I noticed the disparity also. All I can add is som

I noticed the disparity also. All I can add is something I read about less MS cases near the equator. Diet may play a big role and we all know diabetes is on the rise too, mostly diet related and with inflammation from said. Vitamin D is a culprit as well, most people are D deficient.

<<Who gets MS?
Anyone may develop MS but there are some patterns. More than two to three times as many women as men develop MS and this gender difference has been increasing over the past 50 years. Studies suggest that genetic factors increase the risk of developing MS, but there is no evidence that MS is directly inherited. Environmental factors, such as low Vitamin D and cigarette smoking have also been shown to increase the risk of MS. MS occurs in most ethnic groups, including African-Americans, Asians and Hispanics/Latinos, but is most common in Caucasians of northern European ancestry.

How many people have MS?
Worldwide, more than 2.3 million people have a diagnosis of MS. In the United States a recently completed prevalence study, funded by the National MS Society, has estimated that nearly 1 million people over the age of 18 live with a diagnosis of MS. In 2016, the 21st Century Cures Act was signed into law, authorizing the Centers for Disease Control and Prevention (CDC) to create a National Neurological Conditions Surveillance System (NNCSS) to collect data on neurologic conditions to improve research and public health data on these conditions. The NNCSS received its first 5-year period of funding starting in fiscal year 2019 and the Society will ask Congress to continue its $5 million investment in this important System in fiscal year 2020.

The CDC is using multiple sclerosis and Parkinson’s disease, as demonstration projects to inform the creation of the Surveillance system and help the CDC determine the appropriate methodologies to use and identify areas of biggest impact. Using innovative methods and complex data sources, the CDC will gather information for these diseases and use similar methods to extend the NNCSS to other neurologic disease conditions.

This system will be informed by the Society’s prevalence initiative, a four-year study that used millions of health records to get a more accurate count of the number of people in the US living with MS. The study showed that nearly 1 million people in the United State live with MS - more than twice the number previously thought......

Can MS be cured?
Not yet. There are now FDA-approved medications that have been shown to "modify" the course of MS by limiting new areas of damage in the CNS, reducing the number of relapses and delaying progression of disability. In addition, many therapeutic and technological advances are helping with more effective symptom management. Advances in treating and understanding MS are made every year, hopefully moving research closer to identifying a cure.>>