Section 3 of 8
RESULTS
Abbas H. K. Sray, Ghassan J. K. Al-Abedi, Thuraya Khaled Abdulwahed, Israa M. Essa, Zeid Alsadoon, and Hasanain A. J. Gharban · about 7 minutes
Incidence of tick infestation according to age and sex
Based on clinical examination, the incidence and risk of tick infestation varied significantly according to the age and sex of the study cattle (Table 1). The incidence of tick infestation differed significantly among age groups (p = 0.0149). Cattle aged >3–6 years exhibited the highest infestation rate (36.47%) and RR (0.9388; p = 0.0008), whereas cattle aged <1 year showed the lowest infestation rate (13.53%) and RR (0.2918). Intermediate infestation rates were observed in cattle aged 1–3 years (28.82%) and >6 years (21.18%).
Sex was also significantly associated with tick infestation. Female cattle exhibited a significantly higher infestation rate than males (84.71% vs. 15.29%; p = 0.0039). Likewise, the RR of tick infestation was markedly higher in females (6.3855; p = 0.0001) than in males (0.3335).
Factor | No. (%) | RR | NNT | 95% CI
Age (years) | | | |
<1 | 23 (13.53%) | 0.2918 | 3.045 (Benefit) | 2.425 (Benefit) to ∞ to 4.089 (Benefit)
1–3 | 49 (28.82%) | 0.6932 | 7.839 (Benefit) | 4.585 (Benefit) to ∞ to 27.004 (Benefit)
>3–6 | 62 (36.47%)* | 0.9388*** | 42.046 (Benefit) | 14.537 (Harm) to ∞ to 8.594 (Benefit)
>6 | 36 (21.18%) | 0.4804 | 4.366 (Benefit) | 3.158 (Benefit) to ∞ to 7.073 (Benefit)
p-value | 0.0149 | 0.0008 | – | –
Sex | | | |
Female | 144 (84.71%)** | 6.3855**** | 1.4 (Harm) | 1.556 (Harm) to ∞ to 1.272 (Harm)
Male | 26 (15.29%) | 0.3335 | 3.272 (Benefit) | 2.561 (Benefit) to ∞ to 4.528 (Benefit)
p-value | 0.0039 | 0.0001 | – | –
Molecular detection of T. orientalis
Conventional PCR detected T. orientalis DNA in 21 of 170 (12.35%) cattle blood samples and 16 of 170 (9.41%) corresponding tick samples (Figure 2).
Figure 2: Molecular detection of Theileriaorientalis infection among cattle and their naturally infesting ticks by polymerase chain reaction.
Distribution of T. orientalis infection according to host-related risk factors
The prevalence of T. orientalis infection differed significantly among age groups (p = 0.043) (Table 2). The highest prevalence was observed in cattle aged 1–3 years (14.29%) and >3–6 years (14.52%), whereas lower prevalence was observed in cattle aged <1 year (8.70%) and >6 years (8.33%).
Similarly, cattle aged >3–6 years exhibited the highest OR (1.5376) and RR (1.2676), whereas animals aged >6 years showed the lowest OR (0.5859) and RR (0.6496). These findings indicate that cattle aged >3 to 6 years had the greatest likelihood of T. orientalis infection.
According to sex, male cattle exhibited a significantly higher prevalence of T. orientalis infection than females (19.23% vs. 11.11%; p = 0.0445). Likewise, the OR (1.9048) and RR (1.6129) were significantly greater in males than females (p = 0.0001).
Genetic characterization and phylogenetic analysis of T. orientalis
Sequencing analysis of the detected T. orientalis isolates resulted in the submission of nucleotide sequences to the NCBI GenBank database under the isolate designations IS.HA.C1–IS.HA.C21 for cattle isolates and IS.HA.T1–IS.HA.T16 for tick isolates. The corresponding accession numbers ranged from PX851761.1 to PX851781.1 for cattle isolates and from PX851782.1 to PX851797.1 for tick isolates.
Comparative sequence analysis showed nucleotide identities of 78.76% to 100% for cattle isolates and 98.16% to 100% for tick isolates, with sequence variation of 0.001% to 0.05%. Phylogenetic analyses performed separately for cattle and tick isolates revealed that all cattle-derived T. orientalis isolates clustered closely with the Turkish reference isolate HQ197736.1. In contrast, tick-derived isolates exhibited the highest sequence identity with one Chinese isolate (PQ207062.1) and two Turkish isolates (OR211412.1 and HQ197736.1), suggesting close genetic relationships between Iraqi isolates and geographically neighboring T. orientalis strains (Tables 3 and 4; Figures 3–6).
