Epidemiological investigation and risk factors of Echinococcus granulosus in yaks (Bos grunniens), Tibetan pigs and Tibetans on Qinghai Tibetan plateau

Prevalence and Molecular Characterization of Parasitic Lice in Tibetan Yaks, Pigs and Sheep

The infestation of ectoparasites poses a severe problem in animal breeding, severely affecting animal health and causing substantial economic losses. However, limited information is available regarding lice infestations in plateau livestock. To address this, we collected and examined lice samples from Tibetan yaks, pigs and sheep, amplifying the rrnS and cox1 genes for evolutionary analysis. The results revealed that the prevalence of lice was 51.3% (95% CI: 44.0-58.6%) in yaks, Tibetan sheep and Tibetan pigs, with regional prevalence ranging from 7.7% to 67.5%. Morphometric analysis showed that female lice were bigger than male lice. In Tibetan pigs, females exhibited a prominent longer body length (p < 0.05), belly length (p < 0.01) and body length to body width ratio (p < 0.05). In yaks, females had longer body length (p < 0.01) and body width (p < 0.05). For Tibetan sheep, female lice had larger body length (p < 0.001), body width (p < 0.001), head length (p < 0.05) and belly length (p < 0.05). Additionally, molecular identification revealed that lice infesting wild and domestic yaks were Linognathus vituli with 96.59-98.78% (wild yaks) and 96.33-98.71% (yaks) similarity to the OL677823.1 isolate. Lice infesting Tibetan sheep were identified as Linognathus africanus, showing 99.02-99.76% similarity to the OP948898.1 isolate. Lice from Tibetan pigs were identified as Haematopinus apri, with 96.38-98.31% similarity to the ON000922.1 isolate. Moreover, cox1 gene analysis of lice from Tibetan pigs showed 96.97-97.72% similarity to the KC814616.1 isolate. It is concluded that these findings could provide valuable insights into the prevention and control of lice-related diseases in plateau animals, enhancing animal health and mitigating economic losses.

Effects of thermal processing and temperature on the quality, protein oxidation, and structural characteristics of yak meat

The aim of this study was to determine the effects of processing on the quality, protein oxidation, and structural properties of yak meat. The cooking loss, Warner-Bratzler shear force, meat color, texture, thiobarbituric acid reactive substance, total carbonyl content (TCC), total sulfhydryl content (TSC), and structural properties of yak meat under frying, drying, and boiling were measured. The results showed that the cooking loss rate, shear force, L* value, hardness, elasticity, and chewiness of yak meat increased (p < .05) and the a* value decreased (p < .05) with increasing central temperature after processing. Fried yak meat at 80°C had the lowest cooking loss rate of 42.21% and the lowest shear force of 50.86 N, which had better textural characteristics, followed by boiling, while the maximum cooking loss rate, hardness, and shear force were 1.40 times, 1.26 times, and 1.2 times that of frying, respectively. The thiobarbituric acid reactive substance was obtained after decoction and peaked at 1.88 ± 0.04 mmol/mg at 60°C. The highest TCC and the lowest TSC were obtained for dried proteins at 80°C. In addition, as the central temperature increased, the helical structure in the protein secondary structure decreased, the disordered structure increased, the fluorescence intensity of myofibrillar proteins decreased, and protein degradation occurred. It was concluded that dried yak meat had the highest protein oxidation and the worst quality, while fried yak meat had the lowest protein oxidation and the best quality.

EgSeverin and Eg14-3-3zeta from Echinococcus granulosus are potential antigens for serological diagnosis of echinococcosis in dogs and sheep

Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the metacestode larva of Echinococcus granulosus. In this study, two-dimensional gel electrophoresis (2-DE) coupled with immunoblot analysis revealed that E. granulosus severin and 14-3-3zeta proteins (named EgSeverin and Eg14-3-3zeta, respectively) might be two potential biomarkers for serological diagnosis of echinococcosis. The recombinant EgSeverin (rEgSeverin, 45 kDa) and Eg14-3-3zeta (rEg14-3-3zeta, 35 kDa) were administered subcutaneously to BALB/c mice to obtain polyclonal antibodies for immunofluorescence analyses (IFAs). And IFAs showed that both proteins were located on the surface of protoscoleces (PSCs). Western blotting showed that both proteins could react with sera from E. granulosus-infected sheep, dog, and mice. Indirect ELISAs (rEgSeverin- and rEg14-3-3zeta-iELISA) were developed, respectively, with sensitivities and specificities ranging from 83.33% to 100% and a coefficient of variation (CV %) of less than 10%. The rEgSeverin-iELISA showed cross-reaction with both E. granulosus and E. multilocularis, while the rEg14-3-3zeta-iELISA showed no cross-reaction with other sera except for the E. granulosus-infected ones. The field sheep sera from Xinjiang and Qinghai were analyzed using rEgSeverin-iELISA, rEg14-3-3zeta-iELISA, and a commercial kit respectively, and no significant differences were found among the three methods (p > 0.05). However, the CE positive rates in sheep sera from Qinghai were significantly higher than those from Xinjiang (p < 0.01). Overall, the results suggest that EgSeverin and Eg14-3-3zeta could be promising diagnostic antigens for E. granulosus infection.

