2027 ICD-10-CM Diagnosis Code A07.9Protozoal intestinal disease, unspecified
ICD-10-CM Codes›A00–B99›A00-A09›A07
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A07.9 is a billable ICD-10-CM diagnosis code for protozoal intestinal disease, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 371 through 373. 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 67 closely related codes. Coders also document this condition as colitis caused by protozoan. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Intestinal infection; and Parasitic, other specified and unspecified infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Colitis caused by protozoan
- Disease caused by ciliate protozoa
- Intestinal ciliate infection
- Intestinal flagellate infection
- Parasitic infection causing colitis
- Parasitic infection causing inflammation of small intestine
- Protozoal enteritis of intestine
- Protozoal enteritis of small intestine
- Protozoal intestinal disease
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A07.9: its own notes plus those printed at 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.
- 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.
- Flagellate diarrhea
- Protozoal colitis
- Protozoal diarrhea
- Protozoal dysentery
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.
- 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.
- 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 A07.9, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming A07.9: they are not reported together with it, unless the two conditions are unrelated.
- A06 Amebiasisother protozoal intestinal diseases (A07.-) names A07.-, which includes this code
- Block B50-B64 Protozoal diseasesother protozoal intestinal diseases (A07.-) names A07.-, which includes this code
Excludes2 2
These codes carry an Excludes2 note naming A07.9: its condition is not part of those codes, and both may be reported when the patient has both.
- Block P35-P39 Infections specific to the perinatal period
- P37 Other congenital infectious and parasitic diseases
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic) See Also: Enteritis; K52.9
protozoal A07.9
Disease, diseased See Also: Syndrome;
Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical) A09
protozoal A07.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Gastroenteritis
Gastroenteritis is an inflammation of the lining of the stomach and intestines. The main symptoms include vomiting and diarrhea. It is usually not serious in healthy people, but it can sometimes lead to dehydration or cause severe symptoms.
The full article covers:
- What is gastroenteritis?
- What causes gastroenteritis?
- What are the symptoms of gastroenteritis?
- How is gastroenteritis diagnosed?
- What are the treatments for gastroenteritis?
- Can gastroenteritis be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A07.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A07.9Overview
What is the ICD-10 code for protozoal intestinal disease, unspecified?
The ICD-10-CM code for protozoal intestinal disease, unspecified is A07.9 (sometimes written as A079). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A07.9 (Other protozoal intestinal diseases) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report protozoal intestinal disease, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A07.9 group to?
When protozoal intestinal disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 372, 371, 373, with relative weights from 0.6945 to 1.7087 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A07.9 a CC or MCC?
CMS lists A07.9 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 67 closely related codes in its exclusion list.
What is the ICD-9 equivalent of A07.9?
Under the General Equivalence Mappings, protozoal intestinal disease, unspecified converts to ICD-9-CM 007.9 (protozoal intest dis NOS). The mapping is a direct match.
