Vector Control Collaboration Efforst Between Agencies in Two States

State: CA Type: Promising Practice Year: 2019

LHD Description

San Bernardino County is geographically the largest county in the contiguous United States. It covers over 20,000 square miles of land, and is located in southeastern California, with Inyo county to the north, Kern and Los Angeles Counties to the west, and Orange and Riverside Counties to the south. San Bernardino County is bordered on the east by the states of Nevada and Arizona. It has the fifth largest population in California, and is the twelfth most populous county in the nation. In 2017, San Bernardino County's population was estimated at over two million (2,160,256), with a projected growth of 28% between 2020 and 2045.

San Bernardino County is also racially and ethnically diverse. Approximately 21% of the population was born outside of the U.S., and approximately 42% of the population speak a language other than English at home. Over half (51%) of San Bernardino County residents are Latino. Among the remaining non-Latino residents, 31% are White, 8% are Black or African American, 6% are Asian or Pacific Islander, and 2% report two or more races. Less than one percent of residents are American Indian/Alaska Native (0.6%).

Public Health Issue

In 2003, West Nile Virus (WNV), which is transmitted by the bite of an infected mosquito, was detected in San Bernardino County. The arrival of WNV required a change in operations and surveillance techniques for the San Bernardino County Mosquito and Vector Control Program (SBCMVCP).  The surveillance techniques include trapping, identifying and testing mosquitoes; conducting door-to-door surveys; and utilizing sentinel chickens to identify possible mosquito-borne health threats in the areas being surveyed. The city of Needles, which lies on the western banks of the Colorado River, presented a special challenge during the peak mosquito season as the adult mosquito population was high and the number of potential water sources low. Causing uncertainty as to the source of these mosquitoes. Surveillance efforts in Needles resulted in positive WNV mosquito pools (50 mosquitoes per pool) and samples from sentinel chickens tested in the area. The technician assigned to the district which included the city of Needles, suspected the mosquitoes may be migrating from across the Colorado River into Needles. The issue was that the suspected breeding sources were located not only in another county, but rather in a different state Arizona, to which we had no authority or interagency agreements.  The high adult mosquito populations in Needles led to fogging two years in a row (2015-2016) to alleviate nuisance conditions and public health risk.

Goals and Objectives

The goal for this current practice was to collaborate with another agency in a different state and to use each other's resources to best protect public health. The main objective of the our agencies was to identify and abate the mosquito breeding sources in order to reduce the adult mosquito population, thereby decreasing nuisance conditions and the public health risk of a human WNV infection. 

Practice implementation/activities

In October 2017, the SBCMVCP Vector Technician II (VCT II) contacted the Mohave County Department of Public Health, Environmental Health Services Specialist (EHSS) in charge of vector services to discuss the issue at hand. The VCTII and EHSS started communicating to exchange information and collaborate to apply vector control management strategies that would reduce the health risk and enhance the quality of life for the residents of both counties/states. Information regarding surveillance and abatement efforts were shared by both counties starting in November 2017. A meeting was scheduled for May 24, 2018 for both county representatives to meet and discuss the strategies and efforts each county would utilize and the way data would be shared between them in order to determine progress.

For Mohave County, the meeting was attended by the County Public Health Director, Environmental Health Supervisor, EHSS, contracted Pest Abatement Manager, and the Federal Tribal Coordinator for the Fort Mojave Indian Tribe. For SBCMVCP the meeting was attended by the Program Coordinator, VCT II and the Disease and Surveillance Coordinator.

Having access to each other's surveillance data was beneficial as water sources were monitored and treated according to the specie specific breeding preference of mosquitoes trapped in both counties. This allowed for a more efficient approach investigating and subsequently abating mosquito breeding.

SBCMVCP kept the Needles City Manager informed of the collaboration and efforts being made by both counties to reduce the risk of mosquito-borne illnesses in the area which was then conveyed to residents.


As a result of joint surveillance data and monitoring Mohave County then increased their surveillance and abatement efforts in the agricultural fields directly across from Needles (eastern bank of the Colorado River). During the 2017 mosquito peak season (April October), As an apparent result of these actions SBCMVCP did not receive any mosquito complaints from Needles' residents and the counts of mosquitoes collected and tested were significantly reduced. Mohave County also reported a significant drop in complaints from residents. Neither County had any mosquitoes test positive for WNV for the 2018.

Needles MVCP Data





Mosquito Complaints





Number of Mosquitoes Trapped and Tested





Sentinel Chickens Tested Positive for WNV




No testing conducted

*the total number of complaints for 2015, 2016 and 2017 does not include the number of complaints received by the Needles City Manager's Office.

Public Health Impact

The outcome from this collaboration has allowed SBCMVCP and Mohave County to reduce the public health risk of mosquito-borne diseases and improving the quality of life for residents of both counties by reducing adult mosquito populations.

