Causes of neonatal calf diarrhea and mortality in pasture-based dairy herds in Uruguay: a farm-matched case-control study

Detection and molecular characterization of major enteric pathogens in calves in central Ethiopia

BACKGROUND

Calf diarrhea is a major cause of morbidity and mortality in the livestock sector worldwide and it can be caused by multiple infectious agents. In Ethiopia, cattle are the most economically important species within the livestock sector, but at the same time the young animals suffer from high rates of morbidity and mortality due to calf diarrhea. However, studies including both screening and molecular characterization of bovine enteric pathogens are lacking. Therefore, we aimed to both detect and molecularly characterize four of the major enteric pathogens in calf diarrhea, Enterotoxigenic Escherichia coli (E. coli K99 +), Cryptosporidium spp., rotavirus A (RVA), and bovine coronavirus (BCoV) in calves from central Ethiopia. Diarrheic and non-diarrheic calves were included in the study and fecal samples were analyzed with antigen-ELISA and quantitative real-time PCR (qPCR). Positive samples were further characterized by genotyping PCRs.

RESULTS

All four pathogens were detected in both diarrheic and non-diarrheic calves using qPCR and further characterization showed the presence of three Cryptosporidium species, C. andersoni, C. bovis and C. ryanae. Furthermore, genotyping of RVA-positive samples found a common bovine genotype G10P[11], as well as a more unusual G-type, G24. To our knowledge this is the first detection of the G24 RVA genotype in Ethiopia as well as in Africa. Lastly, investigation of the spike gene revealed two distinct BCoV strains, one classical BCoV strain and one bovine-like CoV strain.

CONCLUSIONS

Our results show that Cryptosporidium spp., E. coli K99 + , RVA and BCoV circulate in calves from central Ethiopia. Furthermore, our findings of the rare RVA G-type G24 and a bovine-like CoV demonstrates the importance of genetic characterization.

Novel CRISPR/Cas13-based assay for detection of bovine coronavirus associated with severe diarrhea in calves

Bovine coronavirus (BCoV) is one of the important causes of diarrhoea in cattle. The virus is responsible for the high fatality rate associated with acute diarrhoea in calves. Rapid and accurate tests need to be conducted to detect the virus and minimise economic losses associated with the disease. Nucleic acid-based detection assays including PCR is an accurate test for detecting pathogens. However, these tests need skilled personnel, time and expensive devices. In this study, we developed a novel assay for the detection of BCoV in clinical cases. This novel assay combined reverse transcription-recombinase polymerase amplification with CRISPR/Cas13 and conducted a rapid visualisation of cleavage activity using a Lateral Flow Device. A conserved sequence of the BCV M gene was used as a target gene and the assays were tested in terms of specificity, sensitivity and time consumption. The result showed the specificity of the assay as 100% with no false positives being detected. Ten copies of the input RNA were enough to detect the virus and perform the assay. It took up to forty minutes for reading the results. Conducted together, the assay should be used as a rapid test to clinically diagnose infectious pathogens including bovine coronavirus. However, the assay needed the RNA to be extracted from the clinical sample in order to detect the virus. Therefore, more studies are needed to optimise the assay to be able to detect the virus in the clinical sample without extracting the RNA.

Experimental oral administration of pollen beetle (Astylus atromaculatus) to cattle results in an acute lethal gastrointestinal disease

In the summer of 2023, ingestion of Astylus atromaculatus (pollen beetle) was linked to spontaneous fatal disease in grazing cattle and sheep in Argentina and Uruguay. While the disease was experimentally reproduced in sheep and guinea pigs in the 1970's, no experimental reproductions have been attempted in cattle, and controversy exists as to whether this insect is indeed noxious to cattle and at which dose. Here, we demonstrate that A. atromaculatus causes acute fatal disease in Hereford calves at single oral dosages of 2.5, 4.5, 10.0, and 15.0 g of insect/kg body weight. Death or severe disease necessitating euthanasia occurred at 38 to 48 hours postinoculation regardless of the dose, suggesting that the single fatal dosage is likely <2.5 g/kg body weight (this dose representing approximately 850 mL of intact beetles in a 100 kg calf). Clinically, the disease was characterized by acute anorexia, prolonged recumbency, reluctance to move, listlessness/apathy, depression, ruminal hypomotility and tympany, hypothermia, bruxism with frothing at the mouth, and mucoid diarrhea progressing to death. Hematologic and biochemical alterations included hemoconcentration, stress/acute inflammatory leukogram, negative energy balance, and ketosis. The pathological hallmark of this experimental disease is acute necrotizing omaso-reticulo-rumenitis, fibrinohemorrhagic enteritis, and exfoliative colitis with intralesional chitinous insect fragments. While A. atromaculatus might contain a gastrointestinal toxin or pathogen, extensive toxicological testing failed to identify a causative toxin. Other pathomechanisms such as direct physical damage caused by insect fragments on the alimentary tract seem plausible, although further studies are needed to elucidate the pathogenesis of A. atromaculatus-associated disease.

Comparison of Antibiotic Use and the Frequency of Diseases Depending on the Size of Herd and the Type of Cattle Breeding

Diseases are responsible for losses in livestock production by increasing animal mortality and reducing productivity. The administration of antibiotics can help mitigate these negative effects. However, inappropriate use can lead to severe complications, such as raising antibiotic resistance. The purpose of this study was to perform a comparative analysis of antibiotic use and disease frequency over four years, based on the size of dairy farms and the type of farm. The study covered a 4-year period and included medium dairy farms (20-50 cows, n = 13), large dairy farms (>250 cows, n = 8), and large beef farms (n = 8). The collected data involved antimicrobial use but also included farm demographics, animal health, disease frequency, and herd management practices. The criteria used to categorise antibiotics into groups A-D were based on the EMA guidelines. The carried-out study showed that the large dairy cattle farms had the highest antibiotic consumption (18.29 mg·PCU-1), due to the high frequency of diseases, and consequently, the treatment of calf (diarrhoea, lung inflammations) and cow diseases (general treatment and mastitis). Cattle on large beef farms suffer mainly from general diseases caused by maintenance and herd management conditions. The use of restrict antibiotics was, in some cases, unjustified (antibiotics for dry cow therapy). Future studies should consider a larger number of farms, taking into account the given direction of cattle production.

