District Information

District Map

Click Here for West Nile virus Pamphlets

West Nile virus Information Pamphlet 2004

West Nile virus Information Pamphlet 2005

Click Here to Watch - West Nile virus

 

What is West Nile Virus?

West Nile (WN) virus is a mosquito-borne virus that has been found in parts of Asia, eastern Europe, Africa, and the Middle East. The virus was first detected in the United States (U.S.) in 1999 in New York City. The majority of people and animals that are infected with the virus have a mild illness or no symptoms. In rare cases, the virus can cause a more serious inflammation of the brain. The elderly are at a higher risk for disease caused by West Nile virus.

How Do People And Animals Get West Nile Virus?

WN 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 the 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. Humans and horses are incidental hosts for the West Nile virus. The virus is most prevalent from May to October when mosquitoes are most abundant.

 

What Are The Symptoms Of West Nile Virus In People?

Most 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 a few cases, the disease will progress to encephalitis (inflammation of the brain). The time between the mosquito bite and the onset of the illness, known as the incubation period, ranges from 5-15 days in in humans. It is estimated that 1 in 150 people who are infected with WNV will require hospitalization. The elderly are particularly susceptible to clinical illness caused by WNV. There is no specific treatment for infection with WNV, although supportive care is important.

Which Animals Get West Nile Virus?

An infected mosquito can bite any animal, but not all animals will become infected. The disease most often affects birds, but occasionally causes disease in other animals as well.

Birds:

Wild birds are the animals from which the mosquito vector primarily acquires the virus. Infection has been reported in more than 138 bird species. Although many birds that are infected with WNV will not appear ill, WNV infection can cause serious illness and death in some birds. The most severe illnesses are seen among the corvid birds, which include crows, jays, ravens, and magpies. American crows constitute the majority of the birds reported dead due to WNV.

Horses:

 Horses are also susceptible to WNV. The disease does not seem to be specific to a particular breed or age of horse. Clinical signs of disease consist of central nervous system abnormalities similar to those caused by infection with eastern equine encephalitis (EEE) and western equine encephalitis (WEE). EEE and WEE vaccines are available for horses and are recommended for use in the spring. An equine WNV vaccine is now also available.

West Nile Virus Prevention And Control

To decrease exposure to mosquitoes and the infections they may carry:

• Avoid outside activity at dawn and dusk during the mosquito season (May to October). This is particularly important for elderly and small children.
• Wear protective clothing (long pants and long sleeves) and apply insect repellant when outside.
• Make sure that doors and windows have tight fitting screens. Repair or replace screens that have tears or holes in them.
• Drain all standing water on private property and stock permanent ponds with fish that eat mosquito larvae.
• Make sure roof gutters drain properly. Clean clogged gutters in the spring and fall.

 

What Do I Do If I See A Dead Bird?

If you find a dead bird, particularly a dead crow or other corvid (e.g., jay, magpie, raven), please call the number below promptly. Do not touch the bird. DHS will record all dead bird reports and will arrange for pickup and laboratory testing for WNV when appropriate.

 

Dead Bird Surveillance and Contact Information:

 

West Nile Virus Dead Bird Surveillance Program

Division of Communicable Disease Control

California Department of Health Services

Toll Free Telephone: 877-WNV-BIRD

(877-968-2473)

Website: http://westnile.ca.gov

 

The Facts About Mosquitoes

• All Mosquitoes must have standing water to complete their life cycle.
• It only takes 7 days for a mature mosquito to develop from an egg during warm weather.
• Mosquitoes do not hatch in grass or shrubbery unless standing water lies beneath. Adults may be seen resting in these areas.
• Only the female mosquito bites. She uses the blood meal obtained in order to produce eggs. The male feeds only on plant juices and is incapable of breaking the skin.
• Mosquitoes may live as long as 3 weeks during the summer. They may live several months during the winter, surviving in protected areas to start a new generation in the spring.

The Disease Cycle

Over the course of history, mosquito vectored disease has been responsible for more human sickness than any other disease. The most common diseases in California cause encephalitis (brain swelling). The three most common forms are St. Louis (SLE), western equine (WEE) and West Nile virus (WNV). All these diseases are carried by wild birds. Infected birds are bitten by local mosquitoes that may transmit the virus to humans and horses if they are bitten.

Mosquito Imposters

How to Prevent Breeding

Since all mosquitoes require stagnant water for development, eliminating this source is the simplest and most effective action.

• For pools, operate filter or skimmer everyday to remove egg rafts and larvae. Remove rainwater from pool cover. Stock "out of order" pools with mosquito fish.

• Change water in animal troughs weekly.

• Dispose of unused containers that will collect rain or sprinkler water such as barrels, cans, jars, old tires, buckets, etc. Store desirable containers upside down.

• Stock ornamental ponds with mosquito fish.

 

Surveillance Method

EVS Trap

(Encephalitis Virus Surveillance Trap)

 

 

Click to watch: Ticks of Medical Importance

What are Ticks?

