Health Statistics New South Wales - Chlamydia notifications

Key points: Communicable diseases

• At the end of 2009, 92.1% of children aged 12-15 months in NSW were fully immunised.

• In 2009, 7 cases of meningococcal serogroup C disease were notified; the lowest number of notifications of this vaccine preventable disease since 1991.

• In 2009, 14,923 cases of Chlamydia infection were notified. Notifications of Chlamydia have risen steeply since June 1999 and it is now the most frequently notified communicable disease.

• The number of infectious syphilis notifications have increased from 224 in 2006, to 506 cases in 2009.

• In 2006 and 2007 there were several notable outbreaks of Legionnaires' disease, measles, Hepatitis A, Hepatitis C and Salmonella.

• Influenza pandemic caused by H1N1 virus started in mid June 2009 and peaked by mid July 2009 in NSW. There were around 1500 visits in a week to the Emergency departments of NSW hospitals for influenza-like illness. The usual annual weekly peak number of visits for influenza-like illness is around 150. Unlike in other influenza epidemics, the rates of infection in older adults (aged 60 years and over) were low, which is thought to be due to pre-existing immunity from exposure to similar strains of H1N1 virus in the past.

• Among the most frequently reported notifiable conditions in 2009 were:

• Chlamydia trachomatis infections: 14,923 cases (215.4 per 100,000 population)

• Pertussis: 12,567 cases (185.8 per 100,000 population)

• Hepatitis C: 3,935 cases (56.9 per 100,000 population)

• Salmonella infections: 2,719 cases (38.9 per 100,000 population)

• Hepatitis B: 2,661 cases (38.5 per 100,000 population)

• Conditions in 2009 with the most marked declines compared to previous years included:

• Measles: 19 cases, compared with 39 cases in 2008

• Arboviral infection: 1409 cases, compared to the 1837 cases in 2008 with a decline across all types of arboviral infections

• Haemolytic uraemic syndrome: 4 cases, compared with the 17 cases in 2008, a decrease of 76%

• Mumps: 39 cases, compared with 76 cases in 2008 and 318 cases in 2007

• Psittacosis: 22 cases, compared with 40 cases in 2008

• Rubella: seven cases, a 59% decrease compared with the 17 cases in 2008

• Conditions in 2009, with the most marked increases compared to previous years included:

• Pertussis: 12,567 cases, an increase of 40% compared to the 8,754 cases in 2008 and increase of 500% compared to the 2,098 cases in 2007.

• Cryptosporidiosis: 1,459 cases compared to the 542 cases in 2007, an increase of 170%.

• Hepatitis A: 96 cases compared to 69 cases in 2008, an increase of 40%

• Shingellosis: 153 cases, up from 107 cases in 2008, an increase of over 40%

• Chlamydia trachomatis infections: 14,923 cases, the rate has increased from 168.5 cases per 100,000 in 2005 to 215.4 cases per 100,000 , an increase of 30%.

• Salmonella infections: 2,719 cases up from 2,166 cases in 2005, an increase in rates of notification of 20%.

• Brucellosis: Five cases reported up from one case on 2008.

Introduction: Communicable diseases

Definition and burden of disease in Australia

Communicable or infectious diseases are caused by or are capable of being communicated by infection, that is by an invasion and multiplication of microorganisms in the body tissues. Microorganisms causing disease include viruses, bacteria, parasites and other pathogens. Rapid transmission and multiplication of pathogens in a population lacking immunity is at the basis of epidemics.

In Australia and similar developed countries, infectious diseases are not among the leading contributors to the burden of disease. With improved sanitation, the introduction of antibiotics and immunisation programs, the effects of infectious diseases on Australia's health have reduced markedly over the last century (AIHW Cat. no. AUS 122 2010).

Yet the burden of infectious diseases continues to be considerable in Australia: infections and immunisations account for about 7% of all GP consultations. Around 3-4% of deaths annually are attributed to infection, as are a similar percentage of hospitalisations, including pneumonia, urinary tract infections and gastrointestinal infections. Also, the potential for serious outbreaks continues to present a challenge in public health and requires planning and constant vigilance (AIHW Cat. no. AUS 122 2010).

Public Health Act 1991 and 2010

Under the Public Health Act 1991 and 2010, laboratories, hospitals, medical practitioners, schools and child care centres must notify the NSW Department of Health or their local public health unit of diagnoses of certain diseases. For some diseases a notification triggers a public health response by the public health unit, such as immunisation or prophylactic treatment of contacts. Notifications also provide valuable information that is used for planning and evaluation of prevention programs. Doctors, hospital staff, and laboratory staff reported 70.904 cases of notifiable communicable diseases among NSW residents in 2009 (including 11,308 cases of H1N1 influenza).

The number of notifications received for any particular condition is almost always an underestimate of the number of cases that actually occur. For a condition to be notified a patient must seek medical help, be diagnosed with the condition, in some cases must have the appropriate laboratory tests done and then the diagnosis must be reported to the local public health unit or the Department of Health. Nonetheless, communicable disease notifications provide valuable information on disease patterns in NSW.

References

Australian Institute of Health and Welfare. Australia’s health 2010. Australia’s health series no. 12. Cat. no. AUS 122. Canberra: AIHW, 2010. Available at http://www.aihw.gov.au/publication-detail/?id=6442468376

Public Health Act 1991 and Public Health 2010. Available at http://www.legislation.nsw.gov.au/maintop/view/inforce/act 127 2010 cd 0 N

Interventions: Communicable diseases

Response to notifications under Public Health Act 1991

For some diseases a notification triggers a public health response by the public health unit, such as immunisation or prophylactic treatment of contacts. Notifications also provide valuable information that is used for planning and evaluation of prevention programs.

In NSW, from May to December 2009, 5381 cases of laboratory confirmed pandemic (H1N1) 2009 influenza were reported. Soon after the outbreak first appeared, vaccine development began and by October 2009, Australia was one of the first countries to begin its national vaccination progra (AIHW AUS 122 2010).