Ehrlichia canis

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Ehrlichia canis
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Alphaproteobacteria
Order: Rickettsiales
Family: Ehrlichiaceae
Genus: Ehrlichia
Species:
E. canis
Binomial name
Ehrlichia canis
(Donatien and Lestoquard 1935) Moshkovski 1945[1][2]

Ehrlichia canis is an

causative agent of ehrlichiosis, a disease most commonly affecting canine species. This pathogen is present throughout the United States (but is most prominent in the South),[3] South America, Asia, Africa and recently in the Kimberley region of Australia.[4][5] First defined in 1935, E. canis emerged in the United States in 1963 and its presence has since been found in all 48 contiguous United States.[3][6] Reported primarily in dogs, E. canis has also been documented in felines and humans, where it is transferred most commonly via Rhipicephalus sanguineus, the brown dog tick.[3]

Transmission cycle

The brown dog tick, R. sanguineus, acts as the

reservoir hosts for this pathogen and are the primary hosts of brown dog ticks. Brown dog ticks become carriers of the pathogen when they take a blood meal from a rickessemic dog. Stored in the midgut and salivary glands of an infected tick, E. canis is transferred by the saliva of ticks carrying the pathogen to hosts during blood meals.[3] If infected while in the larval stage, the tick retains the pathogen through the next two life stages and can infect hosts during blood meals in both the nymphal and adult stages in transstadial transmission.[4]

Because the vector of E. canis uses canine species as a

primary host, this bacterium is most commonly associated with dogs, but multiple human cases have been reported.[7] Additionally, some cats have been found to have antibodies to E. canis suggesting that it can occasionally infect cats, as well.[8][9]

Pathogenesis

E. canis is a small, coccus bacterium with a single circular chromosome. Minute in size, E. canis is smaller than the other species in the genus Ehrlichia.[8][10]

The

antibodies in its host organism's body.[10]

The cells of E. canis lack complex internal structures, which allow the synthesis of sugars and it, in turn, uses amino acids as its source of energy.[10]

Upon introduction, E. canis penetrates the monocytes and macrophages of hosts. Infection may leave a host asymptomatic for months or severe clinical signs may manifest as ehrlichiosis develops.[11]

Diagnosis and treatment

Animals infected with E. canis may experience a combination of signs, including fever, lethargy, weight loss, lymphadenopathy, edema of the appendages, discharge from nose and eyes, and seizures.[4][6][11] A low packed cell volume in the blood is a common indicator of the presence of E. canis and a blood smear can be done to determine if morulae are present in leukocytes to definitively diagnose the infection. Because this process is often long and tedious, the presence of antibodies to E. canis in blood can be used to effectively diagnose a patient. These antibodies typically appear within seven days after infection.[4][6]

E. canis is commonly treated via chemoprophylaxis with doxycycline, a prescription drug used in the treatment of bacterial infections. If caught before the clinical stage, E. canis is almost completely curable, but prolonged presence of the bacteria leads to hemorrhaging, which typically results in the death of the patient.[3]

Although no

clinical signs and the presence of the E. canis bacteria were reduced in Beagle test subjects, but further investigations are necessary before a vaccine can be marketed.[12]

References

  1. LPSN
    .
  2. ^ "Ehrlichia Canis" at the Encyclopedia of Life
  3. ^
    PMID 19150176
    .
  4. ^ a b c d Jeanine, Peters (Winter 2000). "Canine Ehrlichiosis". ADDL Diagnostic Forum Newsletter.
  5. ^ "Kimberley Dog Controlled Area – dog movement conditions". Government of Western Australia, Department of Primary Industries and Regional Development, Agriculture and Food division. June 4, 2020. Retrieved June 4, 2020.
  6. ^
    PMID 20933140
    .
  7. S2CID 28743204
    .
  8. ^ a b Morgan, Rhea. "Ehrlichiosis in Cats". Retrieved 2013-10-31.
  9. PMID 25242952
    .
  10. ^
    PMID 16707693
    .
  11. ^ a b "Erlichia Canis in Dogs". Archived from the original on 9 September 2013. Retrieved 2013-10-25.
  12. PMID 23072894
    .
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