Chlamydial infection and on-farm risk factors in dairy cattle herds in South East Queensland

The effects of differential feeding on ileum development, digestive ability and health status of newborn calves

Pre-weaning is the most important period for the growth and development of calves. Intestinal morphology, microbial community and immunity are initially constructed at this stage, and even have a lifelong impact on calves. Early feeding patterns have a significant impact on gastrointestinal development and microbial communities. This study mainly analyzed the effects of three feeding methods on the gastrointestinal development of calves, and provided a theoretical basis for further improving the feeding mode of calves. it is very important to develop a suitable feeding mode. In this study, we selected nine newborn healthy Holstein bull calves were randomly selected and divided into three groups (n = 3), which were fed with starter + hay + milk (SH group), starter + milk (SF group), total mixed ration + milk (TMR group). After 80 days of feeding Feeding to 80 days of age after, the ileum contents and blood samples were collected, and the differences were compared and analyzed by metagenomic analysis and serum metabolomics analysis. Results show that compared with the other two groups, the intestinal epithelium of the SH group was more complete and the goblet cells developed better. The feeding method of SH group was more conducive to the development of calves, with higher daily gain and no pathological inflammatory reaction. The intestinal microbial community was more conducive to digestion and absorption, and the immunity was stronger. These findings are helpful for us to explore better calf feeding patterns. In the next step, we will set up more biological replicates to study the deep-seated reasons for the differences in the development of pre-weaning calves. At the same time, the new discoveries of neuro microbiology broaden our horizons and are the focus of our future attention.

Prevalence of infectious diseases on dairy farms classified on the basis of their biosecurity score

Introduction

The aim of the study was to investigate the relationship between biosecurity as scored on the Italian National Animal Welfare Reference Centre (Centro di Referenza Nazionale per il Benessere Animale – CReNBA) checklist and the prevalence of Mycobacterium avium subsp. paratuberculosis, Chlamydophila abortus and Neospora caninum on dairy farms located in Ragusa, Italy.

Material and Methods

The checklist was used to assign an animal welfare score to 31 dairy farms. Twenty-one farms with a moderate score (>33%, <66%) formed group 1, and 10 farms with a high score (>66%) were group 2. Blood samples were collected from all cows on each farm to investigate the titres of antibodies against the relevant pathogens. Two-way analysis of variance was applied to assess differences between the two experimental groups and the Mann–Whitney test was applied to evaluate prevalence differences in the tested parasites between the groups.

Results

All tested farms had a score that classified them as either good or excellent. A higher incidence of Neospora caninum was observed in group 1. The incidences of the other two parasites were no different between the two groups.

Conclusion

The CReNBA checklist represents an impartial, reproducible, functional and smart instrument based on risk analysis and assigns a farm a mathematical animal welfare score. Among the parasites tested for, only Neospora caninum had prevalence influenced by biosecurity. Our preliminary results highlighted the positive associations between good animal welfare, high levels of biosecurity, and the prevention of the infectious diseases caused by the parasites in our focus, which are common on dairy farms.

A Meta-Analysis of Bovine Chlamydia Prevalence in Cattle in China from 1989 to 2020

Chlamydia bovis is a widespread infection disease caused by the mixed infection of Chlamydia psittaci, Chlamydia pecorum, Chlamydia abortus, and Chlamydia suis in cattle. Although many studies have investigated Chlamydia infection in cattle, there is no nationwide study on the prevalence of Chlamydia infection in cattle of China. We constructed the first meta-analysis to assess the infection rate and infection risk factors of Chlamydia in cattle in China, and we searched PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and VIP Chinese journal database for studies reporting Chlamydia infection in cattle from April 29, 2020. We collected a total of 563 publications from 1989 to 2019, and finally, 78 studies were eligible, which included 152,364 cattle from 27 provinces across the country. We estimated the pooled prevalence of Chlamydia in cattle was 14.2% (95% confidence interval [CI]: 12.2 to 16.4). The prevalence of bovine Chlamydia in China collected before 2000 (14.8%, 95% CI: 5.6 to 27.3) showed the highest prevalence rate. The highest prevalence was found in Central China (22.6%, 95% CI: 12.8 to 34.2). The prevalence of Chlamydia spp. between abortion cattle (39.1%, 95% CI: 24.6 to 54.6) and healthy cattle (8.3%, 95% CI: 3.1 to 15.2) showed significant variation (p < 0.05). In detection methods subgroup, enzyme-linked immunosorbent assay (30.5%, 95% CI: 21.5 to 40.3) showed the highest prevalence. In the age subgroup, the prevalence rate of age >1 year (16.6%, 95% CI: 12.6 to 20.9) was higher compared with age ≤1 year (9.8%, 95% CI: 6.7 to 13.3). Yaks (17.8%, 95% CI: 13.3 to 22.8) showed the highest Chlamydia prevalence among the varieties of bovine. We also estimated the potential risk factors such as feeding model, sample classification, sampling seasons, bovine gender, parity, and quality level of included studies. Our findings suggested that Chlamydia was prevalent in cattle in China. So we should pay attention to bovine Chlamydia and take necessary measures to prevent it.

