Pathogens In Calves Research Articles

Association between lung consolidation and serum amyloid-A and haptoglobin, and the potential of acute phase proteins to differentiate primary respiratory tract pathogens in calves

Bovine respiratory disease (BRD) remains a leading cause of economic losses, hampered animal welfare and antimicrobial use. The use of acute phase proteins (APPs), such as serum amyloid A (SAA) and haptoglobin (Hp), has been explored for the detection of BRD, as defined by clinical signs. However, whether these APPs are also associated with lung consolidation, as determined by thoracic ultrasonography, and have the potential to differentiate causative pathogens is unknown. Therefore, the primary objective of this study was to explore the association between lung consolidation and SAA and Hp. The second objective was to determine the ability of both SAA and Hp to differentiate pathogen groups (Mycoplasmopsis bovis, viruses and Pasteurellaceae). A cross-sectional study including 170 calves from 25 different herds with a history of Mycoplasmopsis bovis (M. bovis) (endemic, n = 94, 9 herds) or herds (including M. bovis positive herds) that met the inclusion criteria of an outbreak of BRD (i.e., the presence of one or more clinical signs associated with BRD, affecting multiple animals (5 animals; 15% ill animals in the same airspace on a farm within a 48-h period) (epidemic, n = 76, 16 herds) was conducted between 2020 and 2022 in Belgium. Clinical examination, quick thoracic ultrasonography (qTUS), blood sampling and non-endoscopic bronchoalveolar lavage (nBAL) were performed on each calf. Linear mixed effect models with a random intercept for herd were fitted, to determine the association between lung consolidations (depth ≥ 1 cm or ≥3cm) or clinical BRD (UC Davis BRD scorecard positive) and serum SAA and Hp concentrations. Furthermore, multivariable models (linear mixed effect models) were used to evaluate the mutually adjusted associations between pathogen groups and APP concentrations. Test characteristics of APP concentrations to predict the presence of lung consolidation or pathogen groups were assessed, and potential SAA and Hp cutoffs, determined by Youden index, were evaluated. Lung consolidation (≥1 cm) was positively association with higher Hp concentrations in epidemic conditions [regression coefficient (β): 5.3 (95% confidence interval (CI): 1.4-20.3)], while more severe lung consolidation (≥3 cm) was associated with higher Hp concentrations in endemic conditions [β: 3.6 (95% CI: 1.2-11.0)]. No positive association was found between lung consolidation and SAA. Yet, a positive association between M. bovis and SAA was observed [β: 2.3 (95% CI: 1.3-4.3)]. At last, no association was found between M. Bovis and Hp. For Hp, the best cutoff to predict a lung consolidation (≥1 cm) was 2.33 µg/mL (Se: 81.8% and Sp: 66.7%). Moreover, to detect M. bovis among calves with a lung consolidation (≥1 cm), a SAA cutoff of 174.84 µg/mL was determined (Se: 77.8% and Sp: 87.5%). Despite the observed relationships between lung consolidation, pathogen groups, and APPs, the test characteristics in this study suggest that Hp and SAA are currently limited in their (practical) use for the detection of lung consolidation or M. bovis.

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

BackgroundCalf 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.ResultsAll 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.ConclusionsOur 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.

Experimental immunotherapy of association infections of the gastrointestinal tract of newborn calves using yolk melange enriched with specific Y class immunoglobulins

Mass gastrointestinal diseases of newborn calves manifested by symptoms of diarrhea are caused by various etiological factors and most often occur in the form of mixed infections. Mixed infections have a more severe diarrhea than mono-infections. The economic consequences of such infections due to the high prevalence, frequent mortality and loss of productivity during further exploitation of the animal can be significant. The most common causative agents of gastrointestinal diseases of newborn calves of viral etiology is rotavirus and coronavirus infections. Mixed (viral-bacterial) infection can lead to 100% mortality of the diseased calves. Specific vaccination of springer cows against gastrointestinal pathogens in calves, which is performed to increase the number of pathogen-specific immunoglobulins in the colostrum at calf birth, and ingestion of colostrum by the calves during the first 4 hours of life are the most important strategies to prevent severe diarrhea. But as practice shows, this is not always enough. The purpose of this work was to study the effectiveness of immunoprophylaxis of associative infections of the gastrointestinal tract of newborn calves with the use of melange prepared from chicken eggs previously immunized with the vaccine "Rotagal" (Pharmagal-BIO s.r.o., Slovakia), used for the prevention of colibacillosis, rotavirus and coronavirus infections of cattle. As a result of the study, it was established that the addition of yolk melange rich in specific immunoglobulins of Y class to the colostrum in the first hours of life of the calves has a pronounced prophylactic effect, facilitates the course of the infectious process in case of the disease, saves costs for the treatment of sick animals, increases survival rate, contributes to the acceleration of live weight gain. The use of an immunobiological preparation based on transovarial immunoglobulins has a positive effect on the indicators of nonspecific resistance of newborn calves compared to the calves with early postnatal disease and antibiotic treatment.

