In this study, 1000 samples of Sawakni sheep (
Ovis aries), were examined during the period 1/1/2024 to 30/5/2024, from the livestock markets and various slaughterhouses in the city of Riyadh. Sheep are considered one of the most important components of livestock and a major source of meat in the Arabian Peninsula in general and in the Kingdom of Saudi Arabia in particular. However, they are infected with diseases that reduce their productivity. Coccidiosis is one of the most important diseases that may affect sheep
(Dudko et al., 2018). Infection with this parasite leads to severe diarrhea and a tear in the intestinal wall of infected sheep, which reduces their efficiency in digesting and absorbing food and, in turn, leads to disruption of the natural growth process and emaciation, which reduces the productivity and economic value of these sheep
(Akhtar et al., 2023). In view of the pathogenic importance of
Eimeria parasites, some survey studies were conducted in the Kingdom of Saudi Arabia on
Eimeria, which infects types of local sheep in general, without specifying the breeds of these sheep (
Kasim and Al-Shawa, 1985;
Toulah, 2007). Earlier to this
(Omer et al., 2020) reported that sheep in the city of Riyadh in the Kingdom of Saudi Arabia were infected with coccidian.
After examining all the study samples, infected with coccidia parasites of the genus
Eimeria the average total infection rate was 35.6% (Fig 2), the highest infection rate was in summer at 46.8% and the lowest infection rate was 26.4% in winter (Table 1).
In all five different species have been identified:
E. pallida, E. faurei, E. granulosa, E. parva and E. intricata where the infection was always mixed in all infected samples, the infection with
E. pallida was recorded by 7.70%, which was the highest percentage of the species in the infected samples, while the infection with
E. intricata by 0.30% was the lowest percentage of infection with this type (Table 2).
Based on the morphometric data, five
Eimeria species were detected in the feces of the examined sheep and identified as follows:
As for the first type
E. faurei,the sporulated oocysts were oval in shape and had a yellow-brown wall. These vesicles ranged in length from 30±0.5 (31-29) µm, while the width of the ovoid oocysts was 22±0.12 (21-23) µm and the ratio of length to width was (shape index) 1.40 (1.3-1.5) µm.
While examining the sporulated oocytes, it was found that there was no micropyle hole, micropyle cap, oocyst residuum, but there was presence of a polar granule. It was also found that each vesicle contains four 4-sporocysts and 2-sporozoites and has an ovoid shape, measuring 15±0.62 (15-17) µm in length and 7±0.81 (7-8) µm in width and the aspect ratio (shape index) was 2 (2-2.15) µm. The study proved that the sporocysts do not contain a steida body and contain the sporocyst residuum, as shown in (Fig 3A). The parasite
Eimeria faurei was described for the first time in sheep and goats (
Moussu and Marotol, 1902) and when comparing the results of this study with the results of the researchers (
H Hasan and Abed, 2012), as shown in Table 3. There were no significant differences when compared with the results of
Moussu and Marotol, (1902) that also showed the concordance of the description for the parasite
E. faurei.
As for the second type
E. intricata (Fig 3B), the sporulated oocysts are characterized as one of the largest types of
Eimeria that infect sheep. They are ellipsoidal in shape and have a rough brown wall that is striped. The measurements of these oocysts range in length from 45±0.83 (43-48) µm, while the width of the oocysts is 34±0.37 (34-35) µm. and the aspect ratio (shape index) is 1.3 (1.3-1.4) µm. Upon examining the sporulated oocytes, the presence of a micropyle, the presence of a micropyle cap and the absence of an oocyst residuum were noted. It was also found that each oocyte contains four sporocysts, which are diploid (2-sporozoites) and have an ovoid shape and their measurements range from 13±0.93 (13-16) µm in length and 8±0.75 (8-10) µm in width and the aspect ratio (shape index) was 1.6 (1.5-1.6) µm. The study showed that the sporocysts contain the steida body as well as the sporocyst residuum (Fig 3B). The parasite
Eimeria intricata was described for the first time in sheep (
Spiegl, 1925). The present study in regard to
E. intricata was in agreement with
Toulah, (2007), while there are some slight differences in the sizes of sporocysts in the current study compared with a study of
H Hasan and Abed, (2012).
