Epidemiology of Eimeria infections in sheep raised extensively in a semiarid region of Brazil

Identification of sheep eimerian parasites, Eimeria crandallis and Eimeria faurei, employing microscopic and molecular tools

Coccidiosis, caused by apicomplexan Eimeria species, is a protozoan disease that affects various species of wild and domestic animals. However, data available on Eimeria diversity in ruminants in Saudi Arabia is meagre. Therefore, this study was designed to investigate some eimerian parasites infecting sheep (Sawakni and Harrie breeds) using microscopy and molecular methods for the first time in Saudi Arabia. Twenty-four fecal samples were collected from sheep farms. Based on the floatation technique, eimerian oocysts were observed in 8 of the 24 (33.33%) fecal samples. The coccidian-positive samples were subjected to fecal culture in a shallow layer of 2.5% potassium dichromate (K2 Cr2 O7 ). Detected eimerian oocysts were described micromorphometrically as the basis for traditional oocyst identification. Morphologically, the sporulated oocysts were similar to those of sheep eimerian parasies; Eimeria faurei and Eimeria crandallis. PCR products from the two eimerian species detected from Sawakni and Harrie breeds were sequenced and were found to be distinct from each other with mutations at five positions. One of them clustered with E. crandallis with 99.8%-100% identity with sequences available in GenBank. E. crandallis was obtained from two Sawakni sheep and two Harrie sheep. The other sequences grouped with E. faurei with 99.8% identity with the only sequences available in GenBank. E. crandallis was detected from both Sawakni and Harrie breeds whereas E. faurei was detected only from Sawakni sheep. The findings of this study have implications for the importance of morphometric identification with advanced molecular tools to confirm the identities of sheep Eimeria species and to address the taxonomic study of this eimeriid parasite at the species level.

A questionnaire-based survey in Spain provides relevant information to improve the control of ovine coccidiosis

Ovine coccidiosis is a widespread intestinal parasitic disease caused by Eimeria spp. Lambs are infected by the ingestion of sporulated oocysts, experiencing diarrhea and low growth rates. Control should be based on measures to reduce infection pressure and stress on the animals as well as on appropriate diagnosis and strategic treatment. To obtain information on how control measures are implemented in the ovine sector in Spain, a questionnaire-based survey was completed in 2022 by 154 veterinarians and 173 farmers working in this sector. Coccidiosis was highlighted as a relevant disease by 34% of the respondents. The period of greatest risk seemed to differ between production systems, being mainly early after weaning (7-15 days after weaning) in meat flocks and feedlots and later (1-2 months after weaning) in dairy flocks. The absence of cleaning and disinfection measures was identified as a risk factor by 51% of the veterinarians, with 22% mentioning overcrowding of animals and 22% indicating that coccidiosis has more incidence in flocks with large number of animals. The use of laboratory diagnosis methods (fecal oocyst count) was unusual in 70 and 84% of the veterinarians and farmers, respectively. Regarding control, dairy flocks usually housed a larger number of animals under intensive conditions, and they implemented more frequently control measures for coccidiosis than meat flocks. Anticoccidial drugs were used in 79% of the flocks, and in 74-82% of them, they were applied based on clinical criteria. Comparing protocols for anticoccidial treatment among different production systems, in meat flocks, anticoccidial drugs were applied more frequently when clinical signs were observed, and coccidiostats were used for less than 28 days compared to dairy flocks. These results highlight the need for improvement in the use of anticoccidial treatments adjusted to the new regulatory framework in the EU, which in turn will rationalize the use of antimicrobial compounds and may help to mitigate the impact of coccidiosis in flocks.

