IN HUMANS continued
Confirmation of a diagnosis of relapsing infection in the immunocompromised patient requires molecular testing (e.g. cerebrospinal fluid PCR if neurological signs are present) or the detection of Toxoplasma cysts in a tissue biopsy. • Antenatal screening is not typically recommended in Australia, but serology is performed by some practitioners routinely upon request or based on clinical signs suggestive of acute toxoplasmosis.
• Latent infections have been linked to a wide spectrum of human neurological and psychiatric disorders, with correlations reported for Toxoplasma -seropositivity and conditions including schizophrenia, bipolar disorder, addiction disorders, Alzheimer’s disease, and epilepsy. 21-23 Additional research is required to determine if such associations are causal. • Serological testing is used for the diagnosis of primary and past infection and relies on IgM and IgG testing respectively.
KEY CONSIDERATIONS 1. Most cases of toxoplasmosis in humans are thought to occur indirectly through ingestion of uncooked/undercooked meat or contaminated food, however direct contact with cat faeces is a potential risk. 2. Although cats remain infected for life, shedding is typically of short duration (1-3 weeks) at the time of infection only, unless the cat is re-infected or immunocompromised. Shed oocysts are not immediately infectious, taking one to five days to sporulate. Prompt removal (at least daily) of cat faeces from the environment is recommended. 3. Good hand hygiene is essential after contact with raw meat, soil and sand. This is especially true when handling raw meat and poultry.
Due to the increased risk associated with infection in pregnant women and immunosuppressed individuals, additional precautions should be taken in these groups.
References: 1. Dubey, J.P., (2004) Toxoplasmosis - a waterborne zoonosis. Vet Parasito l, 126(1-2), 57-72. 2. El-Nawawi, F.A., et al (2008) Methods for inactivation of Toxoplasma gondii cysts in meat and tissues of experimentally infected sheep. Foodborne Pathog Dis , 5(5), 687-90. 3. Calero-Bernal, R., et al (2019) Clinical toxoplasmosis in dogs and cats: an update. Front Vet Sci , 6, 54. 4. Montazeri, M., et al (2020) The global serological prevalence of Toxoplasma gondii in felids during the last five decades (1967-2017): a systematic review and meta-analysis. Parasit Vectors , 13(1), 82. 5. Brennan, A., et al (2020) Seroprevalence and risk factors for Toxoplasma gondii infection in owned domestic cats in Australia. Vector Borne Zoonotic Dis , 20(4), 275-280. 6. Dubey, J.P., (2005) Unexpected oocyst shedding by cats fed Toxoplasma gondii tachyzoites: in vivo stage conversion and strain variation. Vet Parasitol , 133(4), 289-98. 7. Hill, D., et al (2002) Toxoplasma gondii : transmission, diagnosis and prevention. Clin Microbiol Infect , 8(10), 634-40. 8. Dantas-Torres, F., et al (2020) TroCCAP recommendations for the diagnosis, prevention and treatment of parasitic infections in dogs and cats in the tropics. Vet Parasitol , 109167. 9. Hartmann, K., et al (2013) Toxoplasma gondii infection in cats: ABCD guidelines on prevention and management. J Feline Med Surg , 15(7), 631-637. 10. Robert-Gangneux, F., et al (2012) Epidemiology of and diagnostic strategies for toxoplasmosis. Clin Microbiol Rev , 25(2), 264-96. 11. Walpole, I.R., et al (1991) Congenital toxoplasmosis: a large survey in western Australia. Med J Aust, 154(11), 720. 12. Karunajeewa, H., et al (2001) Seroprevalence of varicella zoster virus, parvovirus B19 and Toxoplasma gondii in a Melbourne obstetric population: implications for management. Aust NZ J Obstet Gynaecol 41(1), 23-28.
13. Nosaka, K., et al (2020) Seroprevalence and associated risk factors of Toxoplasma gondii infection in a representative Australian human population: The Busselton health study. Clin Epidemiol Glob Health . 14. Gontijo da Silva, M., et al (2015) Prevalence of toxoplasmosis in pregnant women and vertical transmission of Toxoplasma gondii in patients from basic units of health from Gurupi, Tocantins, Brazil, from 2012 to 2014. PLoS One , 10(11), e0141700. 15. Dunn, D., et al (1999) Mother-to-child transmission of toxoplasmosis: risk estimates for clinical counselling. Lancet, 353(9167), 1829-33. 16. Halonen, S.K., et al (2013) Toxoplasmosis. Handb Clin Neurol , 114, 125-45. 17. Gilbert, R., et al (2006) Symptomatic Toxoplasma infection due to congenital and postnatally acquired infection. Arch Dis Child , 91(6), 495-8. 18. McAuley, J.B., (2014) Congenital toxoplasmosis. J Pediatric Infect Dis Soc , 3 Suppl 1, S30-5. 19. Basavaraju, A., (2016) Toxoplasmosis in HIV infection: An overview. Trop Parasitol, 6(2), 129- 135. 20. Rajapakse, S., et al (2017) Prophylaxis of human toxoplasmosis: a systematic review. Pathog Glob Health , 111(7), 333-342. 21. Sutterland, A., et al (2015) Beyond the association. Toxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta-analysis. Acta Psychiatr Scand , 132(3), 161-179. 22. Torrey, E.F., et al (2012) Toxoplasma gondii and other risk factors for schizophrenia: an update. Schizophr Bull , 38(3), 642-647. 23. Milne, G., et al (2020) Toxoplasma gondii : An Underestimated Threat? Trends Parasitol , 36(12), 959-969.
CONTENTS
92 Companion Animal Zoonoses Guidelines
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