West Nile Virus Update
As of October 30, 2013, there have been 2,059 human cases of West Nile Virus (WNV) (including 83 fatalities)
reported nationally to the Centers for Disease Control and Prevention. Approximately 49% of the human cases
were classified as West Nile neuroinvasive disease (i.e. meningitis or encephalitis). The remaining cases (51%)
are the less severe form of the disease, West Nile fever. Human cases of WNV were reported from states nationwide.
States with the highest number of human cases of WNV include California, Colorado, Nebraska, North Dakota, South
Dakota and Illinois.
So far this year, California has had 319 human cases of WNV. Eleven of those were in San Bernardino County, one
of which resulted in a fatality. Human cases in San Bernardino County have remained low compared to the state average.
West Nile Virus Dead Bird Hotline Update
Live operators no longer answer the WNV Dead Bird Hotline. As of October 19, 2013, calls made to
the WNV Dead Bird Hotline will be directed to
report dead birds online. Those not able to enter
a report online will be given the option to enter their zip code and be referred to their local
vector control agency. Vector control staff can assist entering the dead bird report. Please visit
the California West Nile Virus website for more information.
New Mosquito Species Documented
Two new types of mosquito have been found in California. The Asian Tiger mosquito (Aedes albopictus
been found in Los Angeles County, and the Yellow Fever mosquito (Aedes aegypti
) has been found in Fresno,
Madera and San Mateo Counties. Though common in other parts of the world, they had previously not been
identified here. These mosquitoes were probably introduced by hitchhiking in freight containers on cargo
ships or by air. Both types of mosquitoes can carry WNV but can also spread diseases such as dengue,
yellow fever, and Chikungunya. Most mosquitoes in San Bernardino County bite at dawn and dusk, but the
Asian Tiger mosquito and Yellow Fever mosquito can bite at any time of day.
For the first time in San Bernardino County, the Dark Rice Field mosquito (Psorophora columbiae
identified in Needles after the monsoon rains that occurred this summer. When flooded, large numbers of
these mosquitoes develop quickly and can resemble a dark cloud. The Dark Rice Field mosquito is distinguished
by its dark and silver coloring and can be found in fields, yards, and some wooded areas. Similar to the Asian
Tiger mosquito and Yellow Fever mosquito, the Dark Rice Field mosquito can bite at any time of day, but
prefers the early morning and late afternoon.
If you or anyone you know are being bitten during the daytime, please report it to your local vector
control agency and save the specimen for identification if possible. You can find your local vector
control agency here
How Can I Help Prevent West Nile Virus?
To aid in the prevention of WNV, it is very important that property owners remove all sources of stagnant
water from their property. San Bernardino County residents with pools are urged to keep them properly
maintained. Mosquitoes breed in stagnant water and green pools in very large numbers.
Click here to download a brochure with more important facts on WNV prevention. If you’re a senior,
click here to download a brochure with information about how to keep yourself safe from WNV.
You can report dead birds or squirrels to the California West Nile Virus website at,
For more information or to report a green pool or mosquito breeding source, contact the Division of
Environmental Health Services at (800) 442-2283 or visit our website at www.sbcounty.gov/dph/dehs.
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Follow our social media sites to get the latest news on mosquito and vector control, food safety and
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and YouTube en Español.
If you have any questions or comments, please contact Lana Cao, Health Education Specialist I,
at 800-442-2283 or Lana.Cao@dph.sbcounty.gov.