United States
 Protection Agency
    Protect Yourself
  Wear long sleeves and
  pants, especially when
  near stagnant or
  polluted water.

  Be mindful of
  mosquito activity,
  which peaks at dusk
  and dawn in summer

  Consider using
  mosquito repellants, if
  necessary, that
  contain  DEBT.
  Broadleaf arrowhead
West Nile Virus (WNV) first appeared in the United States in
1999. Since its inital outbreak in New York City, the virus
has spread across the country from East to West. Female
mosquitoes transmit the virus primarily by infecting
birds. Occasionally, mosquitoes transfer the virus from
birds to humans, most of whom experience no
symptoms. One out of five infected people develop West
Nile fever, characterized by mild, flu-like symptoms.
Infection can sometimes, although rarely, be fatal for
humans. Since West Nile is lethal in some bird species,
unusual bird deaths may signal human outbreaks.
Are Wetlands a  Threat?
      Healthy wetlands are not uncontrolled
      breeding grounds for mosquitoes.
Healthy wetlands sustain numerous species of
mosquito-eating fish, amphibians, insects and
birds, all of which help limit mosquito

The principal mosquito carrier of West Nile
virus on the East coast, Culexpipiens, does
not prefer to reproduce in most wetlands.
These species reach greatest numbers in large
urban centers, breeding easily in artificial
containers—birdbaths, discarded tires,
buckets—and in human-created environments,
such as clogged gutters, animal waste lagoons
and sewage effluent. Adapted to polluted
habitats, these Culex species generally avoid
 Disease  Transmission
 Mosquitoes are the primary vectors of West Nile, meaning they carry
 the virus from host to host. While nectar is their primary food source,
 females take blood in order to develop their eggs. Mosquito activity is
 reduced in colder months, but the virus may still  persist in dormant
 mosquitoes and eggs that survive winter.

 The Centers for Disease Control and Prevention (CDC) reports that 43
 mosquito species in the United States have tested positive for West Nile
 virus. The most common carriers are the House mosquito (Culex
 pipiens) on the East coast and Culex tarsalisin the West. Because it
 readily feeds on  humans, Culex salinarius is also an important vector.

 Since mosquitoes primarily infect birds, unusual  bird deaths may signal
 a WNV outbreak and should be reported to appropriate local, county or
 state agencies. Based on analysis of 2001 and 2002 data, the CDC
 reports that counties that report WNV-infected dead birds early in the
 transmission season are more likely to report subequent WNV disease
 cases in humans.
swamps and salt marshes altogether.

Damaged or degraded wetlands can provide ideal
habitat for some mosquito species that carry West
Nile. Excess nutrients in contaminated waters can
spur microbial growth and cause harmful algal
blooms, which feed mosquito larvae. Filling or
draining wetlands may also increase mosquito
outbreaks, as an altered  landscape with stagnant
pools of water may no longer contain mosquito

Sometimes, even healthy wetlands may harbor
large numbers of mosquito species that carry
WNV.  Unlike Culex pipiens, Culex tarsalis, the
major WNV vector in western states, prefers to
breed in clean water. Therefore, it may be
necessary to use appropriate mosquito  control
measures to prevent  WNV disease transmission.
                                              Culex pipiens (House mosquito)
                                              Culex pipiens is the primary West Nile vector in the
                                              eastern  United States.  It can be found in urban and
                                              suburban settings, has a flight range of 1/4 to 1 mile and
                                              prefers to breed in standing water, especially in water
                                              polluted with organic matter.

                                              Culex salinarius
                                              Found in fresh and saltwater marshes, lakes and ponds,
                                              Culex salinarius also prefers artificial containers around
                                              human residences and businesses. Because it readily
                                              feeds on humans, evidence indicates that it may be
                                              responsible for transmitting West Nile to people.

                                              Culex tarsalis (Western Encephalitis mosquito)
                                              An abundant mosquito in Western States, it breeds
                                              primarily in irrigated agricultural areas and  in temporary
                                              or seasonal depressions. It is most active at dusk and
                                              feeds on humans, domesticated animal and birds.  It is the
                                              primary vector for West Nile in the midwestern and
                                              western states.


Protect Your  Home & Community

     Eliminate stagnant water
     Limit the number of places available for
     mosquitoes to lay their eggs by
     eliminating standing water sources from
     around your home (e.g., tires, garden pots
     and bird baths).
            \                /
          Protect wetlands from pollution
          Including runoff from farms, lawns
          and roads with buffers, since
          contaminated water attracts

             Check Stormwater Systems
             Ensure that stormwater
             catchments and constructed
               etlands are properly designed
             and maintained.

             Install Screens
             Install or repair screens on doors
             and windows so that mosquitoes
             cannot get indoors.

          Consider Using Pesticides
          If necessary, try larvicides before
          adulticides, since larvicides more
          effectively control mosquitoes.
          Carefully follow instructions on the
          pesticide's label.
                                  Wetland Restoration
       and Mosquito  Reduction in  New Hampshire
Prior to its restoration in 1999, the two-acre Edmond Avenue wetland
was in critical condition. Residential development near Portsmouth,
New Hampshire, had partially filled the wetland, and urban and
stormwater runoff had contaminated the water. Increased sedimentation
                               had reduced the extent of open
                               water, and invasive plants choked out
                               native species.

                               By 1996, the continued degradation
                               of the Edmond Avenue wetland
                               transformed the ecosystem into a
                               major breeding site for mosquitoes,
                               including the Culex species primarily
                               responsible for West Nile
                               transmission. During 1996-1999, the
                               application of mosquito larvicides
and sprays jumped to 4-5 times per year, a four-fold increase from the
previous 15 years. Since its restoration in 1999, the Edmond Avenue
wetland no longer requires mosquito
control measures. The restored
wetland lacks stagnant depressions
and is deep enough in some areas to
support fish that eat mosquitoes.
Wave action also disrupts mosquito
breeding. Results have been
astonishing—a near 100% reduction
in mosquito habitat and the virtual
elimination of Cu7exspecies, not to
mention improved water quality and
bird habitat.
Degraded wetland - shallow,
stagnant pools harbor many