Spontaneous intoxication of sheep by the pollen beetle Astylus atromaculatus: 4 outbreaks in Uruguay and Argentina

Astylus atromaculatus Blanchard is a native beetle of South America that feeds on pollen. During the summer of 2022-2023 in Argentina and Uruguay, an explosive infestation of these insects occurred in pastures in which ruminants were grazing. This was believed to be associated with a severe drought, which had significantly reduced the flowering of crops. Three farms in Uruguay and one in Argentina were visited to examine the flocks and perform autopsies. Affected sheep had watery diarrhea, anorexia, depression, and ruminal atony. The average morbidity, mortality, and case fatality rates were 7.5%, 4.3%, and 68%, respectively. The main gross findings in all animals were in the jejunum; the serosa had multifocal hemorrhages, and the mucosa was necrotic and covered by a pseudomembrane. Microscopically, the mucosa had partial-to-complete necrosis of the lamina propria, as well as loss of villus and crypt epithelium with neutrophilic infiltration. Overlying the necrotic mucosa was a pseudomembrane of fibrin, cell debris, desquamated epithelial cells, degenerate neutrophils, and bacteria. Many specimens of A. atromaculatus were in all paddocks in which sheep grazed, as well as in the ruminal content of the autopsied animals.

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

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

Pollen beetle (Astylus atromaculatus)-associated gastroenteric disease in cattle: report of 6 natural outbreaks

Astylus atromaculatus is a pollen beetle native to South America, commonly found in crop flowers. Experimental intoxication of sheep and guinea pigs by this beetle resulting in fibrinonecrotizing enteritis has been reported. We describe here 6 natural outbreaks of intoxication in cattle associated with consumption of alfalfa (5 of 6) and mixed native (1 of 6) pastures heavily contaminated with A. atromaculatus. The outbreaks occurred during the summer (January-February) of 2023 in Argentina (n = 4) and Uruguay (n = 2), in beef cattle under extensive or semi-extensive rearing systems, with overall cumulative incidence and mortality of 22.3% and 17.8%, respectively. The main clinical signs included acute onset of anorexia, lethargy, hyperthermia, hindlimb weakness, reluctance to move, and diarrhea, for up to 15 d. In 2 outbreaks, sudden death was observed. Eight Hereford, Angus, and/or crossbreed heifers, cows, steers, and/or calves were autopsied. Gross and microscopic findings included multifocal necrosis with fibrinous pseudomembranes in the forestomachs and/or small and large intestines. Fragments or whole specimens of A. atromaculatus were identified in the ruminal content of all animals. Testing for multiple gastroenteric pathogens was negative as was testing of A. atromaculatus for cantharidin and batrachotoxin. GC-MS and LC-MS/MS performed on the beetles did not identify any known toxic compounds. Based on the exposure to A. atromaculatus-contaminated pasture, gross and microscopic lesions, and negative results of all testing for multiple gastroenteric pathogens, a diagnosis of intoxication by A. atromaculatus is proposed. Disease caused by A. atromaculatus consumption has not been reported previously in cattle, to our knowledge.

A meta-analysis of the effects of colostrum heat treatment on colostral viscosity, immunoglobulin G concentration, and the transfer of passive immunity in newborn dairy calves

Newborn ruminants depend on colostrum intake immediately after birth to obtain immunoglobulins for effective transfer of passive immunity (TPI). As colostrum may also be a vehicle of infectious agents, heat treatment of raw colostrum is a practice aimed at eliminating or reducing its pathogen load. Despite the usefulness of heat treatment in preventing the transmission of infectious colostrum-borne diseases, heat treatment of colostrum may have some side effects. A systematic review and meta-analysis were conducted to summarize the effects of colostrum heat treatment on colostral viscosity and IgG concentration, and serum IgG concentration as a proxy for TPI in newborn calves fed raw versus heat-treated colostrum. Moderators were studied to identify sources of heterogeneity. Literature databases were searched for peer-reviewed articles published between 1946 and 2022. A Master of Science thesis was also included. Five, 21, and 19 original publications were quantitatively evaluated in 3 separate meta-analyses, based on predefined selection criteria. Two-level and 3-level random-effects meta-analysis revealed a significant overall effect of heat treatment on colostral viscosity and IgG concentration, and serum IgG concentration in newborns. Heat-treated colostrum had significantly higher viscosity (21.0 cP, 95% CI: 3.8 to 38.2) and lower IgG concentration (-7.4 g/L, 95% CI: -11.1 to -3.7) compared with raw colostrum. Overall, newborn calves fed heat-treated colostrum had higher serum IgG concentrations (2.8 g/L, 95% CI: 1.4 to 4.0) 24-48 h after birth than those fed with raw colostrum. Particularly, this positive effect on the serum IgG concentrations was seen when colostrum was heat-treated at ≤60°C (2.9 g/L, 95% CI: 0.9 to 4.2) and when the standard low-temperature low-time (LTLT) method was used for heat treatment (2.6 g/L, 95% CI: 0.1 to 5.1). Colostrum treated at >60-63.5°C tended to have higher viscosity (275.6 cP, 95% CI: -37.9 to 589.3) and had lower IgG concentration (-21.7 g/L, 95% CI: -27.3 to -16.1). Calves fed colostrum treated at this temperature range had significantly lower serum IgG (-4.2 g/L, 95% CI: -7.9 to -0.4) compared with those fed raw colostrum. Heat treatment of colostrum at 72-76°C was not associated with a significant increase in colostral viscosity (6.3 cP, 95% CI: -324.3 to 336.9) nor a reduction in IgG colostral concentration (-13.1 g/L, 95% CI: -26.5 to 0.2), but calves fed colostrum treated at this temperature range had a significant reduction in serum IgG (-11.3 g/L, 95% CI: -17.1 to -5.4). Feeding newborn calves with colostrum heat-treated at ≤60°C by the standard LTLT method, particularly within 2 h after birth, resulted in increased serum IgG concentration at 24-48 h of age. Importantly, delaying feeding of heat-treated colostrum to newborns beyond 2 h of age resulted in no significant difference in IgG serum levels compared with feeding raw colostrum, highlighting the importance of early administration of heat-treated colostrum to favor TPI. On-farm colostrum heat treating should achieve an equilibrium between pathogen elimination and the preservation of colostral immunoglobulins while minimizing undesired increases in viscosity. The beneficial effects of colostrum heat treatment on TPI can be negligible if colostrum feeding is not performed within 2 h after birth.

