range of detrimental effects on the immune system and may result in death3,4. With the virus attacking the immune cells of the body, evidence has shown that measles has the ability to inhibit immunological memory2, a term used to describe the processes by which the immune system knows how to fight off viral infections. This occurs even if previous exposure was introduced through vaccination. It has been known to create these effects on a short-term time scale, but these new findings related to its detrimental effects on immunological memory has improved our understanding of its long-term impacts. The term “immune amnesia” has consequently been coined.
Two studies published in the Science and Science Immunology Journal have explored the phenomena of immune amnesia and the mechanisms by which it takes such a toll on the body. Both studies examined blood samples in a cohort of unvaccinated children, pre-measles and post-measles, with both studies culminating similar results after analysis.
In the first study, B lymphocytes were reduced in the post-measles blood sample. B lymphocytes can identify microbial infections, triggering an immunological response towards them4. With depleted levels of these cells after measles exposure, the immune system cannot create a strong immunological response5. The second study used a similar approach by analyzing the impact of measles on immunological memory, and how it leaves the body susceptible to developing infection on a long-term scale. The results concluded that after comparing the blood samples of pre-measles and post-measles, a range of 11 to 73% of preexisting, pathogen-specific antibodies were eliminated2, overall creating vulnerability to future infection.
Both studies were able to confirm the effects which the onset of measles creates on the immune system in children through the biological evidence of depleted B lymphocytes and antibodies in the blood. Given the implication that measles is able to generate immune amnesia by creating a decline in immunological memory functions, care must be taken to address its contribution towards leaving the body at a higher risk of developing viral infections in the future.
References
1. Naim HY. Measles virus [Internet]. Human vaccines & immunotherapeutics. Taylor & Francis; 2015 [cited 2019Nov29]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514292/
2. Mina MJ, Kula T, Leng Y, Li M, Vries RDde, Knip M, et al. Measles virus infection diminishes preexisting antibodies that offer protection from other pathogens [Internet]. Science. American Association for the Advancement of Science; 2019 [cited 2019Nov13]. Available from: https://science.sciencemag.org/content/366/6465/599
3. Williams R. Measles Leaves the Immune System Vulnerable to Other Diseases [Internet]. The Scientist Magazine®. 2019 [cited 2019Nov13]. Available from: https://www.the-scientist.com/news-opinion/measles-leaves-the-immune-system-vulnerable-to-other-diseases-66661
4. Wei-Haas M. Measles vaccines protect against more than just measles. Here's how. [Internet]. Measles can cause 'immune amnesia'. Here's what that means. 2019 [cited 2019Nov13]. Available from: https://www.nationalgeographic.com/science/2019/03/measles-vaccine-protect-disease-immune-amnesia/
5. Cano RLE. Introduction to T and B lymphocytes [Internet]. Autoimmunity: From Bench to Bedside [Internet]. U.S. National Library of Medicine; 2013 [cited 2019Nov13]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459471/
6. Petrova VN, Sawatsky BX, Han AM, Laksono BA, Walz LDde, Parker Evon, et al. Incomplete genetic reconstitution of B cell pools contributes to prolonged immunosuppression after measles [Internet]. Science Immunology. American Association for the Advancement of Science; 2019 [cited 2019Nov13]. Available from: https://immunology.sciencemag.org/content/4/41/eaay6125