Study of Deer Mice on California’s Channel Islands provides new information on Hantavirus; number of suspected cases of Dengue Fever in Hawaii now approaching 50; and Rabies reports from California, Colorado, and New Hampshire. Canada: A Coyote report from Newfoundland.

Deer mouse. Photo by 6th Happiness. Wikimedia Commons.

 

California 04/19/11 eurekalert.org: by Cheryl Dybas, National Science Foundation – A little information can go a long way when it comes to understanding rodent-borne infectious disease, as shown by a new study led by scientist John Orrock of the University of Wisconsin-Madison and colleagues. The researchers studied wild deer mouse populations on the Channel Islands off the southern coast of California. The mice carry a variant of hantavirus–a disease spread by rodents–called Sin Nombre virus. Results of the study appear in the May issue of the journal American Naturalist. They show that just three ecological factors–rainfall, predator diversity and island size and shape–can account for nearly all the differences in infection rates between the eight islands.

The study also provides some of the first evidence to support a recent hypothesis that predators play an important ecological role in regulating disease–sometimes known as the “predators are good for your health” hypothesis. “These findings support an emerging consensus that ecological factors such as food web structure and species diversity play a key role in determining the prevalence of zoonotic diseases and human health risk,” says Alan Tessier, program director in the National Science Foundation’s (NSF) Division of Environmental Biology, which funded the research.

In humans, Sin Nombre virus causes Hantavirus Pulmonary Syndrome, a virulent and often fatal disease. An outbreak of Sin Nombre virus in 1993 in the Four Corners area of the U.S. Southwest killed several people and brought national attention to the disease. Learning what factors control the prevalence and spread of viruses like Sin Nombre within host populations is crucial for understanding the risks of animal-borne diseases. “The ecological underpinnings of disease prevalence, its dynamics in natural populations and its transmission from animals to humans are important links that are still being deciphered,” says Orrock.

Dr. John Orrock

Mouse populations on the Channel Islands have some of the highest rates of Sin Nombre virus ever measured. That, coupled with the isolation and well-defined food webs of the islands, makes them a good system to study what ecological factors affect the presence of the virus. “The prevalence of disease was found to be a function of ecological variables that humans can measure,” Orrock says. “What this illustrates is that if you know just a few things, you can have a reasonable shot of predicting the disease prevalence.”

Working with Brian Allan from the University of Illinois at Urbana-Champaign and Charles Drost from the U.S. Geological Survey’s Southwest Biological Science Center, Orrock mined an existing dataset. The data were collected on the Channel Islands shortly after the Four Corners outbreak, to look for relationships between biological and physical island characteristics and the prevalence of Sin Nombre on each of the eight islands. The researchers found that 79 percent of the variation in disease prevalence among the islands could be explained by a single factor–average annual precipitation. Adding in the physical characteristics of the islands and the number of predators accounted for a total of 98 percent of the variation. Higher infection rates among Channel Island deer mice were strongly associated with more precipitation, larger island area and fewer predator species. The strong effect of precipitation levels highlights potential links between changing climate regimes and human health.

The results also suggest that more diverse predator populations could help keep animal-borne diseases in check–an important lesson as top predators like wolves and bears increasingly disappear from ecosystems due to habitat loss and conflicts with humans. The authors note that future studies should use experimental methods and examine larger systems to evaluate the generality of the observed patterns. Nonetheless, the strength of the associations they found on the Channel Islands is striking. “What’s shocking about these data is how tight the relationship is,” Orrock says. “Rarely in ecology do you find that one variable will explain 79 percent of the variation in anything. “The fact that precipitation does here, and that adding the effects of predator richness and island characteristics explains nearly all the variation in disease prevalence on these eight islands, suggests that we’re getting to the heart of some basic ecological principles.”

Hawaii 04/18/11 hawaiinewsnow.com: by Minna Sugimoto – Kalihi – There are now nearly 50 suspected Dengue Fever cases in Hawaii awaiting lab confirmation. As the state’s Vector Control Branch continues to struggle with a staffing shortage, the public is being called upon to help. Dengue Fever is spread by mosquitos. In these tight budget times, two Oahu lawmakers are joining forces for an education campaign that, they say, won’t cost a dime, but will do a lot to control Dengue in Hawaii.

The plants are beautiful and so are the pots they’re growing in. But inside each one could be a breeding ground for mosquitos, potential carriers of Dengue Fever. “It’s something that everyone, I think, statewide needs to be very aware of and to be taking preventive measures within their own neighborhoods, within their own homes,” Tulsi Gabbard-Tamayo, Honolulu City Council member, said.

Since March 24th, there have been four confirmed cases of Dengue Fever in Hawaii. Health officials are awaiting lab results for 48 suspected cases. Gabbard-Tamayo and state Rep. John Mizuno hit the streets of Kalihi Valley Sunday to educate their constituents about ways to reduce the spread of the viral illness. “There is a great concern because Department of Health Vector Control is understaffed right now,” Mizuno said. “It’s been decimated with the cuts. We know that but, nevertheless, we have a public safety issue before us.” Therefore, he says residents must do their part by checking for mosquitos, emptying containers of standing water, and spraying suspected breeding areas with dishwashing detergent in water. “That provides a thin film over the surface and it will suffocate your wigglies,” Mizuno said. “They only live for about a week before they’re transformed into mosquito. The mosquito itself will live for about a month.”

The grassroots awareness campaign was supposed to include a former state vector control inspector, who was transferred to another position during a reduction in force two years ago. In the face of a possible Dengue outbreak, Mizuno says that individual is keeping a low-profile as he tries to get his old job back. “He wants to help the public,” Mizuno said. “This is a public safety issue and so he’s willing to take a $700 cut in pay to transfer from another department back to his old position.” Symptoms of Dengue include fever, severe headaches, rash, and eye, joint, and muscle pain. The four confirmed cases in the past month involved residents in Pearl City.