Canine leproid granuloma caused by a member of the Mycobacterium tuberculosis complex

Canine leproid granuloma (CLG) is a chronic form of dermatitis that has been associated with nontuberculous mycobacterial infections in Africa, Oceania, the Americas, and Europe. We report here a case of CLG associated with a member of the Mycobacterium tuberculosis complex (MTBC), which could be of public health concern. An 8-y-old pet dog developed 0.5-1-cm diameter, raised, firm, nonpruritic, alopecic, painless skin nodules on the external aspects of both pinnae. Histologic examination revealed severe pyogranulomatous dermatitis with intracellular Ziehl-Neelsen-positive bacilli that were immunoreactive by immunohistochemistry using a polyclonal primary antibody that recognizes tuberculous and nontuberculous Mycobacterium species. DNA extracted from formalin-fixed, paraffin-embedded skin sections was tested by a Mycobacterium genus-specific nested PCR assay targeting the 16S rRNA gene. BLAST sequence analysis of 214-bp and 178-bp amplicons showed 99.5% identity with members of the MTBC; however, the agent could not be identified at the species level. Although CLG has been associated traditionally with nontuberculous mycobacterial infections, the role of Mycobacterium spp. within the MTBC as a cause of this condition, and the role of dogs with CLG as possible sources of MTBC to other animals and humans, should not be disregarded given its zoonotic potential.

Experimental acute Clostridium perfringens type D enterotoxemia in sheep is not characterized by specific renal lesions

Type D enterotoxemia, caused by Clostridium perfringens epsilon toxin (ETX), is one of the most economically important clostridial diseases of sheep. Acute type D enterotoxemia is characterized by well-documented lesions in the nervous, cardiocirculatory, and pulmonary systems. However, discrepancies and confusion exist as to whether renal lesions are part of the spectrum of lesions of this condition, which is controversial considering that for many decades it has been colloquially referred to as "pulpy kidney disease." Here, the authors assess renal changes in an experimental model of acute type D enterotoxemia in sheep and evaluate the possible role of ETX in their genesis. Four groups of 6 sheep each were intraduodenally inoculated with either a wild-type virulent C. perfringens type D strain, an etx knockout mutant unable to produce ETX, the etx mutant strain complemented with the wild-type etx gene that regains the ETX toxin production, or sterile culture medium (control group). All sheep were autopsied less than 24 hours after inoculation; none of them developed gross lesions in the kidneys. Ten predefined histologic renal changes were scored in each sheep. The proportion of sheep with microscopic changes and their severity scores did not differ significantly between groups. Mild intratubular medullary hemorrhage was observed in only 2 of the 12 sheep inoculated with the wild-type or etx-complemented bacterial strains, but not in the 12 sheep of the other 2 groups. The authors conclude that no specific gross or histologic renal lesions are observed in sheep with experimental acute type D enterotoxemia.

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

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

Pathologic and Immunohistochemical Evidence of Possible Francisellaceae among Aborted Ovine Fetuses, Uruguay

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.

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

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

A holstein heifer infected with Neospora caninum NcUru3 congenitally transmits this strain to a viable offspring although infection does not protect her from aborting by a different N. caninum genotype in the subsequent gestation

Neospora caninum is a leading cause of bovine abortion worldwide. Although the genetic diversity of this apicomplexan parasite has long been recognized, there is little information on whether infection with different genotypes results in different clinical outcomes or whether infection by a given genotype impairs protective immunity against abortion induced by different genotypes. Here, we provide evidence supporting that natural subclinical infection with isolate NcUru3 of N. caninum in a pregnant heifer did not provide protection against abortion caused by a different N. caninum genotype in the subsequent gestation. A Holstein heifer delivered a healthy calf congenitally infected with N. caninum. Specific anti-N. caninum IgG was detected by indirect ELISA in sera obtained from the dam at calving and the calf before ingestion of colostrum, indicating in utero exposure to the parasite in the latter. A N. caninum strain named NcUru3 was isolated and characterized by multilocus microsatellite typing from the brain of this neonate euthanized at 9 days of age. Sixty days after calving, the cow got pregnant, although she aborted spontaneously at ~6 months of gestation. Pathologic examination of the aborted fetus and placenta revealed typical lesions of neosporosis, including encephalitis, myocarditis, hepatitis, myositis, and placentitis. Neospora caninum DNA was amplified from the fetal brain, heart, kidney, and placenta, and multilocus microsatellite typing revealed a genotype that differed from isolate NcUru3 at the level of microsatellite marker 6A (MS6A). Serum obtained from the dam at the time of abortion had IgG that cross-recognized isolate NcUru3, as demonstrated by immunoblotting, indicating that the humoral immune response did not prevent the other genotype from infecting the fetus and inducing fetoplacental lesions and abortion. This is the first description of one same dam transmitting two N. caninum genotypes to her offspring in subsequent gestations.

Yellow Lamb Disease (Clostridium perfringens Type A Enterotoxemia of Sheep): A Review

Simple Summary

Yellow lamb disease is a poorly researched and understood condition that seems to affect young sheep. The disease is characterized by hemolysis and is thought to be caused by alpha toxin-producing Clostridium perfringens type A, although a definitive association with this microorganism has not been confirmed. This is due, in part, to the ubiquitous nature of C. perfringens type A, which is naturally present in the intestine of healthy sheep, a fact that complicates the diagnosis. In this review, we summarize the available information on the etiology, clinical signs, lesions, diagnosis, prevention and prophylaxis of yellow lamb disease.

Abstract

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.

