2027 ICD-10-CM Diagnosis Code A07.3Isosporiasis

ICD-10-CM Codes›A00–B99›A00-A09›A07

ICD-10-CM A07.3
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A07.3 is a billable ICD-10-CM diagnosis code for isosporiasis. 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, 974 through 976. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Intestinal infection; and Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
A07.3
Billable Status
Yes — Valid for Submission
Code Describes
Isosporiasis
Short Description
Isosporiasis
Same as the full description in the CMS dataset.
Parent Code
A07
Other protozoal intestinal diseases

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA00-A09Intestinal infectious diseases
CategoryA07Other protozoal intestinal diseases
This CodeA07.3Isosporiasis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Blastocystis hominis infection
  • Chronic intestinal isosporiasis
  • Coccidiosis
  • Coccidiosis co-occurrent with human immunodeficiency virus infection
  • Colitis caused by protozoan
  • Disease caused by Eimeriidae
  • Disorder of gastrointestinal tract co-occurrent with human immunodeficiency virus infection
  • Enteric coccidiosis
  • Hepatic coccidiosis
  • Human coccidiosis
  • Infection by Isospora hominis
  • Infection caused by Blastocystis
  • Infection caused by Coccidia co-occurrent with acquired immunodeficiency syndrome
  • Infection caused by Cystoisospora
  • Infection caused by Cystoisospora belli
  • Infection caused by Isospora co-occurrent with acquired immunodeficiency syndrome
  • Isosporiasis
  • Isosporiasis co-occurrent with human immunodeficiency virus infection
  • Parasitic infection causing colitis
  • Parasitic infection causing inflammation of small intestine
  • Parasitic infection of colon caused by Cystoisospora belli
  • Parasitic infection of small intestine caused by Cystoisospora belli
  • Protozoal enteritis of small intestine
  • Renal coccidiosis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A07.3: 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.

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.

  • Infection due to Isospora belli and Isospora hominis
  • Intestinal coccidiosis
  • Isosporosis

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 A07.3, its category, or a range that includes it.

Excludes1 3

These codes carry an Excludes1 note naming A07.3: they are not reported together with it, unless the two conditions are unrelated.

  • B60 Other protozoal diseases, not elsewhere classified
    isosporiasis (A07.3)
  • A06 Amebiasis
    other protozoal intestinal diseases (A07.-) names A07.-, which includes this code
  • Block B50-B64 Protozoal diseases
    other protozoal intestinal diseases (A07.-) names A07.-, which includes this code

Excludes2 2

These codes carry an Excludes2 note naming A07.3: 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
    intestinal infectious disease (A00-A09) names A00-A09, which includes this code
  • P37 Other congenital infectious and parasitic diseases
    infectious neonatal diarrhea (A00-A09) names A00-A09, 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 DIG001
Intestinal infection
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Isosporiasis

    infection with parasitic protozoa of the genus isospora, producing intestinal disease. it is caused by ingestion of oocysts and can produce tissue cysts.

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 A07.3 to ICD-9-CMHistory

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

ICD-9-CM
007.2 Coccidiosis
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 A07.3Overview

What is the ICD-10 code for isosporiasis?

The ICD-10-CM code for isosporiasis is A07.3 (sometimes written as A073). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A07.3 (Other protozoal intestinal diseases) a billable code?

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

What MS-DRG does A07.3 group to?

When isosporiasis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 372, 974, 976, 975, 371, 373, with relative weights from 0.6945 to 3.0488 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A07.3 a CC or MCC?

CMS lists A07.3 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 A07.3?

Under the General Equivalence Mappings, isosporiasis converts to ICD-9-CM 007.2 (coccidiosis). The mapping is a direct match.