Genetic diversity and occurrence of Eimeria species causing cattle coccidiosis in Kashmir, India.

This study focuses on the occurrence, identification, and molecular characterization of Eimeria species causing coccidiosis in cattle in the Kashmir Valley, India. Coccidiosis, caused by apicomplexan parasites of the genus Eimeria, poses a significant threat to global cattle farming. Conventional techniques for identification, which rely on the morphology of sporulated oocysts, have drawbacks, leading to the adoption of molecular techniques to accurately delimit species. A total of 190 cattle were sampled in nine farms and parasitological examination revealed an occurrence of 45.7% for Eimeria spp. Molecular analysis using PCR and sequencing identified three predominant species: E. zuernii, E. alabamensis, and E. bovis. The study highlights the widespread occurrence of these species globally, as supported by previous research conducted in Bangladesh, Austria, Egypt, and Brazil. The phylogenetic analysis based on internal transcribed spacer (ITS-1) gene sequences revealed distinct clusters for E. zuernii and E. bovis, while E. alabamensis formed a separate clade. The genetic diversity and phylogenetic connections provide insights into the evolutionary relationships among these Eimeria species. This study contributes valuable information for understanding the epidemiology and genetic diversity of cattle coccidiosis in the Kashmir Valley, emphasizing the importance of molecular characterization for accurate species identification.

Occurrence and factors associated with Cryptosporidium infection in livestock in three districts of Zambia.

Cryptosporidium is one of the most important enteric diarrhoeal parasites that infect humans and animals worldwide. The current study investigated the occurrence and risk factors associated with Cryptosporidium infection in ruminants aged ≤6 months in Monze, Mumbwa, and Lusaka districts of Zambia. Faecal samples were collected from 328 calves, 190 lambs, and 245 goat kids and analysed for Cryptosporidium oocysts using modified Ziehl Neelsen staining. A closed structured questionnaire was used to obtain epidemiological characteristics and potential risk factors for Cryptosporidium infection. The overall occurrence of Cryptosporidium was 7.9% (60/763), while that in calves, lambs and goat kids was 14.5% (47/328), 5.3% (10/190), and 1.2% (3/245) respectively. Watery/pasty stool and sampling during the rainy season were independently associated with increased risk of infection. In calves, the odds of infection increased during the rainy season, while daily kraal cleaning reduced the infection risk. Lambs showed increased odds of infection with pasty/watery stool and male sex, whereas the wearing of protective clothing by handlers significantly reduced the risk. There were district variations in infection occurrence with Mumbwa district having higher prevalence. The findings of this study show that livestock in Zambia continue to be frequently infected with Cryptosporidium. Protective measures and appropriate farm cleanliness should be implemented in control of this infection. Regional and host-species-specific variations emphasize the need for targeted interventions. These findings, therefore, contribute to effective strategies for Cryptosporidium control, promoting good livestock health and management.

Morphological and molecular data confirm the occurrence of Paramphistomum leydeni (Trematoda: Paramphistomidae) in ruminants from Southern Brazil.

Species belonging to the family Paramphistomidae Fischoeder, 1901, commonly known as "rumen flukes", are a group of parasites frequently related to Brazilian livestock production. They inhabit the digestive tract of ruminants and have recognized pathogenicity during the early stages of infection, which can be responsible for economic losses. These trematodes are often associated with Southern Brazil, a region heavily focused on animal farming, which also makes it ideal for the life cycle of paramphistomes. Despite their aforementioned importance, studies regarding their distribution, molecular taxonomy and biology are still scarce in the country. In the present study, rumen flukes collected from cattle (n = 22) and sheep (n = 3) from 9 batches of ruminants from the cities of Jaguarão, Pelotas and Rio Grande, state of Rio Grande do Sul, Brazil, between May and July 2022, were subjected to morphological and molecular study. The microscopic analysis of histological and manual cuts revealed diagnostical traits compatible with Paramphistomum leydeni Näsmark, 1937, including the presence of tegumental papillae, pharynx of the liorchis type and acetabulum of the leydeni type. Molecular data corroborated the morphological identification, with ITS-2 and cox-1 sequences here obtained presenting 100% and 96.8-99.8% similarity, respectively, to P. leydeni samples previously characterized in different countries from Asia, Europe, and South America. Intensity of infection ranged from 5 to 458 and 1 to3 specimens of P. leydeni in sampled cattle and sheep, respectively. The present study contributes to a better understanding of the taxonomy of the flukes involved in cattle and sheep paramphistomosis in Brazil, suggesting that P. leydeni could be the main paramphistome species found in ruminants in the studied region.

