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Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum and is transmitted by the bite of an infected tick, particularly the blacklegged tick (Ixodes scapularis) and the western blacklegged tick (Ixodes pacificus). The disease is characterized by fever, headache, chills, and muscle aches. Anaplasmosis is diagnosed based on clinical signs and symptoms and then later confirmed using laboratory tests. The most effective treatment is doxycycline. Tick-bite prevention is the best way to avoid being infected.
Anyone living or recreating where the blacklegged tick may be present could become infected. Since the disease became reportable in the U.S. (1999), the number of anaplasmosis cases reported has increased steadily. Anaplasmosis is most frequently reported from the upper Midwestern and Northeastern U.S. The geographic distribution of anaplasmosis corresponds with that of Lyme disease as both diseases are transmitted by the same kind of tick.
Approximately 90% of all reported cases to the CDC originated from New York, Connecticut, New Jersey, Rhode Island, Minnesota, and Wisconsin. The frequency of reported cases is highest among males and individuals over 40 years of age with a peak in cases occurring in June and July.
If you find a tick attached to you and are concerned that it may be a blacklegged tick, the Michigan Department of Health and Human Services provides a free "Tick Identification Kit." Contact your local health department for information about obtaining a submission kit. If a kit is not available, see additional information regarding the tick submission process.
What are the signs and symptoms of anaplasmosis?
The bacterium that causes anaplasmoses infects white blood cells. Those individuals infected with anaplasmosis typically develop signs and symptoms approximately 1-2 weeks after the bite of an infected tick. Symptoms may include fever, headache, muscle pain, nausea, chills, and/or general discomfort. A rash however, is rare with this disease. Severe symptoms include difficulty breathing, kidney failure, and/or neurological problems. In rare cases, anaplasmosis can be fatal if not treated properly.
How is anaplasmosis diagnosed?
Anaplasmosis is a difficult disease to diagnose because the symptoms are often non-specific. Diagnostic tests, especially those based on the detection of antibodies, may appear negative for the first 7-10 days of illness.
For this reason, healthcare providers must use their judgment to treat patients and may find important information in the patient’s history and physical examination that may aid in diagnosis. Information such as recent tick bites, exposure to areas where ticks are likely to be found, or history of recent travel to areas where anaplasmosis is commonly found can be helpful. The healthcare provider may also look at routine blood tests, such as a complete blood cell count or a chemistry panel. Clues such as a low platelet count (thrombocytopenia), low white blood cell count (leukopenia), or elevated liver enzyme levels are helpful predictors of anaplasmosis, but may not be present in all patients. After a suspect diagnosis is made on clinical suspicion and treatment has begun, additional laboratory testing may be used to confirm the diagnosis.
Treatment is most effective if started early in the course of the disease.
Additional information regarding the diagnosis of anaplasmosis can be found on the CDC website:
A Practical Guide for Physicians and Other Health-Care and Public Health Professionals
What should I do if I have a tick that I want to identify or test?
Knowing what kind of tick bit you may be important in knowing what your risk of disease is. The Michigan Department of Health and Human Services (MDHHS) provides tick identification at no charge to Michigan citizens. Ticks that are submitted from people that are identified as blacklegged ticks (also known as deer tick) and are alive will be forwarded to the MDHHS Bureau of Laboratories for Lyme disease screening only at no cost. Ticks that are dead when they are received or are from animals (dog, cat, horse, etc.) will not be tested however, they will be identified to species and lifestage.
See more information regarding the tick identification and testing program, in addition to instructions on how to ship the tick, on Tick Identification and Testing in Michigan.
Tickborne Diseases In Michigan is a quick reference table for health care providers that includes vector species, incubation period, signs and symptoms, general laboratory findings, laboratory diagnosis, and treatment for the following tickborne diseases: Lyme disease, anaplasmosis, babesiosis, and Rocky Mountain spotted fever.
What is the treatment for anaplasmosis?
Doxycycline is the first line treatment for adults and children of all ages and should be initiated immediately whenever anaplasmosis is suspected. Infected individuals who are treated early and correctly may recover quickly via outpatient medication. However, those experiencing more severe symptoms may require hospitalization. Treatment should never be delayed pending the receipt of laboratory results, or be withheld on the basis of an initial negative laboratory result.
- The Tick Management Handbook
An integrated guide for homeowners, pest control operators, and public health officials for the prevention of tick-associated disease (Connecticut Agricultural Experiment Station)
- CDC: Guidance for Clinicians: Recommendations for Patients After a Tick Bite
- CDC: What To Do After a Tick Bite
- The Clinical Assessment, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: Clinical Practice Guidelines by the Infectious Diseases Society of America
- Michigan's Five Most Common Ticks
Ticks are significant vectors (carriers) of pathogens that cause human and animal disease. In Michigan, tick-borne diseases are rare, but they do occur and can be serious if not properly diagnosed and treated.
- Michigan Tick ID Card
Pocket-sized card for identifying common ticks in Michigan. Information regarding tick removal and tick-bite prevention.
- CDC: Anaplasmosis
- Tickborne Diseases of the U.S. - information from the CDC
- Ticks and Your Health
Brochure describing Lyme disease and other tick-borne diseases in Michigan. Other topics covered include tick-bite prevention, preventing ticks on pets, and landscape techniques to minimize tick risk.
- Tick Removal