ICD-10-CM 2027
ICD-10 code for Ross River fever
From the official ICD-10-CM alphabetic index entry “Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › Ross River”. Page updated September 29, 2026.
About coding Ross River fever
The ICD-10-CM code for Ross River fever is B33.1 (Ross River disease).
Within B33 (other viral diseases, not elsewhere classified), B33.1 is specifically for Ross River disease. Related codes cover epidemic myalgia (B33.0), viral carditis (B33.2), retrovirus infections, not elsewhere classified (B33.3), Hantavirus (cardio)-pulmonary syndrome [HPS] [HCPS] (B33.4) and other specified viral diseases (B33.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 865 (Viral Illness with MCC, relative weight 1.3485) and DRG 866 (Viral Illness without MCC, relative weight 0.8692), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about Ross River fever ICD-10 codes
What is the ICD-10 code for Ross River fever?
- B33.1 — Ross River disease.
Is B33.1 billable?
- Yes. B33.1 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can B33.1 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict B33.1 as a principal diagnosis.
Is B33.1 a CC or MCC?
- B33.1 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.