Avian Influenza A(H5N1) Virus among Dairy Cattle, Texas, USA.

During March and April 2024, we studied dairy cattle specimens from a single farm in Texas, USA, using multiple molecular, cell culture, and next-generation sequencing pathogen detection techniques. Here, we report evidence that highly pathogenic avian influenza A(H5N1) virus strains of clade 2.3.4.4b were the sole cause of this epizootic.

Prevalence, clinico-epidemiological features, and molecular characterization of bovine papular stomatitis virus in cattle in Iraq.

Bovine papular stomatitis virus (BPSV) is a parapoxvirus that infects cattle, causing skin lesions on the udder and mouth. There have been few studies on the prevalence and molecular characteristics of BPSV in Iraq. Here, we describe the prevalence, phylogenetic analysis, and clinico-epidemiological features of BPSV in cattle in Al-Qadisiyah, Iraq. A total of 264 animals were examined for teat and oral lesions, and BPSV was detected by PCR in 79.9% (211/264) of cattle and calves with skin lesions. The lesions included ulcers, papules, and scabby proliferative areas. The BPSV strains from Iraq clustered phylogenetically with BPSV strains detected in the USA. Further studies are needed to explore the evolution and epidemiology of this virus in the region.

Outbreak of aflatoxicosis in a dairy herd induced depletion in milk yield and high abortion rate in Pakistan.

This case report investigated the outbreak of aflatoxicosis in a dairy herd in Pakistan, which resulted in 30 abortions of 40 confirmed (75%) pregnant cows in a period of 35 days and in 18.8% depression of farm average milk production for the entire herd. The analysis of the concentrate feed of the total mixed ration (TMR), using enzyme-linked immunosorbent assay (ELISA) procedures from two different local laboratories, indicated concentrations of 60 µg/kg dry matter (DM) of aflatoxin B1 (AFB1) and 100 µg/kg DM of total aflatoxins (AFs: sum of B1, B2, G1 and G2). Subsequently, a confirmatory analysis with a more sensitive and validated multi-metabolite liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was performed. This analysis detected a concentration of total AFs in the TMR of 166 µg/kg DM ± 3.5 (AFB1:134, AFB2:17.4 and AFM1:14.9 µg/kg DM). The concentrate feed (55% of the TMR DM) was confirmed as a source of contamination, presenting a concentration >29 times higher than the EU-maximum limit value (5.68 µg/kg DM). Additionally, the multi-mycotoxin analysis evidenced the co-occurrence of 81 other toxic and potentially toxic fungal metabolites in the fed TMR. After replacing the contaminated concentrate feed with feedstuffs of the same formulation but from a new charge of ingredients, the abortion episodes ceased, and milk production increased significantly. In conclusion, the data of this case report suggest that AFs may be associated with pregnancy losses in dairy cattle and milk production depression. From the public health perspective, the data also indicate the need for a more careful examination of dairy animal feed in Pakistan. Since the high concentration of AFB1 detected in feed and considering the literature-reported transfer rates (1-6%) of this toxin to AFM1 (carcinogen for humans) in milk, the milk produced during the outbreak period is expected to be contaminated with AFM1, which raises public health concerns.

First detection of tick-borne encephalitis virus (TBEV) in raw milk samples in North-Western Iran.

