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Bovine viral diarrhea virus (BVDV) is a pathogen of worldwide economic importance. In Uruguay, BVDV is endemic, with seroprevalence >80% at the farm level. This study analyzed 912 samples collected from January 2018 to October 2024 by reverse transcription PCR and sequencing, from calves with diarrhea, aborted fetuses, heifers with a history of abortions, and animals exhibiting symptoms of Mucosal Disease. This work summarizes ten years (2014–2024) of molecular epidemiology and evolution of BVDV. Analysis of the BVDV 5′UTR/Npro genomic region revealed that the BVDV-1a, 1e, 1i, and 2b subtypes circulate in Uruguay. BVDV-1a remains the most prevalent subtype, followed by BVDV-2b, whose prevalence has been increasing. Our previous studies revealed that BVDV-1a showed geographical diversification in Uruguay. In this work, evolutionary studies conducted with Npro genomic region showed that BVDV-2b is evolving at a substitution rate of 6.09 × 10−4 substitutions/site/year and has been introduced from Brazil in six separate events between 1870 and 1928, showing no geographical diversification. This work demonstrates that BVDV-1a and BVDV-2b are evolving differently in Uruguay. This evolutionary divergence is notable when comparing patterns observed in other countries where these subtypes circulate. Our findings provide crucial knowledge that should be considered for developing effective BVDV control measures in Uruguay.

Yellow lamb disease is an infrequent disease in sheep for which there is scant literature, and that has been reported in the US, Australia, New Zealand, South Africa and Europe, although anecdotal evidence indicates that it may have also been diagnosed in South America. The disease is produced by some strains of Clostridium perfringens type A that produce unusually high levels of alpha- toxin. Because C. perfringens type A is ubiquitous and is found in the intestine of most clinically healthy sheep, diagnosis of yellow lamb disease is challenging and requires quantitating the amount of this microorganism present in feces and/or intestinal content. Clinically, yellow lamb disease is characterized by depression, anemia, icterus and hemoglobinuria. Occasionally, sudden death may occur. Gross findings include generalized icterus, red urine in the bladder, enlarged, pale, and friable spleen, enlarged liver with an acinar pattern, and dark, swollen kidneys. Microscopically, yellow lamb disease is characterized by centrilobular necrosis of the liver, hemoglobinuria-associated acute tubular injury, splenic congestion, pulmonary congestion and edema. Although there are no vaccines specifically designed to prevent yellow lamb disease, several vaccines against the different types of C. perfringens may afford at least some level of protection against yellow lamb disease.

Leptospirosis is a neglected zoonosis with worldwide distribution. The causative agents are spirochete bacteria of the Leptospira genus, displaying huge diversity of serovars, the identity of which is critical for effective diagnosis and vaccination purposes. Among many other mammalian species, Leptospira infects cattle, eliciting acute signs in calves, and chronic disease in adult animals often leading to abortions. In South America, and including in Uruguay, beef and dairy export are leading sources of national income. Despite the importance of bovine health, food safety, and bovine-related dissemination of leptospirosis to humans, extremely limited information is available as to the identity of Leptospira species and serovars infecting cattle in Uruguay and the South American subcontinent. Here we report a multicentric 3-year study resulting in the isolation and detailed characterization of 40 strains of Leptospira spp. obtained from infected cattle. Combined serologic and molecular typing identified these isolates as L. interrogans serogroup Pomona serovar Kennewicki (20 strains), L. interrogans serogroup Canicola serovar Canicola (1 strain), L. borgpetersenii serogroup Sejroe serovar Hardjo (10 strains) and L. noguchii (9 strains). The latter showed remarkable phenotypic and genetic variability, belonging to 6 distinct serogroups, including 3 that did not react with a large panel of reference serogrouping antisera. Approximately 20% of cattle sampled in the field were found to be shedding pathogenic Leptospira in their urine, uncovering a threat for public health that is being largely neglected. The two L. interrogans serovars that we isolated from cattle displayed identical genetic signatures to those of human isolates that had previously been obtained from leptospirosis patients. This report of local Leptospira strains shall improve diagnostic tools and the understanding of leptospirosis epidemiology in South America. These strains could also be used as new components within bacterin vaccines to protect against the pathogenic Leptospira strains that are actually circulating, a direct measure to reduce the risk of human leptospirosis.