Unveiling genetic signatures associated with resilience to neonatal diarrhea in lambs through two GWAS approaches

Neonatal diarrhea presents a significant global challenge due to its multifactorial etiology, resulting in high morbidity and mortality rates, and substantial economic losses. While molecular-level studies on genetic resilience/susceptibility to neonatal diarrhea in farm animals are scarce, prior observations indicate promising research directions. Thus, the present study utilizes two genome-wide association approaches, pKWmEB and MLM, to explore potential links between genetic variations in innate immunity and neonatal diarrhea in Karacabey Merino lambs. Analyzing 707 lambs, including 180 cases and 527 controls, revealed an overall prevalence rate of 25.5%. The pKWmEB analysis identified 13 significant SNPs exceeding the threshold of ≥ LOD 3. Moreover, MLM detected one SNP (s61781.1) in the SLC22A8 gene (p-value, 1.85eE-7), which was co-detected by both methods. A McNemar's test was conducted as the final assessment to identify whether there are any major effective markers among the detected SNPs. Results indicate that four markers-oar3_OAR1_122352257, OAR17_77709936.1, oar3_OAR18_17278638, and s61781.1-have a substantial impact on neonatal diarrhea prevalence (odds ratio: 2.03 to 3.10; statistical power: 0.88 to 0.99). Therefore, we propose the annotated genes harboring three of the associated markers, TIAM1, YDJC, and SLC22A8, as candidate major genes for selective breeding against neonatal diarrhea.

Detection and Genetic Characterization of Bovine Torovirus in Uruguay

Bovine torovirus (BToV) is an enteric pathogen that may cause diarrhea in calves and adult cattle, which could result in economic losses due to weight loss and decreased milk production. This study aimed to report the presence, the genetic characterization and the evolution of BToV in calves in Uruguay. BToV was detected in 7.9% (22/278) of fecal samples, being identified in dairy (9.2%, 22/239) but not beef (0.0%, 0/39) calves. BToV was detected in both diarrheic (14%, 6/43) and non-diarrheic (13.2%, 5/38) dairy calves. In addition, BToV was detected in the intestinal contents of 14.9% (7/47) of naturally deceased dairy calves. A complete genome (28,446 nucleotides) was obtained, which was the second outside Asia and the first in Latin America. In addition, partial S gene sequences were obtained to perform evolutionary analyses. Nucleotide and amino acid substitutions within and between outbreaks/farms were observed, alerting the continuous evolution of the virus. Through Bayesian analysis using BEAST, a recent origin (mid-60s) of BToV, possibly in Asia, was estimated, with two introductions into Uruguay from Asia and Europe in 2004 and 2013, respectively. The estimated evolutionary rate was 1.80 × 10-3 substitutions/site/year. Our findings emphasize the importance of continued surveillance and genetic characterization for the effective management and understanding of BToV's global epidemiology and evolution.

Microscopic, Molecular and Antigen Detection and Isolation of Cryptosporidium parvumParasites in Diarrheal Disease of Calves in Iran

Cryptosporidiosis is a parasitic disease caused by the protozoan Cryptosporidium in vertebrates. In livestock, especially ruminants, infants develop diarrheal syndromes. The infection is common worldwide , including Iran, where it is reported in several species. Morphological diagnosis of Cryptosporidium species is associated with many limitations and has no taxonomic value on its own, so the use of molecular methods can overcome these limitations to some extent. The present aims at microscopic, molecular and antigen detection and isolation of Cryptosporidium parvum parasites. Firstly, 300 samples were collected from different parts of Iran. Subsequently oocysts from feces were purified by the method of Casemore et al. using the flotation technique and stained by the modified Ziehl-Neelsen method (Henriksen method) and identified by diagnostic keys. ELISA test was also performed on the samples with results ranging from 1 to 4 positive. The results of our study show that, of the 300 cases tested for Cryptosporidium, 48 cases (16%) and 54 (18%) were positive in ELISA and PCR, respectively. Microscopic evaluation also mainly confirmed the ELISA results. These cases were collected in summer, autumn, and winter, with, more than 50% of the positive cases found among the samples collected in autumn. In addition, 54 positive cases were found by PCR test, which is 6 cases more than ELISA results. Finally, the results of PCR detection and ELISA were subjected to chi-square analysis, where no significant difference was found between the collected data (p=0.0587).

Forensic investigations of suspected livestock depredation by vultures: scientific tools for compensation programmes

Human-wildlife conflicts may have devastating consequences for fauna due to targeting by humans of wildlife populations suspected to have predated livestock. Suspicion of depredation of extensively raised livestock by vultures in Europe has triggered public administration-led forensic investigations intended to distinguish between predation and scavenging in order to compensate farmers for attacks on their livestock. In this study, gross and histological analyses were carried out on suspected cases of domestic animal depredation by griffon vultures (Gyps fulvus) over a 1-year period. Fifty-eight animals were affected (n = 41, suspected depredation), including domestic cattle (75.9%), sheep (22.4%) and a goat (1.7%). All the adults affected were female and most cases of suspected depredation occurred during the peripartum period (56%). Histological investigations distinguished between post-mortem (84% of diagnostic samples) and ante-mortem (16% of diagnostic samples) cases, and gross examinations revealed significant differences (P ≤ 0.002) between ante-mortem, post-mortem and non-diagnostic samples. This study highlights the need to optimize sampling protocols to increase the success of forensic studies. The forensic investigations presented here may be applied to resolve human-wildlife conflicts involving not only vultures but other endangered carnivores and contribute to human-wildlife coexistence in rural areas by protecting the interests of both the livestock sector and endangered species.

Molecular Epidemiology of Rotavirus A in Calves: Evolutionary Analysis of a Bovine G8P[11] Strain and Spatio-Temporal Dynamics of G6 Lineages in the Americas

Rotavirus A (RVA) causes diarrhea in calves and frequently possesses the G6 and P[5]/P[11] genotypes, whereas G8 is less common. We aimed to compare RVA infections and G/P genotypes in beef and dairy calves from major livestock regions of Argentina, elucidate the evolutionary origin of a G8 strain and analyze the G8 lineages, infer the phylogenetic relationship of RVA field strains, and investigate the evolution and spatio-temporal dynamics of the main G6 lineages in American countries. Fecal samples (n = 422) from diarrheic (beef, 104; dairy, 137) and non-diarrheic (beef, 78; dairy, 103) calves were analyzed by ELISA and semi-nested multiplex RT-PCR. Sequencing, phylogenetic, phylodynamic, and phylogeographic analyses were performed. RVA infections were more frequent in beef (22.0%) than in dairy (14.2%) calves. Prevalent genotypes and G6 lineages were G6(IV)P[5] in beef (90.9%) and G6(III)P[11] (41.2%) or mixed genotypes (23.5%) in dairy calves. The only G8 strain was phylogenetically related to bovine and artiodactyl bovine-like strains. Re-analyses inside the G8 genotype identified G8(I) to G8(VIII) lineages. Of all G6 strains characterized, the G6(IV)P[5](I) strains from "Cuenca del Salado" (Argentina) and Uruguay clustered together. According to farm location, a clustering pattern for G6(IV)P[5] strains of beef farms was observed. Both G6 lineage strains together revealed an evolutionary rate of 1.24 × 10-3 substitutions/site/year, and the time to the most recent common ancestor was dated in 1853. The most probable ancestral locations were Argentina in 1981 for G6(III) strains and the USA in 1940 for G6(IV) strains. The highest migration rates for both G6 lineages together were from Argentina to Brazil and Uruguay. Altogether, the epidemiology, genetic diversity, and phylogeny of RVA in calves can differ according to the production system and farm location. We provide novel knowledge about the evolutionary origin of a bovine G8P[11] strain. Finally, bovine G6 strains from American countries would have originated in the USA nearly a century before its first description.