Tick-borne encephalitis virus (TBEV) is a significant cause of flaviviral infections affecting the human central nervous system, primarily transmitted through tick bites and the consumption of unpasteurized milk. This study aimed to assess the prevalence of TBEV and identify new natural foci of TBEV in livestock milk. In this cross-sectional study, unpasteurized milk samples were collected from livestock reared on farms and analysed for the presence and subtyping of TBEV using nested reverse transcription-polymerase chain reaction , alongside the detection of anti-TBEV total IgG antibodies using ELISA. The findings revealed that the highest prevalence of TBEV was observed in goat and sheep milk combined, whereas no TBEV was detected in cow milk samples. All identified strains were of the Siberian subtype. Moreover, the highest prevalence of anti-TBEV antibodies was detected in sheep milk. These results uncover new foci of TBEV in Iran, underscoring the importance of thermal processing (pasteurization) of milk prior to consumption to mitigate the risk of TBEV infection.

Complete coding region sequence analyses and antigenic characterization of emerging lineage G-IX of foot- and-mouth disease virus serotype Asia1.

Foot-and-mouth disease Virus (FMDV) serotype Asia1 is prevalent in the Indian subcontinent, with only G-III and G-VIII reported in India until 2020. However, in 2019, a novel genetic group within serotype Asia1, designated as G-IX, emerged in Bangladesh, followed by its detection in India in 2020. This report presents analyses of the complete coding region sequences of the G-IX lineage isolates. The length of the open reading frame (ORF) of the two G-IX isolates was 6990 nucleotides without any deletion or insertion. The G-IX isolates showed the highest sequence similarity with an isolate of G-III at the ORF, L, P2, and P3 regions, and with an isolate of G-VIII at the P1 region. Phylogenetic analysis based on the capsid region (P1) supports the hypothesis that G-VIII and G-IX originated from a common ancestor, as speculated earlier. Further, VP1 region-based phylogenetic analyses revealed the re-emergence of G-VIII after a gap of 3 years. One isolate of G-VIII collected during 2023 revealed a codon insertion in the G-H loop of VP1. The vaccine matching studies support the suitability of the currently used Indian vaccine strain IND63/1972 to contain outbreaks due to viruses belonging to G-IX.

First detection of Tetraparvovirus ungulate 1 in diseased cattle (Chinese Simmental) from Hunan province, China.

Tetraparvovirus is an emerging parvovirus infecting a variety of mammals and humans, and associated with human diseases including severe acute respiratory infection and acute encephalitis syndrome. In the present study, a Tetraparvovirus ungulate 1 (formerly known as bovine hokovirus) strain HNU-CBY-2023 was identified and characterized from diseased Chinese Simmental from Hunan province, China. The nearly complete genome of HNU-CBY-2023 is 5346 nt in size and showed genomic identities of 85-95.5% to the known Tetraparvovirus ungulate 1 strains from GenBank, indicating a rather genetic variation. Phylogenetic and genetic divergence analyses indicated that Tetraparvovirus ungulate 1 could be divided into two genotypes (I and II), and HNU-CBY-2023 was clustered into genotype II. This study, for the first time, identified Tetraparvovirus ungulate 1 from domestic cattle from mainland China, which will be helpful to understand the prevalence and genetic diversity of Tetraparvovirus ungulate 1.

Change in the incidence of stillbirth in Japanese Black cattle during the animal movement restrictions and suspended insemination.

