Bacterial communicable diseases

Introduction

This section includes selected communicable diseases that are spread by social and sexual contact and food-borne transmission. While practicing good hygiene and staying home when unwell are effective for many communicable diseases, these actions are particularly effective for gastrointestinal illnesses.

Syphilis

Syphilis is a highly infectious sexually transmissible infection (STI) and multi-stage disease caused by the Treponema pallidum bacteria.¹ It can also be transmitted from mother to baby during pregnancy (congenital syphilis) and can lead to serious and potentially fatal health conditions.

From 2017 to 2021, infectious syphilis notifications remained relatively stable across Queensland (Figure 1):

• 1,080 cases in 2017 (21.9 per 100,000 persons)
• 1,054 cases in 2021 (20.3 per 100,000 persons).

Notifications decreased slightly in 2020 (993 cases). There has been a similar trend nationally and the impact of the COVID-19 pandemic on syphilis rates is not yet known.

In 2020 and 2021, most infectious syphilis notifications in Queensland were in:

• heterosexual First Nations men and women in North Queensland
• men who have sex with men in South East Queensland.

Infectious syphilis notifications continued to be more common in First Nations peoples in Queensland (Figure 2).

From 2020–2021, the number of reported cases in pregnant women and their babies was:

• 65 for infectious syphilis
• 30 for late latent syphilis
• 8 for congenital syphilis (Figure 3).

There has been an ongoing outbreak of infectious syphilis in First Nations peoples which was first declared in January 2011. The outbreak affects Hospital and Health Services (HHSs) in Queensland—Torres and Cape, North West, Cairns and Hinterland, Townsville and Central Queensland.

From January 2011 to December 2021 there were 1,833 notifications of infectious syphilis associated with the outbreak. The outbreak included:

• 1,786 notifications in First Nations peoples and 47 in other Queenslanders
• 10 notifications of congenital syphilis among First Nations peoples associated with the outbreak
• 7 of the 10 congenital syphilis cases resulted in death.

Salmonellosis

Salmonellosis is a disease caused by different strains of the bacterium Salmonella. It generally presents as a gastrointestinal illness but for some patients may cause more serious infections involving the bloodstream and other parts of the body such as bones, joints, tissue surrounding the brain and spinal cord, or the lining of the heart or heart valves.

Salmonella is found in the intestinal tract of domestic and wild animals including poultry and reptiles. Transmission to humans can occur by:

• consumption of contaminated or undercooked foods of animal origin including eggs and meat
• produce contaminated with animal waste
• contact with animals or their environments
• contaminated water.

Eggs and egg products continue to be the largest contributor to foodborne salmonellosis cases in Queensland.^2,3 Following a steady decline in Queensland over the period 2015–2018, Salmonella notification rates have remained relatively stable from 2019 to 2021 (Figure 1).⁴ However, notification rates in Queensland have been consistently higher than the national rates across the past 10 years.⁵

In 2021, there were 3,988 cases (annual notification rate of 77 cases per 100,000 persons) of Salmonella infection notified in Queensland, similar to the 2020 rate. This was 1.8 times higher than the Australian notification rate in 2021 (42 cases per 100,000 persons). Children 0 to 4 years accounted for approximately 35% of cases.

Salmonella outbreaks

In 2021 there were 16 Salmonella outbreaks investigated in Queensland involving 550 or more cases. This included a large prolonged multi-jurisdictional outbreak investigation conducted across seven states and territories from January to May. In total, 585 confirmed outbreak cases of Salmonella infection were identified through whole genome sequencing, of which 220 were Queensland residents.

Extensive environmental investigations and product sampling for microbiological testing at various points along the food chain were undertaken. Epidemiological and environmental traceback investigations identified spring onions as the likely source of infection, with the outbreak strain identified in coleslaw and cut spring onions (used in the coleslaw) produced by a New South Wales manufacturer. The manufacturer sourced their spring onions from a Queensland produce farm. Outbreak control measures included:

• a recall of contaminated product from retail stores
• food safety audits of associated food processors and manufacturers
• temporarily ceasing distribution of spring onions from the implicated farm implementing improved control measures at the farm to reduce the risk of produce being microbially contaminated.

Additional information

Data and statistics

• Communicable disease Notifiable conditions reports are updated weekly and available on the Queensland Health website.

Strategies and general information

• The Queensland Sexual Health Framework and related strategic reports are available on the Queensland Health website.

Section technical notes

• Notifications under-represent the incidence of communicable diseases because notifications depend on:
  • individuals presenting with the disease
  • appropriate tests having been undertaken to confirm a diagnosis
  • results being reported to Queensland Health.
• Laboratories, the source of most notifications, may not record First Nations status, causing under-reporting in First Nations peoples.

References

1. Queensland Health. Syphilis. Queensland Government; 2022.
2. Laidlow TA, Stafford R, Jennison AV, et al. A multi-jurisdictional outbreak of Salmonella Typhimurium infections linked to backyard poultry-Australia, 2020. Zoonoses Public Health. 2022;69(7):835-842. doi:10.1111/zph.12973
3. Munck N, Smith J, Bates J, Glass K, Hald T, Kirk MD. Source Attribution of Salmonella in Macadamia Nuts to Animal and Environmental Reservoirs in Queensland, Australia. Foodborne Pathog Dis. 2020;17(5):357-364. doi:10.1089/fpd.2019.2706
4. The OzFoodNet Working Group. Monitoring the Incidence and Causes of Disease Poentially Transmitted by Food in Australia: Annual Report of the OzFoodNet Network, 2016. Australian Government; 2021. Accessed 22 December 2022.
5. Queensland Health. Notifiable Conditions Register (NoCS). Queensland Government; 2022. Accessed 10 November 2022.