Ebola Imperils Gorilla Species in Congo Republic By DENISE GRADY The Ebola virus killed 3,500 to 5,500 gorillas in one region of the Congo Republic from 2002 to 2005, and its continued spread, along with hunting, could wipe out the species, researchers are reporting today. “A lot of animals are dying,” said Dr. Peter D. Walsh, an ecologist at the Max Planck Institute for Evolutionary Primatology in Leipzig, Germany, and an author of a report being published today in the journal Science. “There’s a massive decline.” Several Ebola vaccines have been developed that work in animals in the lab, including monkeys, and Dr. Walsh is eager to test them on gorillas in the wild, by injecting the animals with darts or putting an oral vaccine in food. By tracking the spread of the virus and vaccinating animals in its path, it may be possible to stop outbreaks, he said. Other researchers say that although vaccination might be feasible, it is not known whether the vaccine could be made into a heat-stable version or an oral form. In addition, there would be miles of red tape to cut through, involving conservation groups, donors and governments. Dr. Stuart Nichol, chief of molecular biology in the special pathogens branch of the Centers for Disease Control and Prevention, said: “It’s really going to be a nightmare to try to press forward with some kind of vaccine approach. On the other hand, it doesn’t feel good to sit back and do nothing. But in reality it’s going to be exceedingly difficult to do anything.” The authors of the report have been studying western gorillas — a species distinct from eastern gorillas — since 1995 in the Lossi Sanctuary in the northwestern Congo Republic, near Gabon. Congo Republic is to the west of the larger nation of Congo, formerly known as Zaire. In 2002, after human disease outbreaks caused by the Zaire strain of the Ebola virus, the researchers began finding dead gorillas. Over a number of months they found 33, tested 12 for Ebola and found that 9 were infected. And from October 2002 to January 2003, 130 of the 143 gorillas they had been studying — 91 percent — disappeared. The losses continued: 91 of 95 gorillas the researchers were watching died from October 2003 to January 2004. Many chimpanzees in the region have also died. In the past, other researchers have questioned whether Ebola was really killing so many apes, since relatively few carcasses had been tested. Dr. Nichol said that he would like to see more testing, but added that he believed the group’s findings, and acknowledged that obtaining samples was difficult and dangerous work. The region is a dense jungle; male gorillas attack humans who venture too close, and carcasses are teeming with the virus and highly infectious. To collect samples, scientists have to wear germproof suits that cover them and filter the air they breathe. Although gorillas are hunted for meat, even in preserves where it is illegal, the authors say there is nowhere near enough hunting in the region they studied to account for so many missing animals. They estimate that between 2002 and 2005, Ebola has killed 3,500 to 5,500 gorillas in a region of about 2,000 square miles — and that figure, they say, is a conservative one. Dr. Walsh said it was his “educated guess” that since 1992, Ebola may have killed as many as a quarter of the world’s gorillas. Apes are humans’ closest relatives, and like people they suffer a brutal illness from Ebola and die from hemorrhage and shock. Precisely how gorillas contract the disease is a mystery. Scientists assume they must catch it from another animal that acts as a natural reservoir host and carries the virus without being killed by it. Fruit-eating bats are suspected, but none have been confirmed as the reservoir, Dr. Nichol said. Whatever the host, it could infect western gorillas by defecating or leaving saliva on their food, which is mostly fruit. The gorillas could then infect one another, both inside their own social groups and between groups. The virus is spread by bodily fluids, and by touching sick or dead animals. Dr. Walsh said that gorillas commonly ate one another’s dung, which could also transmit the virus. Scientists have debated whether gorillas’ infecting one another or the reservoir host is the main culprit. The new report says the gorillas play an important part: it shows that the spread of the disease and the timing of outbreaks match the pattern that would occur if the animals were infecting one another. If the gorillas are infecting one another, the path of the disease will be fairly predictable, and vaccination may be able to stop it, Dr. Walsh said. (A vaccine would be less likely to succeed if most of the cases were coming from reservoir hosts, because the pattern would be more random and unpredictable.) The Ebola virus alone is not likely to drive gorillas to extinction, Dr. Walsh said. “All the major parks have serious hunting and poaching problems,” he said. “It’s a slippery slope. Ebola is pushing the gorillas onto it, and other factors are pushing them down it.” His goal is to keep the gorilla populations large enough to withstand the other assaults on them, and stopping Ebola would be a step in the right direction, he said. http://www.nytimes.com/2006/12/08/s...93772-bdIo2IabZKgNU3dyTVG4kg&pagewanted=print
