Stress bites! Researchers study mosquito/bird interactions

Research shows stressed-out birds more attractive to mosquitoes, raising fears birds exposed to stressors such as road noise, pesticides and light pollution, will be bitten more often and spread more West Nile virus

Date: August 10, 2016

Source: University of South Florida (USF Innovation)

When researchers from the University of South Florida (USF) and colleagues investigated how the stress hormone, corticosterone, affects how birds cope with West Nile virus, they found that birds with higher levels of stress hormone were twice as likely to be bitten by mosquitoes that transmit the virus. Their studies have implications for the transmission of other viruses such as Eastern Equine Encephalitis, and perhaps even Zika, both known to be carried by the kind of mosquitoes used in this study.

A paper describing their research was published in the Proceedings of the Royal Society B.

"Few studies have considered how stress hormone effects on individuals might influence population dynamics," said study lead author Dr. Stephanie Gervasi, who conducted the studies while carrying out her postdoctoral work at USF and is now at the Monell Chemical Senses Center in Philadelphia. "For vector-borne diseases such as West Nile virus, the presence of corticosterone could influence pathogen spread through effects on contact rates with the mosquitoes that transmit it. In addition, stress hormones have negative effects on animals including immunosuppression and increased susceptibility to infections, which is why we are now also studying how corticosterone affects the birds' immune response to the virus."

According to the researchers, mosquitoes use a variety of cues to locate a target, including carbon dioxide output, body size and temperature. They hypothesized that these signals coming from a bird could convey information about stress hormones making the birds more appealing targets for the insects.

Continued  

West Nile virus killing millions more birds than previously thought

Date:  November 2, 2015

Source:  Washington University in St. Louis

Many people remember the arrival of West Nile in North America in 1999, if only because the initial outbreak killed not just wild crows but also exotic birds in the Bronx Zoo.

In the following years, a trail of dead crows marked the spread of the virus from the East through the Midwest on to the West Coast. It took only four years for the introduced virus to span the continent.

But what happened to bird populations in the wake of the virus's advance? Were some species decimated and others left untouched? After the initial die-off were the remaining birds immune, or mown down by successive waves of the disease? Nobody really knew.

Now, a study published in the Nov. 2 issue of Proceedings of the National Academy of Sciences provides some answers. The study, a collaboration among scientists at Colorado State University, the University of California at Los Angeles, Washington University in St. Louis and the Institute for Bird Populations (IBP), is the first to fully document the demographic impacts of West Nile virus on North American bird populations.

The scientists analyzed 16 years of mark-recapture data collected at more than 500 bird-banding stations operated using the Monitoring Avian Productivity and Survival protocol developed by IBP, a California-based nonprofit that studies declines in bird populations.

Read more …

Birds roosting in large groups less likely to contract West Nile virus

Date:

October 23, 2014

Source:

University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)

Summary:

Although it would seem logical that large numbers of roosting birds would attract more mosquitoes that carry West Nile virus and contract the disease when bitten, recent research has found the opposite to be true. That is, when large groups of birds roost together the chances that an individual bird will get bitten by mosquitoes carrying West Nile virus and subsequently contract the disease actually go down.

Continued ...

DHEC wants SC residents to collect dead birds

BY NATHANIEL CARY

The Greenville NewsApril 16, 2014 

Birds that could be infected with West Nile virus

SC-DHEC

GREENVILLE, SC — If you see a dead bird, South Carolina’s health department wants you to pick it up, with gloves on of course.

The state wants citizens to collect birds that recently died to help the Department of Health and Environmental Control monitor the spread of West Nile virus in South Carolina this year.

The virus begins to show up in mid-March and normally lasts through November, DHEC says.

If you spot a dead blue jay, crow, house sparrow or house finch, you should put on gloves or use double layers of plastic bags to pick it up and take it to local collection stations, said Chris Evans, an entomologist with DHEC’s Bureau of Laboratories.

West Nile is carried through the bird population, but mosquitoes that feast on birds can spread the virus to humans, Evans said.

Continued

Read more here: http://www.thestate.com/2014/04/16/3389960/dhec-wants-sc-residents-to-collect.html?sp=/99/205/&ihp=1#storylink=cpy

27 eagle deaths in Utah caused by West Nile Virus

The mystery illness that has killed 27 bald eagles in Utah this month appears to be West Nile Virus, state officials said Tuesday.

The Utah Division of Wildlife Resources said in a statement that laboratory tests done on some of the first birds found indicate they died from West Nile Virus.

Since Dec. 1, officials have found the birds in northern and central Utah. All were either dead or were ill and later died during treatment.

The eagles displayed similar symptoms, including head tremors, signs of seizures, weakness in legs and feet and a paralysis of the bird's wings.

continued

Did wild birds cause the 2010 deadly West Nile virus outbreak in Greece?

In 2010, 35 people in Greece died from a West Nile virus (WNV) outbreak, with a further 262 laboratory-confirmed human cases. A new article published in BioMedCentral's open access journal Virology Journal examines whether wild or migratory birds could have been responsible for importing and amplifying the deadly virus.

WNV is a flavivirus of major public health concern, spread through the bite of infected mosquitoes. Discovered in Uganda in 1937, it was only sporadically reported up until the 1990s, after which disease outbreaks were reported world-over, leading to WNV being given epidemic status. Studies have shown that humans infected with WNV do not have viremia levels high enough to infect new mosquitoes and hence pass on the virus. Birds, however, do develop viremia levels sufficient to infect mosquitoes, hence serving as amplifying hosts for WNV.