Complete genome analysis of Bacillus subtilis derived from yaks and its probiotic characteristics

Probiotics have attracted attention due to their multiple health benefits to the host. Yaks inhabiting the Tibetan plateau exhibit excellent disease resistance and tolerance, which may be associated with their inner probiotics. Currently, research on probiotics mainly focuses on their positive effects on the host, but information regarding their genome remains unclear. To reveal the potential functional genes of Bacillus subtilis isolated from yaks, we sequenced its whole genome. Results indicated that the genomic length of Bacillus subtilis was 866,044,638 bp, with 4,429 coding genes. The genome of this bacteria was composed of one chromosome and one plasmid with lengths of 4,214,774 and 54,527 bp, respectively. Moreover, Bacillus subtilis contained 86 tRNAs, 27 rRNAs (9 16S_rRNA, 9 23S_rRNA, and 9 5S_rRNA), and 114 other ncRNA. KEGG annotation indicated that most genes in Bacillus subtilis were associated with biosynthesis of amino acids, carbon metabolism, purine metabolism, pyrimidine metabolism, and ABC transporters. GO annotation demonstrated that most genes in Bacillus subtilis were related to nucleic acid binding transcription factor activity, transporter activity, antioxidant activity, and biological adhesion. EggNOG uncovered that most genes in Bacillus subtilis were related to energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism. CAZy annotation found glycoside hydrolases (33.65%), glycosyl transferases (22.11%), polysaccharide lyases (3.84%), carbohydrate esterases (14.42%), auxiliary activities (3.36%), and carbohydrate-binding modules (22.59%). In conclusion, this study investigated the genome and genetic properties of Bacillus subtilis derived from yaks, which contributed to understanding the potential prebiotic mechanism of probiotics from the genetic perspective.

Cryptosporidium infection induced the dropping of SCFAS and dysbiosis in intestinal microbiome of Tibetan pigs

The infection of Cryptosporidium in pigs causes digestive system ailments, diarrhea and weight loss serving as an economic burden, especially in newborn animals. The bacterial fermentation products of short-chain fatty acids have important roles in immune function, microbiota regulation, osmotic balance and metabolism. However, till now little knowledge is available about the effect of Cryptosporidium infection on microbiota and SCFAs in plateau pigs. Hence, we performed this study to explore the response of microbiota and SCFAs in the natural infection of Cryptosporidium in Tibetan pigs. Cryptosporidium positive (infected, G) and negative samples (healthy, J) in our previous study were used for high throughputsequencing and Gas Chromatography-Mass Spectrometer analysis. Over 81 000 and 74 000 filtered sequences were detected in healthy and infected Tibetan pigs, respectively. Lower sample richness and evenness were observed in Cryptosporidium infection, as alpha diversity analysis found that chao1 (p < 0.05), faith_pd (p < 0.05), and observed_features in group G were significantly lower than pigs in group J. A total of 4 and 27 significant different phyla and genera were found between group G and J. The changed genera were Psychrobacter, Desemzia, Succiniclasticum, Treponema, Campylobacter, Atopobium, Olsenella, Pediococcus, Peptococcus, Sharpea, Desulfovibrio, Acinetobacter, Rhodococcus, Anaerostipes, Turicibacter, Lactobacillus, RFN20, Phascolarctobacterium, Roseburia, Megasphaera, Streptococcus, Blautia, Lachnospira, rc4_4, Gemmiger, Dorea, Oribacterium and Prevotella, which affected the microbiota functions with 360 abundance changed enzymes, and pathways in L1, L2 and L3 levels of KEGG. The concentration of acetic acid (p < 0.01), butyric acid (p < 0.05) and caproic acid (p < 0.01) were lower in group G. In conclusion, the present study herein uncovered that the host responses to Cryptosporidium infection in Tibetan pigs with 27 of significantly changed genera decreased SCFAs in pigs, which may provide insights in further developing novel therapy against this protozoan.

Genetic diversity of Echinococcus granulosus sensu lato in China: Epidemiological studies and systematic review

Cystic echinococcosis (CE) is a neglected tropical zoonosis caused by Echinococcus granulosus sensu lato (s.l.) and remains a major public health concern globally. Here, CE isolates (n = 3310) with clearly defined genotypes and geographical origins in China were retrieved through our epidemiological survey (2016-2020) and systematic review (1992-2020). Existing known genotypes of Echinococcus granulosus sensu lato (E. granulosus s.l.) except for G4 have been found in China, particularly on the Tibetan Plateau, where their genetic diversity is unique to that part of the world. According to the systematic review, genetic compositions of E. granulosus s.l. in China were as follows: E. granulosus (G1, G3), 98.3%; Echinococcus ortleppi (G5), 0.1%; Echinococcus intermedius (G6, G7), 1.4%; and Echinococcus canadensis (G8, G10), 0.2%. Specifically, G1 was responsible for 97.7% of infections and characterized by the broadest host ranges and geographic distributions. Our epidemiological results showed a relatively stable genetic composition of E. granulosus s.l. in sheep and yaks from three CE hyperendemic provinces (Xinjiang, Sichuan, Qinghai). A higher proportion of fertile cysts were found in sheep (287/406, 70.7%) than in yaks (28/184, 15.2%). During the past 29 years, 51 cox1 haplotypes of E. granulosus s.l. were endemic in China. The ancestral haplotype (Hap_2) remained the most common haplotype, 12 relatively common haplotypes were endemic and nine newly reported haplotypes were found during the survey. Overall, our results demonstrate that the compulsory immunization of sheep and the pilot EG95 vaccination campaign in yaks are well matched with the current genotypic situation. In addition to yaks, we advocate for more surveillance of CE isolates from pigs, cattle, goats and camels, since their roles in the transmission and reservation of E. granulosus s.l. have been largely ignored in China.

Risk Factors Associated With Echinococcosis in the General Chinese Population: A Meta-Analysis and Systematic Review

Background

Echinococcosis is a severe zoonotic disease that imposes a substantial burden on human life. This meta-analysis aimed to summarize available data on the prevalence of human echinococcosis and identify the key risk factors for echinococcosis in the Chinese general population.

Methods

Relevant studies were comprehensively searched in the PubMed, EMBASE, Web of Science, Cochrane, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP Information (VIP), Wanfang and SinoMed databases until August 22, 2020. A random-effects model was used to estimate the pooled odds ratio (OR) and 95% confidence interval (95% CI). The I² and Q statistics were calculated to evaluate the heterogeneity, and potential sources of heterogeneity were identified using sensitivity analysis and subgroup analysis. Publication bias was estimated by funnel plots and Egger's test.

