ICD-10 Code B51 – Plasmodium vivax malaria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B51 – Plasmodium vivax malaria
What it is
B51 identifies malaria caused by Plasmodium vivax, a parasitic infection transmitted by infected mosquitoes. Use this code when the record specifically names P. vivax malaria.
Clinical signs
Typical findings include fever, chills, sweats, headache, malaise, and sometimes splenomegaly. Clinical features vary; refer to documentation for the confirmed species and presentation.
When to use this code
Use B51 when the clinician documents Plasmodium vivax malaria or confirms the organism by testing. It is appropriate for acute infection, recurrent episodes, or follow-up visits tied to the same documented diagnosis. If the species is not stated, check documentation before assigning this code.
Do not use for
Do not use B51 for malaria caused by another Plasmodium species or when malaria is only suspected. If the chart says “malaria” without species identification, you need the documented organism first.
Coding tip
Code B51 only when P. vivax is explicitly documented; otherwise, query the provider for clarification.