A48.1 — Legionnaires' disease
Is A48.1 billable?
Yes — A48.1 is billable for FY2027. A48.1 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. A48.1 may be submitted for encounters from October 1, 2026 through September 30, 2027.
A48.1 at a glance
| Code | A48.1 |
|---|---|
| Description | Legionnaires' disease |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does A48.1 group to?
A48.1 sits in MDC 04 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 177Respiratory Infections and Inflammations with MCCmedical
- 178Respiratory Infections and Inflammations with CCmedical
- 179Respiratory Infections and Inflammations without CC/MCCmedical
As a secondary diagnosis, A48.1 is a major complication or comorbidity (MCC), which can move a stay into a higher-paying DRG.
How is A48.1 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to A48.1. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Legionellosis
- Disease, diseased › legionnaires'
- Infection, infected, infective › Legionella pneumophila (opportunistic)
- Legionnaires' › disease
- Legionnaires' › pneumonia
Excludes1 — never code together — inherited from A48
The conditions below can never be reported together with A48.1 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- actinomycetoma (B47.1)
Use additional code — inherited from Chapter 1
Report an additional code alongside A48.1 to fully describe the condition. A48.1 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of A48.1, but a patient may have both at the same time. When documentation supports it, A48.1 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
How long has A48.1 existed?
A48.1 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with A48.1?
ICD-10-CM declares these codes mutually exclusive with A48.1 — exactly one of each pair can be correct for a given encounter.