Blood metabolomics reveals the therapeutic effect of Pueraria polysaccharide on calf diarrhea

BACKGROUND

Neonatal calf diarrhea (NCD) is typically treated with antibiotics, while long-term application of antibiotics induces drug resistance and antibiotic residues, ultimately decreasing feed efficiency. Pueraria polysaccharide (PPL) is a versatile antimicrobial, immunomodulatory, and antioxidative compound. This study aimed to compare the therapeutic efficacy of different doses of PPL (0.2, 0.4, 0.8 g/kg body weight (BW)) and explore the effect of plasma metabolites in diarrheal calves by the best dose of PPL.

RESULTS

PPL could effectively improve the daily weight gain, fecal score, and dehydration score, and the dosage of 0.4 g/kg BW could reach curative efficacy against calf diarrhea (with effective rates 100.00%). Metabolomic analysis suggested that diarrhea mainly affect the levels of taurocholate, DL-lactate, LysoPCs, and intestinal flora-related metabolites, trimethylamine N-oxide; however, PPL improved liver function and intestinal barrier integrity by modulating the levels of DL-lactate, LysoPC (18:0/0:0) and bilirubin, which eventually attenuated neonatal calf diarrhea. It also suggested that the therapeutic effect of PPL is related to those differential metabolites in diarrheal calves.

CONCLUSIONS

The results showed that 0.4 g/kg BW PPL could restore the clinical score of diarrhea calves by improving the blood indexes, biochemical indexes, and blood metabolites. And it is a potential medicine for the treatment of calf diarrhea.

Effect of synbiotics on growth performance, gut health, and immunity status in pre-ruminant buffalo calves

Synbiotics are employed as feed additives in animal production as an alternate to antibiotics for sustaining the gut microbiota and providing protection against infections. Dairy calves require a healthy diet and management to ensure a better future for the herd of dairy animals. Therefore, the present study was carried out to investigate the effect of synbiotics formulation on growth performance, nutrient digestibility, fecal bacterial count, metabolites, immunoglobulins, blood parameters, antioxidant enzymes and immune response of pre-ruminant Murrah buffalo calves. Twenty-four apparently healthy calves (5 days old) were allotted into four groups of six calves each. Group I (control) calves were fed a basal diet of milk, calf starter and berseem with no supplements. Group II (SYN1) calves were fed with 3 g fructooligosaccharide (FOS) + Lactobacillus plantarum CRD-7 (150 ml). Group III (SYN2) calves were fed with 6 g FOS + L. plantarum CRD-7 (100 ml), whereas calves in group IV (SYN3) received 9 g FOS + L. plantarum CRD-7 (50 ml). The results showed that SYN2 had the highest (P < 0.05) crude protein digestibility and average daily gain compared to the control. Fecal counts of Lactobacilli and Bifidobacterium were also increased (P < 0.05) in supplemented groups as compared to control. Fecal ammonia, diarrhea incidence and fecal scores were reduced in treated groups while lactate, volatile fatty acids and antioxidant enzymes were improved compared to the control. Synbiotic supplementation also improved both cell-mediated and humoral immune responses in buffalo calves. These findings indicated that synbiotics formulation of 6 g FOS + L. plantarum CRD-7 in dairy calves improved digestibility, antioxidant enzymes, and immune status, as well as modulated the fecal microbiota and decreased diarrhea incidence. Therefore, synbiotics formulation can be recommended for commercial use in order to achieve sustainable animal production.

Epidemiological and clinicopathological findings in 15 fatal outbreaks of salmonellosis in dairy calves and virulence genes in the causative Salmonella enterica Typhimurium and Dublin strains

Salmonella enterica is a major food-borne pathogen that affects cattle-rearing systems worldwide. Little information is available on the epidemiology and pathology of salmonellosis and the virulence genes (VGs) carried by Salmonella in spontaneous outbreaks in cattle. We describe epidemiological findings in 15 fatal outbreaks of salmonellosis in Uruguayan dairy farms and the age, clinical signs, and pathology in 20 affected calves. We also describe the serotypes and frequencies of 17 VGs in the causative Salmonella strains and explore their associations with epidemiological, clinical, and pathological findings. Salmonella Typhimurium and Dublin were identified in 11/15 and 4/15 outbreaks, respectively. The most frequent reason for consultation was digestive disease (8 outbreaks caused by S. Typhimurium), followed by sudden death (4 outbreaks, 3 caused by S. Dublin). Morbidity, mortality, and lethality ranged 4.8-100%, 3.8-78.9%, and 10-100%, without significant differences between serotypes. Diarrhea, the most common clinical sign (14 cases), was associated with the Typhimurium serotype (OR = 26.95), especially in ≤ 30-day-old calves with fibrinous enteritis as the main autopsy finding. The Dublin serotype affected ≥ 50-day-old calves and was associated with fibrinosuppurative splenitis (p = 0.01) and tubulointerstitial nephritis (OR = 48.95). The chances of the Dublin serotype increased significantly with age. There was low variability of VG across serotypes. The pefA gene was associated with the Typhimurium serotype (OR = 21.95), macroscopic enteritis (p = 0.03), and microscopic fibrinosuppurative splenitis (p = 0.04). Understanding the epidemiology, pathology, and virulence of S. enterica at the farm level is key to delineating prevention and control strategies to mitigate its impact on animal and human health.

Prevalence of bovine viral diarrhea virus in cattle between 2010 and 2021: A global systematic review and meta-analysis

Background

Bovine viral diarrhea is one of the diseases that cause huge economic losses in animal husbandry. Many countries or regions have successively introduced eradication plans, but BVDV still has a high prevalence in the world. This meta-analysis aims to investigate the prevalence and risk factors of BVDV in the world in recent 10 years, and is expected to provide some reference and theoretical basis for BVDV control plans in different regions.

Method

Relevant articles published from 2010 to 2021 were mainly retrieved from NCBI, ScienceDirect, Chongqing VIP, Chinese web of knowledge (CNKI), web of science and Wanfang databases.

