Prevalence of multiple sclerosis and environmental factors in Kerman province, Iran

Objective: In this study we investigated the epidemiology of MS and some related environmental factors in Kerman province, southeastern Iran. Methods: The MS diagnosis was based on the revised Mc-Donald criteria. The patients were those registered at the Iran MS society, Kerman branch; those in the MS registration centers of Kerman and Rafsanjan University of Medical Sciences, and the Department of Neurology at Shafa Medical Center were studied. Results: The prevalence of MS was 31.5 per 100,000 population in Kerman province, and 57.3 per 100,000 population in Kerman city. The male to female ratio was 1:3. Average age at onset was 28.35 years, and 3.9% of cases were early onset at ≤16 years of age. A linear relationship was observed between prevalence and average environmental temperature as prevalence tended to be lower in areas where the annual average temperature was higher. However, in the town of Shahrbabak which has cold weather, prevalence was low, which might be related to the presence of copper in this area. Average disability was 4.5± 1.9 (4.83 ± 1.9 in men and 4.26 ± 1.8 in women, p=0.0035) on the Kurtzke Disability Status Scale. The mean duration of illness was 8.2 ± 1 year. Almost all patients in this study used beta-interferon for a period of at least 4 years. Conclusion: The prevalence of MS in Kerman province was 31.5 per 100,000 people. A linear relationship between an increase in prevalence and low average temperature was observed. Copper may have a preventive effect. Neurology Asia 2013; 18(4) : 385 – 389 Address correspondence to: Hossein Ali Ebrahimi M.D No 14 – sharghi 3 – 17 Parvin e Etesami avenue Kerman – Iran. Tel/Fax: +983412467500, e-mail: [email protected], [email protected] INTRODUCTION Multiple sclerosis (MS) is a complex neurological condition with associated loss of myelin and axons. This disease is the most common human demyelinating illness and afflicts twice as many women as men. The average age at onset of illness is 30 years, and almost 1,000,000 people in the world between the ages of 17–65 have been afflicted. The onset of MS typically is in young adults, and thus it is associated with long term physical effects. The socio-economic impact may be greater than that of Alzheimer’s and myocardial infarction due to its extended duration of illness. The highest prevalence of MS is in Europe and North America. However, evidence shows an increase of this disease in arid regions and developing countries. The MS prevalence rate in Tehran-Iran is estimated to be 51.9 per 100,000 population; and in Isfahan-Iran, 43.8 per 100,000 population. It is believed that MS is a complex disease caused by the interaction of genetics and the environmental factors. There are many environmental factors that are thought to affect MS. They are: viral infections, smoking, improved hygiene, ultraviolet radiation such as living in high latitudes areas where ultraviolet radiation is low, vitamin D metabolism, accumulation of copper, lead, and iron; reduction in zinc, magnesium, selenium, vitamins B2, B6, D, E, and essential fatty acids. In this study, we investigated how temperature is associated with MS, focusing on the vast province of Kerman which is composed of different cities of varying climates.