As authorities put in place an action plan to prevent the spread of Ebola in the United States, a core assumption of the strategy is now being questioned: whether the 21-day quarantine period is long enough to guarantee that someone exposed to the disease is not contagious.
One expert in the study of biological pathogens says there's not enough evidence to prove the virus cannot be passed along if someone doesn't present symptoms within 21 days.
"Twenty-one days has been regarded as the appropriate quarantine period for holding individuals potentially exposed to the Ebola virus to reduce the risk of contagion, but there does not appear to be a systemic discussion for the basis of this period," Dr. Charles Haas, a microbiology threat researcher at Drexel University, told the
Huffington Post.
"The risk is certainly not zero of anyone beyond 21 days converting to symptomatic," he said.
The Centers for Disease Control and Prevention, however, has mandated a 21-day quarantine period for anyone who may have been exposed to the virus, including the family of Thomas Eric Duncan who arrived from Liberia and died Oct. 8. He was the first person to die of the disease in the United States.
Haas published a paper this week in the journal PLOS Currents: Outbreaks, where he sites data from Ebola outbreaks in Zaire in 1976 and Uganda in 2000 suggesting that there could be up to a 12 percent chance that someone could present symptoms of Ebola after 21 days.
The findings will raise doubts about the government's guidelines for those exposed to the virus, and the effectiveness in preventing its spread. There is no extensive data available, Haas said, and authorities cannot determine with certainty how long the virus remains dormant in the body.
According to the
National Journal, the World Health Organization has recorded cases in which a person has contracted Ebola 30 days after exposure.
Meanwhile, a paper published in the New England Journal of Medicine found that "approximately 95 percent" of patients who had contracted Ebola showed symptoms within 21 days of exposure,
The Washington Post reported.
"There is no quarantine time that will provide absolute assurance of no residual risk from contagion," Haas said in his paper, according to the Journal.
Haas said that more discussion needs to take place to determine whether the 21-day guideline should be revised.
"While the 21 day quarantine value currently used may have arose from reasonable interpretation of early outbreak data, this work suggests a reconsideration is in order and that 21 days may not be sufficiently protective to public health," his paper concludes, according to the Journal.
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