Results

128 data were used to analyze the prevalence of BVDV from 2010 to 2021. BVDV antigen prevalence rate is 15.74% (95% CI: 11.35-20.68), antibody prevalence rate is 42.77% (95% CI: 37.01-48.63). In the two databases of antigen and antibody, regions, sampling time, samples, detection methods, species, health status, age, sex, breeding mode, and seasonal subgroups were discussed and analyzed, respectively. In the antigen database, the prevalence of dairy cows in the breed subgroup, ELISA in the detection method subgroup, ear tissue in the sample subgroup, and extensive breeding in the breeding mode were the lowest, with significant differences. In the antibody database, the prevalence rate of dairy cows in the breed subgroup and intensive farming was the highest, with a significant difference. The subgroups in the remaining two databases were not significantly different.

Conclusion

This meta-analysis determined the prevalence of BVDV in global cattle herds from 2010 to 2021. The prevalence of BVDV varies from region to region, and the situation is still not optimistic. In daily feeding, we should pay attention to the rigorous and comprehensive management to minimize the spread of virus. The government should enforce BVDV prevention and control, implement control or eradication policies according to local conditions, and adjust the policies in time.

Detection of the dominant pathogens in diarrheal calves of Ningxia, China in 2021-2022

Introduction

Calf diarrhea is a complex disease that has long been an unsolved problem in the cattle industry. Ningxia is at the forefront of China in the scale of cattle breeding, and calf diarrhea gravely restricts the development of Ningxia's cattle industry.

Methods

From July 2021 to May 2022, we collected diarrhea stool samples from calves aged 1-103 days from 23 farms in five cities in Ningxia, and performed PCR using specific primers for 15 major reported pathogens of calf diarrhea, including bacteria, viruses, and parasites. The effect of different seasons on the occurrence of diarrhea in calves was explored, the respective epidemic pathogens in different seasons were screened, and more detailed epidemiological investigations were carried out in Yinchuan and Wuzhong. In addition, we analyzed the relationship between different ages, river distributions and pathogen prevalence.

Results

Eventually, 10 pathogens were detected, of which 9 pathogens were pathogenic and 1 pathogen was non-pathogenic. The pathogens with the highest detection rate were Cryptosporidium (50.46%), Bovine rotavirus (BRV) (23.18%), Escherichia coli (E. coli) K99 (20.00%), and Bovine coronavirus (BCoV) (11.82%). The remaining pathogens such as Coccidia (6.90%), Bovine Astrovirus (BoAstV) (5.46%), Bovine Torovirus (BToV) (4.09%), and Bovine Kobuvirus (BKoV) (3.18%) primarily existed in the form of mixed infection.

Discussion

The analysis showed that different cities in Ningxia have different pathogens responsible for diarrhea, with Cryptosporidium and BRV being the most important pathogens responsible for diarrhea in calves in all cities. Control measures against those pathogens should be enforced to effectively prevent diarrhea in calves in China.

Occurrence of Escherichia coli Pathotypes in Diarrheic Calves in a Low-Income Setting

Different E. coli pathotypes are common zoonotic agents. Some of these pathotypes cause recurrent and widespread calf diarrhea and contribute to significant economic losses in the livestock sector worldwide in addition to putting humans at risk. Here, we investigated the occurrence of E. coli pathotypes in diarrheic calves in Ethiopia kept under various calf management practices. One hundred fecal samples were collected from diarrheic calves in 98 different farms. E. coli was isolated in the samples from 99 of the diarrheic calves, and virulence genes were detected in 80% of the samples. The occurrence of E. coli pathotypes in the samples was 32% ETEC, 23% STEC, 18% STEC/ETEC, 3% EPEC, 2% EAEC, and 1% EHEC. No diarrheic calves were positive for the EIEC and DAEC pathotypes. The occurrence of pathotypes was positively associated with female calves (EPEC, p = 0.006), aged less than 2 weeks (STEC, p = 0.059), and calves fed colostrum via the hand method (STEC, p = 0.008 and EAEC, p = 0.003). This study revealed that several E. coli pathotypes occurred among calves affected with diarrhea. Moreover, the presence of a mixed STEC/ETEC pathotypes infection was present in the studied low-income setting. These findings indicate a considerable risk for the zoonotic transmission from calves to humans and the options to provide the better management for younger calves in order to reduce the economic loss.

Common diseases of cattle in Jordan: A retrospective study (2015-2021)

Background and Aim

In many developing countries, infectious and non-infectious diseases remain a major hurdle in achieving satisfactory status related to animal health, productivity, and welfare. In Jordan, there are no comprehensive reports describing the most common diseases involving different body systems in different age groups of cattle. Therefore, this retrospective study was designed to report the frequencies of various infectious and non-infectious diseases and their distribution according to sex, age, and body system in cattle in Jordan.

Materials and Methods

Case medical records of cattle presented for clinical evaluation to the Veterinary Health Center of the Faculty of Veterinary Medicine at Jordan University of Science and Technology between January 2015 and December 2021 were used in this study. The data were categorized based on sex (female vs. male), body system involved in the disease process, nature of the disease process (infectious vs. non-infectious), and age (pre-weaning [<2 months of age], 2 months-2 years of age, and older than 2 years of age). Descriptive analysis was performed to report the frequencies, averages, and range values using Excel spreadsheets.

Results

Medical records of 513 cattle cases were used in the study. All cattle belonged to the Holstein-Friesian dairy breed. The majority of cases were female (91%). The age of animals ranged between 1 day and 8 years. According to age groups, there were 52%, 27%, and 16% of cases older than 2 years, 2 months-2 years, and pre-weaning (<2 months), respectively. Among males and females, the majority of cases were diagnosed with gastrointestinal diseases (30%), followed by udder/teat diseases (18%), reproductive and obstetrical diseases (16%), and respiratory diseases (11%). Other body systems involved in disease processes were metabolic (7%), musculoskeletal (6%), cardiovascular/circulatory (4%), multiple systems (3%), nervous (2%), ear/eye (2%), and skin (1%).

Conclusion

Results of this study provide valuable information on the most likely diagnostic list of diseases involving various body systems of different age groups in cattle in Jordan. This information could serve as a clinical guideline for field diagnosis of cattle diseases and provide an accurate estimate of the current status of cattle welfare, health, and husbandry practices in Jordan.

Causes of Mortality of Dairy Cattle Diagnosed by Complete Necropsy

Simple Summary

Necropsy of dairy cattle is an important diagnostic tool, often more definitive or differing from the perceptions of dairy farm personnel in diagnosing the cause of death. This retrospective case series summarized the primary causes of death in all dairy animals diagnosed at necropsy from Utah and other states, mostly in the Intermountain West of the U.S. Some fatal diseases in dairy cattle that might be expected to be diagnosed ante-mortem were detected. Necropsy diagnosis is a guide to changes in management or preventive practices to reduce the rate of deaths in dairy herds.