Conservation agriculture has no significant impact on sheep digestive parasitism

Conservation agriculture (CONS A) is a sustainable agriculture system based on crop rotation with no tillage. It has various environmental advantages compared to conventional agriculture (CONV A): decreased water evaporation, erosion, and CO2 emissions. In this first study of its kind, we aim to evaluate the impact of this type of agriculture on sheep gastrointestinal parasites. Two lamb groups aged between 5 and 10 months were randomly included to graze separately on CONS A and CONV A pastures. Each group was composed of two batches of three lambs, and these were followed up for two rearing months. Liveweight, hematological parameter variation, and digestive parasites were studied. At the end of the study period, lambs were slaughtered the carcass yield was determined, and a helminthological autopsy was performed on the digestive tracts of the animals to estimate different parasitological indicators. There was no difference between lambs reared on CONS A and those reared on CONV A for all parasite indicators (infestation intensity, abundance, and prevalence). The same trend was also obtained for hematological parameters, liveweight evolution, and carcass yield. These results prove that there is no impact of CONS A on the sheep's digestive parasitism. Further studies are needed to support these findings on larger animal samples and to investigate the impact of conservation agriculture on other parasite species. Similar studies could also be conducted on ruminant species.

Ovine coccidiosis and associated risk factors in Minya, Egypt

Background

Coccidiosis is a potential protozoal disease of economic importance in sheep worldwide. The current study aimed to detect the prevalence of ovine coccidiosis and identification of the recovered species in Minya, Egypt. Three hundred and fifty sheep from Minia, Egypt, were coprologically examined for the occurrence of Eimeria species oocysts by using the standard floatation technique.

Results

Oocysts were detected in 180 (51.43%) animals. Mixed infection was recorded in 37.14% (130/350) and single infection was revealed in 14.29% (50/350) sheep. The prevalence of coccidiosis was significantly higher in young sheep. Fourteen Eimeria species were detected; Eimeria bakuensis, E. webybridgensis, E. ahusta, E. intricata, E. granulosa, E. faurei, E. ninakohlyakim-ovae, Eimeria coitae-like, E. parva, E. pallida, E. marsica, E. crandallis, E. ovinoidalis and E. arloingi. The most predominant Eimeria species was Eimeria parva (14.57%; 51/350) followed by E. ovinoidalis (14.0%; 49/350), E. granulosa (8.29%; 29/350), E. bakuensis (7.14%; 25/350), E. intricata (5.43%; 19/350), E. faurei and E. webybridgensis (4.86%; 17/350 each), E. pallida (4.0%; 14/350), E. ninakohlyakim-ovae (3.71%; 13/350), E. crandallis and E. ahsata (3.43%; 12/350 each), E. marsica and E. arloingi (1.71%; 6/350 each). The least abundant species was E. coitae-like (1.14%; 4/350).

Conclusion

Fourteen Eimeria species were recovered from sheep in Minya, Egypt; Eimeria bakuensis, E. webybridgensis, E. ahusta, E. intricata, E. granulosa, E. faurei, E. ninakohlyakim-ovae, Eimeria coitae-like, E. parva, E. pallida, E. marsica, E. crandallis, E. ovinoidalis and E. arloingi. Eimeria parva was the most common while E. coitae-like was the least. To the best of our knowledge, this is the first report for the occurrence of E. coitae-like in sheep in Egypt. Prevention and effective control programs should be strictly followed to avoid economic losses resulted from the coccidian infection.

Immunoprotection against mixed Eimeria spp. infections in goat kids induced by X-irradiated oocysts

