Drexel College of Engineering study questions 21-day quarantine for Ebola

Oct. 20, 2014

As medical personnel and public health officials are responding to the first reported cases of Ebola virus in the United States, many of the safety and treatment procedures for treating the virus and preventing its spread are being reexamined. One of the tenets for minimizing the risk of spreading the disease has been a 21-day quarantine period for individuals who might have been exposed to the virus. But a new study by Charles Haas, PhD, a professor in Drexel University’s College of Engineering, suggests that 21 days might not be enough to completely prevent spread of the virus.

Haas’s study, “On the Quarantine Period for Ebola Virus,” recently published in PLOS Currents: Outbreaks questions the basis for our knowledge about the virus, namely previous outbreaks in Africa in 1976 (Zaire) and 2000 (Uganda) as well as the first nine months of the current outbreak.

In all cases, data gathered by the World Health Organization reported a two-to-21 day incubation period for the virus. Haas asserts that with any scientific data of this nature there is a standard deviation in results –a percentage by which they may vary. In the case of Ebola’s incubation period the range of results generated from the Zaire and Uganda data varied little. But in data from other Ebola outbreaks, in Congo in 1995 and recent reports from the outbreak in West Africa, the range of deviation is between 0.1 percent and 12 percent, according to Haas. This means, he suggests, that there could be up to a 12-percent chance that someone could be infected even after the 21-day quarantine has passed with no symptoms.

“While the 21-day quarantine value, currently used, may have arisen from reasonable interpretation of early outbreak data, this work suggests reconsideration is in order and that 21 days might not be sufficiently protective of public health,” Haas says. Read the study.

Read more