West Nile Virus

For two days in the first week of February 2003, approximately 90 scientists from several different disciplines gathered at the Smithsonian Environmental Research Center, in Edgewood MD, to compile the information currently known about the wildlife side of West Nile virus, to establish priorities among the many future research needs, and to make plans for continued cooperation and collaboration. The West Nile Virus Wildlife Health Workshop was a first-of-its-kind undertaking.

The invited scientists included specialists in viruses, mosquitoes, diseases, and climate, scientists who mathematically model biological systems, and biologists who study birds, mammals, and alligators. They came from many colleges and universities, nonprofit organizations such as Audubon and the American Bird Conservancy, and federal agencies such as the U.S. Geological Survey, the U.S. Department of Agriculture, the Centers for Disease Control and Prevention, the National Park Service, and the U.S. Army. Those present acknowledged the power of this unprecedented merging of ecological, wildlife, and public health information. Financial support from Audubon greatly helped to make the historic meeting possible.

These dedicated and concerned scientists presented information from their own disciplines and determined the gaps in our knowledge that constrain our understanding of many aspects of the West Nile virus phenomenon. They identified the crucial data that are lacking and the types of research needed to collect those data. They prioritized the research needs so that the most pressing, basic data could be sought as funding is found.

Identifying which mosquitoes are capable of infecting which hosts,
Identifying (or statistically ruling out) other possible arthropod ectoparasites such as ticks, and
Examining the occurrence of host-to-host transmission, including that from mother to embryo and from prey to predator.

Included here also is the need to determine which host species are most vulnerable to infection, which ones are capable of passing on the virus, and details of the immune responses of different species. (For more information on WNV transmission cycles and infection: http://www.audubon.org/bird/wnv/pdf/the_virus.pdf)

2. Documenting and assessing the importance of the possible routes by which the virus is spread from one geographic area to another. Geographic spread may occur through short distance mosquito movement, short distance bird movement and dispersal, long distance bird migration, and possibly even long distance mosquito movement via transport vehicles such as trucks, boats, planes, and trains.

3. Determining the mechanisms by which the virus overwinters:

Can the virus remain dormant inside "healthy" birds or other animals during the winter, to rear up again later when conditions are more favorable for its subsequent transmission?
Do infected mosquitoes survive the winter and begin transmitting the virus in the following spring?
Can infected mosquitoes lay eggs that survive the winter and from which infected mosquitoes hatch the following spring?

4. Determining the actual impacts of West Nile Virus on wildlife populations. These data will be among the most difficult to obtain; there is no infrastructure in place in this country for the large scale collection and testing of dead birds, which would provide much needed data on the role played by WNV in avian mortality. The types of field studies of marked birds necessary for information on population effects (the percent and ages and sex of population members dying of WNV infection) are time- and labor-intensive, and are chronically under funded. As such, identifying appropriate on-going studies for possible future collaborative efforts will be an important component of this area of inquiry.

5. Assessing our ability to intervene successfully; to do so, we have to somehow safely interrupt the West Nile Virus transmission cycle.

Public education and outreach can potentially play a big role in reducing mosquito abundance; reducing unnatural mosquito breeding habitat - eliminating "backyard" sources of standing water - will limit the number of mosquitoes produced on a local level. (For guidelines as to eliminating sources of standing water: http://www.audubon.org/bird/wnv/pdf/what_can_i_do.pdf)
With regard to the control of living mosquitoes, much research remains to be done on the efficacy of different control methods on mosquitoes in different stages of their life cycles, and the possible negative short- and long-term effects of various pesticides on wildlife, human, and domestic animal health.
Development of animal vaccines for WNV might enable the protection of particularly vulnerable - threatened and endangered - populations and species experiencing crisis situations.

By the conclusion of the two-day workshop, the assembled scientists had determined the framework of the research responses necessary to effectively deal with this giant threat to wild and captive bird populations, and human health; a framework that will serve well for responses to future emerging human and wildlife diseases.

The actual slide presentations of speakers will be available in the near future; please check back.