Short CommunicationTransplacental Transmission of Trypanosoma evansi From Experimentally Infected Donkey Mare to Neonatal Foal
Introduction
Trypanosomosis, caused by Trypanosoma evansi, is an important disease of equines causing high morbidity and mortality. Trypanosoma evansi has the widest geographic range of all the pathogenic trypanosome species and is a major constraint to livestock productivity on the three continents Asia, Africa, and South America. Trypanosoma evansi infects a wide range of domestic animals particularly camels, horses, cattle, buffaloes, and pigs [1]. Abortions associated with trypanosomosis have been reported in buffaloes, cattle, pigs, and camels [2], [3], [4], [5], [6].
The equine placenta is diffused epitheliochorial type, and the molecules have to cross maternal endothelium, uterine epithelium, trophoblast, and fetal endothelium to reach fetal bloodstream. The maternal antibodies do not cross the equine epitheliochorial placenta, and newborn foals receive maternal antibodies through colostrum [7]. Trypanosoma evansi is not a strict blood parasite and is capable of invading extravascular tissues of infected animals including brain [8], [9], [10], [11]. Several mechanisms have been proposed by earlier workers to penetrate blood-brain barrier including entrance through incomplete sites such as sensory ganglia and circumventricular organs, deposition of immune complexes in the choroid plexus, increase in vascular permeability, and releasing toxic substances by trypanosomes [12], [13]. An interaction between the trypanosomes and the host may cause placental tissue damage and facilitate parasitic crossing of placental barrier. The present study is an observation of transplacental transmission of T. evansi in a donkey neonatal foal.
Section snippets
Experimental Infection of the Donkey Mare
Trypanosoma evansi isolate was collected from a naturally infected camel and cryopreserved in liquid nitrogen in Parasitology Laboratory, National Research Centre on Equines, Hisar, India. In our earlier experiment, one group of donkey mares was infected experimentally with 2 × 106 trypanosomes per animal subcutaneously. In this experimentally infected group, one donkey mare delivered a normal foal after 3 months of experimental infection. The status of gestation was unknown for this mare at
Clinical and Parasitological Findings
The donkey mare gave a normal birth to a foal after 3 months of experimental infection. Blood samples of the foal (before colostrum feeding) and the experimentally infected donkey mare were collected and tested microscopically by WBF examination. Live moving trypanosomes were observed in foal's blood; however, no parasite was seen in blood of the donkey mare on WBF examination. The microscopic examination of Giemsa-stained blood smear prepared before colostrum feeding shown T. evansi infection
Discussion
The present study is an observation of transplacental transmission of T. evansi infection in a neonatal foal, confirmed by the presence of trypanosomes on microscopic examination of WBF, born to an experimentally infected donkey mare after 3 months of experimental infection. In earlier studies, the presence of T. evansi had been demonstrated in aborted fetuses in naturally infected buffaloes and camels [2], [6]. In one study, transplacental transmission of T. evansi had also been confirmed by
Conclusions
The study indicated the transplacental transmission of T. evansi in a neonatal foal born to an experimentally infected donkey mare. The stage of gestation at which the dam acquires T. evansi infection is important to determine the pathogenesis of reproductive disturbance in equines. To explain the mechanism responsible for crossing the placental barrier by T. evansi in pregnant animals, further detailed study is required.
Acknowledgments
The authors are thankful to the Director, ICAR-National Research Centre on Equines, Hisar, India, for providing necessary research facilities to carry out the present study.
Ethics: All authors certified that in the present work, the animal experimentation was carried out after the approval of Institute Animal Ethic Committee and as per guidelines of the Committee for the Purpose of Control and Supervision of Experiments on Animals, Animal Welfare Division, Government of India.
References (28)
- et al.
An outbreak of abortions and high neonatal mortality associated with Trypanosoma evansi infection in dromedary camels in the Canary Islands
Vet Parasitol
(2005) - et al.
Neurobiology of cerebral malaria and African sleeping sickness
Brain Res Bull
(1997) - et al.
Development of an antibody-ELISA and its application for seroprevalence of Trypanosoma evansi in equids of North and North-western region of India
Vet Parasitol
(2013) - et al.
Experimental Trypanosoma evansi infection in the goat. II. Pathology
J Comp Path
(2005) - et al.
Experimental Trypanosoma evansi infection in South American coati (Nasua nasua): hematological, biochemical and histopathological changes
Acta Trop
(2002) - et al.
Trypanosomiasis of domestic animals in China
Parasitol Today
(1993) - et al.
Molecular evidence for transplacental transmission of Theileria equi from carrier mares to their apparently healthy foals
Vet Parasitol
(2007) - et al.
Passive transfer of Theileria equi antibodies to neonate foals of immune tolerant mares
Vet Parasitol
(2008) - et al.
Oral transmission of Trypanosoma evansi infection in dogs and mice
Vet Parasitol
(1985) Chapter 2.1.17: Trypanosoma evansi infection (surra)
Trypanosoma evansi infection in buffaloes in north-east Thailand. II Abortions
Trop Anim Health Prod
An outbreak of Trypanosoma evansi infection in pigs
J Vet Malaysia
Observations on Trypanosoma evansi infection in neonatal calves
Indian Vet J
Transplacental transmission of trypanosomes in a buffalo calf
Indian Vet J
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2015, Veterinary ParasitologyCitation Excerpt :According to the literature, T. evansi can be mechanically transmitted by bloodsucking insects of Tabanidae and Stomoxidae families and vampire bats (Desmodus rotundus) (Rodrigues et al., 2005, 2009), or orally when carnivores eat infected animals (cannibalism) or by blood from infected animals (Herrera et al., 2004). Transplacental transmission of T. evansi in cattle and buffaloes had been previously reported (Ogwu and Nuru, 1981; Desquesnes et al., 2013), as well as in donkeys (Kumar et al., 2015); however, congenital and mammary transmission has not been described in sheep. The transplacental transmission has also been shown in humans infected by T. cruzi (Andrade et al., 1994), cattle by T. vivax (Batista et al., 2012), and human and dogs by Leishmania chagasi (Boggiatto et al., 2011; Teichmann et al., 2011).
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