Molecular prevalence and preponderance of Eimeria spp. among chickens in Tamil Nadu, India

Molecular phylogenetic analysis and seasonal dynamics of Eimeria species infecting broilers of Kashmir, India

Globally, the poultry industry is seriously threatened by coccidiosis caused by various species of Eimeria. This protozoan parasite inhabits the epithelial lining of the gastrointestinal tract of poultry globally and can cause serious clinical disease. The present study was carried out on poultry farms located in various regions of Kashmir, India, to investigate the prevalence and phylogenetic relationships of Eimeria species affecting broiler chickens. Over a period of one year, fecal samples were collected from 60 poultry farms in Kashmir and morphological and molecular techniques were employed for Eimeria species identification. Results revealed a high prevalence of coccidiosis, with 58.3% (35/60) of farms positive for Eimeria. The most prevalent species were E. tenella (31/35, 88.6%) followed by E. acervulina (25/35, 71.4%), E. maxima (19/35, 54.3%), E. mitis (18/35, 51.4%), and E. necatrix (9/35, 25.7%). Seasonal variation in prevalence was also observed, with the highest rates in autumn (86.7%) and summer (66.7%). Additionally, younger birds (3-4 weeks) exhibited higher infection rates (85.7%) compared to older birds (57.9%) (5-6 weeks). Mixed infection was found in 94.2% (33/35) of positive farms. Phylogenetic analysis using ITS1 sequences confirmed species clustering and revealed evolutionary relationships among Eimeria species. E. tenella and E. necatrix formed a distinct clade, while E. acervulina formed another. The study underscores the importance of molecular techniques in accurate species identification and provides valuable insights into the epidemiology of coccidiosis in poultry in Kashmir. Effective control strategies, including vaccination and improved management practices, are necessary to mitigate the economic losses associated with this widespread poultry disease.

The global prevalence and associated risk factors of Eimeria infection in domestic chickens: A systematic review and meta-analysis

BACKGROUND

Eimeria is a protozoan parasite that affects poultry, particularly chickens, causing a disease known as coccidiosis. This disease imposes substantial significant economic challenges to the poultry sector.

OBJECTIVES

The current study aimed to estimate the global prevalence and associated risk factors of Eimeria in domestic chickens.

METHODS

Multiple databases (Scopus, PubMed, ProQuest, Web of Science and Google Scholar) were searched for articles published until June 2023. The pooled prevalence was estimated using a random-effects model with a 95% confidence interval. The statistical analysis was conducted using meta packages in R version (3.6.1).

RESULTS

In total, 41 articles fulfilled the eligibility criteria. The global pooled prevalence was 44.3% (36.9%-51.8%) with Eimeria tenella (38.7%, 30.1%-47.7%) as the most prevalent species. The highest pooled prevalence was related to the Western Pacific Region (80.5%, 72.6%-87.3%) and urban areas (44.4%, 36.5%-52.6%). Moreover, areas with humid subtropical climates represent the highest overall prevalence (75.8%, 46.6%-95.9%).

CONCLUSION

The necessity for robust and innovative strategies for preventing and managing this disease cannot be overstated. Addressing Eimeria impact is crucial not only for safeguarding poultry health but also for sustaining the economic viability of the poultry industry.

Prevalence of Avian coccidiosis in India: a review

Coccidiosis stands as a highly significant and economically impactful parasitic ailment in poultry, attributed to the intracellular parasite belonging to the genus Eimeria. This affliction poses considerable financial challenges to the poultry industry and is prevalent in most tropical and subtropical regions globally. The primary mode of transmission is through the fecal-oral route, predominantly affecting young chicks and chickens within intensive rearing systems. There are nine distinct Eimeria species that affect poultry, manifesting primarily in caecal and intestinal forms. Diagnosis typically relies on examining fecal samples for oocysts and post-mortem lesions. Molecular techniques are employed for both diagnosis and control of poultry coccidiosis. To combat the disease, anticoccidials are consistently incorporated into feed and water, but this practice may contribute to the emergence of resistant strains. Various vaccines, including live or live attenuated options, are currently in use for coccidiosis prevention.

