Health & Medical Resources Guide
Herald Journal Health & Medical Resources Guide
published July 2011
Minnesotans can take steps to protect themselves from tick-borne illnesses
By Ivan Raconteur, Herald Journal Editor
They are small, tenacious, and abundant. Scientists call them ixodes scapuluaris, or black-legged ticks. Most people know them as deer ticks or bear ticks.
These terms all refer to the same kind of ticks, and whatever we call them, they can be vectors (carriers) of some nasty diseases.
Deer ticks are much smaller than wood (or dog) ticks.
Recently, the Minnesota Department of Health (MDH) issued some warnings about black-legged ticks in Minnesota.
On June 29, the MDH announced that Minnesota had recorded its first death from tick-borne powassan (POW) virus, a tick-borne flavivirus related to West Nile virus that can cause encephalitis or meningitis.
A second case of encephalitis likely due to POW virus was also reported.
The press release emphasized the use of repellents containing DEET or permethrin to prevent tick bites.
Six POW cases were identified in Minnesota residents from 2008-2010. In 2011, two cases of encephalitis likely due to POW virus have been identified to-date.
One case, a woman in her 60s from northern Minnesota, died from the infection. The other case, a man in his 60s from Anoka County, is recovering at home.
In a release directed toward medical professionals, the MDH noted:
• One strain of POW virus is transmitted by black-legged ticks, which also carry Lyme disease, anaplasmosis, and babesiosis.
• POW cases in Minnesota from 2008-2011 were from exposure to ticks in a wide area of northern Minnesota. MDH has also identified POW-positive ticks across northern Minnesota and in southeastern Minnesota.
• Medical providers should consider the possibility of POW virus infection in patients with central nervous system disease who have recent histories of activities in wooded areas (with or without known tick bites) during Minnesota’s warm weather months.
• The only laboratories that offer testing for POW virus are at state health departments (including MDH) and CDC. At this time, no commercial laboratories offer serologic testing for the virus.
In March, the MDH announced that tick-transmitted disease season had arrived. Warm weather brings out the ticks.
The ticks become active when temperatures climb above freezing. While much larger numbers of ticks are found during the peak of the tick-transmitted disease season, from May through early July, it is also important for people to protect themselves from the ticks if they spend time in wooded or brushy habitat, even outside of the peak period.
A variety of diseases may be spread by ticks in Minnesota. The majority of tick-transmitted diseases result from the bite of an infected black-legged tick.
According to the MDH, most tick bites do not result in disease, but it is a good idea to recognize and watch for the early symptoms of the more commonly encountered tick-transmitted diseases in Minnesota.
In May. the MDH announced that anaplasmosis rivals Lyme disease in terms of reported cases, and record numbers of Minnesotans became sick from tick-borne diseases in 2010, including:
•. Rocky Mountain spotted fever (RMSF).
Although RMSF is considered rare in Minnesota, MDH receives a few reports every year in patients with no travel history. A Dakota County child who contracted the infection in Minnesota died of RMSF in 2009.
RMSF is carried by dermacentor ticks, which are common in wooded or brushy areas throughout the state.
Signs of RMSF can include fever, maculopapular or petechial rash, and thrombocytopenia.
• Lyme disease is an illness that may affect the skin, joints, nervous system, heart, and other areas of the body. People of all ages can get Lyme disease, which is caused by the bacteria, Borrelia burgdorferi. The bacteria are transmitted to humans by the bite of an infected black- legged tick.
According to information provided by the MDH, recognizing the early signs and symptoms of Lyme disease is important.
If you have one or more of these signs and symptoms within three to 30 days after a deer tick bite or spending time in wooded areas where deer ticks are present, see your physician immediately.
• A characteristic skin rash, called erythema migrans, has a “bull’s eye” appearance a red ring with a central clearing. Not everyone recognizes or gets the rash, and not all rashes have central clearing.
• Fever and chills
• Muscle and joint pain
The rash begins as a small, raised red area that may expand to several inches in diameter. It may appear on one or more places on the body and is usually not painful or itchy.
If a person is not treated early in the disease, these late signs and symptoms may develop weeks, months, or years after the tick bite:
• multiple rashes
• facial paralysis on one side
• weakness, numbness, or pain in arms and legs
• irregular heartbeat
• memory, concentration problems
• chronic arthritis in one or more joints, usually the knees, which may be swollen and painful
The diagnosis of Lyme disease is based on signs and symptoms, presence of the characteristic rash, and a history of exposure to deer ticks. A blood test may be helpful in confirming the diagnosis.
Antibiotics are used to treat Lyme disease.
Lyme disease is easiest to treat when diagnosed during the early stages.
Other tick-borne diseases
Two diseases which appear to be less common than Lyme disease human anaplasmosis and babesiosis can also be transmitted by the deer tick.
The signs and symptoms of human anaplasmosis and babesiosis are sudden and severe and can include:
• High fever.
• Muscle aches.
• Chills and shaking.
• Severe headache.
Less frequent symptoms of anaplasmosis include nausea, vomiting, cough, and aching joints. Anaplasmosis and babesiosis can be treated with antibiotics and other medications by your physician.
The deer tick
Deer ticks search for a host at ground level. Ticks acquire the disease agents from the white-footed mouse and other small mammals.
A deer tick starts as a six-legged larva, which does not transmit disease.
Most cases of tick-borne disease are caused by the nymph, which looks like a freckle or speck of dirt. The nymph feeds from May through July.
The larger adult ticks feed in fall and early spring, and are easier to see and remove. After feeding on deer, the female lays her eggs, which hatch into larvae in May and June.
Only the nymphs and adult female can transmit disease. The adult female has a reddish-orange back.
Wood ticks (also called dog ticks)
Larger than deer ticks, wood ticks have white markings on their back and do not transmit Lyme disease, human anaplasmosis, or babesiosis.
How to protect yourself from ticks
• When in the woods, wear a repellent with DEET or permethrin to avoid picking up ticks. Follow directions on the label.
• Create a barrier to ticks by tucking pants into socks or boots.
• Wear light-colored clothes so ticks are visible.
• Check and recheck for ticks.
• These precautions are most important during May-June and the fall.
• Use tweezers to grasp the tick close to its mouth.
• Gently and slowly pull the tick outward.
• Apply an antiseptic to the bite.
• Do not burn it off or use petroleum jelly.
Not all people bitten by a deer tick will get a disease. Not all deer ticks carry diseases. If a deer tick is infected, it must be attached for at least 24 hours before it can transmit Lyme disease.
Prompt removal of attached ticks prevents disease.