Conradie van Wyk, IlanaGoddard, AmeliaBronsvoort, Barend Mark de ClareCoetzer, Jacobus A.W.Handel, Ian GrahamHanotte, OlivierJennings, AmyLesosky, MaiaKiara, HenryThumbi, Samuel MwangiToye, Philip G.Woolhouse, Mark W.Penzhorn, Barend Louis2014-09-022014-09-022014Van Wyk, IC, Goddard, A., BMDC Bronsvoort, BM, Coetzer, JAW, Handel, IG, Hanotte, O, Jennings, A, Lesosky, M, Kiara, H, Thumbi, SM, Toye, P, Woolhouse, MW & Penzhorn, BL 2014, 'The impact of co-infections on the haematological profile of East African short-horn Zebu calves', Parasitology, vol. 141, no. 3, pp. 374-388.0031-1820 (print)1469-8161 (online)10.1017/S003118201300162535609781000J-7222-2013http://hdl.handle.net/2263/41886The work was done as part of the Infectious Diseases of East African Livestock (IDEAL) project, which is a collaboration between the University of Pretoria, University of Edinburgh, University of Nottingham and the International Livestock Research Institute (ILRI), Nairobi, Kenya.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 sampleswere collected and analysed to determine the infection status of each calf aswell 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.en© Cambridge University Press 2013. The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution licence.Co-infectionPlateletsZebusZebu calvesPacked cell volume (PCV)White blood cell count (WBC)Platelet count (Plt)Article