Practice Management

ICD 10 Codes for Infectious and Parasitic Diseases: Range (A00-B99)

ICD 10 Codes for Infectious and Parasitic Diseases: Range (A00-B99)

11 Jan 2022
8 min
ICD 10 Code A00-B99: Infectious and Parasitic Diseases

The ICD-10-CM A00-B99 encompasses diverse medical codes for "certain infectious and parasitic diseases." These codes cover a spectrum of illnesses caused by infectious agents such as bacteria, viruses, fungi, protozoa, and parasites. 

We've grouped the codes into two main categories: Infectious Diseases and Parasitic Diseases. Learn about the key diagnosis under each range. 

ICD-10-CM Code A00-A79: Infectious Diseases 

Infectious Diseases (A00-A79) encompass a broad category of illnesses caused by microorganisms, including bacteria, viruses, protozoa, and parasites. These diseases are typically transmitted from one person to another, from animals to humans, or through contaminated food and water.

Infectious diseases can vary widely in severity, ranging from common illnesses like the flu to life-threatening conditions such as tuberculosis and HIV/AIDS. There are different categories under infectious diseases.

1. Bacterial Infections (ICD Code: Range A00-A49)

As the name suggests, bacterial infections cover diseases caused by bacteria. These infections can affect various body systems and organs.

Key ICD-10-CM Codes for Bacterial Infections
ICD Code Description Diagnosis
ICD Code A00 Cholera An acute diarrheal disease caused by the Bacterium Vibrio Cholerae, leading to severe dehydration
ICD Code A01 Typhoid and Paratyphoid Fevers Infections caused by the bacteria Salmonella Typhi (typhoid fever) and Salmonella Paratyphi (paratyphoid fever), characterized by fever and gastrointestinal symptoms
ICD Code A02 Other Salmonella Infections Infections caused by various Salmonella species, often resulting in gastroenteritis
ICD Code A03 Shigellosis An infectious disease caused by Shigella bacteria, leading to diarrhea, abdominal cramps, and fever
ICD Code A04 Other Bacterial Intestinal Infections Infections of the intestines caused by various other bacterial pathogens not classified elsewhere
ICD Code A05 Other Bacterial Foodborne Intoxications Food poisoning caused by bacterial toxins, such as Staphylococcus aureus or Bacillus cereus
ICD Code A06 Amebiasis An intestinal infection caused by the protozoan parasite Entamoeba Histolytica, leading to gastrointestinal symptoms
ICD Code A07 Other Protozoal Intestinal Diseases Infections of the intestinal tract caused by various other protozoa not classified elsewhere
ICD Code A08 Viral and Other Specified Intestinal Infections Various intestinal infections, including some of viral origin and other specified causes
ICD Code A09 Diarrhea and Gastroenteritis of Infectious Origin Diarrheal illnesses caused by infectious agents, including bacteria and viruses, often leading to gastrointestinal symptoms

Further Reading:

2. Viral Infections (A80-B34)

This range refers to diagnoses caused by viruses ranging from the common cold to more severe diseases like HIV/AIDS.

Viral diseases class may also cover Chronic viral hepatitis C diagnosis, a long-term viral infection of the liver caused by the hepatitis C virus (HCV), with its ICD Code being B18.2.

​ ​
Key ICD-10-CM Codes for Viral Infections
ICD Code Description Diagnosis
ICD Code A80 Acute Poliomyelitis An infectious viral disease caused by poliovirus, leading to muscle weakness and paralysis
ICD Code A81 Atypical Virus Infections of Central Nervous System Uncommon viral infections affecting the central nervous system, including viral encephalitis and related conditions
ICD Code A82 Rabies A deadly viral infection transmitted through the bite of infected animals, leading to neurological symptoms and death if untreated
ICD Code A83 Mosquito-Borne Viral Encephalitis Encephalitis (inflammation of the brain) caused by viruses transmitted by mosquitoes, such as West Nile virus or Japanese encephalitis virus
ICD Code A84 Tick-Borne Viral Encephalitis Encephalitis caused by viruses transmitted by ticks, including tick-borne encephalitis virus
ICD Code A85-A89 Viral Hemorrhagic Fevers A group of severe viral infections characterized by fever, bleeding tendencies, and organ failure, including diseases like Ebola and Lassa fever
ICD Code A92 Other Mosquito-Borne Viral Fevers Viral fevers transmitted by mosquitoes, excluding encephalitis, such as dengue fever or Zika virus infection
ICD Code A94 Other Arthropod-Borne Viral Fevers Viral fevers transmitted by arthropods (insects and arachnids), including diseases like yellow fever
ICD Code B05 Measles A highly contagious viral infection characterized by fever, cough, and a distinctive rash
ICD Code B26 Mumps An infectious disease caused by the mumps virus, leading to swelling of the salivary glands and other symptoms

3. Protozoal and Helminthic Infections (A50-B64)

These are infections caused by protozoa (single-celled organisms) and helminths (parasitic worms) and can lead to diseases like Malaria and Tapeworm infections.

This ICD Code cluster may also cover fungal infection. For instance, Onychomycosis' ICD 10 code is B35.1. Onychomycosis is a fungal infection of the nails, specifically the toenails or fingernails.