Identification of Eimeria acervulina (Apicomplexa: Eimeriidae) infecting the broiler chicken Gallus gallus domesticus through morphology and molecular analyses

Coccidiosis is an intestinal protozoan disease that affects the poultry industry worldwide. The severity of this disease varies depending on the identity of the infectious agents. Therefore, this study was carried out to identify the Eimeria species that affect broiler chickens, Gallus gallus domesticus, through morphological and molecular phylogenetic analyses. Twenty-five faecal samples were collected from the broiler chickens in a commercial poultry farm in Riyadh (Saudi Arabia). Using the floatation technique, faeces were examined microscopically for the Eimeria occurrence. Identification of Eimeria species was performed based on morphological criteria and molecular tools (DNA amplification for the partial small subunit ribosomal RNA (18S rRNA), internal transcribed spacer (ITS)-1, and mitochondrial cytochrome c oxidase I (COI) genes. In this study, 32% (8 out of 25) of collected samples were found to be positive for coccidiosis. After sporulation in potassium dichromate (K2Cr2O7), the sporulated oocysts were observed as ovoid and measured 18.37-23.19 µm (19.87) long and 15.07-18.67 µm (16.46) wide, with the anterior location of a polar granule and absence of micropyle. These Eimeria oocysts were assumed to size and shape characteristics of Eimeria acervulina. Molecular analysis was conducted on the sequences of the polymerase chain reaction products from the three genes studied (18S rRNA, ITS-1, and COI). At the three genes, results showed that the resultant sequences clustered with E. acervulina from different regions confirming morphological description. This study highlighted the importance of molecular techniques to detect avian Eimeria species more than the traditional morphology-based tool to optimise the appropriate anticoccidial strategies for long-term control in the studied area.

Prevalence of Eimeria Species, Detected by ITS1-PCR Immobilized on FTA Cards, in Future Laying Hens and Breeding Hens in Six Provinces in Northeastern Algeria

PURPOSE

Avian coccidiosis is an important and widely distributed disease that affects global agricultural economies through losses. In Algeria, there is limited epidemiological and ecological knowledge about this disease and this hinders implementation of control strategies. A recent study, in Algeria, demonstrated a high prevalence and diversity of Eimeria species in broiler chickens. However, very little is known about the Eimeria species that exist on chicken farms raised on the floor and older than broiler chickens (for example, future laying hens and breeding hens) in Algeria.

METHODS

Samples were collected from 32 poultry farms located in 6 northeastern Algerian provinces (Algiers, Batna, Bejaia, Bordj Bou Arréridj, Jijel, Mila). These included 22 pre-laying pullet farms, with hens aged between 11 and 17 weeks, and 10 breeding hen farms with older hens (over 20 weeks). FTA cards were used to capture DNA and internal transcribed Spacer 1 PCR (ITS1-PCR) was used to determine the prevalence and composition of Eimeria species in the chickens.

RESULTS

This showed the presence of six species of Eimeria with a diverse prevalence range. Eimeria necatrix (63%) was the most common species, followed by E. maxima (53%), E. tenella (31%), E. brunetti (19%), E. acervulina and E. mitis (both 0.3%). Eimeria praecox was absent. Eimeria infection affected all farms studied where co-infections by different Eimeria species (63%) were more frequent than single infections (38%). The number of oocyts, per ml of enriched oocyst suspension was higher in breeding hen farms compared to pre-laying pullet farms.

CONCLUSION

This study, taken alongside a previous study involving broiler farms, demonstrated that the infection with this parasite is a significant problem in Algeria.

