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Article

Prevalence of Theileria equi in Horses from Taif and Jeddah, Saudi Arabia, Using Microscopic and ELISA Techniques

by
Mona Ebraheem Albooq
1,2,
Mohammed Othman Aljahdali
1,* and
Noha Talal Zelai
1
1
Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
2
Department of Biology, University College of Duba, Tabuk University, Duba 71911, Saudi Arabia
*
Author to whom correspondence should be addressed.
Parasitologia 2025, 5(2), 14; https://doi.org/10.3390/parasitologia5020014
Submission received: 1 January 2025 / Revised: 2 March 2025 / Accepted: 19 March 2025 / Published: 21 March 2025
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Abstract

:
Equine Piroplasmosis (EP) is a significant tick-borne disease affecting horses, and one of the causative protozoan parasites is Theileria equi, hence the need to understand the prevalence and associated factors influencing it. Considering the population of horses in the study areas, a sample size of 272 horses comprising 171 and 101 horses from Taif and Jeddah was estimated. Thin and thick blood smears were made from the animals’ whole blood for microscopic examination. At the same time, serum samples were prepared and examined for antibodies to antigens using commercial Theileria equi antibody test kit ELISA. The relationships of gender and age with the presence or absence of T. equi parasite infection were determined using the chi-square test. The results revealed no significant association between gender and T. equi prevalence using both microscopic (χ2 = 2.748, p = 0.07) and ELISA (χ2 = 2.412, p = 0.096) diagnostic methods. In Taif, the microscopic results revealed that 86% of female horses tested negative, while 14% tested positive. In contrast, 75% of male horses tested negative, with 25% testing positive for T. equi. In terms of age groups of horses, a significant association (χ2 = 31.966, p = 0.032) between age groups and the prevalence of T. equi in samples from Jeddah using the ELISA method was recorded. Understanding the relationship between the prevalence of T. equi and factors such as gender and age is crucial for developing effective control measures and improving equine health management, especially in Saudi Arabia.

1. Introduction

Equine Piroplasmosis (EP) is a significant tick-borne disease affecting horses, donkeys, mules, and zebras, caused by the protozoan parasites Babesia caballi and Theileria [1]. These parasites are responsible for severe illness in equids, leading to considerable economic losses, particularly in regions where horses play a vital role in transportation, sports, and agriculture [2]. Theileria equi is intraerythrocytic parasites that invade and replicate within the red blood cells of infected animals [3], often resulting in more severe clinical manifestations, including fever, anemia, jaundice, and, in some cases, death [4]. The disease can be present in acute, subacute, or chronic forms, with symptoms ranging from mild lethargy and weight loss to severe cases involving hemolytic anemia and organ failure [5].
The transmission of EP primarily occurs through the bites of infected ticks, which serve as the primary vectors [6]. The most common tick species involved are Rhipicephalus spp., Dermacentor spp., and Hyalomma spp., each with its geographical distribution and host preferences [7].
Makkah province has a worm climate suitable for tick development. Thus, several tick species are found parasitizing domestic animals, including Hyalomma impeltatum H. anatolicum, H. arabica, Boophilus kohlsi and Rhipicephalus turanicus [8,9,10]. Similar species of tick inhabit other regions of Saudi Arabia, with H. impeltatum being the most abundant there [11].
Ticks become infected by feeding on a host with circulating parasites and can then transmit the infection to other equids during subsequent feedings [12]. Additionally, EP can be transmitted iatrogenically through blood transfusions, contaminated needles, and instruments [13]. The disease poses a significant threat to equine health worldwide, particularly in regions with abundant tick populations [14]. EP control and prevention require an integrated approach, including tick control measures and serological screening to detect carriers, quarantine, and treatment protocols for infected animals [15]. Understanding the epidemiology, transmission dynamics, and pathogenicity of Theileria equi is crucial for developing effective strategies to combat this disease [16].
In Saudi Arabia, the vitality of horses is more related to the historical context, as horses have been raised by tribal people for thousands of years in the Arabian Peninsula [17]. Moreover, the Saudi populace is interested in participating in equestrian championships. However, there is insufficient information about horse piroplasmosis in the Middle East and Saudi Arabia. Although Alanazi et al. [18] studied the occurrence of piroplasmosis infection with T. equi in the central province of the Kingdom of Saudi Arabia using an indirect fluorescent antibody (IFA) assay, they collected sera from 241 healthy adult horses in six locations and discovered 4.7–16.5 % of horses were infected with T. equi.
Due to the reports that Equine piroplasmosis is a significant disease affecting equine populations worldwide, in this study, we hypothesized that the association between the prevalence of T. equi with horse gender and age is not significant both in Taif and Jeddah using microscopic and ELISA diagnostic methods. To answer that, this study aims to evaluate the prevalence of T. equi in horses from Taif and Jeddah, Saudi Arabia, using microscopic and ELISA techniques. Understanding the relationship between the prevalence of T. equi and its differences in gender and age is crucial for developing effective control measures and improving equine health management, especially in Saudi Arabia. T. equi and equine piroplasmosis can significantly impact Saudi Arabia’s equine industry by causing reduced performance, increased veterinary costs, and trade restrictions on infected horses [16]. Considering breeding programs and racing events, the disease may lead to economic losses for horse owners and stakeholders in Saudi Arabia, hence the need for effective surveillance and control strategies crucial to mitigate these economic and practical challenges [17].

