Parasite co-infections show synergistic and antagonistic interactions on growth performance of East African zebu cattle under one year
Ashworth Laboratories, Centre for Infectious Diseases, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, United Kingdom; Roslin Institute, Easter Bush, University of Edinburgh, Roslin, Midlothian EH25 9RG, United Kingdom; International Livestock Research Institute, P.O. Box 30709, Nairobi 00100, Kenya; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private bag X04, Onderstepoort, South Africa; School of Life Science, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom; Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA 99164-7079, United States; KEMRI/CDC Research and Public Health Collaboration, P.O. BOX 1578, Kisumu 40100, Kenya
The co-occurrence of different pathogen species and their simultaneous infection of hosts are common, and may affect host health outcomes. Co-infecting pathogens may interact synergistically (harming the host more) or antagonistically (harming the host less) compared with single infections. Here we have tested associations of infections and their co-infections with variation in growth rate using a subset of 455 animals of the Infectious Diseases of East Africa Livestock (IDEAL) cohort study surviving to one year. Data on live body weight, infections with helminth parasites and haemoparasites were collected every 5 weeks during the first year of life. Growth of zebu cattle during the first year of life was best described by a linear growth function. A large variation in daily weight gain with a range of 0·03-0·34 kg, and a mean of 0·135 kg (0·124, 0·146; 95% CI) was observed. After controlling for other significant covariates in mixed effects statistical models, the results revealed synergistic interactions (lower growth rates) with Theileria parva and Anaplasma marginale co-infections, and antagonistic interactions (relatively higher growth rates) with T. parva and Theileria mutans co-infections, compared with infections with T. parva only. Additionally, helminth infections can have a strong negative effect on the growth rates but this is burden-dependent, accounting for up to 30% decrease in growth rate in heavily infected animals. These findings present evidence of pathogen-pathogen interactions affecting host growth, and we discuss possible mechanisms that may explain observed directions of interactions as well as possible modifications to disease control strategies when co-infections are present. © Cambridge University Press 2013.
Anaplasma; Anaplasma marginale; article; Babesia bigemina; blood parasite; body weight; cattle; Coccidia; cohort analysis; Cooperia; Cryptosporidium; Dictyocaulus; Dictyocaulus viviparous; disease control; environmental factor; Fasciola; growth rate; helminth; helminthiasis; host parasite interaction; livestock; mixed infection; Nematodirus; nonhuman; Oesophagostomum; oesophagostomum radiatum; Ostertagia ostertagi; parasitosis; priority journal; Schistosoma; Strongyloides; Theileria; theileria mutans; Theileria parva; trematode; Trichostrongylus; Trypanosoma; weight gain; Africa, Eastern; Aging; Animals; Cattle; Cattle Diseases; Coinfection; Parasitic Diseases, Animal; Weight Gain