Blood Smear Uncovers Tick-Borne Infection

Peripheral blood smear and PCR findings identify anaplasmosis complicated by myocarditis

July 20, 2026
3 min

The Pathologist

Overview

This case report highlights the diagnosis of tick-borne anaplasmosis in a 79-year-old man who developed acute myocarditis. Laboratory findings, including a peripheral blood smear and PCR testing, were crucial for diagnosis and treatment.

Background

Anaplasma phagocytophilum infection can present with nonspecific symptoms and lead to complications, including myocarditis, particularly in older or immunocompromised patients. Understanding the clinical presentation and laboratory findings associated with anaplasmosis is essential for diagnosis and management.

Data Highlights

No numerical data or trial data were provided in the source material.

Key Findings

A 79-year-old man presented with fatigue, chills, and weakness, leading to a diagnosis of anaplasmosis.
Initial laboratory tests revealed lymphopenia, thrombocytopenia, and elevated liver enzymes.
A peripheral blood smear showed intracytoplasmic morulae, indicating anaplasmosis.
Polymerase chain reaction (PCR) testing confirmed the presence of A. phagocytophilum.
The patient developed acute myocarditis, confirmed by elevated troponin levels and imaging studies.
Treatment with doxycycline led to clinical improvement and normalization of cardiac function.

Clinical Implications

Anaplasmosis should be considered in patients with febrile illness and compatible laboratory findings, particularly in endemic areas.

Conclusion

This case highlights the importance of considering tick-borne infections in differential diagnoses for febrile illnesses and the role of laboratory testing in facilitating treatment.