Ehrlichiosis and anaplasmosis are rickettsia-like bacterial infections that are caused by Ehrlichia and Anaplasma bacteria and are spread by infected ticks.
Ehrlichiosis and anaplasmosis are spread through the bites of infected ticks.
Symptoms of ehrlichiosis and anaplasmosis are similar, but anaplasmosis is less likely to cause a rash.
The polymerase chain reaction (PCR) technique, done on a sample of blood, enables doctors to detect the bacteria rapidly.
The antibiotic doxycycline is given as soon as doctors suspect a person has one of these infections.
Avoiding tick bites is the best way to prevent these infections.
Ehrlichia and Anaplasma bacteria can be passed between people and animals and cause infections. Infections that can be passed between people and animals are called zoonotic diseases, or zoonoses (see Introduction to Diseases Spread Between Animals and People (Zoonoses)). See also Ehrlichiosis and Related Infections in Dogs and Anaplasmosis in Horses (Equine Granulocytic Ehrlichiosis).
Ehrlichia and Anaplasma bacteria, like rickettsiae, can live and multiply only inside the cells of a host organism, such as an animal or a person, and cannot survive on their own in the environment. Ehrlichia bacteria inhabit monocytes, and Anaplasma bacteria inhabit granulocytes. Monocytes and granulocytes are types of white blood cells.
Ehrlichiosis is most common in the southeastern and south central United States. Anaplasmosis occurs in the Northeast, mid-Atlantic, upper Midwest, and West Coast of the United States. Anaplasmosis mostly occurs in the United States, but it has occurred in all continents, including Antarctica.
Both infections are spread (transmitted) to people through infected tick bites. Thus, these infections are most likely to develop between spring and late fall, when ticks are most active.
These infections are transmitted by different ticks:
Ehrlichiosis: The lone star tick (Amblyomma americanum)
Anaplasmosis: The blacklegged tick (Ixodes species)
The lone star tick is so named because the adult female is distinguished by a white dot or “lone star” on its back.
This tick transmits the bacteria that cause ehrlichiosis and a bacterium that causes tularemia.
It also transmits the sugar alpha-gal in its saliva, which may cause some people to develop a rare form of allergy to red meat called alpha-gal syndrome.
CDC/ Lauren Bishop
The bacteria that cause Lyme disease and babesiosis are also transmitted by Ixodes blacklegged (deer) ticks and are common in the same areas. Consequently, people have the potential to get more than one infection if they are bitten by a tick infected with more than one type of bacteria.
Because Anaplasma bacteria infect white blood cells, which circulate in the bloodstream, these bacteria may be transmitted through blood transfusions. A few people have developed anaplasmosis after they received a blood transfusion from a person who had been recently infected or who was infected but had no symptoms.
Both infections are more severe in and are more likely to be fatal in people who have a weakened immune system resulting from a disorder (such as HIV infection) or from medications that impair the immune system (such as chemotherapy for cancer or steroids [sometimes called glucocorticoids or corticosteroids]).
Symptoms of Ehrlichiosis and Anaplasmosis
Symptoms of ehrlichiosis and anaplasmosis are similar. Symptoms usually begin suddenly about 9 days after a tick bite. They include fever, chills, muscle aches, weakness, nausea, vomiting, cough, headache, and a general feeling of illness (malaise). Some people have no symptoms.
A rash may develop on the torso, arms, and legs in some people with ehrlichiosis but is not common among people with anaplasmosis.
Compared with ehrlichiosis, stomach pain, nausea, vomiting, diarrhea, headache, and confusion are rare in anaplasmosis.
Ehrlichiosis and anaplasmosis may cause widespread blood clotting (disseminated intravascular coagulation), failure of several organs, seizures, and coma.
Diagnosis of Ehrlichiosis and Anaplasmosis
Blood tests
Doctors do the polymerase chain reaction (PCR) technique using a sample of blood. The PCR technique increases the amount of the bacteria’s DNA and thus enables doctors to identify the bacteria more rapidly.
Doctors do other blood tests to determine the levels of white blood cells (and the amount of antibodies they produce), platelets, and liver enzymes and abnormal blood clotting. The results of these tests may indicate the person has a blood or liver disorder.
Treatment of Ehrlichiosis and Anaplasmosis
Antibiotics
If people who may have been exposed to infected ticks have typical symptoms, doctors start treatment for ehrlichiosis or anaplasmosis before test results are available. When treatment is started early, most people respond rapidly and well. A delay in treatment may lead to serious complications, including death.
Doctors typically give people of all ages, including children, who have ehrlichiosis or anaplasmosis the antibiotic doxycycline. People who have ehrlichiosis take this antibiotic until they improve and have not had a fever for 24 to 48 hours. After this point, people continue to take doxycycline for 5 to 7 days. People who have anaplasmosis take doxycycline for 10 to 14 days.
Although doxycycline can cause tooth staining in children younger than 8 years old, a short, 5- to 10-day course of doxycycline in children of all ages is recommended by the American Academy of Pediatrics and can be used without causing tooth staining or weakening of tooth enamel.
Some people continue to have headaches and feel weak and generally unwell for weeks after treatment.
Prevention of Ehrlichiosis and Anaplasmosis
To prevent these infections, people should take measures to prevent tick bites. (See also the Centers for Disease Control and Prevention: Preventing Tick Bites.)
Preventing tick access to skin includes:
Staying on paths and trails
Tucking trousers into boots or socks
Wearing long-sleeved shirts
Applying repellents that contain diethyltoluamide (DEET), picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone to skin surfaces
Treating clothing, shoes/boots, and gear with permethrin
Some repellents can be toxic to children, so DEET should not be used in infants under 2 months of age, and repellents that contain more than 10% DEET should not be used in children under 12 years of age. OLE and PMD should not be used in children under 3 years of age. Permethrin on clothing effectively kills ticks. Frequent searches for ticks, particularly in hairy areas and on children, are essential in areas where infections transmitted by ticks are common.
Ticks should be removed as soon as possible. An engorged tick should be removed with care and not crushed between the fingers because crushing the tick may result in disease transmission. The tick’s body should not be grasped or squeezed. Removal is best accomplished by grasping the tick with curved tweezers as close to the skin as possible and pulling it directly out. The tick’s head, which may not come out with the body, should be removed, because it can cause prolonged inflammation. The area where the tick was attached and the hands of the person removing the tick should be disinfected with soap and water, rubbing alcohol, or hand sanitizer. Petroleum jelly, lit matches, and other irritants are not effective ways to remove ticks and should not be used.
Ticks cannot be entirely eliminated from large areas in the environment. However, the number of ticks may be reduced by taking steps to remove or prevent tick habitats and by making the environment less appealing and accessible to the animals that carry ticks. Ticks are often found in wood piles, leaf litter, tall grasses, and brush, so people can reduce the number of ticks in their yard by clearing such debris from around their home, especially outdoor play areas. Regular lawn maintenance, including frequent lawn mowing, is key to keeping ticks out of recreational areas and yards. People should remove any trash or unused furniture from their yard, and move outdoor equipment, toys, and seating away from shaded yard edges and trees. People can also install a 3-foot wide barrier of wood chips or gravel between their lawn and wooded areas.
To discourage tick-carrying rodents (such as rats, mice, and squirrels) from entering the yard, people should stack firewood in dry, elevated areas. To discourage other tick-carrying animals, such as raccoons, deer, and stray dogs, from entering the yard, people can install a fence.
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