Diagnostic Investigation of 100 Cases of Abortion in Sheep in Uruguay: 2015–2021

The aim of this work was to identify causes of abortion through laboratory investigations in sheep flocks in Uruguay. One hundred cases of abortion, comprising 58 fetuses, 36 fetuses with their placentas, and 6 placentas were investigated in 2015–2021. Cases were subjected to gross and microscopic pathologic examinations, and microbiological and serological testing for the identification of causes of abortion, including protozoal, bacterial, and viral pathogens. An etiologic diagnosis was determined in 46 (46%) cases, including 33 (33%) cases caused by infectious pathogens, as determined by the detection of a pathogen along with the identification of fetoplacental lesions attributable to the detected pathogen. Twenty-seven cases (27%) were caused by Toxoplasma gondii, 5 (5%) by Campylobacter fetus subspecies fetus, and 1 (1%) by an unidentified species of Campylobacter. Fourteen cases (14%) had inflammatory and/or necrotizing fetoplacental lesions compatible with an infectious etiology. Although the cause for these lesions was not clearly identified, T. gondii was detected in 4 of these cases, opportunistic bacteria (Bacillus licheniformis, Streptococcus sp.) were isolated in 2 cases, and bovine viral diarrhea virus 1 subtype i (BVDV-1i) was detected in another. Campylobacter jejuni was identified in 1 (1%) severely autolyzed, mummified fetus. BVDV-2b was identified incidentally in one fetus with an etiologic diagnosis of toxoplasmosis. Microscopic agglutination test revealed antibodies against ≥1 Leptospira serovars in 15/63 (23.8%) fetuses; however, Leptospira was not identified by a combination of qPCR, culture, fluorescent antibody testing nor immunohistochemistry. Neospora caninum, Chlamydia abortus, Chlamydia pecorum, Coxiella burnetii and border disease virus were not detected in any of the analyzed cases. Death was attributed to dystocia in 13 (13%) fetuses delivered by 8 sheep, mostly from one highly prolific flock. Congenital malformations including inferior prognathism, a focal hepatic cyst, and enterohepatic agenesis were identified in one fetus each, the latter being the only one considered incompatible with postnatal life. Toxoplasmosis, campylobacteriosis and dystocia were the main identified causes of fetal losses. Despite the relatively low overall success rate in establishing an etiologic diagnosis, a systematic laboratory workup in cases of abortion is of value to identify their causes and enables zoonotic pathogens surveillance.

Fatal Toxoplasma gondii myocarditis in an urban pet dog

A 70-day-old Boxer dog from a household in Montevideo, Uruguay, died after presenting neurologic, respiratory, and gastrointestinal signs for 6 days. Autopsy findings included lymphadenomegaly, ascites and hepatomegaly. Histopathology revealed severe widespread lymphohistiocytic and plasmacytic myocarditis with cardiomyocyte necrosis, mineralization and numerous intrasarcoplasmic protozoa immunoreactive with anti-Toxoplasma gondii antisera on immunohistochemistry. The protozoa were ultrastructurally confirmed as T. gondii by transmission electron microscopy. Other lesions included diffuse centrilobular hepatocellular necrosis, multifocal lymphohistiocytic portal hepatitis and interstitial nephritis. Other causes of myocarditis, including Neospora caninum, Trypanosoma cruzi, Sarcocystis neurona, canine distemper virus, and canine parvovirus were ruled out by immunohistochemistry. Toxoplasma gondii infections in dogs are usually subclinical; however, clinical disease with fatal outcome can occur. To our knowledge, this is the first report of fatal toxoplasmosis in a dog in Uruguay. This case raises awareness for dogs as sentinels and possible sources of human toxoplasmosis in urban settings in Uruguay.

Molecular characterization of multidrug-resistant Escherichia coli of the phylogroups A and C in dairy calves with meningitis and septicemia

Escherichia coli is an important cause of septicemia (SEPEC) and neonatal meningitis (NMEC) in dairy calves. However, the diversity of virulence profiles, phylogroups, antimicrobial resistance patterns, carriage of integron structures, and fluoroquinolone (FQ) resistance mechanisms have not been fully investigated. Also, there is a paucity of knowledge about the virulence profiles and frequency of potential SEPEC in feces from calves with or without diarrhea. This study aimed to characterize the virulence potential, phylogroups, antimicrobial susceptibility, integron content, and FQ-resistance mechanisms in Escherichia coli isolated from calves with meningitis and septicemia. Additionally, the virulence genes (VGs) and profiles of E. coli isolated from diarrheic and non-diarrheic calves were compared between them and together with NMEC and SEPEC in order to identify shared profiles. Tissue and fluid samples from eight dairy calves with septicemia, four of which had concurrent meningitis, were processed for bacteriology and histopathology. Typing of VGs was assessed in 166 isolates from diverse samples of each calf. Selected isolates were evaluated for antimicrobial susceptibility by the disk diffusion test. Phylogroups, integron gene cassettes cartography, and FQ-resistance determinants were analyzed by PCR, sequencing, and bioinformatic tools. Furthermore, 109 fecal samples and 700 fecal isolates from dairy calves with or without diarrhea were evaluated to detect 19 VGs by uniplex PCR. Highly diverse VG profiles were characterized among NMEC and SEPEC isolates, but iucD was the predominant virulence marker. Histologic lesions in all calves supported their pathogenicity. Selected isolates mainly belonged to phylogroups A and C and showed multidrug resistance. Classic (dfrA17 and arr3-dfrA27) and complex (dfrA17-aadA5::ISCR1::bla_CTX-M-2) class 1 integrons were identified. Target-site mutations in GyrA (S83L and D87N) and ParC (S80I) encoding genes were associated with FQ resistance. The VGs detected more frequently in fecal samples included f17G (50%), papC (30%), iucD (20%), clpG (19%), eae (16%), and afaE-8 (13%). Fecal isolates displaying the profiles of f17 or potential SEPEC were found in 25% of calves with and without diarrhea. The frequency of E. coli VGs and profiles did not differ between both groups (p > 0.05) and were identical or similar to those found in NMEC and SEPEC. Overall, multidrug-resistant E. coli isolates with diverse VG profiles and belonging to phylogroups A and C can be implicated in natural cases of meningitis and septicemia. Their resistance phenotypes can be partially explained by class 1 integron gene cassettes and target-site mutations in gyrA and parC. These results highlight the value of antimicrobial resistance surveillance in pathogenic bacteria isolated from food-producing animals. Besides, calves frequently shed potential SEPEC in their feces as commensals ("Trojan horse"). Thus, these bacteria may be disseminated in the farm environment, causing septicemia and meningitis under predisposing factors.

Placentitis and abortion caused by a multidrug resistant strain of Campylobacter fetus subspecies fetus in a sheep in Uruguay

Campylobacter fetusfetus (Cff) is a major infectious cause of abortion in sheep worldwide, and an opportunistic human pathogen. Information on Cff as an ovine abortifacient in South America is limited. We describe a case of abortion caused by a multidrug resistant strain of Cff in a sheep in Uruguay. In August 2017, 3/57 pregnant ewes (5.3%) aborted whithin one week. Histopathologic examination of the placenta of an aborted ewe revealed severe neutrophilic and fibrinonecrotizing placentitis with vasculitis and thrombosis of the chorionic arterioles. Cff was isolated on microaerobic culture in Skirrow agar, and further confirmed by 16S rDNA PCR amplification and sequencing, and endpoint and real time PCR assays. Antimicrobial sensitivity testing revealed resistance to tetracyclines, nalidixic acid, telithromycin and clindamycin. Other abortifacients were not detected. Further studies are necessary to determine the geographic distribution, ecology, epidemiology, economic impact, and antimicrobial resistance of Cff in sheep flocks in Uruguay.