First report of Eimeria myoxi in the garden dormouse (Eliomys quercinus Linnaeus, 1766) from Doñana Natural Area (Andalusia, SW Spain)

This work reports for the first time the presence and molecular characterization of Eimeria myoxi in the garden dormouse (Eliomys quercinus) from the Doñana Natural Area (Andalusia, SW Spain). Fresh faecal samples were collected from a total of 28 garden dormice, which were caught following current guidelines for the ethical use of animals in research, and processing by a standard flotation technique with saturated saline solution. Then, wet drops were examined microscopically, and the number of oocysts was semi-quantified. Eimeria oocysts were observed in 16 of the 28 (57.1%) faecal samples, showing most of them a very low number of oocysts (≤1 oocyst per microscopic field × 400). The unsporulated oocysts visualized in 16 faecal samples were subspherical and of length 19.2 ± 1.2 μm and width 17.4 ± 1.1 μm, being morphologically compatible with E. myoxi. This finding was supported by molecular analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, identifying the same species in 22 of the 28 (78.6%) dormice, including 15 samples in which oocyst size was compatible with E. myoxi. Moreover, the subsequent analyses of the apicoplast open reading frame 470 (ORF470) and the mitochondrial cytochrome c oxidase subunit I (COI) genes confirmed the molecular identification of the isolates as E. myoxi. The phylogeny analyses were consistent with previous phylogenetic studies and support the existence of three lineages of rodent-infecting Eimeria species.

Prevalence of Eimeria species, detected by ITS1-PCR, in broiler poultry farms located in seven provinces of northeastern Algeria

Coccidiosis is an important global chickens' disease which can cause serious economic losses in the poultry industry worldwide. Little is known about the extent of infection or diversity, of the causative agent Eimeria spp., in Algeria. A priority, therefore, is to determine the prevalence and species composition to inform strategies on treatments and control measures. Samples were collected from 187 broiler farms, located in 7 Northeastern Algerian provinces (Jijel, Constantine, Skikda, Mila, Setif, Batna, Bordj bou-Arreridj), and Internal Transcribed Spacer 1 PCR (ITS1-PCR) was used to determine the prevalence and composition of Eimeria species in chickens. The survey revealed the presence of all seven species of Eimeria at different prevalences (E. maxima (69%), E. acervulina (68.4%), E. necatrix (11.2%), E. tenella (8%), E. praecox (4.3%), E. mitis (2.1%), E. brunetti (2.1%). Multiple infections, with up to 4 different Eimeria species present on a single farm, were the most frequent situation in our samples (51.9% mixed infections versus 47.6% single infections). All farms revealed infected samples, and we conclude that this parasite is a significant problem in these provinces.

Epidemiological investigation and drug resistance of Eimeria species in Korean chicken farms

Background

Coccidiosis is a poultry disease that occurs worldwide and is caused by Eimeria species. The infection is associated with reduced feed efficiency, body weight gain, and egg production. This study aimed to investigate the current status of coccidiosis and anticoccidial resistance to anticoccidial drugs used as part of control strategies for this disease in Korean chicken farms.

Results

An overall prevalence of 75% (291/388) was found. Positive farms contained several Eimeria species (mean = 4.2). Of the positive samples, E. acervulina (98.6%), E. maxima (84.8%), and E. tenella (82.8%) were the most prevalent species. Compared with cage-fed chickens, broilers and native chickens reared in free-range management were more at risk of acquiring an Eimeria infection. Sensitivities to six anticoccidial drugs (clopidol, diclazuril, maduramycin, monensin, salinomycin, and toltrazuril) were tested using nine field samples. Compared with untreated healthy control chickens, the body weight gains of infected chickens and treated/infected chickens were significantly reduced in all groups. Fecal oocyst shedding was significantly reduced in four clopidol-treated/infected groups, three diclazuril-treated/infected groups, two toltrazuril-treated/infected groups, one monensin-treated/infected group, and one salinomycin-treated/infected group, compared with the respective untreated/infected control groups. Intestinal lesion scores were also reduced in three clopidol-treated/infected groups, one monensin-treated/infected group, and one toltrazuril-treated/infected group. However, an overall assessment using the anticoccidial index, percent optimum anticoccidial activity, relative oocyst production, and reduced lesion score index found that all field samples had strong resistance to all tested anticoccidial drugs.

Conclusion

The results of this large-scale epidemiological investigation and anticoccidial sensitivity testing showed a high prevalence of coccidiosis and the presence of severe drug resistant Eimeria species in the field. These findings will be useful for optimizing the control of coccidiosis in the poultry industry.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03369-3.

