Ebola outbreaks of 1976

Epidemics

Date: Late June-November 20, 1976, in Sudan and September 1-October 24, 1976, in Zaire

Place: Southern Sudan and northern Zaire (now Democratic Republic of Congo)

Result: 151 dead out of 284 cases (53 percent mortality), 280 dead out of 318 cases (88 percent mortality)

In 1967, 23 commercial laboratory workers were hospitalized in Marburg, Germany, for a hemorrhagic fever that was traced to the handling of vervets (African green monkeys) imported from Uganda. Six more medical workers in Frankfurt, Germany, who were involved in the treatment of these patients, also became sick. At the same time, a veterinarian who handled monkeys and his wife were infected in Belgrade, Yugoslavia. Electron microscopy work determined that the disease agent was an unusual-looking ribonucleic acid virus. It had a unique, slender filamentous comma shape or branched shape and caused 23 percent mortality. Relatively few detected recurrences of this disease have occurred since its discovery. However, a serologically distinct but related virus with similar effects, now known as Ebola hemorrhagic fever (EHF), was identified during two almost simultaneous epidemics during 1976.

The diseases begin four to sixteen days after infection as an increasingly severe influenza-like illness, with high fever, headaches, chest pains, and weakness for about two days. This is followed in the majority of cases by severe diarrhea, vomiting, dry throat, cough, and rash. Bleeding from body openings is very common, and patients can become aggressive and difficult to manage. The virus reaches high levels in the blood and other body fluids, and the resulting tissue infections are so extensive that organ damage can be widespread. Within seven to ten days the patient is severely exhausted and dehydrated and often dies of shock. The natural animal reservoir for this virus is not known, and human-to-human transmission mostly results from close, intimate contact. There is presently no known treatment.

Sudan. The epidemic started in Nzara township, where most residents live in mud-walled, thatched-roof houses in the thick woodlands adjacent to the African rain forest zone. The first persons infected with Ebola hemorrhagic fever are believed to be three employees of a cotton factory, part of an agricultural cooperative, in Nzara; local raw cotton is converted to cloth by the 455 employees of this factory. A factory storekeeper became ill on June 27, 1976, with a high fever, headache, and chest pains. He bled from the nose and mouth and had bloody diarrhea by the fifth day, was hospitalized in Nzara on June 30, and died on July 6. His brother nursed him and also became sick but recovered after two weeks.

Another storekeeper who worked with the deceased storekeeper entered the hospital on July 12 and died July 14. His wife took ill and died on July 19. Another factory worker employed in the cloth room next to the store where the two deceased employees worked became sick on July 18, entered the hospital on July 24, and died on July 27. None of the men lived near each other nor socialized together, and their lives were very different. Eventually associates of the third employee became ill, and one individual who managed the jazz club, a social center in Nzara, journeyed to the Maridi hospital, where he died. Forty-eight cases and 27 deaths in Nzara could be traced to the third employee. By July, September, and October, additional factory employees were getting sick but could not be tied directly to previously infected individuals. Most were cared for by family members in isolated homesteads. This helped limit the spread of the disease.

The individual who died in Maridi was cared for by close friends and several hospital employees, all of whom came down with the fever. They were cared for by others, who managed to spread the disease to various regions around the Maridi township. An additional source of infection arrived when a nurse from Nzara came in for treatment. Many of the hospital staff were also infected.

By the time the World Health Organization (WHO) team arrived in Maridi on October 29, the situation was dire there but improving in Nzara. The Maridi hospital was virtually emptied of patients; 33 of the 61 on the nursing staff had died, and 1 doctor had developed the disease. Eight additional people associated with hospital maintenance also died. Thus, the local community viewed the hospital as the source of their woes. Isolation measures were quickly adopted, and protective clothing was distributed within the hospital.

Five teams of 7 individuals each, including schoolteachers and older school boys led by a public health official, were to visit every homestead and identify infected individuals in the community, who were then requested to come to the hospital. If they preferred to stay at home, relatives were warned to restrict contact with the patient. Funeral rituals also hastened the spread of the disease because ritual called for the body being prepared for burial by removing all food and excreta by hand. Local leaders were apprised of the situation, and they encouraged people to bring their dead to Maridi, where medical personnel would cleanse the bodies. Their support accelerated the work of the surveillance teams, which expanded their efforts to include a 30-mile radius around Maridi by November 17.

The final count of 284 cases was distributed as 67 in Nzara, 213 in Maridi, 3 in Tembura, and 1 in Juba. Epidemiological analysis indicated that Nzara was the source of the epidemic, and the cotton factory was studied most intensively. Infections developed in the cloth room and nearby store, the weaving areas, and the drawing-in areas only. There were no infections in the spinning area, where most of the employees worked.

Zaire. The focus of the epidemic in Zaire was in a region where more than three-quarters of the 275,000 people of the Bumba zone live in villages with fewer than 5,000 people. This region is part of the middle Congo River basin and is largely a tropical rain forest. The Yambuku Catholic Mission was founded by Belgian missionaries in 1935 and provided medicines to a region of about 60,000 people in the Yandongi collectivity (county). In 1976 there were 120 beds supervised by a medical staff of seventeen, including a Zairean medical assistant and three Belgian nuns who worked as nurses and midwives. Around 6,000 to 12,000 people were treated monthly. Five syringes and needles were distributed to the nursing staff every morning for use at the outpatient, prenatal, and inpatient clinics. Unfortunately, they were only rinsed in warm water between uses, unlike in the surgical ward, which had its own equipment that was sterilized after every use.

