动物实验,寄生虫 z-bo 2020-09-01 363

　　A study led by the University of California, Davis and the California Department of Fish and Wildlife said that scientists studying the massive deaths of North American native pigeons have discovered a new pathogen.

　　Three group pigeons inhabiting Santa Barbara County. Researchers from the University of California, Davis and the University of California’s Department of Fish and Wildlife have discovered that trichomoniasis is a key cause of winter death and population decline in this California-native migratory game bird. Image Credit: Courtesy Dianne Ricky

　　Scientists were able to link this new parasite and the ancient parasite Trichomonas gallinae with the recent deaths of thousands of pigeons in the Pacific coast. This type of death has occurred many times in the central coastal areas of California and the Sierra Nevada region. Scientists named this new pathogen Trichomonas stABLeri.

　　Avian Trichomonas is a newly emerging disease with deadly potential. It can cause severe damage that can block the esophagus, and eventually make it impossible for birds to eat, drink, or block the airway, leading to suffocation. The disease may be traced back to when the dinosaurs wandered the earth, because the damage marked trichomoniasis was recently found on the bones of Tyrannosaurus. This disease may also contribute to the decline of passenger pigeons, which became extinct 100 years ago.

　　The epidemic of this disease may cause thousands of poultry to die in a short period of time. An outbreak in the Carmel Valley in 2007 killed an estimated 43,000 birds.

　　"The parasite that killed the band-tailed pigeons in these outbreaks also killed the birds when there were no outbreaks," the first author of the study was at the University of California Davis School of Veterinary Medicine at the time of the study. Yvette Girard, a postdoctoral scholar at the Center for Biological Health, said. "This suggests that this type of death may have other factors at play."

　　"We are now investigating what triggers these deaths, which may be caused by the gathering of infected and susceptible birds under certain environmental conditions, or even by spilling from another species nearby. "Said Christine Johnson, the research team leader and a professor at the Wildlife Health Center at the University of California, Davis.

　　Between the winter of 2011 and the spring of 2012, there were 8 deaths-this is defined as the discovery of more than 5 dead birds in the same geographic area within the same time frame. The study said that 96% of the dead, sick, or dying birds examined in seven of the deaths confirmed trichomoniasis. The disease was also found in the following situations:

　　? 36% of the pigeons in the Wildlife Recovery Center

　　? Pigeons killed by 11% of hunters

　　? 4% of the birds caught and released alive.

　　"What makes this disease even more troublesome for group pigeons is their low reproductive rate-only about one young bird per year-and these events occur in the winter," the study's co-author and the California Department of Fish and Wildlife Environmental scientist Krysta Rogers said. "This means that almost all the birds we lost in these events were adult birds. They were killed before they had the ability to reproduce in winter."

　　There have been reports of marquee deaths in California since at least 1945, but the number has increased in the past 10 years, and outbreaks have been reported in 6 of the past 10 years.

　　"At the time of this research, we expected to find a highly virulent species of Trichomonas in birds sampled during the outbreak," Girard said. "It is surprising that two species killed birds in these mass deaths."

　　The autopsy of these birds was conducted at the California Animal Health and Food Safety Laboratory at the University of California, Davis and the Wildlife Investigation Laboratory at the California Department of Fish and Wildlife.

　　These studies were funded by the California Department of Fish and Wildlife and the US Fish and Wildlife Service.