Abstract

This retrospective case series summarized the primary causes of death in 857 dairy cattle necropsied from 2008 to 2019 at the Utah Veterinary Diagnostic Laboratory, from dairy farms in Utah (76%), Idaho (16%) or other states (8%), primarily in the U.S. Intermountain West. Of cattle with age provided, 74% matched with body weight based estimates for those with no age stated. Cattle ranged from fetuses at 60 days of gestation to 9 years old. Primary cause of mortality was diagnosed in 833 cattle (97%); no cause was evident in 24 cattle (3%). Sexes were female 620 (72%), male 214 (25%), not recorded 23 (3%). Seven diseases killed 80% of the animals: gastrointestinal disease (most enteritis/colitis) 318 (37%); pneumonia 166 (19%); abortion 96 (11%), peritonitis 30 (4%), omphalophlebitis (navel ill) 27 (3%), abomasitis 23 (3%), and metritis 23 (3%). Etiologic agents and specific causes varied with age categories of the animals. Young calves that died from dystocia, omphalophlebitis, or congenital abnormality often presented with no suspicion of those causes by the owners because of no external signs. Some important fatal diseases of adult dairy cows that are often diagnosed ante-mortem were diagnosed at necropsy with no suspicion by those submitting the carcasses: metritis, hardware disease, and displaced abomasum. Multicentric lymphoma was a relatively important cause of death in cows more than 4 years old. Despite use of a toxicology laboratory, toxicity was only diagnosed as causing 1% of the deaths across all ages of dairy cattle. There were numerous other causes of mortality diagnosed as well. Necropsy is a vital tool to diagnose causes of death in dairy cattle and can guide changes in management or preventive practices to reduce the rate of deaths in dairy herds.

Differential proteomic of plasma provides a new perspective on scientific diagnosis and drug screening for dampness heat diarrhea in calves

Dampness heat diarrhea (DHD) is one of the most common syndromes of calf diarrhea. Its complex etiology and lack of objective diagnostic criteria bring great challenges to the diagnosis and treatment of this disease. This study aims to screen some prospective diagnostic biomarkers or therapeutic targets for calves with DHD by investigating the differential protein profiles of plasma between DHD calves and clinically healthy calves by mass spectrometry-based proteomic. A total of 120 DHD calves and 90 clinically healthy calves were divided into two groups randomly, 30 DHD calves and 30 clinically healthy calves in the test group, and 90 DHD calves and 60 clinically healthy calves in the validation group. In the test group, a total of 52 proteins were differentially expressed between calves with DHD and clinically healthy calves, 13 proteins were significantly increased and 39 proteins were significantly decreased. The differentially expressed proteins were associated with the intestinal immune network of IgA production, caffeine metabolism, purine metabolism, and PI3K signaling pathway. In the validation group, 13 proteins were selected from 52 differential expression proteins for parallel reaction monitoring validation to verify their associations with DHD calves. The targeted proteomic results showed that fibronectin precursor (FN1) and apolipoprotein C-IV precursor (APOC4) were significantly associated with DHD in calves, and they were downregulated in sick calves. In conclusion, the differential expression of plasma proteins was associated with DHD pathogenesis in calves, and the FN1 and APOC4 might be the potential clinical biomarkers for diagnosis of DHD in calves, and the intestinal immune network of IgA production, caffeine metabolism, purine metabolism, and PI3K signaling pathway are the candidate targets to treat DHD in calves. Our finding provides a reference for further investigating the pathogenesis, developing techniques of diagnosis, and screening treatment drugs for DHD in calves.

Prevalence of bovine rotavirus among cattle in mainland China: A meta-analysis

BACKGROUND

Bovine rotavirus is the primary pathogen causing diarrhea in cattle and can be transmitted vertically through the placenta. It mainly presents with clinical signs such as depression, loss of appetite, diarrhea, vomiting, and dehydration.

METHODS

A systematic review and meta-analysis were conducted to assess the prevalence of BRV infection in mainland China. We conducted a literature search on the prevalence of BRV infection in pigs between Jan 1, 1979 and Dec 31, 2021 in English and Chinese databases, including PubMed, Google Scholar, Cochrane library, Clinical Trials, VIP, CNKI, and WanFang database. Selections were made based on the title and the abstract of the paper, Search strings included if they reported the cattle samples of more than 15 cattle and provided information that allowed us to establish the prevalence of BRV. Moreover, we excluded repeated studies, reviews, other hosts. Finally, we extracted the number of cattle with BRV infection from the obtained studies and provided information that permitted us to estimate the prevalence of BRV infection in cattle in mainland China.

RESULTS

The data of 29 articles (including data on 10677 cattle) are compliant with the standards. The pooled prevalence of BRV in cattle in China was 46%（6635/10677）, the pooled prevalence of BRV in cattle from Northeast China (40%) was significantly lower than those from other regions. In addition, the prevalence of BRV was associated with publication time of paper, detection methods, age of cattle, and clinical symptoms（diarrhea, etc.).

CONCLUSION

Our findings suggest that BRV infection is common among cattle in China. It is, therefore, necessary to carry out further research and monitor the prevalence of BRV infection. Furthermore, powerful and effective regulatory measures should be taken to prevent the transmission and spread of BRV among cattle populations.

Determination of an RT-qPCR viral load cutoff point for the etiologic diagnosis of rotavirus A diarrhea in neonate dairy calves

Rotavirus A (RVA) is amongst the most widespread causes of neonatal calf diarrhea. Because subclinical infections are common, the diagnosis of RVA-induced diarrhea cannot rely solely on molecular viral detection. However, RT-qPCR allows for quantification of RVA shedding in feces, which can be correlated with clinical disease. Here, we determine an optimal cutoff of rotaviral load quantified by RT-qPCR to predict RVA causality in diarrheic neonate calves, using RVA antigen-capture ELISA as reference test. Feces from 328 diarrheic (n = 175) and non-diarrheic (n = 153), <30-day-old dairy calves that had been tested by ELISA and tested positive by RT-qPCR were included. Of 82/328 (25.0%) ELISA-positive calves, 53/175 (30.3%) were diarrheic, whereas 124/153 (81.0%) non-diarrheic calves tested negative by ELISA. The median log10 viral load was significantly higher in diarrheic vs. non-diarrheic and ELISA-positive vs. -negative calves, indicating a higher viral load in diarrheic and ELISA-positive calves. A receiver operating characteristic (ROC) analysis was conducted using the viral loads of the 175 diarrheic calves that had tested either positive (n = 53, cases) or negative (n = 122, controls) by ELISA. The optimal log10 viral load cutoff that predicted RVA causality in diarrheic calves was 9.171. A bootstrapping procedure was performed to assess the out-of-bag performance of this cutoff point, resulting in sensitivity = 0.812, specificity = 0.886, area under the curve = 0.922, and positive and negative diagnostic likelihood ratios of 11.184 and 0.142, respectively. The diagnostic accuracy of the cutoff was excellent to outstanding. This information will help in the interpretation of RVA RT-qPCR results in feces of diarrheic calves submitted for laboratory testing.

