Viral communicable diseases

Introduction

This section includes selected viral communicable diseases that are spread by social and sexual contact, by airborne droplets such as by coughing and sneezing, and vector-borne transmission (for example, by mosquitoes). Vaccination was a primary strategy to reduce disease severity from COVID-19, complemented by public health messages to practicing good hygiene and stay home when unwell.

COVID-19

This section provides summary information for COVID-19. A more detailed chronology by wave is included in the COVID-19 feature article.

COVID-19 is caused by the SARS-CoV-2 virus that spreads from person to person primarily through airborne transmission—contact with droplets from an infected person through coughing or sneezing. Touching contaminated fomites or inanimate objects, and then touching the mouth or face can also expose a person to COVID-19. Most Queenslanders who become infected with COVID-19 will experience mild to moderate symptoms and recover without hospitalisation.

In Queensland, as of 31 January 2023, there were 1,636,525 reported cases and 1,757 deaths.^1,2

Queensland COVID-19 age-specific rates per 100,000 persons were highest in 2022 coinciding with relaxing of local restrictions and opening of national and international borders (Table 1). COVID-19 infections:

• were lowest during 2020, increased during 2021 and were substantially higher during 2022
• were higher in those 18 to 29 years during 2020, 2021 and 2022
• showed an increase in average age with each successive wave.³

Source: Queensland Health Notifiable Conditions System

*Rate per 100,000

HIV

Human immunodeficiency virus (HIV) attacks the human immune system and weakens the body’s response to infection. HIV infection is spread by sexual contact, blood contact and mother-to-baby transmission. Untreated HIV can progress to acquired immune deficiency syndrome (AIDS). This is now very rare in Australia.

HIV is a significant, global public health problem. An estimated 38 million people worldwide are living with HIV, with 650,000 people dying from AIDS-related illnesses in 2021.⁴

In Australia, there were around 29,460 people living with HIV⁵ which included 5,850 in Queensland in 2021.⁶

Effective public health strategies to reduce HIV transmission include:

• promoting testing and access to treatment—modern antiretroviral treatment (ART) is so effective at suppressing HIV that people who achieve and maintain viral suppression are unlikely to ever develop AIDS and have effectively no risk of transmitting HIV
• promoting access to HIV preventive measures such as pre-exposure and post-exposure prophylaxis (PrEP and PEP) and condom use and providing sterile injecting equipment
• addressing stigma and discrimination associated with HIV.

Trends

There was a gradual decrease in new HIV cases notified in Queensland in the last decade:

• 2014 (peak): 246 cases (5.2 per 100,000 persons)
• 2021: 124 cases (2.4 per 100,000 persons).⁶

This reflects ongoing implementation of the Queensland Government’s Sexual Health Framework and HIV Action Plan.⁷

Male-to-male sex remained the most common mode of transmission among notified HIV cases. Increases were observed in the proportions of:

• cases attributed to heterosexual sex: 20% in 2016 to 29% in 2021
• late HIV diagnoses: 32% for 2016­–2020 (5-year average) to 47% of new diagnoses in 2021.

There were 5,770 Queenslanders dispensed HIV PrEP in 2021 (Figure 1), which significantly reduces the risk of acquiring HIV. This was more than double the number of Queenslanders who accessed HIV PrEP in 2018 when it was first listed on the Pharmaceutical Benefits Scheme (PBS).

• Nationally, 92% of people diagnosed with HIV are on ART (91% in Queensland, 4,849 Queenslanders on ART).
• Nationally, 98% of people receiving ART are virally suppressed (93% in Queensland, 4,509 Queenslanders achieving viral suppression).

Ross River virus infection

Ross River virus infection (RRV) is the most common and widespread mosquito borne disease in Queensland. RRV causes inflammation and pain in multiple joints that can be severe and lasts two to six weeks. Other symptoms may include fever, fatigue and a red rash on the trunk and limbs. Up to 50% of patients report symptoms up to 12 months after initial infection. A recent review has noted that there has been no death reported that is directly attributed to RRV infection.⁸ RRV infection occurs throughout the year anywhere in Queensland, but notifications are typically highest when:

• temperatures are warm.
• there is enough rain to support mosquito breeding and viral activity.

During the 2019–20 season (Figure 3):

• There were 3,488 RRV infection notifications (annual notification rate 67 per 100,000 persons).
• Females and males accounted for 1,990 (57%) and 1,498 (43%), respectively.
• The median age for cases was 46 years (range 6 to 97) with a peak in the 40 to 49 age group.

Notifications recorded in the 2019–20 season were the highest since the 2014 to 2015 (6,371 cases) outbreak. Compared to other periods, 2019–20 reported cases:

• increased two-fold compared to the 2016­–17 to 2018­–19 average
• were almost four times higher than the 2020–21 to 2021–22 average.

Peak months were April and May 2020 with 61% (2,123) of cases diagnosed during this period. Almost three-quarters of RRV notifications from 1 July 2019 to 30 June 2020 (1,537) were reported from five Hospital and Health Services (HHSs)—Metro North, Sunshine Coast, Metro South, Darling Downs and Townsville.

Additional information

Data and statistics

For the latest information about COVID-19, visit

• Queensland Health COVID-19 in Queensland
• The Australian Government Department of Health and Aging
  • Coronavirus (COVID-19) case numbers and statistics

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.
• Figure 2: Queensland RRV infection notifications, 1 July 2016 to 30 June 2022. Data were extracted on 15 July 2022 with episode dates from 1 July 2016 to 30 June 2022. Financial years were plotted to best display the seasonality of Ross River virus, and to maintain consistency with reporting convention.

References

1. Australian Bureau of Statistics. 2023. COVID-19 mortality in Australia: deaths registered until 31 January 2023. Canberra.
2. Queensland Health. COVID-19 in Queensland. Queensland Government; 2022.
3. Antrobus B, Hales H. Qld cases up 61 per cent as chief health officer warns Covid to go ‘for years.’ NCA Newswire. 2022. Accessed 12 December 2022.
4. UNAIDS. Global HIV & AIDS statistics — Fact sheet. Accessed 3 January 2023.
5. King J, McManus H, Gray R, McGregor S. HIV, Viral Hepatitis and Sexually Transmissible Infections in Australia: Annual Surveillance Report 2022. The Kirby Institute, UNSW; 2022:52. Accessed 3 January 2023.
6. Queensland Health. HIV in Queensland: 2021. Queensland Health; 2022:14. Accessed 16 December 2022.
7. Queensland Health. Queensland Sexual Health Framework. Queensland Sexual Health Framework. 2022. Accessed 3 January 2023.
8. Yuen KY, Bielefeldt-Ohmann H. Ross River Virus Infection: A Cross-Disciplinary Review with a Veterinary Perspective. Pathogens. 2021;10(3):357. doi:10.3390/pathogens10030357