Case Definitions for Notifiable Diseases

The 1947 Health Act entitles the Minister for Health to specify by regulation the diseases that are infectious diseases and covered by legislation (so-called notifiable diseases). The Principal Regulations are the Infectious Diseases Regulations 1981. The regulations require that a medical practitioner and a clinical director of a diagnostic laboratory, in notifying infectious diseases, shall have regard to the case definitions for infectious diseases circulated by the Health Protection Surveillance Centre (HPSC). Case definition means the set of clinical or microbiological characteristics by which a case of infectious disease is defined. HPSC is responsible for maintaining, updating and circulating the case definitions.

The following sets out the case definitions for the notifiable diseases listed in the Schedule to the Infectious Diseases (Amendment) Regulations 2011 (S.I. No. 452 of 2011), which came into operation on 21 September 2011. The list of notifiable diseases is contained in the Appendix.

The list of notifiable diseases was amended in April 2024 (Infectious Diseases (Amendments) Regulations 2024 (S.I. No. 119) to update the nomenclature of mpox in line with WHO guidance.

The case definitions are based mainly on standardised European case definitions (Commission Decision 2008/426/EC). Where European definitions are not available, definitions from other sources are used or adapted. These other sources include Centers for Disease Control and Prevention (CDC), World Health Organization (WHO) and the European Antimicrobial Resistance Surveillance Network (EARS-Net).

It is expected that some case definitions may be amended from time to time; the up-to-date version of the case definitions and the up-to-date list of notifiable diseases may be found on the website of HPSC (

General principles for the application of the case definitions

Polio - Acute anterior poliomyelitis (Polio virus)
Ano-genital warts (Human papilloma virus)
Anthrax (Bacillus anthracis) 

Bacillus cereus food-borne infection/intoxication (Bacillus cereus) Bacterial meningitis (not otherwise specified) 
Botulism (Clostridium botulinum) 
Brucellosis (Brucella spp.) 

Campylobacter infection (Campylobacter spp.) 
Carbapenemase-producing Enterobacteriaceae (CPE) infection or colonisation
Chancroid (Haemophilus ducreyi) 
Chickenpox-hospitalised cases (Varicella-zoster virus) 
Chikungunya disease (Chikungunya virus) 
Chlamydia trachomatis infection (genital) (Chlamydia trachomatis) 
Cholera (Vibrio cholerae) 
Clostridium difficile infection (Clostridium difficile) 
Clostridium perfringens (type A) food-borne disease (Clostridium perfringens)
Creutzfeldt Jakob diseasevariant Creutzfeldt Jakob disease
Cryptosporidiosis (Cryptosporidium parvum, hominis) 
Cytomegalovirus infection (congenital) (Cytomegalovirus) 

Dengue fever (Dengue virus) 
Diphtheria (Corynebacterium diphtheriae, C. ulcerans, C. pseudotuberculosis (toxin producing)) 

Echinococcosis (Echinococcus spp.) 
Enterococcal bacteraemia (Enterococcus spp. (blood))
Escherichia coli infection (invasive) (Escherichia coli (blood, CSF)) 

Giardiasis (Giardia lamblia) 
Gonorrhoea (Neisseria gonorrhoeae) 
Granuloma inguinale (Klebsiella granulomatis) 

Haemophilus influenzae disease (invasive) (Haemophilus influenzae (blood, CSF or other normally sterile site)) 
Hepatitis A (acute) infection (Hepatitis A virus) 
Hepatitis B (acute and chronic) infection (Hepatitis B virus) 
Hepatitis C infection (Hepatitis C virus) 
Hepatitis E infection (Hepatitis E virus) 
Herpes simplex (genital) (Herpes simplex virus) 
Herpes simplex (neonatal) (Herpes simplex virus)
Human immunodeficiency virus infection (Human immunodeficiency virus) 

Influenza (Influenza A and B virus) 

Klebsiella pneumoniae infection (invasive) (Klebsiella pneumoniae (blood or CSF)) 

Legionellosis (Legionella spp.) 
Leprosy (Mycobacterium leprae) 
Leptospirosis (Leptospira spp.) 
Listeriosis (Listeria monocytogenes) 
Lyme disease (Neuroborreliosis) (Borrelia burgdorferi) 
Lymphogranuloma venereum (Chlamydia trachomatis) 

Malaria (Plasmodium falciparum, vivax, knowlesi, ovale, malariae) 
mcr-positive Enterobacteriaceae
Measles (Measles virus) 
Meningococcal disease (Neisseria meningitidis) 
Mumps (Mumps virus) 

Non-specific urethritis 
Novel or rare antimicrobial resistant organism (NRAO)
Noroviral infection (Norovirus) 

Paratyphoid (Salmonella Paratyphi) 
Pertussis (Bordetella pertussis) 
Plague (Yersinia pestis) 

Pseudomonas aeruginosa infection (invasive) (Pseudomonas aeruginosa (blood or CSF)) 

Q Fever (Coxiella burnetii) 

Rabies (Rabies virus) 
Respiratory syncytial virus infection (Respiratory syncytial virus) 
Rotavirus infection (Rotavirus) 
Rubella (Rubella virus) 

Salmonellosis (Salmonella spp. other than S. Typhi and S. Paratyphi) 
Severe Acute Respiratory Syndrome (SARS) (SARS-associated coronavirus)
Shigellosis (Shigella spp.) 
Smallpox (Variola virus) 
Staphylococcal food poisoning (Enterotoxigenic Staphylococcus aureus) 
Staphylococcus aureus bacteraemia (Staphylococcus aureus (blood)) 
Streptococcus group A infection (invasive) (Streptococcus pyogenes (blood, CSF or other normally sterile site)) 
Streptococcus group B infection (invasive) (Streptococcus agalactiae (blood, CSF or other normally sterile site)) 
Streptococcus pneumoniae infection (invasive) (Streptococcus pneumoniae (blood, CSF or other normally sterile site)) 
Syphilis (Treponema pallidum) 

Tetanus (Clostridium tetani) 
Toxoplasmosis (Toxoplasma gondii) 
Trichinosis (Trichinella spp.) 
Trichomoniasis (Trichomonas vaginalis) 
Tuberculosis (Mycobacterium tuberculosis complex) 
Tularemia (Francisella tularensis) 
Typhoid (Salmonella Typhi) 
Typhus (Rickettsia prowazekii) 

Verotoxigenic Escherichia coli infection (Verotoxin producing Escherichia coli) 
Viral encephalitis 
Viral haemorrhagic fevers 
Viral meningitis 

West Nile fever (West Nile virus) 

Yellow fever (Yellow fever virus) 
Yersiniosis (Yersinia enterocolitica, Yersinia pseudotuberculosis) 

Zika virus infection (Zika virus)