Descriptive Epidemiology of Multiple Sclerosis (MS) Multiple Sclerosis.

Descriptive Epidemiology of

Multiple Sclerosis

(MS)

Course of DiseaseAcute - Very Rapid Course, Death in a

few monthsProgressive - Gradually becoming

worse, well defined remissions and exacerbations

Benign - Exacerbations with very long remissions

Subclinical - No Symptoms, identified at autopsy

ProgressiveAcute

Epidemiology: Incidence of MS in

Denmark

0

2

4

6

8

10

10 20 30 40 50 60

MalesFemales

Incidence of MS in Iceland

0

0.5

1

1.5

2

2.5

3

3.5

1900 1910 1920 1930 1940 1950 1960 1970

per

/100

,000

Incidence of MS in Faroe Islands

0

2

4

6

8

10

12

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

NativePost-war birth

Incidence of MS in Faroe Islands by age

0123456

Females

Males

Years since 1942:in Faroe Islands

0

2

4

6

8

per

100

,000

Incidence of MS in South Africa

0

2

4

6

8

10

12

10 20 30 40 50

Immigrants

SA Born AfricanSpeak

SA Born EnglishSpeak

All White SA

Prevalence of MS

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80

Winnipeg

Boston

New Orleans

Unusual Occurrence of MS in

Tropical Island

0

1

2

3

4

5

6

60

62

64

66

68

70

72

74

76

78

80

82

84

Risk Factors:

Unusual Stress in 2 Yrs Before

Cases Controls p value

79% 54% <0.01

Risk factors:

Exposed to Animal Illness

Cases Controls

43% 19%

Risk Factors:

Exposed to Canine Distemper

Cases Control

17% 6%

Physical Activity and MS

Cases ControlsPhysicallyActive

50% 34%

MixedActivities

27% 24%

SedentaryHobbies

20% 36%

None 3% 6%

Immunologic Involvement

Autoantibodies Encephalomyelitis developing--Similar to the administration of rabies virus vaccine

Evidence for a superantigen?

Frequency of Viral Infection

Colds Flu Enteric Herpes

Controls 9% 9% 0% 3%

Cases 5% 2% 8% .03%

Concordance Rates in Twins

MZ DZ

31/107 13/101

0.29 0.13

Prevalence of MS in First Degree

Relatives

Sibs Parents Offspring125/10,682 41/6,521 9/1,521

0.0117 0.0063 0.0059

DZ Risk versus Sibling Risk

DZ Sibling

0.13 0.012

HLA Antigens and MS:

Northern EuropeansCases Controls RR

A3 32 21 1.8

B7 35 18 2.5

DR2 41 22 2.5

ConclusionsMS caused by environmental factors, but not clear what they are

For MS there is evidence for HLA associations, however, there is more than HLA

MS is a multiloci disease