Results

A total of 1026 studies were identified through the database search, of which 26 were eligible for this meta-analysis. The pooled prevalence of AE and CE were 2.88% and 5.66%, respectively. Ethnicity (OR = 2.93, 95% CI: 1.81–4.75; I² = 0), herdsman occupation (OR = 2.66, 95% CI: 2.25–3.14; I² = 8.0%), not washing hands before meals (OR = 2.40, 95% CI: 1.34–4.28; I² = 82.8%) and being female (OR = 1.45, 95% CI: 1.26–1.66; I² = 33.9%) were risk factors for AE. The top five risk factors for CE were ethnicity (OR = 3.18, 95% CI: 1.55–6.52; I² = 79.2%), nomadism (OR = 2.71, 95% CI: 1.65–4.47; I² = 55.8%), drinking nonboiled water (OR = 2.47, 95% CI: 1.36–4.47; I² = 85.7), feeding viscera to dogs (OR = 2.35, 95% CI: 1.89–2.91; I² = 21.5%), and herdsman occupation (OR = 2.19, 95% CI: 1.67–2.86; I² = 85.1%).

Conclusions

This study generalized articles that have contributed to our current understanding of the epidemic of human echinococcosis (AE and CE) in China over the years. The results support that the ethnicity and dog-related factors are major risk factors for both CE and AE. The identification of echinococcosis risk factors may aid researchers and policymakers in improving surveillance and preventive measures aimed at reducing Echinococcus granulosus and Echinococcus multilocularis infection in humans.

Seroprevalence of Cystic Echinococcosis in Yaks and Sheep During 2017 on the Qinghai–Tibet Plateau, China

Cystic echinococcosis (CE) is a livestock disease caused by a parasite known as Echinococcus granulosus. It is one of the primary cause for illness and poverty especially for herders on the Qinghai–Tibet plateau, China. Meanwhile, the Qinghai–Tibet plateau has been a key area for echinococcosis control in China. Here in current study, we determined the seroprevalence of E. granulosus in ruminants on this region. A total of 2,730 serum samples (1,638 samples from yaks and 1,092 samples from sheep) were collected on the plateau during the period of 2017. The samples were assayed for E. granulosus antibodies by commercial enzyme-linked immunosorbent assay kits. Our results exhibited a prevalence percentage of 52.2% in Tibetan yaks and 38.2% in Tibetan sheep. Moreover, there was more chance of being infected with E. granulosus infection in old animals due to more exposure to contaminated sources of infection. However, no significant difference was observed. Furthermore, we observed that the rainfall and presence of several lakes has increased the risk of CE infection in yaks and sheep in the Qinghai, Qinglong, and Baingoin areas. Hence, with this investigation, it was possible to determine the frequency and distribution of CE in yaks and Tibetan sheep on the Qinghai-Tibet plateau, that laying the groundwork for its prevention and management.

Effects of Short-Chain Fatty Acid Modulation on Potentially Diarrhea-Causing Pathogens in Yaks Through Metagenomic Sequencing

Short-chain fatty acids (SCFA) are principal nutrient substrates of intestinal epithelial cells that regulate the epithelial barrier in yaks. Until now, metagenomics sequencing has not been reported in diarrheal yaks. Scarce information is available regarding the levels of fecal SCFA and diarrhea in yaks. So, our study aims to identify the potential pathogens that cause the emerging diarrhea and explore the potential relationship of short-chain fatty acids in this issue. We estimated diarrhea rate in yaks after collecting an equal number of fecal samples from affected animals. Metagenomics sequencing and quantitative analysis of SCFA were performed, which revealed 15%–25% and 5%–10% prevalence of diarrhea in yak’s calves and adults, respectively. Violin box plot also showed a higher degree of dispersion in gene abundance distribution of diarrheal yaks, as compared to normal yaks. We found 366,163 significant differential abundance genes in diarrheal yaks, with 141,305 upregulated and 224,858 downregulated genes compared with normal yaks via DESeq analysis. Metagenomics binning analysis indicated the higher significance of bin 33 (Bacteroidales) (p < 0.05) in diarrheal animals, while bin 10 (p < 0.0001), bin 30 (Clostridiales) (p < 0.05), bin 51 (Lactobacillales) (p < 0.05), bin 8 (Lachnospiraceae) (p < 0.05), and bin 47 (Bacteria) (p < 0.05) were significantly higher in normal yaks. At different levels, a significant difference in phylum (n = 4), class (n = 8), oder (n = 8), family (n = 16), genus (n = 17), and species (n = 30) was noticed, respectively. Compared with healthy yaks, acetic acid (p < 0.01), propionic acid (p < 0.01), butyric acid (p < 0.01), isobutyric acid (p < 0.01), isovaleric acid (p < 0.05), and caproic acid (p < 0.01) were all observed significantly at a lower rate in diarrheal yaks. In conclusion, besides the increased Staphylococcus aureus, Babesia ovata, Anaplasma phagocytophilum, Bacteroides fluxus, viruses, Klebsiella pneumonia, and inflammation-related bacteria, the decrease of SCFA caused by the imbalance of intestinal microbiota was potentially observed in diarrheal yaks.