Coxiella burnetii abortion in a dairy farm selling artisanal cheese directly to consumers and review of Q fever as a bovine abortifacient in South America and a human milk-borne disease

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.

Generalized dermatophytosis caused by Trichophyton equinum in 8 juvenile black bears in California

From 2014-2019, 8 juvenile black bears (Ursus americanus) from different geographic regions were presented to the California Department of Fish and Wildlife because of emaciation, alopecia, and exfoliative dermatitis that resulted in death or euthanasia. Autopsy and histopathology revealed that all 8 bears had generalized hyperkeratotic dermatitis, folliculitis, and furunculosis. Skin structures were heavily colonized by fungal hyphae and arthrospores; fungal cultures of skin from 7 bears yielded Trichophyton equinum, a zoophilic dermatophyte reported only rarely in non-equid species. Additional skin conditions included mites (5), ticks (2), and coagulase-negative Staphylococcus sp. infections (2). No other causes of morbidity or mortality were identified. Molecular comparisons performed at the University of Texas Fungal Reference Laboratory determined that all isolates produced identical banding patterns, potentially representing a clonal population. Dermatophytosis is commonly localized and limited to the stratum corneum of the epidermis and hair follicles. Generalized disease with dermal involvement is rare in immunocompetent individuals; illness, malnutrition, age, or immunosuppression may increase susceptibility. Underlying causes for the severe disease impact in these bears were not evident after physical or postmortem examination. The mechanism by which bears from different geographic locations had severe, T. equinum-associated dermatophytosis from a potentially clonal dermatophyte could not be explained and warrants further investigation.

Serological Evidence of Human Infection with Coxiella burnetii after Occupational Exposure to Aborting Cattle

Cattle are broadly deemed a source of Coxiella burnetii; however, evidence reinforcing their role in human infection is scarce. Most published human Q fever outbreaks relate to exposure to small ruminants, notably goats. Anti-phase II C. burnetii IgG and IgM were measured by indirect fluorescent antibody tests in 27 farm and veterinary diagnostic laboratory workers to ascertain whether occupational exposure to cattle aborting due to C. burnetii was the probable source of exposure. Four serological profiles were identified on the basis of anti-phase II IgG and IgM titres. Profile 1, characterised by high IgM levels and concurrent, lower IgG titres (3/27; 11.1%); Profile 2, with both isotypes with IgG titres higher than IgM (2/27; 7.4%); Profile 3 with only IgG phase II (5/27; 18.5%); and Profile 4, in which neither IgM nor IgG were detected (17/27; 63.0%). Profiles 1 and 2 are suggestive of recent C. burnetii exposure, most likely 2.5-4.5 months before testing and, hence, during the window of exposure to the bovine abortions. Profile 3 suggested C. burnetii exposure that most likely predated the window of exposure to aborting cattle, while Profile 4 represented seronegative individuals and, hence, likely uninfected. This study formally linked human Q fever to exposure to C. burnetii infected cattle as a specific occupational hazard for farm and laboratory workers handling bovine aborted material.

[Neurotropic bovine astrovirus-associated encephalitis: An underdiagnosed disease in South America?]

We describe a case of neurotropic bovine astrovirus-associated encephalitis in a Jersey dairy cow from the department of San José, Uruguay. This represents the second case of this condition reported in the Southern Hemisphere. The cow was the only one affected in a herd of 70 cows, showing neurological signs with a 2-day clinical course, before dying spontaneously. Histopathological examination revealed lymphocytic, histiocytic, and plasmacytic meningoencephalitis with neuronal necrosis, without detectable inclusion bodies. Other infectious agents, including Rabies virus(Lyssavirus), Bovine alphaherpesvirus-1 and Bovine alphaherpesvirus-5(Varicellovirus), Bovine viral diarrhea virus(Pestivirus), West Nile virus(Flavivirus), Listeria monocytogenes, Histophilus somni and other bacteria, were not detected in the brain. We propose that given the recent discovery of neurotropic astroviruses in various mammalian species, including humans, cases of astrovirus encephalitis may have gone undetected in South America. We briefly discuss the differential pathologic diagnosis of infectious bovine encephalitis.

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

Neonatal calf diarrhea (NCD) and mortality cause significant losses to the dairy industry. The preweaning dairy calf mortality risk in Uruguay is high (15.2%); however, causes for these losses are largely unknown. This study aimed to assess whether various pathogens were associated with NCD and death in Uruguayan dairy calves and whether these infections, diarrhea, or deaths were associated with the failure of transfer of passive immunity (FTPI). Contemporary diarrheic (n = 264,) and non-diarrheic (n = 271) 1- to 30-day-old calves from 27 farms were sampled. Feces were analyzed by antigen-capture ELISA for Cryptosporidium spp., rotavirus, bovine coronavirus, and Escherichia coli F5+, RT-PCR for bovine astrovirus (BoAstV), and bacterial cultures for Salmonella enterica. Blood/serum was analyzed by RT-PCR or antigen-capture ELISA for bovine viral diarrhea virus (BVDV). Serum of ≤ 8-day-old calves (n = 95) was assessed by refractometry to determine the concention of serum total proteins (STP) as an indicator of FTPI. Whether the sampled calves died before weaning was recorded. At least one pathogen was detected in 65.4% of the calves, and this percentage was significantly higher in diarrheic (83.7%) versus non-diarrheic (47.6%) calves. Unlike the other pathogens, Cryptosporidium spp. and rotavirus were associated with NCD. Diarrheic calves, calves infected with any of the pathogens, and calves infected with rotavirus had significantly lower concentrations of STP. Diarrheic calves had higher chances of dying before weaning than non-diarrheic calves. Diarrheic calves infected with S. enterica were at increased risk of mortality. Controlling NCD, salmonellosis, cryptosporidiosis, and rotavirus infections, and improving colostrum management practices would help to reduce calf morbi-mortality in dairy farms in Uruguay.