Strategies to control goat coccidiosis traditionally rely on the use of management practices combined with anticoccidial treatments, and limited effort has been made, so far, to address immunological control of caprine Eimeria infections. Previously, we showed that monospecific immunization with X-Rad-attenuated Eimeria ninakohlyakimovae oocysts induced considerable immunoprotection upon challenge. In the present study, we conducted a similar vaccination trial but using a mixture of caprine Eimeria species typically present in natural infected goats. For immunization, sporulated oocysts were attenuated by X irradiation (20 kilorad). All infections were performed orally applying 10⁵ sporulated oocysts of mixed Eimeria spp. per animal. In total, 18 goat kids were grouped as follows: (G1) immunized + challenge infected; (G2) primary + challenge infected; (G3) challenge infection control; and (G4) non-immunized/non-infected control. Overall, goat kids infected with attenuated oocysts (= immunized) shed less oocysts in the faeces and showed a lower degree of clinical coccidiosis than animals infected with non-attenuated oocysts. Animals of both challenge groups (G1 and G2) showed partial immunoprotection upon reinfection when compared to challenge infection control (G3). However, the degree of immunoprotection was less pronounced than recently reported for monospecific vaccination against Eimeria ninakohlyakimovae, most probably due to the complexity of the pathogenesis and related immune responses against mixed Eimeria spp. infections. Nevertheless, the data of the present study demonstrate that immunization with attenuated Eimeria spp. oocysts may be worth pursuing as a strategy to control goat coccidiosis.

Prevalence and risk factors of Eimeria spp. natural infection in sheep from northern Paraná, Brazil

The present study aimed to perform an epidemiological and morphological identification of Eimeria infection in sheep in Brazil. Fecal samples from sheep were collected from 20 farms in northern Paraná, Brazil. An epidemiological questionnaire was used to evaluate the risk factors. Fecal samples containing oocysts per gram of feces (OoPG) ≥1000 were subjected to the modified Willis-Mollay method to perform oocyst identification. Sporulated oocysts were observed microscopically for morphological identification. A total of 807 fecal samples were collected. Based on the morphological characteristics of the sporulated oocysts, 10 species of Eimeria were identified, with main species observed: Eimeira ovinoidalis (98.1%), Eimeria crandallis (87.6%), Eimeria parva (79.1%), and Eimeria bakuensis (60.8%). Only 2.6% (7/268) of the sheep were infected with a single species, 4.8% (13/268) contained two different species, and 92.5% (248/268) were infected with three or more species. The analysis of risk factors showed that an intensive rearing, no rotation of pasture, dirt, and slatted floors, and age up to 12 months were associated with infection. This study showed a high prevalence of Eimeria natural infection in sheep from northern Paraná, Brazil. Furthermore, based on the risk factors, good management and hygiene practices must be employed to avoid infection.

Determinants of Eimeria and Campylobacter infection dynamics in UK domestic sheep: the role of co-infection

Coccidiosis caused by Eimeria species is a well-recognized disease of livestock. Enteric Eimeria infections are common, but disease usually only manifests when infection intensity is abnormally high. Campylobacter species are important zoonotic enteric bacterial pathogens for which livestock are important reservoir hosts. The diversity and epidemiology of ovine Eimeria and Campylobacter infections on two farms in north-western England were explored through a 24-month survey of shedding in sheep feces. Most animals were infected with at least one of 10 different Eimeria species, among which E. bakuensis and E. ovinoidalis were most common. An animal's age and the season of sampling were associated with the probability and intensity of Eimeria infection. Season of sampling was also associated with the probability of Campylobacter infection. Interestingly, higher intensities of Eimeria infections were significantly more common in animals not co-infected with Campylobacter. We explored the determinants of E. bakuensis and E. ovinoidalis infections, observing that being infected with either significantly increased the likelihood of infection with the other. The prevalence of E. ovinoidalis infections was significantly lower in sheep infected with Campylobacter. Recognition that co-infectors shape the dynamics of parasite infection is relevant to the design of effective infection control programmes.