The third type is
Eimeria parva (Fig 3C), the sporulated oocysts are spherical in shape with smooth bilayers, ranging in color from pale yellow to greenish yellow. The length of these oocytes ranged from 17±0.56 (13-19) µm, while the width of the oocytes was 16±0.75 (12-18) µm and the length-to-width ratio was 1 (1-1.1) µm. When examined the sporulated oocytes, it was found that there was no micropyle, no micropyle cap and no remnants of oocyst residuum. It was also found that each oocyte contains four sporocysts that are diploid (2-sporozoites) and have an ovoid shape, measuring 8±0.75 (8-10) µm in length and 6±0.1 (5-6) µm in width and the proportion of the length to width (shape index) was 1.4 (1.4-1.6) µm. The study showed that sporocysts contain a small steida body, as well as sporocyst residuum as indicated in Fig 3C. It was described for the first time in sheep by
(Kotlan et al., 1929). In the present study, it was confirmed that Al-Sawakni sheep in Saudi Arabia were infected with this parasite which matches with the description of the parasite
E. parva in many studies
(Dittmar et al., 2010; H Hasan and Abed, 2012).
As for the fourth type
Eimeria granulosa (Fig 3D), the sporulated oocysts are ovoid and have a yellow, transparent wall. The length of these oocysts ranged from 30±0.18 (29-31) µm, while the width of the oocysts was 20±0.31 (19-21) µm and the ratio of length to width (shape index) was 1.4 (1.4-1.5) µm. When examining the sporulated oocysts, it was revealed that there was a micropyle, the presence of a micropyle cap and the absence of an oocyst residuum. It was also found that each oocyst contains four sporocysts that are diploid (2-sporozoites) and have an ovoid shape, measuring 11±0.93 (11-12) µm in length and 6±0.93 (6-7) µm in diameter. The width, aspect ratio (shape index) was 1.7(1.7-1.75) µm. The study showed that sporocysts contain the steida body as well as the sporocyst’s residuum. The parasite
Eimeria granulosa was described for the first time by
Christensen, (1938) in sheep and in this study, it was proven that Al-Sawakni sheep in Riyadh, Saudi Arabia, were infected with this
E. granulosa. Some slight differences in oocyst sizes were found between the present study (Table 3) and reports by
Dittmar et al., (2010) and
H Hassan and Abed, (2012).
The fifth species is
Eimeria pallida (Fig 3E), where, the sporulated oocysts are oval and have a yellow-green wall. The length of these oocysts ranges from 17±0.5 (14-19) µm, while the oocytes are 13±0.50 (11-14) µm wide and the aspect ratio is 1.3.(1.2-1.4) µm. When examining the sporulated oocysts, it was found that there was no micropyle, no micropyle cap and no oocyst residuum. It was also found that each oocyst contains four sporocysts that are diploid (2-sporozoites) and have an oval shape, measuring 6±0.75 (6-8) µm in length and 4±0.1(3-6) µm in width and the aspect ratio (shape index) was 1.6(1.6-1.75) µm. The study proved that the sporocysts contain the solid body as well as the remaining sporocysts. The parasite
Eimeria pallida, was described in sheep for the first time by
Christensen, (1938) which is in agreement with the present study where this parasite was seen in Al-Sawakni sheep. which again agrees with the study of
(Dittmar et al., 2010; H Hasan and Abed, 2012). The current study recorded a total infection rate with
Eimeria parasites that reached 35.6% in the Sawakni sheep in the city of Riyadh, where the highest infection rate was in summer at 46.8% and the lowest infection rate in winter was 26.4%, the infection was mixed with more than one type of
Eimeria in all infected samples. It was noted in this study that there is a decrease in the infection rate in the winter season and the temperature may reach below zero degrees Celsius at times, in contrast to the summer, which makes the sporulation process impossible on the ground (
Parker and Jones, 1990).