We aimed to characterize the change in the incidence of stillbirth (IS) in Japanese Black cattle during and after animal movement restrictions and suspended insemination because of a foot-and-mouth disease (FMD) outbreak in Miyazaki Prefecture in 2010. Calving data from 2006 to 2018 were collected from approximately 900 farms. Post-FMD period was divided into three based on the median IS per month (1.80%): period 1 (May 2011 to February 2013), period 2 (March 2013 to August 2015), and period 3 (September 2015 to December 2018). The ISs were similar during the Pre-FMD period and Post-FMD period 1, then substantially decreased during Post-FMD period 2 (p < .05), before returning to the value before the FMD outbreak period during Post-FMD period 3. Compared with the Pre-FMD period, Post-FMD period 1 was associated with a higher proportion of calvings by primiparous cows and Post-FMD period 2 was associated with a smaller number of calvings per month (p < .05). There were high ISs in primiparous cows during the Pre-FMD period, Post-FMD period 1, and Post-FMD period 3 (p < .05), but not during Post-FMD period 2. In summary, after the animal movement restrictions and suspended insemination introduced because of the FMD outbreak, the IS temporarily decreased and consequently returned to the pre-FMD level.

Leptospirosis as a cause of infertility in Uruguayan beef cattle.

Leptospirosis, caused by pathogenic spirochetes of the genus Leptospira spp., is a globally significant zoonotic disease that affects humans and animals. In cattle, leptospirosis is associated not only with overt clinical manifestations but also with reproductive diseases, including infertility. This study assesses the potential correlation between leptospirosis and infertility in Uruguayan beef cattle. A case-control study involved 31 beef herds with no prior history of Leptospira vaccination. In each herd, veterinarians identified 10 non-pregnant (cases) and 25 pregnant cows (controls) using ultrasound, and blood and urine samples were collected from each cow. Serological diagnosis was performed using the Microscopic Agglutination Test (MAT), and quantitative PCR (qPCR) was used to assess Leptospira excretion. Additionally, antibodies against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis (IBR) were tested. The results demonstrated an association between seropositivity to the Sejroe serogroup (cut-off 1:200) and infertility in cattle (OR=1.31; p-value=0.06). Furthermore, the level of Leptospira excretion (qPCR) in urine was associated with increased infertility risk, with cows excreting over 100 copies per mL of urine having the highest odds of infertility (OR=2.34; p-value<0.01). This study suggests a potential association between leptospirosis and infertility in Uruguayan beef cattle, emphasizing the importance of both serological and molecular diagnostics for assessing reproductive health in cattle herds. Future research should explore the impact of Leptospira serogroups on other reproductive disorders in cattle.

Leveraging artificial intelligence and software engineering methods in epidemiology for the co-creation of decision-support tools based on mechanistic models.

Epidemiological modeling is a key lever for infectious disease control and prevention on farms. It makes it possible to understand the spread of pathogens, but also to compare intervention scenarios even in counterfactual situations. However, the actual capability of decision makers to use mechanistic models to support timely interventions is limited. This study demonstrates how artificial intelligence (AI) techniques can make mechanistic epidemiological models more accessible to farmers and veterinarians, and how to transform such models into user-friendly decision-support tools (DST). By leveraging knowledge representation methods, such as the textual formalization of model components through a domain-specific language (DSL), the co-design of mechanistic models and DST becomes more efficient and collaborative. This facilitates the integration of explicit expert knowledge and practical insights into the modeling process. Furthermore, the utilization of AI and software engineering enables the automation of web application generation based on existing mechanistic models. This automation simplifies the development of DST, as tool designers can focus on identifying users' needs and specifying expected features and meaningful presentations of outcomes, instead of wasting time in writing code to wrap models into web apps. To illustrate the practical application of this approach, we consider the example of Bovine Respiratory Disease (BRD), a tough challenge in fattening farms where young beef bulls often develop BRD shortly after being allocated into pens. BRD is a multi-factorial, multi-pathogen disease that is difficult to anticipate and control, often resulting in the massive use of antimicrobials to mitigate its impact on animal health, welfare, and economic losses. The DST developed from an existing mechanistic BRD model empowers users, including farmers and veterinarians, to customize scenarios based on their specific farm conditions. It enables them to anticipate the effects of various pathogens, compare the epidemiological and economic outcomes associated with different farming practices, and decide how to balance the reduction of disease impact and the reduction of antimicrobial usage (AMU). The generic method presented in this article illustrates the potential of artificial intelligence (AI) and software engineering methods to enhance the co-creation of DST based on mechanistic models in veterinary epidemiology. The corresponding pipeline is distributed as an open-source software. By leveraging these advancements, this research aims to bridge the gap between theoretical models and the practical usage of their outcomes on the field.

