Related Experiment Videos
Multiple sclerosis in the Faroe Islands. III. An alternative assessment of the three epidemics
1Neuroepidemiology Research Program, Veterans Administration Medical Center, Washington, DC.
Abstract:
Among 32 resident Faroese, clinical MS began between 1943 and 1973 and comprised 3 epidemics, each one significantly later in time and lower in incidence than the preceding. This is confirmed by the present division of the cases of the epidemics according to the calendar time when the patients attained age 11. The risk of MS for Faroese of Epidemic I, (those who acquired the disease from asymptomatic British troops in the World War II occupation), was 18 per 10,000. Depending on the minimum population number required for transmission, the MS risk for Epidemic II was 15 per 18 per 10,000, and for Epidemic III (under our second model) 9 or 11 per 10,000, none differing significantly from Epidemic I. We conclude that the primary MS affection (PMSA) is a single, widespread, specific, systemic infectious disease whose acquisition in virgin populations follows 2 years of exposure starting between age 11 and 45, which then produces clinical neurologic MS (CNMS) in only a small proportion of the affected after an incubation period of 6 (virgin populace) or 12 (endemic areas) years, and which is transmissible only during part or all of this systemic PMSA phase that ends by age 27 or younger.
Insights
Multiple sclerosis (MS) in the Faroe Islands occurred in three distinct epidemics, suggesting a widespread infectious origin. The disease appears to be acquired in adolescence and early adulthood, with a long incubation period before clinical symptoms emerge.
Area of Science:
- Epidemiology
- Infectious Diseases
- Neurology
Background:
- Multiple Sclerosis (MS) incidence in the Faroe Islands has been historically high, with distinct epidemic patterns observed.
- Previous studies suggested a potential link between MS and environmental or infectious factors in isolated populations.
Purpose of the Study:
- To analyze the temporal and incidence trends of three distinct Multiple Sclerosis (MS) epidemics in the Faroe Islands.
- To investigate the characteristics of primary MS affection (PMSA) and its relationship with clinical neurologic MS (CNMS).
Main Methods:
- Retrospective analysis of MS cases among Faroese residents from 1943 to 1973.
- Categorization of cases based on epidemic periods and age of onset (specifically age 11).
- Calculation of MS risk per 10,000 population for each epidemic wave.
Main Results:
- Three MS epidemics were identified, occurring sequentially with decreasing incidence.
- The risk of MS for the first epidemic, linked to World War II British troops, was 18 per 10,000.
- Subsequent epidemic risks (Epidemic II: 15-18/10,000; Epidemic III: 9-11/10,000) did not significantly differ from the first, suggesting a common underlying cause.
Conclusions:
- Clinical MS (CNMS) likely results from a single, widespread, systemic infectious disease (primary MS affection - PMSA).
- PMSA acquisition occurs in susceptible populations between ages 11 and 45, with transmission possible during a specific phase.
- A significant incubation period (6-12 years) precedes CNMS, with only a fraction of infected individuals developing clinical disease.