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Cryptosporidiosis
Cryptosporidiosis is a gastrointestinal illness caused by Cryptosporidium parasites, primarily C. hominis and C. parvum. Transmission is mainly faecal-oral, with contaminated recreational or drinking water being the most common source due to the parasite’s chlorine resistance and environmental persistence (Zahedi & Ryan, 2020).
Epidemiology
The disease is globally widespread but more severe in low- and middle-income countries where poor sanitation and limited access to clean water increase transmission (Khalil et al., 2021). In high-income nations, exposure often occurs via swimming pools, childcare centres, and animal contact.
In Australia, cryptosporidiosis is notifiable nationwide, with 1,500–2,500 cases reported annually, though underdiagnosis is likely (Department of Health and Aged Care, 2024). Notifications peak in late summer to early autumn, often linked to recreational water use. Outbreaks have implicated public pools, childcare settings, and livestock contact. A major outbreak in 2023 involved over 500 confirmed cases in New South Wales and Queensland, traced to contaminated pools. Public health responses included temporary pool closures, intensified chlorination, and advice to avoid swimming for two weeks after illness (NSW Health, 2023).
Clinical Features and Risk Groups
Symptoms include watery diarrhoea, abdominal cramps, nausea, vomiting, low-grade fever, weight loss, and dehydration. Most healthy individuals recover within 1–2 weeks, but immunocompromised people—such as those with HIV, organ transplants, or undergoing chemotherapy—may experience severe, prolonged illness (Caccio et al., 2023). High-risk groups include young children, aged care residents, animal handlers, and travellers (Khalil et al., 2018). Aboriginal and Torres Strait Islander communities in remote areas may face elevated risk due to inadequate water and sanitation infrastructure (AIHW, 2023; Fletcher et al., 2021).
Diagnosis and Treatment
Diagnosis involves stool analysis via microscopy, antigen detection (e.g. ELISA), or molecular tests such as real-time PCR, which offer high sensitivity and species identification (Poirier et al., 2020). There is no universally effective treatment. Nitazoxanide may help in immunocompetent patients but is less effective for immunocompromised individuals (Caccio et al., 2023). Management is supportive and includes fluid and electrolyte replacement, nutritional support, and immune restoration where applicable.
Prevention
Prevention focuses on hygiene and avoiding exposure. Key strategies include proper handwashing, excluding symptomatic individuals from swimming for two weeks, maintaining pool filtration and UV disinfection, avoiding untreated water, and following infection control protocols when handling animals.
References
- AIHW. (2023). Indigenous health and wellbeing snapshot. Australian Institute of Health and Welfare. https://www.aihw.gov.au
- Caccio, S. M., Chalmers, R. M., & Ryan, U. (2023). Current Opinion in Infectious Diseases, 36(2), 137–145. https://doi.org/10.1097/QCO.0000000000000859
- Department of Health and Aged Care. (2024). National Notifiable Diseases Surveillance System – Cryptosporidiosis. https://www.health.gov.au
- Khalil, I. A., Troeger, C., Rao, P. C., et al. (2018). Morbidity, mortality, and long-term consequences associated with diarrhoea from Cryptosporidium infection in children younger than 5 years: a meta-analyses study. The Lancet Global Health, 6(7), e758–e768. https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(18)30283-3/fulltext
- NSW Health. (2023). Cryptosporidiosis factsheet. https://www.health.nsw.gov.au/Infectious/factsheets/Pages/cryptosporidiosis.aspx
- Poirier, P., Wawrzyniak, I., Cateau, E., et al. (2020). Microbial Pathogenesis, 139, 103858. https://doi.org/10.1016/j.micpath.2019.103858
- Zahedi, A., & Ryan, U. (2020). Research in Veterinary Science, 132, 500–512. https://doi.org/10.1016/j.rvsc.2020.08.016