Epidemiology – the study of the natural history of disease – is helping medical experts make remarkable strides in finding the cause of multiple sclerosis (MS).
Dr. John F. Kurtzke, consultant in neurology and neuroepidemiology at the Department of Veterans Affairs (VA) Medical Center in Washington, D.C., and professor emeritus of neurology at Georgetown University, since the 1950s has spent his career researching population-based measures of the frequency of MS in hopes of linking the disease to a specific cause.
Kurtzke discussed the epidemiologic findings at Paralyzed Veterans of America’s annual Summit+Expo, which took place Aug. 27-29, 2013, in Orlando, FL.
Research into the epidemiology of MS began with community surveys that divided the world into three regions of high (30+ per 100,000), medium (5 to 29) and low (less than 5) prevalence rates. The first of these surveys showed high regions comprised northwestern Europe, southern Canada, the Northern United States, New Zealand and southeastern Australia. More and more of the world has since fallen into those higher prevalence rates, Kurtzke said, pointing to numerous surveys over the past 50 years that indicate MS as an acquired, place-related disease, warranting search for an environmental cause.
“MS is limited to humans, and this kind of distribution is what one might expect for a human disease that is transmitted from one person to another,” Kurtzke said. “However, if there is anything that we know about this disorder, it is that neurologically affected persons do not transmit anything to anyone. Further, clinical cases of MS are far too few to maintain any infection in a population.”
Still, countering those points is the possibility that MS may be transmissible only in a pre-neurologic phase, or that the disease could be a far more widespread illness than clinical cases indicate, Kurtzke said.
Kurtzke, a veteran of World War II, began studying the epidemiology of MS after discovering during his residency at the VA Hospital in the Bronx, N.Y., that a clinical trial for treatment for the disease had no effect. It was then that the participants began investigating MS among the 16 million persons at prime age for symptom onset who had served in the military in World War II.
Nationwide surveys of each country of Fennoscandinavia and Switzerland showed high rates of MS in single contiguous regions of each land, suggesting an origin of MS in south-central Sweden that spread south and into Wisconsin and Minnesota from emigrants of the high areas of Norway and Sweden in the latter 19th century.
A quarter-century of research in the Faroe Islands also indicates no cases of MS among native residents until 1943, leading researchers to conclude that the disease was introduced to the islands by British military forces stationed there from April 1940 to September 1945.
Researchers then concluded that British troops had brought a previously unknown, widespread and asymptomatic infection called Primary Multiple Sclerosis Affection (PMSA), an acute form of gastroenteritis. Among those affected by PMSA at ages 11 to 45, the infection persisted for years in the gut, with early spread to intestinal lymph nodes and, in a few of the affected, spread to the central nervous system via blood and cerebrospinal fluid, Kurtzke said.
“Clinical multiple sclerosis could then possibly be the rare result of a single persistent infection … This is today a testable hypothesis,” Kurtzke said. “This seems about as far as epidemiology could be expected to go in seeking a specific cause, and I would now pass that torch to our virology colleagues. For even if everything I have presented is correct, without laboratory proof the best I can do is to join Churchill in his well-known comment after the 1942 victory at El Alamein: ‘Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.’”
For more information or to register for Paralyzed Veterans of America’s 2014 Summit+Expo taking place Aug. 26-28, 2014 in Las Vegas, NV, visit this link.
Return to Summit 2013: Research Highlights
Brittany Ballenstedt is a freelance journalist whose work has appeared in several publications, including Government Executive, National Journal, Technology Daily and NextGov.com.