ICD-10 code for rickettsiosis

The ICD-10-CM code for rickettsiosis is A79.9 (Rickettsiosis, 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 A79.9.

Within A79, choose A79.9 (Rickettsiosis, unspecified) only when documentation doesn't support a more specific option: Trench fever (A79.0), Rickettsialpox due to Rickettsia akari (A79.1) and other specified rickettsioses (A79.8).

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.