Ebola Zaire Outbreaks

1972. Retrospective Serologic Identification

In February 1977, serum from medical personnel who could have come in contact with Ebola were tested for Ebola antibodies. The serum from a Tandala Hospital physician tested positive. In May of 1972, this physician had lacerated his finger while performing an autopsy on a Zairois bible school student. The student died of a hemorrhagic illness that was clinically diagnosed as yellow fever. The physician became ill 12 days after lacerating his finger. In 1977, his hospital records were reviewed, and his symptoms were characteristic of Ebola Hemorrhagic Fever.
- Heymann, D.L. et al. "Ebola Hemorrhagic Fever: Tandala, Zaire, 1977-1978." Journal of Infectious Diseases. Vol. 142. No. 3. September 1980. 372-376.

1976. Yambuku, Zaire.

EBO-Z surfaced shortly after the first Ebola outbreak in Sudan and killed 280 of the 318 people it infected. On September 1, 1976, four days after returning from a tour of northern Zaire, the index case, a 44 year-old male teacher at the Mission School, sought medical intervention for a febrile illness he thought to be malaria. He received a parenteral injection of chloroquine (an anti-malaria drug) from Yambuku Mission Hospital (YMH). YMH did not use disposable needles or sterilize the needles between uses. Parenteral injection was the primary mode of administering nearly all medicines, and Ebola-Zaire (EBO-Z) was quickly disseminated into the surrounding villages serviced by YMH. After 11 of its 17 staff members fell ill with EHF, YMH closed on September 30, 1976, 29 days after the index case received his injection of chloroquine. The WHO International Commission was formed on October 18th, and research teams were mobilized on October 30th. The last case of EBO-Z died on November 5, 1976. Transmission of Ebola during this outbreak occurred mainly through the use of contaminated needles to administer medicine.
- International Commission. "Ebola haemorrhagic fever in Zaire, 1976." Bulletin of the World Health Organization, 56 (2):271-293 (1978).

1977. Tandala, Zaire.

In June of 1977, a 9 year-old girl with a 3 day history of fever, abdominal pain, and hematemesis (the vomiting of blood) was admitted to Tandala Mission Hospital. Prior to her admission to the hospital, she lived with her family in a small village, Bonduni, 20 km from the mission was in good health and had not traveled outside of the Bonduni area. When she was admitted to the hospital, she had a 39.5°C body temperature (normal body temperature is 37°C) and after physical examination, she had a clinical diagnosis of hemorrhagic fever. 28 hours after admission to the Tandala Mission Hospital, she lost consciousness and died. None of her family members tested positive for Ebola antibodies.
- Heymann, D.L. et al. "Ebola Hemorrhagic Fever: Tandala, Zaire, 1977-78." Journal of Infectious Diseases. Vol. 142. No. 3. September 1990. 372-376.

1994. Minkebe and Makokou, Gabon.

This epidemic began in December 1994 and had two different waves of patients (December 1994 and January-February 1995).

First Wave, December 1994
All of the cases in were from 3 gold-panning encampments (Andock, Mékouka, and Minkébé) located in small forest clearings (2000-3000m²) bordering the rain forest. This region of Gabon is sparsely populated; a total of 350 people live in these three villages (20 in Andock, 30 in Mékouka, and 300 in Minkébé). 32 people from the 3 forest encampments contracted EHF (4 from Andock, 23 from Mékouka, and 5 from Minkébé) and traveled 100 km south via boat to Mekouka General Hospital for medical treatment.

Second Wave, End of December 1994 to February 1995
The patients that comprised the "second wave" were secondary or tertiary cases from the first wave and did not originate from the encampments. The first case in the second wave, end of December 1994, was from a small village near Makokou that was far from the encampments, Mayela. This person lived near a traditional healer, "nganga," and probably was infected from contact with a hospitalized patient who sought the medical help of a nganga. In mid January, 16 additional cases occurred near the road that runs south towards Fanceville (one case at Makokou General Hospital, 12 cases from Mayela, one case from Ekatiabe, and two cases from Ekobakoba). None of these 16 patients had been in the area affected by the first wave of the EBO epidemic in Gabon (Mékouka, Andock, and Minkébé) during the previous three months. All 16 patients had been either in direct contact with ill relatives (patients hospitalized at Makokou General Hospital or sleeping in the nganga's home) or with people caring for patients. The last reported case occurred at Ekobakoba on February 9, 1995 and was infected with Ebola while caring for an ill relative at Makokou General Hospital. The Gabonese health officials declared the epidemic officially over on 17 February 1995. The Gabonese authorities declared the epidemic over only eight days after the last case, leaving time for additional infections to occur. In previous Ebola outbreaks, an outbreak was not declared over until a period of 42 days (twice the longest incubation period) has lapsed since the last known infection.

