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5 Oct 05 Bats Passed SARS Virus to Civet Cats - China Expert Channel NewsAsia 1 Oct 05 More research needed on SARS bat link: expert PlanetArk 30 Sep 05 More Evidence Links SARS to Bats Story by Maggie Fox BBC Online, 29 Sep 05 Bats a 'likely source' of Sars By Richard Black Environment Correspondent, BBC News website See also below PlanetArk 12 Sep 05 Bats May Have Been Source of SARS - Study Channel NewsAsia, 11 Sep 05 Bats found to carry SARS-like virus, Hong Kong researchers find AFP HONG KONG : A study in Hong Kong has found that a local bat species carries a virus virtually identical to SARS, the pneumonia-like illness that killed hundreds in a worldwide outbreak, researchers said Sunday. The horseshoe bat, common in Hong Kong's northern rural New Territories, carries a coronavirus that is 90 percent similar to the Severe Acute Respiratory Syndrome virus, which spread through Asia and elsewhere in 2003. "Because of this we think that you should not come into contact with these types of bat," warned Professor Yuen Kwok-yung, microbiologist at the University of Hong Kong, which carried out the study. The year-long probe tested more than 100 animals, including eight species of bat, to help unravel how SARS first emerged. Scientists believe the variant lethal to humans, which killed 800 people in a 2003 global outbreak focused on Hong Kong and China, originated in civet cats, a small racoon-like creature eaten in parts of China. Speaking on local RTHK radio, Yuen said he believed the type of coronavirus found in the bat was unlikely to be as dangerous as that found in civet cats. "I think the risk of the bat coronavirus going to humans is low ... because the (civet cat) variant is more able to adapt," he said. - AFP /ct PlanetArk 12 Sep 05 Bats May Have Been Source of SARS - Study WASHINGTON - Bats found in Hong Kong carry a virus very similar to the severe acute respiratory syndrome or SARS virus and might be able to spread it, Chinese researchers reported on Friday. They said the horseshoe bats, valued both as food and for their use in Chinese medicine, should be handled with great care. They may have helped spread the virus among different species of animals, the researchers said. SARS first emerged in China in 2002 and in 2003 spread around the world via jet, killing more than 700 people and infecting around 8,000. It is caused by a new virus called SARS coronavirus. Coronaviruses are common in people and animals and usually cause nothing more serious than a cold. But SARS was different. "The isolation of SARS-coronavirus from caged animals, including Himalayan palm civets and a raccoon dog, from wild live markets in mainland China suggested that these animals are the reservoir for the origin of the SARS epidemic," Kwok-yung Yuen of the University of Hong Kong and colleagues wrote in their report, published in the Proceedings of the national Academy of Sciences. "However, several lines of evidence suggested that the civet may have served only as an amplification host for SARS virus and provided the environment for major genetic variations permitting efficient animal-to human and human-to-human transmissions," they added. So they studied wild animals in the Hong Kong countryside that may have come into contact with civets. They found a coronavirus similar to SARS in nearly 40 percent of wild Chinese horseshoe bats they examined. Genetic analysis of the bat SARS virus showed it was closely related to the human SARS coronavirus. The researchers could not determine how the bats were originally infected or whether bats were responsible for transmitting the SARS coronavirus to other mammals including the civets. But because bat feces are used in Chinese traditional medicine, and bat meat is considered a delicacy in parts of Asia, the researchers suggest caution in handling them "Interestingly, the nearest wildlife market previously found to have animals with SARS in Shenzhen is only 10 miles (17 km) away from the locations with bats harboring bat-SARS in (Hong Kong)," the researchers wrote. PlanetArk 30 Sep 05 More Evidence Links SARS to Bats Story by Maggie Fox WASHINGTON - Many species of bats found across China are infected with viruses similar to the SARS virus, an international team of researchers reported on Thursday. Zhengli Shi of the Chinese Academy of Sciences in Beijing and colleagues sampled more than 400 bats of various species across China and found up to 70 percent of some species showed evidence of infection with SARS-like viruses. This would support the idea that bats are the reservoir -- the natural host -- of the virus. Animals that act as reservoirs carry and spread a virus without themselves becoming ill. Severe acute respiratory syndrome or SARS first emerged in China in 2002 and in 2003 spread around the world via jet, killing more than 700 people and infecting about 8,000. Strict quarantines and other measures stopped its spread. It is caused by a new virus called SARS coronavirus. Coronaviruses are common in people and animals and usually cause nothing more serious than a cold. Animals such as palm civets were found to be infected but study