2. Materials and Methods

2.1. Study Area

The research was conducted in Makkah province, the western part of Saudi Arabia, in Jeddah and Taif areas. Jeddah is 1600 km2 in area, located between 21.4858° N and 39.1925° E. Taif is located between 21.2854° N and 40.4260° E, with a land mass of 321 km2. Taif is known for its cool climate, scenic mountains, and agricultural significance. The study population was drawn from non-institutional stables including from various traditional and private livestock farms. The study period spanned about one year, from September 2022 to August 2023 (Figure 1).

2.2. Blood Sample Collection

Blood samples were collected from the randomly selected horse population investigated in this study (Table 1). Considering the population (86,786 animals) of horses in the study areas, a sample size of 272 horses from Taif and Jeddah was estimated [19]. A blood sample of around 10 mL was taken from each animal using the jugular vein puncture; 5 mL was placed into a vacutainer tube with ethylenediaminetetraacetic acid (EDTA) tubes for hematological examinations, while 5 mL without anticoagulant was collected for ELISA detection of equine piroplasmosis. The blood samples were centrifuged at 1500 rpm for 10 min, and the serum was separated from the blood. Hemolysis was replaced and eliminated. The serum was stored at −20 °C. An enzyme-linked competitive immunosorbent assay (cELISA) involved a serological test for anti-T. equi. During sample collection, information on animal variables such as breed, age, sex, and collection date was recorded [20,21].

2.3. Microscopic Examination of Equine Piroplasmosis

Thin and thick blood smears were made from the animals’ whole blood, stained with Giemsa (Crescent Diagnostic, Saudi Arabia), and examined under a light microscope (Primo Star, ZEISS, Jena, Germany) to check for the blood parasites, Theileria equi [22].

