SAN JOSÉ, CALIF. – Beginning on May 05, 2014, the Santa Clara County Vector Control District (District) will launch a campaign to inform the residents of the city of Palo Alto about the risk of invasion by a severe nuisance mosquito species that can potentially transmit dangerous diseases; ask residents to report if bitten during the day by mosquitoes; and tell them about methods to prevent breeding mosquitoes in their backyards.
In August 2013, Aedes aegypti (aka Yellow Fever Mosquito) were discovered at the Holy Cross cemetery in a residential area of Menlo Park. The infested area is just across the border from the city of Palo Alto. Despite of the ongoing control efforts by the San Mateo Vector Control District and last winter's low temperatures, multiple detections show that the species is still present (see SMVCD's press release including a map of the infested area).
These mosquitoes are quite different than the native varieties. In addition to being day-biters, they are considered “container breeders” and require very little water to lay eggs and breed. Females will lay individual eggs next to the water surface in buckets, flower pots, and even trash and bottle caps. They will also lay eggs in natural containers such as tree holes, bamboo, and inside flowering plants such as bromeliads. The eggs can remain viable for years in the right environment and hatch once the eggs are re-flooded with water.
The diseases they carry are also different. The Aedes aegypti mosquitoes can transmit Dengue and Chikungunya viruses. They can also carry Yellow Fever. None of these diseases are currently being transmitted in California. These mosquitoes do not transmit West Nile virus (WNV).
Unlike WNV, which requires birds in order to increase, these diseases are transmitted in a human-mosquito cycle. While they are not currently being transmitted by mosquitoes in California, they are present here, and every year there are “imported” cases of Dengue detected in Santa Clara County and recently, an imported Chikungunya human case. Increased travel to and from places where these viruses are active increases the chances that local container breeding mosquitoes could begin passing them to humans.
Since late last year, the District has set up a series of mosquito traps near the border with the San Mateo County to detect any YFM activity. To date, none have been found. Having the mosquito in our county would bring the last factor needed for local transmission of these diseases. That is why we need the help of the public to report day-biting mosquitoes and take preventive measures.
Some practical measures against mosquito bites are:
•CALL AND REPORT if you see any small, fast black and white mosquitoes or if you are being bitten by mosquitoes during the day!
•DRAIN or DUMP standing water weekly since this is where mosquitoes lay eggs. Check items such as flowerpots and planter bases, toys, cans, leaky water faucets and sprinklers, rain gutters, buckets, pools, ponds, and old tires.
•Clean and scrub bird baths and pet-watering dishes weekly.
•Make sure your DOORS and windows have tight-fitting screens.
•Limit outdoor activities during DUSK & DAWN to prevent mosquito bites. Those are the times when the mosquitoes that transmit WNV are most active.
If you need to go outside in an area where mosquitoes are active:
•DRESS in long sleeve shirts and long pants, preferably of light colors.
•Apply insect repellent following label instructions.
Contact the Vector Control District if you are being bothered by mosquitoes or know of a potential mosquito-breeding source.
For free assistance on mosquito control, WNV, or other vectors, residents can contact the District office by calling (408) 918-4770 or fill out a service request online here.