2027 ICD-10-CM Diagnosis Code B50.9Plasmodium falciparum malaria, unspecified

ICD-10-CM Codes›A00–B99›B50-B64›B50

ICD-10-CM B50.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

B50.9 is a billable ICD-10-CM diagnosis code for plasmodium falciparum malaria, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. 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 32 closely related codes. Coders also document this condition as algid malaria. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
B50.9
Billable Status
Yes — Valid for Submission
Code Describes
Plasmodium falciparum malaria, unspecified
Short Description
Plasmodium falciparum malaria, unspecified
Same as the full description in the CMS dataset.
Parent Code
B50
Plasmodium falciparum malaria

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB50-B64Protozoal diseases
CategoryB50Plasmodium falciparum malaria
This CodeB50.9Plasmodium falciparum malaria, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Algid malaria
  • Chagres virus disease
  • Double quotidien fever
  • Falciparum malaria
  • Intermittent fever
  • Malarial fever
  • Malignant tertian fever
  • Quotidien fever
  • Tertian fever

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to B50.9: its own notes plus those printed at B50, block B50-B64, and 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 B50 Plasmodium falciparum malaria applies to 3 codes
  • mixed infections of Plasmodium falciparum with any other Plasmodium species
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block B50-B64 Protozoal diseases applies to 57 codes
  • amebiasis (A06.-)
  • other protozoal intestinal diseases (A07.-)

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 B50.9, its category, or a range that includes it.

Applicable To 1

These notes mention B50.9.

  • O98.6 Protozoal diseases complicating pregnancy, childbirth and the puerperium
    Conditions in B50-B64 names B50-B64, which includes this code

Excludes1 4

These codes carry an Excludes1 note naming B50.9: they are not reported together with it, unless the two conditions are unrelated.

  • B51 Plasmodium vivax malaria
    plasmodium vivax with Plasmodium falciparum (B50.-) names B50.-, which includes this code
  • B52 Plasmodium malariae malaria
    Plasmodium falciparum (B50.-) names B50.-, which includes this code
  • B53.0 Plasmodium ovale malaria
    Plasmodium ovale with Plasmodium falciparum (B50.-) names B50.-, which includes this code
  • B53.1 Malaria due to simian plasmodia
    Malaria due to simian plasmodia with Plasmodium falciparum (B50.-) names B50.-, which includes this code

Code First 2

These codes say to code first a condition named in the note, and B50.9 is one of the conditions named.

  • D63.8 Anemia in other chronic diseases classified elsewhere
    malaria (B50.0-B54) names B50.0-B54, which includes this code
  • D77 Other disorders of blood and blood-forming organs in diseases classified elsewhere
    malaria (B50.0-B54) names B50.0-B54, 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 INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Malaria, Falciparum

    malaria caused by plasmodium falciparum. this is the severest form of malaria and is associated with the highest levels of parasites in the blood. this disease is characterized by irregularly recurring febrile paroxysms that in extreme cases occur with acute cerebral, renal, or gastrointestinal manifestations.

Patient EducationClinical

Malaria

Malaria is a serious disease caused by a parasite. You get it when an infected mosquito bites you. Malaria is a major cause of death worldwide, but it is almost wiped out in the United States. The disease is mostly a problem in developing countries with warm climates. If you travel to these countries, you are at risk.

Read the full article at MedlinePlus

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

Convert B50.9 to ICD-9-CMHistory

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

ICD-9-CM
084.0 Falciparum malaria
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About B50.9Overview

What is the ICD-10 code for plasmodium falciparum malaria, unspecified?

The ICD-10-CM code for plasmodium falciparum malaria, unspecified is B50.9 (sometimes written as B509). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is B50.9 (Plasmodium falciparum malaria) a billable code?

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

What MS-DRG does B50.9 group to?

When plasmodium falciparum malaria, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.

Is B50.9 a CC or MCC?

CMS lists B50.9 as an MCC (major complication or comorbidity) for FY 2027. 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 32 closely related codes in its exclusion list.

Can B50.9 be reported with a code from A06?

Not as a rule. The Excludes1 note at block B50-B64, which applies to B50.9, lists "amebiasis (A06.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).