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Diseases of public health significance

Infectious diseases can be spread from one person to another, directly or indirectly, through fluid exchange, exposure to vectors, or from the environment.

Niagara Region Public Health receives information about and follows up all reportable diseases as identified in Ontario Regulation 559/91 and under the Ontario Health Protection and Promotion Act. For more information, refer to infectious disease trends in Ontario.

Direct contact and respiratory infections are infectious diseases that can spread:

  • By touching people or objects that have germs on them
  • From a sick person's cough or sneeze.
Diseases Number of cases January - March 2026 Year-to-date 2026 Comparison to three-year average in Niagara
Acute Flaccid Paralysis 0 0 Similar
COVID-19 326 326 N/A
Encephalitis / Meningitis 2 2 Similar
Group A Streptococcal disease, invasive 17 17 Similar
Group B Streptococcal disease, neonatal 0 0 Similar
Influenza A, laboratory confirmed 124 124 N/A
Influenza B, laboratory confirmed 125 125 N/A
Legionellosis 3 3 Similar
Meningococcal Disease, invasive 0 0 Similar
Tuberculosis, active 3 3 Similar

Food, waterborne and enteric infections are infectious diseases that spread by eating or drinking contaminated food or water and not cleaning your hands.

Diseases Number of cases January - March 2026 Year-to-date 2026 Comparison to three-year average in Niagara
Amebiasis 0 0 Similar
Campylobacter Enteritis 21 21 Higher
Cryptosporidiosis 34 34 Higher
Cyclosporiasis 0 0 Similar
Giardiasis 6 6 Similar
Hepatitis A 1 1 Similar
Listeriosis 0 0 Similar
Paratyphoid Fever 1 1 Similar
Salmonellosis 28 28 Similar
Shigellosis 0 0 Similar
Typhoid fever 1 1 Similar
Trichinosis 0 0 Similar
Verotoxin-Producing E. coli Including HUS) 1 1 Similar
Yersiniosis 0 0 Similar

Sexually transmitted and bloodborne infections are spread through sexual contact and exposure to infected fluids, such as semen, vaginal fluid, and blood.

Diseases Number of cases January - March 2026 Year-to-date 2026 Comparison to three-year average in Niagara
AIDS 0 0 Similar
HIV 6 6 Similar
Chlamydia 349 349 Similar
Gonorrhea 61 61 Similar
Hepatitis C 26 26 Similar
Syphilis 39 39 Similar

Vaccine preventable infections can be controlled and / or avoided by getting recommended immunizations.

Diseases Number of cases January - March 2026 Year-to-date 2026 Comparison to three-year average in Niagara
Haemophilus influenzae, invasive 3 3 Similar
Hepatitis B 1 1 Similar
Diphtheria 0 0 Similar
Chickenpox (Varicella) 2 2 Similar
Measles 7 7 Similar
Mumps 1 1 Higher
Pertussis (Whooping Cough) 0 0 Similar
Rubella 0 0 Similar
Streptococcus pneumoniae, invasive 19 19 Similar
Tetanus 0 0 Similar

Vectorborne and zoonotic infections are spread from infected insects or animals.

Diseases Number of cases January - March 2026 Year-to-date 2026 Comparison to three-year average in Niagara
Brucellosis 0 0 Similar
Lyme 1 1 Similar
West Nile Virus 0 0 Similar

Data notes

The three‑year averages are calculated using data from 2023 to 2025 and are rounded to the nearest whole number. These averages help smooth out year‑to‑year fluctuations, so trends are easier to understand. Comparisons are based on the most recent reporting quarter rather than full calendar years, providing a more current snapshot of activity. When “N/A” appears, it means a comparison is not possible because changes in the data collection process prevent a reliable match with previous periods.

All reportable infectious disease data—except for COVID‑19 and influenza—are stored in the provincially mandated Integrated Public Health Information System (iPHIS), and only confirmed cases are included. COVID‑19 and influenza data come from the Public Health Ontario Respiratory Virus Tool, which reports information by epidemiological week. Because epidemiological weeks do not always align with calendar months, slight differences in timing may occur when interpreting monthly trends.

Infectious disease data may not capture all cases. Underreporting can occur due to limited testing availability, evolving case and contact management guidelines, and delays in entering information into provincial systems. These factors should be considered when interpreting trends or comparing data across time.

Data for all charts sourced from Integrated Public Health Information System [2026], except:

Direct contact and respiratory infections: Integrated Public Health Information System [2026] and Public Health Ontario Respiratory Virus Tool [2026]

Vectorborne and zoonotic infections: Integrated Public Health Information System [2025]

Last updated: May 2026

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