Overall, 49 people were admitted to Makokou General Hospital with suspected HF between December 1994 and February 1995 during these two waves. 29 of the 49 patients had fatal cases of EHF (case fatality rate of 59%). 26 of the EHF patients were male and 23 were female. The mean age of the patients was 37. Whether the number of infected people reflects the true number of EHF cases during this epidemic is not known. Some of the patients who were admitted with suspected EHF could have had a different type of HF or a different disease all together. Some cases who did have EHF could have sought the care of a nganga without seeking hospital care or could have died in their village or in the bush without the EHF investigative team being informed.

The exact origin of the virus during this epidemic is unknown. During this outbreak, there was more than one point of contact with Ebola. This led to a longer duration of the epidemic than if there was only one point of contact with Ebola (as in the Spring 1996 outbreak; see below).

References:
- Georges, Alain-Jean, et al. "Ebola Hemorrhagic Fever Outbreaks in Gabon, 1994-1997: Epidemiologic and Health Control Issues." Journal of Infectious Diseases. 1999; 179 (Suppl 1):S65-75

1995. Kikwit, Zaire.

Image supplied by the World Health Organization.

Image from Outbreak

On January 6, 1995 the first EHF case-patient, "GM", had the onset of illness and was admitted to Kikwit General Hospital. He was a 42-year-old male charcoal worker, a Seventh-Day Adventist and had not eaten monkey meat or been in detectable contact with another EHF case-patient prior to becoming ill with EHF (1, 10). His charcoal plot was on the edge of a dense forest and under a dense forest canopy. During his woodcutting forays and charcoal burning pit diggings, he was exposed to a wide array of possible vectors and, presumably, the natural reservoir (1). He directly, fatally infected at least three members of his family and an additional 10 members of his extended family over a period of 9 weeks and an area encompassing Kikwit and three surrounding villages. Some of the ill people from this family and secondary and tertiary cases in other families who provided nursing care or who had participated in the ritual burials of GM's family went to Kikwit II Maternity Hospital (10).

On April 9, a 36 year-old male laboratory technician who worked at Kikwit II Maternity Hospital went to the Kikwit General Hospital, Zaire because of fever and bloody diarrhea. Suspecting a perforated bowel from typhoid, he underwent surgery on April 10 and 11 (10). He died four days after the onset of symptoms. On April 14, the medical personnel who cared for the laboratory worker in the operating theater or hospital wards became ill with fever, headache, back, joint, and muscle aches, extreme asthenia (clinical definition for physical weakness), and, in some cases, hemorrhagic manifestations. Over 70% of the first generation cases were hospital personnel. One of the ill people who had provided care for the laboratory technician was transferred to a hospital in Mosango (75 miles west of Kikwit). Some of the people who had provided care for this individual developed similar symptoms on approximately April 20 . 10 days after the first-generation cases, a second generation of cases occurred among family and friends of the first-generation cases. Transmission during this outbreak was mainly person-to-person through contact with bodily fluids and ritual cleansing of bodies before burial (usually performed by women). To limit the spread of EHF, the Zairian government closed all schools in Kikwit. The Kinshasa airport remained open during most of the outbreak (5, 7, 8).

The unusual nature of the laboratory technician's death and the medical personnel who cared for him prompted a local ad hoc committee to meet to discuss the nature of these deaths. J.J. Muyembe-Tamfun, Ministry of Health, Zaire, who had participated in the follow-up of the 1976 outbreak of Ebola-Zaire in Zaire (for information about that outbreak, please see 1976 Zaire above) suggested that these illnesses may be caused by a viral hemorrhagic fever. On his prompting, specimens were obtained for analysis and were sent to the Institute of Tropical Medicine, Antwerp, Belgium on May 4th. On May 9th the CDC received portions of these samples for confirmational diagnostic analysis. The CDC confirmed EBO as the etiologic agent responsible for the disease in all 14 patients (the index patient and the medical personnel who subsequently contracted it nosocomially from him) (10).

Based on the preliminary findings of the Institute for Tropical Medicine, on May 6, 1995, the Zairian government sought the assistance of the CDC with an outbreak of a viral hemorrhagic fever (VHF)-like illness that was occurring in Kikwit, Zaire. The population of Zaire in 1995 was approximately 400,000. Kikwit is located approximately 240 miles east of Kinshasa. The CDC's and the WHO's investigation of this outbreak was primarily retrospective (6).

Four separate hospitals were implicated in the outbreak. The first hospital and the center of the outbreak was Kikwit General Hospital (the hospital that treated the laboratory technician). The second was Kikwit II Hospital. The third was the hospital in Mosango, where one of the medical personnel who cared for the laboratory technician was transferred. The fourth hospital was in Yassa Bonga, approximately 250 km. from Kikwit (8).

