2026 ICD-10-CM Diagnosis Code B77.9Ascariasis, unspecified

ICD-10-CM Codes›A00–B99›B65-B83›B77

ICD-10-CM B77.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B77.9 is a billable ICD-10-CM diagnosis code for ascariasis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. Coders also document this condition as ascariasis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
B77.9
Billable Status
Yes — Valid for Submission
Code Describes
Ascariasis, unspecified
Short Description
Ascariasis, unspecified
Same as the full description in the CMS dataset.
Parent Code
B77
Ascariasis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB65-B83Helminthiases
CategoryB77Ascariasis
This CodeB77.9Ascariasis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Ascariasis
  • Ascariasis caused by adult Ascaris
  • Infection by Ascaridia
  • Infection by Ascaridia dissimilis
  • Infection by Ascaridia galli
  • Infection by Ascaris lumbricoides
  • Infection by Ascaris suum
  • Migratory ascariasis

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.

    • Ascariasis
    • Infection, infected, infective(opportunistic)
      • roundworm (large) NEC
        • Ascariasis
    • Infestation
      • roundworm (large) NEC
        • Ascariasis
    • Round
      • worms (large) (infestation) NEC
        • Ascariasis

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

Clinical InformationClinical

  • Ascariasis

    infection by nematodes of the genus ascaris. ingestion of infective eggs causes diarrhea and pneumonitis. its distribution is more prevalent in areas of poor sanitation and where human feces are used for fertilizer.

  • Ascaris

    a genus of nematodes of the superfamily ascaridoidea whose species usually inhabit the intestine.

  • Ascariasis

    an infection that is caused by the roundworm ascaris lumbricoides, many cases of which remain asymptomatic. during the transient larval migratory phase, shortness of breath, fever, and eosinophilia can occur. depending on the intestinal worm burden, a spectrum of gastrointestinal tract symptoms can occur.

  • Baylisascariasis|Raccoon Roundworm Infection

    an infection that is caused by the raccoon nematode baylisascaris procyonis, which is transmitted by the ingestion of embryonated eggs in contaminated soil; symptoms depend on larval migration sites (visceral organs, eye, or brain) provoking severe inflammatory responses.

Patient EducationClinical

Parasitic Diseases

Parasites are living things that use other living things - like your body - for food and a place to live. You can get them from contaminated food or water, a bug bite, or sexual contact. Some parasitic diseases are easily treated and some are not.

Read the full article at MedlinePlus

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

Convert B77.9 to ICD-9-CMHistory

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

ICD-9-CM
127.0 Ascariasis
Approximate The match is approximate rather than exact.

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 B77.9Overview

Is B77.9 (Ascariasis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report ascariasis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B77.9 group to?

When ascariasis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B77.9?

Under the General Equivalence Mappings, ascariasis, unspecified converts to ICD-9-CM 127.0 (ascariasis). The mapping is approximate, so confirm the match fits the documentation.

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.