Factor | Total no. | Positive, no. (%) | OR | RR
Age (years) | | | |
<1 | 23 | 2 (8.70%) | 0.6416 | 0.6989
1–3 | 49 | 7 (14.29%)* | 1.2738 | 1.2054
>3–6 | 62 | 9 (14.52%)* | 1.5376* | 1.2676*
>6 | 36 | 3 (8.33%) | 0.5859 | 0.6496
p-value | – | 0.043 | 0.0001 | 0.0001
95% CI | – | 6.042–16.88 | 0.2614–17.58 | 0.4363–14.74
Sex | | | |
Female | 144 | 16 (11.11%) | 0.5250 | 0.6200
Male | 26 | 5 (19.23%)* | 1.9048**** | 1.6129****
p-value | – | 0.0445 | 0.0001 | 0.0001
95% CI | – | 36.42–66.76 | 7.551–99.81 | 5.192–74.24
Local study isolate | | Global NCBI-BLAST isolate
Name | Accession no. | Isolate | | Accession no. | Host | Country | Identity (%)
IS.HA.C1 | PX851761.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.75
IS.HA.C2 | PX851762.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.69
IS.HA.C3 | PX851763.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.73
IS.HA.C4 | PX851764.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.81
IS.HA.C5 | PX851765.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.24
IS.HA.C6 | PX851766.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.59
IS.HA.C7 | PX851767.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.62
IS.HA.C8 | PX851768.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.71
IS.HA.C9 | PX851769.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 98.76
IS.HA.C10 | PX851770.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.25
IS.HA.C11 | PX851771.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.18
IS.HA.C12 | PX851772.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 98.99
IS.HA.C13 | PX851773.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.45
IS.HA.C14 | PX851774.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.75
IS.HA.C15 | PX851775.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 98.92
IS.HA.C16 | PX851776.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.15
IS.HA.C17 | PX851777.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.68
IS.HA.C18 | PX851778.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.75
IS.HA.C19 | PX851779.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.41
IS.HA.C20 | PX851780.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.62
IS.HA.C21 | PX851781.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.70
Local study isolate | | Global NCBI-BLAST isolate
Name | Accession no. | Isolate | | Accession no. | Host | Country | Identity (%)
IS.HA.T1 | PX851782.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T2 | PX851783.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T3 | PX851784.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T4 | PX851785.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T5 | PX851786.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T6 | PX851787.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T7 | PX851788.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.83
IS.HA.T8 | PX851789.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 99.67
IS.HA.T9 | PX851790.1 | RT4-Sarikamis | | OR211412.1 | Cattle | Turkey | 99.73
IS.HA.T10 | PX851791.1 | Giresun-1 | | HQ197736.1 | Bovine | Turkey | 99.64
IS.HA.T11 | PX851792.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.16
IS.HA.T12 | PX851793.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.87
IS.HA.T13 | PX851794.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.82
IS.HA.T14 | PX851795.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.97
IS.HA.T15 | PX851796.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.86
IS.HA.T16 | PX851797.1 | CQMB-cattle-CQ55 | | PQ207062.1 | Tick | China | 98.82
Figure 3: Multiple sequence alignment showing frequency-based nucleotide differences between cattle- and tick-derived Theileriaorientalis isolates and NCBI-BLAST reference isolates using the NCBI MSA Viewer.
Figure 4: Multiple sequence alignment showing nucleotide sequence alignment of cattle- and tick-derived Theileriaorientalis isolates and NCBI-BLAST reference isolates using the NCBI MSA Viewer.
Figure 5: Phylogenetic tree of cattle-derived Theileriaorientalis isolates and NCBI-BLAST reference isolates. Study isolates are indicated by blue circles, whereas the closely related Turkish isolate (HQ197736.1) is indicated by a red circle.
Figure 6: Phylogenetic tree of tick-derived Theileriaorientalis isolates and NCBI-BLAST reference isolates. Study isolates are indicated by blue circles, whereas the closely related Turkish (red and brown triangles) and Chinese (purple triangle) reference isolates are highlighted.