Management Factors Influence Animal Welfare and the Correlation to Infectious Diseases in Dairy Cows

The present study assessed dairy cow welfare through the application of the Italian National Animal Welfare Reference Center (CReNBA) checklist in 36 dairy farms located in Ragusa (Italy) subjected to two different management conditions, housing with free access to pasture (Group 1, farms n = 17) and indoor housing (Group 2, farms n = 19). Five areas of investigation were considered: Area A, "Farm management and personnel"; Area B, "Facilities and equipment"; Area C, "Animal-based measures"; Area D, "Inspection of microclimatic environmental conditions and alarm systems"; and Area E, "Biosecurity". Blood samples were collected by coccygeal venipuncture from all animals (4081 cows). The specific antibodies against Mycobacterium avium subsp. paratuberculosis, Chlamydiophila abortus, Neospora caninum, bovine viral diarrhea virus, and the bovine herpesvirus were assessed by enzyme linked immunosorbent assay (ELISA) serological test. Group 1 (access to pasture) showed a lower value of percentage score recorded in Area A (p = 0.02) and E (p = 0.01) than Group 2 (indoor housing). Herpesvirus (Infectious bovine rhinotracheitis - IBR - detection of gB antibodies/IBR-gB) blood concentrations were higher in the cows housed indoor versus those with access to pasture (p = 0.01). Farm management and personnel (score A) was correlated with the level of bovine viral diarrhea virus (τ = 0.3754) and bovine-herpesvirus-specific antibodies (IBR-gB) (τ = 0.4159). "Biosecurity" percentage score showed a significant correlation with Chlamydiophila abortus (τ = -0.4621) in the cows with access to pasture and IBR-gB (τ = 0.3435) in the cows housed fully indoors. Group 2 showed a significantly reduced level of antibodies against Neospora caninum. In conclusion, differences in the welfare assessment score were observed in the "Farm management and personnel" and "Biosecurity" between the two management conditions. It had an effect on the prevalence of herpesvirus, which occurred more in cattle with access to pasture. Therefore, an accurate application of the checklist could be an instrument to prevent and control the spread of infections in farms.

Chlamydia Psittaci ST24: Clonal Strains of One Health Importance Dominate in Australian Horse, Bird and Human Infections

Chlamydia psittaci is traditionally regarded as a globally distributed avian pathogen that can cause zoonotic spill-over. Molecular research has identified an extended global host range and significant genetic diversity. However, Australia has reported a reduced host range (avian, horse, and human) with a dominance of clonal strains, denoted ST24. To better understand the widespread of this strain type in Australia, multilocus sequence typing (MLST) and ompA genotyping were applied on samples from a range of hosts (avian, equine, marsupial, and bovine) from Australia. MLST confirms that clonal ST24 strains dominate infections of Australian psittacine and equine hosts (82/88; 93.18%). However, this study also found novel hosts (Australian white ibis, King parrots, racing pigeon, bovine, and a wallaby) and demonstrated that strain diversity does exist in Australia. The discovery of a C. psittaci novel strain (ST306) in a novel host, the Western brush wallaby, is the first detection in a marsupial. Analysis of the results of this study applied a multidisciplinary approach regarding Chlamydia infections, equine infectious disease, ecology, and One Health. Recommendations include an update for the descriptive framework of C. psittaci disease and cell biology work to inform pathogenicity and complement molecular epidemiology.

Seroprevalence of Chlamydia abortus infection in yak (Bos grunniens) in Tibet, China

Chlamydia spp. are prevalent zoonotic pathogens that infect a wide variety of host species. Chlamydia abortus (C. abortus) infection in yaks has been reported in Gansu and Qinghai province, China. However, no data about C. abortus infection are available in yaks in Tibet, China. A total of 938 serum samples was collected from yaks in Tibet, China and specific antibodies against C. abortus were detected by the enzyme-linked immunosorbent assay (ELISA). The results showed that the overall seroprevalence of C. abortus in yaks was 104/938 (11.1 %, 95 % confidence interval [CI] 9.1–13.1). The prevalence in female and male yaks was 59/556 (10.6 %, 95 % CI 8.0-13.2) and 45/382 (11.8 %, 95 % CI 8.5–15.0), respectively with no significant difference (p > 0.05). The seroprevalence of antibodies to C. abortus in yaks ranged from 8.0 to 18.2 % among the six different areas, and the difference was also without statistical significance (p > 0.05). The prevalence among different age groups ranged from 7.0 to 15.9 %, with a higher prevalence among 1 to 2 years age category. The results demonstrate the presence of C. abortus infection in yaks in Tibet and may pose a risk for the general yak populations in addition to its potential impact on public health and the local Tibetan economy. To our knowledge, this is the first seroprevalence survey of C. abortus in yaks in Tibet, China.

Chlamydiae from Down Under: The Curious Cases of Chlamydial Infections in Australia

In Australia, the most researched and perhaps the most successful chlamydial species are the human pathogen Chlamydia trachomatis, animal pathogens Chlamydia pecorum and Chlamydia psittaci. C. trachomatis remains the leading cause of sexually transmitted infections in Australians and trachoma in Australian Indigenous populations. C. pecorum is globally recognised as the infamous koala and widespread livestock pathogen, whilst the avian C. psittaci is emerging as a horse pathogen posing zoonotic risks to humans. Certainly not innocuous, the human infections with Chlamydia pneumoniae seem to be less prevalent that other human chlamydial pathogens (namely C. trachomatis). Interestingly, the complete host range for C. pecorum and C. psittaci remains unknown, and infections by other chlamydial organisms in Australian domesticated and wildlife animals are understudied. Considering that chlamydial organisms can be encountered by either host at the human/animal interface, I review the most recent findings of chlamydial organisms infecting Australians, domesticated animals and native wildlife. Furthermore, I also provide commentary from leading Australian Chlamydia experts on challenges and future directions in the Chlamydia research field.