Protect yourself against insect-borne disease

It’s almost impossible for tree care workers to avoid insects, but since bug bites can mean much more than a temporary sting, it is important to keep them at bay. Over 700 million cases of mosquito and tick-transmitted diseases are reported each year. The Center for Disease Control (CDC) says that Lyme disease, West Nile virus, enceph-alitis and Rocky Mountain spotted fever are among those illnesses.

The choices for personal protection are growing, thanks to the Agricultural Research Service (ARS) and university scientists. The ARS developed DEET for the military in the 1940s and released it to the public in the ’50s. Although it is still the most effective and widely used repellant, recent research may result in products that will outperform the synthetic chemical formulation.

The ARS received a patent in May for a method of producing a natural repellant from pine oil. Tests show that it is equally effective as DEET against ticks and better at warding off mosquitoes. Inexpensive to create, the pine oil preparation is also sustainable  and better for the environment. Those who are concerned about the safety of DEET will welcome any commercial products derived from these findings.

ARS and University of Florida scientists are studying several promising N-acylpiperidine mosquito repellent candidates. Some of the preparations provide protection for three times longer than DEET. Safety testing has not been completed, and any product development is some time away.

Dealing with mosquitoes

In recent years, West Nile virus has received the most coverage among mosquito-borne diseases. The pests also carry other arboviral encephalitis viruses such as St. Louis encephalitis, western equine encephalitis, Venezuelan equine encephalitis, eastern equine encephalitis, La Crosse virus and other California serogroup viruses. Dengue fever, malaria, Rift Valley fever and yellow fever threaten those outside the United States. Infection with any of these diseases is rare; healthy, active people are less likely to be affected. A West Nile vaccine is currently under development.

Why do some people get more mosquito bites than others? Chemicals, color and body heat seem to be factors. Folic acid is a chemical that appears to be quite attractive, and fragrances from hair spray, perfumes, deodorants and soaps can cover chemical cues, to either attract or repel the mosquito. Dark colors capture heat and make most people more desirable to mosquitoes, while light colors refract heat and are generally less attractive. Detergents, fabric softeners, perfumes and body odor can counteract the effects of color.

Wearing light-colored, long-sleeved shirts and long pants is one way to avoid bites. The CDC recommends using repellants containing DEET, picaridin, oil of lemon eucalyptus, PMD (synthesized version of oil of lemon eucalyptus), or IR3535.

A relatively new option is permethrin-treated clothing. The permethrin is odorless and lasts at least 25 washings. One manufacturer says that its protection extends for the entire life of the apparel, stated to be 70 launderings. Some brands also incorporate sunscreen into clothing, including shirts, pants and hats. In addition to mosquitoes, the clothing defends against ticks, no-see-ums (midges), ants, flies and chiggers.

Photo courtesy of SherrillTree.
A large beehive will ruin any tree care worker’s day.

Guarding against ticks

Ned Patchett, a consulting arborist who inventories and assesses trees on undeveloped properties in the San Francisco Bay area, says ticks are one of his biggest problems.

“In an hour you can get 20 ticks on you,” he says. Most tick bites are painless.

Painful or not, tick bites are well-known for resulting in disease. Ehrlichiosis, Lyme disease, Rocky Mountain spotted fever, southern tick-associated rash illness (STARI), tick-borne relapsing fever and tick typhus are among the disorders for which ticks are blamed. Most are treatable when diagnosed promptly.

Lyme disease infections have become the most common. Tony Tresselt of Arborist Enterprises, Inc. in Pennsylvania attributes that to increased host animals, such as deer and mice, and to improved diagnostic techniques. A vaccine was developed a few years ago, but poor sales prompted its manufacturer to discontinue production.

Many of the defenses used against mosquitoes are also effective for ticks. Light-colored clothing aids in spotting ticks. The ARS recommends tucking pants into socks and sealing the meeting point with wide tape. Taping shoelaces prevents entry through the eyelets. Use hats and hair ties to prevent ticks from jumping from clothing onto the head or body.

After working in a tick-prone area, clothing should be placed in a closed plastic bag until it can be washed in warm or hot water; ticks can survive cool water. Workers should inspect themselves and remove any ticks uncovered. One important reason is that the type of tick that carries Lyme disease is so tiny, it’s almost impossible to see without close examination. However, it must remain attached to the body for 24 to 36 hours to transmit the bacteria.

Ticks are often found in leaf litter in or near woods, and may gather around stone fences and fallen logs. Clearing a work area of these items, when possible, helps avoid encounters with these insects.

More pests to fight

Each part of the country has its own unique insect populations that cause grief for tree care crews. In Seattle, Out On A Limb Tree Company Owner Kathy Holzer says the worst enemy is the bald-faced hornet. The highly aggressive pests are most common from May until October.

Holzer says it’s difficult to detect the well-hidden nests in advance, so workers must carry spray for quick extermination. When she is able to identify a nest, work stops until it can be destroyed.

Other stinging insects, such as bees, wasps and yellow jackets, can also be dangerous, especially to those who are allergic. Those with known allergies should carry medication, and anyone who is stung should be watched. Difficulty breathing may signal an allergic reaction such as anaphylactic shock. If that occurs, or someone sustains multiple stings, medical aid should be sought immediately.

The author is a freelance writer based in Greensboro, N.C.

Symptoms of Select Insect-Borne Diseases

Photo by Scott Bauer, ARS.
Currently the most used repellent ingredient, DEET may be replaced by newer formulas developed by the Agricultural Research Service and university scientists.

Lyme Disease
Local Lyme disease that does not spread beyond the site of the bite may have symptoms of flu-like feelings, including headache, stiff neck, fever, muscle aches and fatigue. About 60 percent of light-skinned patients notice a unique enlarging rash days or weeks after the bite. On dark-skinned people, this rash resembles a bruise.

Disseminated Lyme disease has spread to other organs. Symptoms may include fatigue, severe headache, fever and severe muscle aches or pain. Many organs, including the brain, eyes, liver and lungs, can be affected.

West Nile Virus
A person infected with West Nile virus may have no symptoms or the infection can develop into West Nile fever or severe West Nile disease. Symptoms of West Nile fever may include fever, headache, fatigue and body aches. Severe disease may be signaled by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

Rocky Mountain Spotted Fever
Early symptoms of Rocky Mountain spotted fever include fever, nausea, vomiting, severe headache, muscle pain and lack of appetite. A pink rash appears within two to five days. Abdominal pain, joint pain and diarrhea may develop as the fever progresses.

Eastern Equine Encephalitis
Most people have no symptoms; others have only a mild flu-like illness with fever, headache and sore throat. For people with infection of the central nervous system, a sudden fever and severe headache can be followed quickly by seizures and coma. About half of those who develop the central nervous system infection do not survive.