ICD-10 Code for Infection
Also indexed as (opportunistic)
The ICD-10-CM code for infection is B99.9 — Unspecified infectious disease. This is the code the Alphabetic Index gives for infection with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).
BillableUnspecified
B99.9 is billable but unspecified. If the documentation names a type, site or cause, one of the more specific codes below is likely expected.
Which infection code should you use?
The Alphabetic Index lists 484 codes under Infection, infected, infective. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.
By type
| Acanthocheilonema | B74.4 | Mansonelliasis | |
| Acinetobacter baumannii, as cause of disease classified elsewhere | B96.83 | Acinetobacter baumannii as the cause of diseases classified elsewhere | |
| Acremonium falciforme | B47.0 | Eumycetoma | |
| acromioclavicular | M00.9 | Pyogenic arthritis, unspecified | |
| Actinobacillus | A28.8 | Other specified zoonotic bacterial diseases, not elsewhere classified | |
| Actinomadura | B47.1 | Actinomycetoma | |
| Actinomyces | A42.9 | Actinomycosis, unspecified | |
| adenoid | J03.90 | Acute tonsillitis, unspecified | |
| aerogenes capsulatus | A48.0 | Gas gangrene | |
| Allescheria boydii | B48.2 | Allescheriasis | |
| Alternaria | B48.8 | Other specified mycoses | |
| alveolus, alveolar | K04.7 | Periapical abscess without sinus | |
| amniotic fluid, sac or cavity | O41.10 | Infection of amniotic sac and membranes, unspecified | not billable |
| Ancylostoma | B76.0 | Ancylostomiasis | |
| Anisakiasis, Anisakis larvae | B81.0 | Anisakiasis | |
| anus, anal | K62.89 | Other specified diseases of anus and rectum | |
| arbovirus | A94 | Unspecified arthropod-borne viral fever | |
| artificial insemination | N98.0 | Infection associated with artificial insemination | |
| Ascomycetes | B47.0 | Eumycetoma | |
| axillary gland | L04.2 | Acute lymphadenitis of upper limb | |
| Bacillus | A49.9 | Bacterial infection, unspecified | |
| bacterial NOS | A49.9 | Bacterial infection, unspecified | |
| Bacteroides NEC | A49.8 | Other bacterial infections of unspecified site | |
| Balantidium coli | A07.0 | Balantidiasis | |
| Bartholin's gland | N75.8 | Other diseases of Bartholin's gland | |
| Basidiobolus | B46.8 | Other zygomycoses | |
| Borrelia bergdorfi | A69.20 | Lyme disease, unspecified | |
| brain | G04.90 | Encephalitis and encephalomyelitis, unspecified | |
| branchial cyst | Q18.0 | Sinus, fistula and cyst of branchial cleft | |
| Brucella | A23.9 | Brucellosis, unspecified | |
| Brugia | B74.1 | Filariasis due to Brugia malayi | |
| buttocks | L08.9 | Local infection of the skin and subcutaneous tissue, unspecified | |
| Campylobacter, intestinal | A04.5 | Campylobacter enteritis | |
| candiru | B88.8 | Other specified infestations | |
| Capillaria | B81.1 | Intestinal capillariasis | |
| catheter-related bloodstream | T80.211 | Bloodstream infection due to central venous catheter | not billable |
| cat liver fluke | B66.0 | Opisthorchiasis | |
| central line-associated | T80.219 | Unspecified infection due to central venous catheter | not billable |
| Cephalosporium falciforme | B47.0 | Eumycetoma | |
| cervical gland | L04.0 | Acute lymphadenitis of face, head and neck | |
| cesarean delivery wound | O86.00 | Infection of obstetric surgical wound, unspecified | |
| chest | J22 | Unspecified acute lower respiratory infection | |
| Chilomastix | A07.8 | Other specified protozoal intestinal diseases | |
| Chlamydia, chlamydial | A74.9 | Chlamydial infection, unspecified | |
| Clonorchis | B66.1 | Clonorchiasis | |
| colostomy | K94.02 | Colostomy infection | |
| congenital | P39.9 | Infection specific to the perinatal period, unspecified | |
| Conidiobolus | B46.8 | Other zygomycoses | |
| coronavirus-2019 | U07.1 | COVID-19 | |
| coronavirus NEC | B34.2 | Coronavirus infection, unspecified | |
| cotia virus | B08.8 | Other specified viral infections characterized by skin and mucous membrane lesions | |
| COVID-19 | U07.1 | COVID-19 | |
| Coxiella burnetii | A78 | Q fever | |
| Cronobacter | A49.8 | Other bacterial infections of unspecified site | |
| Cryptosporidium | A07.2 | Cryptosporidiosis | |