2.4. Competitive Enzyme-Linked Immunosorbent Assay (cELISA)

Serum samples were examined for antibodies to antigens using commercial Theileria equi antibody indirect test kits cELISA (VMRD, Inc., Pullman, WA, USA). Sample processing, application and interpretation were performed in accordance with the manufacturer’s instructions [23].
The serum samples, reagents, and plates were brought to room temperature (23 ± 2 °C) prior to commencement of the test. The examination of the sera and the reference negative and positive control sera were diluted 1/2 in Serum Diluting Buffer. The positive control was loaded in duplicate, while the negative control was loaded in triplicate at volume of 50 μL. Also, the diluted samples were added in amounts of 50 μL to the wells of the microtiter plates and gently shaken to remove any loose material from the wells. The plates were then covered with plastic lids and incubated for 30 min at room temperature (23 ± 2 °C). The plates were washed (ELx 50, BIO-TEK, Winooski, VT, USA) three times in a washing solution (300 μL/well each time) at room temperature. The plates were lightly tapped to eliminate any remaining washing solution after the washing.
Following the addition of 50 μL of freshly diluted (1×) primary antibody to each well, the plate was incubated for 30 min at room temperature (23 ± 2 °C), and the secondary antibody-peroxidase conjugate was added in an amount of 50 μL of diluted (1×) to each well and incubated for 30 min at room temperature. The plate was washed 3 times, and after the addition of 50 μL of freshly made chromogen substrate solution to each well, the plates were shaken gently and incubated at room temperature for 15 min until the color reaction was stopped by adding 50 μL/well of the stop solution. A microplate reader (ELx 800, BIO-TEK, USA) measured each well’s absorbance at 630 nm. Result interpretation was validated upon the points recommended by the manufacturer and percent inhibition (%I) was calculated by using the following formula:
Percent Inhibition (% I): = 100 − [(Sample O.D. × 100) ÷ (Mean Negative Control O.D.)].
The test sample producing ≥40% inhibition was declared positive, and samples producing <40% inhibition were considered negative.

2.5. Data Analysis

The data were subjected to Leven’s test of homogeneity of variance and the Shapiro-Wilk test for normality before the analyses. Absolute frequencies and percentages (%) were calculated using Office Excel (version 2019). The relationships of gender and age with the presence or absence of T. equi parasite infection were determined using the chi-square test (univariate analysis) for discrete variables at a 95% confidence interval. Since our results involve categorical variables such as gender and age groups, chi-square is an appropriate test for assessing associations between these factors and Theileria equi prevalence. A Principal Component Analysis biplot was used to determine the relationship between T. equi in Arabian and English breeds of horses using microscopic and ELISA diagnostic tests and the relationship between T. equi in male and female horses using microscopic and ELISA diagnostic tests.
R statistics for Windows v.4.0.3 and Statistical Package for the Social Sciences (SPSS) software v.23 were used for analysis.

3. Results

3.1. Theileria equi in Male and Female Horses from Taif and Jeddah City

In this study, male and female horses sampled from Taif and Jeddah were assessed for the prevalence of Theileria equi, considering gender. The general prevalence of 39.3% and 26.8% for microscopic and ELISA methods was recorded in Taif city. In addition, the results presented in Table 2 describe the prevalence of T. equi in male and female horses from Taif city, using microscopic and ELISA detection methods. The microscopic results revealed that 85.7% of female horses tested negative, while 14.3% tested positive. In contrast, 75.0% of male horses tested negative, with 25.0% testing positive for T. equi. However, it is important to note that this disparity in prevalence between genders is not statistically significant (χ2 = 2.748, p = 0.07), indicating that the microscopic method reveals a marginal notable association between gender and the presence of T. equi. Similarly, the ELISA method shows distinct patterns in T. equi prevalence. For female horses, 82.5% tested negative, and 17% tested positive. Among male horses, a higher percentage tested negative (90.7%), while 9% tested positive. So, also, there was no significant association between gender and T. equi prevalence, p ˃ 0.05 (χ2 = 2.412, p = 0.096) (Table 2).
The likelihood ratio for microscopic (2.872) and ELISA (2.334) methods further confirms the non-significant association between gender and T. equi prevalence. Fisher’s Exact Test yields p-values of 0.07 for microscopic and 0.096 for ELISA, approaching but not reaching statistical significance (Table 2).
The prevalence of T. equi in male and female horses in Jeddah, using microscopic and ELISA methods, is presented in Table 3. In the microscopic analysis, 71.8% of female horses tested negative for T. equi, while 28.2% tested positive. Conversely, a higher proportion (83.3%) of male horses tested negative, with only 16.7% testing positive. No significant association exists between gender and the prevalence of T. equi using the microscopic method (χ2 = 1.498, p = 0.1659). The likelihood ratio of 1.58 further supports these findings. Even though there appears to be a trend toward a higher prevalence in females, caution is needed in drawing strong conclusions due to the non-significant association (p = 0.1659). Similarly, no significant association (χ2 = 1.498, p = 0.1659) was recorded for the ELISA method, revealing 43.7% of female horses tested negative, while 56.3% tested positive. Among male horses, 60.0% tested negative, and 40.0% tested positive. The likelihood ratio of 2.2629 further supports this observation. While the ELISA method shows a potential link between gender and parasite prevalence, the results are not significant (p ˃ 0.05).