​ ​
Key ICD-10-CM Codes for Helminthic Infections
ICD Code Description Diagnosis
ICD Code A50 Congenital Syphilis Syphilis infection transmitted from mother to child during pregnancy or childbirth
ICD Code A51 Early Syphilis Initial stage of syphilis infection with primary, secondary, or early latent syphilis
ICD Code A52 Late Syphilis Late-stage syphilis infection, including tertiary syphilis with organ damage
ICD Code A53 Other and Unspecified Syphilis Various forms of syphilis that are not classified elsewhere, including unspecified syphilis.
ICD Code A54 Gonococcal Infection Infection caused by the bacterium Neisseria gonorrhoeae, commonly known as gonorrhea
ICD Code A59 Trichomoniasis Infection caused by the protozoan
ICD Code B50 Plasmodium falciparum Malaria A severe form of malaria caused by the protozoan parasite Plasmodium falciparum, leading to high fever and organ dysfunction
ICD Code B51 Plasmodium Vivax Malaria Malaria caused by the protozoan parasite Plasmodium Vivax, characterized by recurrent fever episodes
ICD Code B52 Plasmodium Malariae Malaria Malaria caused by the protozoan parasite Plasmodium Malariae, leading to a milder form of the disease
ICD Code B53 Other Malaria Malaria caused by various other Plasmodium species not classified elsewhere.

ICD-10-CM Code B65-B83: Parasitic Diseases 

The second classification under the ICD 10 Range (A00-B99) is the Parasitic Diseases. It covers the code range B65-B83, referring to illnesses caused by various parasitic organisms, including helminths (worms) and protozoa.

These diseases are characterized by their transmission from one host to another, often involving intermediate hosts like insects or snails. Parasitic diseases manifest in diverse ways, affecting different body systems, and may demonstrate varied symptoms and complications. The severity of these diseases can vary from mild discomfort to life-threatening conditions.

1. Helminthiases (B65-B83)

Helminthic infections are diseases brought by parasitic worms that result in diagnoses like Ascariasis and Trichuriasis.

​ ​
Key ICD-10-CM Codes for Helminthiasis Infections
ICD Code Description Diagnosis
ICD Code B65 Schistosomiasis (Bilharziasis) Infection caused by parasitic flatworms (schistosomes) found in freshwater, leading to many symptoms, including skin rash and organ damage.
ICD Code B68 Taeniasis Infection with tapeworms of the genus Taenia is often caused by eating undercooked pork or beef.
ICD Code B69 Cysticercosis Infection caused by the larval form of the pork tapeworm, resulting in cyst formation in various body tissues
ICD Code B70 Diphyllobothriasis and Sparganosis Infection with tapeworms of the genus Diphyllobothrium or the tissue parasite Spirometra, respectively
ICD Code B71 Other Cestode Infections Infections caused by various other tapeworm species not classified elsewhere
ICD Code B72 Dracunculiasis (Guinea-Worm Disease) Infection caused by the parasitic nematode Dracunculus Medinensis, leading to the development of painful skin ulcers
ICD Code B73 Onchocerciasis Infection with the filarial worm Onchocerca volvulus, often transmitted by blackflies, leading to skin and eye problems
ICD Code B74 Filariasis Infection with various filarial worms transmitted by mosquitoes, causing lymphatic or subcutaneous filariasis
ICD Code B76 Hookworm Diseases Infections caused by hookworms that lead to gastrointestinal and skin symptoms
ICD Code B79 Trichuriasis Infection caused by the whipworm Trichuris trichiura, primarily affecting the large intestine

Further Reading:


ICD-10-CM codes within the range A00-B99 are essential for accurately diagnosing, treating, billing, and researching infectious and parasitic diseases. Proper documentation is crucial for effective coding. These codes contribute to the overall healthcare system by facilitating disease management, resource allocation, and epidemiological surveillance.

Disclaimer: The information provided in this blog regarding the International Classification of Diseases (ICD) codes is intended for informational purposes only. We strive to offer accurate and up-to-date content. However, the ICD codes are subject to changes, updates, and modifications by authoritative bodies such as the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and other relevant healthcare organizations. These changes can occur due to advancements in medical knowledge, new diseases, evolving diagnostic criteria, or updates in medical terminology.


  1. What is ICD-10-CM, and why is it important for infectious diseases?
    ICD-10-CM A00-B99 is a coding system that classifies infectious diseases for diagnosis, billing, and research purposes. It's crucial for tracking and managing infections effectively.
  2. How can healthcare professionals use ICD-10-CM codes effectively?
    Healthcare professionals should accurately document diseases, specifying type, site, and complications, to use ICD-10-CM codes effectively.
  3. What are the primary differences between viral, bacterial, and parasitic infections in coding?
    Differences include the type of microorganism (virus, bacteria, parasite), specific codes, and the need for detailed documentation.
  4. Are there any recent updates or changes in the ICD-10-CM codes for infectious diseases?
    For updates, healthcare professionals should refer to resources such as the Centers for Disease Control and Prevention (CDC) and relevant coding guidelines.

Need some help? Talk to an Expert

Up the Ante with Upvio

Link copied