The only genus of the Francisellaceae family known to contain species pathogenic to mammals is Francisella, for which reported cases in the Southern Hemisphere have been limited to Australia. We describe severe necrotizing and inflammatory lesions and intralesional immunohistochemical identification of Francisella sp. lipopolysaccharide among aborted ovine fetuses 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.

Coxiella burnetii is a highly transmissible intracellular bacterium with a low infective dose that causes Q fever (coxiellosis), a notifiable zoonotic disease distributed worldwide. Livestock are the main source of C. burnetii transmission to humans, which occurs mostly through the aerogenous route. Although C. burnetii is a major abortifacient in small ruminants, it is less frequently diagnosed in aborting cattle. We report a case of C. burnetii abortion in a lactating Holstein cow from a dairy farm producing and selling artisanal cheese directly to consumers in Uruguay, and review the literature on coxiellosis as a bovine abortifacient in South America and as a milk-borne disease. The aborted cow had severe necrotizing placentitis with abundant intratrophoblastic and intralesional C. burnetii confirmed by immunohistochemistry and PCR. After primo-infection in cattle, C. burnetii remains latent in the lymph nodes and mammary glands, with milk being a significant and persistent excretion route. Viable C. burnetii has been found in unpasteurized milk and cheeses after several months of maturing. The risk of coxiellosis after the consumption of unpasteurized dairy products, including cheese, is not negligible. This report raises awareness on bovine coxiellosis as a potential food safety problem in on-farm raw cheese manufacturing and sales. The scant publications on abortive coxiellosis in cattle in South America suggest that the condition has probably gone underreported in all countries of this subcontinent except for Uruguay. Therefore, we also discuss the diagnostic criteria for laboratory-based confirmation of C. burnetii abortion in ruminants as a guideline for veterinary diagnosticians.

Despite its sociocultural and economic importance, dairy farming in Uruguay has not experienced a significant increase in cattle stocks in recent decades, partly due to low reproductive efficiency and a high risk of calf mortality. Neospora caninum is one of the primary abortive pathogens in dairy cattle; however, the economic losses caused by neosporosis in Uruguay remain uncalculated. This study aimed to assess the direct annual economic losses for the primary dairy sector (dairy farmers) due to abortions resulting from bovine neosporosis in the Uruguayan herd. An adjusted bioeconomic model was used to estimate the economic losses from early (second gestational trimester) or late (third gestational trimester) abortions, considering the Present Value (PV) of future production loss due to these abortions after deducting production costs (lost profits). The average economic loss per abortion due to neosporosis was US $ 868 (range 605–1,162) if the aborting cow remained in the herd without any additional abortions throughout its productive life and US$1,866 (range 782–2,825) if the cow was culled after the abortion. Individual losses varied based on the gestational stage and the age of the aborting cow, with the worst-case scenario being a late abortion in first-pregnancy heifers. The annual number of abortions due to neosporosis was estimated by considering the stock of cows and heifers of reproductive age at risk of abortion (pregnant) and the national seroprevalence of N. caninum in dairy herds, accounting for 90% vertical transmission and 10% horizontal transmission, with aborting seropositive dams representing 15 and 35%, respectively. The economic losses for the national herd were calculated by multiplying individual losses by the number of abortions across various simulated scenarios (second or third gestational trimester), adjusted according to sub-scenarios (with and without culling of the aborted cow). The estimated economic losses for the primary sector due to abortions occurring in 2018 totaled nearly US$ 12 million, which is attributed to the loss of offspring, delayed lactation, reduced productive life (fewer days in milk production/days of life), and early culling. These estimated losses reflect only the primary sector, excluding the secondary (industrial) and tertiary (services) sectors. In physical terms, abortions associated with neosporosis caused a total loss of 62 million L of milk, which is 3.3% of the volume industrialized annually in the country. The estimated losses did not account for profits lost by dairy farmers from beef production (i.e., breeding, fattening, and sale for slaughter of male calves from dairy breeds lost due to neosporosis) nor any indirect losses (for example, the loss of genetic merit, stunted growth of the national dairy stock, etc.). The characteristics of Uruguay’s grazing dairy production system require a tailored approach to estimating the economic impact of bovine diseases. This information can be used by farmers, veterinarians, and policymakers to evaluate the cost–benefit of implementing control and prevention strategies for bovine neosporosis at both the farm and national levels.

