The Ebola virus can be found across the animal kingdom, from bats and birds to pigs and porcupines. But there is a difference between having a disease and transmitting it to another animal—or another species. That’s at the heart of a controversial move by Spanish health authorities, who have obtained a court order to euthanize the dog belonging to a nurse who contracted the Ebola virus in Madrid, saying that available scientific knowledge suggests dogs can transmit the virus to humans. But how much do we know about which animals can catch and transmit the deadly virus?
Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention (CDC), said in a news conference on Tuesday that “we know in rural areas of Africa, Ebola can infect mammals. In fact, that’s how it spreads, from probably bats to animals living in the forest, people hunting the animals.” Ebola has to date been found in many bush animals, including bush pigs, rodents, porcupines and forest-dwelling antelope. Any infected carcasses could spread the virus to hunters or to anyone who eats bush meat.
To date, there is no documented case of Ebola spreading to people from dogs or dogs to people, and only one study, carried out by the CDC, looks at whether dogs can get Ebola at all. This research into the prevalence of Ebola-virus antibodies in dogs from regions of Gabon affected by the 2001–2002 outbreak showed that “dogs can be infected by Ebola virus” but exhibit no symptoms and the infection eventually clears.
The researchers concluded that “dogs could be a potential source of human Ebola outbreaks and of virus spread during human outbreaks,” but they did not test their hypothesis that human infection could occur through licking, biting or grooming. Instead, the study assumed dogs would transmit the infection in the same way as other animals observed in experiments; those animals excreted viral particles (in saliva, urine, feces) for a short period before the virus was cleared. David Moore, an expert in infectious diseases from the London School of Hygiene and Tropical Medicine, said that since no dogs showed symptoms of the Ebola virus “there is absolutely no evidence to support a role for dogs in transmission.”
The study also suggests that differences in behavior and diet of pet dogs may alter risks in Ebola transmission. Whereas most dogs in Western Europe are fed dog food, many of the dogs studied in Gabon scavenged for their food, eating small dead animals that could have exposed them to the virus.
Both the World Health Organization and recent reports have suggested that the 2014 outbreak of Ebola can be traced to fruit bats in the West Africa region. Guinea, where bat soup is a local delicacy, has reportedly banned the sale and consumption of bat meat since the start of the outbreak.
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