West Nile Virus Public Health Update & Advisory - October 15-21, 2012

 

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Los Angeles County West Vector
& Vector-Borne Disease Control District6750 Centinela Avenue, Culver City CA 90230Ph: 310-915-7370 ext. 223; Fax: 310-915-9148Email: rsaviskas@lawestvector.org

 

West Nile Virus

Public Health Update & Advisory

 

October 15-21, 2012 

This is the weekly West Nile virus (WNV) update and public health advisory for the period of October 15-21, 2012 for all cities and unincorporated county areas within the Los Angeles County West Vector & Vector-Borne Disease Control District.  Cities and areas within the District are: Agoura Hills, Beverly Hills, Calabasas, Culver City, El Segundo, Hawthorne, Hermosa Beach, Hidden Hills, Inglewood, Lawndale, Lomita, Malibu, Manhattan Beach, Palos Verdes Estates, Rancho Palos Verdes, Redondo Beach, Rolling Hills, Rolling Hills Estates, Santa Monica, Torrance, West Hollywood, Westlake Village, and portions of Los Angeles City and Los Angeles County.

 

1.         Nationally: 

2012:   4531 Human Case; 183 deaths

2011:     712 Human Cases; 43 deaths (entire year)

 

2.         California: 

            2012:   301 Human Cases; 11 Deaths

            2011:   158 Human Cases; 9 Deaths (entire year)

 

3.         LA County: 

            2012:   100 Human Cases; 4 Deaths

            2011:     63 Human Cases; 4 Deaths (entire year)

 

4.         District & Other Local Areas within LA County (2012): 

            LA Co. West District:    7 Human Cases (0 new human cases for this period)

Antelope Valley:          10 Human Cases (0 new human cases for this period)

San Fernando Valley: 42 Human Cases (8 new human cases for this period)

            San Gabriel Valley:     32 Human Cases (5 new human cases for this period)

 

5.         New WNV Positive Indicators inside the District’s boundaries (10/8/12 thru 10/14/12): 

            (WNV indicators are positive dead birds, sentinel chickens, mosquitoes, or squirrels)

LA City:                       DB10): Zip 90064(3), 90049, 90025, 90019, 90066(2), 90049, 90045

                                    DS(1): Zip 90066

                                    SC(4): Zip 90094(2), 90008, 90036

Rolling Hills Est.:         MP(1): Zip 90274

Santa Monica:             DB(4): Zip 90403, 90404, 90405(2)

Culver City:                 DB(8): Zip 90230(4), 90232(4)

Beverly Hills:               SC(2): Zip 90210(2)

Inglewood:                   SC(1): Zip 90301

 

 

Types of Positives: 

 

(DB) Dead Bird(s):                  This is a dead bird tested for West Nile virus (WNV)

(MP) Mosquito Pool(s):           This is a group of trapped adult mosquitoes tested for WNV

(SC) Sentinel Chicken(s):       This is the testing of chickens housed in sentinel chicken flock coops 

distributed throughout the District designed to monitor WNV activity

(DS) Dead Squirrel(s):            This is a dead squirrel tested for West Nile virus (WNV)

 

 

What does it mean? 

 

Weather is an important factor in the spread of West Nile virus (WNV).  During the hotter summer months, mosquitoes can go from an egg to an adult in only 7 days. Since female mosquitoes can lay up to 400 eggs at a time, a single female mosquito can produce offspring that will generate over 8 million biting female mosquitoes in only 3 weeks. During the cooler winter months, the mosquito breeding cycle slows and can take as long as 3-4 weeks to go from an egg to an adult.  A wide variety of wild birds, including the American crow, are the reservoir for West Nile virus.  Mosquitoes become infected when they first bite an infected bird and then transfer the virus to other birds and humans as they bite again.  The virus is more active (virulent) in wild birds when the weather is hotter and conversely less active in birds during cooler weather.

 

Positive counts will decrease as the weather cools.  However, it can take some time before the decrease is reflected in the reporting data.  This is because there can be as much as a two-week incubation period before birds and/or humans show symptoms of WNV, and then another 7-10 days to run tests and confirm the positive results.  So as you can see, 3-4 weeks can elapse from the date the infection is acquired to the date it is reported.  Positive counts should begin to decrease by late October or early November.

 

The West Nile virus (WNV) human cases are over 600% higher nationally this year than 2011, 90% high in California than 2011, and 58% higher in Los Angeles County than 2011.  Also this year, unusually high and persistent hot weather and high humidity throughout Los Angeles County, and especially along the coast and coastal communities, have contributed to a significant rise in positive indicators (dead birds, sentinel flocks, mosquitoes, or dead squirrels) in comparison to 2011. Currently, 149 zip codes in Los Angeles County out of a total of 361 have recorded positive indicators for WNV for 2012.

