Frenkel J K, Ruiz A, Chinchilla M
Am J Trop Med Hyg. 1975 May;24(3):439-43. doi: 10.4269/ajtmh.1975.24.439.
Toxoplasma oocysts in cat feces were marked with a tracer amount of strontium-85 (85-SR), and were superficially buried simulating the natural disposal of feces by cats. Oocyst infectivity in Costa Rica was followed qualitatively and persisted for 1 year in three shaded sites, two moist, and one relatively dry site. Oocyst infectivity was quantitated in the Kansas deposit over a period of 18 months, including two winters. After initial mixing in soil, the level of infectivity remained fairly stable. Infectivity was recovered, probably from the surface on one Musca, several isopods, and earthworms. These data on persistence of Toxoplasma oocysts in soil support the concept that Toxoplasma infectivity in nature may be increased logarithmically by cats.
用微量的锶 - 85（85 - Sr）标记猫粪便中的弓形虫卵囊，并将其浅埋，模拟猫自然处理粪便的方式。对哥斯达黎加的卵囊感染力进行了定性跟踪，在三个阴凉地点、两个潮湿地点和一个相对干燥的地点，卵囊感染力持续了1年。在堪萨斯州的沉积物中对卵囊感染力进行了为期18个月的定量分析，包括两个冬季。在土壤中初步混合后，感染力水平保持相当稳定。在一只家蝇、几只等足类动物和蚯蚓的体表可能恢复了感染力。这些关于弓形虫卵囊在土壤中持久性的数据支持了这样一种观念，即自然界中弓形虫的感染力可能会因猫而呈对数增加。
