2026 ICD-10-CM Diagnosis Code A07.3Isosporiasis

ICD-10-CM Codes›A00–B99›A00-A09›A07

ICD-10-CM A07.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A07.3 is a billable ICD-10-CM diagnosis code for isosporiasis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 371 through 373, 974 through 976. 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 Cystoisospora
  • Infection by Isospora hominis
  • Infection caused by Blastocystis
  • Infection caused by Coccidia co-occurrent with acquired immunodeficiency syndrome
  • 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

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

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

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Coccidiosis(intestinal)
    • Colitis(acute) (catarrhal) (chronic) (noninfective) (hemorrhagic)
      • coccidial
    • Diarrhea, diarrheal(disease) (infantile) (inflammatory)
      • coccidial
    • Dysentery, dysenteric(catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)
      • coccidial
    • Enteritis(acute) (diarrheal) (hemorrhagic) (noninfective)
      • coccidial
    • Infection, infected, infective(opportunistic)
      • Isospora belli or hominis
    • Infestation
      • coccidial
    • Isosporiasis, isosporosis

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.

  • Coccidiosis

    protozoan infection found in animals and man. it is caused by several different genera of coccidia.

  • Isospora

    a genus of protozoan parasites found in the intestines of birds, amphibians, reptiles, and mammals, including man. the oocysts produce two sporocysts, each with four sporozoites. many species are parasitic in wild and domestic animals.

  • Coccidia

    a subclass of protozoans commonly parasitic in the epithelial cells of the intestinal tract but also found in the liver and other organs. its organisms are found in both vertebrates and higher invertebrates and comprise two orders: eimeriida and eucoccidiida.

  • Coccidiosis

    a parasitic infection caused by coccidia. it affects livestock, birds and humans. in humans the parasite infests the intestinal tract and may cause watery diarrhea, abdominal pain, fever, nausea and vomiting.

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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A07.3Overview

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, 2025 through September 30, 2026.

What MS-DRG does A07.3 group to?

When isosporiasis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 371, 372, 373, 974, 975, 976, with relative weights from 0.7274 to 2.8860 depending on complications. Higher weights mean higher Medicare reimbursement.

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.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.