Ehrlichiosis and Anaplasmosis

These conditions are zoonotic tick-borne diseases caused by rickettsial organisms of the genera Ehrlichia and Anaplasma, with broad worldwide distribution in animal and human populations ^[1][2]. Human granulocytic anaplasmosis specifically refers to bacterial infection by Anaplasma phagocytophilum transmitted through tick bites ^[3].

In humans, granulocytic anaplasmosis presents with fever, chills, headache, and myalgia after a 5- to 14-day incubation following tick attachment ^[3]. Equine granulocytic anaplasmosis commonly manifests as high fever and edema with mild to moderate thrombocytopenia and lymphopenia, while subclinical or self-limiting cases occur and rare neurologic or vasculitic presentations are reported ^[4]. Canine and feline forms are recognized as clinically manageable zoonotic infections, though specific signs in these species are not detailed in the available evidence ^[1].

Canine ehrlichiosis and anaplasmosis show high prevalence in dogs across multiple European countries, with publications and surveillance data increasing in recent years ^[2]. Human granulocytic anaplasmosis is expanding in North America with growing incidence and is transmitted by black-legged ticks ^[3]. Equine granulocytic anaplasmosis has broader prevalence in equids than formerly appreciated ^[4]. The organisms involved have demonstrated expanding geographic distribution affecting dogs, cats, people, and horses ^[1][2].

The diseases are transmitted by tick vectors, with human granulocytic anaplasmosis acquired via black-legged (deer tick) bite after 24 to 48 hours of attachment ^[3]. Canine and feline ehrlichiosis and anaplasmosis are similarly tick-borne zoonoses with broad distribution ^[1][2]. Blood specimen microscopy and PCR can detect active human infection, reflecting tick exposure as the primary route ^[3][5].

No vaccines are currently available to protect against ehrlichiosis or anaplasmosis in any host ^[1]. Prevention relies on avoidance of tick exposure and vector control, as emphasized in veterinary practitioner guidelines for European dogs and in reviews of tick-borne infection control ^[2][5]. Specific behavioral or chemopreventive interventions beyond tick-bite avoidance are not described in the supplied evidence ^[1][2].

1. 1 Diniz PPVP et al. Ehrlichiosis and Anaplasmosis: An Update. Vet Clin North Am Small Anim Pract. 2022 Nov. PMID: 36336419. doi: 10.1016/j.cvsm.2022.07.002. PubMed: https://pubmed.ncbi.nlm.nih.gov/36336419/
2. 2 Sainz Á et al. Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasit Vectors. 2015 Feb 4. PMID: 25649069. doi: 10.1186/s13071-015-0649-0. PubMed: https://pubmed.ncbi.nlm.nih.gov/25649069/
3. 3 MacQueen D et al. Human Granulocytic Anaplasmosis. Infect Dis Clin North Am. 2022 Sep. PMID: 36116840. doi: 10.1016/j.idc.2022.02.008. PubMed: https://pubmed.ncbi.nlm.nih.gov/36116840/
4. 4 Oliver A et al. Equine Granulocytic Anaplasmosis. Vet Clin North Am Equine Pract. 2023 Apr. PMID: 36737288. doi: 10.1016/j.cveq.2022.11.011. PubMed: https://pubmed.ncbi.nlm.nih.gov/36737288/
5. 5 Sanchez E et al. Diagnosis, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: A Review. JAMA. 2016 Apr 26. PMID: 27115378. doi: 10.1001/jama.2016.2884. PubMed: https://pubmed.ncbi.nlm.nih.gov/27115378/