ICD-10 code B75: Trichinellosis diagnosis and billing guide

Key Takeaways

ICD-10 code B75 is a fully billable ICD-10-CM diagnosis code for Trichinellosis, classified under Chapter I, Helminthiases (B65-B83).

B75 includes infection due to Trichinella species and trichiniasis; it has no child subcodes, making it the sole code for this condition.

Accurate documentation must identify the Trichinella species exposure source, presenting symptoms (myositis, eosinophilia, periorbital edema), and any organ manifestations that require additional codes.

Pabau’s claims management software and digital forms streamline ICD-10 documentation workflows, reducing claim errors for infectious disease encounters.

ICD-10 code B75: Definition and clinical description of Trichinellosis

ICD-10 code B75 is the designated billable code for Trichinellosis, a parasitic infection caused by Trichinella species nematodes. According to the WHO’s ICD-10 browser, B75 sits within Chapter I (Certain Infectious and Parasitic Diseases) under the Helminthiases block (B65-B83), which covers roundworm, flatworm, and related parasitic worm infections. This reference covers the code’s billable status, official includes notes, synonyms, related codes, and the documentation requirements coders need to submit clean claims.

Trichinellosis is an uncommon but clinically significant zoonotic infection. Humans contract it by consuming raw or undercooked meat containing Trichinella larvae, most commonly pork, wild boar, or game meat. The larvae migrate into skeletal muscle tissue after intestinal invasion, producing a characteristic cluster of symptoms: periorbital edema, myalgia, fever, and peripheral eosinophilia. Accurate ICD-10 diagnostic coding for infectious presentations like this one depends on understanding both the code’s official classification and the clinical context that triggers documentation requirements.

Billable status and code structure for ICD-10 code B75

B75 is a fully billable ICD-10-CM diagnosis code. It can be used directly on insurance claims, hospital discharge records, and outpatient encounter forms without requiring a more specific subcode. Per the CDC/NCHS ICD-10-CM web tool, B75 carries no child codes. It represents the only code in the B75 subcategory, meaning there is no further specificity available within the official classification system for this condition.

The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS) jointly maintain ICD-10-CM under authority from the CMS ICD-10 codes page, which publishes annual updates to the code set.

B75 has remained stable in its classification and description across fiscal year updates through FY2026. Coders can confirm current-year validity using official CMS release files.

Includes notes, synonyms, and alternate terms for B75

Understanding the official includes notes prevents undercoding. The ICD-10-CM tabular list specifies two items within B75’s includes notation.

• Infection due to Trichinella species – covers all species within the Trichinella genus, including T. spiralis (the most common human pathogen), T. britovi, T. nativa, and T. pseudospiralis
• Trichiniasis – the older clinical term for the same disease process, used interchangeably in some legacy documentation

Beyond the official includes, several synonyms appear in coding reference databases and clinical records. Coders encountering any of these terms in physician documentation should map them to B75.

• Diaphragmatic trichiniasis
• Diaphragmitis (when caused by Trichinella)
• Disease caused by Trichinelloidea
• Infection by Trichinella spiralis
• Muscle infection due to Trichinella larvae
• Trichinella myositis

Coders working from dictated or transcribed notes may encounter “trichiniasis” and “trichinellosis” used interchangeably. Both map to B75. If documentation only specifies “parasitic myositis” without naming the organism, do not assign B75 without clinical confirmation. Use the correct ICD-10 code documentation workflow: confirm the causative organism in the clinical notes before assigning the code.

ICD-10 code B75 coding notes and sequencing guidelines

Trichinellosis frequently presents with multi-system manifestations. B75 has no “use additional code” or “code first” note in the tabular list and is not part of an etiology/manifestation code pair. As a general sequencing principle, when a manifestation is present alongside the underlying parasitic infection and the infection is the reason for the encounter, sequence B75 first and add codes for the documented manifestations.

When to use additional codes with B75

Several manifestations of Trichinellosis require separate codes to fully capture the clinical picture. Standard coding practice is to add a code for each manifestation that is documented as a distinct clinical problem.

• Myositis (M60.09 or site-specific myositis codes) – when muscle inflammation is documented as a separate clinical concern
• Eosinophilia (D72.1) – when laboratory-confirmed eosinophilia is listed as a clinical finding in the encounter
• Encephalitis or central nervous system involvement – use appropriate G-code for the manifestation when neurological symptoms are documented
• Myocarditis (I51.4) – Trichinella-related cardiac muscle involvement warrants additional coding when clinically confirmed

Sequencing rules: Principal vs. Secondary diagnosis

When trichinellosis is the primary reason for the encounter, sequence B75 first. If the patient presents for a manifestation (such as myocarditis) and trichinellosis is identified as the underlying cause, sequencing depends on whether the manifestation has a mandatory “code first” instruction. Review the specific manifestation code in the tabular list for any instructional notes before finalizing sequence order.

For inpatient settings, the Uniform Hospital Discharge Data Set (UHDDS) definition of principal diagnosis applies: the condition established after study to be chiefly responsible for the admission. If the patient was admitted for acute myositis with Trichinella later confirmed as the cause, the attending physician’s documented reason for admission guides principal diagnosis selection. Coders using claims management software can flag these multi-code encounters for review to prevent sequencing errors before submission.

Related codes in the B65-B83 Helminthiases block

B75 sits within the Helminthiases block alongside a range of other parasitic worm infections. Knowing adjacent codes prevents confusion when documentation lacks organism specificity.

The clinical distinction between Trichinellosis and similar nematode infections matters for coding accuracy. B76 (hookworm diseases) and B77 (ascariasis) both involve intestinal nematodes, but they do not produce the larval muscle migration characteristic of Trichinella.

