American canine hepatozoonosis

Area of Science:

• Veterinary Parasitology
• Infectious Diseases
• Tick-borne Illnesses

Background:

• American canine hepatozoonosis (ACH) is a debilitating and often fatal tick-borne disease prevalent in the southeastern and south-central United States.
• The disease is caused by the apicomplexan parasite Hepatozoon americanum, distinct from the Old World pathogen Hepatozoon canis.
• ACH is transmitted through the ingestion of infected Gulf Coast ticks (Amblyomma maculatum).

Purpose of the Study:

• To review the biology of Hepatozoon americanum and its vector, Amblyomma maculatum.
• To differentiate American canine hepatozoonosis from classical canine hepatozoonosis (H. canis).
• To examine the clinical presentation, diagnosis, treatment, and epidemiology of ACH.

Main Methods:

• Literature review of existing studies on Hepatozoon americanum and canine hepatozoonosis.
• Comparative analysis of ACH and H. canis transmission cycles and hosts.
• Discussion of clinical findings, diagnostic approaches, and therapeutic strategies for ACH.

Main Results:

• Hepatozoon americanum is transmitted by Gulf Coast ticks, with dogs as accidental hosts, unlike H. canis transmitted by brown dog ticks.
• ACH is characterized by leukocytosis and periosteal bone proliferation, leading to severe clinical signs.
• The geographic distribution of ACH aligns with the expanding range of the Gulf Coast tick.

Conclusions:

• The endemic cycle of H. americanum involves A. maculatum and unidentified vertebrate hosts.
• Further research is needed to identify intermediate hosts and understand the role of coyotes in maintaining the ACH cycle.
• ACH presents unique biological and epidemiological features, offering potential as a model for studying angiogenesis and hypertrophic osteoarthropathy.