More than half of infectious diseases, including SARS and emerging-human Ebola come from animals
more than half of the new infectious diseases that afflict humanity, including avian influenza, West Nile virus, SARS and even Ebola derived from animals. Now, new findings suggest that many of these outbreaks could have been detected earlier, and potentially prevented, had a wildlife monitoring program was in place.
-zoonotic diseases that jump from animals to humans have become more common in the last 60 years. Biologists blame people, who have increasingly encroached on wildlife habitats. It is expected more opportunities for diseases to jump from animals to humans. wildlife monitoring could signal in advance emerging diseases and give health authorities a chance to minimize the spread of an epidemic or better prepared when a human outbreak occurs. Yet little or no public health programs include wildlife monitoring.
In the new study, a team led by Isabelle-Anne Bisson, a conservation biologist with the Biology Smithsonian Conservation Institute in Washington DC, has undertaken to determine whether information on the health of wildlife could be used to predict the onset of disease in humans. The team examined historical records of nearly 150 pathogens known to jump from wildlife to humans. They searched through 60 years of scientific reports and logs to determine two things :. First, if the pathogens causing symptoms of visible disease or death in wild animals, and secondly, if human outbreaks were preceded or accompanied by evidence of the disease in animals
"These pathogens are invisible to the human eye, "said Bisson. "You can not see them moving through a landscape, but you can certainly identify with the sick and dead animals."
The team found that, of the nearly 150 studied pathogens, 75 caused visible symptoms in animals, such as seizures, lethargy, unprovoked aggression, or death, meaning signs of the disease could be easily detected. In reality, however, only 13 outbreaks of disease in humans have been preceded by reports of wildlife. This suggests that the early warning signs for 64 pathogenic agents-zoonotic 45% of the total-could have been missed, reports the online team this month Ecohealth .
"This study shows above the disconnect between monitoring of diseases in animals and in people," writes Craig Stephen, a veterinary epidemiologist at the Canadian Wildlife Health Cooperative in Saskatoon, which does has not been involved in the work, in an email. "He [demonstrates] the need to respond to the signals in nature and animal health."
"health of wildlife is an important signal of environmental change, not only infectious disease, and is a very useful tool to predict threats to human health," says Kathleen Alexander, an environmental disease and wildlife veterinarian at the Virginia Polytechnic Institute and State University in Blacksburg, who was not involved in the study.
Ebola is an example. After previous outbreaks of the virus in northeast Gabon and the northwest of the Republic of Congo in 01, Gabon and the Congolese Ministries of Forestry and Environment, and several organizations of wildlife set up a temporary network monitoring animal mortality. Its purpose was to gather information from local hunters on their observations of dead primates and other mammals. Carcasses were then tested for the presence of virus. wild animal epidemics occurred before each of the five human outbreaks between 01 and 03, and twice the tracking information was used to alert health authorities of an imminent risk of weeks of exposure before a human epidemic occurred . a rapid response system had been in place, experts say, warning of the advance could be used to implement actions to prevent the spread of the disease. (Whether a wildlife monitoring program could have minimized the extent of the current outbreak of Ebola in West Africa is unknown.)
Although an ideal surveillance program include sampling of both wildlife healthy and sick by trained professionals, the researchers propose that cheaper alternatives could be used to efficiently collect information. The widespread use of mobile technologies like cell phones could enable the public to participate in the declaration of death of the suspect animals.
Since the team finished their analysis, at least two new zoonotic diseases have emerged-the strain of avian influenza H7N9 and Middle East respiratory syndrome. "We really need to have in place surveillance systems," said Bisson. "It is a problem that will become more and more."
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