title: An observational study of the vertical transmission of Theileria orientalis (Ikeda) in a New Zealand pastoral dairy herd.
abstract: Although only recently recognised, Theileria orientalis (Ikeda) is now the most important infectious cause of anaemia in New Zealand cattle. The aim of this study was to test if vertical transmission of T. orientalis (Ikeda) from dam to calf across the placenta occurs in naturally infected New Zealand dairy cattle and to also test whether the infection status of the dam at calving affects the future susceptibility of its offspring to T. orientalis (Ikeda) infection. Dairy cows (n=97) and their calves were sampled at calving; and the calves again at 4 months of age. All samples were measured for haematocrit and screened for T. orientalis genotypes using a multiplex Buffeli, Chitose and Ikeda specific TaqMan assay. Ikeda positive samples were further tested by singleplex PCR in triplicate to calculate the Ikeda infection intensity as genomes/μl of blood from each infected animal. No T. orientalis (Ikeda) infected calves were born to either T. orientalis (Ikeda) infected or uninfected dams. There were 56/97 dams positive for T. orientalis (Ikeda) infection at calving and 79/90 calves positive for T. orientalis (Ikeda) infection at 4 months of age but no effect on calf susceptibility of dam infection status at calving. There was a significant negative effect of infection intensity on haematocrit after controlling for whether the infected animal was a dam or a 4 month old calf. Vertical trans-uterine transmission of T. orientalis (Ikeda) infection is unlikely in chronically infected dairy cows and thus not a factor in the epidemiology of T. orientalis (Ikeda) infection.
authors.affiliation: Massey University, Palmerston North, New Zealand. Electronic address: K.Lawrence@massey.ac.nz.
authors.forename: K E
authors.initials: KE
authors.lastname: Lawrence
authors.affiliation: Massey University, Palmerston North, New Zealand. Electronic address: K.Gedye@massey.ac.nz.
authors.forename: K
authors.initials: K
authors.lastname: Gedye
authors.affiliation: Ministry for Primary Industries, P.O. Box 40742, Upper Hutt 5018, New Zealand. Electronic address: Andrew.McFadden@mpi.govt.nz.
authors.forename: A M J
authors.initials: AM
authors.lastname: McFadden
authors.affiliation: Ministry for Primary Industries, P.O. Box 40742, Upper Hutt 5018, New Zealand. Electronic address: David.Pulford@mpi.govt.nz.
authors.forename: D J
authors.initials: DJ
authors.lastname: Pulford
authors.affiliation: Massey University, Palmerston North, New Zealand. Electronic address: W.Pomroy@massey.ac.nz.
authors.forename: W E
authors.initials: WE
authors.lastname: Pomroy
mesh_terms: D000740:Anemia / Q000209:etiology / Q000662:veterinary*; D000818:Animals; D000831:Animals, Newborn / Q000469:parasitology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000635:transmission*; D004198:Disease Susceptibility / Q000662:veterinary; D005260:Female; D005838:Genotype; D006400:Hematocrit; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D009520:New Zealand / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D016794:Theileria / Q000235:genetics; D013801:Theileriasis / Q000150:complications* / Q000453:epidemiology / Q000635:transmission*
chemical_list: D012337:RNA, Ribosomal, 18S
keywords: Bovine; Cattle; Ikeda; Theileria associated bovine anaemia; Theileria orientalis; Theileriosis; Vertical transmission