3.2. Prevalence of Theileria equi Across Different Age Groups of Horses from Taif and Jeddah City

The prevalence of T. equi across different age groups of horses sampled from Taif using microscopic and ELISA methods for determination is described in Table 4. The microscopic results showed a variation in T. equi prevalence across different age groups but it was not significant (p ˃ 0.05). The chi-square reveals a marginal statistically significant association between prevalence and age for microscopic parasite detection (χ2 = 6.261). In addition, the likelihood ratio of 9.117 further supports this, indicating a marginal association. Specifically, as the horse age increases, there is a decreasing trend in T. equi prevalence, with older horses showing a higher percentage of negative results (Table 4). For instance, in age group 8, all horses (100%) tested negative for T. equi using the microscopic method (Table 4).
Similar trends were observed with the ELISA method, with the chi-squared test indicating a slight marginal statistically significant association between age and T. equi prevalence (χ2 = 5.633), even though the p-value (p ˃ 0.05) indicates otherwise. The likelihood ratio of 6.125 supports the association revealed by the chi-square value. Again, older horses tended to have a higher proportion of negative results when the ELISA method of detection or determination was used (Table 4). Notably, in age groups 6 (100%) and 8 (100%), all horses tested negative for T. equi using the ELISA method. Both methods show a consistent trend of decreasing T. equi prevalence with increasing age. However, it is worth noting that the ELISA method revealed positive samples; even in the age groups where all horses tested negative using the microscopic method, a few horses tested positive with ELISA.
The results for T. equi prevalence in different age groups of horses sampled from Jeddah using the microscopic and ELISA methods are described in Table 5. The description of the results of the microscopic method revealed non-association between age and T. equi prevalence in terms of age group. The chi-squared test reveals a highly significant association (χ2 = 15.678, p ˃ 0.05), indicating that the likelihood of a horse testing positive for T. equi varies significantly across different age groups. The likelihood ratio of 34.479 further supports this strong association. Notably, horses, such as those aged 1.5, 4, 5, 11, 12, and 16, were 100% negative for T. equi and exhibited a lower likelihood of testing positive.
In comparison, horses aged 2.5 and 13 years were 100% positive for T. equi, with a higher likelihood of positive results when using the microscopic method (Table 5). The Fisher’s Exact Test provides a p-value of 0.032, indicating statistical significance. Conversely, the ELISA method showed a clear significant association between age and T. equi prevalence, as indicated by the chi-squared test (χ2 = 31.966, p = 0.032) (Table 5), even though a marginal association may exist. The likelihood ratio of 18.7581 further supports this association. Interestingly, age groups 1.5 and 4 exhibit 100.0% positive results with the ELISA method, demonstrating the potential sensitivity of this method in detecting T. equi in horses of various ages. The Fisher’s Exact Test did not show statistical significance (p = 0.67862), suggesting a slightly weaker association compared to the microscopic method. Both the microscopic and ELISA methods demonstrate a significant association between age and T. equi prevalence. The likelihood ratios for both methods are relatively high, emphasizing the strength of these associations.

3.3. Relationship Between Theileria equi and Age of Horses Using Microscopic and ELISA Diagnostic Tests

Figure 2 show a Principal Component Analysis (PCA) biplot for the relationship between Theileria equi in male and female horses and two diagnostic tests (microscopic and ELISA). Components 1 and 2 in this PCA accounted for a total variation of 96 %. The efficiency of the diagnostic test method and the presence of T. equi were shown to have a relationship with the horse’s gender. However, the ELISA diagnostic tests positively correlated with T. equi in male horses, even though the positive relationship was weak. In contrast, the microscopic diagnostic test method was positively correlated with T. equi in the female horses.