Characterization of Bacterial Microbiota Composition in Healthy and Diarrheal Early-Weaned Tibetan Piglets

The occurrence of diarrhea in Tibetan piglets is highly notable, but the microorganisms responsible are yet unclear. Its high incidence results in serious economic losses for the Tibetan pig industry. Moreover, the dynamic balance of intestinal microflora plays a crucial role in maintaining host health, as it is a prime cause of diarrhea. Therefore, the present study was performed to analyze the characteristics of bacterial microbiota structure in healthy, diarrheal and treated weaned piglets in Tibet autonomous region for providing a theoretical basis to prevent and control diarrhea. The study was based on the V3–V4 region of the 16S rRNA gene and gut microbiota functions following the metagenome analysis of fresh fecal samples (n = 5) from different groups. The Shannon and Simpson indices differed substantially between diarrheal and treated groups (p < 0.05). According to our findings, the beta diversities, especially between healthy and diarrheal groups, were found different. Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla in three groups. Furthermore, the abundance of Fusobacteria in the diarrheal group was higher than the other groups. The dominant genera in the diarrheal group were Fusobacterium, Butyricimonas, Sutterella, Peptostreptococcus, and Pasteurella. Moreover, Lactobacillus, Megasphaera and Clavibacter were distinctly less abundant in this group. It is noteworthy that the specific decrease in the abundance of pathogenic bacteria after antibiotic treatment in piglets was noticed, while the level of Lactobacillus was evidently increased. In conclusion, fecal microbial composition and structure variations were discovered across the three groups. Also, the ecological balance of the intestinal microflora was disrupted in diarrheal piglets. It might be caused by a reduction in the relative number of beneficial bacteria and an increase in the abundance of pathogenic bacteria. In the context of advocating for non-resistant feeding, we suspect that the addition of probiotics to feed may prevent early-weaning diarrhea in piglets. Moreover, our findings might help for preventing diarrhea in weaned Tibetan piglets with a better understanding of microbial population dynamics.

Focusing on intramuscular connective tissue: Effect of cooking time and temperature on physical, textual, and structural properties of yak meat

This study aimed to evaluate the effects of different cooking time (2, 4, and 6 h) and temperature (50, 60, 70, 80, and 90 °C) on physical, textual, and structural properties of longissimus lumborum muscle of yak, and to explore the thermal denaturation process of intramuscular collagen by using a new tool (collagen hybridizing peptide staining, CHP staining). The results showed that tenderness was affected by the interaction of cooking time and temperature and the changes in moisture and collagen composition. In comparison with cooking time, temperature had more obvious effects on cooking loss, moisture content and redness. Scanning electron microscopy showed that as the temperature increased, intramuscular connective tissue gradually degraded, and muscle fibers became more compact. CHP staining showed that the collagen in the perimysium first denatured at 50 °C, and more and more collagen denatured and degraded as the temperature increased.

Prevalence, Characterization, and Pathogenicity of Salmonella enterica Subspecies enterica Serovar Derby from Yaks in the Aba Tibetan Autonomous Prefecture, China

Simple Summary

Salmonella spp. is a very important pathogen in the livestock industry and public health, which poses a major threat to global public health. Yaks and their by-products have a significant economic status in the Qinghai–Tibetan Plateau. The aim of this study was to investigate the prevalence of salmonella in yak farms and to conduct a molecular characterization and tests on its pathogenicity in mice with the use of salmonella isolated from yaks with diarrhea as well as from drinking water samples. The prevalence of salmonella was 19.75% of 162 samples collected from yak farms, and all isolates were found to belong to the serovar of Salmonella Derby and ST40. All Salmonella Derby isolates from both fecal and drinking water samples from 13 farms were clonally related based on SNP alignment. Salmonella Derby was still detected positively in the feces of model mice on day 24 post-injection. This study reports the prevalence of Salmonella Derby in yaks with diarrhea and in their drinking water. In addition, the pathogenicity of the S. Derby in mice was investigated. Findings suggest that Salmonella Derby excreted by diarrheic yaks is a source of contamination for other yaks and the environment and is highly pathogenic to mice. Seeing that Salmonella Derby has become one of the most common Salmonella serovars, this situation gives rise to further risk from the potential spread of food-borne diseases.

Abstract

Salmonella enterica subsp. enterica serovar Derby (S. Derby) is one of the numerous non-typhoidal Salmonella serovars and has been recognized as a food-borne pathogen. In 2019, outbreaks of salmonellosis were reported in 13 yak farms in the Aba Tibetan Autonomous Prefecture, China. A total of 32 salmonella strains were isolated from 162 fecal samples of yaks with diarrhea as well as from drinking water samples. The isolates were subjected to serovar identification, animal experiments, and whole-genome sequencing (WGS) analyses. The serovar of all the isolates was S. Derby, and the sequence types (STs) were ST40. The analysis of the differences of single-nucleotide polymorphisms (SNPs) showed that the salmonella strains isolated from 13 farms were clonally related. Animal experiments showed that the lethal dose (LD₅₀) was 4.57 × 10⁷ CFU (colony-forming units); the shedding time of S. Derby in mice was 24 days; the bacterial loads in spleen were higher than those in other organs (ileum, liver, and cecum). Pathological analyses by hematoxylin and eosin (H&E) staining revealed obvious damage in the spleen, liver, and intestine. These results indicate that the S. Derby from yaks can cause infection in mice.

Advances in research on echinococcoses epidemiology in China

Echinococcoses are serious zoonotic diseases in China's vast, western and north-western pastoral areas that has one of the highest prevalence in the world. The two most common forms, cystic echinococcosis (CE) and alveolar echinococcosis (AE), are co-epidemic in some areas causing a grave threat to people's health and economic development. Echinococcus spp. are transmitted through domestic, sylvatic and mixed cycles involving many kinds of host. Successful transmission requires a favourable environment for the growth of the parasites and survival of their eggs, while the unique customs and religious beliefs in the endemic areas pose a challenge to the prevention and control of these parasites. Based on previous epidemiological studies, this paper reviews the particular factors affecting the transmission of Echinococcus parasites in China, with a focus on biological (parasite genotype and the species, age, sex and density of hosts), environmental (landscape and climate) and social (age, gender, ethnicity, education, occupation, life style, cultural customs, living conditions and hygiene practices of humans in the endemic areas). These three factors interact with each other and jointly determine the parasites' transmission intensity, the study of which supports the formulation of the strategies and measures that are significant for control of these infections.

