The health authority in South Australia has issued a targeted advisory for gay and bisexual men who have sex with men following detections of a multidrug-resistant strain of Shigella. The organism causes a contagious bowel infection, and public health teams are emphasising practical steps people can take to reduce the chance of becoming unwell or passing infection on to others. This notice summarises what is known about the current clusters, how the illness typically presents, and why some recent infections are harder to treat.
Shigella infection often begins suddenly and can be severe in some people, so early recognition and basic precautions matter. The state’s communicable disease unit is working with community health partners to ensure information reaches groups at higher risk. The objective is to keep people informed about symptoms, transmission routes and the implications of antibiotic resistance so they can seek appropriate care and help limit spread.
Symptoms, incubation and how it spreads
Typical signs of Shigella include sudden onset diarrhoea that may be bloody, abdominal cramps, nausea, vomiting and fever. The incubation period — the time from exposure to symptoms — is commonly between 12 hours and four days, and symptomatic illness usually lasts around four to seven days. Because even a very small number of organisms can cause infection, the disease is considered highly contagious and can move quickly in close-contact networks.
Transmission routes to be aware of
The bacterium spreads through direct contact with an infected person, contact with contaminated food or water, touching contaminated surfaces, or via sexual contact. People are infectious while the bacteria are present in faeces, which is generally for up to 4 weeks after the start of illness. That prolonged shedding means precautions around hand hygiene, bathroom practices and safer sex are central to preventing onward transmission.
Treatment challenges with drug-resistant strains
Most people with uncomplicated Shigella recover with rest and fluid replacement alone, but antibiotics are sometimes needed when symptoms are severe. The present concern is a strain that is multidrug-resistant, meaning some commonly used oral antibiotics no longer work reliably. When oral treatments fail, affected patients may require intravenous antibiotics and hospital care. This change raises the risk of more serious outcomes for those with weakened immunity, young children and older people.
What resistance means for patients
Resistance makes clinical management more complex and increases the likelihood that people will need longer or more intensive treatment. That is why health services are tracking patterns of resistance closely so that laboratory results can guide therapy and public health teams can advise clinicians about best practice. Prompt testing, reporting and linkage to care are therefore essential for anyone with severe symptoms or prolonged diarrhoea.
Local case numbers, surveillance and community outreach
Between 2026 and 2026, South Australia recorded an average of 196 cases of Shigella infection each year, with a small proportion showing resistance to multiple antibiotics. Throughout 2026 five cases of the same multidrug-resistant strain were reported among gay, bisexual and other men who have sex with men (GBMSM). Since the beginning of 2026, there have been six reports of that same strain in South Australia among GBMSM. While the overall number of Shigella notifications is broadly similar to the previous year, the count of drug-resistant infections in 2026 is higher.
Public health action and advice
The Communicable Disease Control Branch (CDCB) continues to monitor resistant cases and uses surveillance data to inform public messaging and responses. CDCB is partnering with SAMESH to deliver targeted health promotion aimed at raising awareness in the community. Practical advice includes strict handwashing after toilet use, careful food and surface hygiene, avoiding sexual activity while symptomatic and seeking medical assessment if someone develops severe or persistent diarrhoea, especially if they belong to higher-risk groups.
Health authorities advise that anyone with symptoms or concerns contact their healthcare provider to discuss testing and management. Clinical teams will use laboratory testing to determine whether antibiotics are appropriate and which agents are likely to be effective. Ongoing surveillance, community outreach and timely clinical care remain the cornerstones of limiting spread and protecting those most vulnerable.