Passive transfer of Theileria equi antibodies to neonate foals of immune tolerant mares.

Equine babesiosis, a tick transmitted haemoprotozoan disease caused by Theileria equi is globally distributed and responsible for heavy economic losses to the equine husbandry. Equids reared in endemic areas usually pick up infection at an early age and become immune tolerant throughout their life span. We studied the level of passively transferred antibodies in neonate foals born from pre-immuned mares. Latently T. equi infected pre-immuned pony and donkey mares (three each) were selected and T. equi antibody titres in neonates was monitored till 90 days post foaling (DPF) by applying Dot-ELISA on sequentially collected serum samples from foals and their dams. A very high antibody titre was observed in pre-immuned pony and donkey mares. The maximum antibody of 1:60 to 1:80 was observed in pony's and donkey's foal on 2–16 and 2–10 DPF, respectively and thereafter it declined to less than 1:20 on 63–77 and 56–63 DPF. Simultaneously parasite carrying status in neonate foals and their dam was also monitored by applying PCR on blood samples. We could demonstrate PCR amplification in dam's blood samples while no amplification was recorded in neonate's blood samples. This study indicated that new-born foals were born naïve and passively transferred immunity was transitory which wanes after 63–77 DPF.