Detection, risk factors and molecular diversity of norovirus GIII in cattle in Uruguay

Uruguay is a leading exporter of bovine meat and dairy products, and cattle production is one of the principal economic backbones in this country. A main clinical problem faced by livestock farmers is neonatal calf diarrhea (NCD); however, causes of NCD have not been extensively studied in Uruguay. Bovine norovirus (BoNoV) has been proposed as one of the possible etiologies of NCD as experimentally infected calves developed diarrhea and enteropathy, although limited information is available from field surveys. The aims of this study were to determine the frequency of infection, to investigate possible risk factors, and to determine the molecular diversity of BoNoV in Uruguay. A total of 761 samples of feces or intestinal contents from dairy and beef calves were analyzed through RT-qPCR. The overall frequency of detection of BoNoV was 66.1% with higher frequency in dairy (70.5%) than beef (15.9%) calves (p < 0.01). BoNoV was detected similarly in diarrheic (78.8%) and non-diarrheic (76.2%) dairy calves (p = 0.50). Calves ≤2 weeks of age (84%) were infected more often than older (62.7%) calves (p < 0.01). Phylogenetic analysis confirmed the presence of GIII.1 and GIII.2 genotypes. In addition, we reported the circulation of recombinant strains and the detection of a strain with the recently described novel VP1 genotype. This study represents the first report describing the circulation, the associated risk factors, and the molecular diversity of BoNoV in Uruguay.

Cardiopulmonary Lesions in Sheep Produced by Experimental Acute Clostridium Perfringens Type D Enterotoxemia

Enterotoxemia caused by Clostridium perfringens type D is one of the most prevalent clostridial diseases of sheep. The lesions of the acute form of this disease, particularly the cerebral lesions, are well characterized; however, detailed descriptions of the cardiac and pulmonary lesions are lacking. Here we describe cardiopulmonary lesions in experimental acute type D enterotoxemia in sheep and determine the role of epsilon toxin (ETX) in the development of these lesions. Four groups of 6 sheep were intraduodenally inoculated with either a wild-type C. perfringens type D strain; its etx knockout mutant, which is unable to produce ETX; the etx mutant complemented with the wild-type etx gene, which regains the ETX toxigenic ability; or sterile culture medium as a control. All sheep were subjected to postmortem examination within 24 hours of inoculation. Lesion scores were compared between groups for pulmonary edema; hydrothorax; ascites; hydropericardium; endocardial, myocardial and epicardial hemorrhages; microscopic lesions of acute myocardial degeneration and necrosis; and myocardial, endocardial, and epicardial edema, hemorrhage, and inflammation. Only sheep inoculated with the wild-type and complemented ETX-toxigenic bacterial strains developed cardiopulmonary lesions, which were present in varying degrees of severity and proportions. These lesions were not present in sheep inoculated with the etx mutant or in the negative control. We conclude that severe acute cardiopulmonary lesions in sheep with experimental enterotoxemia are associated with the capacity of the strains to produce ETX. These changes are likely contributors to the clinical signs and even death of affected animals.

Baccharis coridifolia poisoning in livestock in Uruguay

Baccharis coridifolia is one of the most common poisonous plants affecting livestock in Uruguay. Poisoning occurs when animals raised in areas free of B. coridifolia are transported to pastures containing the plant. Young stock become spontaneously averted to it after ingesting non-toxic amounts of the plant. As B. coridifolia is widespread in the country, farmers selling livestock report when animals have been raised in areas with the plant, meaning that they are naturally averted and will not ingest it if introduced in B. coridifolia-containing paddocks. Of 2456 farmers from 18 departments of Uruguay selling cattle through online auctions between June 2019 and May 2020, 78% mentioned that the animals they were selling were raised in grasslands containing B. coridifolia. However, only 35.8% of the farmers from three departments of Eastern Uruguay mentioned that their cattle were raised in grasslands with B. coridifolia. Herds from these departments presented 16.7 times (95% CI: 13.1-21.3; p < 0.001) more risk of not being naturally averted to B. coridifolia ingestion than the herds of the other 15 departments of the country. In this paper we review all outbreaks of B. coridifolia poisoning reported in livestock in Uruguay from 1911 to present. We also describe three outbreaks of poisoning, one in cattle and two in sheep that were poisoned in the same farms in which the animals were raised. Intoxication occurred when the animals raised indoors and/or in cultivated pastures without B. coridifolia were introduced into grasslands of the same farms containing B. coridifolia. Typical gastrointestinal lesions were observed in pathological examinations. Furthermore, two of three necropsied heifers showed severe acute nephrosis, which had not been reported previously in this poisoning.

Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination

Cryptosporidium parvum, a major cause of diarrhea in calves, is of concern given its zoonotic potential. Numerous outbreaks of human cryptosporidiosis caused by C. parvum genetic subtypes are reported yearly worldwide, with livestock or water being frequently identified sources of infection. Although cryptosporidiosis has been reported from human patients in Uruguay, particularly children, epidemiologic information is scant and the role of cattle as reservoirs of zoonotic subtypes of C. parvum has not been explored. In this study, we aimed to (a)-identify C. parvum subtypes infecting dairy calves in Uruguay (including potentially zoonotic subtypes), (b)-assess their association with calf diarrhea, (c)-evaluate their spatial clustering, and (d)-assess the distance of infected calves to surface watercourses draining the farmlands and determine whether these watercourses flow into public water treatment plants. Feces of 255 calves that had tested positive for Cryptosporidium spp. by antigen ELISA were selected. Samples had been collected from 29 dairy farms in seven Uruguayan departments where dairy farming is concentrated and represented 170 diarrheic and 85 non-diarrheic calves. Selected samples were processed by nested PCRs targeting the 18S rRNA and gp60 genes followed by sequencing to identify C. parvum subtypes. Of seven C. parvum subtypes detected in 166 calves, five (identified in 143 calves on 28/29 farms) had been identified in humans elsewhere and have zoonotic potential. Subtype IIaA15G2R1 was the most frequent (53.6%; 89/166), followed by IIaA20G1R1 (24.1%; 40/166), IIaA22G1R1 (11.4%; 19/166), IIaA23G1R1 (3.6%; 6/166), IIaA17G2R1 (3%; 5/166), IIaA21G1R1 (2.4%; 4/166), and IIaA16G1R1 (1.8%; 3/166). There were no significant differences in the proportions of diarrheic and non-diarrheic calves infected with any of the C. parvum subtypes. Two spatial clusters were detected, one of which overlapped with Uruguay's capital city and its main water treatment plant (Aguas Corrientes), harvesting surface water to supply ~1,700,000 people. Infected calves on all farms were within 20–900 m of a natural surface watercourse draining the farmland, 10 of which flowed into six water treatment plants located 9–108 km downstream. Four watercourses flowed downstream into Aguas Corrientes. Calves are reservoirs of zoonotic C. parvum subtypes in Uruguay and pose a public health risk.

