B51.9 Plasmodium vivax malaria without complication

The ICD-10-CM code for Plasmodium vivax malaria without complication is B51.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

1: Certain infectious and parasitic diseases (A00-B99)

Section

B50-B64: Protozoal diseases (B50-B64)

Category B51

4 codes (3 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to B51.9:

• Malaria, malarial (fever) › vivax
• Malaria, malarial (fever) › Plasmodium (P.) › vivax NEC

Inclusion Terms

• Plasmodium vivax malaria NOS

U.S. Hospital Utilization

• An estimated 125 U.S. inpatient stays in 2023 included B51.9 among the documented diagnoses.
• 75 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

HIV Infections (TOC entry)

a. Human Immunodeficiency Virus (HIV) Infections .............................................................. 19

Infectious agents causing diseases in other chapters (TOC)

b. Infectious agents as the cause of diseases classified to other chapters ................................. 22

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)