Study on the prevalence and genetic diversity of Eimeria species from broilers and free-range chickens in KwaZulu-Natal province, South Africa

This study was conducted from January to October 2018 with the objective to determine the prevalence and genetic diversity of Eimeria species in broiler and free-range chickens in KwaZulu-Natal province, South Africa. A total of 342 faecal samples were collected from 12 randomly selected healthy broiler chicken farms and 40 free-range chickens from 10 different locations. Faecal samples were screened for the presence of Eimeria oocysts using a standard flotation method. The species of Eimeria isolates were confirmed by amplification of the internal transcribed spacer 1 (ITS-1) partial region and sequences analysis. Among broiler and free-ranging chickens, 19 out of 41 pens (46.3%) and 25 out of 42 faecal samples (59.5%) were positive for Eimeria infection. Molecular detection revealed the following species: Eimeria maxima, Eimeria tenella, Eimeria acervulina, Eimeria brunetti and Eimeria mitis in all the samples screened. Similarly, polymerase chain reaction assays specific for three cryptic Eimeria operational taxonomic units were negative for all the samples. Phylogenetic analysis of the ITS-1 sequences supported species identity with the greatest variation detected for E. mitis. This study provides information on the range and identity of Eimeria species, and their genetic relatedness, circulating in commercially reared broilers and free-ranging chickens from different locations in KwaZulu-Natal province.

First molecular data on Eimeria truttae from brown trout (Salmo trutta)

The genus Eimeria comprises obligate intracellular protozoan parasites belonging to the phylum Apicomplexa. Members of this genus cause enteric disease in a wide range of vertebrate hosts, including fish, reptiles, birds, and mammals. A total of 157 species of Eimeria that parasitize fish have been described; however, molecular information regarding these piscine parasites is scarce. In the present study, Eimeria oocysts were detected in 189 of 613 (30.8%) gastrointestinal tracts of brown trout (Salmo trutta) captured in several rivers in Galicia (NW Spain). Measurements of the sporulated oocysts, sporocysts, and other morphological characteristics enabled identification of the oocysts as Eimeria truttae. By molecular analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, a single sequence of ~ 420 bp was obtained in 100 fish samples. After amplification of a ~ 1300-bp fragment of the same locus, two representative sequences that exhibited five nucleotide differences were obtained. Phylogenetic analysis grouped the samples within the piscine clade closest to Eimeria nemethi as they exhibited 96.7% similarity with this species. This study is the first to characterize E. truttae at the molecular level, thus helping to clarify the phylogenetic relationships between this and other Eimeria species isolated from fish and contributing further to the knowledge about this protozoan parasite.

Illumina Next Generation Sequencing for the Analysis of Eimeria Populations in Commercial Broilers and Indigenous Chickens

Eimeria species parasites can cause the enteric disease coccidiosis, most notably in chickens where the economic and welfare implications are significant. Seven Eimeria species are recognized to infect chickens, although understanding of their regional occurrence, abundance, and population structure remains limited. Reports of Eimeria circulating in chickens across much of the southern hemisphere with cryptic genotypes and the capacity to escape current anticoccidial vaccines have revealed unexpected levels of complexity. Consequently, it is important to supplement validated species-specific molecular diagnostics with new genus-level tools. Here, we report the application of Illumina MiSeq deep sequencing to partial 18S rDNA amplicons generated using Eimeria genus-specific primers from chicken caecal contents collected in India. Commercial Cobb400 broiler and indigenous Kadaknath type chickens were sampled under field conditions after co-rearing (mixed type farms, n = 150 chickens for each) or separate rearing (single type farms, n = 150 each). Comparison of MiSeq results with established Internal Transcribed Spacer (ITS) and Sequence Characterised Amplified Region (SCAR) quantitative PCR assays suggest greater sensitivity for the MiSeq approach. The caecal-dwelling Eimeria tenella and E. necatrix dominated each sample set, although all seven species which infect chickens were detected. Two of the three cryptic Eimeria genotypes were detected including OTU-X and OTU-Y, the most northern report for the latter to date. Low levels of DNA representing other Eimeria species were detected, possibly representing farm-level contamination with non-replicating oocysts or Eimeria DNA, or false positives, indicating a requirement for additional validation. Next generation deep amplicon sequencing offers a valuable resource for future Eimeria studies.

