Academic journal article Forum for Applied Research and Public Policy

On the Path of a Pathogen

Academic journal article Forum for Applied Research and Public Policy

On the Path of a Pathogen

Article excerpt

Infectious disease researchers from CDC crack the case of a deadly Ebola outbreak and contain the spread.

Sometimes a woman would clutch his sleeve, crying shrilly: "Doctor, you'll save him, won't you?" But he wasn't there for saving life; he was there to order a sick man's evacuation. How futile was the hatred he saw on faces then! "You haven't a heart!" a woman told him on one occasion. She was wrong; he had one. It saw him through his twenty-hour day, when he hourly watched men dying who were meant to live.

- Albert Camus, The Plague, 1947

On May 6, 1995, the Centers for Disease Control and Prevention (CDC) in Atlanta received an urgent phone call. The call, from a U.S. physician employed by the Chevron Company in Kinshasa, Zaire, now the Democratic Republic of Congo, was routed to the CDC's Special Pathogens Branch (SPB) within the National Center for Infectious Diseases.

The physician had heard rumors from several sources of a fatal, febrile, hemorrhagic disease in the general hospital of Kikwit, a small town about 250 miles east of the capital. According to these rumors, several hundred people were involved in this outbreak, including physicians, nurses, and expatriate missionary nuns from Italy. Biological samples from patients were collected at the request of a Zairian physician who had participated in the medical response to the first large outbreak of Ebola hemorrhagic fever in Yambuku, in northern Zaire, in 1976.

Identifying the Agent

After an incubation of four to 10 days, the onset of Ebola virus is sudden, with fever, headache, myalgia, sore throat, and extreme weakness. Gastrointestinal signs include nausea, vomiting, and profuse diarrhea. Hemorrhagic manifestations occur during the peak of the illness (days five to seven) in fewer than half of the patients and include bleeding from nose, gums, and digestive and genital tracts and hemorrhages from puncture wounds.

A poor prognosis is marked by hemorrhagic signs as well as multiorgan failures. In convalescents, recovery takes several weeks and is sometimes associated with arthritis, conjunctivitis, hearing loss, or swelling of the testes.

The patients' biological samples were hand carried to the Prince Leopold Institute of Tropical Medicine in Antwerp, Belgium, to be tested by Guido van der Groen, who also was involved in the identification of the agent of the 1976 Ebola hemorrhagic fever outbreak.

SPB investigators contacted van der Groen by phone in the middle of the night, because of the time difference, and he confirmed that he had received the human samples from Africa. He also explained that his decommissioned laboratory was no longer capable of safely processing biological samples that might contain hemorrhagic fever agents. The specimens were repacked, according to the rules of international shipment of dangerous goods, and sent the following Monday, May 8, by express mail to Atlanta.

At the time, two viruses capable of human-to-human transmission of hemorrhagic fever were known to occur in Zaire: the Crimean-Congo hemorrhagic fever virus first isolated in Kisangani in 1956, and the Ebola virus, which caused the large outbreak in Yambuku in 1976. Ebola was also linked to an isolated case in Tandala in 1977. On May 9, the specimens arrived in Atlanta and the contents were inventoried in accordance with procedure for these suspected pathogens in a biosafety level (BSL)-3 laboratory.(1) Then the specimens were transferred to the CDC's BSL-4 laboratory for processing.

The SPB laboratory does not rely on one but on a panel of different tests for identification of unknown infectious agents. Inside the BSL-4 laboratory, the package was further inventoried: each tube was catalogued, each label was carefully consigned, and each specimen was divided into several samples. Scientists, using cell cultures, attempted to isolate the virus in the BSL-4 laboratory. …

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