Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Shift in feeding behavior of mosquitoes sheds light on West Nile virus outbreaks

28.02.2006


Since its introduction to the United States in 1999, West Nile virus has become the major vector-borne disease in the U.S., with 770 reported deaths, 20,000 reported illnesses, and perhaps around a million people infected. The virus is transmitted by Culex mosquitoes (the “vector”) and cycles between birds that the mosquitoes feed on. Humans can also be infected with the virus when bitten by these mosquitoes.


A shift in the feeding behavior of Culex mosquitoes (their larvae amass in standing water, as seen above) helps explain the rising incidence of West Nile virus in North America. (Image: James Gathany, CDC)



Scientists have struggled to explain these large outbreaks in the U.S., which stand in stark contrast to the sporadic European infections. In a new study published in the open access journal PLoS Biology, Drs. Marm Kilpatrick, Peter Daszak, and colleagues now present evidence that the major vector of West Nile virus in the USA, Culex pipiens mosquitoes, change their feeding behavior in the fall from their preferred host, American robins, to humans, resulting in large scale outbreaks of disease.

These feeding shifts appear to be a “continent-wide phenomenon,” the researchers conclude, and may explain why West Nile virus outbreaks are so intense in the U.S. compared to Europe and Africa, where the virus originates.


From May through September 2005,Dr. Kilpatrick, senior research scientist with the Consortium for Conservation Medicine, and his team collected mosquitoes and caught birds at six sites in Maryland and Washington, D.C. They determined the changes in mosquito populations throughout the West Nile virus transmission season, the abundance and diversity of bird species at these sites, and tested samples for West Nile virus.

Dr. Kilpatrick says, “To find out which species mosquitoes favored as hosts, we collected thousands of Culex pipiens mosquitoes and selected those that had just fed and still had bloodmeals in them. We sequenced the DNA in the bloodmeal to identify the species of host they had fed on.”

Their findings showed that from May to June, the American robin, which represented just 4.5% bird population at their sites, accounted for more than half of Culex pipiens’ meals. As the summer wore on and robins left their breeding grounds, the probability that humans were fed on increased sevenfold. Because the overall number of birds increased during this time, Kilpatrick and his team concluded that mosquitoes changed to humans as a result of robin dispersal, rather than a lack of avian hosts. “This feeding shift happened, even though the total number of birds at our site increased as other species’ offspring joined the population,” said Kilpatrick.

With the data collected from the Washington, D.C., area, the researchers presented a model of the risks of infection of the West Nile virus in humans. The model predicted that the risk of human infection peaked in late July to mid-August, declined toward the end of August, and then rose slightly at the end of September. The actual human cases in the area that year, the authors point out, “showed a strikingly similar pattern.” This same pattern was seen in California and Colorado, with numbers of infected Culex tarsalis mosquitoes (the main vectors in the western USA) peaking in June and July, followed by a late-summer spike in human infections, suggesting a continent-wide phenomenon.

Dr. Peter Daszak, Executive Director of the Consortium for Conservation Medicine, comments: “This is a case study in how to understand emerging diseases. Our collaborative team includes ecologists, virologists, and entomologists, and uses state-of-the-art techniques, including DNA sequencing of mosquito blood meals, to piece together what drives a virus to cause outbreaks in people. At the CCM we study the ecology of diseases and develop predictive models that can help us prevent future outbreaks. We are now using this approach to help understand the emergence and spread of other viruses such as SARS, Nipah virus and avian influenza.”

The study is funded by the National Institute of Allergy and Infectious Disease.

Paul Ocampo | alfa
Further information:
http://www.plosbiology.org

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>