ICD-10 Code A79.0 – Trench fever (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A79.0 – Trench fever
What it is
A79.0 identifies trench fever, a bacterial infection caused by Bartonella quintana. It is typically associated with body lice exposure and can affect people in crowded or unsanitary living conditions.
Clinical signs
Common findings include recurring fever, headache, bone pain, and fatigue. Clinical features vary; refer to documentation, especially if the record notes louse exposure or recurrent febrile episodes.
When to use this code
Use A79.0 when the provider documents trench fever or confirms Bartonella quintana infection consistent with that diagnosis. Apply it when the record links the illness to the classic exposure history or recognized clinical picture. If the documentation only says fever without a specific cause, do not assume this code.
Do not use for
Do not use this code for nonspecific febrile illness, typhus, or other Bartonella infections without documentation of trench fever. Check documentation if the diagnosis is uncertain or incomplete.
Coding tip
Code A79.0 only when trench fever is explicitly documented; otherwise, query for the specific infectious diagnosis.