A newly described strain of Eimeria arloingi (strain A) belongs to the phylogenetic group of ruminant-infecting pathogenic species, which replicate in host endothelial cells in vivo

Metaphylactic strategies using toltrazuril against coccidiosis in goat kids

Goat coccidiosis compromises animal welfare, reduces productivity and may cause mortality and delayed growth rates in goat kids around the weaning period worldwide. This field study was conducted to evaluate the efficacy of metaphylactic treatments with two doses of toltrazuril (20 or 40 mg/kg body weight - BW, p. o.), at different timing, in kids naturally infected with Eimeria spp. A total of 97 healthy goat kids (Majorera milk aptitude breed) were divided into five groups, depending on the age of treatment (2 or 7 weeks). One group remained untreated as a negative control until the end of the study. Faecal oocyst shedding, faecal consistency, and body weight of the animals were monitored at day 0 and at weekly intervals. Counts of oocysts per gram of faeces (OPG) were determined by a modified McMaster technique. Morphometric identification of Eimeria species was carried out on individual faecal samples from each experimental group after oocyst sporulation. Goat kids treated at two weeks of age maintained OPG values close to zero during the 5 weeks post-treatment and, overall, had lower faecal oocyst counts than untreated control animals. No significant differences were observed between the two doses of toltrazuril used in two-week-old treated animals. By contrast, when treatment was carried out at seven weeks of age, the dose of 40 mg/kg BW of toltrazuril reduced oocyst levels for longer and to a greater extent than the 20 mg/kg dose. Irrespectively of the treatment and dose, toltrazuril delayed the appearance of pathogenic Eimeria species, i. e. Eimeria ninakohlyakimovae and Eimeria arloingi. As a whole, Eimeria christenseni, with a rather moderate pathogenicity, was highly predominant throughout the study period, including the untreated control group, which was probably the reason why clinical signs of coccidiosis were barely observed throughout the experiment. Under these circumstances, the positive effect of toltrazuril on body weight condition observed in some treated groups was difficult to correlate to the timing and doses. Metaphylactic treatments with 20 mg/kg BW toltrazuril given at two weeks of age are sufficient to control oocyst excretion in goat kids; whereas if administered later in 7-week-old animals, thereby coinciding with the frequently observed peak of oocyst elimination in goat kids under field conditions, a higher dose might be advisable to prevent environmental contamination with infectious oocysts.

Eimeria zuernii (Eimeriidae: Coccidia): mitochondrial genome and genetic diversity in the Chinese yak

BACKGROUND

Coccidiosis caused by Eimeria zuernii (Eimeriidae: Coccidia) represents a significant economic threat to the bovine industry. Understanding the evolutionary and genetic biology of E. zuernii can assist in new interaction developments for the prevention and control of this protozoosis.

METHODS

We defined the evolutionary and genetic characteristics of E. zuernii by sequencing the complete mitogenome and analyzing the genetic diversity and population structure of 51 isolates collected from eight yak breeding parks in China.

RESULTS

The 6176-bp mitogenome of E. zuernii was linear and encoded typical mitochondrial contents of apicomplexan parasites, including three protein-coding genes [PCGs; cytochrome c oxidase subunits I and III (cox1 and cox3), and cytochrome b (cytb)], seven fragmented small subunit (SSU) and 12 fragmented large subunit (LSU) rRNAs. Genome-wide comparative and evolutionary analyses showed cytb and cox3 to be the most and least conserved Eimeria PCGs, respectively, and placed E. zuernii more closely related to Eimeria mephitidis than other Eimeria species. Furthermore, cox1-based genetic structure defined 24 haplotypes of E. zuernii with high haplotype diversities and low nucleotide diversities across eight geographic populations, supporting a low genetic structure and rapid evolutionary rate as well as a previous expansion event among E. zuernii populations.

CONCLUSIONS

To our knowledge, this is the first study presenting the phylogeny, genetic diversity, and population structure of the yak E. zuernii, and such information, together with its mitogenomic data, should contribute to a better understanding of the genetic and evolutionary biological studies of apicomplexan parasites in bovines.

Investigation and molecular identification of Eimeria sp. sampled from captive forest musk deer

Forest musk deer (Moschus berezovskii) is an endangered, protected species in China. Intestinal coccidiosis is a significant problem for captive forest musk deer. However, there are few reports on the prevalence and molecular characteristics of Eimeria sp. in forest musk deer. We sought to investigate the prevalence of Eimeria sp. in forest musk deer in the Sichuan and Shaanxi provinces in China. We also investigated the molecular characteristics of Eimeria sp. by analyzing the 18S rRNA gene. We collected a total of 328 fecal samples from forest musk deer on seven farms throughout the Sichuan and Shaanxi provinces. We extracted this parasite’s DNA and used this as a template for nested PCR amplification. The 18S rRNA gene fragment was associated with the plasmid vector, and these products were introduced into Escherichia coli (DH5α). The cultured bacterial solution was used as a PCR reaction template for identification purposes. We collected 328 fecal samples from forest musk deer in Lixian (n = 54), Maoxian (n = 52), Ma’erkang (n = 49), Dujiangyan (n = 55), Hanyuan (n = 41), Luding (n = 36) and Weinan (n = 41). One hundred ninety-eight (60.37%) fecal samples tested positive for Eimeria sp. . In our analysis of the 18S rRNA gene we found 34 types of Eimeria sp. with a similarity of 90.5–100%. We constructed a phylogenetic tree based on the parasite’s 18S rRNA gene sequence. Our findings indicated that the Eimeria sp. that parasitized the intestinal tract of forest musk deer was closely related to Eimeria alabamensis from Bos taurus and Eimeria ahsata from Ovis aries. To the best of our knowledge, ours was the first investigation and molecular identification of Eimeria sp. sampled from captive forest musk deer in China. Our results provide epidemiological data for the monitoring and prevention of Eimeria sp. in captive forest musk deer.

