Riechel Reports - Events - City of San Bruno CA

San Mateo County Mosquito & Vector Control District
November 12 2020 Newsletter


Rain Returns to San Mateo County

As the wet weather of winter begins, our mosquito control strategy changes. During the summer, small amounts of urban runoff from irrigation and car washing accumulating in our stormwater system are a major concern. We also keep a close eye on our local creeks, which partially dry up in the summer, leaving small pockets of water where mosquitoes can develop. The season's first rain flushes out these sources, but creates different challenges for our mosquito control team.

In backyards across the county, items left outdoors over the summer begin to fill with water, providing plentiful habitat for mosquitoes. Kids' toys, leaf-clogged gutters, buckets, wheelbarrows, and empty flowerpots become nurseries for mosquito larvae. These sources are challenging for technicians to locate, since there can be dozens of sources in a single backyard. Rainwater also collects in seasonal impounds throughout the county. These natural water sources require regular treatment until they evaporate in late spring and early summer.

You can help out your technician by checking your own yard for items that can hold water after rain, and overturning or removing them. If you have outdoor water sources that can't be removed, you can treat them yourself with mosquito larvicides purchased online or from your local home improvement store. Not sure how to prevent mosquitoes around your home? Give us a call or request a technician visit online. We'd be happy to provide suggestions to keep you mosquito-free all year.

Learn more about our mosquito control program.

News
Holiday Office Hours
We will be closed on Nov. 26 and 27th in observance of Thanksgiving. More information.
Board of Trustees Meeting Schedule
There is no Board of Trustees meeting in December. The Board of Trustees will meet next on Wednesday, Jan. 13th. Board of Trustees meetings will be held remotely via Zoom until further notice. Download meeting agenda.
Mosquito Population Update
Culex pipiens was the most frequently collected adult mosquito in October, seen at a lower than average level this year compared to the five-year average. Culex erythrothorax continued to appear in above average numbers, but collections have declined from their peak in September.  In October, 53 larval samples were submitted to the laboratory. The most frequently occurring species in larval samples was Culex pipiens, the northern house mosquito, present in 33 of the 53 samples. Read more.
West Nile Virus Update
As of October 31, 2020, there have been 204 dead birds reported in San Mateo County. Of those, 62 have been suitable for testing and one has tested positive for West Nile virus (WNV). No mosquito samples or sentinel chickens have been confirmed positive for WNV in San Mateo County this year. In California, there have been 155 human cases of WNV from 21 counties, including seven fatalities. There have also been three human cases of St. Louis encephalitis virus (SLEV), from Madera, Fresno, and San Joaquin Counties. Read more.
Our Work by the Numbers
Things are finally slowing down after a very busy summer! In October, technicians responded to 258 service requests, including 53 reports of mosquitoes or standing water, 37 rodent inspections, and 131 yellowjacket or wasp nest removals. Read more.
'Tis the Season for Ticks

Here on the West Coast, we do things a little differently, and our ticks are no exception. Their life cycles follow a different schedule from their eastern cousins, with the peak season for adult Western Blacklegged Ticks (Ixodes pacificus) occurring in winter and early spring. This tick is the main vector for Lyme Disease in California.

If you look closely along local trails, you may see adult ticks perched precariously on the ends of twigs, leaves, or blades of grass. This behavior is called questing. Since ticks can't run, jump, or fly, they have to wait for dinner to arrive in the form of a person or animal brushing against them while passing by. The tick quickly grabs hold and comes along for the ride, crawling slowly over the animal's fur (or person's clothing) until it finds its way to the skin and locates an appetizing place to begin feeding.

Fortunately, this behavior makes it possible to avoid most ticks and almost all tick bites. Walking in the center of the trail and avoiding contact with trailside vegetation keeps ticks from hitching a ride. Wearing long sleeves and pants and tucking in clothing makes it hard for ticks to reach the skin, and using an EPA-registered repellent or treating clothing with permethrin adds another layer of protection.

When you get home from spending time outdoors, check your pets, your gear, and yourself for ticks. Putting clothing in the dryer for 15 minutes can kill any ticks you may have missed, and taking a shower will help you locate any ticks that may be hiding and rinse away any unattached ticks. You may want to get a family member to help you check places you can't easily see, like your back and behind your ears.

If you do get a tick, don't panic! Removing attached ticks promptly reduces your risk of being infected with any pathogens the tick might be carrying. Here's the safest way to remove a tick.

Malaria in California: A Short History

Many people may not know that there was a time, not long ago, when malaria was more than a disease you only worried about when traveling. Malaria is a mosquito-borne disease resulting from a parasite that causes fever, chills and flu-like symptoms that can progress to liver and kidney failure, or even coma and death in the worst cases. Malaria was brought into California in the early 1830’s by fur trappers from the Hudson’s Bay Company and quickly became endemic in California, where it was rampant throughout the gold rush and was considered to be a contributing factor to the loss of many native American tribes. In the early 1900’s, malaria was recognized as a mosquito-borne disease. The Mosquito Abatement Act of 1915 coupled with the establishment of many organized mosquito control districts facilitated the steady decline of cases in California

By the 1950’s malaria was no longer considered endemic in California, but there were still significant cases of locally acquired malaria every year boosted by the travel and movement of troops during the Korean War. In 1955 the 8th World Health Assembly launched the Global Malaria Eradication Campaign. The goal was to eliminate malaria from the world using a combination of indoor and outdoor pesticide applications, personal protection, and habitat modification, helmed by vector control agencies in every country.

While Vector Control no longer employs “scorched earth” techniques, we still believe in the importance of mosquito control as a way to prevent the spread of diseases. Every traveler returning from a malaria endemic region could potentially reintroduce diseases like malaria or dengue to a waiting population of mosquitoes. As the potential malaria vectors Anopheles hermsi, An. freeborni and An. punctipennis are present in the Coastal Region of California, the District laboratory is in the planning stages of a project to improve our knowledge of the distribution of these species.  This knowledge will help us develop better targeted approaches to travel-related introductions of malaria in order to prevent it from ever establishing again. Read more.


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Editor:  Robert Riechel       Contact      WEB:  www.PRRiechel.com       Copyright 2020