HAEMATO-BIOCHEMICAL, MOLECULAR AND SEROLOGICALSTUDIES ON BABESIA AND THEILERIA SPECIES INFECTIONS OF HORSES IN PARTS OF NORTHERN NIGERIA
HAEMATO-BIOCHEMICAL, MOLECULAR AND SEROLOGICALSTUDIES ON BABESIA AND THEILERIA SPECIES INFECTIONS OF HORSES IN PARTS OF NORTHERN NIGERIA
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Date
2021-05
Authors
IDOKO, Idoko Sunday
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Abstract
Equine piroplasmosis, caused by Babesia caballi, Theileria equi and Theileria haneyi,
is endemic and causes mortality and poor performance of horses in Nigeria, which
oftentimes predispose to misdiagnosis and development of carrier status. This study
sought to characterize the haemato-biochemical alterations in symptomatic and
asymptomatic horses with piroplasmosis, in relation to the parasites‟ biodiversity in
horses. A total of 152 horses, comprising 72 symptomatic and 80 asymptomatic horses
were sampled. Ticks were collected from symptomatic horses for morphological
identification. Blood samples were collected for parasitological, haematological,
biochemical investigations, molecular studies andCompetitive Enzyme Linked
Immunosorbent Assay. Complete Babesia and Theileria 18S rRNA and species-specific
primers were used to amplify the hypervariable regions, equine merozoite antigen-1 and
the coding region on chromosome 1 of the parasites. The PCR positive samples were
sequenced, and those suspected of mixed infections were cloned and sequenced.The
ticks identified were Rhipicephalus evertsi evertsi (58.1 %), Rhipicephalus species
(23.1 %), Amblyomma variegatum (9.2 %), Hyalomma dromedarii (6.4 %), Hyalomma
impeltatum (0.6 %), Hyalomma truncatum (0.2 %), Hyalomma species (0.7 %) and
Boophilus decoloratus (1.6 %).Parasitological examinations of Giemsa-stained thin
blood smears were all negative. The 18S rRNA PCR revealed 54 positive samples,
comparative genomic analysis of the sequences showed five distinct phylogenetic
clades, A, B, C, D and E of Theileria species with eight samples having multi-clades
infection. Symptomatic and asymptomatic horses demonstrated high anti-T. equi
antibodies (84.7 % and 90 %, respectively)while anti-B. caballiantibodies were 0 % and
3.8 % respectively. Three asymptomatic horses, H44 H67 and H78 with mixed B.
caballi and T. equi infections were seropositive to both parasites using cELISA. The mean serum BUN and creatinine concentrations (5.87 ± 1.80 mmol/L and 153.0±38.10
μmol/L, respectively) in B. caballi- and the values (5.87 ± 1.80mmol/L and
153.0±38.10 μmol/L, respectively) in B. caballi-T. equi-infectedasymptomatic horses
were significantly higher (P < 0.05) than T. equi-infected (1.98 ± 0.15 mmol/L and
83.13±3.45μmol/L, respectively) and non-infected (2.01 ± 0.42 mmol/L and
67.65±9.31μmol/L, respectively) asymptomatic horses. The mean plateletcrit (0.16 ±
0.07 %) in symptomatic horses with multi-clade infectionwas significantly higher (P <
0.05) than the values inT. equi andT. haneyi(0.06 ± 0.00 %, 0.07 ± 0.01 %,
respectively) infected horses. Also, mean percent platelet distribution width (PDW) in
T. haneyi-infected horses (14.61 ± 0.10 %) was significantly higher (P < 0.05) than the
value (12.93 ± 0.40 %) in T. equi-infected horses. The mean corpuscular haemoglobin
concentration (MCHC) (32.90 ± 0.80 g/dL), RDW (19.04 ± 0.22 %) were
significantlylower (P < 0.05), while mean lymphocyte counts (6.89 ± 1.08 ×109/L),
mean platelet volume (8.60 ± 0.40 ×103/μL), PDW (14.54 ± 0.11%), serum direct
bilirubin (0.56 ± 0.05 mg/dL) were significantly higher (P < 0.05) in T. equi-infected
symptomatic Mares compared to Stallions (35.60 ± 0.46g/dL, 20.41 ± 0.28 %, 4.03 ±
0.41 ×109/L, 6.92 ± 0.20 fL, 11.84 ± 0.52 %, 0.34 ± 0.04 mg/dL, respectively). The
mean neutrophil counts (4.30 ± 1.20 ×109/L) and concentrations of globulin (7.50 ±
1.83 g/dL) and phosphate (7.80 ± 0.50 mmol/L) were significantly higher (P < 0.05) but albumin (2.90 ± 0.10 g/dL) was significantly lower (P < 0.05) in Geldings compared to
the values in Stallions (1.81± 0.26 ×109/L, 4.27 ± 0.54 g/dL, 3.08 ± 0.42 mmol/L, 6.54
± 0.47 g/dL, respectively) and Mares (1.40 ± 0.62 ×109/L, 3.20 ± 0.53 g/dL, 4.04 ± 0.97
mmol/L, 7.90 ± 0.99 g/dL, respectively). The mean corpuscular volume (MCV) (47.60
± 0.80 fL) was significantly lower (P < 0.05) but MCHC (35.60 ± 0.46 g/dL), RDW
(20.41 ± 0.28 %) and indirect bilirubin (0.73 ± 0.10 mg/dL) inT. equi-infected
symptomatic West African Barb horses were significantly higher (P < 0.05) than the values (50.25 ± 0.74 fL, 33.23 ± 0.61 g/dL, 19.52 ± 0.30 %, 0.38 ± 0.11 mg/dL,
respectively)in Argentine Polo Ponies. The MPV (8.45 ± 0.30 fL), PDW (14.52 ± 0.08
%), serum phosphate (5.06 ± 0.88 mmol/L) and direct bilirubin (0.51 ± 0.05 mg/dL)
concentrations were significantly higher (P < 0.05) in Argentine Polo Ponies than the
values (6.92 ± 0.20 fL, 11.84 ± 0.52 %, 3.08 ± 0.42 mmol/L, 0.34 ± 0.04 mg/dL,
respectively) in West African Barb horses. The study showed remarkable haematobiochemical
alterations in symptomatic horses than asymptomatic horses without
marked oxidative damage. Heterogeneity in the 18S rRNA gene of Theileria speciesin
Nigeria exist. Establishing and domesticating haemato-biochemical reference ranges for
horses in Nigeria as guide to clinical laboratory diagnosis and interpretation is
essential.There is need to carry out routine treatment of horses against piroplasm infection to prevent development of fulminant disease.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF DOCTOR OF PHILOSOPHY IN VETERINARY PATHOLOGY
DEPARTMENT OF VETERINARY PATHOLOGY,
FACULTY OF VETERINARY MEDICINE,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
HAEMATO-BIOCHEMICAL,, MOLECULAR,, SEROLOGICALSTUDIES,, BABESIA,, THEILERIA SPECIES INFECTIONS,, HORSES,, PARTS,, NORTHERN NIGERIA.