How does measles affect the muscular system?

How does measles affect the muscular system?

Measles does not directly affect the muscular system. Overall, measles affects human physiology, which affects the muscular system. However, the exact interactions between measles and the muscular system are nebulus.

Measles is a single stranded negative sense RNA virus. Clinical diagnosis of measles requires the presence of the following: fever of at least 38.3°C (101°C), maculopapular (small raised discolored spots) rash of at least 3 days duration, and cough, coryza (respiratory inflammation), or conjunctivitis. Laboratory diagnosis of measles is accomplished by detection of measles virus-specifc immunologlublin M (IgM) or IgG antibodies, or measles virus RNA (1).

The measles virus is transferred to epithelial cells in the respiratory tract, oropharynx or conjunctivae. The virus proliferates in the respiratory mucosa, spreads to the lymph nodes, then spreads to the bloodstream via leukocytes. From this point the virus spreads to the spleen, lymphatic tissue, lung tissue, thymus, liver, and skin (2). The host immune response includes both an innate immune response and an adaptive immune response (in individuals vaccinated or previously exposed to the virus). The innate immune response includes activation of natural killer cells, increased production of interferon gamma and beta, interleukin (IL) 4 and 10, and activation of helper T cells 1 and 2 (Th1, Th2). These pro-inflammatory cytokines induce fever and may cause muscle pain (3). Measles virus induces immune suppression, causing susceptibility to secondary infections such as pneumonia and diarrhea that are primarily responsible for measles-associated morbidity and mortality. Thus, measles affects the muscular system to the extent to which pro-inflammatory conditions and secondary infections interact to affect the musculature system.

Of note are two other rare but serious complications due to measles. Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease that occurs in 0.1% of measles cases. Possibly due to an autoimmune response, ADEM can cause, among other symptoms, ataxia (in coordinated muscle movement) and myoclonus (involuntary muscle twitching) (4). Subacute sclerosing panencephalitis (SSPE) is thought to be related to persistent infection of measles in the central nervous system Stage II of SSPE is characterized, in part, by myoclonus (5).

1. Rainwater-Lovett K, Moss WJ. Measles (Rubeola). In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds.Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. Accessed May 11, 2016.

2. Moss, WJ, Griffin DE. Global measles elimination. Nature reviews microbiology; 2006, Vol.4(12), p.900-908.

3. Dinarello CA, Porat R. Fever. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds.Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. Accessed May 11, 2016.

4. Johnson RT, Griffin DE, Hirsch RL, Wolinsky JS, Roedenbeck S, Lindo de Soriano I, Vaisberg A. Measles encephalomyelitis--clinical and immunologic studies. N Engl J Med. 1984;310(3):137.

5. Dyken PR. Viral diseases of the central nervous system. In: Pediatric Neurology: Principles and Practice, Mosby, St. Louis 1994. p.670.