4. Discussion

4.1. Gender Influence on the Prevalence of Theileria equi in Horses

In this study, the non-statistically significant (χ2 = 2.748, p = 0.07) difference recorded in this study suggests that microscopic examination did not present strong evidence of an association between gender and the prevalence of T. equi [18]. The lack of a significant association between the prevalence of T. equi and gender and gender differences using the ELISA detection method may be due to several factors, including sample size, geographic variation, and environmental conditions affecting exposure to ticks, which are the vectors of the parasite [18].
The marginal p-values obtained (0.07 for microscopic and 0.096 for ELISA) suggest that while there may be some trend toward gender-related differences, these are not robust enough to be considered statistically significant under conventional thresholds (p < 0.05). This implies that any gender-related differences in T. equi prevalence in this population are likely minimal or may require a larger sample size or different methods to detect [24]. The implications of these findings are significant for understanding the epidemiology of T. equi in different horse populations. If gender does not significantly influence the prevalence of T. equi, as our study suggested, management and control strategies should not necessarily differ between male and female horses [25]. However, the borderline p-values suggest that continued research with larger sample sizes or in different environments might reveal more subtle differences. Our findings align with several previous studies. For example, research by Aziz and Al-Barwary [17] reported no significant differences in T. equi prevalence between male and female horses, indicating that gender may not be a significant factor in susceptibility to this parasite. Similarly, Le Coeur et al. [26] found comparable rates of infection across genders, supporting the idea that factors other than gender, such as tick exposure or breed, might play a more critical role in determining infection rates.
Conversely, some studies have found results that are not in line with ours. For instance, Raftery et al. [27] reported a higher prevalence of T. equi in female horses compared to males, suggesting that physiological or hormonal differences could influence susceptibility. Another study by Zaid [28] observed a higher prevalence in male horses, attributed to behavioral factors, such as increased movement in tick-prone areas, potentially leading to higher exposure rates. These discrepancies highlight the complexity of T. equi epidemiology and suggest that local environmental factors, study design, and population characteristics could account for differences in findings across studies.
Similarly, for samples from Jeddah, a gender-related influence on T. equi prevalence may be present, even though the female horses exhibit a higher infection rate than males when evaluated by both microscopic and ELISA methods; the chi-squared test yielded a non-significant p-value (p = 0.1659), indicating no statistically significant association between gender and T. equi prevalence using the microscopic detection method. This suggests that while a trend may exist, it lacks statistical support, reinforcing the limitations of relying on microscopic evaluation alone for gender-based differences in parasitic burden [29,30]. However, similar to the microscopic method, the ELISA method also revealed a higher prevalence percentage in female horses, with the chi-squared test revealing a borderline p-value (p = 0.0995), suggesting non-statistical significance. The higher sensitivity of ELISA compared to microscopy likely contributes to this result, as it may detect latent or chronic infections that go undetected microscopically [31]. The borderline significance in this study could be attributed to biological or immunological differences between genders, as some studies suggest that females may be more susceptible to parasitic infections due to hormonal influences or differences in immune responses [32,33]. The implications of these findings are critical for understanding T. equi transmission dynamics and host susceptibility.
The higher infection rates in female horses may suggest either behavioral differences or physiological susceptibilities, possibly due to hormonal cycles or stress factors that may compromise immunity [34]. However, given the non-significant p-values, more research with larger sample sizes is necessary to draw firm conclusions. These results highlight the importance of using both ELISA and microscopic methods to comprehensively assess T. equi prevalence, especially considering ELISA with higher detection of subclinical or chronic infections [6]. Previous studies have reported conflicting findings regarding gender differences in T. equi prevalence. Some research aligns with the microscopic findings in this study, showing no significant association between gender and parasitic burden [35]. However, other studies have suggested a higher prevalence in female horses, potentially due to immunological factors or hormonal cycles affecting susceptibility to parasitic infections, which aligns with the results observed with the ELISA method in this study [36,37]. These mixed findings underscore the complexity of parasitic infections and the need for multi-method diagnostic approaches to capture a complete picture of infection rates.