showed they were not the true reservoir of the SARS virus. Earlier this month a team of Hong Kong researchers reported that bats found in Hong Kong carried a virus very similar to the SARS virus. They said the horseshoe bats, used both as food and in Chinese medicine, should be handled with great care. Shi, Wendong Li and colleagues studied other bats found in four different parts of China. They found that anywhere between 28 percent and 71 percent of the bats, depending on the species and location, had evidence of infection with a SARS-like coronavirus. Theirs was different from the virus found by the Hong Kong researchers, they said. "A plausible mechanism for emergence from a natural bat reservoir can be readily envisaged," they wrote in their report, published in the journal Science. They said an infected bat could have been kept in a cage next to a civet in a market with the civet becoming infected and passing the virus to humans. Bats are hosts of several other new viruses, including Hendra and Nipah viruses, and rarely become ill. Channel NewsAsia 1 Oct 05 More research needed on SARS bat link: expert BEIJING : A Chinese expert has urged more research to test the hypothesis that wild bats are the source of the SARS virus that killed about 800 people worldwide nearly three years ago, state media said on Saturday. Research published this week showed a 92 percent match between a bat virus strain and the coronavirus for Severe Acute Respiratory Syndrome, according to the China Daily. That would seem to make bats a much likelier culprit than other animals previously seen to be suspects, such as civet cats, but Chinese experts are not convinced, according to the paper. "The current report only raises a hypothesis that the bats might be the source of the virus," said Liu Qiyong, an expert in diseases from the Chinese Centre for Disease Control and Prevention. "The 92 percent similarity may mean nothing and does not prove the bat was the original host. Even if two viruses are more than 99 percent similar to each other, we still cannot say that they have a host relationship," Liu said. Further research must show that the virus carried by bats developed into the SARS virus and track its path via civet cats to humans, according to Liu. - AFP/de BBC Online, 29 Sep 05 Bats a 'likely source' of Sars By Richard Black Environment Correspondent, BBC News website The likely source of the respiratory disease Sars is the horseshoe bat, a new study suggests. Researchers found a virus closely related to the Sars coronavirus in bats from three regions of China. Writing in the journal Science, they say the virus may have needed to infect another animal such as the civet before it could transmit to humans. They suggest that live horseshoe bats are kept out of markets until the transmission path is fully understood. The Sars (Severe Acute Respiratory Syndrome) outbreak in 2002/3 caused about 770 deaths, and economic damage estimated in billions of dollars. Centred on east Asia with origins in southern China, fatalities occurred as far afield as Canada. Schools and businesses closed, international trade and travel were restricted; and for a time, until basic public health measures curtailed the outbreak, it seemed as though the next major global disease of humanity had emerged. But emerged from where? In May 2003, the suggestion was that the virus responsible had entered the human population from civets, animals eaten in wildlife restaurants and butchered in live animal markets in southern China. The World Health Organization (WHO) endorsed this link early in 2004, an announcement which led authorities in China to embark on a culling programme which saw an estimated 10,000 civets killed, as well as other animals suspected of harbouring Sars, such as badgers and raccoons. Immunity clue But for some time, the prevailing theory among scientists has been that civets were not the original source, or reservoir, of infection. One clue is that they appear to have little immunity, and become seriously ill; whereas species which harbour pathogens for a long period of history usually adapt to them. So where did the Sars virus, labelled Sars-CoV, come from? One theory named birds; but earlier this month, researchers at Hong Kong University found cause to suspect bats. In a Hong Kong bat species they found a virus closely related to that found in Sars patients. Now an international collaboration between scientists in China, Australia and the US has gone further, and identified a Sars-like virus in three species of bats from mainland China. "The virus we found is 92% similar to the human Sars virus," said Zhengli Shi, from the Institute of Zoology at the Chinese Academy of Sciences, Beijing. "Why it is there in these bats, why it can infect just these species, we are not sure - it is a story we want to discuss," she told the BBC News website. All three species of bat in which Dr Shi's group found the Sars-like coronavirus, dubbed SL-CoV, are horseshoe bats of the genus Rhinolophus, as is the species identified in the Hong Kong study. Civets still implicated? Genomic analysis suggests that the bat coronaviruses found by this group and by the Hong Kong team