Variation in disease phenotype is marked in equine trypanosomiasis

Raftery, A. , Jallow, S., Coultous, R. M. , Rodgers, J. and Sutton, D. G.M. (2020) Variation in disease phenotype is marked in equine trypanosomiasis. Parasites and Vectors, 13, 148. (doi: 10.1186/s13071-020-04020-6) (PMID:32199454) (PMCID:PMC7085162)

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Abstract

Background: Equine trypanosomiasis is a severe and prevalent disease that has the greatest impact globally upon working equids due to its distribution across lower income countries. Morbidity and mortality rates are high; disease management strategies in endemic regions are ineffective and cost prohibitive. Individual variation in disease phenotype in other species suggests host factors could reveal novel treatment and control targets but has not been investigated in equids. Methods: A prospective clinical evaluation of equines presenting for a free veterinary examination was performed in hyperendemic villages in The Gambia. Age, body condition score and body weight were estimated by validated methods, and haematocrit and total protein concentration measured. Animals fulfilling 2 out of 5 clinical inclusion criteria (anaemia, poor body condition, pyrexia, history of abortion, oedema) for a diagnosis of trypanosomiasis received trypanocidal treatment with follow-up at 1 and 2 weeks. Blood samples underwent PCR analysis with specific Trypanosoma spp. primers and results were compared to the subject’s clinical and clinicopathological features. A mixed effects generalised linear model was generated to evaluate the association of infection status with degree of pyrexia and anaemia. Results: Morbidity was high within examined (n = 641) and selected (n = 247) study populations. PCR status was not associated with a defined disease phenotype; there was intra- and inter-species variability. Donkeys were more frequently Trypanosoma spp.-positive (P < 0.001) and febrile (P < 0.001) than horses, but infected horses were more anaemic (P < 0.001), and in poorer body condition (P < 0.001) than donkeys. Sex was correlated to disease phenotype: males were more anaemic (P = 0.03) and febrile (P < 0.001). Haemoparasite co-infections were more common than a single infection. Conclusions: There was evidence of diversity in trypanosomiasis clinical signs plus variable disease phenotypes within equid subpopulations that warrant further investigation. The complex co-infection profile of field cases requires greater consideration to optimise disease management.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Raftery, Alexandra and Sutton, Professor David and Coultous, Dr Robert and Rodgers, Dr Jean
Authors: Raftery, A., Jallow, S., Coultous, R. M., Rodgers, J., and Sutton, D. G.M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:Parasites and Vectors
Publisher:BioMed Central
ISSN:1756-3305
ISSN (Online):1756-3305
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Parasites and Vectors 13: 148
Publisher Policy:Reproduced under a Creative Commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
190648Efficacy of trypanocidal agents in field conditions in working equidae in The GambiaDavid SuttonThe Donkey Sanctuary (DONKEY)Sutton, Dr DavidVets - Veterinary Pathology, Public Health & Disease Investigation
190895Clinical and molecular investigation of CNS trypanosomiasis in working equidae: characterisation of the disease syndromeDavid SuttonThe Donkey Sanctuary (DONKEY)Sutton, Dr DavidVets - Veterinary Pathology, Public Health & Disease Investigation