Microbiome Analysis Reveals the Attenuation Effect of Lactobacillus From Yaks on Diarrhea via Modulation of Gut Microbiota

Domestic yaks (Bos grunniens) are indigenous to the Tibetan Plateau and display a high diarrhea rate due to poor habitat and husbandry conditions. Lactobacillus has been shown to exert beneficial effects as antimicrobial, growth promotion, and gut microbiota in humans and/or murine models, but the relevant data regarding Lactobacillus isolated from yaks was unavailable. Therefore, this study aimed to investigate the effects of Lactobacillus from yaks on the intestinal microbial community in a mouse model and determine whether Lactobacillus supplementation contributed in alleviating diarrhea by modulating gut microbiota. A total of 12 ileac samples from four groups were collected for 16S rRNA gene amplicon sequencing of V3-V4 region. Results revealed that although Lactobacillus supplementation did not change the diversity of gut microbiota in mice, the proportion of some intestinal microbiota significantly changed. Specifically, the proportion of Lactobacillus and Sphingomonas in the Lactobacillus treated-group (L-group) were increased as compared to control group (C-group), whereas Pantoea, Cutibacterium, Glutamicibacter, Turicibacter, Globicatella, Microbacterium, Facklamia, unidentified_Corynebacteriaceae, Brachybacterium, and Staphylococcus were significantly decreased in the L-group. In contrast, Escherichia coli (E. coli) infection significantly decreased the proportion of beneficial bacteria such as Globicatella, Acinetobacter, Aerococcus, and Comamonas, while loads of pathogenic bacteria significantly increased including Roseburia and Megasphaera. Interestingly, Lactobacillus administration could ameliorate the microbial community structure of E. coli-induced diarrheal mice by reducing the relative abundance of pathogenic bacteria such as Paenibacillus, Aerococcus, Comamonas, Acinetobacter, Corynebacterium, Facklamia, and Globicatella. Results in this study revealed that Lactobacillus supplementation not only improved the gut microbiota but also alleviated diarrhea in mice, which may be mediated by modulating the composition and function of gut microbiota. Moreover, this study is expected to provide a new theoretical basis for the establishment of a preventive and treatment system for diarrhea in yaks.

In-House Developed ELISA Indicates High Prevalence of Anti-Echinococcus granulosus IgG in Sheep Population-An Update from Pakistan

Cystic echinococcosis (CE) is a World Health Organization (WHO)-listed neglected tropical farm economy jeopardizing and public health concern disease. This study was aimed at furnishing sero-epidemiological baseline data of CE in sheep in Pakistan, where data are non-existent. For this purpose, two sheep-rich provinces of Pakistan were selected, and 728 sheep sera were collected using probability proportional to size (PPS) statistical technique. Epidemiological information was recorded on a questionnaire for the estimation of potential risk factors. The serum samples were analyzed for IgG antibodies against Echinococcus granulosus using an in-house-developed EgAgB-based ELISA kit. The overall seroprevalence recorded was 21.98% (160/728) in the tested sheep, suggesting higher seropositivity in sheep from Punjab (23.73%) as compared to Khyber Pakhtunkhwa (KPK) (19.04%). The overall apparent prevalence observed by this ELISA method was almost similar to the calculated true prevalence (21.77%). Prevalence was significantly different (p < 0.05) among sheep from different districts. Higher prevalence was found in females (22.54%, OR 1.41), age group > 5 years (29.66%, OR 1.64), crossbreeds (42.85%, OR 2.70), and sheep with pasture access (25.96%, OR 3.06). Being in age group > 5 years and having pasture access were the factors significantly associated with seropositivity (p < 0.05). This study provides serological evidence of E. granulosus infection in sheep and can be used as a model for ante-mortem screening of the sheep globally.

Prevalence and molecular characterization of Cryptosporidium spp. in yaks (Bos grunniens) in Naqu, China

The intestinal protozoan specie, Cryptosporidium causes serious diarrheal syndrome in humans and animals worldwide. However, limited knowledge is known about the infection caused by this specie in yaks in Naqu. About 950 serum and 150 fecal samples were collected and assayed by using commercial ELISA kits and nPCR detection methods to find the prevalence and molecular characterization of Cryptosporidium spp. in yaks. Results found that 103 out of 950 (10.8%) serums were uncovered against C. parvum antibodies. In different regions, the prevalence of C. parvum in yaks were in a range from 9.1% to 16.7%, with obvious difference among the three areas (P < 0.001). In male and female yaks, the prevalence of C. parvum was found to be 7.2% and 13.3% respectively (P < 0.001); and a significant difference (P < 0.001) with a range of 9.8%-18.2% was observed among different age groups. Out of 150 fecal samples, only 2 (1.3%) positive samples were detected via nPCR. The positive samples were sequenced and identified to be C. bovis. The two isolates were clustered to cattle and yak clade separately. Our results highlight the prevalence and epidemiological status of Cryptosporidium spp. in yaks which may contribute towards the prevention and control of this zoonotic disease in Naqu, China.