Association between respiratory disease pathogens in calves near feedlot arrival with treatment for bovine respiratory disease and subsequent antimicrobial resistance status.

This study assessed the risk of first treatment for bovine respiratory disease (BRD) given detection of nasopharyngeal bacteria (Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni) and corresponding likelihood of antimicrobial susceptibility (C/S) at two time points during the early feeding period. Relationships between C/S results and later treatment for BRD were evaluated at both the calf-level and pen-level. The association between calf-level and pen-level C/S findings during the early feeding period and subsequent C/S results at BRD treatment were also reported. Auction-sourced, recently-weaned beef calves (n = 1,599 steers) were placed in adjacent feedlot pens (8 × 100 calves) in two subsequent years. Deep nasopharyngeal (DNP) swabs were collected from all calves at time of arrival processing (1DOF) and before metaphylaxis administration with either tulathromycin or oxytetracycline, 12 days later (13DOF), and at the time of first treatment for BRD. All samples were tested for C/S. Several pen-level and individual calf-level C/S measures of interest were associated with future treatment for BRD and C/S at the time of treatment. The median DOF for first BRD treatment was 24 days following tulathromycin metaphylaxis and 11 days following oxytetracycline. Overall, sampling at 13DOF resulted in the best fit for more models of subsequent treatment for BRD and C/S results at BRD treatment than for sampling at arrival. In individual calves, recovery of M. haemolytica, P. multocida, or H. somni at 13DOF was associated with subsequent treatment for BRD within 45DOF. Pen-level prevalence of Pasteurellacea bacteria with tetracycline or macrolide resistance at arrival and 13DOF were associated with detection of bacteria with antimicrobial resistance (AMR) at BRD treatment, as were individual calf results at 13DOF. These findings suggest that the bacteria and AMR outcomes recovered from cattle near two weeks on feed can inform the prediction of future BRD risk and concurrent antimicrobial susceptibility results at time of first BRD treatment. Notably, the associations between pen-level C/S results from previous testing and corresponding findings in calves with BRD from the same pen suggested potential testing strategies to inform antimicrobial use protocols for feedlot cattle.

Comparing Occurrence of Bovine Respiratory Pathogens Detected by High-Throughput Real-Time PCR in Nasal Swabs and Non-Endoscopic Bronchoalveolar Lavage Samples from Dairy and Veal Calves.

This study aimed to enhance our understanding of the agreement between two sampling methods for the detection of bovine respiratory disease (BRD) pathogens in calves using high-throughput real-time qPCR (ht-RT-qPCR). In total, 233 paired nasal swab (NS) and non-endoscopic bronchoalveolar lavage (nBAL) samples were collected from 152 calves from 12 Danish cattle herds. In 202 of the observations, the calves were examined using a standardized clinical protocol. Samples were tested for three viruses (bovine respiratory syncytial virus, bovine corona virus, and influenza D virus) and six bacteria (Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, Mycoplasma species, Pasteurella multocida, and Truepurella pyogenes). The results showed age-related differences in disease and pathogen occurrence, with the highest detection rates in calves aged 35 days or older. Poor to moderate agreement was found between the NS and nBAL results. The presence of Mannheimia haemolytica in both NS and nBAL in younger calves and in nBAL in older calves was associated with clinical BRD. There was a potential link between BRD and influenza D virus in older calves, although it was only found in one herd in a small sample size. Overall, NS was a relatively poor predictor of pathogens in the lower respiratory tract. The present study confirms the complexity of pathogen detection in BRD, with marked influences of age and the sampling method on pathogen detection and disease associations.

Diarrheagenic pathogens in calves with diarrhea in Chungcheongbuk-do, Korea, from 2018 to 2021

Diarrheagenic pathogens in calves with diarrhea in Chungcheongbuk-do, Korea, from 2018 to 2021

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.

