The findings, published today (Wednesday, Feb. 25) in the journal PLOS ONE, shine a light on an important new reservoir in the western United States for the corkscrew-shaped bacterium, Borrelia burgdorferi, responsible for Lyme disease. Wood rats, western gray squirrels and other small mammals have been identified in previous studies as wildlife hosts of the Lyme disease spirochete bacterium in California, but fewer studies have looked at the role of birds as reservoirs.
“The role of birds in the maintenance of Lyme disease bacteria in California is poorly understood,” said study lead author Erica Newman, a UC Berkeley Ph.D. student in the Energy and Resources Group and the Department of Environmental Science, Policy and Management. “This is the most extensive study of the role of birds in Lyme disease ecology in the western United States, and the first to consider the diversity of bird species, their behaviors and their habitats in identifying which birds are truly the most important as carriers.”
Moreover, the birds in the study that were found to be important hosts of Lyme disease bacteria, such as American robins, dark-eyed juncos and golden-crowned sparrows, are coincidentally ones that are commonly found in suburban environments.
According to the Centers for Disease Control and Prevention, Lyme disease is the most commonly reported tick-borne illness in the United States. There are approximately 30,000 cases reported each year, with the large majority occurring in the eastern United States. However, because actual cases are often underreported to the CDC, the agency notes that the number of people in this country diagnosed with the disease every year may be 10 times higher.
Mobile birds could spread disease
Morgan Tingley, an ornithologist who was not part of this UC Berkeley-led study, underscored the significance of discovering which birds are carriers of Lyme disease bacteria. Tingley, now an assistant professor of ecology and evolutionary biology at the University of Connecticut, conducted studies on range shifts in birds in response to climate change while he was a graduate student at UC Berkeley.
“Birds are much more capable of carrying diseases long distances than the small-mammal hosts typical of Lyme disease, and so may constitute an underappreciated component of Lyme disease ecology,” said Tingley. “Particularly as we look to the future, birds may end up playing a larger role in disease ecology than other animals because of their ability to quickly and easily move long distances and to new habitats. In the same way that airplanes can help spread disease across nations, birds do the same thing for our ecosystems.”
Lyme disease is spread to humans through the bite of infected ticks. The black-legged deer tick (Ixodes scapularis) transmits B. burgdorferi in the eastern and north-central regions of the United States, while the western black-legged tick (Ixodes pacificus) spreads the bacteria in the West.
The bird and tick samples in this new study came from 14 sites within the UC Hopland Research and Extension Center in northwestern California. The study included multiple natural habitats, ranging from savannas and grasslands to chaparral and dense woodlands.
Co-authors Lars Eisen and Rebecca Eisen, both UC Berkeley postdoctoral researchers at the time, took blood samples from 623 birds representing 53 species. The Eisens, both now at CDC’s Division of Vector-Borne Diseases in Fort Collins, Colorado, also carefully removed and identified any ticks they found on the birds. They collected a total of 284 juvenile ticks – more than 99 percent were western black-legged ticks – consisting of 192 larvae and 92 nymphs.
Birds as Lyme disease reservoirs
Lyme disease spirochetes were detected in 57 of the 100 birds that carried ticks. Among the ticks themselves, 13 percent of the larvae and nearly 25 percent of the nymphs were infected with B. burgdorferi or related spirochetes.
Among the 23 species of birds that were infected, the study authors highlighted the lesser goldfinch, oak titmouse and dark-eyed junco as birds that harbored more subtypes of Lyme disease bacteria than others. In addition, the golden-crowned sparrow was infected more frequently than other species.
Previous studies that tested birds have identified the dark-eyed junco as a likely source of Lyme disease bacteria for ticks that feed on them.
Perhaps one of the most surprising results of this study is that “another species of Lyme disease spirochete closely related to, but distinct from, Borrelia burgdorferi was detected in birds for the first time anywhere in the world,” said study co-author Robert Lane, a medical entomologist and UC Berkeley Professor of the Graduate School, and a leading expert on ticks and Lyme disease.
That spirochete, named Borrelia bissettii, has been known to cause a Lyme disease-like illness in people in central and southern Europe. Furthermore, this bacterium was the most common of the Borrelia species found in birds.