Seroprevalence of Echinococcus spp. and Toxocara spp. in Invasive Non-native American Mink

Invasive non-native species can become reservoirs of zoonotic pathogens and cause their spread during colonization, increasing the risk of zoonoses transmission to both wild hosts and humans. American mink (Neovison vison) are considered an important invasive mammal species responsible for carrying endoparasites. The aim of our study was to evaluate the role of feral American mink as a possible transmission vector of Echinococcus spp. and Toxocara spp. in wildlife. We analysed the frequency of American mink exposure to both parasites, the spatial distribution in Poland, and the variability over time on the basis of specific antibody presence using ELISA and Western blot. Alimentary tract analyses revealed that American mink do not serve as definitive hosts for these parasites. Altogether, 1100 American mink were examined. The average seropositivity for American mink was 14.2% for echinococcosis and 21.7% for toxocarosis; dual-seropositivity was detected in only 6.0%. Seroprevalence of both parasites differed between study sites and significantly increased over time in Toxocara spp. Thus, our study revealed that free-living American mink are exposed to parasites and likely to be involved in the maintenance of both Echinococcus spp. and Toxocara spp. in the wild as paratenic hosts.

Impacts of different altitudes and natural drying times on lipolysis, lipid oxidation and flavour profile of traditional Tibetan yak jerky

The impact of different altitudes on the physicochemical properties, lipolysis, lipid oxidation, volatile compound formation and sensory evaluation of traditional Tibetan dried yak jerky during natural drying was investigated. High altitude (HA) yak jerky showed higher percentages of unsaturated fatty acids and thiobarbituric acid reactive substances than low altitude (LA) yak jerky during natural drying (P < 0.05). The percentages of polyunsaturated fatty acids and monounsaturated fatty acids decreased during natural drying, whereas that of saturated fatty acids increased (P < 0.05). A total of 54 volatile compounds were identified and quantified, and there were higher contents of volatile compounds in HA yak jerky than in LA jerky, which were mainly derived from lipid oxidation. Principal component analysis showed that the volatile compounds associated with the highest overall acceptability in HA yak jerky were hexanal, nonanal, (E)-2-nonenal, 1-hexanol, 2-heptanone, 2-methyl-3-octanone and 6-methyl-5-hepten-2-one. The volatile compounds associated with the highest overall acceptability for yak jerky with a longer natural drying time were hexane, 1-octanol, 2-ethylhexanol, heptanal, (E)-2-hexenal, (E)-2-octenal, 1-octen-3-ol and 2,3-octanedione. According to the sensory evaluations, HA yak jerky with a natural drying time of 75 d tends to be more popular.

Hepatitis E virus in Tibetan pigs on the Qinghai-Tibetan Plateau: detection, molecular characterization and infection of BALB/c mice

This study was performed to investigate the prevalence and genetic variation of hepatitis E virus (HEV) in Tibetan pigs and to determine its ability to infect mice. A total of 38 out of 229 (16.59%; 95% CI = 12.00%-22.10%) fecal samples from Tibetan pigs from the Qinghai-Tibetan Plateau in 2018 were positive for HEV RNA, which was detected by RT-nPCR. Significantly different detection rates were observed between samples from diarrheic and clinically healthy animals (OR = 9.56; 95% CI, 2.84-32.14; p < 0.001), suggesting a potential association between HEV infection and diarrhea in Tibetan pigs. Phylogenetic analysis showed that the HEV isolates were clustered into subtypes 4a (31 samples), 4b (1), 4d (2), and 4j (4). HEV-4a was the predominant subtype, indicating that it might be circulating in Tibetan pigs. Nine complete HEV genome sequences obtained from Tibetan pigs were found by phylogenetic analysis to be closely related to those of genotype 4 HEV isolates from humans. Two recombinant events were identified in both HEV-4a strains; a novel recombination breakpoint was first identified at the 3' end of the ORF2 region in the SWU/L9/2018 strain, and a common recombination region was found at the junction of the ORF1 and ORF2 regions in the SWU/31-12/2018 strain. Furthermore, HEV-4a could be detected in all BALB/c mice that were experimentally infected by gavage and contact exposure. The information presented here about the prevalence and genotype diversity of HEV from Tibetan pigs provides important insights into the epidemic features of HEV on the Qinghai-Tibetan Plateau.

Genetic characterization of Echinococcus isolates from various intermediate hosts in the Qinghai-Tibetan Plateau Area, China

This study examined Echinococcus spp. genotypes and genetic variants isolated from humans as well as domestic and wild animals from the Qinghai-Tibetan Plateau Area using the cox1 gene. All samples except the pika isolates were identified as the Echinococcus granulosus sensu stricto. Sixteen different haplotypes with considerable intraspecific variation were detected and characterized in mitochondrial cox1 sequences. The parsimonious network of cox1 haplotypes showed star-like features, and the neutrality indexes computed via Tajima's D and Fu's Fs tests showed high negative values in E. granulosus s. s., indicating deviations from neutrality; the Fst values were low among the populations, implying that the populations were not genetically differentiated. The pika isolates were identified as E. multilocularis and E. shiquicus. Only one haplotype was recognized in the pika isolates. E. granulosus s. s. was the predominant species found in animals and humans, followed by E. multilocularis and E. shiquicus, with high genetic diversity circulating among the animals and humans in this area. Further studies are needed to cover many sample collection sites and larger numbers of pathogen isolates, which may reveal abundant strains and/or other haplotypes in the hydatid cysts infecting human and animal populations of the QTPA, China.

Sarcosporidiosis: An Emerging Disease in Yaks (Bos grunniens) on the Qinghai Tibetan Plateau (QTP), China

BACKGROUND

Sarcocystosis is a worldwide distributed parasitic zoonosis. However, scarce knowledge is available about the infection of sarcocystosis in yaks.

RESULTS

Herein, we conducted this study to survey the seroprevalence of sarcocystosis in yaks on the Qinghai Tibetan plateau. A total of 2549 serum samples were obtained during 2011-2017, which were assayed using commercial ELISA kits. The results revealed that the overall seroprevalence of sarcosporidiosis in QTP yaks was 0.90% (95 CI 0.6-1.4). The seroprevalence ranged from 0.20% (95 CI 0-1.1) to 1.67% (95 CI 0.8-3.0) in yaks in different areas. The seroprevalence was 0.73% (95 CI 0.3-1.4) in male yaks and 0.06% (95 CI 0.6-1.8) in female yaks. In different ages, the seroprevalence ranged from 0 (95 CI 0-1.4) to 1.47% (95 CI 0.6-3.0). In different years, the seroprevalence ranged from 0 (95 CI 0-1.4) to 1.86% (95 CI 0.7-4.0). In the current study herein, region and age were revealed to be the obvious influencing risk factors by conditional stepwise logistic regression.