Occurrence of major and minor pathogens in calves diagnosed with bovine respiratory disease

Bovine respiratory disease (BRD) is caused by a mixture of viruses and opportunistic bacteria belonging to Pasteurellaceae and Mycoplasma bovis. However, these organisms are also commonly isolated from healthy calves. This study aimed to determine whether the organisms are present in higher numbers in calves sick with acute BRD than in clinically healthy calves, and further to genetically characterize bacteria of the family Pasteurellaceae to understand whether particular types are associated with disease. Forty-six clinically healthy and 46 calves with BRD were sampled by broncheoalveolar lavage (BAL) method in 11 herds geographically spread over Denmark to determine presence and quantity of microorganisms by culture and quantitative real time qPCR. Isolates of Pasteurellaceae were tested for antibiotic resistance and were whole genome sequenced to determine genotypes. Histophilus somni was in particular positively associated with BRD, suggesting particular importance of this organism as likely aetiology of BRD. In addition, quantification of bacteria revealed that higher counts of H. somni as well as of M. haemolytica was also a good indicator of the disease. Pasteurellaceae isolates were susceptible to the commonly used antibiotics in treatment of BRD, and genotypes were shared between isolates from clinically healthy and sick calves.

Prevalence and Antimicrobial Resistance of Escherichia coli, Enterococcus spp. and the Major Foodborne Pathogens in Calves in Latvia.

The aim of the present study was to detect the prevalence and antimicrobial resistance of fecal indicators and major foodborne pathogens in feces of calves and to identify the factors associated with increased prevalence of resistant bacteria on farms. Altogether, 180 rectal swabs were collected from 18 farms in Latvia. Samples were investigated to detect the prevalence and antimicrobial resistance of Escherichia coli, Enterococcus spp., Listeria monocytogenes, Yersinia enterocolitica, Salmonella spp., Staphylococcus aureus, and Campylobacter spp. Among all, 64% (74/110) of commensal E. coli, 100% (78/78) Enterococcus faecalis and 96% (22/23) Enterococcus faecium isolates were resistant at least to one antibiotic. The prevalence of extended-spectrum β-lactamase (ESBL)/AmpC-producing E. coli were 11.1% (20/180) with blaCTX-M, blaTEM, and blaCMY genes identified. Campylobacter jejuni (12.8%, 23/180) and Campylobacter coli (2.8%, 5/180) were the most resistant to tetracycline (61%, 14/23; 100%, 5/5) and fluoroquinolones (61%, 14/23; 100%, 5/5). Prevalence of L. monocytogenes was 0.6% (1/180) and S. aureus 1.7% (3/180). All samples were Salmonella and Y. enterocolitica negative. Farm size, bought calves, contact with other calves, and antimicrobial treatment of cows were associated with increased prevalence of resistant E. coli and Enterococcus spp. Despite the low overall usage of antimicrobials in Latvia, the high rates of antimicrobial resistance in fecal indicators and Campylobacter, in addition to the high prevalence of ESBL-producing E. coli, highlights the necessity for the prudent use of antimicrobials in dairy farms in Latvia.

Genome-wide pleiotropy and shared biological pathways for resistance to bovine pathogens

Host genetic architecture is a major factor in resistance to pathogens and parasites. The collection and analysis of sufficient data on both disease resistance and host genetics has, however, been a major obstacle to dissection the genetics of resistance to single or multiple pathogens. A severe challenge in the estimation of heritabilities and genetic correlations from pedigree-based studies has been the confounding effects of the common environment shared among relatives which are difficult to model in pedigree analyses, especially for health traits with low incidence rates. To circumvent this problem we used genome-wide single-nucleotide polymorphism data and implemented the Genomic-Restricted Maximum Likelihood (G-REML) method to estimate the heritabilities and genetic correlations for resistance to 23 different infectious pathogens in calves and cows in populations undergoing natural pathogen challenge. Furthermore, we conducted gene-based analysis and generalized gene-set analysis to understand the biological background of resistance to infectious diseases. The results showed relatively higher heritabilities of resistance in calves than in cows and significant pleiotropy (both positive and negative) among some calf and cow resistance traits. We also found significant pleiotropy between resistance and performance in both calves and cows. Finally, we confirmed the role of the B-lymphocyte pathway as one of the most important biological pathways associated with resistance to all pathogens. These results both illustrate the potential power of these approaches to illuminate the genetics of pathogen resistance in cattle and provide foundational information for future genomic selection aimed at improving the overall production fitness of cattle.

