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Middlesex-London Health Unit

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Diseases of Public Health Significance

The Health Unit's Diseases of Public Health Significance Form (PDF) outlines the communicable diseases that must be reported by physicians, laboratories, administrators of hospitals, schools and institutions to the local Medical Officer of Health (as stated in Ontario Regulation 135/18 and Reg. 569 under the Health Protection and Promotion Act R.S.O. 1990, Chapter H.7). The Personal Health Information Protection Act (PHIPA) explicitly allows health care providers to disclose information to the local Medical Officer of Health for purposes outlined under the HPPA.

Reporting Probable or Confirmed Cases of COVID-19 to the Health Unit

Primary care providers should report all confirmed or probable cases of COVID-19 to the Middlesex-London Health Unit (MLHU). Confirmed or probable cases of COVID-19 can be reported to the MLHU in the following ways:

Download: Reportable Disease Notification Form (PDF)

Veterinary Reporting Requirements


Reporting Timelines

The following is a list of Diseases of Public Health Significance that must be reported to the local Medical Officer of Health within the prescribed timelines for reporting.

Immediate Reporting Required

Report ASAP or by next working day


Notify the Middlesex-London Health Unit of a Disease of Public Health Significance

  • 519-663-5317
    Monday to Friday
    8:30 a.m. - 4:30 p.m.
  • 519-663-5317 (option 2)
    After hours, weekends and holidays

Immediate Reporting Required 

(Confirmed and Suspect Cases and Outbreaks)

Immediate reporting is required for the following diseases due to the need for public health follow-up.  Immediate reporting is also required: a) For clusters of any reportable diseases and b) When the Health Unit issues an alert requesting immediate reporting. 


Meningococcal disease, invasive




Paralytic Shellfish Poisoning (PSP)


Paratyphoid Fever

Clostridium difficile associated disease (CDAD) outbreaks in public hospitals


Coronavirus (Novel Coronavirus)



Poliomyelitis, acute

Food poisoning, all causes


Gastroenteritis, outbreaks in institutions and public hospitals


Group A Streptococcal Disease, invasive

Respiratory infection outbreaks in institutions and public hospitals

Haemophilus influenza disease, all types, invasive

Rubella and Congenital Rubella Syndrome

Hantavirus pulmonary syndrome

SARS (Severe Acute Respiratory Syndrome)

Hemorrhagic fevers, including Ebola and Marburg Virus Disease, Lassa Fever & other viral causes


Hepatitis A


Influenza (health care facility cases)


Influenza (Novel, not seasonal)



Typhoid Fever


Verotoxigenic-producing E. coli infection indicator conditions, including hemolytic uremic syndrome (HUS)

Meningitis, acute: bacterial, viral and other causes


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Report as soon as possible, or by next working day 

(Confirmed and Suspect Cases)

Acquired Immunodeficiency Syndrome (AIDS)

Hepatitis C

Acute Flaccid Paralysis (AFP) 

Influenza (Community cases)-





Campylobacter enteritis

Lyme Disease

Carbapenemase-producing Enterobacteriaceae (CPE), colonization or infection  

Ophthalmia neonatorum

Chickenpox, varicella  

Pneumococcal disease (Streptococcus pneumoniae), invasive

 Chlamydia trachomatis infections

Cryptosporidiosis Q fever


Echinococcus multilocularis infection


Encephalitis primary viral, post-infectious, vaccine-related, subacute sclerosing panencephalitis and unspecified Tetanus

Giardiasis (except asymptomatic cases)

Transmissible Spongiform Encephalopathy (e.g. CJD)



Group B Streptococcal disease, neonatal

West Nile Virus

Hepatitis B


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Veterinary Reporting Requirements

Due to increasing number of cases in the province, please be advised that as of January 1, 2018, amendments to O.Reg. 557 (Communicable Diseases – General) under the Health Protection and Promotion Act came into force, which now require veterinarians and directors of veterinary laboratories to report the following animal cases to Middlesex-London Health Unit:

  • Suspect and confirmed cases of avian chlamydiosis
  • Suspect and confirmed cases of avian influenza
  • Suspect and confirmed cases of novel influenza in mammals (defined as any influenza virus not already known to be endemically circulating in Ontario’s animal species)
  • Suspect and confirmed cases of Echinococcus multilocularis infection

To report any of the above, please complete the Veterinary Reportable Disease Form (DOC) and fax to the Middlesex-London Health Unit at 519-663-8241 or call the Health Unit directly at 519-663-5317.

Date of creation: February 28, 2013
Last modified on: August 25, 2020