Objective:

To highlight the importance of laboratory findings and early molecular testing in diagnosing tick-borne anaplasmosis, particularly in a patient with acute myocarditis.

Approach:

• Case Presentation: A 79-year-old man presented with fatigue, chills, weakness, and a fall, leading to initial laboratory testing.
• Diagnostic Testing: Peripheral blood smear revealed intracytoplasmic morulae, and PCR confirmed Anaplasma phagocytophilum.
• Clinical Progression: The patient developed hypoxia and acute myocarditis, confirmed by elevated troponin and imaging studies.
• Treatment and Outcome: Doxycycline treatment led to rapid improvement in clinical condition and normalization of cardiac function at follow-up.

Key Findings:

• Anaplasma phagocytophilum infection should be considered in patients with unexplained febrile illness and laboratory abnormalities.
• Characteristic laboratory findings include thrombocytopenia, lymphopenia, elevated liver enzymes, and acute kidney injury.
• Peripheral blood smear can provide a rapid presumptive diagnosis when neutrophil morulae are identified.

Interpretation:

Limitations:

• The case report is based on a single patient, limiting generalizability.
• The report does not address the long-term outcomes of anaplasmosis in other populations.

Conclusion:

Anaplasmosis should remain in the differential diagnosis for unexplained febrile illness in endemic areas, with early laboratory recognition and treatment being vital.

Sources:

• CMAJ Case Report