Mycoplasma infections in calves

Mycoplasma bovis is an important pathogen of calves causing respiratory disease, otitis and arthritis. Management of outbreaks can be difficult due to the variable response to treatment and rapid spread between in-contact animals, so it is vital that the disease is rapidly identified and the appropriate control measures are implemented.

Multilocus genotyping of Giardia duodenalis and Enterocytozoon bieneusi in dairy and native beef (Qinchuan) calves in Shaanxi province, northwestern China.

Giardia duodenalis and Enterocytozoon bieneusi are two common protozoa that parasitize the intestinal epithelium of animals and humans. Calves have been identified as important reservoirs of these two pathogens, but limited data is available for these two pathogens in calves in China. In the present study, the prevalence and assemblages/genotypes of both parasites in calves of dairy and native beef (Qinchuan) cattle in Shaanxi province, northwestern China, were analyzed using multilocus genotyping (MLST). Of 371 fecal samples collected from calves (including 198 dairy calves and 173 Qinchuan calves), the respective overall prevalence of G. duodenalis and E. bieneusi was 18.87 (70 of 371) and 19.68 % (73 of 371). Both the zoonotic G. duodenalis assemblage A and animal adapted assemblage E were found in dairy and Qinchuan calves. Seventeen, eight, five, and two G. duodenalis subtypes were detected at the triose phosphate isomerase (tpi), β-giardin (bg), glutamate dehydrogenase (gdh), and small subunit ribosomal RNA (SSU-rRNA) loci, with five and two novel subtypes detected at the tpi and bg loci, forming 25 multiple genotypes (MLGs) (15 and 11 in dairy and Qinchuan calves, respectively). Of 73 samples that were positive for E. bieneusi at the ribosomal RNA internal transcribed spacer (ITS) locus, five ITS genotypes were found, including three known zoonotic genotypes (I, J, CHN1) and two novel genotypes (CSX1 and CSX2). MLST analysis of three microsatellite loci (MS1, MS3, MS7) and one minisatellite locus (MS4) detected six, two, two, and two genotypes at the MS1, MS3, MS4, and MS7 loci, respectively, forming ten MLGs (seven and four in dairy and Qinchuan calves, respectively). These results indicate complex population structures of G. duodenalis and E. bieneusi in calves in Shaanxi province and the zoonotic potential of these two pathogens in calves in this province.

Prevalence and Risk Factor Identification of Calf Coccidiosis in and Around Bahir Dar Town in Amhara Regional State, North West Ethiopia

A cross sectional study was conducted from November 2014 to April 2015 in and around Bahir Dar town to determine the prevalence of Coccidia infection in calves and to identify associated risk factors. Fecal samples were collected from a total of 384 randomly selected calves with the age of under 2 years. Collected fecal samples were examined for the presence of Eimeria oocyst by flotation technique. Out of 384 calves, 73 (19.01%) were found to be positive for Eimeria oocyst. Analysis of potential risk factors has revealed that; there was statistically significant difference (P 0.05) between coccidia infection with sex and breed of calves. In conclusion, the present finding has demonstrated that calf coccidia are one of the most important pathogens in calves in the study area. Therefore, further epidemiological investigations are required to determine the Eimeria species composition and different agro ecological risk factor on the occurrence of the disease.

Comparing the immune response to a novel intranasal nanoparticle PLGA vaccine and a commercial BPI3V vaccine in dairy calves.

BackgroundThere is a need to improve vaccination against respiratory pathogens in calves by stimulation of local immunity at the site of pathogen entry at an early stage in life. Ideally such a vaccine preparation would not be inhibited by the maternally derived antibodies. Additionally, localized immune response at the site of infection is also crucial to control infection at the site of entry of virus. The present study investigated the response to an intranasal bovine parainfluenza 3 virus (BPI3V) antigen preparation encapsulated in PLGA (poly dl-lactic-co-glycolide) nanoparticles in the presence of pre-existing anti-BPI3V antibodies in young calves and comparing it to a commercially available BPI3V respiratory vaccine.ResultsThere was a significant (P < 0.05) increase in BPI3V-specific IgA in the nasal mucus of the BPI3V nanoparticle vaccine group alone. Following administration of the nanoparticle vaccine an early immune response was induced that continued to grow until the end of study and was not observed in the other treatment groups. Virus specific serum IgG response to both the nanoparticle vaccine and commercial live attenuated vaccine showed a significant (P < 0.05) rise over the period of study. However, the cell mediated immune response observed didn’t show any significant rise in any of the treatment groups.ConclusionCalves administered the intranasal nanoparticle vaccine induced significantly greater mucosal IgA responses, compared to the other treatment groups. This suggests an enhanced, sustained mucosal-based immunological response to the BPI3V nanoparticle vaccine in the face of pre-existing antibodies to BPI3V, which are encouraging and potentially useful characteristics of a candidate vaccine. However, ability of nanoparticle vaccine in eliciting cell mediated immune response needs further investigation. More sustained local mucosal immunity induced by nanoparticle vaccine has obvious potential if it translates into enhanced protective immunity in the face of virus outbreak.

