International Comparison

To provide international context for the trends highlighted in this report, the current state of sexually transmitted infections (STIs) in Canada is compared to other western countries with a similar population health status and a well-established public health infrastructure. Countries selected for comparison are the United States, Australia, and United Kingdom. Statistics presented below are either drawn from published health reports or provided directly by respective national health departments. Differences in case numbers and reported rates need to be interpreted with caution due to differences in case definitions, reporting sources, screening programs and screening rates, age groupings and other factors.

Chlamydia

• Chlamydia is the most commonly reported bacterial STI in all four countries. Reported rates of chlamydia infections ranged from 201.8 per 100,000 in United Kingdom to 401.3 per 100,000 in United States (Table 7).
• The United Kingdom only reported uncomplicated genital chlamydia infections whereas other countries reported all laboratory-confirmed clinical isolates, which included both genital and extra-genital specimens. This difference may in part explain the lower rate reported in the United Kingdom.
• In all countries except the United Kingdom, females accounted for at least 60% of all reported cases. The ratio of reported rates between males and females ranged from 1.0:1.0 in United Kingdom to 1.0:2.8 in United States (Table 7).
• In all countries, highest rates were reported in the younger population: 15 to 24 year olds in women and 20 to 24 year olds in men.

Table 7: Reported Cases and Rates of Chlamydia in Canada, Australia, the United Kingdom and the United States, 2008

Country	Number of Chlamydia Cases			Reported Rate of Chlamydia (per 100,000)			M : F Rate Ratio
	Total	Male	Female	Total	Male	Female
Canada*	82,919	27,876	54,967	248.9	168.7	327.4	1.0 : 2.0
Australia*	58,513	23,614	34,784	273.8	222.2	323.8	1.0 : 1.5
United Kingdom	123,018	61,863	61,155	201.8	206.8	196.9	1.0 : 1.0
United States	1,210,523	313,779	893,004	401.3	211.1	583.8	1.0 : 2.8

Gonorrhea

• Reported rates of gonococcal infections were higher in the United States than in other countries (Table 8).
• In the United States, reported rates of gonorrhea were similar in men and women, while in all other countries, reported rates were higher in men than in women; the male-to-female rate ratio ranged from 1.3:1.0 in Canada to 2.1:1.0 in the United Kingdom (Table 8).
• Consistent across countries, the highest rates were reported in young men aged 20 to 24. Among women, highest rates were reported in a slightly younger group in most countries: 15 to 19 year olds in Australia and 16 to 19 year olds in the United Kingdom. In Canada and the United States, however, the highest rate was reported in women aged 15 to 24.

Table 8: Reported Cases and Rates of Gonorrhea in Canada, Australia, the United Kingdom and the United States, 2008

Country	Number of Gonorrhea Cases			Reported Rate of Gonorrhea (per 100,000)			M : F Rate Ratio
	Total	Male	Female	Total	Male	Female
Canada*	12,723	7,092	5,623	38.2	42.9	33.5	1.3 : 1.0
Australia*	7,674	4,988	2,675	35.9	46.9	24.9	1.9 : 1.0
United Kingdom	16,629	11,113	5,516	27.3	37.1	17.8	2.1 : 1.0
United States	336,742	153,103	182,577	111.6	103.0	119.4	1.0 : 1.2

Syphilis

• When compared to chlamydia and gonorrhea infection, infectious syphilis is relatively rare in all four countries. Reported rates ranged from 4.1 per 100,000 in Canada to 9.1 per 100,000 in Australia (Table 9).
• As with chlamydia, the case definition for syphilis varied across countries. In both the United States and the United Kingdom, only primary and secondary infectious syphilis cases were reported. In Australia and Canada, early latent cases were also included in reporting. However, there are notable differences in the definition of early latent syphilis between these four countries. Early latent syphilis is defined as an asymptomatic individual with syphilis who has acquired the infection in the past two years (for UK and Australia) and one year for Canada and the US.
• In all four countries, men accounted for about 85% of reported cases of infectious syphilis. The disparity in reported rates between men and women varied by country; the male-to-female rate ratio ranged from 5.1:1.0 in the United States to 8.3:1.0 in the United Kingdom (Table 9).
• Among men, highest rates ranged: 25 to 39 year olds in Canada, 35 to 39 year olds in Australia, 25 to 44 year olds in the United Kingdom. In the United States, highest rates were reported among 20 to 29 year olds.
• Among women, highest rates were reported in younger populations: 15 to 19 year olds in Australia and 20 to 24 year olds in Canada, the United States and the United Kingdom.

Table 9: Reported Cases and Rates of Infectious Syphilis (Primary, Secondary, Early Latent Syphilis) in Canada and Australia and Primary and Secondary Syphilis in the United Kingdom and the United States, 2008

Country	Number of Syphilis Cases			Reported Rate of Syphilis (per 100,000)			M : F Rate Ratio
	Total	Male	Female	Total	Male	Female
Canada*+	1,394	1,200	190	4.2	7.3	1.1	6.4 : 1.0
Australia*+	1,301	1,152	148	6.1	10.8	1.4	7.7 : 1.0
United Kingdom^	2,524	2,248	276	4.1	7.5	0.9	8.3 : 1.0
United States^	13,500	11,255	2,242	4.5	7.6	1.5	5.1 : 1.0

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