Counts of human cases of West Nile
Virus by County as well as Counts of cases in horses,
dead bird counts, and sentinel mosquito samples,
sentinel chicken flocks and squirrel cases updated
regularly are available
California's West Nile Virus Website
West Nile Virus activity
in the Yuba-Sutter region has started. There are
positive mosquito pools and WNV-positive dead birds
found in both counties. There will be no more bird
pick-up for Yuba County; however, please
continue to report dead birds by calling
(1-877-968-2473) or by going
here to report online. Reporting dead birds
will help the state in mapping WNV hotspots in
Please be reminded to
continue protecting yourself from WNV by applying
mosquito repellent with DEET, avoiding the outdoors
during dusk and dawn and emptying out items with water
where mosquitoes can breed. For the latest updates regarding West Nile Virus
activity in California, please visit
California's West Nile Virus website.
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Frequently Asked Questions (FAQs)
1. What is West
Nile Virus (WNV)?
2. How do people
and animals get West Nile Virus?
3. What are
symptoms of West Nile Virus in people?
4. How soon do
infected people get sick?
5. How can you
minimize the risk of WNV infection?
6. How is WNV
detected and monitored in California?
1. What is West Nile Virus (WNV)?
West Nile virus (WNV) is a mosquito-borne disease that
is common in Africa, west Asia, the Middle East, and
more recently, North America. Human infection with WNV
may result in serious illness. Experts believe WNV is
established as a seasonal epidemic in North America that
flares up in the summer and continues into the fall.
2. How do people and animals get West Nile Virus?
West Nile Virus is transmitted to people and animals by
infected mosquitoes. Only certain species of
mosquitoes carry the virus and very few mosquitoes are
actually infected. A mosquito first acquires the
infection by feeding on a bird with virus in its blood.
The virus lives in the mosquito and is transmitted to a
new host in the mosquito's saliva when the insect bites
a person or animal. Human-to human transmission of WNV generally does not occur. West Nile Virus can
also be transmitted via blood transfusion, transplants
or mother to child. All donated blood is checked
for WNV before being used. The risk of getting WNV
through blood transfusions and organ transplants is very
small, and should not prevent people who need surgery
from having it. Transmission during pregnancy from
mother to baby or transmission to an infant via
breastfeeding is extremely rare.
What are symptoms of West Nile Virus
people who are infected with WNV have no symptoms
whatsoever. However, of those who become ill,
symptoms can include fever, headache, nausea body aches,
mild skin rash, or swollen lymph nodes. In few
cases, the disease will progress to encephalitis
(inflammation of the brain). The time between the
mosquito bite and the onset of illness, known as the
incubation period, ranges from 5-15 days in humans.
4. How soon do infected people get sick?
People typically develop symptoms
from 3 to14 days after they are bitten by an infected
How can you minimize the risk of WNV
decrease exposure to mosquitoes and the infections they
spending time outside when mosquitoes are most active,
especially dawn and dusk
outdoors, wear long pants, long sleeve shirts and other
insect repellant, preferably with DEET, according
to label instructions
sure that doors and windows have tight fitting screens.
Repair or replace screens that have tears and holes.
all sources of standing water on your property that can
support mosquito breeding
your local mosquito and vector control agency if there
is a significant mosquito problem where you live or
is WNV detected and monitored in California?
California is well prepared to
detect, monitor, and respond to WNV through ongoing
collaboration between over 100 public agencies. The
California surveillance system includes human and horse
case detection and testing of mosquitoes, sentinel
chicken flocks, and dead birds for WNV.
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