Distribution of ESBL/AmpC-Escherichia coli on a Dairy Farm

The aim of the study was to determine the prevalence of ESBL/AmpC-producing Escherichia (E.) coli and to investigate their on-farm distribution on an exemplary dairy farm. For this purpose, sample sizes were calculated, and fecal samples were collected from cattle of all ages and analyzed for the presence of ESBL/AmpC-E. coli using selective media supplemented with cefotaxime. These antibiotic-resistant bacteria were detected in 22.5% of the samples tested. The prevalence was highest in the calf age group, in which 100% of the collected fecal samples were positive. With increasing age, the prevalence decreased in the other sample groups. While ESBL/AmpC E. coli could still be detected in young stock (15%) and breeding heifers (5%), no resistant pathogens could be detected in adult animals. Whole-genome sequencing of the ESBL/AmpC-E. coli isolates revealed, first, that all isolates were ESBL producers (CTX-M-1 and CTX-M-15) and, second, that ST362, which is known as a biofilm producer, was dominant in the calves (85%, n = 17). Based on these results and the evaluation of a questionnaire, possible causes for the occurrence of ESBL/AmpC-E. coli were discussed and recommendations for the reduction in transmission were formulated. Unlike most German dairy farms, no waste milk feeding was apparent; therefore, factors reducing ESBL/AmpC-E. coli are primarily related to an improvement in hygiene management to prevent biofilms, e.g., in nipple buckets, but also to question the use of antibiotics, e.g., in the treatment of diarrheic calves.

Huang Bai Jian Pi decoction alleviates diarrhea and represses inflammatory injury via PI3K/Akt/NF-κB pathway: In vivo and in vitro studies

ETHNOPHARMACOLOGICAL RELEVANCE

Huang Bai Jian Pi (HBJP) decoction, a Chinese herbal formula based on the Pulsatilla decoction (PD) and Si Junzi decoction, is efficacy to treat clinical diarrhea in calves.

AIM OF THE STUDY

The mechanism of HBJP decoction to treat calf diarrhea remains unclear. This study was to investigate the therapeutic effect and anti-inflammatory mechanism of HBJP decoction on diarrhea in rats.

MATERIALS AND METHODS

Thirty-six Sprague Dawley rats were randomly divided into control group, model group, PD group and three treated groups with HBJP decoction. The diarrheal model in rats was established by multiple factors including high-sugar and fat diet, high temperature and dampness environment, biological pathogenic factors. The diarrheal animals were treated with HBJP decoction or PD for 5 days. The inflammatory model of the intestinal epithelioid cell line 6 (IEC-6) was induced by TNF-α. The clinical symptoms, blood routine and biochemistry parameters, histopathology of main organs were detected. The proteins associated with PI3K/Akt/NF-κB pathway and the expression levels of cytokines associated with inflammation were detected in vivo and in vitro by Western blot and ELISA.

RESULTS

The model rats showed obvious diarrheal symptoms, and the obvious systemic inflammatory response accompanied with abnormal change in blood routine, biochemistry parameters and histopathology. HBJP decoction alleviated obviously the clinical symptoms, and pathological changes of the liver, colon and lung, and abnormal blood routine and biochemistry indexes in rats. The expression of P-PI3K, P-Akt, P-NF-κB, IL-1β, IL-6 was significantly increased, and the expression of IL-10 was markedly decreased in diarrheal rats and IEC-6 with inflammation. HBJP decoction significantly inhibited the PI3K/AKT/NF-κB signal pathway and adjusted the expression of these inflammatory cytokines.

CONCLUSIONS

The finding suggested that HBJP decoction alleviate the inflammation in diarrhea through inhibiting the PI3K/Akt/NF-κB signal pathway, which provides scientific evidences for the clinical application of HBJP decoction in diarrhea.

Describing and Characterizing the Literature Regarding Umbilical Health in Intensively Raised Cattle: A Scoping Review

The objective of this scoping review was to describe and characterize the existing literature regarding umbilical health and identify gaps in knowledge. Six databases were searched for studies examining umbilical health in an intensively raised cattle population. There were 4249 articles initially identified; from these, 723 full text articles were then screened, with 150 articles included in the review. Studies were conducted in the USA (n = 41), Brazil (n = 24), Canada (n = 13), UK (n = 10), and 37 additional countries. Seventeen were classified as descriptive, 24 were clinical trials, and 109 were analytical observational studies. Umbilical outcomes evaluated in descriptive studies were infection (n = 11), parasitic infection (n = 5), and hernias (n = 2). Of the clinical trials, only one examined treatment of navel infections; the remainder evaluated preventative management factors for navel health outcomes (including infections (n = 17), myiasis (n = 3), measurements (n = 5), hernias (n = 1), and edema (n = 1)). Analytical observational studies examined risk factors for umbilical health (n = 60) and umbilical health as a risk factor (n = 60). Studies examining risk factors for umbilical health included navel health outcomes of infections (n = 28; 11 of which were not further defined), hernias (n = 8), scoring the navel sheath/flap size (n = 16), myiasis (n = 2), and measurements (n = 6). Studies examining umbilical health as a risk factor defined these risk factors as infection (n = 39; of which 13 were not further defined), hernias (n = 8; of which 4 were not further defined), navel dipping (n = 12), navel/sheath scores as part of conformation classification for breeding (n = 2), measurements (n = 3), and umbilical cord drying times (n = 2). This review highlights the areas in need of future umbilical health research such as clinical trials evaluating the efficacy of different treatments for umbilical infection. It also emphasizes the importance for future studies to clearly define umbilical health outcomes of interest, and consider standardization of these measures, including time at risk.

Bovine Astrovirus—A Comprehensive Review

Bovine astrovirus (BoAstV) is a small non-enveloped virus with a single-stranded positive-sense RNA. In 1978, BoAstV was first found in calf diarrhea fecal samples in the United Kingdom and since then it has been reported in many other countries. It has wide tissue tropism and can infect multiple organs, including the intestine, nerves and respiratory tract. Since BoAstV is prevalent in healthy as well as clinically infected bovines, and is mostly associated with co-infection with other viruses, the pathogenic nature of BoAstV is still unclear. At present, there are no stable passage cell lines available for the study of BoAstV and animal model experiments have not been described. In addition, it has been reported that BoAstV may have the possibility of cross-species transmission. This review summarizes the current state of knowledge about BoAstV, including the epidemiology, evolution analysis, detection methods, pathogenesis and potential cross species transmission, to provide reference for further research of BoAstV.