Prevalence of Eimeria species in domestic chickens in Anhui province, China

Prevalence studies can adequately assist in the design of prophylaxis strategies for disease control. Here, the prevalence of Eimeria species in chickens was investigated in Anhui province, China, from July to September 2016. A total of 171 samples were tested by microscopic examination and molecular methods. The prevalence of coccidiosis in Anhui province was found to be 87.75% (150/171). Eimeria tenella was the most prevalent species (80.67%, 121/150), and Eimeria necatrix, Eimeria mitis, Eimeria maxima, Eimeria brunetti and Eimeria acervulina were 68% (102/150), 55.33% (83/150), 54.67% (82/150), 44.67% (67/150) and 2.67% (4/150), respectively. Eimeria praecox was not detected at all. The most common combinations are E. tenella, E. maxima, E. necatrix, E. brunetti and E. mitis (26.67%, 40/150), followed by E. tenella, E. maxima and E. necatrix (19.33%, 29/150). Eimeria necatrix exhibited the highest participation in multiple infections. The results of the present study suggested that Eimeria infection is mixed, severe and widespread in chickens, Therefore, integrated strategies should be performed to prevent and control coccidial infection in chickens in Anhui province.

Eimeria species occurrence varies between geographic regions and poultry production systems and may influence parasite genetic diversity

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Multivariate analysis revealed comparable poultry clusters in north and south India.

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Eimeria species occurrence varied between system clusters.

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E. tenella occurrence across systems may underpin region-specific genetic diversity.

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E. necatrix was found to be more common in north than south India.

Coccidiosis is one of the biggest challenges faced by the global poultry industry. Recent studies have highlighted the ubiquitous distribution of all Eimeria species which can cause this disease in chickens, but intriguingly revealed a regional divide in genetic diversity and population structure for at least one species, Eimeria tenella. The drivers associated with such distinct geographic variation are unclear, but may impact on the occurrence and extent of resistance to anticoccidial drugs and future subunit vaccines. India is one of the largest poultry producers in the world and includes a transition between E. tenella populations defined by high and low genetic diversity. The aim of this study was to identify risk factors associated with the prevalence of Eimeria species defined by high and low pathogenicity in northern and southern states of India, and seek to understand factors which vary between the regions as possible drivers for differential genetic variation. Faecal samples and data relating to farm characteristics and management were collected from 107 farms from northern India and 133 farms from southern India. Faecal samples were analysed using microscopy and PCR to identify Eimeria occurrence. Multiple correspondence analysis was applied to transform correlated putative risk factors into a smaller number of synthetic uncorrelated factors. Hierarchical cluster analysis was used to identify poultry farm typologies, revealing three distinct clusters in the studied regions. The association between clusters and presence of Eimeria species was assessed by logistic regression. The study found that large-scale broiler farms in the north were at greatest risk of harbouring any Eimeria species and a larger proportion of such farms were positive for E. necatrix, the most pathogenic species. Comparison revealed a more even distribution for E. tenella across production systems in south India, but with a lower overall occurrence. Such a polarised region- and system-specific distribution may contribute to the different levels of genetic diversity observed previously in India and may influence parasite population structure across much of Asia and Africa. The findings of the study can be used to prioritise target farms to launch and optimise appropriate anticoccidial strategies for long-term control.

Genetic diversity within ITS-1 region of Eimeria species infecting chickens of north India

