MHLU - Health Status Resource

Communicable diseases – infections that can spread from one person to another – represent an important burden of illness within the Middlesex-London community.  Among infections transmitted through food or water, campylobacter and salmonella infections were most common, accounting for more than two times the number of all other food- and water-borne enteric diseases reported between 2000 and 2010.

During the 11-year time frame, the number and incidence rate of all food- and water-borne enteric illnesses reported in Middlesex-London were relatively stable or generally declined. However, the highest rates of food- and water-borne infections were among children. It is important to note that this might be due to a truly greater incidence of infections among children, or it might reflect the fact that parents and caregivers are more likely to seek medical attention for young children who are ill, and thereby the specific disease was identified.

Sexually transmitted infections (STIs) were by far the most numerous of all communicable diseases reported in Middlesex-London between 2000 and 2010. Over the 11 years, the number of chlamydia, gonorrhea, and syphilis infections increased dramatically, while newly identified cases of hepatitis C and HIV/AIDS remained relatively stable. Compared to other age groups, teenagers and those in their early 20s experienced the highest incidence rates of chlamydia, gonorrhea, and syphilis, while for HIV/AIDS, those in their 30s had the highest rates of newly identified infections. There were more female than male cases of chlamydia and gonorrhea infections, however, this is likely due to more frequent screening among females and does not necessarily reflect a higher incidence of infections. For hepatitis C, HIV/AIDS and syphilis, the number of male cases outnumbered females.

The incidence rates for chlamydia, gonorrhea, and hepatitis C infections reported in Middlesex-London were higher compared to the province as a whole. Part of this difference may be due to the greater proportion of 20 to 29 year olds in Middlesex-London compared to Ontario, relatively more testing being performed by health care providers in Middlesex-London and therefore more frequent detection of these STIs, or truly greater levels of these infections occurring in the community.

For some communicable diseases, vaccines exist that potentially prevent the occurrence of infection. Due in part to routine immunizations, there were no diphtheria, measles, polio or rubella infections reported in Middlesex-London between 2000 and 2010. Other infections potentially prevented by immunization, such as mumps, pertussis and invasive Streptococcus pneumoniae, occurred at relatively low levels in Middlesex-London during the same time period. The annual average incidence rate of these infections was lower in Middlesex-London compared to Ontario as a whole. Invasive meningococcal disease was the only infection potentially prevented by immunization where the annual average rate for Middlesex-London was greater than the provincial rate.

From 2000 to 2010, influenza was the most common disease occurring in Middlesex-London that was potentially prevented by immunization. As part of a provincial initiative to reduce the occurrence of influenza among vulnerable populations living in long-term care homes (LTCHs), residents and staff of these facilities are targeted for influenza immunization, as well as staff in acute care hospitals. Between 2004/05 and 2010/11, the percent of LTCH residents who were immunized against influenza decreased in both Middlesex-London and Ontario; since 2007/08 the percent in Middlesex-London has been lower than the provincial median. While the percent of LTCH staff immunized against influenza was consistently higher than the percent among hospital staff, between 2004/05 and 2010/11 the percent immunized declined among both LTCH and hospital staff.

There exist a number of other communicable diseases of interest that were followed by the Health Unit between 2000 and 2010. In September 2008 Clostridium difficile infection (CDI) outbreaks in hospitals became reportable to public health officials. In 2009 and 2010, there were more than 80 CDI outbreak associated cases. The majority of CDI cases were females, and with one-third of cases aged 80 years and over, older patients were particularly affected by CDI. Older individuals also accounted for the greatest proportion of invasive Group A Streptococcus (iGAS) infections, with one-third of these cases 60 years of age and over.

Between 2000 and 2010, an average of eight active tuberculosis (TB) infections were reported and followed up per year in Middlesex-London. The corresponding incidence rate of active TB infections was significantly lower than the Ontario rate.

In addition to following up individuals reported to have communicable diseases, the Health Unit also investigates outbreaks of communicable diseases in health care facilities, child care centres, and in the community. On average, over 140 outbreaks were investigated and confirmed per year between 2005 and 2011, with an additional 21 potential outbreaks also investigated per year. The majority of these were enteric or respiratory in nature. Child care centres accounted for more than one in four enteric outbreaks investigated, and the majority of respiratory outbreaks were in LTCHs. Norovirus was the most commonly identified pathogen among confirmed outbreak investigations where an enteric pathogen was identified, while rhinovirus and influenza A were most common among outbreaks where a respiratory pathogen was isolated.