are very alike, and that both are closely related to the human and civet forms. The major differences lie in genes which relate to the binding of virus particle and host cell. "This virus, we are sure, cannot infect humans," said Zhengli Shi. One of the big questions is, then, how the virus jumped from bats to humans - and whether in the body of an intermediary, such as the civet, it can adapt in such a way that it can then infect a human. "At the moment we don't know," said Peter Daszak, director of the Consortium for Conservation Medicine in New York, US, who was also involved in the study. "But we can make a comparison with other viruses - for example, we don't know what the original host is for Ebola, but it appears to get into chimpanzees first, and then into humans. "Nipah virus, which emerged in Malaysia in 1998 and 99, we believe has fruit bats as the reservoir, but it had to go into pigs before it could infect humans." So civets could be an "amplifier host" for Sars. If they are, one suggestion, according to Peter Daszak, is to keep them away from horseshoe bats. "In the east Asian region, we need to face up to high-risk behaviours," he said, "and in this situation, bringing these species into live markets, butchering and eating them and using them in medicines, is a high-risk behaviour." Solving the jigsaw WHO spokesperson Dick Thompson told the BBC News website: "We see this as another piece of the Sars jigsaw. "There's an unfinished agenda for Sars, and clearly we need to understand the disease ecology better." The Chinese team plans to examine the possible transmission path of the virus more closely. "We will change some amino-acid sequences in the virus we have identified," said Zhengli Shi, "and see if can infect humans." Confirming horseshoe bats as the source of Sars would carry implications for future public health research and policy. "These bats have a wide distribution in Europe and Asia," said Peter Daszak, "and what we don't know, and need to know urgently, is the distribution of the Sars-like virus in these bats. "On a wider scale, we need surveillance of wildlife to look for possible new diseases, and to identify changes in the environment, human behaviour and demography which drive the emergence of these diseases; because almost every new disease which has emerged recently has been driven by changes in land use. "The last thing we should do is to take it out on the bats, because the evidence suggests that they have carried this coronavirus for thousands, perhaps millions, of years; only recently has it emerged in a big way, and it was human behaviours that made the difference." PlanetArk 5 Oct 05 Bats Passed SARS Virus to Civet Cats - China Expert HONG KONG - A species of bats in China might have been the source of the SARS epidemic in 2003, a Chinese health expert said on Tuesday, adding that the creatures probably passed it to civet cats, which then passed it to humans. Researchers in Hong Kong and China said last month that the horseshoe bat - a delicacy in southern Chinese cuisine and whose faeces are used in traditional Chinese medicine - was a natural host of SARS-like viruses, meaning it could carry the bugs but not fall ill. Zhong Nanshan, China's leading SARS expert, said these bats were stored in cages while waiting for buyers in wholesale markets in southern Guangdong province and may have easily passed on viruses to other species. SARS, or Severe Acute Respiratory Syndrome, began spreading in Guangdong in late 2002 and among its earliest victims was a chef who handled civet cats. There has however been no documented case of humans contracting SARS directly from horseshoe bats. Hong Kong scientists have said the SARS virus jumped from civet cat to humans and quickly developed the ability to pass from person to person. The disease spread to about 30 countries in 2003 via air travel, killing some 800 people in all. Zhong said civet cats farmed in other Chinese provinces such as central Hubei and Hunan and southern Guangxi were not found to carry the virus. But once they got to markets in Guangdong, up to 78 percent of them were found to be hosting the virus. "So how did the civet cats get SARS? The view is horseshoe bats are a very important reservoir for SARS," Zhong said. "Could it be that in the wild animal markets they were kept close to civet cats and then passed the virus to them? "Guangdong's wild animal markets are a very important transmission ground for SARS," Zhong said. He also described civets as playing the role of an "amplification tool" in the SARS epidemic. Once they contracted it, they spread it among themselves like wildfire. Researchers have however not been able to determine how the bats were originally infected. SARS is caused by a virus which belongs to the family of coronaviruses. Coronaviruses are common in people and animals and usually cause nothing more serious than a simple cold. But the SARS virus proved to be very deadly, and had a mortality rate of 10 percent in 2003. links Related articles on Global issues: biodiversity biodiversity loss, extinction threats, commercial applications of biodiversity |
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