Occurrence of multiple sclerosis in the north and south of New Zealand.

The Increasing Prevalence of Multiple Sclerosis in New Zealand

“…2) at distinct latitudes from north to south: Waikato (1981) [24], Bay of Plenty (2001) [21], Wellington (1968 and 1983) [23,25], Christchurch (1971) [22] and Otago-Southland (1981) [24]. In all the studies, the diagnosis was confirmed by study neurologists.…”

“…The crude prevalence for the 5 earlier regional studies [21,22,23,24,25] ranged from 23.6 to 68.5/100,000 population (table 1); in the same regions in 2006 [18], it ranged from 47.6 to 134.2/100,000 population.…”

“…The study of Skegg et al [24] conducted in 1981 showed a 2.9 times higher prevalence of MS in the southern regions (Otago-Southland) of NZ than the northern regions (Waikato). The NZNMSPS (2006) showed a similar gradient (2.8 times) in prevalence between the same southern and northern regions, indicating a constant gradient in the prevalence of MS in NZ over the period of 25 years between the studies (table 1).…”

“…The 6 included studies [18,21,22,23,24,25] were conducted between 1968 and 2006, and all were considered to be of ‘very good' quality based on the study's criteria for quality assessment. All 6 studies used population at risk as a denominator based on contemporary census data.…”

Association of UV radiation with multiple sclerosis prevalence and sex ratio in France

“…Exposure data on individual patients may be most useful in populations or locations that are exceptions to the UV gradient hypothesis. These include the reverse latitude gradient observed in Norway, 29 prevalence variability among different ethnic groups in the same region, 6,28,30 resistance to MS in indigenous populations, 29,31,32 and the high prevalence of MS in Sardinia, 33 among others. Such exceptions may result from putative protective environmental factors including fish-rich diets, 29,34 protective/predisposing genetic factors, cultural practices, or other as yet unidentified reasons.…”