Arbovirus Emergencies

Arbovirus (mosquito transmitted diseases): Mosquitoes have both positive and negative impacts on the environment. Mosquitoes provide a food source for fish and other aquatic organisms. They are also food for bats, birds, spiders, and dragonflies. However, they transmit pathogens that cause many harmful diseases, including malaria, encephalitis, yellow fever, dengue fever and the latest mosquito virus to reach the USA, West Nile Virus. The vector mosquito species (the species of mosquito that can transmit a particular disease) for Malaria, Saint Louis Encephalitis (SLE), Western Equine Encephalitis (WEE) and West Nile Virus (WNV) already exist and are active here in Washington. West Nile Virus (WNV) is an encephalitis virus that is closely related to Saint Louis Encephalitis. It is important to note that there are a number of mosquito species that can vector (transmit) West Nile Virus and the state of Washington and Franklin County has a large numbers of these species present in abundant populations.

The primary mission of the FCMCD is to protect the public health and safety of those in the FCMCD and has set the following arbovirus protection provisions for this Mosquito Control District area:

1. Adult Mosquito Surveillance/Monitoring
2. Adult Mosquito Collection Virology Testing
3. Mosquito larvae prevention: Eliminating/modifying mosquito breeding habitats
4. Mosquito larvae prevention: Control of mosquito larvae in their aquatic habitats
5. Adult mosquito intervention: Air space spraying of Ultra low volume applications of mosquitocides to control adult mosquito activity.
6. Alerts and declaration of Arbovirus Emergency: From the Washington State Department of Health
7. FCMCD Guidelines for the Phased Response to Arbovirus Emergencies
8. FCMCD: Response to out of District request/s for aid
9. FCMCD: Request for assistance/aid (resources) from the state of Washington or the United States government to control mosquito activity in the FCMCD during declared arbovirus emergencies.

 SOP PROVISIONS:

1. Adult Mosquito Surveillance/Monitoring:

The Franklin County Mosquito Control District conducts an in-house program of adult mosquito surveillance/monitoring program to monitor mosquito activity and arbovirus detection/presence in Franklin County. The primary function of this program is to ensure timely and effective adult mosquito monitoring through the use of CDC Co2 type baited mosquito traps, mosquito landing rates and customer service calls relating mosquito activity.  Fifteen CDC-Co2 type baited traps are used to collect biting female mosquitoes these traps are deployed in strategic locations throughout Franklin County (see map). We presently deploy these traps every week for a 16-20 hour collection time period during the calendar months of May through early October. In addition to ten traps deployed, additional traps can be deployed when needed in areas of concern for amplified monitoring of mosquito activity and arbovirus detection. In declared arbovirus emergencies the level of adult mosquito surveillance will increase with the placement of more CDC type traps within Franklin County to further aid in virus detection/presence.

2. Adult Mosquito Collection Virology Testing:

The FCMCD has an in-house Taxonomy and Virology testing lab. After each weekly trap deployment the adult mosquito collected in the traps are counted and identified to genus and species. Vector mosquito species are divided into mosquito pools of 25-50 each and are tested for WNV, SLE and WEE virus presence using the MAS-VecTest antigen assay screening. Trap collection reports are sent weekly to the Washington State Department of Health, Office of Environmental Health and Safety. MAS-VecTest assay test results for virus presence or non-presence are also completed in the report and if a positive WNV/SLE/WEEE presence is found it must be sent to the WSU lab in Pullman Washington for confirmation that the assay is positive for virus presence.

3. Mosquito larvae prevention: Eliminating/modifying mosquito breeding habitats:

The FCMCD identifies and initiates activities to reduce the amount of mosquito breeding habitat area when feasible and within regulations. These activities are; draining and/or filling of areas of shallow stagnate water, increase flow rates in irrigation and drainage canals, elimination of water holding waste containers and the reduction and/or elimination of vegetation in slack/stagnant water which support mosquito breeding areas. Most of these activities can be achieved through cooperative agreements with property owners, other agencies, political subdivisions and public education.

4) Mosquito larvae prevention: Abatement of mosquito larvae in there aquatic habitats:

Mosquito larvicide applications are given top priority since this type of control is more selective and effective in reducing mosquito populations. This type of mosquito control measure requires considerable personnel, equipment, materials, planning, mosquito survey work and expense.

4) Mosquito larvae prevention: Control of mosquito larvae in there aquatic habitats (continued):

However, these types of applications offer the best long-term control for mosquitoes.
Bacillus thuringiensis israelensis (Bti), Bacillus sphaericus (Bs) are used for mosquito larvicide’s and applied to mosquito breeding areas when mosquito larvae are found in the 1st to 3rd  instar life stages. Methoprene (IGR) is used for mosquito larvicide and applied to mosquito breeding areas when mosquito larvae are found in the 1st to 4th  instar life stages and Agnique (MMF) is used for mosquito larvicide and pupacide and applied to mosquito breeding areas when mosquito larvae/pupa are found in any life stage .

5) Adult mosquito intervention: Air space spraying of Ultra low volume applications of mosquitocides to control adult mosquito activity:

The use of ultra low volume (ULV) insecticide spray is completed in the FCMCD where mosquito trapping, landing and biting rate counts and verifiable complaints from county residents indicate flying adult mosquito activity. The current mosquito insecticide used in ULV treatments by the District is Malathion ULV concentrate a non-residual insecticide with excellent efficacy against flying mosquitoes. Applications of Malathion are completed to reduce mosquito populations for county resident’s health protection and the reduction of biting mosquito pests.