Bird Flu Outbreak in Dairy Cows Is Widespread, Raising Public Health Concerns.

This Medical News article discusses the current H5N1 avian influenza outbreak in US dairy cattle and its implications for occupational and public health.

Accumulation of resistance genes in Salmonella Typhimurium transmitted between poultry and dairy farms increases the risk to public health.

Salmonella Typhimurium is a zoonotic pathogen that poses a major threat to public health. This generalist serotype can be found in many hosts and the environment where varying selection pressures may result in the accumulation of antimicrobial resistance determinants. However, the transmission of this serotype between food-producing hosts, specifically between poultry layer flocks and nearby dairy herds, was never demonstrated. We investigated an outbreak at a dairy in Israel to determine the role of nearby poultry houses to be sources of infection. The 2-month outbreak resulted in a 47% mortality rate among 15 calves born in that period. Routine treatment of fluid therapy, a nonsteroidal anti-inflammatory, and cefquinome was ineffective, and control was achieved by the introduction of vaccination of dry cows against Salmonella (Bovivac S, MSD Animal Health) and a strict colostrum regime. Whole genome sequencing and antimicrobial sensitivity tests were performed on S. Typhimurium strains isolated from the dairy (n = 4) and strains recovered from poultry layer farms (n = 10). We identified acquired antimicrobial-resistant genes, including the blaCTX-M-55 gene, conferring resistance to extended-spectrum cephalosporins, which was exclusive to dairy isolates. Genetic similarity with less than five single nucleotide polymorphism differences between dairy and poultry strains suggested a transmission link. This investigation highlights the severe impact of S. Typhimurium on dairy farms and the transmission risk from nearby poultry farms. The accumulation of potentially transferable genes conferring resistance to critically important antimicrobials underscores the increased public health risk associated with S. Typhimurium circulation between animal hosts.IMPORTANCESalmonella Typhimurium is one of the major causes of food-borne illness globally. Infections may result in severe invasive disease, in which antimicrobial treatment is warranted. Therefore, the emergence of multi-drug-resistant strains poses a significant challenge to successful treatment and is considered one of the major threats to global health. S. Typhimurium can be found in a variety of animal hosts and environments; however, its transmission between food-producing animals, specifically poultry layers flocks and dairy herds, was never studied. Here, we demonstrate the transmission of the pathogen from poultry to a nearby dairy farm. Alarmingly, the multi-drug-resistant strains collected during the outbreak in the dairy had acquired resistance to extended-spectrum cephalosporins, antibiotics critically important in treating Salmonellosis in humans. The findings of the study emphasize the increased risk to public health posed by zoonotic pathogens' circulation between animal hosts.

Epidemiology of Anaplasma species amongst cattle in Africa from 1970 to 2022: A systematic review and meta-analysis.