In order to investigate whether wild birds were exposed to WNV prior to the 2010 outbreak in Greece, Charalambos Billinis and his co-authors tested serum and tissue samples from 295 resident and migratory wild birds harvested by hunters prior to and during the outbreak. These samples were collected for the purposes of the authors' participation in an FP7 EU wildlife diseases research project ("WildTech"). All sampling sites were in flying distance for avian species. Using immunofluorescence assays and virus neutralization tests to analyze samples for the presence of WNV-specific antibodies, the authors found 53 avian samples with WNV neutralizing antibodies. Importantly, 14 positive serum samples were obtained from birds up to 8 months prior to the human outbreak, and genetic determinants of increased virulence were present in these samples.

Source: BioMed Central

Continued:  http://www.sciencecodex.com/did_wild_birds_cause_the_2010_deadly_west_nile_virus_outbreak_in_greece-101827

Bird Infected with West Nile Virus Found in San Rafael

West Nile Virus activity wanes as temperatures drop, but the Marin/Sonoma Mosquito and Vector Control District announced this week that five more infected birds—one in San Rafael—tested positive.

That brings a total of five WNV-positive birds in Marin County this year - in San Rafael, Novato, Ross, Corte Madera and Greenbrae - but the number isn’t expected to rise by much this year.

“During the summer is when WNV transmission is most likely to occur due to the abundance of vector mosquitoes as well as the warmer weather,” said Nizza Sequeira, the district’s public relations director. “We actually do have mosquitoes year round in both Marin and Sonoma counties but they are most abundant during the spring and summer months and begin to taper off into fall.”

That’s not to say all mosquito activity comes to a halt.

“As we enter the cooler months mosquitoes are not as active but will continue to reproduce,” said Sequeira. “For example, we will see more of what we call the cool-weather mosquito (Culiseta incidens) and the large winter mosquito (Culiseta inornata).”

Read on:  http://millvalley.patch.com/articles/wnv-infected-bird-found-in-san-rafael

Summit Outside: West Nile and birds

West Nile virus is closely linked to birds. When it first appeared in 1999 some rare species of birds died suddenly in a New York zoo. At the same time, several people came down with encephalitis (a disease which affects the brain). It was later found to be West Nile virus, a virus never before seen in the United States. It is called “West Nile” because it was first identified in the West Nile sub-region in the East African nation of Uganda in 1937. Over the next five years, the virus spread across the continental U.S., north into Canada, and southward into the Caribbean Islands and Latin America. WNV is now in Africa, Asia, Australia, the Middle East, Europe and in the U.S.

Currently in the U.S., we are experiencing one of the worst epidemics. The disease has been reported in people, birds or mosquitoes in 48 U.S. states.


Continued: http://www.summitdaily.com/article/20120923/NEWS/120929925/1078&ParentProfile=1055

Another Dead Bird in Culver City Tests Positive for West Nile Virus

Another dead bird testing positive for West Nile Virus has been discovered in Culver City.

The Los Angeles County West Vector & Vector-Borne Disease Control District based in Culver City announced the discovery on Sept. 18. It is the eighth bird that has now tested positive for the virus in Culver City (see attached PDF to the right of this article with a breakdown of neighborhoods and zip codes).

Culver City residents who discover a dead bird should call 1-877-WNV BIRD (1-877-968-2473). Dead birds must be less than 24 hours old to be able to test them for West Nile virus. If the bird is rigid or decomposed, it cannot be used for testing.

According to the Disease Control District, birds that are not in a condition to be tested can be disposed of in your normal weekly trash by taking the following steps:

• Take plastic garbage bag and insert your hand in the open end.
• Grab the dead bird and pull it into the garbage bag using an “outside-to-inside” pulling motion.
• Tie off the bag with the bird inside and place it in your regular trash for disposal.

The District does not pick up and disposed of dead birds that are not in a condition to be tested. Animal Control should be called for disposal of dead birds that are too old to be tested, if the personal disposal method listed above is not used.

Continued: http://culvercity.patch.com/articles/another-dead-bird-in-culver-city-tests-positive-for-west-nile-virus

Dead bird in Mendocino County tests positive for West Nile Virus

The first positive case of West Nile Virus in Mendocino County in recent years was reportedly found Tuesday, Mendocino County Public Health Services reported Friday.

A bird found in Inland Mendocino County tested positive for the virus Sept. 11, according to Public Health, representing the first positive case in "several years." No human cases of WNV have been found since September 2008, according to Public Health.

The virus is transmitted to humans and animals through a mosquito bite. Mosquitoes are infected when they feed on infected birds. Mendocino County Public Health Officer Dr. Craig McMillan recommends the following precautions to decrease the risk of contracting mosquito-borne diseases.

Avoid spending time outdoors at dawn and dusk, when mosquitoes are most active.

When outside, wear long pants and a long-sleeved shirt, and use insect repellent. Products containing DEET appear to be most effective.

Eliminate all sources of standing water that can support mosquito breeding.

Read on:  http://www.ukiahdailyjournal.com/ci_21548590/dead-bird-mendocino-county-tests-positive-west-nile