Multiple sclerosis in KwaZulu Natal, South Africa: an epidemiological and clinical study

Background Since the study by Dean, almost 40 years ago, there has been no systematic South African study on the prevalence of multiple sclerosis (MS) using the modern diagnostic criteria. KwaZulu-Natal (KZN), one of the nine provinces in South Africa, is home to 9.9 million people belonging to all racial groups. Aim To determine the period prevalence of MS in KZN in the different racial groups, using the revised McDonald's criteria. Methods The charts of all KZN patients given the diagnosis of MS were reviewed to confirm the diagnosis. All patients were contacted telephonically over a period of one month (July 2005) to determine whether they were still alive and still resident in KZN. Clinical, laboratory and treatment data were also extracted from the charts. Results The crude period prevalence per 100 000 for whites was 25.63, for Indians 7.59, people of mixed ancestry 1.94 and for blacks 0.22. The corresponding age standardized prevalence per 100000 were 25.64, 7.15, 1.72 and 0.23, respectively. The clinical features were similar to that seen in the Western world. Up to half of the 167 patients had significant motor disability and optic neuritis was seen in 43/167 (25.7%) of patients. Whilst all traceable MRI brain scans showed some abnormality, 96/139 (69.1 %) met three of the four McDonald's MRI criteria. CSF oligoclonal bands were present in 102 of 124 (82.3%) samples tested. Conclusion MS in KZN is more frequent than previously believed and occurs in all racial groups being most frequent in whites followed by Indians. MS, although rare, does occur in blacks. The increased prevalence figures may reflect better case ascertainment and use of modern diagnostic techniques. However, an absolute increase in numbers cannot be excluded.