Tick-borne pathogens of the genus Anaplasma cause anaplasmosis in livestock and humans, impacting health and livelihoods, particularly in Africa. A comprehensive review on the epidemiology of Anaplasma species is important to guide further research and for implementation of control approaches. We reviewed observational studies concerning Anaplasma species amongst cattle in Africa. Peer-reviewed studies published in PubMed, Google Scholar, and Web of Science - from database inception to 2022 - were searched. The quality of individual studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool and the pooled prevalences by diagnostic method were estimated using random-effects models. Heterogeneity across the studies was tested and quantified using the Cochran's Q statistic and the I2 statistic. Potential sources of heterogeneity were investigated by subgroup analysis. A total of 1117 records were retrieved and at the end of the screening, 149 records (155 studies) were eligible for this meta-analysis. The occurrence of Anaplasma species was reported in 31/54 countries in all regions. Seven recognised species (A. marginale, A. centrale, A. phagocytophilum, A. platys, A. capra, A. bovis, A. ovis) and nine uncharacterised genotypes (Anaplasma sp. Hadesa; Anaplasma sp. Saso; Anaplasma sp. Dedessa; Anaplasma sp. Mymensingh; Anaplasma sp. Lambwe-1; Candidatus Anaplasma africae; Anaplasma sp.; Candidatus Anaplasma boleense) were reported in African cattle. Anaplasma marginale was the most frequently reported (n=144/155 studies) and the most prevalent species (serology methods 56.1%, 45.9-66.1; direct detection methods 19.9%, 15.4-24.7), followed by A. centrale (n=26 studies) with a prevalence of 8.0% (95% CI: 4.8-11.9) and A. platys (n=19 studies) with prevalence of 9.7% (95% CI: 5.4-15.2). Anaplasma marginale, A. centrale and A. platys were reported in all Africa's regions, while A. ovis and A. capra were reported only in the northern and central regions. The uncharacterised Anaplasma taxa were mostly detected in the eastern and southern regions. Subgroup analysis showed that significant determinants for A. marginale exposure (serology) were geographical region (p=0.0219), and longitude (p=0.0336), while the technique employed influenced (p<0.0001) prevalence in direct detection approaches. Temperature was the only significant variable (p=0.0269) for A. centrale. These findings show that various Anaplasma species, including those that are zoonotic, circulate in African cattle. There is need for more genetic and genome data, especially for unrecognised species, to facilitate effective identification, improve livestock and minimise the health risk in human populations. Additional epidemiological data including pathogen occurrence, tick vectors and host range, as well as pathogenicity are essential.

High frequency of multidrug-resistant Escherichia coli from cattle in the Cerrado and Pantanal biomes of Brazil.

The indiscriminate use of antimicrobials has led to the emergence of resistant bacteria, especially pathogenic strains of Escherichia coli, which are associated with diseases in animals and humans. The aim of the present study was to characterize E. coli isolates in calves with regards to the presence of virulence genes and investigate the resistance of the isolates to different antimicrobials. Between 2021 and 2023, 456 fecal samples were collected from calves in the Pantanal and Cerrado biomes of the state of Mato Grosso do Sul, Brazil. All samples were subjected to microbiological analysis and disc diffusion antibiogram testing. The polymerase chain reaction method was used to detect virulence genes. Bacterial growth was found in 451 of the 456 samples and biochemically identified as Escherichia coli. All 451 isolates (100 %) exhibited some phenotypic resistance to antimicrobials and 67.62 % exhibited multidrug resistance. The frequency of multidrug-resistant isolates in the Cerrado biome was significantly higher than that in the Pantanal biome (p = 0.0001). In the Cerrado, the most common pathotype was Shiga toxin-producing Escherichia coli (STEC) (28 %), followed by toxigenic Escherichia coli (ETEC) (11 %), enterohemorrhagic Escherichia coli (EHEC) (8 %) and enteropathogenic Escherichia coli (EPEC) (2 %). In most cases, the concomitant occurrence of pathotypes was more common, the most frequent of which were ETEC + STEC (33 %), ETEC + EHEC (15 %) and ETEC + EPEC (3 %). The STEC pathotype (30 %) was also found more frequently in the Pantanal, followed by EHEC (12 %), ETEC (9 %) and EPEC (6 %). The STEC pathotype had a significantly higher frequency of multidrug resistance (p = 0.0486) compared to the other pathotypes identified. The frequency of resistance was lower in strains from the Pantanal biome compared to those from the Cerrado biome. Although some factors are discussed in this paper, it is necessary to clarify the reasons for this difference and the possible impacts of these findings on both animal and human health in the region.

The Transmission of Animal African Trypanosomiasis in Two Districts in the Forest Zone of Ghana.

