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Patient with Ebola Hemorrhagic Fever, Bumba Zone, Equateur Province, DR Congo (Zaire), October 1976

Active Surveillance for EHF Cases, Equateur Province, DR Congo (Zaire), November-December 1976

Investigations of EHF Cases in Villages, Equateur Province, DR Congo (Zaire), October-December 1976

Dr. M. Mbuyi & Nurse Sukato interviewing mourning family member

Ebola Hemorrhagic Fever in Democratic Republic of the Congo (Zaire), 1976-1977 Selected Events

Aug 26 First patient presents with fever in Yambuku, Equateur Province, receives chloroquine injection; fever resolves in 4 days

Sept 1 EHF begins in first patient

16 Local clinician reviews 17 patients; reports unknown disease to Kinshasa

23-25 First medical team visit from Kinshasa; typhoid feversuspected, vaccination; evacuation of Belgian nun to capital

30 Yambuku hospital closed, 11 of 17 staff members dead

Sept 30/Oct 20 Three nurses die in Kinshasa

Ebola Hemorrhagic Fever in Democratic Republic of the Congo (Zaire), 1976-1977 Selected Events

Oct 2-6 Second medical visit from Kinshasa; specimens

collected

3 Health zone quarantined by Minister

8-12 Transmission occurring in Kinshasa hospital

13-14 Filovirus seen on EM in Belgium, UK and USA

14 New virus (Ebola) identified at CDC

18 International Commission formed

19-27 Survey team to Yambuku; reports active cases

in 8 villages

30 Airlift of surveillance teams to NE DR Congo,

covers DRC-Sudan frontier

Nov 2 Plasmapheresis program begins with

convalescent patients

4 Widespread surveillance in epidemic zone

5 Last case dies

16 Surveillance, research and clinical care

support arrives in Yambuku

Dec 16 Emergency officially over

Jan 28 Plasmapheresis program ends

Selected Events (cont’d)

EHF in DR Congo (Zaire), 1976-1977

Ebola Hemorrhagic Fever in Democratic Republic of the Congo (Zaire), 1976-1977

International Commission Discoveries

Virology

• Isolation and characterization of Ebola virus

• Differentiation from Marburg virus

• Immunology


Clinical

• Described symptoms and signs including

– Hemorrhagic manifestations

– Pancreatitis

• Incubation period


Patient Management and Control


• Isolation of patients effective

• Surveillance of households, villages

• Plasmapheresis of convalescents



Epidemiology

• Mode of transmission

• Risk groups

• Attack rates; individuals, families, villages

• Geographic distribution and spread



Immunology

• Developed IFA test for Ebola

• Found evidence of previous infection



Epidemic in northern DR Congo (Zaire)

• 100% of villages affected

• 100% of persons in villages affected

• 100% of affected persons in villages dead

Initial Information


• Cause?– Typhoid– Lassa fever– Yellow fever

Initial Information

• Sources of Information– International plantation manager (confidential)– World Health Organization (limited)– US Embassy (limited)

– Scientists in Belgium and France

Ebola Hemorrhagic Fever in DR Congo (Zaire), 1976

Risk Factors Associated with Person to Person Spread

Person to Person Family Contacts

(non-infected)

Risk Factor Cases % Yes Cases % Yes P

Touched cases

Attended burial

Cared for case

Slept in same room

Prepared cadaver

Aided in delivery ofchild from sick patient

126

126

119

116

116

104

86

86

71

69

59

18

91

98

84

86

58

74

84

86

71

68

58

9

ns

ns

ns

ns

ns

p<0.001


Distribution of Cases in Villages Cases Number of Villages % of Villages Cumulative %

1

2-5

6-9

10-14

15-19

20-29

30

17

18

12

4

1

1

2

55

31

33

22

7

2

2

4

31

64

86

93

95

97

101

Family Contact Attack Rate by Generation of Illness

Generation

1*

2

3

4

Total

No. of Families of Cases

61

62

18

5

146

No. of Family Exposures

496

459

117

29

1103

No. of Subsequent

Cases

38

20

3

1

62

Attack Rate (%)

7.5

4.4

2.6

3.4

5.6

* persons acquiring disease by injection


Distribution of Ebola Hemorrhagic Fever Cases by Transmission Type, Yambuku, DR Congo (Zaire), 1976

Injection

Person-to-person

Both possible

Unknown

Neonatal

CasesNo.

85

149

43

30

11

318

%

27

47

14

9

3

100

SurvivorsNo.

0

30

4

4

0

38

%

0

79

11

11

0

101

Transmission History


Ebola Hemorrhagic Fever, DR Congo (Zaire), 1977

Case Definitions

Probable:

• Living in epidemic area

• Died after 1 days with 2 of the following:

– headache, fever, abdominal pain, nausea/vomiting,

bleeding

• With 3 preceding weeks received an injection or had

contact with a probable or proven case

• No other diagnosis


Case Definitions

Proven:

• Ebola virus isolated or shown by EM

• Or IFA titer of 1:64 after 3 weeks of symptom onset


Case DefinitionsInfection:

• IFA titer 1:64 with no symptoms/signs August 15-

November 19, 1976

Possible:

• Headache and/or fever for 24 hours with or without other signs/symptoms

• Contact with a probable or proven case, within 3 weeks

• Treated with antimalarials, antibiotics, antipyretics

• Bled and checked for antibodies

• Any case of fever and bleeding anywhere in DR Congo

Neonatal:

• Newborns of probable cases if died within 28 days


Case Definitions

Primary Contact:

• Face to face contact with a probable or proven case

• Between 2 days before symptom onset and death or recovery

• Surveillance 21 days from last contact

Secondary Contact:

• Face to face contact with primary contact

Ebola Hemorrhagic Fever, DR Congo (Zaire), 1976-77

Major Gaps and Challenges

• Natural history undefined

• Surveillance and response weak

• No specific treatment or precaution

• Limited application of modern technologies

• Few laboratories involved

• Filovirus and other “orphan” diseases receive

low priority

Health & Medicine

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