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ICD-10-CM 2027

ICD-10 code for Brucella infection

A23.9

Brucellosis, unspecified

✓ Billable / specificCC — complication/comorbidity

From the official ICD-10-CM alphabetic index entry “Infection, infected, infective (opportunistic) › Brucella”. Page updated September 29, 2026.

About coding Brucella infection

The ICD-10-CM code for Brucella infection is A23.9 (Brucellosis, unspecified). The official index lists 6 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on A23.9.

Within A23, choose A23.9 (unspecified) only when documentation doesn't support a more specific option: due to Brucella melitensis (A23.0), due to Brucella abortus (A23.1), due to Brucella suis (A23.2), due to Brucella canis (A23.3) and other brucellosis (A23.8).

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 867 (Other Infectious and Parasitic Diseases Diagnoses with MCC, relative weight 2.1859), DRG 868 (Other Infectious and Parasitic Diseases Diagnoses with CC, relative weight 1.0235) and DRG 869 (Other Infectious and Parasitic Diseases Diagnoses without CC/MCC, relative weight 0.6787), 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 Brucella infection codes (official index)

  • abortus A23.1 — Brucellosis due to Brucella abortus
  • canis A23.3 — Brucellosis due to Brucella canis
  • melitensis A23.0 — Brucellosis due to Brucella melitensis
  • mixed A23.8 — Other brucellosis
  • specified NEC A23.8 — Other brucellosis
  • suis A23.2 — Brucellosis due to Brucella suis

Common questions about Brucella infection ICD-10 codes

What is the ICD-10 code for Brucella infection?

A23.9 — Brucellosis, unspecified. More specific codes apply when the documentation supports them: A23.1, A23.3, A23.0, A23.8 and others below.

What is the ICD-10 code for abortus brucella infection?

A23.1 — Brucellosis due to Brucella abortus.

What is the ICD-10 code for canis brucella infection?

A23.3 — Brucellosis due to Brucella canis.

What is the ICD-10 code for melitensis brucella infection?

A23.0 — Brucellosis due to Brucella melitensis.

What is the ICD-10 code for mixed brucella infection?

A23.8 — Other brucellosis.

What is the ICD-10 code for suis brucella infection?

A23.2 — Brucellosis due to Brucella suis.

Is A23.9 billable?

Yes. A23.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can A23.9 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict A23.9 as a principal diagnosis.

Is A23.9 a CC or MCC?

A23.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.