| cystic duct | K81.9 | Cholecystitis, unspecified | |
| cytomegalovirus, cytomegaloviral | B25.9 | Cytomegaloviral disease, unspecified | |
| delta-agent, in hepatitis B carrier | B17.0 | Acute delta-(super) infection of hepatitis B carrier | |
| dental | K04.7 | Periapical abscess without sinus | |
| Deuteromycetes | B47.0 | Eumycetoma | |
| Dicrocoelium dendriticum | B66.2 | Dicroceliasis | |
| Dipetalonema | B74.4 | Mansonelliasis | |
| Diphyllobothrium | B70.0 | Diphyllobothriasis | |
| Diplogonoporus | B71.8 | Other specified cestode infections | |
| Dipylidium caninum | B67.4 | Echinococcus granulosus infection, unspecified | |
| Dirofilaria | B74.8 | Other filariases | |
| Dracunculus medinensis | B72 | Dracunculiasis | |
| Drechslera | B43.8 | Other forms of chromomycosis | |
| ducreyi Haemophilus | A57 | Chancroid | |
| during labor NEC | O75.3 | Other infection during labor | |
| Eberthella typhosa | A01.00 | Typhoid fever, unspecified | |
| endocardium | I33.0 | Acute and subacute infective endocarditis | |
| Enterobacter sakazakii | B96.89 | Other specified bacterial agents as the cause of diseases classified elsewhere | |
| Enterobius vermicularis | B80 | Enterobiasis | |
| enterostomy | K94.12 | Enterostomy infection | |
| enterovirus | B34.1 | Enterovirus infection, unspecified | |
| Entomophthora | B46.8 | Other zygomycoses | |
| episiotomy | O86.09 | Infection of obstetric surgical wound, other surgical site | |
| erythema infectiosum | B08.3 | Erythema infectiosum [fifth disease] | |
| Escherichiacoli NEC | A49.8 | Other bacterial infections of unspecified site | |
| Fasciola | B66.3 | Fascioliasis | |
| Fasciolopsis | B66.5 | Fasciolopsiasis | |
| finger | L08.9 | Local infection of the skin and subcutaneous tissue, unspecified | |
| fish tapeworm | B70.0 | Diphyllobothriasis | |
| flagellate, intestinal | A07.9 | Protozoal intestinal disease, unspecified | |
| Fonsecaea | B43.0 | Cutaneous chromomycosis | |
| foot | L08.9 | Local infection of the skin and subcutaneous tissue, unspecified | |
| fungus NOS | B49 | Unspecified mycosis | |
| Fusarium | B48.8 | Other specified mycoses | |
| generator pocket, implanted electronic neurostimulator | T85.734 | Infection and inflammatory reaction due to implanted electronic neurostimulator, generator | not billable |
| Ghon tubercle, primary | A15.7 | Primary respiratory tuberculosis | |
| Giardia lamblia | A07.1 | Giardiasis [lambliasis] | |
| gingiva | K05.10 | Chronic gingivitis, plaque induced | |
| glanders | A24.0 | Glanders | |
| glenosporopsis | B48.0 | Lobomycosis | |
| Gnathostoma | B83.1 | Gnathostomiasis | |
| Gongylonema | B83.8 | Other specified helminthiases | |
| gram-negative bacilli NOS | A49.9 | Bacterial infection, unspecified | |
| guinea worm | B72 | Dracunculiasis | |
| gum | K05.10 | Chronic gingivitis, plaque induced | |
| Helicobacter pylori | A04.8 | Other specified bacterial intestinal infections | |
| helminths | B83.9 | Helminthiasis, unspecified | |
| hipNEC | M00.9 | Pyogenic arthritis, unspecified | |
| Heterophyes | B66.8 | Other specified fluke infections | |
| hookworm | B76.9 | Hookworm disease, unspecified | |
| hydrocele | N43.0 | Encysted hydrocele | |
| Hymenolepis | B71.0 | Hymenolepiasis | |
| inguinalglands | L04.1 | Acute lymphadenitis of trunk | |
| intervertebral disc, pyogenic | M46.30 | Infection of intervertebral disc (pyogenic), site unspecified | |
| intra-amniotic affecting newborn NEC | P39.2 | Intra-amniotic infection affecting newborn, not elsewhere classified | |
| intrauterine inflammation | O41.12 | Chorioamnionitis | not billable |
| Isospora belli or hominis | A07.3 | Isosporiasis | |
| Japanese B encephalitis | A83.0 | Japanese encephalitis | |
| jaw | M27.2 | Inflammatory conditions of jaws | |
| joint NEC | M00.9 | Pyogenic arthritis, unspecified | |
| kidney | N15.9 | Renal tubulo-interstitial disease, unspecified | |
| Klebsiellapneumoniae NEC | A49.8 | Other bacterial infections of unspecified site | |
| kneeNEC | M00.9 | Pyogenic arthritis, unspecified | |
| lancet fluke | B66.2 | Dicroceliasis | |
| larynx NEC | J38.7 | Other diseases of larynx |
Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources