July 17, 2012

Exploring ICD-10-CM Chapter 1: Certain Infectious & Parasitic Disease

By

In a previous article titled ICD-10: the Axis of Classification, we had indicated that one method for preparing your key stakeholders for the transition to ICD-10 is to break ICD-10-CM down into its basic components: chapters and axes of classification. This article will continue that theme in reviewing changes we will encounter in ICD-10-CM Chapter 1, “Certain Infectious & Parasitic Disease.”

In the 2012 fiscal-year version of ICD-9-CM, the code range for Chapter 1 is 001-139 and consists of 1,270 codes. Compare this to the FY 2012 version of ICD-10-CM, in which Chapter 1’s code range is A00-B99 and consists of 1,056 codes. This comparison nets us a decrease of 214 codes, or a decline of 17 percent. This is the only chapter in ICD-10-CM that contains fewer codes than the corresponding chapter in ICD-9-CM, but don’t let the decrease in volume of codes fool you – the complexity of information reported by the codes in this chapter has increased, as compared to ICD-9-CM.

We start by noting that there are 21 chapter blocks in ICD-10-CM’s Chapter 1. A review of the chapter block titles provides a glimpse into how this chapter is organized.

Chapter 1 Chapter Blocks

A00-A09 Intestinal infectious diseases
A15-A19 Tuberculosis
A20-A28 Certain zoonotic bacterial diseases
A30-A49 Other bacterial diseases
A50-A64 Infections with a predominantly sexual mode of transmission
A65-A69 Other spirochetal diseases
A70-A74 Other diseases caused by chlamydiae
A75-A79 Rickettsioses
A80-A89 Viral infections of the central nervous system
A90-A99 Arthropod-borne viral fevers and viral hemorrhagic fevers

B00-B09 Viral infections characterized by skin and mucous membrane lesions
B15-B19 Viral hepatitis
B20-B24 Human immunodeficiency virus (HIV) disease
B25-B34 Other viral diseases
B35-B49 Mycoses
B50-B64 Protozoal diseases
B65-B83 Helminthiases
B85-B89 Pediculosis, acariasis and other infestations
B90-B94 Sequelae of infectious and parasitic diseases
B95-B97 Bacterial, viral and other infectious agents
B99         Other infectious diseases

In general, the changes you will note when reviewing Chapter 1 are:

  • Many codes have been added, deleted, combined, expanded or moved, either to a different section of this chapter or to another chapter entirely. This is a common finding across many of the ICD-10-CM chapters.
  • Expansion in the axis of classification for this chapter often reports the specific type/etiology of a condition and/or its manifestation. This results in one of the more challenging aspects of coding diagnoses in Chapter 1 — obtaining documentation that identifies and clearly links etiology and manifestation. This level of detail in the documentation allows for reporting a combination code, where applicable, as opposed to coding both conditions separately.

In exploring Chapter 1 in greater detail you will note the following:

  • Sepsis, although still reported by etiology, is now split into two categories, A40 & A41, denoting “streptococcal” and “other,” respectively. Both codes report the specific organism involved at the fourth digit. If the causative organism is unknown, one can assign the unspecified code A41.9, “septicemia, NOS” (meaning sepsis). This is ICD-10-CM’s corresponding code for ICD-9-CM’s 038.9, “unspecified septicemia.”
  • SIRS is coded R65.10, without organ dysfunction or R65.11, with organ dysfunction. Both of these codes are classified to Chapter 18, Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (R00-R99), along with “Bacteremia,” which is coded to R78.81.
  • Intestinal infections now are split into three sections classified by type of infection. For example, infectious gastroenteritis is classified by specific causative organism (such as viral, bacterial, fungal or parasitic/amebic), but options for “other” and “unspecified” are also available for selection.
  • Tuberculosis has been restructured and consolidated, and is reported based on anatomical site or type. Examples include respiratory tuberculosis, tuberculosis of the nervous system or other organs, miliary tuberculosis (otherwise known as "disseminated tuberculosis,“ "tuberculosis cutis acuta generalisata," or "tuberculosis cutis disseminate”).
  • Hepatitis codes now reflect etiology, acuity and severity, classifications that also indicate the absence or presence of hepatitis delta. The term “delta agent” refers to a type of virus called hepatitis D that causes symptoms only in people who also have a hepatitis B infection. This concomitant infection was not reportable using ICD-9-CM.
  • There were also numerous changes to conditions rarely seen in the U.S. and conditions typically treated in the outpatient setting.

These are just some of the examples of changes one can anticipate when reporting Certain Infectious & Parasitic Disease utilizing ICD-10-CM.

About the Author

Angela Carmichael, MBA, RHIA, CCS, CCS-P, is director of HIM compliance for J.A. Thomas & Associates. Angela earned a Bachelor of Science degree, in Health Services Administration from Barry University and a MBA from Nova Southeastern University. She is a Registered Health Information Administrator and also has achieved the designations of Certified Coding Specialist, and Certified Coding Specialist-Physician and AHIMA Approved ICD-10-CM/PCS Instructor.

Contact the Author

To comment on this article please go to

Angela Carmichael