Prevalence and genetic characterization of bovine coronavirus identified from diarrheic pre-weaned native Korean calves from 2019 to 2021

Bovine coronavirus (BCoV) is associated with severe diarrhea in calves, winter dysentery in adult cattle, and respiratory diseases in cattle. However, there is currently limited information regarding its molecular characterization in the Republic of Korea (KOR). Therefore, this study investigated the prevalence of BCoV in diarrheic pre-weaned calves (aged ≤60 days) and compared BCoV genome sequences identified globally. A total of 846 fecal samples were collected from calves with diarrhea across 100 beef farms in the KOR. The samples were divided into three groups based on age as follows: 1-10 days (n = 490), 11-30 days (n = 277), and 31-60 days (n = 79). BCoV infection was detected in 50 calves by real-time RT-PCR analysis. The results showed that the prevalence of BCoV was associated with calf age (P = 0.028) and was significantly higher in calves aged 31-60 days (odds ratio: 2.69, 95% confidence interval: 1.24-5.85; P = 0.012) than in those aged 1-10 days. Our findings show that BCoV is an important etiological agent of diarrhea in calves aged 31-60 days. Fifteen full genome sequences (2019-2021 variants) of the spike, hemagglutinin/esterase, and nucleocapsid were obtained from the 50 BCoV-positive samples. Phylogenetic analysis of each gene revealed that BCoVs circulating worldwide might have no boundary between enteric and respiratory tropisms, demonstrating the presence of three BCoVs groups: the classical, Asia/USA, and European. Initially, Korean BCoVs were originated from the USA, but diverged since the 1980s and rapidly evolved independently, unlike in other Asian countries. In this study, Korean BCoVs are more recent BCoVs and present relatively high nucleotide substitution rates in all genes compared with other BCoVs. Our results showed that the 2019-2021 variants undergo continuous genetic evolution and that there are genetic differences among globally distributed BCoVs.

Diarrhoea outbreak caused by coinfections of Cryptosporidium parvum subtype IIdA20G1 and rotavirus in pre-weaned dairy calves

Diarrhoea is one of the most important syndromes in neonatal calves. In industrialized nations with intensive animal farming, Cryptosporidium spp. and rotavirus are primary causes of calf diarrhoea, but the role of these and other enteric pathogens is not clear in China. In November and December 2018, a diarrhoea outbreak was identified in over 150 pre-weaned calves on a dairy farm in Heilongjiang Province, northeast China and approximately 60 calves died. To determine the cause of the outbreak, we analyzed 131 faecal samples collected from pre-weaned calves (0-2 months) during (n = 114) and after the outbreak (n = 17). Initially, 10 diarrheic samples during the outbreak and 10 non-diarrheic samples after the outbreak were screened for rotavirus, coronavirus, Escherichia coli K99 and Cryptosporidium parvum by using an enzymatic immunoassay (EIA). In addition, 81 other samples were tested specifically for rotavirus by EIA, and all 131 samples were analyzed for Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi by PCR. The initial EIA analysis identified C. parvum (8/10) and rotavirus (5/10) as the dominant pathogens in calves during the outbreak, while both pathogens were detected at lower frequency after the outbreak (2/10 and 1/10, respectively). Further PCR analyses indicated that the occurrence of C. parvum infections in calves was significantly higher during the outbreak (75.4%, 86/114) than after the outbreak (11.8%, 2/17; odds ratio [OR] = 23.0), and was significantly associated with the occurrence of watery diarrhoea (OR = 15.7) and high oocyst shedding intensity. All C. parvum isolates were identified as subtype IIdA20G1. Among other pathogens analyzed, the overall prevalence of rotavirus, G. duodenalis and E. bieneusi was 19.8% (20/101), 38.9% (51/131) and 42.0% (55/131) in calves, respectively, without significant differences during and after the outbreak. Among the three pathogens, only the rotavirus infection was associated with diarrhoea in calves. More importantly, coinfections of C. parvum and rotavirus were significantly associated with the occurrence of watery diarrhoea in calves and were seen only during the outbreak. Thus, C. parvum subtype IIdA20G1 and rotavirus appeared to be responsible for this diarrhoea outbreak. Control measures should be implemented to effectively prevent the concurrent transmission of these enteric pathogens in pre-weaned dairy calves in China.

Indicators of the Condition of Newborn Calves after Difficult Labor Syndrome

Difficult Labor Syndrome is recorded in 37.9 % of newborn calves. Newborn calves assessed on the Apgar scale of 2 points, are assigned to the cluster class born after easy labor, 1 point – after moderate labor and 0 points for difficult labor. The characteristic features of newborn calves after light birth are the manifestation of statistical functions and free movement. In newborn calves born with moderate and severe labor severity, weakly expressed motor-food reflexes are manifested. Visible mucous membranes are pale in color. Breathing is slow and shallow. Heart sounds are weak, the pulse is arrhythmic, slowed down with a decrease in the pulse wave. Decrease in glucose concentration, increase in total bilirubin level by 1.9 times with moderate severity of labor and 2.5 times with severe course of labor. An excess of creatinine contributes to the liborilization of the function of eosinophils, as a result, a symptom develops due to sensitization of the body. The activity of gamma-lutamyl transpeptidase in newborn calves after the Difficult Labor Syndrome in one hour increases 18.6 times, the activity of alkaline phosphatase during this period increases 1.5 times, aspartate aminotransferase and alanine aminotransferase - 1.6 times, lactate dehydrotransferase - 1.3 times. The most significant increase in the first 24 hours is the activity of γ-glutamyl transferase. At the age of one day, it exceeds the initial one by 95.6 times. The studies carried out indicate that the concentration of double bonds in the blood of newborn calves after the Difficult Labor Syndrome is marked by an increase of 20.46 % with an average severity of labor and 34.13 % with a severe course of labor when compared with a mild severity of labor. The level of diene conjugates in the blood of newborn calves with mild labor severity in comparison with moderate labor severity was statistically significantly increased (p <0.05), and 1.87 times with severe labor (p <0.01). The concentration of intermediate products of ketodienes and conjugated trienes in the blood of newborn calves with mild labor severity was statistically significantly increased by 1.75 times compared with moderate labor severity and 3.54 times with severe labor (p <0.01). Reduced glutathione is among the considered indicators of the least sensitivity (26.0 %) and specificity (43.0 %) in newborn calves after the Difficult Labor Syndrome.