“The fact that we found this particular bacterium for the first time in birds in California is notable because of the ease with which birds can distribute spirochetes to different regions,” said Lane. “It is worth watching to see if this spirochete expands in this state.”
Tick-infested birds were found in all types of habitat studied, but the researchers unexpectedly found that chaparral correlated with the lowest counts of larvae and nymphs on birds among the ecosystems studies.
“Other studies have shown that there are plenty of ticks in chaparral, but that was not translating to transmission of Lyme disease bacteria in birds,” said Newman. “This is important because part of the fire management strategy in this state is to remove fire-prone chaparral. What this means for birds is that many species that only live in chaparral are then replaced by species from other habitats, some of which we also now know are more important carriers of Lyme disease bacteria. Our study suggests that by removing chaparral, we may be increasing the spread of Lyme disease in California.”
-------------------- KarlaL Posts: 694 | From New Lebanon, NY | Registered: Dec 2010
| IP: Logged |
quote: That spirochete, named Borrelia bissettii, has been known to cause a Lyme disease-like illness in people in central and southern Europe. Furthermore, this bacterium was the most common of the Borrelia species found in birds.
"The fact that we found this particular bacterium for the first time in birds in California is notable because of the ease with which birds can distribute spirochetes to different regions," said Lane. "It is worth watching to see if this spirochete expands in this state."
Considering what we already know about the distribution of borrelia spp., if this is "the most common of the Borrelia species found in birds" it can surely already be found in a much wider area than California.
Posts: 474 | From US | Registered: May 2014
| IP: Logged |
lpkayak
Honored Contributor (10K+ posts)
Member # 5230
posted
Omg...does anyone remember my post last year. I was sitting at my desk looking out window at a robin on the patio. It had so many ticks it was hard to see the feathers. It totally grossed me out.
My neighbors have a bird feeder that upsets me cuz they keep it up 24/7 and we are told to take them down in spring when bears come out of hiberntion
There is also a flock of doves that eat there and roost on roofs and they creep me out cuz i got very sick from school building where attic was infested with birds and bats and over a foot of poo had piled up in attic
And....that yard is also full of grey squirrels so it makes sense the animals are reinfecting each other and the ticks are infesting yards and probab k y our chipmunks and mice too
Yuk. I am in nh....about as far away as you can get from ca...it must be happening everywhere
-------------------- Lyme? Its complicated. Educate yourself. Posts: 13712 | From new england | Registered: Feb 2004
| IP: Logged |
posted
We have the oak titmice out here. I see them a lot in the trees and shrubs.
I stopped feeding the birds last year. I used to love seeing the differnt kinds at the birdfeeder, but cannot take the chance of spreading more disease. I will probably never again put up my feeder.
There are many chipmunks, too. Not to mention the absolute explosion of deer "herds" in this area.
Posts: 35 | From Eastern U.S.A. | Registered: Feb 2015
| IP: Logged |
posted
Called nature...and it's always there. Honestly, the super LLMD I saw, told me I should not have a birdfeeder, should move out of my home and the only shot I had to survive was to move into a highrise in center city that didn't allow pets.
Also told me to get rid of my dog and 2 cats.
I love animals and THAT LIFE? wouldn't be a life at all.......I made the choice to tell her I couldn't nor wouldn't want to live that way.
It's all choice and I think we all know that ANY animals/birds/wildlife is prey to lyme+...as are we.
I worked in the city years ago and a resident came into work and found a tick on her head in a meeting. I helped her remove it. She wondered how did she get it, then realized she parked her car under a tree downtown.
Kind of made me realize, we cannot run from it and the only way to overcome it is a true vaccine or cure......avoiding really isn't possible.
Just my own take and trying to avoid all of nature or animal habitat just isn't realistic.
Had a friend who lived solely in the city and swore she picked one up at the airport (a tick) in baggage pickup and asked what could she do to avoid it? I had no answer........except to say, expect it's a possibility anywhere, anytime and check yourself every day.
What else could I say?
Posts: 867 | From PA | Registered: Jan 2006
| IP: Logged |
posted
Very interesting report. We are having the biannual LDAC meeting Thursday March 12 here in CA, in Sacramento, starting 9:30am our time, going until at least noon.
