2027 ICD-10-CM Diagnosis Code Z20.818Contact with and (suspected) exposure to other bacterial communicable diseases

ICD-10-CM Codes›Z00–Z99›Z20-Z29›suspected

ICD-10-CM Z20.818
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z20.818 is a billable ICD-10-CM diagnosis code for contact with and (suspected) exposure to other bacterial communicable diseases. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 795, 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Exposure, encounters, screening or contact with infectious disease.

Code Identity

ICD-10-CM Code
Z20.818
Billable Status
Yes — Valid for Submission
Code Describes
Contact with and (suspected) exposure to other bacterial communicable diseases
Short Description
Contact w and exposure to oth bact communicable diseases
Parent Code
Z20.81
Contact with and (suspected) exposure to other bacterial communicable diseases

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ20-Z29Persons with potential health hazards related to communicable diseases
CategorysuspectedContact with and exposure to communicable diseases (Z20)
This CodeZ20.818Contact with and (suspected) exposure to other bacterial communicable diseases

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z20.818.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Brucellosis suspected
  • Diphtheria suspected
  • Exposure to acquired carbapenemase-producing bacteria
  • Exposure to anaerobic bacterial vaginosis
  • Exposure to bacterial vaginosis
  • Exposure to Bordetella pertussis
  • Exposure to Coccidioides immitis
  • Exposure to Francisella tularensis
  • Exposure to Gardnerella vaginalis
  • Exposure to Haemophilus ducreyi
  • Exposure to Haemophilus influenzae type b
  • Exposure to Klebsiella granulomatis
  • Exposure to Legionella
  • Exposure to Listeria moncytogenes
  • Exposure to Salmonella
  • Exposure to streptococcal pharyngitis
  • Exposure to Streptococcus
  • Exposure to Streptococcus pneumoniae
  • Exposure to Vibrio cholerae
  • Invasive group A beta-hemolytic streptococcal disease suspected
  • Legionella pneumonia suspected
  • Leprosy suspected
  • Lyme disease suspected
  • Pertussis suspected
  • Plague suspected
  • Scarlet fever suspected
  • Suspected bacterial infection
  • Suspected soft tissue infection
  • Tetanus suspected
  • Typhoid fever suspected
  • Typhus suspected

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z20.818: its own notes plus those printed at Z20 and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Excludes1

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

From Z20 Contact with and (suspected) exposure to communicable diseases applies to 18 codes
  • carrier of infectious disease (Z22.-)
  • diagnosed current infectious or parasitic disease -see Alphabetic Index

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 Z20 Contact with and (suspected) exposure to communicable diseases applies to 18 codes
  • personal history of infectious and parasitic diseases (Z86.1-)

Notes

General instructions on how these codes are used.

From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z20.818, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming Z20.818: its condition is not part of those codes, and both may be reported when the patient has both.

  • Z77 Other contact with and (suspected) exposures hazardous to health
    contact with and (suspected) exposure to communicable diseases (Z20.-) names Z20.-, which includes this code
  • Z83 Family history of other specific disorders
    contact with and (suspected) exposure to communicable disease in the family (Z20.-) names Z20.-, 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 FAC016
Exposure, encounters, screening or contact with infectious disease
Default principal diagnosis: inpatient No · outpatient Yes

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

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

Convert Z20.818 to ICD-9-CMHistory

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

ICD-9-CM
V01.89 Communic dis contact NEC
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 Z20.818Overview

Is Z20.818 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report contact with and (suspected) exposure to other bacterial communicable diseases on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z20.818 group to?

On inpatient claims, contact with and (suspected) exposure to other bacterial communicable diseases maps to MS-DRG 951, 795, with relative weights from 0.2022 to 0.5574 depending on complications. Higher weights mean higher Medicare reimbursement.

Can Z20.818 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because contact with and (suspected) exposure to other bacterial communicable diseases describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Can Z20.818 be reported with a code from Z22?

Not as a rule. The Excludes1 note at Z20, which applies to Z20.818, lists "carrier of infectious disease (Z22.-)". 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).

What is the ICD-9 equivalent of Z20.818?

Under the General Equivalence Mappings, contact with and (suspected) exposure to other bacterial communicable diseases converts to ICD-9-CM V01.89 (communic dis contact NEC). The mapping is approximate, so confirm the match fits the documentation.