What is Anaplasmosis?

Anaplasmosis is an infectious disease caused by the bacteria Anaplasma phagocytophilium. The bacteria infect the person’s white blood cells and circulate in the blood stream.

How do you get Anaplasmosis?

Anaplasmosis is transmitted to humans through the bite of ticks infected with the bacteria Anaplasma phagocytophilium. The black-legged tick and the western black-legged tick are the most common carriers of the bacteria and can also carry the bacteria for Lyme disease and Babesioisis. Most infections are caused by ticks in the nymphal (early) life-stage.

Since the bacteria circulates in the blood, transmission can also occur through blood transfusions, organ transplants, as well as perinatally to an infant prior to birth.

Susceptibility and Resistance

All persons are susceptible, however, more severe cases have been reported in those with a compromised immune system.

Incubation Period

The incubation period for Anaplasmosis is 5-21 days.

What are the Symptoms?

The tick bite is painless and the infected individual may not know that they have been bitten. The symptoms of Anaplasmosis include: fever, headache, muscle aches/pains, tiredness, chills, nausea/abdominal pain, cough and confusion. Most infected individuals do not develop all the symptoms. In many infected individuals, the symptoms are very mild and may be unnoticed. The development of a rash may occur, however, a rash is a rare symptom of Anaplasmosis and may indicate, instead, that the patient has been co-infected with Lyme disease or another disease carried by a tick. The symptoms of Anaplasmosis may be similar to the symptoms of Ehrlichiosis and Rocky Mountain spotted fever.

In severe cases, infected individuals may have difficulty breathing, hemorrhages and renal and/or neurological difficulties. Anaplasmosis may be fatal if proper treatment is not received (fatal in less than 1% of cases).

Preventative Measures

Avoid direct contact with ticks, especially in warm summer months when ticks are most active. Avoid wooded and bushy areas with high grass.  Use insect repellent containing 20 percent or more of DEET. Wear protective clothing to cover exposed skin. After possible exposure in outdoor settings, bathe as soon as possible and carefully check skin over the entire body surface. Remove any ticks immediately, since the risk of transmission of the bacteria from the tick increases the longer the tick is attached.


The patient should seek medical care when they suspect that they have been in contact with a tick or symptoms appear that might be due to Anaplasmosis. Early treatment improves recovery time. Less severe cases will recover well with medication; more severe cases may require intravenous antibiotics and hospital care.

Doxycycline is the recommended antibiotic for the treatment of Anaplasmosis and should be the first treatment for patients of any age. Once the patient’s fever subsides and symptoms are eliminated, the treatment should continue for a minimum of 3 days. Generally, the treatment lasts 1-2 weeks, though mild symptoms may persist for weeks after the treatment has terminated.


Where Does It Commonly Occur?

Anaplasmosis is spread by ticks that carry the Anaplasma phagocytophilium bacteria, therefore, the disease can be found wherever there are infected ticks. Anaplasma phagocytophilium is found worldwide, but not all countries require Anaplasmosis infections to be reported to health authorities. Thus, the global distribution of human infections is not clearly known.

In the USA, where Anaplasmosis is a reportable disease, the states of New York, Connecticut, New Jersey, Rhone Island, Minnesota, Wisconsin and California report the vast majority of the annual cases. Although Anaplasmosis can occur at any time of the year, it is most commonly reported in the summer months in the USA, as this coincides with the nymphal stage of the tick.