The Gut Microbiota of Newborn Calves and Influence of Potential Probiotics on Reducing Diarrheic Disease by Inhibition of Pathogen Colonization

Calf diarrhea is one of the most concerning challenges facing both the dairy and beef cattle industry. Maintaining healthy gut microbiota is essential for preventing gastrointestinal disorders. Here, we observed significantly less bacterial richness in the abnormal feces with watery or hemorrhagic morphology compared to the normal solid feces. The normal solid feces showed high relative abundances of Osllospiraceae, Christensenellaceae, Barnesiella, and Lactobacillus, while the abnormal feces contained more bacterial taxa of Negativicutes, Tyzzerella, Parasutterella, Veillonella, Fusobacterium, and Campylobacter. Healthy calves had extensive bacterial-bacterial correlations, with negative correlation between Lactobacillus and potential diarrheagenic Escherichia coli-Shigella, but not in the abnormal feces. We isolated Lactobacillus species (L. reuteri, L. johnsonii, L. amylovorus, and L. animalis), with L. reuteri being the most abundant, from the healthy gut microbiota. Isolated Lactobacillus strains inhibited pathogenic strains including E. coli K88 and Salmonella Typhimurium. These findings indicate the importance of a diverse gut microbiota in newborn calf’s health and provide multiple potential probiotics that suppress pathogen colonization in the gastrointestinal tract to prevent calf diarrhea.

Probiotic Lactobacilli Administration Induces Changes in the Fecal Microbiota of Preweaned Dairy Calves

Early microbial colonization is a determinant factor in animal health, and probiotic administration has been demonstrated to modulate intestinal microbiota and promote health in dairy calves. The objective of this study was to evaluate changes in calves' fecal microbiota after the administration of two probiotic lactobacilli strains that had previously exhibited beneficial effects in calves' health in relation to neonatal calf diarrhea. An in vivo assay was performed with 30 newborn male Holstein calves that were divided into three groups. Two groups were orally administered with two different lactobacilli strains (Lactobacillus johnsonii TP1.6 or Limosilactobacillus reuteri TP1.3B), and the third was the control group. Calves (5 to 9 days old) were administered with freeze-dried bacteria once a day for 10 consecutive days. Feces samples were taken before the first administration (day 0) and then again on days 10 and 21, and the V4 region of the bacterial 16S ribosomal gene was sequenced with an Illumina MiSeq 250 paired-end platform. The administration of both strains significantly affected the total bacterial community composition, and the effect lasted for 11 days after the last dose. In particular, amplicon sequence variants related to Bifidobacterium and Akkermansia genera were significantly higher in both treated groups. Therefore, modulation of the intestinal microbiota is a potential mechanism of action behind the beneficial effects of these probiotic strains.

The Antibiotic Treatment of Calf Diarrhea in Four European Countries: A Survey

Neonatal calves are commonly affected by diarrhea caused by different pathogens, but not always bacteria. Yet, antibiotics are routinely used as a treatment to an unknown extent. It was our goal to survey antibiotic use for the treatment of neonatal calf diarrhea in different countries and to identify influencing factors. A total of 873 farmers and veterinarians in Austria, Belgium, Portugal, and Scotland participated in a voluntary online survey. The data were analyzed using classification and regression tree analyses and chi² tests. Overall, 52.5% of the participants stated that they use antibiotics when treating neonatal calf diarrhea. Of those, 27% use them always, and 45% use highest priority critically important antibiotics. The most important factor differentiating antibiotic use practices was the country the participants were from, which could be due to regulatory differences between the countries. All antibiotic products stated were licensed for use in cattle, but several were not licensed for the treatment of diarrhea in calves. Our study shows that there is an urgent need for more scientific evidence to define best practices for the treatment of neonatal calf diarrhea. Furthermore, consensual criteria for antibiotic therapy must be defined, and targeted training for farmers and veterinarians must be provided.

Beyond the Gastrointestinal Tract: The Emerging and Diverse Tissue Tropisms of Astroviruses

Astroviruses are single stranded, positive-sense RNA viruses that have been historically associated with diseases of the gastrointestinal tract of vertebrates, including humans. However, there is now a multitude of evidence demonstrating the capacity of these viruses to cause extraintestinal diseases. The most striking causal relationship is neurological diseases in humans, cattle, pigs, and other mammals, caused by astrovirus infection. Astroviruses have also been associated with disseminated infections, localized disease of the liver or kidneys, and there is increasing evidence suggesting a potential tropism to the respiratory tract. This review will discuss the current understanding of the tissue tropisms for astroviruses and their emerging capacity to cause disease in multiple organ systems.

Occurrence of Cryptosporidium and other enteropathogens and their association with diarrhea in dairy calves of Buenos Aires province, Argentina

Cryptosporidiosis of neonatal dairy calves causes diarrhea, resulting in important economic losses. In Argentina, prevalence values of Cryptosporidium spp. and other enteropathogens such as group A rotavirus (RVA), bovine coronavirus (BCoV) and enterotoxigenic Escherichia coli (ETEC, endotoxin STa⁺), have been independently studied in different regions. However, an integrative epidemiological investigation on large-scale farms has not been carried out. In this study, fecal samples (n = 908) were randomly collected from diarrheic and healthy calves from 42 dairy farms, and analyzed for the presence of Cryptosporidium spp., RVA, BCoV, ETEC (STa⁺) and Salmonella spp. In all sampled dairy farms, dams had been vaccinated against rotavirus and gram-negative bacteria to protect calves against neonatal diarrhea. The proportion of calves shedding Cryptosporidium spp., RVA, and BCoV in animals younger than 20 days of age were 29.8%, 12.4% and 6.4%, and in calves aged between 21 and 90 days, 5.6%, 3.9%, and 1.8%, respectively. ETEC was absent in the younger, and occurred only sporadically in the older group (0.9%), whereas Salmonella spp. was absent in both. The observed sporadic finding or even absence of bacterial pathogens might be explained by the frequent use of parenteral antibiotics in 25.3% and 6.5% of the younger and the older group of calves, respectively, within 2 days prior to sampling and/or vaccination of dams against gram-negative bacteria. Diarrhea was observed in 28.8% (95% CI, 24.7-32.8%) of the younger calves and 11.7% (95% CI, 9.1-15.5%) of the older calves. Importantly, Cryptosporidium spp. (odds ratio (OR) = 5.7; 95% CI, 3.3-9.9; p < 0.0001) and RVA (OR = 2.5; 95% CI, 1.2-5.1; p < 0.05) were both found to be risk factors for diarrhea in calves younger than 20 days old. Based on its high prevalence and OR, our results strongly suggest that Cryptosporidium spp. is the principal causative factor for diarrhea in the group of neonatal calves, whereas RVA seems to play a secondary role in the etiology of diarrhea in the studied farms, with about three-times lower prevalence and a half as high OR. Furthermore, a coinfection rate of Cryptosporidium spp. and RVA of 3.7% was observed in the group of younger calves, which strengthens the assumption that these events are independent. In contrast, due to a low infection rate of enteropathogens in older calves, mixed infection (<< 1%) was virtually absent in this group.