Image from Khan et al. (10)
The last identified case of EHF during this outbreak was a 27-year-old housewife from Nzinda, Kikwit. She was admitted to Kikwit II Maternity Hospital on 24 June 1995 for the management of a septic abortion. She was discharged on July 14 and died at home on July 16 (10). On August 24, 1995, the 1995 outbreak was declared over, twice the maximum known incubation period (42 days, 21x2) lapsed without any new cases of EHF(1).

More than 1400 samples of different fauna were collected for reservoir testing (4).

Overall, there were 315 cases, 244 of which were fatal (77% case fatality rate). 166 cases were female and 149 were male. 123 female cases were fatal (74% fatal) and 121 male cases were fatal (81% fatal). The cases of EHF ranged from three days to 71 years, with a mean age of 35 years. 26 of the EHF cases were less than 17 years old and 13 were over 60. Median age of the survivors was 29 years; median age of the fatal cases was 35 years. Of the 286 cases where the professional occupations were known, 90 (32%) were health care workers and 61 (21%) were housewives (usually nursed sick or performed the ritual cleansing and burial preparation practices for dead family members). Approximately 73% of the first 70 patients in the epidemic were medical personnel, and the case fatality rate among them was high (1, 6, 9).

266 of the EHF cases were reported to have lived in Kikwit North and South Zones de Sante, the remaining in the Zones de Sante of Bulungu (13 cases), Feshi (1), Gungu (4), Idiofa (1), Mosango (23), Mokala (1), and Vanga (6). All of the cases of EHF were in the Kikwit and Kwilu administrative Sub-Regions, except for 1 case in the Kwango Sub-Region, Bandundu Region. None of the cases were acquired outside of the Bandundu Region (1).

References:
1. WHO Ebola Update August 24, 1995
2. Sanchez, A. et al. Reemergence of Ebola Virus in Africa. Emerging Infectious Diseases 1995:1(3)
3. Clancy, Jim. Fear among us: Deadly Ebola virus lurks in the shadows. CNN October 18, 1995.
4. Rybicki, Ed. "Ebola:comments by C.J. Peters. Source: Report on VTH INTERNATIONAL CONGRESS ON THE IMPACT OF VIRAL DISEASES ON THE DEVELOPING WORLD, South Africa." PROMED. 21 August 1995.
5. Musong, M. et al. "Outbreak of Ebola Viral Hemorrhagic Fever--Zaire, 1995." Morbidity and Mortality Weekly Report. Vol. 44, No. 19. 19 May 1995. 381-382.
6. Musong, M. et al. "Update: Outbreak of Ebola Viral Hemorrhagic Fever--Zaire, 1995." Morbidity and Mortality Weekly Report. Vol. 44, No. 25. 30 June 1995. 468-69, 479.
7. Muyembe, T. et al. "Ebola haemorrhagic fever in Kikwit, Zaire." The Lancet. Vol. 345. 3 June 1995. 1448.
8. WHO. "WHO Press Release: WHO Team in Zaire Sends First Report on Ebola Virus Outbreak." WHO Press Release WHA/11. 11 May 1995.
9. WHO. "WHO Team in Zaire Reports Further Rise in Ebola Cases." Press Release WHO/33. 17 May 1995.
10. Khan, Ali et al. "The Reemergence of Ebola Hemorrhagic Fever, Democratic Republic of the Congo, 1995." Journal of Infectious Diseases. 1999; 179 (Suppl 1):S65-75

1996. Mayibout, Gabon.

Geographic Distribution of 3 Ebola Outbreaks in Gabon. Image taken from: Marie-Claude Georges-Courbot, et al. "Isolation and Phylogenetic Characterization of Ebola Viruses Causing Different Outbreaks in Gabon." EID 1997: 3(1).
Bernard Massika and his wife with ill son (AP Photo).

On January 24, two men butchered a dead chimpanzee they found dead in the forest. On February 5-6, 19 original cases showed signs of EHF (high fever, bloody diarrhea, and severely reddened eyes) and were admitted to Makokou provincial hospital. The average age of the 19 original patients was 18 years. Rapid identification and the implementation of appropriate control measures brought the outbreak quickly under control and prevented further amplification. The last case of EHF died on 12 March 1996. Outbreak officially declared over by the WHO (World Health Organization) on 23 April 1996; 42 days (twice the incubation period) after the last EHF patient death. Total number of EHF cases was 37 (17 females, 20 males), and the mean age of the EHF patients was 27 years (range seven months to 70 years).

