2026 ICD-10-CM Diagnosis Code B77.81Ascariasis pneumonia

ICD-10-CM Codes›A00–B99›B65-B83›B77

ICD-10-CM B77.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B77.81 is a billable ICD-10-CM diagnosis code for ascariasis pneumonia. 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. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 145 closely related codes. Coders also document this condition as ascariasis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections; and Pneumonia (except that caused by tuberculosis).

Code Identity

ICD-10-CM Code
B77.81
Billable Status
Yes — Valid for Submission
Code Describes
Ascariasis pneumonia
Short Description
Ascariasis pneumonia
Same as the full description in the CMS dataset.
Parent Code
B77.8
Ascariasis with other complications

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB65-B83Helminthiases
CategoryB77Ascariasis
This CodeB77.81Ascariasis pneumonia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Ascariasis
  • Pneumonia caused by Ascaris
  • Pneumonia due to parasitic infestation
  • Pulmonary nematodiasis

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 No · outpatient No
CCSR RSP002
Pneumonia (except that caused by tuberculosis)
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 B77.81 to ICD-9-CMHistory

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

ICD-9-CM
127.0 Ascariasis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
484.8 Pneum in infect dis NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 B77.81Overview

What is the ICD-10 code for ascariasis pneumonia?

The ICD-10-CM code for ascariasis pneumonia is B77.81 (sometimes written as B7781). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is B77.81 (Ascariasis with other complications) a billable code?

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

What MS-DRG does B77.81 group to?

When ascariasis pneumonia 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.

Is B77.81 a CC or MCC?

CMS lists B77.81 as an MCC (major complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 145 closely related codes in its exclusion list.

What is the ICD-9 equivalent of B77.81?

Under the General Equivalence Mappings, ascariasis pneumonia converts to ICD-9-CM 127.0 (ascariasis) and 484.8 (pneum in infect dis NEC). The mapping is approximate, so confirm the match fits the documentation.