The LDAC committee - Lyme Disease Advisory Committee - has 10 people on it who advise the state about Lyme disease management. Entomologist Bob Lane is on the committee!
We listen to them and then public comment happens at the end, for 3 minutes each. Anyone can listen in. I can post the call-in number and passcode when we see it posted.
I think the chaparral removal issue is an interesting one, given the drought here, and I wonder whether it will get discussed, or any of us could ask about it further during public comment.
Posts: 13171 | From San Francisco | Registered: May 2006
| IP: Logged |
posted
Healthywealthy - there are ways to practice some avoidance, like keeping a pet indoors if it's a cat, having really good tick repellent on the animals and on our clothing, gear and skin - just as much as we can do.
Posts: 13171 | From San Francisco | Registered: May 2006
| IP: Logged |
posted
I compromise by just keeping my bird feeder up in the winter when the ticks are not active.
I also love animals and won't give up my dogs. Now that they are older they can't get on the furniture by themselves and we are safer as a result.
I still take walks in nature but only with tick-protection on cleared trails.
We have not left our house in the woods, but I have stopped gardening or working on our yard. I miss this and our yard is a mess. I really need a professionally treated head to toe tick-repellent outfit for this, and I haven't gotten one yet.
-------------------- KarlaL Posts: 694 | From New Lebanon, NY | Registered: Dec 2010
| IP: Logged |
lpkayak
Honored Contributor (10K+ posts)
Member # 5230
posted
It sounds like you dont know that permethrin is the only spray that kills ticks immediatly. The other stuff might slow them down but they still have time to attach and make you sick
-------------------- Lyme? Its complicated. Educate yourself. Posts: 13712 | From new england | Registered: Feb 2004
| IP: Logged |
Tincup
Honored Contributor (10K+ posts)
Member # 5829
posted
May I suggest? Cause I am a big bird fan...
If you put out a bird feeder the birds become dependent on the seed and don't always learn to forage for their own food in the winter as they are suppose to do.
If you remove the feeder BEFORE seeds on plants/trees, etc have developed, that would provide food for the birds, they can starve to death.
If you keep the feeder up until late spring the birds will start leaving on their own as seeds in the wild become available.
If you leave it up longer than that it will feed rodents and other undesirables.
So you can have the best of both worlds and still help the birds through feeders.
Tincup
Honored Contributor (10K+ posts)
Member # 5829
posted
Talk about bears! Oh my! New study... look at all the diseases they harbor!
Demographic Characteristics and Infectious Diseases of a Population of American Black Bears in Humboldt County, California
Vector-Borne and Zoonotic Diseases Volume: 15 Issue 2: February 20, 2015
ABSTRACT American black bears (Ursus americanus) are common, widely distributed, and broad-ranging omnivorous mammals in northern California forests. Bears may be susceptible to pathogens infecting both domestic animals and humans.
Monitoring bear populations, particularly in changing ecosystems, is important to understanding ecological features that could affect bear population health and influence the likelihood that bears may cause adverse impacts on humans.
In all, 321 bears were captured between May, 2001, and October, 2003, and blood samples were collected and tested for multiple zoonotic and vector-borne diseases.
We found a PCR prevalence of 10% for Anaplasma phagocytophilum, and a seroprevalence of 28% for Toxoplasma gondii, 26% for Borrelia burgdorferi, 26% for A. phagocytophilum, 8% for Trichinella spiralis, 8% for Francisella tularensis and 1% for Yersinia pestis.
In addition, we tested bears for pathogens of domestic dogs and found a seroprevalence of 15% for canine distemper virus and 0.6% for canine parvovirus.
Our findings show that black bears can become infected with pathogens that are an important public health concern, as well as pathogens that can affect both domestic animals and other wildlife species.
The Lyme Disease Network is a non-profit organization funded by individual donations. If you would like to support the Network and the LymeNet system of Web services, please send your donations to:
The
Lyme Disease Network of New Jersey 907 Pebble Creek Court,
Pennington,
NJ08534USA http://www.lymenet.org/
UBBFriend: Email this page to someone!
Printer-friendly view of this topic