Factors Affecting Toxoplasma gondii Cyst Survival: A Review for Prevention Strategies

Abstract

Toxoplasma gondii is an obligate intracellular parasite and a zoonosis. It is an opportunistic parasite in both humans and animals, classified under the phylum Apicomplexa due to its complex secretory organelles at the apical end. These organelles facilitate its penetration into host cells. Human infection typically occurs through the consumption of food contaminated with oocysts or undercooked meat or organs containing cysts. Unlike many other diseases, toxoplasmosis often presents no clinical symptoms in both definitive and intermediate hosts.1 Within the intermediate host, Toxoplasma gondii exists in two stages: tachyzoites, which cause acute infection, and bradyzoites, which reside within tissue cysts and can persist for a lifetime. Tachyzoites infect all nucleated cells and multiply by endodyogeny, rapidly spreading throughout the body via the bloodstream or lymphatic system. After approximately two weeks, tachyzoites decrease in number, and bradyzoites develop within host tissues. Bradyzoites can evade the immune system and treatment due to their location within cysts. However, they can revert to tachyzoites if the immune system is compromised, such as in immunosuppressed individuals.2 Research conducted by Hartono revealed that approximately 40% of 50 pork samples contained Toxoplasma cysts.3 These cysts were commonly found in the muscles and internal organs of these animals. Additionally, cysts are prevalent in pets like cats and birds. Cysts are one of the infectious forms of T. gondii and play a significant role in the transmission of toxoplasmosis. The high prevalence of cysts in meat, a common food source, contributes to the ease of human infection. To prevent the transmission of this disease through cysts, extensive research has been conducted on methods to inhibit cyst-mediated transmission of toxoplasmosis. ...