Mosquito & Tick-borne Disease Program

Franklin County’s Mosquito and Tick-borne Disease program works hard to mitigate the risk of mosquito and tick-borne diseases in our community through surveillance, control, and education.

 

In 2001, the Pennsylvania Department of Environmental Protection (DEP) began its mosquito surveillance program due to the prevalence of West Nile Virus found in the state. From the very beginning, the program has worked to mitigate the risk of West Nile Virus, as well as other mosquito-borne diseases through surveillance, control, and education. Beginning in 2018, the Pennsylvania Department of Environmental Protection also began a tick surveillance program to understand tick-borne disease prevalence, habitat, and species distribution. Every year Franklin County submits a grant application to DEP to cover the cost of completing mosquito and tick work in the county. Jason Goetz is the county’s full time Mosquito and Tick-borne Disease Specialist.

Mosquito Surveillance

Mosquitoes are monitored at larval and adult stages. Larval surveillance begins in late March or early April and focuses on the habitat within the county that breeds early spring emergers. These habitats include flood water areas, wetlands, and woodland pools. As the spring turns into summer, larval surveillance expands to different habitat for different species. Retention ponds and artificial containers are two of the biggest larval problem sources. How much larval surveillance conducted largely depends on the amount of precipitation received. A good rule of thumb is more precipitation equates to more abundant breeding habitat, and therefore more surveillance is conducted.

Adult surveillance begins in early May. Adult surveillance is conducted by use of host-seeking and gravid traps in strategic areas where there is a population of people, mosquito breeding habitat, and mosquito resting habitat. While the program surveys for many different species of mosquitoes in Franklin County, the three main target species are Culex pipiens (Common House mosquito), Culex Restuans (White Dotted mosquito), and Ades albopitus (Asian Tiger mosquito). The Common House and White Dotted mosquito are the ones most likely to carry and transmit West Nile Virus. Specifically trapping these mosquitoes helps to determine the prevalence of West Nile Virus. The invasive Asian Tiger mosquito is the county’s biggest nuisance mosquito, as it is a relentless day-time bitter. The program surveys this mosquito to understand their spread across the county and to identify and control problem areas.

Larval and adult surveillance usually end in October when night-time temperatures get too low for mosquitoes to breed.

mosquito trapMosquito Trap

 

Mosquito Control

Control efforts focus on both large and small scale areas of concern in communal areas. Although we can offer assistance through education on how to eliminate breeding habitat, this program is not for private extermination for individual homes. Instead, employees seek out mosquito habitat that has the potential to develop into large scale mosquito problems and work to eliminate the larval source before it becomes an issue.

The program’s biggest focus is on retention ponds in communal areas where thousands of mosquitoes can emerge. Control efforts are implemented using integrated pest management (IPM), which considers several different types of control. Each area of breeding habitat is evaluated for the best possible control type, and this does not always mean pesticides are used. Oftentimes larval sources can be mechanically controlled by methods such as turning wheelbarrows over and changing out the water in bird baths every few days. Environmental factors are considered to take care of mosquito issues as well. For example, it typically takes 8-18 days for mosquitoes to transform from egg to adult. Often, day old larvae are found in shallow water in a retention pond. If the forecast is calling for high heat with no precipitation, the water will evaporate, killing the larvae before they become adults.

In other cases where employees cannot rely on environmental factors, a granular larvicide is used. The most common larvicide the program uses contains the active ingredient of Bacillus thuringiensis israelensi (BTI) which is a naturally occurring bacterium found in soil. The product works when the BTI becomes active upon water contact and attaches to decaying matter, which the mosquito larvae eat. Once ingested, the bacterium kills the mosquito larvae. BTI is a great method of control because it does not harm non-target species.

If mosquitoes are breeding and emerging faster than the larval source can be controlled, there will be issues with adult mosquitoes. Adult controls are determined based on species caught, trap numbers, and the prevalence of West Nile Virus present in localized areas. The first option to control adult mosquitoes is a barrier spray. Barrier sprays are most effective for high mosquito populations that are localized to about a 1 to 2 acre area. Using backpack sprayers, the product is sprayed onto dense, non-flowering vegetation which the adult mosquitoes rest on during the day. The adult mosquitos are killed on contact. This spray can have a residual effect and can continue to be effective for up to four weeks. The second option is a truck mounted spray which is justified by the vector index (VI). The VI is calculated using a mathematical equation taking into account the number of mosquitoes trapped and how many of those mosquitoes tested positive for West Nile Virus in a one-mile radius. If the VI is over 300, a truck mounted spray may be required in an effort to mitigate both the disease and mosquito prevalence. This spray is conducted at dusk when mosquitoes are most active and non-target species such as bees are not. The product is broadcasted as a very fine mist behind the truck. It will hover in the air for about 15 minutes, dispatching any mosquitoes that come in contact with it. After 15 minutes the product dissipates into tiny microscopic particles and evaporates. Truck mounted sprays are publicly notified events.  

mosquito foggerUsing a Mosquito Fogger to Reduce Adult Mosquito Population

Education and Community Mosquito Control Efforts

It is hoped that the residents of Franklin County will make informed decisions around their property to reduce mosquito breeding habitat. To help with that, every year the program updates and educates the community through events, news articles, and one-on-one visits. Community outreach plays a vital part in mosquito mitigation efforts. Many mosquito species can be kept at bay, especially the Asian Tiger Mosquito, if citizens do their part by removing any artificial container containing water around their property. This includes but is not limited to buckets, old tires, clogged rain gutters, bird baths, unkempt swimming pools; anything that can hold water. Program employees always enjoy hearing from the citizens of Franklin County. Often a citizen phone call about mosquito issues leads to new discoveries of breeding habitat. Once this breeding habitat is found, it is then put on the program’s radar and checked regularly so the mosquito problem does not come back. Only by communication and working together can mosquito issues be mitigated.  

Tick Surveillance

The tick surveillance program began in 2018 and is designed to better understand disease prevalence, habitat, and species distribution. The main focus of the program is the Black-legged tick (Ixodes scapularis), which can transmit Lyme disease along with other pathogens to people. Spring and summer surveillance is conducted for nymphal Black-legged ticks as well as other species of ticks including the American Dog tick (Dermacentor variabilis) and Lone Star tick (Amblyomma americanum).

In the fall surveillance is conducted for the adult Black-legged tick. Black-legged ticks are tested for various bacteria and virus pathogens including Borrelia burgdorferi (Lyme Disease), Borrelia miyamoti (tick-borne relapsing fever), Anaplasma phagocytophilum (Anaplasmosis), Babesia microti (Babesiosis), and Deer Tick Virus (Powassan lineage II).

Lyme Disease is the most prevalent disease that humans contract from a tick bite, and from current testing at the DEP lab, it was determined that 50% of Black-legged tick adults and 25% of Black-legged tick nymphs in Franklin County carry the Borrelia burgdorferi bacteria. All research is conducted on public use lands of Franklin County including parks, Pennsylvania State Game Lands, and State Forests.

Currently six different species of ticks have been collected in Franklin County. These include the American Dog, Black-legged, Lonestar, Winter or Moose (Dermacentor albipictus), Asian Longhorned (Haemaphysalis longicornis), and Gulf Coast Tick (Amblyomma maculatum) (only one Gulf Coast Tick to date).

dragging for ticks with a white cloth in leavesCollecting Ticks through a process called “Dragging”

 

For more information on mosquitos, click HERE.

For more information on ticks, click HERE.