Molecular characterization of Cryptosporidium parvum from two different Japanese prefectures, Okinawa and Hokkaido

Infectious diarrhea is the most frequent cause of morbidity and mortality in neonatal calves. Cryptosporidium parvum is one of the main pathogens associated with calf diarrhea. Although diarrhea is a symptom of infection with various pathogens, investigations to detect the types of pathogens have never been performed in Japan. This study investigated the prevalence of four major diarrhea-causing pathogens in calves: C. parvum, rotavirus, coronavirus, and enterotoxigenic Escherichia coli (E. coli K99). Commercial immunochromatography testing of all four pathogens and molecular analysis of C. parvum with diarrhea in calves from southernmost Okinawa and northernmost Hokkaido, Japan, were conducted. The frequencies of C. parvum, rotavirus, coronavirus, and E. coli (K99) in Okinawa were 50%, 28%, 2.3%, and 4.7%, respectively. Watery fecal stools were significantly correlated with C. parvum (p<0.05). In oocyst calculations for C. parvum, no significant difference was observed between the single-infection cases and the mixed-infection cases with rotavirus. Interestingly, molecular analyses targeting small subunit ribosomal RNA as well as glycoprotein 60 (GP60) genes revealed that the C. parvum nucleotide sequences from the two prefectures were identical, indicating that C. parvum with a uniform characteristic is distributed throughout Japan. GP60 subtyping analysis identified C. parvum from Okinawa and Hokkaido as belonging to the IIaA15G2R1 subtype, a known zoonotic subtype. Hence, control of cryptosporidiosis is important not only for pre-weaned calves, but also for human health.

The effect of Fasciola hepatica infection on respiratory vaccine responsiveness in calves

Fasciola hepatica is a common parasite in cattle, and bovine fasciolosis causes significant production losses, as well as being a zoonotic disease of global importance. F. hepatica has been shown to have immunoregulatory effects and the aim of this research was to establish whether F. hepatica infection influences the response to vaccination against respiratory pathogens in calves. A total of 48 calves were randomly and equally allocated to two groups. The experimental group was infected with F. hepatica, while the other group was used as a control. At week 2 and 6 after infection calves from both groups were administered a vaccine containing inactivated PI-3, BRSV and Mannheimia haemolytica, pathogens commonly associated with bovine respiratory disease. Blood samples were taken weekly over 12 weeks to measure specific antibodies against all vaccine antigens and against F. hepatica, as well as IgG1 and IgG2 isotypes for PI-3 and BRSV specific antibodies. Faecal samples were examined for F. hepatica eggs and routine haematology and liver enzyme biochemistry were performed and cytokine production in vitro measured. Liver enzymes (GGT and GLDH) and eosinophils were significantly higher in the experimental group, whereas neutrophil numbers were higher in the control group. There was no significant difference between the groups in terms of vaccine-specific total responses to PI-3, BRSV and M. haemolytica. IgG1 levels were higher in comparison to IgG2 levels in both PI-3 and BRSV specific antibodies. IL-4 levels from stimulated and unstimulated PBMC were significantly higher in the control group. IFN-γ levels were significantly higher in PBMC from the control group when cultured in medium only. No significant differences were noted in the levels of other cytokines measured. In this work, no effect of early F. hepatica infection on the antibody responses to a range of respiratory vaccine antigens in calves was shown. However, differences in cytokine responsiveness of PBMC between control and infected groups were observed, indicating that further work in measuring the effect of F. hepatica infection response to challenge infection following vaccination would be warranted.

