Transmission and Treatment of Multiple Sclerosis

Who is at risk?

While the cause of multiple sclerosis is still unknown, there are certain populations known to be at higher risk for the disease. As mentioned in the previous post, these factors include: genetics, environment, and exposure to certain pathogens (Loma, 2011).

Diagram of human chromosome 6, detailing the HLA locus.

The genetic component of multiple sclerosis can be observed in instances of higher frequency of the disease among related individuals. If someone has a first degree relative with multiple sclerosis, their chance of contracting the disease increases "40-fold" (Loma, 2011). Multiple loci in various chromosomes are suspected to contribute to the genetic basis of the disease. However, the HLA locus on chromosome 6 is the current front-runner thought to cause the most susceptibility (Loma, 2011).

The second component, environment, can be seen by analyzing prevalence of the disease in different global regions. Higher latitudes (both north and south of the equator) are associated with higher prevalence of multiple sclerosis (Alharbi, 2015). Even when adjusted for genetic similarities within geographical regions, latitude still has a significant affect on risk (Simpson, 2011). Newer studies suggest that this environmental risk factor is tied to vitamin D intake during adolescence. Individuals in higher latitudes have greater instances of vitamin D deficiency because of less sun exposure (Alharbi, 2015). While the protective effects of vitamin D are not fully understood, it is clear that vitamin D exposure (through sunlight or oral supplements) correlates to lower risk for the disease. 

Sufficient levels of vitamin D in the blood lower risk for MS.

The final risk factor speculated to be associated with multiple sclerosis is exposure to certain pathogens. In cases of  Relapsing-Remitting Multiple Sclerosis, certain viral infections are known to cause relapses (Loma, 2011). If viruses can trigger a relapse, perhaps they are also responsible for onset of the disease. Herpes virus type 6, Epstein Barr virus, and the bacteria mycoplasma pneumoniae are all being researched for a possible link to MS (Loma, 2011). There is significant evidence that individuals with multiple sclerosis have higher numbers of Epstein Barr virus antibodies in their blood and cerebrospinal fluid (Pender, 2014). 

Viral infections alone are not likely the cause of multiple sclerosis. However, the combination of certain viral exposure with genetic predisposition and vitamin D deficiency likely put an individual at much greater risk for the disease. 

Transmission

Multiple sclerosis is not contagious horizontally between hosts (NMSS - FAQ). Because there seems to be a genetic component tied to the disease, one could say that it is transmissible vertically between parents and their offspring. However, just because an individual has the genetic markers at the HLA locus, does not mean that they will necessarily develop the disease.

Treatment/Prevention

Unfortunately, there is no known cure for multiple sclerosis (Loma, 2011). Patients diagnosed with the disease receive treatment to manage their symptoms and relapse periods. According to the National Multiple Sclerosis Society, treatment falls under five categories:

1. Modifying the disease course with drugs that lessen the frequency of relapses. These medicines can be injected intravenously like Avonex, or taken orally like Gilenya (NMSS - Treating MS). 

2. Treating exacerbations or inflammation in the nervous system with corticosteroids like prednisone. Not all exacerbations need to be treated medically. However, severe inflammation can often cause debilitating symptoms that interfere with daily life and treatment is needed (NMSS - Treating MS).

3. Managing symptoms of multiple sclerosis like fatigue, walking difficulties, and bladder problems. Because these symptoms are not specific to MS, they can be treated with other methods (NMSS - Treating MS).

4. Rehabilitation programs that help improve an individual's everyday functioning. These programs can focus on cognitive rehabilitation or physical/occupational therapy depending on the loss of function (NMSS - Treating MS).

5. Emotional and mental health support is crucial for chronic, incurable diseases like multiple sclerosis. Multiple sclerosis, being a disease that affects the nervous system, can cause depression, anxiety, and mood swings that should be treated by physician or counselor (NMSS - Treating MS).

Eight of the more than 12 FDA approved drug treatments for MS.

As the causes of multiple sclerosis become better understood, prevention methods can be implemented. Based on current science, researchers suggest that vitamin D intake during childhood and adolescence can significantly decrease the risk for MS (Dudani, 2011). Taking vitamin D supplements is a safe preventative measure that avoids the carcinogenic risks of sun exposure. 

References:

Alharbi, F. M., (2015). Update in vitamin D and multiple sclerosis. Neurosciences, 20(4), 329-335. http://doi.org/10.17712/nsj.2015.4.20150357

Dudani, S. J., Kalhan, S., & Sharma, S. P. (2011). Vitamin D and multiple sclerosis: Potential pathophysiological role and clinical implications. International Journal of Applied and Basic Medical Research, 1(2), 71–74. http://doi.org/10.4103/2229-516X.91146

Loma, I., & Hayman, R. (2011). Multiple Sclerosis: Pathogenesis and Treatment. Current Neuropharmacology, 9(3), 409-416. http://doi.org/10.2174/157015911796557911

Multiple Sclerosis FAQs. (2017). National Multiple Sclerosis Society. Retrieved from: http://www.nationalmssociety.org/What-is-MS/MS-FAQ-s

Pender, M. P. & Burrows, S. R. (2014). Epstein-Barr virus and multiple sclerosis: potential opportunities for immunotherapy. Clinical & Translational Immunology. http://doi.org/0.1038/cti.2014.25

Simpson, S., Blizzard, L., Otahal, P., Van der Mei, I., & Taylor, B. (2011). Latitude is significantly associated with the prevalence of multiple sclerosis: a meta-analysis. Journal of Neurology, Neurosurgery, and Psychiatry. 82(10), 1132-1142. http://doi.org/10.1136/jnnp.2011.240432

Treating Multiple Sclerosis. (2017). National Multiple Sclerosis Society. Retrieved from: http://www.nationalmssociety.org/Treating-MS/Comprehensive-Care

Image Sources (in order of appearance):

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