A survey of management practices that influence calf welfare and an estimation of the annual calf mortality risk in pastured dairy herds in Uruguay

Despite the importance of dairy farming in Uruguay, little information on dairy systems in this country is available in the scientific literature, and management practices that influence calf welfare at the herd level have not been explored. The aims of this study were to (1) describe the prepartum and calf-rearing systems, as well as the management practices that may influence calf welfare in pastured dairy herds in Uruguay, (2) estimate the annual calf mortality risk from birth to weaning, and (3) identify the primary clinical disease syndromes shown by the calves before death. A survey comprising a farm visit and a questionnaire was conducted on 225 randomly selected dairies with >30 milking cows, in 3 strata (31-99, 100-299, and ≥300 milking cows) of 6 Uruguayan departments where dairies are concentrated. Retrospective information from July 2013 to June 2014 was collected. A descriptive analysis was performed and results were inferred into the national dairy cattle population. Several management practices that could contribute to poor calf welfare were identified in a large proportion of farms. The annual calf mortality risk (calves that died between birth and weaning/calves born death or alive × 100, n = 149 farms) was 15.2%. Age at weaning averaged 75 d. Farmers reported that the most common clinical syndromes were diarrhea and respiratory disease in 85.2% and 47.5% of the farms, respectively. There was no continuous veterinary advice in 61.3% of the farms, 20.0% lacked data records, 38.5% had poor drainage in the prepartum area with waterlogging after rainfall, 52.1% monitored the prepartum area ≤2 times per day during the calving season, 65.1% did not perform navel antisepsis on newborns, 62.3% separated the calves from their dams at >24 h postpartum, 95.2% did not have a colostrum management program, 72.4% did not rotate the calf-rearing areas, 59.0% did not disinfect the calf feeders, 85.7% did not have staff dedicated exclusively to calf rearing, and 39.8% did not separate sick from healthy calves. The average volume of milk or milk replacer offered per calf was 4.5 L/day. Several of the identified management practices that affect calf welfare in the prepartum and calf-rearing periods could explain the high mortality risk. An effort should be made to conduct extension work focusing on the dissemination of good management practices to improve calf welfare and reduce calf mortality in Uruguayan dairy farms.

Phylogenetic Analyses of Rotavirus A from Cattle in Uruguay Reveal the Circulation of Common and Uncommon Genotypes and Suggest Interspecies Transmission

Uruguay is one of the main exporters of beef and dairy products, and cattle production is one of the main economic sectors in this country. Rotavirus A (RVA) is the main pathogen associated with neonatal calf diarrhea (NCD), a syndrome that leads to significant economic losses to the livestock industry. The aims of this study are to determine the frequency of RVA infections, and to analyze the genetic diversity of RVA strains in calves in Uruguay. A total of 833 samples from dairy and beef calves were analyzed through RT-qPCR and sequencing. RVA was detected in 57.0% of the samples. The frequency of detection was significantly higher in dairy (59.5%) than beef (28.4%) calves (p < 0.001), while it did not differ significantly among calves born in herds that were vaccinated (64.0%) or not vaccinated (66.7%) against NCD. The frequency of RVA detection and the viral load were significantly higher in samples from diarrheic (72.1%, 7.99 log₁₀ genome copies/mL of feces) than non-diarrheic (59.9%, 7.35 log₁₀ genome copies/mL of feces) calves (p < 0.005 and p = 0.007, respectively). The observed G-types (VP7) were G6 (77.6%), G10 (20.7%), and G24 (1.7%), while the P-types were P[5] (28.4%), P[11] (70.7%), and P[33] (0.9%). The G-type and P-type combinations were G6P[11] (40.4%), G6P[5] (38.6%), G10P[11] (19.3%), and the uncommon genotype G24P[33] (1.8%). VP6 and NSP1-5 genotyping were performed to better characterize some strains. The phylogenetic analyses suggested interspecies transmission, including transmission between animals and humans.

Virulence genes of Escherichia coli in diarrheic and healthy calves

Escherichia coli ETEC, EPEC, NTEC and STEC/EHEC pathotypes are often isolated from bovine feces. The objective of this study was to detect 21 E. coli virulence genes in feces from 252 dairy calves in Uruguay (149 with neonatal diarrhea - NCD - and 103 asymptomatic). Genes iucD, f17A, afa8E, papC, clpG and f17G(II) were the most prevalent (81.3%; 48.4%; 37.3%; 35.7%; 34.1%; 31.3%, respectively). Genes eae, stx1and stx2 were poorly represented; 13/252 animals harbored one or a combination of these genes. The prevalence of the cnf gene was 4.4%, while that of cdt-IV and cdt-III genes was 24.2% and 12.7% respectively. This study reports updated data about the virulence profiles of E. coli in dairy calves in Uruguay. A large number of adhesins and toxin genes were detected. Our results demonstrate that E. coli from bovine feces has diarrheagenic and extraintestinal profiles although other NCD risks factors may contribute to the disease outcome.

Causes of abortion in dairy cows in Uruguay

ABSTRACT: A case series study was conducted to determine the frequency of causes of abortion in dairy cattle in Uruguay. The sample size of 102 cases was composed of 53 fetuses, 35 fetuses with placentas, and 14 placentas without an associated fetus. All cases underwent gross and microscopic pathologic examinations as well as microbiological and serological testing. The etiology was determined in 54 (53%) of cases, 51 of which were caused by infectious agents. Within the observed 102 cases, 30 (29%) were caused by Neospora caninum, six (6%) by Coxiella burnetii and two (2%) by Campylobacter fetus subsp. venerealis. Bovine Parainfluenza-3 virus and Salmonella enterica serovar Newport caused one abortion each. Opportunistic bacteria (Escherichia coli, Streptococcus sp., Staphylococcus sp., Mannheimia sp., Trueperella pyogenes, and Providencia stuartii) were associated with 11 abortions. In two cases the fetal death was attributed to dystocia, and in one case the fetus had a congenital mesothelioma. Bovine viral diarrhea virus (BVDV) infection was identified in three fetuses; two of which were co-infected with and had typical lesions of N. caninum. No lesions were observed in the other fetus infected by BVDV. Leptospira interrogans was identified in one fetus without lesions. Despite the relatively low overall success rate in establishing an etiological diagnosis in cases of abortion in cattle, a systemic workup of bovine abortion is necessary to establish prevention and control strategies. This also facilitates monitoring and surveillance of reproductive diseases in dairy cattle, some of which represent a risk to public health.

Alimentary necrobacillosis in alpacas

Ulcers of the oral cavity, esophagus, and gastric compartments of South American camelids are uncommon. Multifocal-to-coalescing ulcers were identified in the oral cavity, esophagus, and/or gastric compartments of 5 alpacas submitted for postmortem examination. Fusobacterium necrophorum was isolated from the lesions in all alpacas, in combination with other aerobic and anaerobic bacteria. In 4 of these cases, F. necrophorum-associated lesions were considered secondary to neoplasia or other chronic debilitating conditions; in 1 case, the alimentary ulcers were considered the most significant autopsy finding. It is not known if this agent acted as a primary or opportunistic agent in mucosal membranes previously damaged by a traumatic event, chemical insult, immunodeficiency, or any other debilitating condition of the host.

