A66.0

Initial lesions of yaws

FY2027Chapter 1: Certain infectious and parasitic diseases/A65–A69 Other spirochetal diseases

BillableComplete code, valid to report

A66.0 (also written A660) is a billable ICD-10-CM diagnosis code for initial lesions of yaws. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 10 codes in category A66 (Yaws). The Alphabetic Index lists it under 10 entries. Its coding notes include a Use additional code instruction and 7 Excludes2 entries.

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (1 note)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • code to identify resistance to antimicrobial drugs (Z16.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (7 notes)
Inherited from A65–A69 Other spirochetal diseases
  • leptospirosis (A27.-)
  • syphilis (A50-A53)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • 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)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Infectious Disease, Neoplasms, and Blood-Forming Diseases clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Includes

Further defines or gives examples of the content of the category.

Inherited from A66 Yaws
  • bouba
  • frambesia (tropica)
  • pian
Also from chapter/block level (1 note)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • diseases generally recognized as communicable or transmissible

Inclusion terms

Conditions classified to this code.

This code
  • Chancre of yaws
  • Frambesia, initial or primary
  • Initial frambesial ulcer
  • Mother yaw

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 10 entries