Study gives first lab-based measures of chlamydia, herpes rates in Canada
TORONTO – As many as one in seven Canadians aged 14 to 59 may be infected with herpes simplex type 2 virus and more than 90 per cent of them may be unaware of their status, a new study suggests.
The work provides the first Canadian prevalence estimates for herpes simplex 2 and chlamydia – another sexually transmitted infection – that are based on laboratory confirmed results. Previous estimates were based on data collected from positive cases or screening of people considered to be at high risk of having the infections, a system which may not provide a true picture of the scale of infections.
The research was part of the analysis of urine and blood samples and data collected during the 2009 to 2011 cycle of Statistics Canada’s Canadian Health Measures Survey. The results, which are considered a representative sample of most Canadians in that age group, are based on the study of blood and urine samples taken from roughly 3,250 Canadians.
The study found that under one per cent – 0.7 per cent to be precise – of people tested were infected with chlamydia. Participants were asked if they had ever been diagnosed with a sexually transmitted infection and none of those who tested positive for chlamydia reported having received a diagnosis of an STI.
Of those who tested positive for herpes simplex 2, only six per cent were aware that they carried the virus. The remainder were unaware they were infected.
Although it is a reportable disease, chlamydia is what’s known as a silent infection. Most people have no symptoms. Antibiotics can cure the infection.
In women, infection can lead to infertility or ectopic pregnancies – pregnancies where the fertilized egg begins to develop in a fallopian tube or outside the uterus. In pregnant women, untreated chlamydia is associated with pre-term delivery in some cases. In men, complications are rarer, though infertility can occur.
Herpes simplex 2 is also often an asymptomatic infection, though it can appear as blisters and sores around the genitals, rectum or mouth. There is no cure for herpes, but antiviral treatments can lengthen the time between outbreaks of blisters.
Given the low prevalence of chlamydia in the study, the researchers who studied the data did not do further analyses on it.
For the herpes infections, however, they looked at prevalence based on gender, socioeconomic and educational status, age and racial background.
The findings, released by Statistics Canada in the April issue of Health Reports, show that infection was slightly higher in women than men – 16 per cent versus 11 per cent. The prevalence rose with age, from six per cent in people aged 14 to 34 to 19 per cent in people 35 and older.
The report noted that the Canadian rates for herpes simplex 2 were comparable to those generated by similar studies in the United States, Australia and Britain, though the American and British studies showed slightly higher rates of chlamydia.