A49 vs A79.9
A49 and A79.9 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on A49
rickettsial infection NOS (A79.9)
A49
Bacterial infection of unspecified site
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A30-A49
A79.9
Rickettsiosis, unspecified
BillableUnspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A75-A79
Use when the record says
- Rickettsial infection NOS
Indexed under
- Rickettsial disease
- Rickettsiosis
- Disease, diseased › rickettsial NOS
- Infection, infected, infective › rickettsial NOS (opportunistic)
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027