DISCUSSION

The current study herein first found the emerging infection of sarcosporidiosis in yaks from high plateaus, which contributes to outline the epidemiological scenario of sarcosporidiosis in yaks in China. Moreover, our findings highlight the urgent need of studies in yaks on the QTP at further and more comprehensive level.

Echinococcosis transmission on the Tibetan Plateau

Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.

Clinico-hematological and oxidative stress status in Nili Ravi buffaloes infected with Trypanosoma evansi

Hemoparasitic diseases like trypanosomiasis have an adverse influence on the health and working capability of infected animals. Monitoring and identification of blood born parasitic infections in dairy animals are of vital importance to get the optimum production. In this study blood samples were collected from Nili Ravi buffaloes (n = 390) kept at different villages of district Lodhran, Punjab province of Pakistan. Blood samples were evaluated for red blood cell counts, total and differential leukocyte counts, hematocrit, hemoglobin, total proteins and different serum parameters such as alanine aminotransferase, aspartate aminotransferase, malondialdehyde, alkaline phosphatase, lactate dehydrogenase, phosphorous, copper, calcium and magnesium. Overall prevalence of Trypanosoma evansi was 4.61% based on microscopic smear examination, 11.02% with Formol Gel Test and 16.15% with PCR. Infected buffaloes showed different clinical signs, including high fever (105 ± 1.0 °F), edema of face and legs, hyperemic mucosa of eyes, lachrymation, bulging eyes, pale mucus membranes and frequent urination. Microscopic examination of blood films showed morphologically different parasites. Statistical analysis did not indicate an association of infection based on age and sex of buffaloes. Results revealed significantly (p < 0.05) lower values of red blood cell counts, hemoglobin, hematocrit, mean corpuscular hemoglobin concentration and total proteins, while increased values of mean corpuscular volume, total white blood cells, monocyte, neutrophils, basophils and eosinophils in infected animals. Infected buffaloes were suffering from macrocytic hypochromic anemia. A significant (p < 0.05) increase in serum lipid per oxidation product (malondialdehyde) level and serum enzymes while a decrease in macrominerals and trace mineral (copper) in trypanosomiasis positive buffaloes were recorded. It was concluded that Trypanosoma evansi is prevalent in Pakistan under tropical and subtropical climatic conditions. It causes clinical disease with macrocytic hypochromic anemia and oxidative stress in infected buffaloes.

Socio-economic burden of parasitic infections in yaks from 1984 to 2017 on Qinghai Tibetan Plateau of China-A review

Yak is an important animal for the Tibetans at Qinghai-Tibetan Plateau of China. The burden of parasitic diseases has been a major threat to the health of yaks at this region presenting a considerable socio-economic losses and impact to yak production and local nomads. Keeping in view, we collected the published papers from 1984 to 2017 on major parasitic infections in yaks by electronic literature search from five databases including CNKI, Google, PubMed, Science Direct and Web of Science. The prevalence of Eimeria, Babesia, Theileria, Hypodermosis, Cystic echinococcosis, Alveolar echinococcosis, Toxoplasma gondii, Neospora caninum, Cryptosporidium, Giardia duodenalis, Enterocytozoon bieneusi, Toxocara vitulorum, and Fascioliasis infection in yaks was found to be 48.02%, 13.06%, 36.11%, 59.85%, 16.93%, 0.99%, 20.50%, 5.14%, 10.00%, 3.68%, 4.07%, 22.23% and 28.7% respectively. Data presented are contemplated to enhance our current understanding on the major parasitic diseases of yaks at Qinghai Tibetan plateau, China. The main aim of this effort is to ameliorate the effects of the parasitic burden in this specie; so that, the attempts are made to minimize the incidence of these infections in future to raise the socio-economic levels of local community.

Characterization of the complete mitochondrial genome of Metastrongylus salmi (M. salmi) derived from Tibetan pigs in Tibet, China

The present study was designed to determine and analyze the mt genomes of Metastrongylus salmi (M. salmi), and reveal the phylogenetic relationships of this parasite using mt DNA sequences. Results showed that the complete mt genome of M. salmi was 13722 bp containing 12 protein-coding genes (cox1-3, nad1-6, nad4L, atp6 and cytb), 22 transfer RNA genes, and 2 ribosomal RNA genes (rrnL and rrnS). The overall A+T content was 73.54% and the nucleotide composition was A (23.52%), C (6.14%), G (19.60%), T (50.02%), and N (UCAG) (0.73%). A total of 4237 amino acids are encoded from the Tibetan isolates of M. salmi mt genomes. The ATA was predicted as the most common starting codon with 41.7% (5/12 protein genes); and 11 of the 12 protein genes were found to have a TAG or TAA translation termination codon. By clustering together the phylogenetic trees of Tibetan M. salmi and Austrian M. salmi, the M. salmi isolated from Tibetan pigs was found to be highly homological with that stemmed from Austrian one. This information provides meaningful insights into the phylogenetic position of the M. salmi China isolate and represents a useful resource for selecting molecular markers for diagnosis and population studies.

