Anaplasmosis
Anaplasmosis is an infectious disease caused by the bacterium Anaplasma phagocytophilum, which is transmitted through the bite of infected ticks. In North America, the primary vectors are black-legged ticks (Ixodes scapularis) and Pacific black-legged ticks (Ixodes pacificus), while in Europe and Asia, other species like Ixodes ricinus and Ixodes persulcatus are involved. People who spend time in tick-infested areas are at risk, especially those who are immunocompromised, as they may experience more severe complications if the infection is not treated promptly. Symptoms typically manifest within three weeks of exposure and can include fever, headache, chills, muscle aches, vomiting, and malaise, making diagnosis challenging. Confirmation of the infection is possible through blood tests that detect the bacterium or antibodies. Treatment usually involves a course of tetracycline antibiotics, commonly doxycycline, for 10 to 14 days. Preventive measures include avoiding tick habitats, using repellents, wearing light-colored clothing to spot ticks easily, and checking for ticks on the body after potential exposure. Understanding these aspects of anaplasmosis is crucial for awareness and timely intervention.
Anaplasmosis
Anatomy or system affected: All
Also known as: Human granulocytic anaplasmosis, human granulocytic ehrlichiosis
Definition
Anaplasmosis is an infection caused by the bite of a tick infected with the bacterium Anaplasma phagocytophilum .
Causes
A. phagocytophilum is transmitted by black-legged ticks (Ixodes (tick) scapularis) and Pacific black-legged ticks (I. pacificus) in North America, by the common tick (I. ricinus) in Europe, and by the Taiga tick (I. persulcatus) in Asia. Common reservoirs for ixodid ticks include deer and the white-footed mouse (Peromyscus leucopus) and other small mammals.
Risk Factors
People who frequent tick-infested environments are at risk of being bitten by an infected tick and of contracting anaplasmosis. Immunocompromised persons are at greater risk of complications if not treated promptly.
Symptoms
The symptoms of anaplasmosis typically occur within three weeks of exposure to a tick bite and include fever, headache, chills, muscle aches, vomiting, and malaise. The nonspecific nature of symptoms can make it difficult to diagnose anaplasmosis, but expedient treatment is important to reduce the chance of complications from the disease, particularly in immunocompromised persons.
Screening and Diagnosis
Anaplasmosis may be suspected based on a person’s symptoms and a history of recent tick exposure. Infection can be confirmed by identifying the bacterium in blood samples by polymerase chain reaction and by testing blood serum for antibodies by indirect fluorescent antibody assay. Blood samples may also indicate infection by the characteristic clustering of bacteria in infected cells.
Treatment and Therapy
Tetracycline antibiotics, particularly doxycycline, are prescribed for the treatment of anaplasmosis. Ten to fourteen days is the typical course of treatment.
Prevention and Outcomes
The best way to prevent anaplasmosis is to avoid habitats where ticks are likely to be found; these habitats include wooded areas and tall grasses. Because avoidance of these habitats is not always possible or preferable, one can take measures to limit exposure to ticks, such as by wearing light-colored clothing to increase the visibility of ticks, by applying repellents containing permethrin or NN-diethyl metatoluamide (DEET), and by thoroughly checking one’s body for ticks, particularly around the hairline.
Bibliography
Bakken, J. S., and J. S. Dumler. “Clinical Diagnosis and Treatment of Human Granulocytotropic Anaplasmosis.” Annals of the New York Academy of Sciences 1078 (October, 2006): 236-247.
Bratton, R. L., and G. R. Corey. “Tick-Borne Disease.” American Family Physician 71 (2005): 2323.
Chapman, Alice S., et al. “Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever, Ehrlichioses, and Anaplasmosis—United States.” Morbidity and Mortality Weekly Report 55, RR-4 (March 31, 2006).
Demma, Linda J., et al. “Epidemiology of Human Ehrlichiosis and Anaplasmosis in the United States, 2001-2002.” American Journal of Tropical Medicine and Hygiene 73, no. 2 (2005): 400-409.
Wormser, Gary P. “The Clinical Assessment, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: Clinical Practice Guidelines by the Infectious Diseases Society of America.” IDSA Guidelines, November 1, 2006, p. 43.