Coccidiosis, caused by apicomplexan parasites of the genus Eimeria, inflicts severe economic losses to the poultry industry around the globe. In the present study, ITS-1 based species specific nested PCR revealed prevalence of E. acervulina, E. brunetti, E. maxima, E. mitis, E. praecox, E. necatrix and E. tenella in 79.2%, 12.5%, 64.6%, 89.6%, 60.4%, 64.6% and 97.9% poultry farms of north India, respectively. The ITS-1 sequences of different Eimeria spp. from north India were generated and analyzed to establish their phylogenetic relationship. The sequence identity with available sequences ranged from 80 to 100% in E. tenella, 95 to 100% in E. acervulina, 64 to 97% in E. necatrix, 96 to 99% in E. brunetti and 97 to 98% in E. mitis. Only long ITS-1 sequences of E. maxima could be generated in the present study and it had 80-100% identity with published sequences. Two out of the four ITS-1 sequences of E. maxima had mismatches in the published nested primer sequences from Australia, while one sequence of E. necatrix had a mismatch near 3' end of both forward and reverse published nested primer sequences, warranting for the need of designing new set of degenerate primers for these two species of Eimeria. In the phylogenetic tree, all isolates of E. acervulina, E. brunetti, E. mitis, E. tenella and E. necatrix clustered in separate clades with high bootstrap value. E. maxima sequences of north Indian isolates grouped in a long form of E. maxima clade. Complete ITS-1 sequences of E. necatrix and E. mitis are reported for the first time from India. Further studies are required with more number of isolates to verify whether these differences are unique to geographical locations.

Prevalence of poultry coccidiosis in Jammu region of Jammu & Kashmir State

In this study prevalence of chicken coccidiosis in Jammu division were undertaken in both organized and backyard chickens during the year 2010-2011, with an overall prevalence of 39.58 % on examination of 720 faecal samples. Five Eimeria species were identified viz., E. tenella, E. necatrix, E. maxima, E. acervulina and E. mitis. E. tenella was the predominant species in both organized and unorganized farms. The highest prevalence percentage was found in July, 2011 (68.9 %) and the lowest percentage was found in May, 2011 (12.5 %). Coccidial prevalence was found to be 53.61 % in unorganized (backyard poultry birds) as compared to organized birds (25.55 %). Maximum positive cases of coccidian infection was found in monsoon season (60.55 %) and least in summer season (21.66 %). Birds of age 31-45 days showed more prevalence percentage (58.86 %). Higher oocysts count was recorded from July to September with a peak value (38973.00 ± 3075.6) in July and lowest (12914.00 ± 595.48) in the month of May.

Further characterisation of two Eimeria species (Eimeria quokka and Eimeria setonicis) in quokkas (Setonix brachyurus)

The identification and characterisation of novel Eimeria species has largely been based on sporulated oocyst and sporocyst morphology, the host species and the geographical range. Variation in the size and shape of Eimeria oocysts across their host range however, make the identification and characterisation of novel species using traditional methodologies alone problematic. The use of molecular markers and phylogenetic analysis has greatly advanced our ability to characterise Eimeria species and has recently been applied to understand evolutionary relationships among Eimeria species from Australian marsupials. In the present study, Eimeria species isolated from quokkas (Setonix brachyurus) captured from Two Peoples Bay, Bald Island and Rottnest Island, Western Australia, were morphologically identified as Eimeria quokka and Eimeria setonicis. Both Eimeria species were identified as being polymorphic in nature with regards to sporulated oocyst and sporocyst morphometrics. Phylogenetic analysis using 18S rRNA and COI (cytochrome c oxidase subunit 1) genes, grouped E. quokka and E. setonicis within the Eimeria marsupial clade together with Eimeria trichosuri from brushtail possums, Eimeria macropodis from tammar wallabies (Macropus eugenii) and several unidentified macropod Eimeria species from western grey kangaroos (Macropus fuliginosus). This study is the first to characterise E. quokka and E. setonicis by molecular analysis, enabling more extensive resolution of evolutionary relationships among marsupial-derived Eimeria species.

Prevalence and distribution of Eimeria species in broiler chicken farms of different capacities

We conducted a survey in broiler farms from Romania to establish prevalence and distribution of Eimeria species using single PCR assay. We found Eimeria spp. in 21 (91%) out of 23 flocks, and in 11 (92%) out of 12 farms. Four species of Eimeria were identified: E. acervulina (21/23; 91%), E. tenella (14/23; 61%), E. maxima (5/23; 22%) and E. praecox (3/23; 13%). Infection with a single species (E. acervulina) was detected in 6 (26%) infected flocks originated from large farms. Mixed infections were found in 15 (65%) flocks and the most prevalent combination was E. acervulina + E. tenella (8/23; 35%). Four flocks (17%) harboured mixed infection with E. acervulina + E. tenella + E. maxima. E. acervulina was significantly more prevalent in flocks that received ionophores as anticoccidial feed additives.