The first person to exhibit definitive signs of the Ebola virus was a forty-four-year-old male teacher at the Mission School who had recently toured the most northern areas of Zaire, the Mobayi-Mbongo zone, by automobile with other Mission employees from August 10 to August 22. His fever was suggestive of malaria, so he was injected with chloroquine on August 26 at the outpatient clinic. His fever disappeared and then reappeared on September 1, along with other symptoms. He was admitted with gastrointestinal bleeding to the Yambuku Mission Hospital (YMH) on September 5. The medical staff gave him antibiotics, chloroquine, vitamins, and intravenous fluids but nothing worked. He died on September 8.

Records for the outpatient clinic were too incomplete to trace easily possible earlier cases, but there may have been one individual with EHF treated on August 28, who was described as having an odd combination of symptoms: nosebleeds and diarrhea. He may have been the source of the infection, but he left the clinic and was never found. Nine additional conclusive cases occurred in people who had received treatment for other diseases at the outpatient clinic at YMH. A sixteen-year-old female was given transfusions for her anemia. An adult woman was given vitamin injections so that she could care for her husband recovering from hernia surgery. Another adult woman was recovering from malaria, tended by her husband. All later succumbed and died of EHF, and soon those who had nursed these individuals or prepared their bodies for burial also came down with the disease. The disease struck 21 family members and friends of the first patient, and 18 died.

This new, mysterious disease that caused people to bleed to death and to go crazy was soon causing a panic in the local villages. On September 12 a nun became sick, and other nuns radioed for help. The provincial physician arrived on September 15 and, equally baffled, gathered as much information as he could and then returned to Bumba, where he requested help from administrators in Kinshasa. On September 19, the nun died; by then, the bleeding illness was responsible for deaths in more than 40 villages.

Two professors of epidemiology and microbiology from the National University of Zaire were sent to Yambuku. They arrived on September 23, expecting to study the situation for six days, but left after a day of collecting blood and tissue samples from cadavers and patients. The professors also took two nuns and a father back with them to Kinshasa for treatment. Thirteen of the 17 staff members at YMH had become infected and 11 had died, so the hospital was closed on October 3. At least 85 out of 288 cases, where transmission could be traced, had received injections at YMH. Another 149 patients had had close contact with infected patients, and 49 had been subject to injections and patient contact.

The former physician of Zairean president Mobutu Sese Seko, Dr. William Close, was contacted by the Minister of Health in order to gain assistance from the United States. He contacted the Centers for Disease Control (CDC) in Atlanta, Georgia, which provided laboratory support. By mid-October medical authorities had imposed a quarantine on the Bumba zone. Village elders requested their community members to stay in their homes, and all activities stopped. By now officials were aware that there was a similar epidemic in southern Sudan, and blood samples from both locales were shipped to the virus unit of the WHO in Geneva, which then forwarded them to the CDC. On October 15, the WHO reported the presence of a new virus, later named Ebola for a local river.

What followed was an internationally coordinated investigation of both Zaire and Sudan by at least eight nations, several international organizations, and Zaire’s entire medical community. The most up-to-date isolation strategies were used, and patients were attended by personnel in protective suits. A complete epidemiological investigation was conducted, studying 550 villages and interviewing 34,000 families. Scientists took blood samples from 442 people in the communities where the infection was most prevalent. They also collected local insects and animals, with no success at finding the animal reservoir.

Although geographically and chronologically close, the two epidemics appear to have been independent events. There were relatively few travelers and no Ebola cases between the two locales. Molecular analyses also indicated the two strains of Ebola were different. The Nzara virus is relatively more infectious, and the Yambuku virus is more lethal. Both Ebola virus strains were placed in the new filovirus family.

It was not until 1995 that another major Ebola epidemic occurred, this time in Kikwit, Zaire. EHF outbreaks before 1995 were sporadic and small, including 1 death in Tandala, Zaire, in 1977; 34 cases and 22 dead in Nzara and Yambio, Zaire, in 1979; and 1 case in Tai, Ivory Coast. There may have been a near miss when macaque monkeys from the Philippines residing in a facility in Reston, Virginia, died from an Ebola-like filovirus in 1989. The virus did not affect humans. Scientists continued to search for a cure, knowing that the prevention of future epidemics hinges on identification of the animal reservoir and the presence of adequate health care facilities in some of the poorest regions of the world.

Bibliography

Garrett, Laurie. The Coming Plague: Newly Emerging Diseases in a World out of Balance. New York: Penguin Books, 1994.

Klenk, Hans-Dieter, ed. Marburg and Ebola Viruses. New York: Springer, 1999.

Murphy, Frederick A., and Clarence J. Peters. “Ebola Virus: Where Does It Come from and Where Is It Going?” In Emerging Infections, edited by Richard M. Krause. San Diego, Calif.: Academic Press, 1998.

Preston, Richard. The Hot Zone. New York: Random House, 1994.

Simpson, D. I. H. Marburg and Ebola Virus Infections: A Guide for Their Diagnosis, Management, and Control. Geneva, Switzerland: World Health Organization, 1977.

Smith, Tara C. Ebola. Philadelphia: Chelsea House, 2006.

WHO/International Study Team. “Ebola Haemorrhagic Fever in Sudan, 1976. Ebola Haemorrhagic Fever in Zaire, 1976.” Bulletin of the World Health Organization 56, no. 2 (1978): 247-293.