Babesiosis
Babesiosis is a malaria-like illness caused by a protozoan parasite (Babesia microti in the U.S.; other members of the Babesia genus in Europe) that invades red blood cells, and is primarily transmitted by the deer tick Ixodes scapularis and possibly other related Ixodid ticks
What is Babesiosis?
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In Europe, reported fatal cases of babesiosis have occurred mostly in patients whose spleens have been removed, rendering them more vulnerable to infection. The offending parasite in these cases have been either B. divergens or B. major, to which humans (with spleens intact) are thought to be naturally resistant. In the U.S., reported fatal cases have occurred in patients both with and without spleens; B. microti may be a more virulent agent to which humans are not naturally resistant. However, while many in the U.S. who are exposed to the parasite do suffer severe symptoms, such cases often are self-limiting and are eventually resolved with treatment; fatalities generally are limited to elderly patients with compromised immune systems.
Approximately 200 cases of babesiosis have been reported in the U.S. since the first human case was recognized on Nantucket Island (off the coast of Massachusetts) in 1968.
Where is Babesiosis Prevalent?
The deer (black-legged) tick in the Northeast and upper Midwest, and the Western black-legged tick on the Pacific coast are the primary carriers.
A majority of reported cases occur during the summer months along the immediate coast and off-shore islands of the Northeast.
Symptoms
The symptoms of babesiosis normally begin about a week after a tick bite with a gradual onset of malaise, anorexia and fatigue. This is followed several days later by high fever, drenching sweats, muscle pain and headaches. As with malaria, these symptoms can continue over a protracted period or can abate, then recur.
Diagnosis
Diagnosis involves examining blood smears and recognizing the characteristic "ring" form taken by the Babesia parasite within the red blood cells of the patient.
Treatment
Recommended treatment is a seven-day course of oral quinine plus clindamycin under the careful supervision of a physician. Fatigue, malaise and a low grade fever may persist for weeks or months after treatment has been completed.
Prevention & Control
Deer ticks prefer to hide in shady, moist ground litter, but can often be found above the ground clinging to tall grass, brush, shrubs and low tree branches. They also inhabit lawns and gardens, especially at the edges of woodlands and around old stone walls. Within the endemic range of B. microti (the parasite that infects the deer tick and causes babesiosis), no natural, vegetated area can be considered completely free of infected ticks.
Deer ticks cannot jump or fly, and will not drop from an above-ground perch onto a passing animal. Potential hosts (which include all wild birds and mammals, domestic animals and humans) acquire ticks only by direct contact with them. Once a tick gains access to human skin it generally climbs upward until it reaches a more protected area, often the back of the knee, groin, navel, armpit, ears, or nape of the neck. It then begins the process of inserting its mouthparts into the skin until it reaches the blood supply.
In tick-infested areas, the best precaution against babesiosis is to avoid contact with soil, leaf litter and vegetation as much as possible. However, if you garden, hike, camp, hunt, work outdoors or otherwise spend time in woods, brushy areas or overgrown fields, you should use the following personal precautions to avoid exposure to ticks:
- Wear light-colored clothing with a tight weave to spot ticks more easily and prevent contact with the skin
- Always wear enclosed shoes
- Wear long pants tucked into socks, long-sleeved shirts tucked into pants (however, be aware that ticks search for exposed skin and may climb to the head and neck area if not intercepted first; spot-check clothes frequently)
- Spray clothes with insect repellent containing either DEET or Permethrin (only DEET can be used on exposed skin, but never in high concentrations; make sure to follow the manufacturer's directions carefully)
- Keep long hair pulled back
- When gardening, pruning shrubs, or otherwise handling soil and vegetation, wear light-colored gloves, spot-checking them for ticks frequently
- Avoid sitting directly on the ground or on open stone walls (which attract small mammals)
- Stay on cleared, well-worn trails whenever possible
- During any outing, spot-check yourself and others frequently for ticks on clothes; if you find one, there may be others - check thoroughly
- Remove clothes after leaving tick-infested areas and, if possible, wash and dry them to eliminate any unseen ticks
- Shower and shampoo
- Check yourself, your children and any outdoor pets from head to toe for ticks each night before going to bed (nymphal deer ticks are the size of poppy seeds; adult deer ticks are the size of sesame seeds).
Any contact with vegetation, whether bushwhacking through dense brush or simply playing in the yard, can result in exposure to ticks, so careful daily self inspection is necessary whenever you engage in outdoor activities and the temperature exceeds 40 degrees F (the temperature above which deer ticks are active). Frequent tick checks should include a systematic, whole-body examination each night before going to bed. Performed consistently, this ritual is perhaps the single most effective current method for prevention of babesiosis.
If you DO find a tick attached to your skin, use the following method to remove it:
- Using a pair of fine-pointed tweezers, grasp the tick by the head or mouthparts right where they enter the skin. DO NOT grasp the tick by the body.
- Without jerking, pull firmly and steadily directly outward. DO NOT twist the tick out or apply petroleum jelly, a hot match, alcohol or any other irritant to the tick in an attempt to get it to back out. These methods can backfire and even increase the chances of the tick transmitting the disease.
- Place the tick in a vial or jar of alcohol to kill it.
Prevention is not limited to personal precautions. Those who enjoy spending time in their yards can reduce the tick population in the vicinity of the home by:
- keeping lawns mowed and edges trimmed
- clearing brush, leaf litter and tall grass around houses and at the edges of gardens and open stone walls
- stacking woodpiles neatly in a dry location and preferably off the ground
- clearing all leaf litter (including the remains of perennials) out of the garden in the fall
- keeping the ground under bird feeders clean so as not to attract small mammals
- having a licensed professional spray the residential environment (only the areas frequented by humans) with an insecticide in late May (to control nymphs) and optionally in September (to control adults)
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