Toxoplasmosis y neosporosis en rumiantes domésticosnormalización de modelos animales y evaluación de nuevos fármacos

Abstract

Toxoplasma gondii and Neospora caninum are apicomplexan parasites very related phylogenetically and considered one of the main causes of infectious abortion in small ruminants and cattle respectively worldwide. However, recently, the importance of N. caninum as causative agent of abortion in sheep has greatly increased. T. gondii in small ruminants and N. caninum in cattle show high prevalence and produce important economic losses as a consequence of the reproductive failure. T. gondii in sheep mainly induces abortion triggered by primoinfection with oocysts during pregnancy, while N. caninum related abortions can be found after infection during pregnancy or recrudescence. For the control of toxoplasmosis in sheep there is a commercial attenuated live vaccine available (ToxovaxTM), which partially reduced T. gondii related abortions. No vaccine is available in the market for the control of neosporosis in cattle, since the only vaccine commercialised so far (Neoguard), based on killed tachyzoites, was withdrawn from the market on account of the low efficacy shown. Concerning treatment, different drug classes such as macrolide antibiotics, polyether ionophore antibiotics, folate inhibitors, quinolones and triazinones have been evaluated in ruminants showing moderate efficacy. Therefore, to date, no drug is available for the treatment of toxoplasmosis and neosporosis in ruminants and the improvement and development of control measures is of paramount importance.