The Ebola virus can live in and on the body of a victim for as long as seven days, researchers reported Thursday in a finding that helps explain the insidious spread of the infection.
Public health experts have long known that touching the body of someone who's died of Ebola is extremely dangerous. The World Health Organization said just this week that handling the bodies of victims — mostly during funeral rites — was fueling the continued spread of the virus in West Africa.
No one's really tested just how long the virus survives, however — in no small part because it wouldn't be acceptable to leave victims unburied to do it.
Vincent Munster and colleagues at Rocky Mountain Laboratories in Montana, part of the National Institutes of Health, did the next best thing. They tested the bodies of monkeys that got fatal doses of Ebola as part of other experiments. The monkeys had been euthanized to prevent suffering but had infections that would have killed them.
"Immediately after euthanasia, multiple samples were collected: oral, nasal, ocular, urogenital, rectal, skin, and blood (pooled in the body cavity) swab samples and tissue biopsy specimens: from the liver, spleen, lung, and muscle," they wrote in their report, published in the journal Emerging Infectious Diseases.
"Carcasses were placed in vented plastic containers in an environmental chamber at 27 degrees C (80 degrees F) and 80 percent relative humidity throughout the study to mimic conditions in West Africa."
They ran various tests and could find evidence of genetic material from the virus for as long as 10 weeks. But this genetic material, called RNA, isn't infectious.
Viruses aren't really "alive" and must hijack a living cell to replicate. As soon as infected cells start to break down, the virus also dies.
But viable, or living, virus survived in tissue and in blood for seven days, the researchers found.
"The highest amount of viral RNA was in oral, nasal, and blood samples," they wrote.
They noted that levels of virus are very high in people who have just died of Ebola and the conditions are likely very similar to the monkeys they studied. "Furthermore, family members exposed to Ebola patients during late stages of disease or who had contact with deceased patients have a high risk for infection," they added.
"Viable virus can persist for at least seven days on surfaces of bodies, confirming that transmission from deceased persons is possible for an extended period after death. These data are also applicable for interpreting samples collected from remains of wildlife infected with Ebola virus, especially nonhuman primates, and to assess risks for handling these carcasses."
Most experts believe that Ebola is transmitted from animals to people who hunt or butcher wild game, called bushmeat. This bushmeat can include primates such as monkeys and apes, who are as susceptible to Ebola as humans are.
Ebola has infected 22,000 people in Guinea, Sierra Leone and Liberia and killed more than 9,000, according to the World Health Organization. WHO says until everyone in those three countries can be persuaded to stop having direct contact with Ebola patients and victims, the virus will continue its spread.
Ebola virus doesn't live long outside a victim's body, and, unlike measles virus, doesn't travel in the air. People must have direct contact with a victim's bodily fluids, such as blood or feces, to become infected.