Bovine Theileriosis and Its Control in Japan

Merozoites of Theileria Orientalis Buffeli Reduce Parasitosis Following Challenge by Ticks Infested with T.Orientalis Ikeda

“…It was also observed that 2 calves already serendipitously parasitised with < 500 GC/ul T.orientalis ikeda on arrival at 4 months of age, presumably in utero or post-natally, were also signi cantly "protected" from the rst wave of parasitosis following tick challenge. These outcomes consolidated several older theilerial reports from Japan and Korea (Baek et al, 1982;Minami et al, 1981;Onuma et al, 1997) with T.orientalis sergenti, which has been con rmed as T.orientalis (Stewart et al, 1996). A cryopreserved vaccine containing 2 × 10 8 red blood cells containing T.orientalis [sergenti] per dose "had an inhibitory effect on the clinical manifestation of theileriosis" with a need for proliferation of the inoculum (Ishihara, 1962) but this was not developed further.…”

Approaches to Integrated Parasite Management (IPM) for Theileria orientalis with an Emphasis on Immunity

“…The results from these combined studies indicate that the parasitaemias induced by blood inoculation of single or multiple benign and virulent genotypes of T. orientalis do not reach "clinical" levels and do not produce clinical disease in adult cattle or calves >4 months of age [2,35,59]. A similar situation is apparent in calves infected by intrauterine or colostral transmission in endemic zones; these animals remain asymptomatic carriers [47,60,61]. Around 10% of calves born to infected dams were PCR positive at 3 months of age in Japan, but whether clinical disease occurred was not reported [62].…”

“…Passive infection during gestation or through colostral antibodies do not appear to provide reliable protection against T. orientalis. In Korea, intra-uterine infection with T. orientalis [sergenti] occurred readily, but did not protect against field challenge after birth [60,61]. The same situation occurs in endemic regions of T. orientalis in Australia [22].…”

“…The same situation occurs in endemic regions of T. orientalis in Australia [22]. Calves born of infected dams are not fully protected against tick challenge with T. orientalis, indicating that colostral antibodies are not protective [60,61]. The effect may be due to genetic diversity in genotypes of T. orientalis or in their MPSP genes (and epitopes) [20,99].…”

“…Dose-response studies on blood vaccines have not been completed due to the rather ad hoc history of these trials [36], but several results emphasise that dose may influence the levels of protection generated. Both the passive infection in utero and the transfer of antibody does not appear to provide protective immunity after birth [60,61], and this may be related to low dose infection and the transient time-frame of maternal antibody under consistent tick challenge (Section 4 above). However, the interval between (passive) infection and tick challenge, the intensity of the tick challenge, and nutrition may affect the outcome, with calves consistently parasitized by 3-4 weeks of age [22].…”