1. Marco Teórico
1.7 Sistema Constructivo
1.7.3 Lozas Placas Alveolares
of Health.
Note: Other hepatitis viral infections are not here included as they are not reported as a sexually transmitted infections.
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Introduction
Sexually Transmissible Infections (STIs) are a recognised public health issue in Australia and worldwide. Infection with chlamydia, gonorrhoea, syphilis, hepatitis B, human immunodefi ciency virus (HIV), genital warts or genital herpes* has signifi cant implications for population reproductive and sexual health. Unprotected sex is associated with an increased risk of contracting an STI, and the increasing incidence of several STIs supports the need for targeted interventions which encourage safe sex behaviours. A combination of sexual practices and epidemiologic factors have resulted in STIs presenting more commonly in population sub-groups such as men who have sex with men (MSM), young people and in Aboriginal and Torres Strait Islander communities.1,2
This chapter summarises trends in the diagnosis and notifi cation of STIs in Australia and New South Wales, to the level of NSW Area Health Service where possible. The chapter draws primarily on notifi cations to the national collation of state disease notifi cations (National Notifi able Diseases Surveillance System, NNDSS) and NSW notifi able diseases surveillance systems (Table 7.1).
Table 7.1: Online data sources for sexually transmissible infections
NATIONAL URL
The National Notifi able Diseases Surveillance System Searchable database of all notifi able diseases – excludes HIV, reported through the Kirby Institute
www9.health.gov.au/cda/Source/CDA-index.cfm Communicable Diseases Intelligence (CDI)
Annual surveillance reports
www.health.gov.au/internet/main/publishing.nsf/Content/cda- pubs-cdi-cdiintro.htm
The Kirby Institute (formerly the National Centre for HIV Epidemiology and Clinical Research, NCHECR)
Downloadable summary reports – sexually transmitted and blood borne diseases including HIV/AIDS
Reports for Aboriginal and Torres Strait Islanders
http://hiv.cms.med.unsw.edu.au/
NSW
NSW Public Health Bulletin
Monthly and summary Communicable Diseases Reports Report by NSW Area Health Service
www.publish.csiro.au/nid/226.htm NSW Health Report of the Chief Health Offi cer
Searchable database, downloadable data by disease www.health.nsw.gov.au/publichealth/chorep/index.asp NSW Health Infectious Diseases
Fact sheets Weekly reports
www.health.nsw.gov.au/publichealth/infectious/index.asp
NSW Health A–Z of infectious diseases www.health.nsw.gov.au/publichealth/Infectious/a-z.asp Specifi c Diseases
HIV world statistics
WHO World Health Statistics/Health Status Indicators http://apps.who.int/globalatlas/DataQuery/default.asp
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As a result, nationally and in NSW, STI surveillance data on Aboriginal and Torres Strait people are largely regarded as incomplete.7,8
The NSW Public Health Act (1991) requires that medical practitioners and laboratories notify the NSW Department of Health of certain sexually transmissible infections. Chlamydia, gonorrhoea, hepatitis B and HIV are exclusively notifi able by laboratories, whereas syphilis is notifi able by doctors and laboratories. The NSW notifi able disease data reported in this chapter are only for cases with laboratory evidence of infection that are notifi ed to the NSW Notifi able Conditions Information Management System (NCIMS). National notifi cation data were available for this report to 2008, whereas data for NSW was largely only available to 2007. Donovanosis has not been included in this report as, although notifi able, the disease is currently well controlled and rates have declined from 36 cases nationally in 1998 to 2 cases in 2008.
NSW laboratories are required to notify all newly diagnosed cases of HIV infection to the NSW Health Department.9
In 2008, the standard data collection form was expanded to include more complete information for people with a diagnosis of HIV infection, however these data were not included in this report.
Initiatives to improve the quality of notifi cation data for Aboriginal and Torres Strait Island people have contributed to increased notifi cations in various jurisdictions. Mak and Watkins,5 for example, found that by using data linkage to
confi rm Aboriginality, the proportion of STI and Blood Borne Virus (BBV) notifi cations with missing Aboriginality data was reduced by 74%.
Pathology services for STI testing are reimbursable through several Medicare items:
• 69316 Detection of Chlamydia trachomatis by any method – one test
• 69317 one test described in item 69494 and a test described in 69316
• 69319 two tests described in item 69494 and a test described in 69316
• 69494 Detection of a virus or microbial antigen or microbial nucleic acid – one test
• 69495 two tests described in 69494
• 69496 three or more tests described in 69494 However, Medicare data on STI testing will underestimate testing rates as public sexual health clinics do not claim through Medicare.
