ICD-10-CM 2027
ICD-10 code for retrovirus infection
From the official ICD-10-CM alphabetic index entry “Infection, infected, infective (opportunistic) › retrovirus”. Page updated September 29, 2026.
About coding retrovirus infection
The ICD-10-CM code for retrovirus infection is B33.3 (Retrovirus infections, not elsewhere classified). The official index lists 7 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on B33.3.
Within B33 (other viral diseases, not elsewhere classified), B33.3 is specifically for retrovirus infections, not elsewhere classified. Related codes cover epidemic myalgia (B33.0), Ross River disease (B33.1), viral carditis (B33.2), Hantavirus (cardio)-pulmonary syndrome [HPS] [HCPS] (B33.4) and other specified viral diseases (B33.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
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.
More specific retrovirus infection codes (official index)
- as cause of disease classified elsewhere B97.30 — Unspecified retrovirus as the cause of diseases classified elsewhere
- human
- immunodeficiency, type 2 (HIV 2) B97.35 — Human immunodeficiency virus, type 2 [HIV 2] as the cause of diseases classified elsewhere
- T-cell lymphotropic
- type I (HTLV-I) B97.33 — Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere
- type II (HTLV-II) B97.34 — Human T-cell lymphotrophic virus, type II [HTLV-II] as the cause of diseases classified elsewhere
- lentivirus B97.31 — Lentivirus as the cause of diseases classified elsewhere
- oncovirus B97.32 — Oncovirus as the cause of diseases classified elsewhere
- specified NEC B97.39 — Other retrovirus as the cause of diseases classified elsewhere
Common questions about retrovirus infection ICD-10 codes
What is the ICD-10 code for retrovirus infection?
- B33.3 — Retrovirus infections, not elsewhere classified. More specific codes apply when the documentation supports them: B97.30, B97.35, B97.33, B97.34 and others below.
Is B33.3 billable?
- Yes. B33.3 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can B33.3 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict B33.3 as a principal diagnosis.
Is B33.3 a CC or MCC?
- No. B33.3 is neither a CC nor an MCC under MS-DRG v44.0.