When physician documentation identifies eosinophilia and periorbital edema following consumption of undercooked meat, the clinical picture strongly supports B75 over B89. Using B89 (unspecified parasitic disease) when B75 is clinically confirmed is an undercoding error. Good parasitic infection ICD-10 coding practice requires selecting the most specific code supported by the documentation.

ICD-9-CM to ICD-10-CM crosswalk for Trichinellosis

Practices transitioning legacy records or reviewing historical claims will encounter ICD-9-CM codes. The direct predecessor to B75 is ICD-9-CM code 124 (Trichinosis). The crosswalk is straightforward: 124 maps to B75 with a one-to-one equivalency for both general trichinellosis presentations.

The terminology shift from “trichinosis” (ICD-9 convention) to “trichinellosis” (ICD-10 convention) reflects updated WHO nomenclature that aligns with the organism’s genus name, Trichinella. Both terms describe the same clinical condition. For payers still processing historical claims under ICD-9-CM, the crosswalk above confirms equivalency. Coders can also verify this mapping using the AAPC Codify ICD-10-CM lookup tool.

Struggling with multi-code infectious disease encounters?

Pabau's claims management and digital documentation tools help practices build coding checklists, flag manifestation codes, and submit cleaner claims for complex diagnoses like Trichinellosis.

Book a demo

Documentation requirements for billing ICD-10 code B75

Clean claims for B75 require specific documentation elements. Missing any of these increases the risk of medical necessity denials or post-payment audits.

• Exposure history – documented consumption of raw or undercooked meat (pork, wild boar, horse, walrus, or game) within the preceding weeks
• Clinical presentation – at minimum two of the classic triad: periorbital edema, myalgia or myositis, and fever; eosinophilia on CBC is a supporting finding
• Laboratory confirmation – positive serology (enzyme-linked immunosorbent assay or indirect immunofluorescence for Trichinella antibodies) and/or positive muscle biopsy identifying encysted larvae
• Organism specification – documentation stating “Trichinella species,” “T. spiralis,” or “trichinellosis” by name. “Parasitic infection, unspecified” is insufficient to assign B75
• Manifestation documentation – any organ-specific complications (myocarditis, encephalitis, myositis) must be separately documented to justify additional codes

Structured digital intake forms that capture exposure history and travel background improve documentation completeness at the point of intake. For infectious disease encounters, pre-built intake templates that prompt clinicians for organism exposure, symptom onset timeline, and laboratory results reduce the documentation gaps that generate denials.

Pabau’s digital forms can be configured to collect this data before the encounter, giving coders what they need from the outset. Practices managing compliance requirements across complex case types also benefit from compliance documentation workflows that track documentation completeness per encounter.

Excludes notes and coding restrictions

The ICD-10-CM tabular list does not contain a Type 1 (Excludes 1) note for B75 that would prohibit simultaneous coding with related codes. This means coders can legitimately assign B75 alongside manifestation codes (eosinophilia, myositis, myocarditis) when each is independently documented. Always check the most current CMS tabular list for any additions to excludes notes in annual updates. Maintaining access to updated medical documentation forms and coding checklists ensures that annual ICD-10-CM changes are captured in practice workflows without requiring manual review of each code.

Epidemiology and clinical context relevant to coding B75

Coding accuracy benefits from clinical context. Trichinellosis is a zoonotic nematode infection with a global but uneven distribution. According to the WHO’s ICD-10 classification framework, Trichinella species infections fall within the broader helminthiases category precisely because the organism’s life cycle involves a definitive mammalian host and a tissue-invasive larval stage, distinguishing it from simple intestinal roundworm infections.

In the United States, the CDC tracks Trichinellosis cases as a notifiable condition. Case counts are historically low (fewer than 20 confirmed U.S. cases per year in recent decades), but clusters occur when contaminated game meat is shared at communal meals.

Clinicians at functional medicine and integrative health practices that work with patients who hunt or consume non-commercial game are the most likely to encounter this diagnosis. International travel to regions with higher prevalence (parts of Eastern Europe, Southeast Asia, and the Arctic) also elevates clinical suspicion.

The clinical phase of infection determines what codes accompany B75. During the intestinal phase (days 1-7 post-ingestion), gastrointestinal symptoms predominate. The muscle invasion phase (weeks 2-8) produces the classic periorbital edema, myalgia, and eosinophilia. Severe infections involve cardiac and neurological complications.

Documenting the phase and any organ involvement determines whether additional codes are warranted alongside B75. Clinicians who rely on structured patient record documentation capture this timeline detail systematically, giving coders the clinical narrative needed to assign B75 and any manifestation codes accurately.

Conclusion

Trichinellosis is a rare but clinically specific diagnosis that requires precise ICD-10 documentation. Most claims issues with B75 trace back to incomplete exposure history, missing manifestation codes, or the use of unspecified parasitic codes when B75 is clearly supported by the clinical record.

Pabau’s automated clinical workflows and digital forms let practices build encounter templates that capture exposure history, organism confirmation, and manifestation documentation at the point of care, so coding teams have the clinical context they need from the first note. To see how Pabau supports infectious disease documentation and claims accuracy, book a demo with the team.

Continue your research

Need a structured framework for clinical documentation compliance? Compliance management software covers how Pabau helps practices track documentation completeness and reduce audit exposure.

Looking to streamline multi-code encounter submissions? Practice management software explains how integrated billing workflows reduce claim errors across complex diagnoses.

Want pre-built intake forms for infectious disease encounters? Digital forms shows how Pabau’s configurable templates capture exposure history and clinical findings before the encounter begins.

Frequently Asked Questions