Eminent Harvard biologist E.O. Wilson says that fully half of the planet’s higher life forms could be gone within 100 years, joining the dodo bird, sketched here, which has been extinct since the 17th century and whose fate was directly attributable to human activity. Photo: ThinkstockDear EarthTalk: I heard that species of flora and fauna are dying at a growing rate globally. How is this calculated and which types of species are dwindling faster?–– Colin Gooder, Franklin, NCResearchers believe that the rate of species loss currently underway is 100-1,000 times faster than what was normal (the so-called “background rate” of extinction) prior to human overpopulation and its negative environmental effects. But thanks to overhunting, deforestation, pollution, the spread of non-native species and now climate change, we are likely in the midst of the sixth mass extinction in the geologic history of the world. The previous mass extinction, 65 million years ago, wiped out the dinosaurs and other species; the previous one, 250 million years ago, killed off 90 percent of all species on the planet.While the current mass extinction might in reality not be that bad—only time will tell—eminent Harvard biologist E.O. Wilson predicts that the rate of species loss could top 10,000 times the background rate by 2030, and that fully half of the planet’s higher life forms could be gone within 100 years. This jibes with statistics from the non-profit International Union for the Conservation of Nature (IUCN)—keeper of the global “Red List” of endangered species—which currently considers 37.8 percent of the world’s already classified species to be threatened. Of course, this is far from the whole story, as biologists think that we have only classified 10 percent or less of the world’s total number of plant and animal species.Which types of species are being hit hardest? An analysis of IUCN statistics from 2008 found that of the world’s fauna (animals), invertebrates (animals without backbones, such as earthworms, shellfish and insects) were suffering the most, with 40.5 percent of those classified considered threatened. Next hardest hit were fish species, with 36.6 percent threatened, followed by reptiles at 30.5 percent and amphibians at 30.4 percent. Meanwhile, 20.8 percent of mammal species were threatened and 12.2 percent of birds.More shocking was the statistic that some 70.1 percent of plant species are at risk. However, a more recent (2010) study found that only 22 percent of the world’s classified plants are actually facing extinction. This finding has led analysts to question conservationists’ estimates in regard to animal species loss as well.In lieu of any direct way to measure the rate of species loss, conservationists have relied on reversing the so-called “species-area relationship,” whereby scientists tally the number of species in a given area and then estimate how quickly more show up or evolve as viable habitat increases (or decreases in the case of reversing the concept). But lately this method of tracking and predicting species losses has been criticized for generating overestimates. “The overestimates can be very substantial,” argues UCLA evolutionary biologist Stephen Hubbell, “…but we are not saying [extinction] does not exist.”However many species may be dying, it’s clear we are in the midst of another mass extinction, and if you believe 70 percent of biologists, unlike previous mass extinctions humanity is most likely the cause. Conservationists remain optimistic that we can marshal the resources to turn the tide—and we’ll need to if the planet is to remain habitable for our species, given our own dependencies on the world’s biodiversity.CONTACTS: E.O. Wilson Biodiversity Foundation, www.eowilson.org; IUCN, www.iucn.org; “Species-area relationships always overestimate extinction rates from habitat loss,” www.nature.com/nature/journal/v473/n7347/full/nature09985.html.EarthTalk® is written and edited by Roddy Scheer and Doug Moss and is a registered trademark of E – The Environmental Magazine (www.emagazine.com). Send questions to: [email protected] Subscribe: www.emagazine.com/subscribe; Free Trial Issue: www.emagazine.com/trial.
Oct 2, 2006 (CIDRAP News) – Recent tests suggest that an antiviral drug given by intravenous (IV) or intramuscular (IM) injection could eventually serve as another weapon against influenza, according to results presented at a conference last week.In animal studies, peramivir improved survival in mice and ferrets infected with H5N1 avian flu, according to a news release from BioCryst Pharmaceuticals Inc., Birmingham, Ala., which is developing the drug. The results were presented Sep 30 at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco.In addition, in phase 1 clinical studies, IV and IM doses of peramivir produced high blood levels of the drug in human volunteers without causing any adverse events, according to Dr. Charles E. Bugg, PhD, chairman and chief executive of BioCryst.The clinical studies “showed you can achieve high blood levels in humans safely,” Bugg told CIDRAP News in an interview today. The combination of those results with the animal studies is promising, he said.Peramivir is a neuraminidase inhibitor, like the licensed antivirals oseltamivir (Tamiflu), and zanamivir (Relenza). Oseltamivir is an oral drug, while zanamivir is inhaled as a powder. Many countries have stockpiled oseltamivir on the assumption that it will help if the H5N1 virus sparks a pandemic.BioCryst started developing peramivir in 1998 in partnership with Johnson and Johnson, Bugg said. Early studies showed the drug inhibited flu viruses effectively, but when taken orally, its bioavailability was very low, which prompted Johnson and Johnson to pull out of the program.Because injectable peramivir looked promising in animals, the program was resurrected with help from the National Institutes of Health about a year ago, Bugg said. He explained that the company is developing an IV formulation intended for hospital patients and an IM formulation for outpatients.In the animal studies, four groups of mice were infected with an H5N1 virus and then were treated with either a single IM injection of peramvir, five daily IM injections, oral oseltamivir for 5 days, or an IM placebo injection daily for 5 days, according to the news release. The single-injection group had a 70% survival rate and the five-injection group a 80% survival rate, compared with 36% for the placebo group and 70% for the oseltamivir group.In the ferret experiment, one group received a daily IM injection for 5 days, while a second group received an IM placebo daily for 5 days. Eighty-six percent of the treated group survived, versus 43% of the placebo group, according to the news release.Bugg said treatment was started an hour after the animals were infected with the virus. He said additional studies will involve longer time lapses between exposure and the start of treatment.Results of the clinical studies were presented by flu expert Frederick Hayden, MD, of the University of Virginia. Three groups of volunteers received different IV doses of peramivir, and a fourth group received increasing IM doses once a day for 3 days, the company release said. “Preliminary safety results indicate that in the four studies, all doses were well-tolerated with no adverse laboratory events or ECG findings reported,” the statement said.”I think peramivir looks very promising,” said Hayden, as quoted in a Sep 29 Bloomberg News report. “It’s proven to have very good activity in single doses.”In an interview, Hayden told Bloomberg that injecting peramivir into the bloodstream or into muscle can produce blood levels 100 times higher than those seen with oral oseltamivir, now considered the most promising treatment for H5N1 infection.Last January the Food and Drug Administration (FDA) gave injectable peramivir fast-track status for regulatory approval, according to BioCryst. But Bugg said it would take at least several more years to gain FDA approval.”We’ll do a clinical trial this flu season, and then two more next season,” he said. “We’re looking at several more years.” He said the company will be meeting with the FDA soon to review the program and may have a better idea of the timeline after that.Bugg said plans also call for testing the drug in human H5N1 patients at sites in Thailand and Vietnam and also to make it available in Turkey, which had human cases early this year.”We’ll be trying to collect data from H5N1-infected patients in Southeast Asia in collaboration with the World Health Organization,” he said. “We’ll be on the front line to capture H5N1 if it occurs. But realistically we won’t have enough [patients] for a meaningful statistical analysis.”In a Sep 29 Reuters report, Bugg said peramivir is easier to make than Tamiflu. One Swiss manufacturer can make 1 metric ton of the drug in a month, enough to treat an estimated 8 million people, he said.See also:Oct 2 BioCryst release on peramivirhttp://investor.shareholder.com/biocryst/releasedetail.cfm?ReleaseID=213054