 

The majority of positive indicators (dead birds, sentinels chicken flocks, mosquitoes, and dead squirrels) are dead birds. Birds routinely travel many miles from their nighttime nesting locations to feed and scavenger during the day before they return to their original location in the evening. Although positive birds collected in a specific area are significant with respect to trends on a wider basis, it does not definitively identify a specific city, zip code, or location as the site where the actual mosquito bite and infection occurred because of the birds extended daily travel patterns. A bird may travel and die as much as 1 to 10 miles away from the location where it was infected.  It is believed that a larger number of birds than usual are travelling further west this year to the coastal communities to seek relief from the unusual and persistent hot weather.

 

A positive result from sentinel chicken flocks and trapped adult mosquitoes are more specific with respect to the actual site of the infection, whereas positive dead birds are less specific with respect to the actual site of the infection.

 What should the city/county do? 

There is no specific action that is required by the city/county, but the District recommends that the city/county make this information known to their residents through their normal communication process so people walking or sitting outside at dawn, dust, or anytime during the night will take the appropriate precautions listed below to protect themselves from being bitten by infected mosquitoes.


Reporting  & Picking Up Dead Birds: 1-877-WNV BIRD (1-877-968-2473): 

 

The public is encouraged to report dead birds to help with West Nile virus surveillance and control efforts. Dead birds should be reported to the toll-free hotline number at 1-877-WNV BIRD (1-877-968-2473).  Dead birds must be less than 24 hours old to be able to test them for West Nile virus.  If the bird is rigid or decomposed, it cannot be used for testing.

 

Birds that are not in a condition to be tested can be disposed of in your normal weekly trash by taking the following steps: 1) Take a plastic garbage bag and inserting your hand in the open end; 2) Grab the dead bird and pull it into the garbage bag using an “outside-to-inside” pulling motion; 3) Tie off the bag with the bird inside and place it in your regular trash for disposal.

 

Please Note: The District does not pick up or disposed of dead birds that are not in a condition to be tested.  

  

Animal Control or your city should be contacted for disposal of dead birds that are too old to be tested, if the personal disposal method listed above is not used. 

 

Residents can protect themselves from WNV by doing the following: 

 

  • DEET - Apply insect repellent according to the label.  Repellents containing DEET, picaradin, IR3535, and oil of lemon eucalyptus are the longest lasting and most effective.  Repellents keep the mosquitoes from biting you.

 

  • DAWN AND DUSK - Mosquitoes that carry WNV primarily bite in the early morning and evening so it is important to wear repellent at this time.

 

  • MOSQUITO PROOF YOUR HOME - Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes.  Repair or replace screens with tears or holes.

 

  • DRAIN - Mosquitoes lay their eggs on standing water.  Eliminate all sources of standing water on your property, including flowerpots, old car tires, rain gutters and pet bowls. Ensure that swimming pools, spas, and ponds are properly maintained. If you have an ornamental pond, use mosquito fish. You can make an arrangement to pick up free mosquito fish at the District by calling 310-915-7370.

 

Symptoms of West Nile virus: 

 

People infected with WNV can experience a variety of symptoms that may include: no symptoms, West Nile Fever, or West Nile Neuroinvasive disease. Symptoms usually occur 2-15 days after infection.  If you suspect you have contracted WNV, consult your physician for testing and care.

 

 

Symptoms of “West Nile Fever” can include: 

• Headaches

• High fever

• Tiredness and body aches

• A skin rash and swollen lymph glands

 

These symptoms may last from several days to several weeks.

 

Symptoms of “West Nile Neuroinvasive Disease” can include: 

• Severe Headache

• High Fever

• Stiff neck

• Stupor

• Disorientation

• Tremors, convulsions, muscle weakness

• Paralysis

• Coma: This can also lead to long lasting and/or permanent damage to the brain. 

 

For mosquito problems or to pick up mosquito fish (1-310-915-7370):  Call 1-310-915-7370 Monday through Friday, 8:00 a.m. – 4:00 p.m.

 

For additional information on WNV and the Los Angeles County West Vector & Vector-Borne Disease Control District (www.lawestvector.org):  Please visit the District’s website at www.lawestvector.org.  WNV results and new positives are updated on a weekly basis.

 

Questions:  If you have any questions, please contact Robert Saviskas, Executive Director, at (310) 915-7370 ext. 223 or at rsaviskas@lawestvector.org.

 

 

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