The Ebola epidemic still ravaging West Africa has sickened an estimated 26,000 people so far. More than 10,800 of these people have died. A new study points to why caring for these dead can be dangerous: Their corpses remain infectious for 7 days.
That’s the suspicion, anyway. The new study was not conducted with dead people. Instead, researchers studied macaques that took part in Ebola research. All five monkeys had been quite sick. At death, their bodies hosted high levels of the virus.
Researchers at a National Institutes of Health lab in Hamilton, Mont., wanted to know how long the animals’ carcasses would remain infectious. So they treated them much as burial teams in Africa typically treat the bodies of loved ones. They were covered. They were not embalmed. Their temperatures were kept similar to what corpses in villages might encounter.
The researchers swabbed the animals and sampled their internal organs and blood. They did this for up to 10 weeks. They were scouting for “live” virus. (Viruses aren’t really alive. This term instead refers to the fact that the germ is still able to infect another organism.)
The animals’ skin and blood remained infectious for at least 7 days. Internal organs hosted live virus for up to 3 days. “It is unlikely that viable virus persisted for longer than we measured,” report Joseph Prescott and his team. Their findings appear in the May 2015 issue of Emerging Infectious Diseases.
The bodies of people who died from Ebola often host high levels of virus . This suggests “that most fresh corpses contain high levels of infectious virus, similar to the macaques in this study,” the researchers say.
Weeks after the virus was no longer infectious, the researchers could still detect it inside the animals’ bodies. They did this by looking for RNA. RNA is a type of genetic material carried by many viruses, including the Ebola virus. Researchers can use that RNA to identify which, if any, viruses are present. In the macaques, Ebola RNA remained easily detectable in samples taken from the mouth and blood for at least 3 weeks. Elsewhere in the body, RNA often was detectable for up to 10 weeks.
This suggests RNA can be used to confirm Ebola — in wildlife and in human corpses — weeks after death. This would include periods long after corpses could spread disease. That could be very helpful, since it would allow researchers to sample animal carcasses in the wild (or in markets). That testing could show whether the animal might have had some role in kick-starting a human epidemic. It also could help scientists identify carcasses of animals that might have succumbed to the disease. (For instance, a large share of wild gorillas appear to have died from Ebola in recent years.)
The new data help explain why the disease spread so easily in the early weeks of the epidemic in West Africa. After a person died of Ebola, family members came to wash the bodies of their dead. They often touch that person one last time. Such hand contact could transmit the virus.
The new data also highlight the risks of eating bush meat. That is meat that comes from wild animals, such as bats, monkeys and deer. Many of these animals can host Ebola or other diseases. Studies have shown that many of the animals sold as bush meat were infected at the time they died. People who clean or prepare those animals for cooking might also become infected.
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bush meat Wild mammals eaten by people, including not only cats, Chinese bamboo rats, squirrels, badgers and civets but also primates, such as monkeys, chimps and gorillas.
carcass The body of a dead animal.
corpse The body of a dead human.
Ebola A family of viruses that cause a deadly disease in people. All cases have originated in Africa. Its symptoms include headaches, fever, muscle pain and extensive bleeding. The infection spreads from person to person (or animal to some person) through contact with infected body fluids. The disease gets its name from where the infection was first discovered in 1976 — communities near the Ebola River in what was then known as Zaire (and is now the Democratic Republic of Congo).
epidemic A widespread outbreak of an infectious disease that sickens many people (or other organisms) in a community at the same time.
genetic Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.
infectious An adjective that describes a type of germ that can be transmitted to people, animals or other living things.
National Institutes of Health, or NIH This is the largest biomedical research organization in the world. A part of the U.S. government, it consists of 21 separate institutes — such as the National Cancer Institute and the National Human Genome Research Institute — and six additional centers. Most are located on a 300 acre facility in Bethesda, Md., a campus containing 75 buildings. The institutes employ nearly 6,000 scientists and provide research funding to more than 300,000 additional researchers working at more than 2,500 other institutions around the world.
RNA A molecule that helps “read” the genetic information contained in DNA. A cell’s molecular machinery reads DNA to create RNA, and then reads RNA to create proteins.
viable (in biology) Able to survive and/or live a normal lifespan. (in engineering) Something that should work or operate according to plan, as in a “viable concept.”
virus Tiny infectious particles consisting of RNA or DNA surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact no virus is truly alive. It doesn’t eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.
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Original Journal Source: J. Prescott et al. Post-mortem stability of Ebola virus. Emerging Infectious Diseases. Vol. 21, May 2015. doi: 10.3201/eid2105.150041.