Prevalence of bovine coccidia in Kombolcha district of South Wollo, Ethiopia

A cross sectional study was conducted from November 2011 up to April 2012 in Kombolcha town to determine the prevalence of coccidia infection in calves. Fecal samples were collected from a total of 288 calves with the age of 1 month to 1 year old which were included in the study purposively. After collection, the samples were transported to the laboratory and examined for the presence of Eimeria oocyst by flotation techniques. For positive sample, a solution of 2.5% potassium dichromate (K2Cr2O7) was added to the feces containing the oocyst for sporulation and identification of the species. Out of 288 calves, 92 (31.9%) were found to be positive forEimeria species. There was statistically significant difference (P 0.05) between coccidia infection and sex, breed, body condition, address or management system. Five species of Eimeria were identified in the study and the most prevalent species wereEimeria bovis (42.3%), Eimeria zuernii (28.3%) and Eimeria auburnensis (13.0%). The other species were E. ellipsoidalis (8.7%), E. alabamensis (4.3%) and unidentified oocyst (3.3%). In conclusion, the present finding has demonstrated that bovine coccidia are one of the important pathogens in calves in the study area. Further epidemiological investigations are required to determine the Eimeria species composition and different agro ecological risk factor on the occurrence of the disease. Key words: Calves, coccidiosis, Eimeria, Kombolcha, prevalence, risk factors.

Influence of tilmicosin on quantified pulmonary concentrations of three bacterial pathogens in calves with naturally-occurring bovine respiratory disease

A randomized trial was conducted to determine the lower respiratory tract pathogen load in cattle at risk of developing bovine respiratory disease (BRD). The objectives were to characterize and quantify concentrations of respiratory pathogens in the main-stem bronchi before and after administration of tilmicosin as a treatment for BRD.Ninety-three beef steers and heifers were selected from a group of 421 high-risk calves based on a BRD case definition that included clinical score and rectal temperature parameters. Three calves meeting the BRD case definition constituted a cohort; 1 animal within a cohort served as an untreated control, whereas the remaining 2 received 6.75 mg/lb (14.85 mg/kg) of body weight tilmicosin. An aliquot of solution obtained via lavage of the main-stem bronchi upon enrollment and at 72, 144, and 216 hours post-enrollment was serially diluted and cultured for respiratory bacteria.Treated animals had significant reductions (P&lt;0.05) in Mannheimia haemolytica concentrations at each post-enrollment time point compared to untreated controls, while concentrations of Histophilus somni at 144 and 216 hours post-enrollment were lower than untreated controls. Rectal temperature was also reduced (P&lt;0.05) at all post-enrollment sampling times in calves treated with tilmicosin. An improvement (P&lt;0.05) in clinical score during the post-enrollment period was noted for calves receiving tilmicosin.

Apparent Prevalence of Congenital Infections in Calves Born on a Single California Dairy Herd

The placenta in cattle prevents in utero transfer of maternal immunoglobulins and leukocytes to the fetus. The fetal immune system, on the other hand, can be exposed to pathogens that cross the placental barrier and mount an immune response to bovine leukosis virus (BLV), infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD) types 1 and 2, Neospora caninum (NC), Leptospira hardjo (LH), and Leptospira Pomona (LP). The objective of this study was to determine the apparent prevalence of congenital infections to common infectious pathogens in calves.

Field efficacy of combination vaccines against bovine respiratory pathogens in calves

The efficacy of an inactivated bovine respiratory syncytial virus (BRSV)--bovine parainfluenza type 3 (PI3)--Mannheimia haemolytica (Mh) combination vaccine was examined in two field studies. Calves were vaccinated (i) with the inactivated vaccine, (ii) a modified live/killed viral combination vaccine, or (iii) left unvaccinated. The efficacy of the vaccines was judged by the (i) number of treated animals, (ii) number of individual antibiotic treatments per calf and (iii) mortality rates. After vaccination with the inactivated vaccine, the number of calves requiring antibiotic treatment was significantly lower than in the unvaccinated group (odds ratios: 0.26 first study and 0.53 second study), but differences between vaccination with live/killed combination vaccines and controls were not significant (odds ratios: 0.56 and 0.90, respectively). In both studies, a number of unvaccinated controls died due to respiratory disease (4.6% first and 6.7% second study). By contrast, none of the animals vaccinated with the inactivated vaccine died in the first study and only 3.3% in the second study. The mortality rates for the groups vaccinated with the live vaccine (1.3% and 7.8%) were similar to the unvaccinated controls. In summary, these data demonstrate the efficacy of the inactivated vaccine under field conditions.