Bovine Astrovirus Surveillance in Uruguay Reveals High Detection Rate of a Novel Mamastrovirus Species

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.

Isolation and molecular characterization of four novel Neospora caninum strains

Neospora caninum causes neosporosis, a leading cause of bovine abortion worldwide. Uruguay is a developing economy in South America that produces milk to feed seven times its population annually. Naturally, dairy production is paramount to the country's economy, and bovine reproductive failure impacts it profoundly. Recent studies demonstrated that the vast majority of infectious abortions in dairy cows are caused by N. caninum. To delve into the local situation and contextualize it within the international standing, we set out to characterize the Uruguayan N. caninum strains. For this, we isolated four distinct strains and determined by microsatellite typing that these represent three unique genetic lineages, distinct from those reported previously in the region or elsewhere. An unbiased analysis of the current worldwide genetic diversity of N. caninum strains known, whereby six typing clusters can be resolved, revealed that three of the four Uruguayan strains group closely with regional strains from Argentina and Brazil. The remaining strain groups in an unrelated genetic cluster, suggesting multiple origins of the local strains. Microsatellite typing of N. caninum DNA from fetuses opportunistically collected from local dairy farms correlated more often with one of the isolates. Overall, our results contribute to further understanding of genetic diversity among strains of N. caninum both regionally and worldwide.

Antibiotic resistance in Salmonella enterica isolated from dairy calves in Uruguay

Salmonella enterica is an important animal and human pathogen that can cause enteritis and septicaemia in calves. Generally, antibiotics are prescribed for the treatment of salmonellosis in dairy calves. Here, we report the isolation of antibiotic resistant S. enterica serotypes from calves, including multidrug-resistant isolates. A total of 544 faecal samples from live healthy and diarrheic dairy calves from 29 commercial dairy farms and organ samples from 19 deceased calves that succumbed to salmonellosis in 12 commercial dairy farms in Uruguay were processed for selective S. enterica culture. In total, 41 isolates were serotyped, and susceptibility to 14 antibiotics, from 9 classes of compounds, was evaluated by disk-diffusion test. The minimum inhibitory concentration (MIC) was determined by microdilution. Salmonella Typhimurium was the most frequent serotype, followed by S. Dublin and S. Anatum. Whether determined by diffusion assay or microdilution, resistance to tetracycline, streptomycin and ampicillin were the most frequently pattern found. Based on MIC, 5 isolates were resistant to at least one antibiotic, 21 were resistant to 2 antibiotics, and 14 were multidrug-resistant (resistant to at least one antibiotic in 3 different categories of antibiotics). Eleven different resistance patterns were found. Multidrug resistance in S. enterica is a concern for animal and public health not only because of its zoonotic potential but also due to the possibility of transfer resistance determinants to other bacterial genera. This represents the first report of the antibiotic resistance in S. enterica in dairy farms in Uruguay.

Bovine coronavirus in Uruguay: genetic diversity, risk factors and transboundary introductions from neighboring countries

Bovine coronavirus (BCoV) is a recognized cause of severe neonatal calf diarrhea, with a negative impact on animal welfare, leading to economic losses to the livestock industry. Cattle production is one of the most important economic sectors in Uruguay. The aim of this study was to determine the frequency of BCoV infections and their genetic diversity in Uruguayan calves and to describe the evolutionary history of the virus in South America. The overall detection rate of BCoV in Uruguay was 7.8% (64/824): 7.7% (60/782) in dairy cattle and 9.5% (4/42) in beef cattle. The detection rate of BCoV in samples from deceased and live calves was 10.0% (6/60) and 7.6% (58/763), respectively. Interestingly, there was a lower frequency of BCoV detection in calves born to vaccinated dams (3.3%, 8/240) than in calves born to unvaccinated dams (12.2%, 32/263) (OR: 4.02, 95%CI: 1.81–8.90; p = 0.00026). The frequency of BCoV detection was higher in colder months (11.8%, 44/373) than in warmer months (1.5%, 3/206) (OR: 9.05, 95%CI: 2.77–29.53, p = 0.000013). Uruguayan strains grouped together in two different lineages: one with Argentinean strains and the other with Brazilian strains. Both BCoV lineages were estimated to have entered Uruguay in 2013: one of them from Brazil (95%HPD interval: 2011–2014) and the other from Argentina (95%HPD interval: 2010–2014). The lineages differed by four amino acid changes, and both were divergent from the Mebus reference strain. Surveillance should be maintained to detect possible emerging strains that can clearly diverge at the antigenic level from vaccine strains.

Hypomagnesemia in dairy cattle in Uruguay

ABSTRACT: An outbreak of hypomagnesemia is reported in Holstein dairy cattle grazing lush oat (Avena sativa) pasture in Uruguay. Nine of 270 (3.3%) cows died in May-July (autumn-winter) 2017. These nine cows were from 2 to 9-years-old (1st-6th lactation), with 22 to 194 days of lactation and 15.8 to 31.4L of daily milk production. Two cows with acute sialorrhea, muscle spasms, lateral recumbency, weakness, opisthotonos, and coma, were euthanized and necropsied. No significant macroscopic or histological lesions were found. One untreated clinically-affected cow and eight out of 14 clinically healthy cows of the same group under similar management and production conditions had low serum levels of Mg (lower than 0.7mmol/L). Secondarily, both clinically affected cows and six out of 14 healthy cows had low serum Ca levels. The K/(Ca+Mg) ratio of two oat forages, corn silage, and ration was 5.10, 7.73, 2.45, and 0.85, respectively. A K/(Ca+Mg) ratio lower than 2.2 represents a risk for hypomagnesemia. The difference between the contribution-requirement of minerals in the diet was established and a daily deficiency of Mg (-0.36g/day), Na (-25.2g/day) and Ca (-9.27g/day) was found, while K (184.42g/day) and P (12.81g/day) were in excess. The diet was reformulated to correct the deficiencies and the disease was controlled by the daily administration of 80g of magnesium oxide, 80g of calcium carbonate and 30g sodium chloride per cow. It is concluded that hypomagnesemia is a cause of mortality in dairy cattle in Uruguay, and that the condition can be prevented by appropriate diet formulation.

