Aedes mosquito causes 41.4 percent vector control assessment increase

The presence of the Aedes mosquito which transmits Zika and other viruses will cause the county’s vector control benefit assessment to increase by 41.4 percent over the Fiscal Year 2016-17 rate.

The San Diego County Board of Supervisors, who serve as the board of the county’s Vector Control District, voted 5-0 June 21 to increase the annual assessment per equivalent dwelling unit from $5.00 to $7.07 while also approving the engineer’s report which addresses services to be funded during Fiscal Year 2017-18 and those costs.

The vector control assessment is in addition to a service charge which remains at $3 for the coastal region and $2.28 for the suburban and rural regions. Both the vector control benefit and the service charge are part of a landowner’s property tax bill.

“The county has seen a 39 percent increase in requests for service over the last three years,” said Supervisor Bill Horn. “The bump in fees means we can continue to provide the highest level of service possible to our residents.”

The primary goal of the Vector Control Program, which is administered by the county’s Department of Environmental Health (DEH), is to prevent vectors from reaching public nuisance or disease thresholds by managing vector habitat and preserving habitat values for vector predators and other beneficial species.

The Vector Control Program functions include early detection of public health threats through comprehensive surveillance, protection of public health by controlling vectors or exposure to vectors, and timely responses to customer service complaints or other requests.

The California Health and Safety Code defines a vector as any animal capable of transmitting an agent of human disease or producing human discomfort or injury. Vectors include mosquitoes, flies, gnats, mites, ticks, rodents, bats, and other small insects and vertebrae. Gophers, which can damage yards but do not directly threaten human health or comfort, are not considered vectors.

The Vector Control Program identifies vector species, recommends techniques for their prevention and control, and anticipates and minimizes any new interactions between vectors and humans.

The service charge was adopted in 1989 and was originally $3.80 per property. In 1995, that assessment was reduced to its current rate while the three regions were established to address differing service levels. In 2003, the county adopted its West Nile Virus Strategic Response Plan which won awards from both health and government organizations but which reduced the level of effort against other vectors and depleted the Vector Control Program reserves. Hantavirus and plague monitoring were reduced by 75 percent, and in 2004 the county’s first hantavirus case was discovered in Campo.

Rather than seeking additional funding only to restore the previous levels of activity, a larger assessment for an enhanced program was proposed and subsequently approved by the county’s landowning voters in 2005. The voters approved a maximum rate of $8.55 per single-family equivalent with allowable annual increases based on the San Diego Area Consumer Price Index but no more than five percent per year (for 2017-18 the maximum authorized assessment is $11.04 per single-family equivalent). The $8.55 additional assessment raised $9.5 million for the program including $2.3 million in one-time costs.

Factors which determine the annual rate include expenditure needs, rollover revenue (money not used in the previous year due to cost savings), and trust fund income. The rate was reduced to $6.36 for 2006-07 and to $5.92 for the following three years.

A decrease in rollover revenue and lower interest rates which reduced trust fund income forced an increase to $6.20 for 2010-11, but a reduction in seasonal staff due to favorable climate conditions allowed the rate to be lowered to $5.86 for 2011-12. The $5.86 rate was retained through 2014-15, and the development of efficiency processes along with the completion of specific phases of programs allowed for a reduction to $5.00 for 2015-16.

The assessment covers all properties in San Diego County including those in the county’s 18 incorporated cities and those owned by government agencies. A single-family home is assessed the base rate, agricultural property with a house is assessed the base rate plus nine cents per acre, and agricultural property without a house is assessed the base rate per 100 acres.

The enhanced program allowed for increased Vector Control Program staff, surveillance to detect plague and hantavirus, tick testing, and mosquito traps. Aerial applications were expanded from 27 sites in 2005 to 42 sites in 2007, potential breeding sources were treated monthly, and approximately 1,400 known breeding sites are now monitored and treated.

Public education for burrow dusting and plague was expanded. The average response time was reduced from eight to three days and field responses were provided for all rat complaints. The Vector Control Program also developed a rat starter kit and implemented on-line reporting of dead birds.

The Aedes mosquito transmits dengue and chikungunya as well as Zika. The first Aedes mosquito detected in San Diego County was found in October 2014, and the Aedes aegypti and Aedes albopictus species have both been found in San Diego County.

Aedes mosquitoes were detected in 16 of the county’s ZIP codes during 2015 and in 35 ZIP codes in 2016. Since October 2014 the county has had 270 confirmed or suspected travel-related cases of mosquito-borne illness which required field investigations including 213 in Calendar Year 2016.

Ten of those 2016 investigations required use of adult mosquito control. If Aedes mosquitoes or larvae are found in an area near a confirmed case, the Vector Control Program conducts chemical control for adult mosquitoes and larvae control if necessary while providing outreach and education to occupants within a 150-yard radius.

Educational materials are now available in English, Spanish, Vietnamese, Tagalog, Arabic, and Mandarin, and bilingual teams explain the response protocol and answer any public questions at least 48 hours before treatment as well as during treatment.

San Diego County is also still experiencing West Nile Virus cases, and the overall workload of the Vector Control Program has increased by 20 percent since October 2014 while the number of complaints or requests for service increased by 39 percent. The Department of Environmental Health had 5,385 requests during Fiscal Year 2014-15 and 8,238 during 2015-16. DEH had 7,963 requests between July 1, 2016, and June 6, 2017, and projects more than 9,000 requests during Fiscal Year 2017-18.

Although the known breeding sources have been treated monthly between March and October, the recent mild winters necessitate the extension of inspection and treatments during November through February due to observed mosquito breeding, and the monitoring and treatment during the additional four months has increased staff hours by 11 percent over 2014-15.

Mosquitoes which can transmit West Nile Virus prefer large stagnant bodies of water such as creeks, rivers, and pools for breeding, but Aedes mosquitoes are found in urban areas and prefer to breed in very small sources of water such as plant saucers, which may be found in homes or yards.

The Vector Control Program has added larvacide treatment of areas impacted by high tides, defined as a tide higher than six feet, within 48 hours of the end of the tidal event. That program reduces the risk of mosquito breeding in lagoons and surrounding areas which could hold water after a tidal event.

The assessment increase will allow for an addition of 7.0 staff years. The 2017-18 Vector Control Program will have a $10.9 million budget funded by $6.5 million from the benefit assessment, $2.5 million from the service charge, a $1.8 million fund balance, and $0.1 million of interest income and contracts to perform work for other county departments or districts.

The expected expenditures are $6.2 million for salaries and benefits for permanent staff and seasonal workers, $3.1 million for services and supplies including larvacides, aerial applications, and outreach materials, $1.0 million for transportation and equipment expenses, and $0.6 million of external overhead and other incidental costs.

The program’s $8.7 million budget for 2016-17 was obtained from $4.6 million of benefit assessment collections, $2.5 million from the service charge assessment, and $1.6 million of trust fund balance. The 2016-17 expenditures consisted of $5.1 million for salaries and benefits, $2.7 million for services and supplies, $0.5 million for external overhead and other incidental costs, and $0.4 million for transportation and equipment.

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