Clindamycin may help prevent shedding of Toxoplasma gondii oocysts
A way to keep cats with toxoplasmosis from shedding infective oocysts into their environment would be of great benefit since these same oocysts can infect people, especially children, pregnant women, and immunocompromised people. A recent study in Zoonoses and Public Health investigated whether clindamycin would prevent the shedding of Toxoplasma gondii oocysts. The study population consisted of 12 1.5- to 2-month-old kittens that were healthy and showed no evidence of parasitism, including T. gondii. Six of the cats were infected with 40 to 50 T. gondii tissue cysts and served as the positive control. The other six were also infected with 40 to 50 tissue cysts but were treated with oral clindamycin (20 mg/kg/day) for 24 days. The cats were monitored for 30 days, and fecal examinations revealed that all of the control cats shed oocysts, while none of the cats that received clindamycin shed oocysts. Clindamycin was well-tolerated by the kittens.
The researchers further divided the groups 45 days into the experiment to test whether clindamycin would still prevent shedding in the face of immunosuppression. Three of the control cats and three of the cats that had received clindamycin were given parenteral dexamethasone at immunosuppressive doses (1 mg/kg/day) for 30 days. After 30 days of monitoring, the three cats from the control group re-shed oocysts, but those from the experimental group still did not. As a final challenge, the researchers reinfected the three kittens that had received clindamycin but that had not been immunosuppressed and monitored them for 30 days. Two of the three kittens did shed oocysts. The researchers concluded that this experiment can serve as a model for a larger experiment involving more cats, but that the results indicate that as long as infected cats are receiving clindamycin, they will not shed T. gondii oocysts even when severely immunosuppressed.
Malmasi A, Mosallanejad B, Mohebali M, et al. Prevention of shedding and re-shedding of Toxoplasma gondii oocysts in experimentally infected cats treated with oral clindamycin: a preliminary study. Zoonoses Public Health 2009;56(2):102-104.
Link to abstract: http://www3.interscience.wiley.com/journal/121415107/abstract