2027 ICD-10-CM Diagnosis Code A75.9Typhus fever, unspecified

ICD-10-CM Codes›A00–B99›A75-A79›A75

ICD-10-CM A75.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A75.9 is a billable ICD-10-CM diagnosis code for typhus fever, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 211 closely related codes. Coders also document this condition as typhus group rickettsial disease. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
A75.9
Billable Status
Yes — Valid for Submission
Code Describes
Typhus fever, unspecified
Short Description
Typhus fever, unspecified
Same as the full description in the CMS dataset.
Parent Code
A75
Typhus fever

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA75-A79Rickettsioses
CategoryA75Typhus fever
This CodeA75.9Typhus fever, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Typhus group rickettsial disease

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A75.9: its own notes plus those printed at A75 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Typhus (fever) NOS

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From A75 Typhus fever applies to 5 codes
  • rickettsiosis due to Ehrlichia sennetsu (A79.81)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • 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)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name A75.9, its category, or a range that includes it.

Code First 1

These codes say to code first a condition named in the note, and A75.9 is one of the conditions named.

  • I41 Myocarditis in diseases classified elsewhere
    typhus (A75.0-A75.9) names A75.0-A75.9, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A75.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
081.9 Typhus NOS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A75.9Overview

What is the ICD-10 code for typhus fever, unspecified?

The ICD-10-CM code for typhus fever, unspecified is A75.9 (sometimes written as A759). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A75.9 (Typhus fever) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report typhus fever, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does A75.9 group to?

When typhus fever, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A75.9 a CC or MCC?

CMS lists A75.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 211 closely related codes in its exclusion list.

Can A75.9 be reported with A79.81?

Not as a rule. The Excludes1 note at A75, which applies to A75.9, lists "rickettsiosis due to Ehrlichia sennetsu (A79.81)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).