Analysis of potential risk factors of caprine coccidiosis

Caprine coccidiosis represents a major concern in goat industry worldwide causing high economic losses, mainly due to poor weight gains, treatment costs and even death of kids. Therefore, analyses on risk factors involved in the establishment and outcome of this disease are important to improve infection status and herd management. In Portugal, approximately 400,000 goats are reared every year. The majority of them are allocated in the southern part of the country. In the current study, a representative number of animals (382 goats) and herds (37 herds) from Alentejo were monitored. Faecal samples from five young and five adult goats of each farm were collected rectally and examined individually by using the modified McMaster technique for oocyst counts (oocyst per gram of faeces - OPG). Additionally, a questionnaire on the husbandry conditions and anti-parasitic treatments was performed. Overall, a prevalence of Eimeria infections of 99% and 100% was detected on animal and herd level, respectively. Eimeria arloingi and E. ninakohlyakimovae as the two most pathogenic caprine species also constituted the most prevalent ones (34.91% and 29.90%, respectively), both in the young and the adult goat groups. As expected, OPG vales were significantly higher (p = 0.031) in young than in adult goats. Furthermore, risk factor analyses revealed young age, higher total number of animals on the farm and outdoor kidding as strongly associated with a higher risk of caprine coccidiosis. Overall, the high prevalence of pathogenic Eimeria species on Portuguese goat farms in combination with the occurrence of related risk factors strengthen the importance of coccidiosis control in caprine industry.

Optimized excystation protocol for ruminant Eimeria bovis- and Eimeria arloingi-sporulated oocysts and first 3D holotomographic microscopy analysis of differing sporozoite egress

Successful excystation of sporulated Eimeria spp. oocysts is an important step to acquire large numbers of viable sporozoites for molecular, biochemical, immunological and in vitro experiments for detailed studies on complex host cell-parasite interactions. An improved method for excystation of sporulated oocysts and collection of infective E. bovis- and E. arloingi-sporozoites is here described. Eimeria spp. oocysts were treated for at least 20 h with sterile 0.02 M _L-cysteine HCl/0.2 M NaHCO₃ solution at 37 °C in 100% CO₂ atmosphere. The last oocyst treatment was performed with a 0.4% trypsin 8% sterile bovine bile excystation solution, which disrupted oocyst walls with consequent activation of sporozoites within oocyst circumplasm, thereby releasing up to 90% of sporozoites in approximately 2 h of incubation (37 °C) with a 1:3 (oocysts:sporozoites) ratio. Free-released sporozoites were filtered in order to remove rests of oocysts, sporocysts and non-sporulated oocysts. Furthermore, live cell imaging 3D holotomographic microscopy (Nanolive®) analysis allowed visualization of differing sporozoite egress strategies. Sporozoites of both species were up to 99% viable, highly motile, capable of active host cell invasion and further development into trophozoite- as well as macroment-development in primary bovine umbilical vein endothelial cells (BUVEC). Sporozoites obtained by this new excystation protocol were cleaner at the time point of exposure of BUVEC monolayers and thus benefiting from the non-activation status of these highly immunocompetent cells through debris. Alongside, this protocol improved former described methods by being is less expensive, faster, accessible for all labs with minimum equipment, and without requirement of neither expensive buffer solutions nor sophisticated instruments such as ultracentrifuges.

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.

Emerging threat of Eimeria operational taxonomic units (OTUs) on poultry production

Coccidiosis is an antagonistic poultry disease which negatively impacts animal welfare and productivity. The disease is caused by an obligate, intracellular protozoon known as Eimeria. Several Eimeria species known to infect chickens have been well documented. However, recent studies have elucidated the emergence of three novel genetic variants or operational taxonomic units (OTUs). The discovery of OTUx, OTUy and OTUz complicates the identification and diagnosis of coccidiosis. OTUs are clusters of unknown or uncultivated organisms that are grouped according to a similarity in DNA sequence to a set of specific gene markers. OTUs have been reported in the Earth's Southern Hemisphere, including Australia, Venezuela, India, Zambia, Uganda, Tanzania, China and Ghana. Elucidating their impact on the poultry industry is fundamental in preventing anticoccidial resistance and to access the potential of OTUs as vaccine candidates to provide cross-protection against similar Eimeria species. The identification of OTUs further decreases the risk of false negative coccidial diagnosis. Therefore, this article reviews the importance and risk imposed by OTUs, coupled with their prevalence and geographical distribution in chickens globally.