Introduction

Classification

Taxonomy

• Phylum: Apicomplexa.
• Class: Sporozoa.
• Subclass: Coccidia.
• Order: Euccidiidae.
• Family: Haemogregarinidae.
• Genus: Hepatozoon.
• Species: felis.

Etymology

• Gr: heparo - liver; zoion - animal.

Clinical Effects

Epidemiology

Habitat

• In the tick (Rhipicephalus sanguineus).

Lifecycle

• Cats ingest infected tick   →   sporozoites in tick released by digestive enzymes   →   sporozoites penetrate intestinal wall   →   schizogony in reticuloendothelial cells   →   macroschizonts   →   macromerozoites   →   reinfect reticuolendothelial cells of spleen, bone marrow, liver, lungs and muscles   →   microschizonts and micromerozoites   →   micromerozoites infect blood monocytes and neutrophils   →   form gametocytes   →   ingested by tick   →   oocysts in body cavity of tick   →   sporulate   →   infective sporozoites.

Transmission

• By ingestion of an infected tick.

Pathological effects

• Schizonts, sporozoites and merozoites infect monocytes, neutrophils and cells of the reticuloendothelial system.
• Micromerozoites stimulate granulomatous inflammation.

• Few reports in cats.
• Micromerozoites in liver may cause granulomatous cholangiohepatitis.
• Clinical signs: recurrent fever, loss of condition and lumbar pain.

Other Host Effects

• May cause subclinical infection in some hosts.

• H. felis is probably the same organism as H. canis.

Control

Control via animal

• Control of ticks.

Control via chemotherapies

• Combination of primaquine and oxytetracycline Oxytetracycline.
• Palliative treatment with non-steroidal anti-inflammatory drugs.

Control via environment

• Control of ticks.

Vaccination

• None available.

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Lloret A, Addie D D, Boucraut-Baralon C et al (2015) Hepatozoonosis in cats: ABCD guidelines on prevention and management. J Feline Med Surg 17 (7), 642-644 PubMed.
• Ewing G O (1977) Granulomatous cholangiohepatitis in a cat due to a protozoan parasite resembling Hepatozoon canis. Feline Practice 7 (6), 37-40 VetMedResource.
• Klopfer U, Nobel T A, Neumann F (1973) Hepatozoon-like parasite (schizonts) in the myocardium of the domestic cat. Veterinary Pathology 10 (3), 185-190 PubMed.