A recent study on the quarantine period for Ebola virus suggests 21 days in isolation may not be enough. The incubation period for Ebola—time between the point of infection to the onset of symptoms—is two to 21 days, according to the World Health Organization. The CDC advises any individuals who were possibly exposed to the virus should monitor their health and restrict their travels for 21 days. Last week, the federal government announced that passengers arriving from West Africa to the five busiest airports in the U.S. would undergo screening for Ebola. Those who refused could face 21 days in quarantine, a government official said. The dog of Nina Pham, a Dallas nurse who contracted Ebola, is currently spending 21 days in quarantine while health officials monitor for symptoms. The family of Ebola victim Thomas Eric Duncan, whom Pham treated, is being quarantined for 21 days at an undisclosed location. The study, published Tuesday by Drexel University professor Charles Haas, advises reconsideration on the criteria for the quarantine period. “21 days may not be sufficiently protective to public health,” Haas writes in his study, published in PLOS Currents: Outbreaks. Haas researched the incubation period for Ebola in previous outbreaks in Congo, Zaire and Uganda. He found “12 percent of the time, an individual case will have a greater incubation time than 21 days,” according to the study. When looking at data of the 1995 Congo outbreak, Haas found a quarantine period of as high as 31 days is more appropriate. via MSN.