2027 ICD-10-CM Diagnosis Code B51.9Plasmodium vivax malaria without complication
ICD-10-CM Codes›A00–B99›B50-B64›B51
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
B51.9 is a billable ICD-10-CM diagnosis code for plasmodium vivax malaria without complication. 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 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 49 closely related codes. Coders also document this condition as intermittent fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Intermittent fever
- Malarial fever
- Tertian fever
- Vivax malaria
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B51.9: its own notes plus those printed at B51, 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.
- mixed infections of Plasmodium vivax with other Plasmodium species, except Plasmodium falciparum
- 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.
- Plasmodium vivax malaria NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- plasmodium vivax with Plasmodium falciparum (B50.-)
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.
- 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.
- 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 B51.9, its category, or a range that includes it.
Applicable To 1
These notes mention B51.9.
- O98.6 Protozoal diseases complicating pregnancy, childbirth and the puerperium
Excludes1 3
These codes carry an Excludes1 note naming B51.9: they are not reported together with it, unless the two conditions are unrelated.
- B52 Plasmodium malariae malariaPlasmodium vivax (B51.-) names B51.-, which includes this code
- B53.0 Plasmodium ovale malariaPlasmodium ovale with Plasmodium vivax (B51.-) names B51.-, which includes this code
- B53.1 Malaria due to simian plasmodiaMalaria due to simian plasmodia with Plasmodium vivax (B51.-) names B51.-, which includes this code
Code First 2
These codes say to code first a condition named in the note, and B51.9 is one of the conditions named.
Index to Diseases and InjuriesGuidance
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Malaria, Vivax
malaria caused by plasmodium vivax. this form of malaria is less severe than malaria, falciparum, but there is a higher probability for relapses to occur. febrile paroxysms often occur every other day.
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 B51.9 to ICD-9-CMHistory
Code HistoryHistory
Questions About B51.9Overview
What is the ICD-10 code for plasmodium vivax malaria without complication?
The ICD-10-CM code for plasmodium vivax malaria without complication is B51.9 (sometimes written as B519). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B51.9 (Plasmodium vivax malaria) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report plasmodium vivax malaria without complication on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B51.9 group to?
When plasmodium vivax malaria without complication 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 B51.9 a CC or MCC?
CMS lists B51.9 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 49 closely related codes in its exclusion list.
Can B51.9 be reported with a code from B50?
Not as a rule. The Excludes1 note at B51, which applies to B51.9, lists "plasmodium vivax with Plasmodium falciparum (B50.-)". 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).
