Question 1

What is ICD-10 code B51.9?

Accepted Answer

B51.9 is the ICD-10-CM diagnosis code for plasmodium vivax malaria without complication. A type of malaria caused by Plasmodium vivax parasite without serious complications. This is a parasitic infection transmitted through mosquito bites. B51.9 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering protozoal diseases (b50-b64).

B51.9 is a billable ICD-10-CM code, but the current payload does not show a mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.

Use this code only when malaria is confirmed as P. vivax type and no complications are documented.

Question 2

Is B51.9 an HCC code?

Accepted Answer

B51.9 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

Question 3

Is B51.9 billable?

Accepted Answer

Yes. B51.9 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. B51.9 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

Which HCC does B51.9 map to under V28?

Accepted Answer

B51.9 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

Question 5

What RAF reference is published for B51.9?

Accepted Answer

B51.9 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

Question 6

What is the V28 vs V24 difference for B51.9?

Accepted Answer

B51.9 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

Question 7

What documentation supports B51.9?

Accepted Answer

Use this code only when malaria is confirmed as P. vivax type and no complications are documented If complications like cerebral malaria or severe anemia are present, use a more specific code from the B51 category B51.9 is not a CMS-HCC V28 payment code in the verified current source, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

Question 8

Can B51.9 be a primary diagnosis?

Accepted Answer

Yes. B51.9 carries no code-first instruction in the FY2026 tabular, so it can be the first-listed diagnosis when it is the condition chiefly responsible for the encounter and the note supports it, and it can also be reported as a secondary diagnosis. For risk adjustment the order does not matter; the V28 category is the same either way.

Question 9

Which codes cannot be reported with B51.9?

Accepted Answer

The Excludes1 note that applies to B51.9 lists certain localized infections - see body system-related chapters; amebiasis (A06.-); other protozoal intestinal diseases (A07.-); plasmodium vivax with Plasmodium falciparum (B50.-). An Excludes1 condition is not reported together with B51.9; report one or the other, unless the two conditions are unrelated, which the ICD-10-CM Official Guidelines (Section I.A.12.a) allow. The Excludes2 note lists carrier or suspected carrier of infectious disease (Z22.-); 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); those are separate conditions that may be reported together with B51.9 when both are documented.

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B51.9

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B51.9 ICD-10-CM Code: Plasmodium vivax malaria without complication

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B51.9

Is B51.9 an HCC code?

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What This Code Means

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Work B51.9 in HCC Buddy