All ULV treatments are announced publicly at the beginning of the mosquito season (May). The FCMCD has established a “Call Before Spraying List “ for those residents of the FCMCD who wish to be called prior to ULV spraying in the areas in which they live. All ULV treatments are restricted to Franklin County and all treatments are applied according to the insecticide’s label directions. All treatment equipment is calibrated as per the insecticide label directions and is certified yearly as correctly operational.

Exceptions to the above are reviewed on a case-by-case basis with priority given to emergency health related issues. Changes to these operational plans shall be conditionally set on the specific site to be treated, the insecticide to be used and the time frame in which the exception will be in effect. During declared arbovirus emergencies ULV spraying treatments will no-doubt increase throughout the county to ensure the reduction of flying adult mosquito activity.

6) Alerts and declaration of Arbovirus Emergency; From the Washington State Department of Health:

The FCMCD completes weekly antigen assays for the presence of WNV/SLE/WEE so that risks can be determined and responses can be enacted quickly. Public Alerts for Arbovirus are declared by the Washington State Department of Health. These alerts are given through a variety of media sources. The FCMCD will respond to the arbovirus alert issued by the Health Departments/Agencies as outlined in the FCMCD Operational Plan and in the protection provisions of this Arbovirus Emergency SOP.

7) FCMCD Guidelines for the Phased Response to Arbovirus Emergencies

Phased Response Categories – (Definitions and Recommended Response):

0 – Risk Category:
Probability of outbreak in humans – None:

Definition – Off-season: adult vectors inactive, climate unsuitable for breeding.

Recommended Response: Secure surveillance and control resources necessary to enable emergency response. Initiate community outreach and public education programs.

1a – Risk Category:

Probability of outbreak in humans – Remote:

Definition – Spring, summer or fall; areas unlikely to have arbovirus epizootic during the year based on lack of previous or current arbovirus activity in the region.

Recommended Response: Response as in Risk Category 0, plus: Conduct entomologic survey (inventory and map mosquito populations); community outreach and public education; monitor avian mortality, human encephalitis/meningitis and equine surveillance.

1b – Risk Category:
Probability of outbreak in humans – Remote:

Definition – Spring, summer or fall; areas anticipating arbovirus epizootic during the year based on previous or current arbovirus activity in the region; no current surveillance findings indicating arbovirus epizootic activity in the area.

Recommended Response: Response as in Risk Category 1a, plus: Source reduction; use larvicides at specific sources identified by entomologic survey and targeted at likely amplifying and vector species; maintain avian mortality, vector and virus surveillance; public education emphasizing source reduction.

Phased Response Categories – (Definitions and Recommended Response):

2 – Risk Category:
Probability of outbreak in humans – Low:

Definition – spring, summer or fall; areas with initial, sporadic, or limited arbovirus activity in birds and/or mosquitoes.

Recommended Response: Response as in Risk Category 1b, plus: increase larval control and source reduction and public education emphasizing personal protection measures, particularly among the elderly. Enhance human surveillance activities to further quantify epizootic activity such as mosquito trapping and testing. Target and monitor (efficacy) adult mosquito control when surveillance indicates likely potential for human risk to increase.

3 – Risk Category:
Probability of outbreak in humans – Moderate:

Definition – spring, summer or fall; areas with initial confirmation of arbovirus in a human and/or horse, or moderate arbovirus activity in birds and/or mosquitoes.

Recommended Response: Response as in Risk Category 2, plus: Increasing adult mosquito control and monitoring (efficacy) as surveillance indicates likely potential for human risk or persist or increase.

4- Risk Category:
Probability of outbreak in humans – High:

Definition – Spring, summer or fall; quantitative measures indicating arbovirus epizootic activity at a level suggesting high risk of human infection (for example high dead bird densities, high mosquito infection rates, multiple positive species, horse or mammal cases indicating escalating epizootic transmission, or human case and high levels of epizootic activity) and abundant adult vectors.

Recommended Response: Response as in Risk Category 3, plus: Expand public information program to include TV, radio and newspaper (use repellent, personal protection, continued source reduction, risk communication about adult mosquito control; initiate or continue active surveillance for human cases; Continue escalating adult mosquito control and monitoring (efficacy) in target areas of potential human risk.

5- Risk Category:
Probability of outbreak in humans – Outbreak in progress:

Definition – Multiple confirmed cases in humans; conditions favoring continued transmission to humans.

Recommended Response: Response as in Risk Category 4, plus: Enhanced risk communication about adult mosquito control. Escalated adult mosquito control and monitoring (efficacy) in target areas of human risk. If outbreak is widespread and covers multiple jurisdictions, request resources aid (county, state, federal) for widespread aerial spraying for adult mosquito control.

8) FCMCD: Response to out of District request for aid:

The FCMCD Board of Trustees wants to cooperate with other government agencies in the time of Arbovirus emergencies. However, the resources of the FCMCD are very limited. The Board of Trustees of the FCMCD can consider requests for aid from other government agencies when accompanied by a funding source and liability protection for mosquito control outside of the FCMCD, but the public health protection of the District’s population is its primary duty and first priority.

9) FCMCD: Request for assistance/aid (resources) from the state of
Washington or the United States government to control mosquito activity in
the FCMCD during declared arbovirus emergencies. 

In the advent that the FCMCD is not able to fulfill its primary duty for public health protection from arbovirus emergencies of its population,. The FCMCD will request aid from other mosquito control districts, the state of Washington and/or the United States government e.g. FEMA, United States Military, etc.