Anaplasmosis

Anaplasmosis is a disease caused by a rickettsial parasite of ruminants, "Anaplasma" spp. The organism occurs in the erythrocytes and is transmitted by natural means through by a number of haematophagous species of ticks and flies. It can also be transmitted iatrogenically by the use of surgical, dehorning, castration, and tattoo instruments and hypodermic needles that are not disinfected between uses.

The organism can go through a complete lifecycle in the gut of certain species of ticks but the flies appear to be only a mechanical vector, thus, not as important in the maintaining the disease in any given area. The disease causes severe anemia and wasting in adult cattle which are infected. Young cattle and most other ruminants will not show clinical signs if infected but may serve as carriers. Since the organism "hides" from the body's immune system in red blood cells, it is difficult if not impossible for an infection to be totally cleared. As the immune response wanes, the organism again builds up and the host relapses.

In the United States, anaplasmosis is notably present in the south and west where the tick hosts "Dermacentor" spp. are found. Although vaccines have been developed, none are currently available in the United States. Early in the 20th century, this disease was considered one of major economic consequence in the western United States. In the 1980s and 1990s, control of ticks through new acaricides and practical treatment with prolonged-action antibiotics, notably tetracycline, has led to the point where the disease is no longer considered a major problem.

Cases of coinfection with tick-born microorganisms are being increasingly reported in the last decade [Paul D. Mitchell,* Kurt D. Reed, and Jeanie M. Hofkes “Immunoserologic Evidence of Coinfection with Borrelia burgdorferi, Babesia microti, and Human Granulocytic Ehrlichia Species in Residents of Wisconsin and Minnesota” // Journal Of Clinical Microbiology, Mar. 1996, p. 724–727.] [Micha Loebermann, Volker Fingerle, Matthias Lademann, Carlos Fritzsche, Emil C. Reisinger “Borrelia burgdorferi and Anaplasma phagocytophilum Coinfection” // Emerging Infectious Diseases, Feb, 2006.] [Walid MS, Ajjan M, Patel N: Borreliosis And Human Granulocytic Anaplasmosis Coinfection With Positive Rheumatoid Factor And Monospot Test: Case-Report. The Internet Journal of Infectious Diseases. 2007; Volume 6, Number 1.] , perhaps explaining the variable manifestations and clinical responses noted in some patients with tick-transmitted diseases. In such clinical settings, laboratory testing for coinfection is indicated to ensure that appropriate antimicrobial treatment is given.

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