Website for SBCMVCP

Statement of the Problem/Public Health Issue

The abatement and surveillance efforts made by SBCMVCP in the city of Needles were showing improvement in reducing the adult mosquito population but were not enough to alleviate the nuisance being felt and reported by residents. 

Target Population affected and Population Reached

The population in Needles is 4,988 consisting of 78.9% White, 15.18% Hispanic, 2.02% Black, and 3.9% American Indian (Census 2016). Abatement and surveillance for 2018 was conducted every two weeks beginning March, 1, 2018 and ending October 31, 2018.

Past Procedures

In the past, SBCMVCP conducted regular abatement and surveillance efforts in Needles without access to the information of efforts being conducted by Mohave County in Arizona.  

Why is the Current/Proposed Practice Better?

The current collaboration between both counties has led to a significant decrease in the adult mosquito population, mosquito nuisance (complaints), and the elimination of fogging (adulticiding).

Is the Current Practice Innovative?

The current practice between the San Bernardino County (CA) and Mohave County (AZ) is innovative because it allowed two counties with different regulations, practices, and environment to work together to protect the residents of both counties from potential mosquito-borne threats. We are not aware of any other mosquito vector control agencies collaborating to reach a common goal in reducing the adult mosquito population.

Protecting Public Health

Mosquito borne illnesses are transmitted by the bite of an infected mosquito. Since 2015, there have been 124 reported human cases of WNV in San Bernardino County. The symptoms of WNV include headaches, body aches, joint pains, vomiting, diarrhea, or rash. About 1 in 150 people infected with WNV will develop serious illnesses that can affect the nervous system and lead to permanent disability and even death. As of now there is no vaccine for WNV.

The County of San Bernardino Department of Public Health Division of Environmental Health Services (DEHS) is dedicated to improving the quality of life for all residents and visitors by protecting public health, promoting safety and preventing environmental hazards. SBCMVCP is the program designated to enforce Health and Safety Code sections 2000 et seq and San Bernardino County Code 33.0941 et seq. SBCMVCP's priorities are continuously being evaluated in to order to ensure best practices and collaborations are being utilized in our daily operations and surveillance.  Public health and safety are always our first priority and we strive at providing the best services for the communities we serve.

The collaboration between San Bernardino County and Mohave County began in October 2017 and continues to exist.  The VCT II from SBCMVCP and EHSS from Mohave County communicate at least once a month to share program data and updates. The next in-person annual meeting is scheduled for May 2019.

The monthly exchange of information, provided both counties with the type of mosquitoes being trapped on a bi-weekly basis. Since each mosquito species has a special preference for breeding habitat, sharing the data of species trapped provided each county an idea of what type of habitat to treat in order to minimize mosquito breeding. This data allowed SBCMVCP to target specific areas for mosquito abatement activities.

The SBCMVCP not only received complaints from residents who call the program directly, but also from the City Manager's office who would be contacted by residents complaining of mosquito bites or high mosquito populations on their properties. For the peak mosquito season of 2018, SBCMVCP did not receive any complaints from residents or from the City Manager's office.

The stakeholders for this practice are the officials and residents for Mohave County, the Fort Mojave Tribe, and the city of Needles. This collaboration did not incur any extra cost to both Counties as the abatement and surveillance efforts were already part of the services provided in both counties. This collaboration has not required extra training nor additional workload for our technicians. In fact, this collaboration reduced the surveillance cost for SBCMVCP as the efforts in both counties provided more data and reduced the need for extensive trapping, abatement and complaint response.

The collaboration has assisted us in fulfilling our overall goal of improving the quality of life for all residents and visitors by protecting public health, promoting safety and preventing environmental hazards.

Data collection and analysis demonstrate the collaboration between Mohave County and San Bernardino County has been successful at reducing the adult mosquito population, thus reducing the public health risk of mosquito borne illnesses for the residents of both counties.

The collaboration evaluation results have been vital in achieving SBCMVCP goals and objectives.

Lessons Learned

Continuous efforts to collaborate with other mosquito and vector control districts, within and out of our state, are helpful for SBCMVCP to meet its goals of improving the quality of life for all residents and visitors by protecting public health, promoting safety and preventing environmental hazards. Regular communication and collaboration with other agencies, public officials and stakeholders is vital in achieving program goals.  

Partner Collaboration

SBCMVCP will continue to collaborate with Mohave County staff, city officials, neighboring vector control districts, the California Department of Public Health and the public. Our focus continues to be to find new innovative ways to achieve our goals.

Stakeholder Commitment to Sustain the Practice

SBCMVCP continues to hold share information and develop strategies with Mohave County staff and Needles' City Manager staff to find common goals and to leverage each others strengths in an effort to keep this engaged process successful.

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