4.2. Age Influence on the Prevalence of Theileria equi in Horses

The lack of a significant association between age groups in this study for both microscopic and ELISA methods in Taif and the microscopic method in Jeddah suggests that while the methods (microscopic and ELISA) may generally follow consistent trends in detecting T. equi prevalence across age groups, they may differ slightly in terms of sensitivity [34]. This highlights the precision of the methods and the ability to show significant associations with certain variables, such as age difference [38,39]. However, ELISA showed more sensitivity due to the significant association between prevalence and age when using this method for samples from Jeddah. Aziz and Al-Barwary [17] reported similar findings in their epidemiological study of Equine Piroplasmosis (T. equi and B. caballi) via microscopic examinations and ELISA methods. They established an association between age and T. equi infection in horses using the aforementioned methods. This further supports this finding, demonstrating that the ELISA method is particularly effective at identifying age-related trends in T. equi infection. The microscopic method might not be as sensitive in detecting age-related patterns in T. equi infection as the ELISA method, as it revealed a non-significant association between prevalence and age in both Taif and Jeddah.
The 100% prevalence recorded in some certain ages, such as in horses aged 2.5 and 13 years in Jeddah, implies that horses in particular age groups may be more or less susceptible to T. equi infection [40], and this aligns with previous findings [41], where age was identified as a potential risk factor for T. equi. So, also, the 100% positive results in horses aged 1.5 and 4 years using the ELISA method for samples from Jeddah suggest that ELISA might have higher detection in younger age groups [42]. The discrepancy between the microscopic and ELISA methods could be due to differences in their detection mechanisms, with ELISA possibly being more sensitive to antibodies [43]. In contrast, the microscopic method detects the parasite directly. In addition, the reason for the discrepancy between the two methods could lie in the nature of T. equi infection [44].
It is important to note that the microscopic method identifies active infections by visually detecting the parasite, while ELISA, on the other hand, detects antibodies, which may not be as tightly linked to the current infection status but to past exposure [45]. Previous findings have demonstrated similar discrepancies, where microscopic methods were found to be less sensitive in detecting the presence of T. equi in acute infections, while ELISA has higher detection for chronic or past infections considering antibodies [6,46]. This underscores the need to use multiple diagnostic methods to understand T. equi prevalence comprehensively. The implications of these findings are critical for disease management and control strategies. Since the ELISA method shows a stronger association between age and T. equi prevalence, it might be preferred in age-related epidemiological studies or in determining the prevalence of active infections.

4.3. Relationship Between Theileria equi in Male and Female Horses Using Microscopic and ELISA Diagnostic Tests

The Principal Component Analysis (PCA) highlights the relationship between Theileria equi infections in male and female horses and two diagnostic methods, microscopy and ELISA. The 96.0% of the total variation determining this relationship indicates a strong relationship between the presence of T. equi in the two genders of horses. However, the positive relationship between the ELISA method and T. equi in male horses suggested that the ELISA method is more reliable than the microscopic method in detecting T. equi, especially in male horses, perhaps due to lower parasitemia or differences in immune response between the two genders [17].
Similarly, the positive relationship between the microscopic diagnostic method and the prevalence of T. equi in female horses may be due to higher prevalence in females than males [22]. The higher-percentage prevalence might have caused less difficulty in detection, even though the microscopic method might not be more sensitive than the ELISA diagnostic method [47]. The implications of these results highlight the importance of selecting appropriate diagnostic tools based on the horse’s gender [25]. Although reliance on ELISA and microscopic methods appears to be effective for the two genders, this finding could influence veterinary diagnostic protocols, where female horses may receive routine screening through microscopy, while male horses may require more sensitive diagnostic methods such as ELISA [48]. Previous studies have similarly reported variability in diagnostic accuracy among different horse genders, with female horses often showing higher susceptibility to piroplasmosis infections [4,49]. This result aligns with research by Dias et al. [50], who noted that gender susceptibility could influence diagnostic outcomes, especially in high-prevalence areas. Our findings align with this observation and underscore the importance of individualized diagnostic protocols based on gender.

