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Human monocytic ehrlichiosis
Ehrlichia chaffeensis
Specialty	Infectious diseases

Human monocytotropic ehrlichiosis is a form of ehrlichiosis associated with Ehrlichia chaffeensis. This bacterium is an obligate intracellular pathogen affecting monocytes and macrophages.

Symptom and signs

The most common symptoms are fever, headache, malaise, and muscle aches (myalgia). Compared to human granulocytic anaplasmosis, rash is more common. Laboratory abnormalities include thrombocytopenia, leukopenia, and elevated liver tests.

The severity of the illness can range from minor or asymptomatic to life-threatening. CNS involvement may occur. A serious septic or toxic shock-like picture can also develop, especially in patients with impaired immunity.

Cause

This disease is known to be caused by tick bites.

Diagnosis

Tick exposure is often overlooked. For patients living in high-prevalence areas who spend time outdoors, a high degree of clinical suspicion should be employed. Ehrlichia serologies can be negative in the acute period. Polymerase chain reaction is therefore the laboratory diagnostic tool of choice.

Treatment

If ehrlichiosis is suspected, treatment should not be delayed while waiting for a definitive laboratory confirmation, as prompt doxycycline therapy has been associated with improved outcomes. Doxycycline is the treatment of choice.

Presentation during early pregnancy can complicate treatment. Rifampin has been used in pregnancy and in patients allergic to doxycycline.

Epidemiology

In the US, human monocytotropic ehrlichiosis occurs across the south-central, southeastern, and mid-Atlantic states, regions where both the white-tailed deer (Odocoileus virginianus) and its ectoparasite, Lone Star ticks (Amblyomma americanum), thrive.

Human monocytotropic ehrlichiosis occurs in California in Ixodes pacificus ticks and in Dermacentor variabilis ticks. Nearly 600 cases were reported to the CDC in 2006. In 2001–2002, the incidence was highest in Missouri, Tennessee, and Oklahoma, as well as in people older than 60.

See also

• Human ewingii ehrlichiosis
• Human granulocytic anaplasmosis
• Monocyte

References

1. Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology. Mosby. pp. 1130. ISBN 978-1-4160-2999-1.
2. Schutze GE, Buckingham SC, Marshall GS, et al. (June 2007). "Human monocytic ehrlichiosis in children". Pediatr. Infect. Dis. J. 26 (6): 475–9. doi:10.1097/INF.0b013e318042b66c. PMID 17529862. S2CID 1191660.
3. Zhang, Jian-zhi; Popov, Vsevolod L.; Gao, Si; Walker, David H.; Yu, Xue-jie (March 2007). "The developmental cycle of Ehrlichia chaffeensis in vertebrate cells". Cellular Microbiology. 9 (3): 610–618. doi:10.1111/j.1462-5822.2006.00812.x. PMID 16987329. S2CID 11384349.
4. Dumler JS, Choi KS, Garcia-Garcia JC, et al. (December 2005). "Human granulocytic anaplasmosis and Anaplasma phagocytophilum". Emerging Infectious Diseases. 11 (12): 1828–34. doi:10.3201/eid1112.050898. PMC 3367650. PMID 16485466.
5. Paddock CD, Folk SM, Shore GM, et al. (November 2001). "Infections with Ehrlichia chaffeensis and Ehrlichia ewingii in persons coinfected with human immunodeficiency virus". Clinical Infectious Diseases. 33 (9): 1586–94. doi:10.1086/323981. PMID 11568857.
6. "Ehrlichiosis – Transmission". United States Center for Disease Control. 17 January 2019. Retrieved November 23, 2020.
7. Prince LK, Shah AA, Martinez LJ, Moran KA (August 2007). "Ehrlichiosis: making the diagnosis in the acute setting". Southern Medical Journal. 100 (8): 825–8. doi:10.1097/smj.0b013e31804aa1ad. PMID 17713310. S2CID 31487400.
8. Hamburg BJ, Storch GA, Micek ST, Kollef MH (March 2008). "The importance of early treatment with doxycycline in human ehrlichiosis". Medicine. 87 (2): 53–60. doi:10.1097/MD.0b013e318168da1d. PMID 18344803. S2CID 2632346.
9. Muffly T, McCormick TC, Cook C, Wall J (2008). "Human granulocytic ehrlichiosis complicating early pregnancy". Infect Dis Obstet Gynecol. 2008: 1–3. doi:10.1155/2008/359172. PMC 2396214. PMID 18509484.
10. Krause PJ, Corrow CL, Bakken JS (September 2003). "Successful treatment of human granulocytic ehrlichiosis in children using rifampin". Pediatrics. 112 (3 Pt 1): e252–3. doi:10.1542/peds.112.3.e252. PMID 12949322.
11. Kennedy AC, Marshall E (2021). "Lone Star Ticks (Amblyomma americanum): An Emerging Health Threat in Delaware". Delaware Journal of Public Health. 7 (1): 66–71. doi:10.32481/djph.2021.01.013 (inactive 1 November 2024). PMC 8352541. PMID 34467183.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
12. "Ehrlichiosis: Transmission". Centers for Disease Control and Prevention. 17 January 2019. Retrieved 18 April 2024.
13. "Tickborne Diseases of the United States: Ehrlichiosis". Centers for Disease Control and Prevention. 15 December 2023. Retrieved 18 April 2024.
14. Holden K, Boothby JT, Anand S, Massung RF (July 2003). "Detection of Borrelia burgdorferi, Ehrlichia chaffeensis, and Anaplasma phagocytophilum in ticks (Acari: Ixodidae) from a coastal region of California". J. Med. Entomol. 40 (4): 534–9. doi:10.1603/0022-2585-40.4.534. PMID 14680123.
15. "Statistics and Epidemiology: Annual Cases of Ehrlichiosis in the United States". Ehrlichiosis. Division of Vector-Borne Diseases (DVBD), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention. 5 September 2013.

External links

• Bacterial diseases
• Bacterium-related cutaneous conditions
• Tick-borne diseases
• Rare infectious diseases