Real-time PCR-based quantification of Eimeria genomes: a method to outweigh underestimation of genome numbers due to PCR inhibition

Eimeria species parasites can cause the disease coccidiosis in all livestock species, most notably poultry. Traditional diagnostics such as faecal microscopy have now been supplemented by molecular assays including genus-specific and species-specific quantitative polymerase chain reaction (qPCR), although DNA extracted from faecal samples is commonly affected by PCR inhibition. This was confirmed when genomic DNA extracted from chicken faeces inhibited the threshold cycle value of internal positive control (IPC) DNA amplification by 15.33%. Hence, the objective of the present study was to use IPC qPCR to determine PCR inhibition in a series of experimental samples and use the increase in IPC qPCR threshold cycle value as an individual (sample-specific) correction factor for an established 5S rDNA qPCR used to estimate total Eimeria genome numbers. IPC-corrected genome counts were correlated with conventional oocyst per gram counts and compared with non-corrected counts, revealing a 0.1769 increase in correlation coefficient to outweigh underestimation of oocyst counts. Though the sample size used in this study is small, this limitation would be offset by the sample-specific correction factor determined using the IPC along with each sample.

Eimeria tiliquae n. sp. (Apicomplexa: Eimeriidae) from the shingleback skink (Tiliqua rugosa rugosa)

A new species, Eimeria tiliquae n. sp. is described from a shingleback skink (Tiliqua rugosa rugosa). Sporulated oocysts (n=50) are spherical to subspherical, with colourless trilaminate oocyst wall, 0.7±0.1 (0.5-0.75) thick. Oocyst with 4 spheroidal to subspheroidal sporocysts. Oocyst length, 13.7±0.9 (12.0-16.3); oocyst width, 12.8±0.9 (11.5-15.0); oocyst length/width (L/W) ratio, 1.07±0.05 (1.0-1.2). Micropyle, oocyst residuum and polar granule absent. Sporocysts with globular sporocyst residuum and 2 sporozoites. Sporocyst length, 6.0±0.6 (5.0-7.5); sporocyst width, 5.4±0.6 (4.0-7.0); sporocyst L/W ratio, 1.11±0.11 (1.0-1.5). Stieda, parastieda and substieda bodies absent. Phylogenetic analysis of 18S rRNA sequences indicated that E. tiliquae n. sp. shared 96.4-96.5% genetic similarity to E. tropidura, its closest relative. Reptile-derived sequences were not available for the mitochondrial cytochrome oxidase gene (COI) and phylogenetic analysis at this locus placed E. tiliquae n. sp. in a clade by itself but grouping closest (92% similarity) with a novel isolate from a King's skink (Egernia kingii) from Western Australia. Based on morphological and molecular data, this isolate is a new species of coccidian parasite that to date has only been found in shingleback skinks.

Effect of the granulometric characteristics of monensin sodium on controlling experimental coccidiosis in broiler chickens

The aim of the present study was to investigate the efficacy of monensin sodium grain size on controlling coccidiosis in broiler chickens. Three hundred and fifty Cobb 700 chicks were infected experimentally with 8 × 10(4) sporulated oocysts of Eimeria spp. The birds were fed with diets supplemented with powdered (n = 150) or granulated (n = 150) monensin, with particle sizes of ≤ 100 µm and 450-650 µm, respectively. The remaining chicks (n = 50) were used as an unmedicated control group. The birds' weights and number of oocysts per gram of litter in each group were recorded weekly. A total of 96 birds were randomly selected and culled during the trial. Their intestinal oocyst counts and lesion scores were determined. No significant differences in body weights were found between the groups at the end of the study. The percentages of infected animals, oocyst counts and lesion scores were significantly higher in the control group than in the other two groups; the two treated groups did not show any appreciable differences to each other. Enteritis was observed in 14 birds, all in the group supplemented with granulated monensin. These results suggest that powdered and granulated monensin have comparable efficacy in controlling coccidiosis in broiler chickens. However, treatments with monensin sodium of high grain size may be subject to contraindications relating to enteritis.

