Prevention of Shedding and Re‐Shedding of Toxoplasma gondii Oocysts in Experimentally Infected Cats Treated with Oral Clindamycin: A Preliminary Study

Abstract

This work aimed to evaluate the effects of preventive oral Clindamycin in cats infected with Toxoplasma gondii. Twelve short hair cats were divided into two groups (group 1 and group 2). No titres of T. gondii antibodies were detected in these cats before the experiment. The animals from group 1 were infected with tissue cysts of T. gondii and group 2 were infected and treated with Clindamycin (20 mg/kg/day). The infection was done with almost 40-50 tissue cysts for each cat on day 0. The cats from group 2 were treated with Clindamycin by oral rout for 24 days (from day -3 to day 21). At day 45, the groups 1 and 2 were divided into two subgroups with three animals each. Subgroups 1A and 2A were immunosuppressed with dexamethasone (1 mg/kg/day) for30 days and subgroups 1B and 2B were not immunosuppressed. Faecal exam looking for oocyst shedding was made by 30 days after T. gondii infection, and for 30 days after immunosuppression. All kittens from group 1 shedding oocysts after infection, while animals from group 2 did not shed. After immunosuppression period, all animals from group 1A re-shed oocysts and animals from group 2A remained without shed. However, 2 (66.6%) of the kittens from subgroup 2B shed oocysts 19-20 days after re-challenge. Based on this preliminary study, Clindamycin had a complete inhibitory effect on shedding of oocysts by cats, even under severe immunosuppression, which is a new finding not reported elsewhere.

A Comparative Analysis of Coprologic Diagnostic Methods for Detection of Toxoplama gondii in Cats

“…This sensitive, specific, and robust assay reduces the misclassification of potentially infective cats and the requirement for specialized personnel for epidemiologic surveys. Furthermore, it may be used for the assessment of drugs used to prevent oocyst shedding by T. gondii -infected cats 40 or for monitoring the effectiveness of potential vaccines that would limit oocyst shedding in cats. 41 The results of the present study demonstrate the sensitivity, consistency, and infective-stage specificity of the copro-PCR.…”

Toxoplasma gondii: epidemiology, feline clinical aspects, and prevention

“…Although most cats only shed oocysts once in their lives, following infection, experimental infection and immunosuppression resulted in repeated shedding by kittens 20-21 days following the immunosuppressive event [6]. In addition, oocyst shedding was induced in a non-immunosuppressed kitten following a second inoculation with infected mouse brain homogenate [6]. It is thought that infection to one genotype of T. gondii confers immunity to all genotypes, but this phenomenon has not been explored in cats.…”

“…Following the ingestion of tissue cysts containing bradyzoites, some bradyzoites convert to tachyzoites and some to T. gondii schizonts, which replicate asexually in the intestinal tissue before beginning sexual reproduction ( Figure 1) [5]. Although most cats only shed oocysts once in their lives, following infection, experimental infection and immunosuppression resulted in repeated shedding by kittens 20-21 days following the immunosuppressive event [6]. In addition, oocyst shedding was induced in a non-immunosuppressed kitten following a second inoculation with infected mouse brain homogenate [6].…”

Transmission and Epidemiology of Zoonotic Protozoal Diseases of Companion Animals

“…However, coprophagic animals, including our "best friends," dogs, can transport and subsequently appear to shed T. gondii oocysts (34). Cats are generally thought to actively shed oocysts only after an initial exposure, but immune-suppressive conditions caused by comorbidity or immunosuppressive therapy can result in shedding a second time in young cats after reexposure (15). Seroprevalence rates in U.S. cats vary by location, ranging from 18 to 80%, primarily dependent on climate, with higher seroprevalences in more humid regions (14).…”

“…In other host species, the ingestion of infective oocysts from cat feces or contaminated soil, water, or other materials can lead to the formation of tissue cysts that are infective via the secondary consumption of infected tissues (12,14). Oocysts are shed in large numbers by acutely infected cats once for approximately 2 weeks, except in cases of feline immunosuppression, such as coinfection with feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV), which can result in secondary shedding (15). After shedding, parasite sporulation takes place in 1 to 5 days, providing infective oocysts (13,16).…”