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.
Results/Outcomes
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 |
| 2015 | 2016 | 2017 | 2018 |
Mosquito Complaints | 28 | 37 | 22 | 0 |
Number of Mosquitoes Trapped and Tested | 647 | 4,523 | 559 | 469 |
Sentinel Chickens Tested Positive for WNV | 0 | 2 | 0 | 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
www.sbcounty.gov/dph/dehs