title: The impact of co-infections on the haematological profile of East African Short-horn Zebu calves.
abstract: The cumulative effect of co-infections between pathogen pairs on the haematological response of East African Short-horn Zebu calves is described. Using a longitudinal study design a stratified clustered random sample of newborn calves were recruited into the Infectious Diseases of East African Livestock (IDEAL) study and monitored at 5-weekly intervals until 51 weeks of age. At each visit samples were collected and analysed to determine the infection status of each calf as well as their haematological response. The haematological parameters investigated included packed cell volume (PCV), white blood cell count (WBC) and platelet count (Plt). The pathogens of interest included tick-borne protozoa and rickettsias, trypanosomes and intestinal parasites. Generalized additive mixed-effect models were used to model the infectious status of pathogens against each haematological parameter, including significant interactions between pathogens. These models were further used to predict the cumulative effect of co-infecting pathogen pairs on each haematological parameter. The most significant decrease in PCV was found with co-infections of trypanosomes and strongyles. Strongyle infections also resulted in a significant decrease in WBC at a high infectious load. Trypanosomes were the major cause of thrombocytopenia. Platelet counts were also affected by interactions between tick-borne pathogens. Interactions between concomitant pathogens were found to complicate the prognosis and clinical presentation of infected calves and should be taken into consideration in any study that investigates disease under field conditions.
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Ilana Conradie
authors.initials: IC
authors.lastname: Van Wyk
authors.affiliation: Clinical Pathology, Department Companion Animal Medicine, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Amelia
authors.initials: A
authors.lastname: Goddard
authors.affiliation: The Roslin Institute at the R (D) SVS, University of Edinburgh, Easter Bush, EH25 9RG, UK.
authors.forename: B Mark
authors.initials: BM
authors.lastname: de C Bronsvoort
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Jacobus A W
authors.initials: JA
authors.lastname: Coetzer
authors.affiliation: The Roslin Institute at the R (D) SVS, University of Edinburgh, Easter Bush, EH25 9RG, UK.
authors.forename: Ian G
authors.initials: IG
authors.lastname: Handel
authors.affiliation: School of Biology, University of Nottingham, Nottingham NG7 2RD, UK.
authors.forename: Olivier
authors.initials: O
authors.lastname: Hanotte
authors.affiliation: The Roslin Institute at the R (D) SVS, University of Edinburgh, Easter Bush, EH25 9RG, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Jennings
authors.affiliation: Department of Production Animal Health, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Maia
authors.initials: M
authors.lastname: Lesosky
authors.affiliation: International Livestock Research Institute, P.O. Box 30709-00100, Nairobi, Kenya.
authors.forename: Henry
authors.initials: H
authors.lastname: Kiara
authors.affiliation: Centre for Immunology, Infection and Evolution, University of Edinburgh, EH9 3JT, UK.
authors.forename: Sam M
authors.initials: SM
authors.lastname: Thumbi
authors.affiliation: International Livestock Research Institute, P.O. Box 30709-00100, Nairobi, Kenya.
authors.forename: Phil
authors.initials: P
authors.lastname: Toye
authors.affiliation: Centre for Immunology, Infection and Evolution, University of Edinburgh, EH9 3JT, UK.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Woolhouse
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Banie L
authors.initials: BL
authors.lastname: Penzhorn
mesh_terms: D000709:Anaplasma / Q000302:isolation & purification; D000818:Animals; D000831:Animals, Newborn; D001403:Babesia / Q000302:isolation & purification; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood* / Q000453:epidemiology; D015331:Cohort Studies; D060085:Coinfection; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D006400:Hematocrit / Q000662:veterinary; D007630:Kenya / Q000453:epidemiology; D007958:Leukocyte Count / Q000662:veterinary; D008137:Longitudinal Studies; D009348:Nematoda / Q000302:isolation & purification; D010273:Parasitic Diseases, Animal / Q000097:blood* / Q000453:epidemiology; D010976:Platelet Count / Q000662:veterinary; D016794:Theileria / Q000302:isolation & purification; D017282:Tick-Borne Diseases / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D013987:Ticks / Q000382:microbiology / Q000469:parasitology; D014345:Trypanosoma / Q000302:isolation & purification