Prevalence and risk factors associated with infection by Eimeria spp. in goats and sheep in Northeastern Brazil

Eimeria spp. infections lead to acute or chronic intestinal disorders in small ruminants, being responsible for important economic losses worldwide. The aim of this study was to assess the risk factors associated with Eimeria spp. infection in small ruminants of the microregion of Garanhuns, state of Pernambuco, Northeastern Brazil. Fecal samples (n = 822) were obtained from goats (n = 414) and sheep (n = 408) and evaluated by the modified Gordon and Whitlock technique. Risk factors were assessed through univariate analysis and logistical regression. Oocysts of Eimeria species were detected in 62.9% (517/822) of the animals, with 77.8% (322/414) in goats and 47.8% (195/408) in sheep. For goats, the herd size (OR = 5.52), rearing system (OR = 1.57), feeding place (OR = 2.60), absence of mineral salt in the diet (OR = 2.54), flooring type (OR = 2.83) and periodicity of cleaning (OR = 5.39) were considered risk factors. Conversely, for sheep only the herd size (OR = 3.16) and rearing system (OR = 2.45) were important factors associated with infection by Eimeria spp. Data herein obtained brings meaningful information on the epidemiology of coccidiosis in small ruminants in Northeastern Brazil. The knowledge of these risk factors is useful to contribute to the development of preventive measures, thereby, reducing the economic impact caused by these protozoa in small ruminant production.

First record of clinical coccidiosis (Eimeria ovinoidalis) in adult sheep from northwestern Argentina

Coccidiosis of sheep is an intestinal infection caused by protozoa of the genus Eimeria. An outbreak of the disease in adult sheep from Salta province, northwestern Argentina, was studied to establish its clinical, epidemiological, pathological and etiological aspects. The affected animals were part of a flock of 20 sheep brought from Formosa province about 10 days before. Most sheep (80% incidence) showed hemorrhagic diarrhea, dehydration and loss of body condition; six of them died and two that became permanently recumbent were euthanized. Three necropsied sheep showed mild mesenteric lymphadenomegaly, diffuse proliferative enteritis in the small and large intestines, and mucosal thickening. Histopathological studies exhibited diffuse proliferative enteritis and presence of structures compatible with intracellular coccidia at different stages of development. Parasitological studies (n = 12) resulted in an average of 16,636.6 (± 15,266.8) Eimeria oocysts per gram of feces (range 1680-46,400). Taxonomy of Eimeria species based on analysis of sporulated oocysts derived from 4 fecal samples (n = 100 oocyst per sample) showed, on average, a high prevalence of E. ovinoidalis (61.5%), followed by E. parva (27.2%), and lower proportions of E. crandallis (5.3%), E. ahsata (3.2%) and E. intricata (2.8%). Clinical and pathological findings confirmed the diagnosis of coccidiosis in the affected sheep; parasitological results showed that E. ovinoidalis was the main species responsible for the clinical signs. Clinical coccidiosis is considered unusual in adult sheep, but the present case shows that under favorable environmental and/or management conditions, this infection may be highly deleterious for adult sheep.

Morphological characterization and first molecular identification of the eleven Eimeria species that infect sheep from Mexico

Within livestock production, enteric diseases play an important role, since they cause severe economic losses due to mortality, growth depression, and reduction in the conversion rate. Coccidiosis caused by Eimeria spp. is a parasitic disease of high morbidity that affects various animal species, including sheep. In sheep, eleven species of Eimeria have been identified mainly through microscopical identification of the oocysts; however, this technique has certain limitations that make it difficult to identify the different Eimeria species. The objective of the present study was to morphologically identify the eleven species of Eimeria that infect sheep in the southeastern region of the State of Mexico, as well as obtain the partial sequence of the ITS-1 rRNA region of each species and analyze it phylogenetically. A total of 412 samples were collected from the 13 municipalities that comprise the region I of the State of Mexico, out of which, 40 had approximately 80% of a single Eimeria species. Among these, the eleven Eimeria species reported in sheep were identified. The phylogenetic analysis showed that the species reported in this study are associated with those reported in rabbits, bovines, and birds. It is suggested that the phylogenetic division of sheep in two clades may be associated with the presence or absence of the residual body. It is proposed that the present methodology can be used effectively for diagnosis and to obtain information about the epidemiology of ovine coccidial infection. The results obtained in this study constitute the first report of the ITS-1 region of the eleven Eimeria species that infect sheep worldwide.