References:
- Ebola virus kills 13 in Gabon. CNN February 20, 1996
- Press Release WHO 16 February 1996. Medical Team Investigates Outbreak of Suspected Ebola Haemorrhagic Fever in Gabon
- Marie-Claude Georges-Courbot, et al. "Isolation and Phylogenetic Characterization of Ebola Viruses Causing Different Outbreaks in Gabon." EID 1997: 3(1).
- Garrett, Laurie. "Killer virus strikes Africa for the third time in a year/ Killer Virus Strikes in Gabon." Newsday. 17 February 1996. A07
- "Ebola Haemorrhagic Fever in Gabon." WHO Press Release 19 February 1996.
- "WHO: Disease Outbreaks Reported. Ebola Haemorrhagic fever in Gabon- Update 3. 26 April 1996."
- Georges, Alain-Jean et al. "Ebola Hemorrhagic Fever Outbreaks in Gabon, 1994-1997: Epidemiologic and Health Control Issues." Journal of Infectious Diseases. 1999; 179 (Suppl 1):S65-75

1996. Booué, Gabon and Johannesburg, South Africa (transported).

Outbreak in Booué
First case occurred on 23 July 1996 in Booué. The index case was a 39-year-old hunter who lived in a forest camp in the Booué area. He died on August 7. The second case was a close friend of the index case and died in August. The third and the fourth cases of EHF (also fatal) occurred in late September and were in a traditional healer and his assistant who treated the healer. During the beginning of the outbreak, a dead chimpanzee was found in the forest and tested positive for Ebola. On October 18, three of four new cases were in children who had been in close contact with previous EHF cases. Some patients were transported to Libreville for treatment. The outbreak was brought under control by the international team by 13 November 1996. Last patient died on 18 January 1997. A total of 60 EHF cases, of which 45 were fatal (75% mortality rate). Booué area: 44 cases, including 33 deaths. Libreville: 14 cases, including 10 deaths. No documented secondary transmission. Lambarene: one fatal case. WHO officially declared this outbreak over on 2 March 1997.

Transport from Libreville to Johannesburg
On October 27, a 40 year-old Gabonese doctor infected with Ebola in Libreville from a patient who was linked to the Booué outbreak flew to Johannesburg, South Africa for treatment. The patient who transmitted EBO to the male physician died on 5 November 1996. The physician was accompanied on a commercial plane to South Africa by a nurse. He arrived to the Morningside Medi Clinic with a diagnosis of rhabdomyolysis (a clinical and biochemical syndrome resulting from an injury which damages the integrity of the sarcolemma of skeletal muscle, leading to the release of potentially toxic muscle cell components into the circulation). He had swinging temperatures of 42°C (normal body temperature is 37°C, was very ill, and had signs of hepatitis. During the course of his treatment, a muscle biopsy was performed (presumably to test for rhabdomyolysis). At the 300 bed hospital in Libreville, he worked as a "resuscitator." On October 19, he developed a febrile illness, which he treated with antimalarial drugs. Two to three days later, he developed a high fever and diarrhea. He was not aware that any of the patients he treated had Ebola. He recovered from EHF and returned home to Gabon on November 20. Mrs. Marilyn Lahana, a 46-year-old theater/anesthesia nursing sister, treated the Gabonese physician at Morningside Clinic, Johannesburg and became infected nosocomially with Ebola from the Gabonese physician. She was exposed to his blood while performing a procedure for placing a central line on him. She was exposed to a great deal of blood when she cleaned up after the procedure. She became ill (slight fever) on November 2. She developed a severe headache on November 6 and was admitted to Sandton Medi Clinic with suspected encephalitis. On admission to the hospital, she had a moderately low platelet count (105x10E9/L). Suspecting a bacterial infection, she was placed on antibiotics. Over the next few days after being admitted to the hospital, she developed a fine confluent macular rash and diarrhea, which was attributed to a possible reaction to the antibiotics. By November 9, her platelet count fell from 105 to 37, had marked leukopenia, and had elevated AST and ALT levels (her liver transaminase levels were initially normal). On November 9, suspecting viral hemorrhagic fever (low platelets, rash, and fever), her blood was submitted for analysis. On November 14, her blood tested positive for Ebola. Mrs. Lahana had developed hematemesis (bloody vomit), high AST and ALT levels (general liver function test), and slightly elevated leukocyte counts by November 14. November 16, she was moved to Johannesburg Hospital where strict barrier-nursing care was implemented. She died on November 24 from a brain hemorrhage.

References:

*Due to the fact that these outbreaks occurred before Zaire was changed to the Democratic Republic of the Congo, the country that is currently known as the Democratic Republic of the Congo is referred to as Zaire.

©1999 Tara Waterman