Pinning down a polymorphic parasite: new genetic and morphological descriptions of Eimeria macropodis from the Tammar wallaby (Macropus eugenii)

Identification of the protozoan parasite, Eimeria has traditionally relied on oocyst morphology, host range and life-cycle attributes. However, it is increasingly recognized that Eimeria species can vary in size and shape across their host range, an attribute known as 'polymorphism' that presents a unique challenge for identification. Advances in molecular tools hold promise for characterising Eimeria that may otherwise be misclassified based on morphology. Our study used morphologic and molecular traits of the oocyst life stage to identify a polymorphic parasite, Eimeria macropodis in a captive Tammar wallaby (Macropus eugenii) population in Australia. Molecular characterization highlighted the need to use multiple genetic markers (18S SSU and cytochrome c oxidase subunit I) to accurately identify E. macropodis owing to heterozygous alleles at the 18S SSU locus. This study provided an opportunity to assess the utility and shortcomings of morphologic and molecular techniques for 'pinning down' a polymorphic species. Moreover, our study was able to place E. macropodis in an evolutionary context and enhance resolution of the under-studied marsupial clade.

Eimeria biarmicus sp.n. (Apicomplexa: Eimeriidae) infecting falcons from the genus Falco in Saudi Arabia

The oocysts of Eimeria biarmicus sp. n. were described from the feces of the lanner falcon, Falco biarmicus, collected from the falcon market in Riyadh City, Saudi Arabia. The prevalence of infection was 5% (2/40). The majority of the oocysts examined had completed sporulation within 84 h at 24 ± 2°C. Sporulated oocysts are ovoid in shape, measuring 22.4 × 17.9 (20.5-24.7 × 15.8-18.5) μm; shape index (L/W) is 1.25 (1.14-1.36) μm. The oocyst wall is smooth and bi-layered. Micropyle and oocyst residuum are absent. A polar granule is present, consisting of 2-4 globules. Sporocysts are ovoid, 10.1 × 6.1 (9.4-11.2 × 5.4-6.8) μm; with a smooth single-layered wall and a minute Stieda body, but there is no substieda body. The sporocyst residuum consists of numerous small granules. Sporozoites are comma shaped, each contains two refractile bodies. E. biarmicus sp. n. is the second eimerian species described from F. biarmicus.

Liver response of rabbits to Eimeria coecicola infections

Intestinal coccidiosis of rabbits induced by E. coecicola causes enormous economic losses in rabbit farms. Here, we investigate the effect of E. coecicola on the liver of the rabbit Oryctolagus cuniculus. On day 7 p.i., fecal expulsion of E. coecicola oocysts is maximal and rabbits have lost approximately 25% of their weight. The liver, though not targeted by parasites, exhibits several signs of moderate inflammations, i.e., inflammatory cellular infiltrations around the central vein, dilatated blood sinusoids, increase in vacuolated hepatocytes, hypertrophic Kupffer cells, and lipid peroxidation as well as decreases in catalase and superoxide dismutase activities. Liver injuries are also indicated by an increase in blood plasma, by an increase in liver enzymes such as alanine transaminase, aspartate transaminase, alkaline phosphatase, and gamma glutamyl transferase, and a decrease in total protein and albumin. Circulating neutrophils have increased from 61% on day 0 p.i. to 71.3% on day 7 p.i., while lymphocytes are decreased from 37% to 26%. Agilent two-color oligo microarray technology, in combination with quantitative PCR, reveals that the expressions of 56 genes are upregulated and that of 22 genes are downregulated in the liver. The genes are largely involved in metabolism, calcium homeostasis, transport, and diverse signaling processes in the liver. In addition, numerous genes encoding for different regions of T-cell receptor as well as IgM, IgG, and IgA antibodies are both up- and downregulated in the liver by E. coecicola infections. The latter data suggest that the liver is not only 'passively' inflamed by intestinal infections with E. coecicola but rather is actively involved in the host defense against the intestinal Eimeria parasites.