Short communication Passive transfer of Theileria equi antibodies to neonate foals of immune tolerant mares Sanjay Kumar * , Rajender Kumar, A.K. Gupta, S.K. Dwivedi National Research Centre on Equines, Sirsa Road, Hisar 125001, Haryana, India Received 3 September 2007; received in revised form 1 October 2007; accepted 2 October 2007 Abstract 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 naı ¨ve and passively transferred immunity was transitory which wanes after 63–77 DPF. # 2007 Elsevier B.V. All rights reserved. Keywords: Theileria equi; Babesia equi; Passive immunity; Foals; Dot-ELISA; PCR; Maternal antibodies 1. Introduction Equine babesiosis/piroplasmosis, is an acute, sub acute or chronic tick-borne haemoprotozoan disease of the equids (horse, pony, donkey, zebra and mule) caused by intra-erythrocytic protozoa Theileria equi (Mehlhorn and Schein, 1998) and/or Babesia caballi (Nuttal and Strickland, 1910). T. equi is a small piroplasm, measuring 2.0 mm  1.0 mm, whereas B. caballi is a larger form and measures approximately 2.5– 4.0 mm  1.5–3.0 mm. The shape of the T. equi parasite in the infected erythrocyte varies from spherical, elliptical to ovoid. The formation of four daughter parasites generally referred to as Maltese-cross which is very characteristic feature of T. equi. In T. equi infection, clinical parasitaemia may exceed 20% but 1–5% parasitaemia is more commonly observed in field conditions (Kumar and Kumar, 2007). In latent carrier equids, it is very difficult to demonstrate the parasite in stained blood smears as the parasitaemia is extremely low. Equids reared in endemic areas usually pick up infection at early age and become immune tolerant throughout their life span. Nevertheless, relapse of T. equi infection may occur in these equids consequent to unfavorable health conditions. Foals born of pre- immuned mares are naı ¨ve at birth and acquire passive immunity through colostrum (De Waal and Van Heerden, 1994). This immunity is transitory and wanes after a period of time. We studied the duration of this passively acquired immunity in neonate foals and www.elsevier.com/locate/vetpar Available online at www.sciencedirect.com Veterinary Parasitology 151 (2008) 80–85 * Corresponding author. Fax: +91 1662 276217. E-mail address: kumarsanjay66@yahoo.com (S. Kumar). 0304-4017/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2007.10.001