Animal African trypanosomiasis, also known as nagana, is caused by Trypanosoma species, which cause significant clinical diseases and lead to losses in animal production. We carried out a cross-sectional survey to investigate the composition of vectors and parasite diversity in two districts in the eastern region of Ghana where pigs and cattle were exposed to tsetse bites. We performed cytochrome c oxidase subunit 1 polymerase chain reaction (PCR) to identify tsetse species and internal transcribed spacer 1 PCR to identify Trypanosoma species. Also, we investigated the source of tsetse blood meal based on mitochondrial cytochrome b gene sequence analysis. A total of 229 tsetse, 65 pigs, and 20 cattle were investigated for trypanosomes. An overall vector density of 4.3 tsetse/trap/day was observed. A trypanosome prevalence of 58.9% (95% CI = 52.5-65.1%), 46.2% (95% CI = 34.6-58.1%), and 0.0% (95% CI = 0.0-16.1%) in tsetse, pigs, and cattle, respectively, was detected. Trypanosoma congolense was predominant, with a prevalence of 33.3% (95% CI = 73.3-86.5%) in tsetse. There was evidence of multiple infections in tsetse and pigs. Approximately 39% of the tsetse were positive for multiple infections of T. congolense and Trypanosoma simiae. Parasite prevalence in pigs across the communities was high, with significant differences associated between locations (χ2 = 28.06, 95% CI = 0.05-0.81, P = 0.0009). Tsetse blood meal analysis revealed feeding on domestic Sus scrofa domesticus (pigs) and Phacochoerus africanus (warthogs). Infective tsetse may transmit trypanosomes to livestock and humans in the communities studied.

Anaplasmosis outbreaks in taurine and zebu cattle in Brazil: causes, treatments, and Anaplasma marginale genetic diversity.

This study aimed to investigate seven outbreaks of A. marginale infection in two regions of Brazil, affecting taurine, zebu, and crossbred cattle. We assessed the possible causes, treatment measures, and genetic diversity of A. marginale. These outbreaks occurred in two states (Goiás: outbreaks 1-7; Mato Grosso do Sul: outbreak 3), breeds (Holstein, Nellore, and crossbreed), age groups (beef cattle: 18-25 days old and 7-8 months; dairy cattle: 18-25 days old, 13-14 months, and cow after the first birth) and rearing systems (feedlot, pasture, pen in a wood shaving bedding system and compost bedded-pack barns). Metaphylactic or prophylactic treatments varied according to outbreak (imidocarb dipropionate: outbreaks 1-4 and 6; enrofloxacin: outbreaks 5 and 7; diminazene diaceturate: outbreak 5). In outbreaks 6 and 7, the packed cell volume was monitored. In all outbreaks, the practice of needle/syringe sharing was discontinued. For outbreaks 1-3, clinical signs and mortality (range, 4.8-13.3%) occurred 36-45 days after entry into the feedlot. In outbreak 4, A. marginale was diagnosed in 66.2% of the calves (bacteremia, 0-4.5%), with a mortality of 8.6%. Among nursing calves aged 60 days during outbreak 5, 53.8% were infected with A. marginale, with average bacteremia of 2.7% (range, 0-21.3%), and a mortality of 13.8%. In dairy heifers aged 14 months, raised in paddocks lacking vegetation cover and infested with R. microplus, then transitioned to a rotational grazing system also infested with R. microplus, the A. marginale bacteremia ranged from 3.2 to 6.7%, with a mortality of 20%. Before monitoring during outbreak 7, the mortality was 17.9%, but no further deaths were observed after monitoring initiation. In conclusion, possible causes triggering the outbreaks included primary tick infestation, needle/syringe sharing, and stress factors which may have affected the immunological statues of animals in the feedlots. Control measures performed in all outbreaks were effective. The partial msp4 gene sequences of A. marginale generated herein belonged to two haplotypes, but further research would be needed to investigate if this finding has any clinical significance.