Development of sandwich Enzyme-Linked Immunosorbent Assay for the detection of porcine epidemic diarrhea virus in fecal samples

Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea and dehydration in new-born piglets with subsequent economic losses to swine industry. In the current study, gene encoding of 381aa-792aa spike protein (S1) with the main epitope relative to virus neutralization of PEDV was amplified by RT-PCR and inserted into vector pET-30A(+). The plasmid was transferred into Escherichia coli BL21 (DE3). Meanwhile, recombinant protein expression was induced by isopropy1-β-galactopyranoside (IPTG). After denaturation and renaturation of inclusion bodies, the S1 protein was obtained by using purified recombinant S1 protein in immunized female BALB/c mice. Monoclonal antibodies (MAb) against S1 protein, named 4C7 by hybridoma technique were gained successfully. The result showed that MAb can specifically respond to S1 protein and PEDV via ELISA, Western bolt and immunofluorescence assay methods. A sandwich ELISA (S-ELISA) was established by using the captured monoclonal antibodies 4C7. The sensitivity and specificity were compared between S-ELISA and RT-PCR, which showed similar sensitivity and specificity. This work indicated that S-ELISA would be a significant tool alongside a specific diagnostic reagent for PEDV in future.

Characterization of fungus microbial diversity in healthy and diarrheal yaks in Gannan region of Tibet Autonomous Prefecture

Diarrhea is a serious epidemic in yaks on Qinghai Tibet plateau, but the exact pathogen is not confirmed. Diarrhea is related to the changes in diversity of intestinal flora. The current study herein is performed for high-throughput sequencing of fungus microbial diversity in healthy adult yaks, diarrheal adult yaks and diarrheal yak calves in Gannan Tibetan Autonomous Prefecture. A total 446726 optimized sequences were achieved. Over 250 OTUs in species level have been indentified for each sample. The Shannon and Simpson index revealed that there was no visible difference in the flora between different yak groups (p > 0.05). However, obvious difference was watched in the principal component of microbial community structure in different yak groups by PCA analysis, especially between healthy adult yak group and diarrheal adult yak groups. There were 248 fungus species shared in three groups. Interestingly, there were 97 fungus species shared in the diarrheal groups (calves and adult yaks), which were not found in the healthy yaks, while there were 212 fungus species only found in the healthy yaks. In the Phylum level, 1 phylum (Neocallimastigomycota) was discovered to have significant difference between healthy yaks and diarrheal yak calves (p < 0.05). In the genus level, 23 genus were found obvious difference between healthy adult yaks and diarrheal adults yaks (p < 0.05); 28 genus were found significant difference between healthy adult yaks and diarrheal yak calves (p < 0.05); 23 genus were found obvious difference between diarrheal adult yaks and diarrheal yak calves (p < 0.05). The present study herein first reported an insight of the change of microbial diversity of fungus in diarrhea yaks at altitude regions, which contributed towards the solid prevention of diarrhea in yaks.

Equine Granulocytic Anaplasmosis 28 years later

Equine granulocytic anaplasmosis (EGA) is an important tick borne disease of equines that is caused by Anaplasma phagocytophilum (A. phagocytophilum). The etiological agent has veterinary as well as public health importance because of its zoonotic nature. A. phagocytophilum causes an acute illness in equines with loss of appetite, lethargy, hemorrhages and lameness. Clinically, EGA is diagnosed upon examination of morulae within neutrophils especially granulocytes in the blood. The best diagnostic tool for the detection of EGA is Polymerase chain reaction (PCR). Previous studies suggested that EGA is a self-limiting disease and tetracycline therapy is considered as a best treatment regimen. There is no comprehensive summary on the occurrence and distribution of the infection at global level. Therefore, we intended to provide a comprehensive summary on the prevalence and epidemiology of EGA in different areas of the world. It includes mapping the global distribution of EGA in different areas of the world to identify the endemic regions which may be a source of potential disease outbreak. For this purpose, the published data from 1990 to 2018 on EGA was reviewed and collected by electronic literature search of five databases including Google, Google Scholar, Science Direct, PubMed and Web of Science.

Mitochondrial genome data confirm that yaks can serve as the intermediate host of Echinococcus canadensis (G10) on the Tibetan Plateau

Background

Cervids used to be considered the only animal intermediate hosts of the G10 genotype of Echinococcus canadensis. Yaks are often herded in the Qinghai-Tibet Plateau, China, where echinococcosis remains prevalent. However, no E. canadensis G10 cases have been recorded in yaks until now. The aim of our study was to identify causative agents of echinococcosis in yaks in this region.

Methods

Total genomic DNA was extracted from the germinal layer of one hydatid using a Blood and Tissue Kit. Full-length mitochondrial (mt) cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes were amplified by PCR. All purified PCR products were directly sequenced in both directions. Then seven pairs of overlap primers were designed to amplify the entire mt genome sequence of a suspected E. canadensis G10 isolate. Phylogenetic analyses were performed based on concatenated nucleotides from the 12 protein-coding genes of mt genomes of Echinococcus species in a Bayesian framework using MrBayes v3.1 and implementing the GTR + I + G model.

Results

Hydatids were found in yaks (n = 129) when organs were inspected at the slaughterhouse in Maqu county, Gannan Tibetan Autonomous Prefecture, Gansu Province, China in October 2016. Of these, 33 (25.6%) harbored up to a dozen hydatid cysts. One cyst from each yak was characterized by sequencing its mitochondrial (mt) cox1 and nad1 genes. On the basis of these sequence data, 32 cysts were identified as Echinococcus granulosus (sensu stricto) (G1-G3) and the remaining one was identified as the G10 genotype of E. canadensis. Its mt genome was then fully sequenced and compared with that of the G10 genotype in GenBank (AB745463). Phylogenetic analysis using complete mt genomes confirmed the Chinese cyst as belonging to the G10 genotype.

Conclusions

To our knowledge, this is the first report globally of E. canadensis (G10) from yaks in China, which suggests that the G10 genotype has a wider geographical distribution and broader host range than previously believed. This genotype has therefore potential risks to human health and animal husbandry.