Certain infectious and parasitic diseases
This chapter covers diseases caused by infectious agents such as bacteria, viruses, fungi, and parasites. These conditions are contagious (though not always) and result from invasion of the body by microorganisms. It includes everything from common infections like influenza and tuberculosis to HIV, malaria, and COVID-19. The codes are organized by type of pathogen and body system affected.
It also includes systemic infections (sepsis), sexually transmitted infections, and vector-borne diseases (like dengue or Lyme disease). Parasitic infections such as helminths and protozoa fall here too. Some chronic infections, like hepatitis B and C, are included because they persist over time.
This chapter is heavily used in public health reporting and epidemiology because infectious diseases can spread through populations. Accurate coding helps track outbreaks, monitor disease trends, and allocate healthcare resources. Many codes also specify drug resistance, complications, or disease stage.
In short, this chapter captures diseases where an infectious organism is the root cause, whether acute, chronic, localized, or systemic.
Clinical & Coding Guidelines
Includes
- diseases generally recognized as communicable or transmissible
Excludes1 (Strict rejection)
- certain localized infections - see body system-related chapters
Excludes2 (Partial exclusion)
- 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)