The reasons for culling dairy cows in Uruguay are largely unknown. This study aimed to describe the culling rates of dairy cows and identify the causes of cow culling in 12 commercial herds in Uruguay. We conducted a prospective longitudinal observational study from June 2019 to May 2020 on 12 dairy farms stratified by herd size. Six farms with 51–199 cows, five with 200–500 cows, and one farm with more than 500 cows in the departments of Colonia and San José were included. The cows were pure Holstein and Holstein–Jersey crossbreeds. The overall dairy cow population on these 12 farms was 3126 cows (range: 74–740 cows per farm). The data were analyzed using descriptive statistics. The total annual culling rate was 23.1% (721/3126), including sales to slaughter (18.1%; 565/3126), on-farm mortality (4.5%; 141/3126), and dairy sales (0.5%; 15/3126). Cow culling for slaughter because of health (including reproductive) problems represented 70.7% (510/721) of the overall culling rate, most of which were due to reproductive failure (29.3%, 211/721), mastitis (25.9%, 187/721), poor udder conformation (6.2%, 45/721), lameness (4.6%, 33/721), and other diseases (4.7%, 34/721). Mortality represented 19.6% (141/721) of the overall culling rate. Cow culling for slaughter due to health (including reproductive) problems and mortality constituted 90.3% (651/721) of the total culled cows. In conclusion, dairy cows were culled mainly due to illnesses that lead to slaughter or death. Implementing effective measures to improve reproductive rates, reduce mastitis and lameness, and prevent other diseases, such as leukosis, paratuberculosis, and digestive disorders in the studied population would reduce cow culling, increasing cow longevity, animal welfare, and farm profitability.

Bovine polyomavirus-1 (BoPyV-1, Epsilonpolyomavirus bovis) is widespread in cattle and has been detected in commercialized beef at supermarkets in the USA and Germany. BoPyV-1 has been questioned as a probable zoonotic agent with documented increase in seropositivity in people exposed to cattle. However, to date, BoPyV-1 has not been causally associated with pathology or disease in any animal species, including humans. Here we describe and illustrate pathological findings in an aborted bovine fetus naturally infected with BoPyV-1, providing evidence of its pathogenicity and probable abortigenic potential. Our results indicate that: (i) BoPyV-1 can cause severe kidney lesions in cattle, including tubulointerstitial nephritis with cytopathic changes and necrosis in tubular epithelial cells, tubular and interstitial inflammation, and interstitial fibroplasia; (ii) lesions are at least partly attributable to active viral replication in renal tubular epithelial cells, which have abundant intranuclear viral inclusions; (iii) BoPyV-1 large T (LT) antigen, resulting from early viral gene expression, can be detected in infected renal tubular epithelial cells using a monoclonal antibody raised against Simian Virus-40 polyomavirus LT antigen; and (iv) there is productive BoPyV-1 replication and virion assembly in the nuclei of renal tubular epithelial cells, as demonstrated by the ultrastructural observation of abundant arrays of viral particles with typical polyomavirus morphology. Altogether, these lesions resemble the “cytopathic-inflammatory pathology pattern” proposed in the pathogenesis of Human polyomavirus-1-associated nephropathy in immunocompromised people and kidney allograft recipients. Additionally, we sequenced the complete genome of the BoPyV-1 infecting the fetus, which represents the first whole genome of a BoPyV-1 from the Southern Hemisphere. Lastly, the BoPyV-1 strain infecting this fetus was isolated, causing a cytopathic effect in Madin–Darby bovine kidney cells. We conclude that BoPyV-1 is pathogenic to the bovine fetus under natural circumstances. Further insights into the epidemiology, biology, clinical relevance, and zoonotic potential of BoPyV-1 are needed.

Viral infections affecting cattle lead to economic losses to the livestock industry worldwide, but little is known about the circulation, pathogenicity and genetic diversity of enteric bovine astrovirus (BoAstV) in America. The aim of this work was to describe the prevalence and genetic diversity of enteric BoAstV in dairy cattle in Uruguay. A total of 457 fecal and 43 intestinal contents from dairy calves were collected between July 2015 and May 2017 and tested by RT-PCR, followed by sequencing and phylogenetic analyses of the polymerase and capsid regions. Twenty-six percent (128/500) of the samples were positive. Three different species within the Mamastrovirus genus were identified, including Mamastrovirus 28, Mamastrovirus 33 (3 samples each) and an unclassified Mamastrovirus species (19 samples). The unclassified species was characterized as a novel Mamastrovirus species. BoAstV circulates in Uruguayan dairy cattle with a high genetic diversity. The eventual clinicopathological significance of enteric BoAstV infection in cattle needs further investigation.