California 04/18/11 dailydemocrat.com: The Yolo County Sheriff’s Department, Animal Services Section is attempting to locate a biting dog in Woodland.  A 58-year-old man was was bitten by a dog which was running in traffic, according to Vicky Fletcher of Animal Control.  The victim tried to assist the dog to get it out of the street when the dog bit him. The event occurred on Thursday about 6:10 p.m. and was reported by the hospital. Animal Services attempted to locate the animal and any witnesses in the area, but was unsuccessful.  The biting dog is described as a brown Chihuahua, of unknown sex. Last seen on Cottonwood Street and Gibson Road.  Information regarding this incident is important for rabies prevention measures. Rabies is a deadly disease, so if the dog is not located soon, the victim may have to undergo rabies treatment. Anyone having any information regarding this incident or knows who owns this animal, should contact Yolo County Sheriff’s Department, Animal Services Section 24 hours a day at 668-5287 or email animal.bite@yolocounty.org.

Colorado 04/18/11 newsfirst5.com: by David Ortiviz – Rabies is on the rise in parts of Colorado and health officials think the worst is yet to come. So far, eight animals have tested positive–mostly skunks–and concern is mounting as they move into residential neighborhoods. In the past six months, seven skunks have tested positive for rabies in Pueblo County numbers like this are unprecedented in the county’s history. “We’re very concerned,” said Carlton. The Pueblo City-County Health Department collects animals suspected of having rabies and sends them to a state lab for testing. In recent months, two rabid skunks were found within city limits. “The big deal is, is that rabies virus is 99.99% fatal. If a person were to contract rabies, more than likely they’re going to die from it,” said Carlton. Experts say people who are bitten by a rabid animal–could survive with immediate treatment. Signs have been posted in Pueblo to warn people the virus is in our community. Experts say be aware of animals with odd behavior: skunks that are docile and friendly or by contrast those that are aggressive and chase after people and pets. “The number one most important thing is to get their pets vaccinated,” said Carlton. Most pet vaccinations can last up to three years. They urge taking precautions now, because the number of positive cases continues to climb. “The expectation right now from everything we’ve seen is that we’ve not hit the peak yet,” said Carlton. In Colorado last year, more than a 136 animals tested positive for rabies. El Paso County had 17 cases and Pueblo County had nine.

New Hampshire 04/19/11 nashuatelegraph.com: by Jake Berry – Excerpts – “A rabid fox tore through a neighborhood and bit at least four people in south Nashua last week before it was killed, according to city health officers. The fox, gray in color, attacked residents Friday afternoon on Browning and Dryden avenues and Lansing Drive, among other areas, before police officer Bob Langis, the department’s animal control officer, shot it. The fox was killed on Peele Drive, near Exit 4 of the F.E. Everett Turnpike. Each of the four victims received rabies shots and other necessary medical treatment, including two children who were playing in the backyard when the fox approached, according to Heidi Peek, manager of the city’s Environmental Health Department.

“The animal is the second from Nashua to test positive in recent weeks – a bat found in an area home was found to have rabies last month. In total, four animals across the state have tested positive this year. There were 17 cases confirmed in 2010, according to Jodie Dionne-Odom, deputy epidemiologist for the state Department of Health and Human Services.” (For complete article go to http://www.nashuatelegraph.com/news/916364-196/rabid-fox-bites-4-in-south-nashua.html )

Canada:

Newfoundland 04/18/11 cbc.ca: Coyote sightings will probably become more common in urban and suburban Newfoundland communities, according to a provincial wildlife official reacting to a report that a coyote was seen in the centre of St. John’s in mid-April. “It’s becoming more, and more common and it probably will get more common as coyote numbers increase,” said Mike McGrath, a senior biologist with the provincial wildlife division. McGrath spoke with CBC News after a man living on Wishingwell Road, in St. John’s, said he saw a coyote near his house over the weekend. “I looked up the road and I saw him on the lawn. I went in my house to get my camera and when I came back out, it was gone,” said Bill Butt. “I knew it was a coyote because I’ve seen them before in British Columbia. It wasn’t a dog.” McGrath has not confirmed that what Butt saw was a coyote, although he said it is possible that it was. “We get the occasional sighting [of coyotes] right throughout the city, including the Goulds, and we had an unconfirmed sighting on Blackmarsh Road the week before last,” he said.

Coyotes came to Newfoundland in 1980s

Coyotes are found throughout North America. They aren’t native to Newfoundland but have been spreading east since they first were sighted on the island in the mid-1980s. The Avalon Peninsula is the last part of the island the animals have reached. McGrath said coyotes feed primarily on snowshoe hares and moose carrion. He believes growth of the province’s coyote population has been fuelled by the island’s growing hare population. “We’re pretty confident that the coyote numbers are responding to that numerically,” he said. “But I think the numbers of coyotes are starting to peak now.” McGrath said coyote numbers in Labrador are low and are not expected to grow because of the presence of wolves there. Last year a woman was killed by coyotes in a national park in Cape Breton, N.S. Nonetheless, McGrath said that although coyotes have been known to kill pets, people in Newfoundland probably aren’t likely to be harmed by them. “The animals [in the Nova Scotia case] were pretty accustomed to people and they were used to getting food from people,” said McGrath. “The animals that lose their fear of people are the animals that we have to be vigilant about. If we keep these animals wild, I don’t think we will ever have problems with coyotes in Newfoundland,” he said.

 
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