 

Ticks are insects in the Arachnid family, related to spiders. They attach to animals, pets, and people using complex mouthparts resembling a "harpoon". While they are attached, they suck blood for several days, dropping off once engorged.

How big are they?                  

Larvae and nymphs are about the size of a "." while adult ticks vary between a small "o" and a large "O".                                                                   

Where are they found?

Ticks live on or near the ground waiting for a host. they often climb onto tall grass or plants hoping to snag onto passing animals.

How do they find a host?

Tick have sensory organs in their legs that detect carbon dioxide, odors, and heat given off by warm blooded animals. They crawl to their host, they do not jump or fly.

Ticks and Disease

While many species of ticks exist, only a few are known to spread disease. The species of concern in our area is Ixodes pacificus or "deer tick".

Lyme Disease:

This is an infection caused by bacteria transmitted by the bite of certain ticks. The disease often starts as a circular skin rash around the area of the bite and can progress to more serious stages affecting joints, nerve, or heart tissue. Lyme disease has been reported in 47 states including California (mainly northern coastal area).

Ehrlichiosis:

Less common than Lyme disease, it is also spread by tick bites. One to three weeks after the bite fever, headache, and muscle aches develop. Fatigue and nausea may also occur. Both Lyme disease and Ehrlichiosis are treatable with antbiotics.

Other Diseases:

Rocky Mountain spotted fever, typhus, relapsing fever, tularemia, tick paralysis. These diseases are uncommon in California.

Preventing Tick Bites:

Ticks are most commonly encountered by people when engaged in outdoor activities such as hiking, camping, hunting, ect. Follow these recommendations to reduce your chances of bites when outdoors.

• Wear light colored clothing to spot crawling ticks.
• Apply insect repellant containing DEET following directions on the label.
• Check regularly for ticks when outdoors. Examine skin and scalp upon returning. Also inspect pets.

 

Tick Removal:

If a tick becomes attached, the best method for removal is to grasp the tick with fine tipped tweezers. Pull the tick away from the skin using a slow and steady motion. Do not grab the body as this may "squeeze" fluids from the tick into the opening. Use of substances such as petroleum jelly, finger nail polish, and matches are ineffective.

When to Call a Doctor:

• If unable to remove entire tick.
• If red "bull's-eye" rash appears.
• If fatigue or flu like symptoms occur.

 

Domestic flies, while often a nuisance, can also transmit germs to people. They are attracted to foul odors from garbage, sewage, manure, grass clippings, pet droppings, and decomposing animal and plant waste. Flies have hairy legs (pads) and most have sponging mouthparts (proboscis) allowing them to pick up and deposit germs and bacteria on food, open sores or cuts, drinking water, and cooking utensils.

Life Cycle

All flies undergo a developmental process called metamorphosis. This process consists of four stages. All developmental stages occur in moist and usually filthy areas containing decomposing animal or plant waste. In the warmer summer months, flies are able to complete their cycle in as little as 7 days. An adult housefly typically lives about a month and can lay almost 1,000 eggs, allowing for rapid infestation in unsanitary conditions. Most flies remain within a mile or two of where they emerge.

Prevention:

Fly control is most successful when breeding sources are eliminated since adult flies are harder to eliminate. The following tips can be used to reduce fly populations. These suggestions are divided into urban/suburban sources and commercial/ crop production.

Urban and Suburban
• Keep all garbage in containers with tightly fitting lids or sealed bags.
• Grass clippings should be composted or spread thin to allow drying. Remove twice weekly if possible.
• Pick up pet and animal droppings daily to avoid attraction and breeding. Dispose of in closed containers or keep buried.
• Rinse out trash cans often.

Commercial and Crop
• Keep manure dry and prevent from staying wet.
• Crop and animal processing waste should be composted or removed within seven days.
• Manure used as fertilizer should be mixed into dirt promptly.

Control-The Four S's
• Sanitation
• Screening
• Swatting
• Spraying

Sanitation:

Successful fly eradication in and around the home may involve all of the above. It is likely that the sanitation measures will effectively control your fly problem. However, if flies remain a nuisance, do the following.

Screening:

Make sure all windows and doors screens are tight fitting with no gaps. Placing mylar strips on screen doors or doors that open inward can dissuade flies from entering when opened.

Swatting:

The traditional fly swatter can still be effective against occasional flies that enter the home. Sticky fly traps and paper are also effective.

Spraying:

This involves the use of pesticides for control and should be used with caution. For indoor use, a non-residual pyrethrin or other spray should be used. When spraying outside, residual insecticides are most effective. Apply to surfaces where flies rest, around trash or other areas. Fly baits can be used but are only effective if good sanitation exists since baits can not compete with garbage. Fly traps are less effective and should be placed a minimum of 25ft from the residence. When spraying, remember: A Little Goes A Long Way and Always Follow Directions On the Label.