Haemato-biochemical characterization of equine piroplasmosis asymptomatic carriers and seropositive, real-time PCR negative horses

Abel Dorrego; Eliazar Camino; Paloma Gago; Aranzazu Buendia-Andres; Kiara Acurio; Sergio Gonzalez; Lucia de Juan; Fatima Cruz-Lopez

doi:10.1016/j.vetpar.2023.110046

Haemato-biochemical characterization of equine piroplasmosis asymptomatic carriers and seropositive, real-time PCR negative horses

Vet Parasitol. 2023 Oct 5:323:110046. doi: 10.1016/j.vetpar.2023.110046. Online ahead of print.

Authors

Abel Dorrego¹, Eliazar Camino², Paloma Gago³, Aranzazu Buendia-Andres¹, Kiara Acurio¹, Sergio Gonzalez¹, Lucia de Juan³, Fatima Cruz-Lopez⁴

Affiliations

¹ VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain.
² Diagnostica Stago S.L.U., Barcelona, Spain.
³ VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain; Animal Health Department, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
⁴ VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain. Electronic address: fatimacr@ucm.es.

PMID: 37826971
DOI: 10.1016/j.vetpar.2023.110046

Abstract

Equine piroplasmosis (EP) is caused by Theileria equi and Babesia caballi, transmitted by tick vectors. Horses can suffer an acute, subacute, and chronic forms of the disease, with clinical signs such as poor performance, fever, pale mucosal membranes, and jaundice. The diagnosis of EP subclinical cases is complex due to the sensitivity of real-time PCR and the limited parasite load in some carriers, making it challenging to differentiate them from seropositive, PCR negative (S+PCR-) individuals. This study aimed to describe haematological and biochemical changes in asymptomatic EP carriers, EP S+PCR- horses and control horses (EP seronegative and PCR negative). It also investigated potential haemato-biochemical markers to aid in distinguishing true EP carriers alongside molecular and serological tests. A comprehensive haematology and biochemistry profile was conducted on 410 sera and EDTA blood samples, comprising 130 EP positives by real-time PCR and competitive ELISA (cELISA) (carriers), 130 EP negatives by real-time PCR but positive to cELISA (S+PCR-) and 150 EP negative horses to real-time PCR and c-ELISA (controls). Our study confirmed that a haematological and biochemistry profile could help to differentiate between EP carriers/S+PCR- from healthy horses. Carriers and S+PCR- horses showed significant increases in the white blood cell count (WBC), high total proteins (TP) and total globulins (GLOB) concentration, and liver function markers compared to controls. Additionally, the evaluation of uric acid (UA) suggested oxidative stress in carrier horses. However, no useful haemato-biochemical diagnostic markers were identified to aid the challenging differentiation of EP carriers and S+PCR- horses, highlighting the need for improvement in molecular/serological diagnosis for these horses.

Keywords: Biochemistry; Carriers; Diagnosis; Equine piroplasmosis; Haematology.