2016 Halton Region Infectious Disease Report

This report summarizes the incidence of infectious (communicable) diseases that were reported to the Health Department for Halton Region residents in 2016, as well as outbreaks investigated by the Halton Region Health Department in 2016.

Background

The Halton Region Health Department works towards the goal of reducing the incidence of infectious diseases in the community through a variety of programs and services, including investigating individual cases and responding to outbreaks, inspecting retail food services and personal service settings, health promotion campaigns, and providing immunizations and other clinical services.

Reportable infectious diseases are diseases that are required under the Health Protection and Promotion Act to be reported to the local Medical Officer of Health. The 2016 Halton Region Infectious Disease Report summarizes the incidence of infectious diseases that were reported to the Health Department for Halton Region residents in 2016. The report also describes outbreaks investigated by the Halton Region Health Department in 2016. This report reflects the surveillance and health status report function that the Health Department is mandated to perform in to monitor the impact of infectious disease programs and to identify significant or emerging issues.

Key Findings

In 2016, 2575 cases of reportable infectious diseases were reported to the Halton Region Health Department.

The top five most common reportable infectious diseases in Halton in 2016 were:

  • Chlamydial infections
  • Influenza
  • Campylobacter enteritis
  • Salmonellosis
  • Gonorrhoea

Vaccine-preventable diseases are diseases for which an effective vaccine exists. In 2016, 673 Halton residents were diagnosed with a vaccine-preventable disease, accounting for 26% of all reportable diseases this past year. Age-standardized rates of vaccine-preventable diseases in 2016 were similar or lower in Halton compared to Ontario. The most commonly reported vaccine-preventable disease was influenza (609 cases). The true number of influenza cases in the population is likely to be much higher, however, as many people may not seek medical treatment or receive laboratory testing for influenza and therefore cases are not reported.

Food and water-borne diseases are caused by bacteria, parasites and viruses that have found their way into food or water that is being consumed. In 2016, there were 413 reported cases of food and water-borne diseases among Halton residents, accounting for 16% of the total cases of reportable infectious diseases this past year. The most commonly reported food- and water-borne diseases in 2016 were salmonellosis (137 cases) and Campylobacter enteritis (136 cases). Age-standardized rates of food- and water-borne diseases in Halton were similar or lower compared to Ontario. In 2015, 46% of food- and water-borne illnesses with known risk factors in Halton were associated with travel outside of Canada.

Sexually-transmitted and blood-borne infectionsare the most common category of reportable infectious diseases in Halton. In 2016, there were 1414 reported sexually-transmitted infections (STI) and blood-borne infections among Halton residents, accounting for over half (55%) of all reportable diseases in Halton. Chlamydia is the most commonly reported infectious disease in Halton (1081 cases). Other common STIs and blood-borne infections include gonorrhoea (172 cases) and Hepatitis C (95 cases). In general, rates of STIs and blood-borne infections were lower in Halton compared to Ontario. In recent years, Halton has seen an increase in reported cases of gonorrhoea and chlamydia, which reflects the overall trend in Ontario.

Reportable neonatal infectious diseases are transferred from mother to infant either through the placenta, or through the birth canal at the time of birth. In 2016, there was only one case of a reportable neonatal disease.

Zoonotic diseases are diseases that can be passed between humans and animals. Vector-borne diseases are spread to people by small organisms such as mosquitoes and ticks. In 2016, there were 12 zoonotic or vector-borne diseases reported in Halton, accounting for less than 1% of all reportable diseases. The most commonly reported vector-borne disease was Lyme disease (7 cases). Halton only experienced 1 reported case of West Nile virus illness in 2016, which was lower than the previous 5 year average.

There were an additional 62 cases of other reportable diseases (meningitis/encephalitis, group A streptococcal disease, tuberculosis) reported to the Halton Region Health Department in 2016, accounting for 2% of all reportable diseases in Halton. Rates of tuberculosis in Halton in 2016 were significantly lower than Ontario.

Infectious diseases and the social determinants of health

Social determinants of health reflect the social and physical conditions where people live, learn, work, and play. Due to the influence of the social determinants of health, the burden of infectious disease is not evenly distributed across the population. In 2016, the rate of reportable infectious diseases in Halton increased as neighbourhood income decreased.

Outbreak investigations

Health Department staff investigate outbreaks in order to decrease or eliminate health risks presented by infectious diseases. All institutional enteric and respiratory outbreaks are reportable to the Health Department, regardless of whether or not the specific disease is known or reportable.

In 2016, there were 72 confirmed and suspect respiratory outbreaks investigated by the Health Department. The majority of respiratory outbreaks investigated by the Health Department involved long-term care homes (50%), followed by retirement residences (25%), child care centres (15%), unregulated or special homes (7%), and hospitals (3%). The most common agents involved in respiratory outbreaks were rhinovirus (28%), unspecified respiratory agents (21%), and influenza A (14%).

In 2016, there were 43 confirmed enteric outbreaks investigated by the Health Department. The majority of enteric outbreaks investigated by the Health Department occurred in child care centres (53%), followed by retirement residence (19%), long-term care homes (16%), within the community (9%), and in unregulated and special homes (2%). Over half the agents involved in enteric outbreaks were unknown (63%), but the most common known agent was norovirus (33%).