Multiple sclerosis in the Faroe Islands: an epitome

Area of Science:

• Epidemiology
• Neurology
• Infectious Disease

Background:

• The Faroe Islands have a unique epidemiological profile for multiple sclerosis (MS).
• MS incidence in the Faroes has been studied for decades, revealing distinct patterns.
• Understanding the environmental and infectious factors contributing to MS is crucial.

Purpose of the Study:

• To investigate the historical occurrence and transmission patterns of multiple sclerosis (MS) in the Faroe Islands.
• To identify potential environmental or infectious triggers for MS outbreaks.
• To characterize the proposed primary multiple sclerosis affection (PMSA) and its relationship to clinical MS.

Main Methods:

• Longitudinal study of MS cases in the Faroe Islands from 1900 to 1998.
• Prevalence and incidence rate calculations, age-adjusted to the 1960 US population.
• Epidemiological modeling to analyze disease transmission and cohort effects.
• Hypothesis generation regarding infectious etiology based on historical events (WWII).

Main Results:

• MS prevalence in 1998 was 66/100,000, with higher rates in women (100/100,000) than men (34/100,000).
• Four distinct MS epidemics were identified, with symptom onset beginning in 1943.
• Transmission models suggest an infectious agent (PMSA) introduced during WWII, with a latency period before clinical MS manifestation.
• Exposure from age 11 in a high-risk area for at least 2 years is required for MS acquisition.

Conclusions:

• The Faroe Islands' MS epidemic pattern supports an environmentally or infectious-induced etiology, potentially linked to WWII troop presence.
• The concept of primary multiple sclerosis affection (PMSA) as a precursor to clinical MS is proposed.
• The geographically isolated and stable nature of MS in the Faroes makes it an ideal location for further etiological research.