5. Conclusions

Our results reveal that there was no significant correlation between T. equi infection detection and horse gender using both microscopic examination and the ELISA technique.
However, when considering age, a significant correlation was observed only in Jeddah, where younger horses showed higher parasite detection rates using the ELISA technique.
The discrepancies between microscopic examination and ELISA can be attributed to their differences in detection capabilities; while microscopy identifies only active infection, ELISA can detect both current and past infections.
Therefore, broader studies with larger sample sizes, expanded geographic coverage and more advanced diagnostic techniques are needed to further investigate the association of age, gender and location with susceptibility to T. equi infection.

Author Contributions

Conceptualisation, M.O.A., M.E.A. and N.T.Z.; methodology, M.O.A., M.E.A. and N.T.Z.; software, M.O.A.; validation, M.O.A., M.E.A. and N.T.Z.; formal analysis, M.O.A.; investigation, M.O.A., M.E.A. and N.T.Z.; resources, M.O.A., M.E.A. and N.T.Z.; data curation, M.O.A.; writing—original draft preparation, M.O.A., M.E.A. and N.T.Z.; writing—review and editing, M.O.A., M.E.A. and N.T.Z.; visualisation, M.O.A., M.E.A. and N.T.Z.; supervision, M.O.A. and N.T.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was approved by the ethical research committee of the Faculty of Medicine at King Abdulaziz University under the reference number (8–25) Intervention (Animal Study).

Informed Consent Statement

Not applicable.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Acknowledgments

The authors acknowledge with thanks, Mohammed Sayed Mohammed, Layla Abdullah Alshehri, Shaker Safar Althobaiti and Adi ALMohimeed from Jeddah Seaport Lab, Ministry of Environment Water & Agriculture for providing support during analysis in the laboratory.

Conflicts of Interest

The authors declare no conflicts of interest.

