DON'T FALL VICTIM TO LYME DISEASE

The underside of a Western black-legged tick is viewed under a microscope

 Fall is prime time for ticks and because many people like to hike or trek across Bay Area trails during this time of year, there is a higher likelihood of encountering ticks over the next several weeks.  It's important, particularly during fall and winter when adult ticks are more active, to take the steps necessary to reduce the risk of Lyme disease in Contra Costa County.
 

First, stay on cleared trails and avoid areas where ticks are commonly found, which include tall grass and tall, dense vegetation. Ticks do not jump or fly; they quest-- lying in wait on a tall blade of grass or shrubbery with their top legs stretched out so they can simply attach themselves to a person or animal when they brush against the foliage. The tick then crawls to a warm, moist place on the body where it can feed on blood, like the back of the neck or between the toes.
 

To discourage ticks from accessing the body, hikers should wear long sleeves tucked into their pants, and long pants tucked into their socks. Wearing light colored clothing makes it easier to see the dark ticks when they hitch an unwelcome ride. For people who enjoy camping or hiking off designated paths, repellents are available to ward off ticks. Some repellents should be applied directly to clothing prior to use, while other repellents are applied directly to the skin. Often, the same repellents used for mosquitoes are appropriate for ticks. Be sure to read and follow the product's label instructions for use and application.
 

Contra Costa County is home to three primary species of ticks: the Western black-legged tick (Ixodes pacificus), the Pacific Coast tick, and the American Dog tick, but only the Western black-legged tick is known to transmit Lyme disease. On average across California, 1 to 2 percent of adult Western black-legged ticks test positive for the bacteria that causes Lyme disease; however, state public health officials warn percentage rates can vary and tend to be higher in mountainous areas. The District's most recent surveillance of ticks concluded that

 1-2 percent of Western black-legged ticks are infected with the disease, the same as the state's average infection rate.
 

Regardless of the low infection rate, it is very important for people who conduct outdoor activities in wooded areas or in locations with thick vegetation to always do a tick check at the end of that activity. To remove a tick, use tweezers as close to the skin as possible, and gently, but firmly pull the tick straight off the skin. Once the tick is removed, place the tick in a Ziploc™-style bag with a damp cotton ball and drop it off or mail it to the District. The District's laboratory staff will identify the tick free of charge. If it is a Western black-legged tick, the District will notify the person who submitted it and provide a list of laboratories that, for a fee, will test the tick for Lyme disease.

Lyme disease is a potentially serious sickness. Now is the time to prevent exposure to ticks and reduce the risk of Lyme disease. 

CHANGING SEASONS

 As the days grow shorter and the temperatures start to cool, it is clear fall is here. And that's a welcome change for Contra Costa Mosquito and Vector Control District employees because fall typically spells the impending end of West Nile virus season. The two primary species of mosquitoes that can transmit West Nile virus in Contra Costa County enter a type of hibernation in the cool months and the virus itself needs warmer temperatures in order to thrive, so the risk of both the virus and the number of mosquitoes that can transmit the virus substantially decreases once fall weather arrives.
 

The end of 2014's West Nile virus season is an especially welcome occurrence. This year California experienced the highest level of West Nile virus in its history. In Contra Costa County,  25 groups of mosquitoes have tested positive for the disease thus far in 2014; the largest number to be confirmed in the county since 2008. And with a large number of infected mosquitoes that are just one bite away from infecting people, the District has had to work even more quickly to protect public health.

The District's overall approach to preventing mosquito-borne illnesses is to practice Integrated Vector Management that focuses on long-term prevention of pests or their damage through a combination of techniques, such as biological control, habitat manipulation, modification of cultural practices, chemical control, resistance management, and public education. The majority of the District's efforts emphasize ways to prevent mosquitoes, in part, by eliminating water where mosquitoes could lay eggs because all mosquitoes must start their lives in water. In cases where the water cannot be removed, the District's trained and certified employees use biological control such as mosquito-eating fish or bacterial larvicides to kill young mosquitoes before they have a chance to develop into adult mosquitoes capable of spreading disease. The District's public affairs staff work to educate the public about ways to reduce the number of places where mosquitoes could develop from egg to adult on private property. But when, in spite of all of these efforts, adult mosquitoes do emerge, the District follows scientific protocols to reduce the number of mosquitoes so that they are less likely to impact people. 

As part of the protocol, the District conducts surveillance and traps mosquitoes for testing to determine if they are infected with West Nile virus. When trapped mosquitoes test positive for West Nile virus, the District's protocol and mission to protect public health often requires quick action to kill adult mosquitoes and prevent human infection. The preliminary trapping provides primary data to direct the District's response. When the response is to use public health pesticides, applied most often by using an ultra low volume truck-mounted sprayer, the District's trained and certified technicians use botanical insecticides (plant derived compounds) or synthetic versions, including pyrethrins and synthetic pyrethroids combined with piperonyl butoxide. All of the products are registered with the Environmental Protection Agency for use in mosquito control and are applied according to label directions. People located in the spray zones do not need to do anything special due to the spraying. The District uses pesticides registered with the Environmental Protection Agency specifically for protecting public health.

"In some cases, the time between surveillance, testing and spraying a public health pesticide can be very short because the District relies on real time data about mosquito populations, infection rates and weather conditions that can affect spray operations," said the District's Scientific Program Manager, Steve Schutz, Ph.D.

"Once we understand there is a health risk to our residents, we need to respond quickly; sometimes within hours of analyzing the data, so that we can take the appropriate action before the mosquitoes can disperse or the conditions required to control them change."

When fogging for adult mosquitoes is concluded, the District's public health inspectors set traps again to determine whether the operation was successful in reducing the number of mosquitoes and infection rates. In 2014, the District fogged a total of 15 times in six communities; more than the seven times in five communities in 2013. The primary reason for the increase is the drought which causes environmental changes and leads people to unwittingly create water sources. For example, once flowing creeks and streams can become stagnant or reduced to multiple puddles. Those limited water sources attract birds which may be infected with the virus as well as mosquitoes that can bite them and then transmit the disease to people. In addition, some people store water in un-screened backyard containers or don't maintain their swimming pools which create perfect places for mosquitoes to lay eggs. 

As the current weather indicates a change in seasons, it brings hope of rain that could refill streams and creeks and once again provide natural mosquito control because mosquito eggs and larvae can't survive in water that is flowing or agitated.
 

 For more information or to sign up for automated email notification of the District's scheduled spray operations, please visit the District's website.