Data Limitations
Notifi cation of infectious disease refl ects healthcare seeking behaviours and testing, and screening practices which will vary geographically, demographically and over time. Many infections are asymptomatic and remain undiagnosed, hence notifi cation data will underestimate the true population prevalence of infection. Overall, notifi cation data refl ect:1,3
• the underlying disease burden, transmission rates and disease progression
• changes in health promotion and awareness activities which can, for example, lead to increased safe-sex behaviour and disease prevention or increased testing for asymptomatic disease
• population screening, targeted screening and testing of sub-populations
• changes in testing practice or advances in testing procedures and technology
The quality and extent of information collected varies according to the process of disease notifi cation and whether additional demographic information is
collected or public health follow-up is routinely required. The interpretation of disease rates, and in particular comparisons of rates between places and over time, must take these factors into account.
Similarly, the action of direct health interventions to encourage testing must also be considered, especially in the Australian context when implemented in vulnerable, remote or disadvantaged communities. One instance has been the Federal Government National Sexually Transmissible Infections Strategy (2005)4 which included
a chlamydia screening pilot program targeting sexually active people under 25 years old. Resulting elevated notifi cations, whilst they may bring estimates of prevalence in the target community closer to the true value, may also artifi cially infl ate differences between the target community and other comparable populations not subject to the intervention. Interpretation of apparently infl ated rates of STIs must therefore be made within the context of health interventions and changes in other relevant non-disease factors.
Notifi cation data may further underestimate STI prevalence among Aboriginal and Torres Strait Islander communities both nationally and in NSW.5,6 This results from reduced
access to health services in Aboriginal and Torres Strait communities, and factors inhibiting the identifi cation of Aboriginality.3,4 Epidemiological data are routinely only
presented by Aboriginality where data completeness for Aboriginality exceeds 50 per cent. In NSW, only data for HIV, syphilis and hepatitis meet this criterion.3
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Australia’s place internationally in terms of the impact of STIs refl ects differences in national disease prevalence, surveillance and the effi cacy of preventive interventions and screening programs. While such differences affect direct comparability of STI rates, international comparisons remain valuable as indicators of the general status of STIs in Australia compared to other developed countries. For example, for bacterial STIs in Australia, Canada, the United Kingdom and the United States (Table 7.2):10
• chlamydia was the most commonly notifi ed STI, however the incidence in the United States was substantially higher than Australia, Canada and the United Kingdom
• gonorrhoea rates in the United States were
approximately three times higher than Australia, Canada and the United Kingdom
• the incidence of syphilis was lower than chlamydia and gonorrhoea, with the United States reporting the lowest incidence for syphilis
The United Nations AIDS organization bases international HIV prevalence on estimated adult (15 to 49 year old) prevalence.11 The prevalence of HIV in Australia was similar
to the UK and lower than Canada and the United States (Table 7.3).
7.1 Selected International STI Trends
Table 7.2: Notifi cation rates for bacterial sexually transmissible infections, 2004
Table 7.3: Estimated HIV prevalence (%) among 15 to 49 year olds in selected countries, 2007
COUNTRY RATE PER 100,000 POPULATION
Chlamydia Gonorrhoea Syphilis
Australia 179.3 35.4 3.1
Canada 197.1 28.9 3.5
United Kingdom 174.1 37.3 3.8
United States 319.6 113.5 2.7
COUNTRY PREVALENCE ESTIMATE BOUNDS*
Australia 0.2 0.1–0.3 New Zealand 0.1 <0.1–0.1 Canada 0.4 0.2–0.6 United Kingdom 0.2 0.1–0.5 United States 0.6 0.4–1.0 Africa Botswana 23.9 22.5–24.9 South Africa 18.1 15.4–20.9 Asia Cambodia 0.8 0.7 – 0.9 Japan … <0.1 Vietnam 0.5 0.3 – 0.9
Source: Public Health Agency of Canada. 2004 Canadian Sexually Transmitted Infections Surveillance CCDR 2007; 33S1: 1–69 and National Centre in HIV Epidemiology and Clinical Research. HIV/AIDS, viral hepatitis and sexually transmissible infections in Australia Annual Surveillance Report 2009. NCHECR, The University of New South Wales, Sydney, NSW
* The width of the bounds refl ects the type of epidemic, the quality, coverage and consistency of surveillance and, in generalised epidemics, whether data were available from a population-based survey with HIV testing. See Sexually Transmitted Infections: 2008, 84 (Suppl 1). Source: UNAIDS 2008. Report on the global AIDS epidemic: Executive summary. Joint UN Programme on HIV/AIDS (UNAIDS) 2008.
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Chlamydia is a bacterial STI affecting the cervix and fallopian tubes in women and the urethra in men. In women, untreated chlamydia is associated with Pelvic Infl ammatory Disease (PID), pregnancy complications, neonatal infection and tubal infertility.1,12,13 However, the
evidence regarding the risk of infertility is inconclusive and the long term effects of chlamydia on fertility in particular continue to be debated.14,15
Chlamydia infection is age-related, with rates highest in people younger than 25 years, and is associated with having two or more sexual partners within a 12 month period.1,16-18 The majority of infections are asymptomatic
and consequently undetected, suggesting underestimation of the true extent of infection.19