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Parasitologia 05 00014 g001
Figure 1. Map of Saudi Arabia showing the sampling sites Jeddah and Taif.
Figure 1. Map of Saudi Arabia showing the sampling sites Jeddah and Taif.
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Figure 2. Relationship between Theileria equi in male and female horses using microscopic and ELISA diagnostic test. F = female, M = male, Mic = microscopic.
Figure 2. Relationship between Theileria equi in male and female horses using microscopic and ELISA diagnostic test. F = female, M = male, Mic = microscopic.
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Table 1. Blood and sera collected from horses in different localities in Makkah Province, Saudi Arabia, from 2022 to 2023.
Table 1. Blood and sera collected from horses in different localities in Makkah Province, Saudi Arabia, from 2022 to 2023.
Study AreaBloodSera
SmearcELISA
Al-Taif171171
Jeddah101101
Total272272
Table 2. Prevalence of Theileria equi in male and female horses from Taif city using microscopic and ELISA methods for determination.
Table 2. Prevalence of Theileria equi in male and female horses from Taif city using microscopic and ELISA methods for determination.
Microscopic Elisa
NegativePositiveTotalNegativePositiveTotal
Female54 (85.7)9 (14.3)6352 (82.5)11 (17.5)63
Male81 (75.0)27 (25.0)10898 (90.7)10 (9.3)108
χ22.748 2.412
Continuity Correction2.141 1.72
Likelihood Ratio2.872 2.334
Fisher’s Exact Test (Exact sig.)0.07 0.096
Table 3. Prevalence of Theileria equi in male and female horses from Jeddah city using microscopic and ELISA methods for determination.
Table 3. Prevalence of Theileria equi in male and female horses from Jeddah city using microscopic and ELISA methods for determination.
Microscopic Elisa
NegativePositiveTotalNegativePositiveTotal
Female51 (71.8)20 (28.2)7131 (43.7)40 (56.3)71
Male25 (83.3)5 (16.7)3018 (60.0)12 (40.0)30
χ21.498 2.254
Continuity Correction0.944 1.647
Likelihood Ratio1.58 2.2629
Fisher’s Exact Test (Exact sig.)0.1659 0.0995
Table 4. Prevalence of Theileria equi across different age groups of horses from Taif city using microscopic and ELISA methods for determination.
Table 4. Prevalence of Theileria equi across different age groups of horses from Taif city using microscopic and ELISA methods for determination.
Microscopic Elisa Total
Age (Years)NegativePositiveTotalNegativePositive
260 (75.9)19 (24.1)7972 (91.1)7 (8.9)79
335 (74.5)12 (25.5)4740 (85.1)7 (14.9)47
414 (82.4)3 (17.6)1713 (76.5)4 (23.5)17
513 (86.7)2 (13.3)1513 (86.7)2 (13.3)15
65 (100.0)0 (0.0)55 (100.0)0 (0.0)5
73 (100.0)0 (0.0)32 (66.7)1 (33.3)3
84 (100.0)0 (0.0)44 (100.0)0 (0.0)4
χ26.261 5.633
Fisher’s Exact Test (Exact sig.)0.395 0.465
Likelihood Ratio9.117 6.125
Table 5. Prevalence of Theileria equi across different age groups of horses from Jeddah city using microscopic and ELISA methods for determination.
Table 5. Prevalence of Theileria equi across different age groups of horses from Jeddah city using microscopic and ELISA methods for determination.
Microscopic Elisa
Age (Years)NegativePositiveTotalNegativePositiveTotal
17 (87.5)1 (12.5)83 (37.5)5 (62.5)8
1.51 (100.0)0 (0.0)10 (0.0)1 (100.0)1
23 (60.0)2 (40.0)53 (60.0)2 (40.0)5
2.50 (0.0)1 (100.0)11 (100.0)0 (0.0)1
32 (33.3)4 (66.7)62 (33.3)4 (66.7)6
42 (100.0)0 (0.0)20 (0.0)2 (100.0)2
53 (100.0)0 (0.0)31 (33.3)2 (66.7)3
66 (85.7)1 (14.3)72 (28.6)5 (71.4)7
79 (69.2)4 (30.8)137 (53.8)6 (46.2)13
812(85.7)2 (14.3)147 (50.0)7 (50.0)14
910 (90.9)1 (9.1)116 (54.5)5 (45.5)11
102 (40.0)3 (60.0)54 (80.0)1 (20.0)5
114 (100.0)0 (0.0)41 (25.0)3 (75.0)4
125 (100.0)0 (0.0)51 (20.0)4 (80.0)5
130 (0.0)2 (100.0)21 (50.0)1 (50.0)2
142 (66.7)1 (33.3)32 (66.7)1 (33.3)3
153 (100.0)0 (0.0)32 (66.7)1 (33.3)3
162 (100.0)0 (0.0)21 (50.0)1 (50.0)2
172 (66.7)1 (33.3)33 (100.0)0 (0.0)3
181 (33.3)2 (66.7)32 (66.7)1(33.3)3
χ215.678 31.966
Fisher’s Exact Test (Exact sig.)0.67862 0.032
Likelihood Ratio34.479 18.7581
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Albooq, M.E.; Aljahdali, M.O.; Zelai, N.T. Prevalence of Theileria equi in Horses from Taif and Jeddah, Saudi Arabia, Using Microscopic and ELISA Techniques. Parasitologia 2025, 5, 14. https://doi.org/10.3390/parasitologia5020014

AMA Style

Albooq ME, Aljahdali MO, Zelai NT. Prevalence of Theileria equi in Horses from Taif and Jeddah, Saudi Arabia, Using Microscopic and ELISA Techniques. Parasitologia. 2025; 5(2):14. https://doi.org/10.3390/parasitologia5020014

Chicago/Turabian Style

Albooq, Mona Ebraheem, Mohammed Othman Aljahdali, and Noha Talal Zelai. 2025. "Prevalence of Theileria equi in Horses from Taif and Jeddah, Saudi Arabia, Using Microscopic and ELISA Techniques" Parasitologia 5, no. 2: 14. https://doi.org/10.3390/parasitologia5020014

APA Style

Albooq, M. E., Aljahdali, M. O., & Zelai, N. T. (2025). Prevalence of Theileria equi in Horses from Taif and Jeddah, Saudi Arabia, Using Microscopic and ELISA Techniques. Parasitologia, 5(2), 14. https://doi.org/10.3390/parasitologia5020014

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