Bovine abortion caused by Coxiella burnetii: report of a cluster of cases in Uruguay and review of the literature

A cluster of 4 bovine abortions caused by Coxiella burnetii occurred in a dairy herd in Uruguay during a 2-mo period. Case 1 consisted of a placenta from an aborted cow; cases 2-4 were fetuses and their placentas. Grossly, the placenta from one aborted cow had moderate, diffuse reddening of the cotyledons and loss of translucency of the intercotyledonary areas. No gross lesions were observed in the other 3 placentas. Microscopically, 2 of 4 placentas had fibrinonecrotizing placentitis with abundant intratrophoblastic gram-negative coccobacilli. C. burnetii was identified intralesionally by immunohistochemistry (IHC) in all 4 placentas, and by PCR and DNA sequencing in 3 placentas analyzed by these techniques. One fetus had mild neutrophilic alveolitis with multinucleate syncytial cells; no gross or microscopic lesions were observed in the other 2 fetuses examined. The lungs of the 3 fetuses were negative for C. burnetii by IHC. Tests performed to investigate other possible causes of abortions in the 4 cases were negative. C. burnetii causes Q fever in humans and coxiellosis in animals. Clusters of abortions in cattle by C. burnetii have not been reported previously, to our knowledge; this bacterium has been considered an opportunistic pathogen associated only with sporadic abortion in cattle. We present herein a cluster of 4 bovine abortions caused by C. burnetii in a dairy farm during a period of 2 mo and a review of the literature on C. burnetii infection in cattle.

Fatal Sarcocystis cruzi-induced eosinophilic myocarditis in a heifer in Uruguay

Sarcocystis spp. are causative agents of bovine eosinophilic myositis and/or myocarditis, which are chronic subclinical myopathies that are occasionally responsible for condemnation at slaughterhouses. Sarcocystis cruzi is a protozoan parasite of worldwide distribution transmitted by canids, most commonly associated with subclinical infection in cattle. Although S. cruzi infections can rarely lead to fatal systemic disease, fatal cardiac cases with confirmation of the etiologic diagnosis have not been reported, to our knowledge. We describe herein an unusual case of S. cruzi-induced fatal bovine eosinophilic myocarditis. A 22-mo-old, Holstein-Hereford heifer, in a group of 110 cattle on pasture, manifested growth retardation and died in February 2017. Autopsy revealed myriad yellow-green 1-3-mm coalescing foci, surrounded by fibrosis, affecting ~75% of the ventricular myocardium. Pulmonary edema, ascites, and hydrothorax were consistent with chronic congestive heart failure. Histology revealed severe eosinophilic, granulomatous, necrotizing myocarditis, with multinucleate giant cells, fibrosis, and mineralization. Numerous thin-walled protozoan cysts resembling Sarcocystis spp. were present in the necrotic foci and within the sarcoplasm of adjacent cardiomyocytes. PCR and sequencing of the 18S rRNA gene revealed 99.9-100% homology with S. cruzi. Sarcocystosis can be a rare cause of fatal myocarditis in cattle.

The First Case of Bovine Astrovirus-Associated Encephalitis in the Southern Hemisphere (Uruguay), Uncovers Evidence of Viral Introduction to the Americas From Europe

Astrovirus species members of the Mamastrovirus genus (family Astroviridae) have been increasingly recognized as neuroinvasive pathogens in various mammals, including humans, mink, cattle, sheep, and pigs. While cases of astrovirus-associated encephalitis have been reported in North America, Europe, and Asia, their presence has never been documented in the Southern hemisphere. This paper describes a case of astrovirus-associated encephalitis in cattle in Uruguay that broadens the geographic distribution and genetic diversity of neuroinvasive astroviruses and provides phylogeographic evidence of viral introduction to the Americas from Europe. A 22-month-old Holstein steer from a farm in Colonia Department, Uruguay developed progressive neurological signs over a 3-days period before dying. Histopathological examination of the brain and proximal cervical spinal cord revealed disseminated, moderate to severe lymphocytic, histiocytic, and plasmacytic poliomeningoencephalomyelitis with neuronal necrosis. A Mamastrovirus strain in the CH13/NeuroS1 clade, that we called bovine astrovirus (BoAstV)-Neuro-Uy, was identified by reverse transcriptase PCR followed by nearly complete genome sequencing. Additionally, BoAstV was detected intralesionally in the brain by chromogenic RNA in situ hybridization within neuronal perikarya, axons and dendrites. Phylogenetic analysis of BoAstV-Neuro-Uy revealed a close relationship to neurotropic BoAstVs within the Virginia/Human-Mink-Ovine clade, which contains a growing cadre of neuroinvasive astroviruses. Analyzing the complete coding region of neuroinvasive BoAstVs sequences available in GenBank, we estimated an evolutionary rate of 4.27 × 10^-4 (95% HPD 2.19–6.46 × 10^-4) nucleotide substitutions/site/year. Phylogeographic analysis suggests that the common viral ancestor circulated in Europe between 1794–1940, and was introduced in Uruguay between 1849–1967, to later spread to North America and Japan.

Outbreak of contagious ecthyma caused by Orf virus (Parapoxvirus ovis) in a vaccinated sheep flock in Uruguay

Orf virus (ORFV) causes contagious ecthyma (CE), a highly transmissible, zoonotic disease of small ruminants. CE most commonly affects lambs and unvaccinated sheep. This work reports epidemiologic, clinicopathologic, and virologic findings in a CE outbreak in a vaccinated sheep flock in Uruguay and failure to detect ORFV in a commercial vaccine.

Intrapericardial Encephalitozoon pogonae-associated arteritis with fatal hemopericardium in two juvenile central bearded dragons

Two male juvenile central bearded dragons ( Pogona vitticeps) were submitted for postmortem examination after dying at their respective homes. Dragon 1 had marked hemopericardium with restrictive epicarditis. The inner aspect of the distended pericardial sac was lined by a fibrinoheterophilic membrane. In addition, granulomas abutted the testes. Dragon 2 had acute hemopericardium and granulomatous arteritis of the great vessels exiting the heart. Histologically, both animals had granulomatous arteritis of the large arteries with intrahistiocytic gram-positive, slightly elongated, up to 2 μm long microorganisms that contained a vacuole. These microorganisms were also present in the paratesticular granulomas. On transmission electron microscopy, the microorganisms were identified as microsporidians given the presence of exospore, endospore, vacuole, nucleus, and a filament with 4-6 coils. The microsporidia were identified as Encephalitozoon pogonae based on sequencing of the internal transcribed spacer 1 of the ribosomal RNA genes. Microsporidia are agents of disease in bearded dragons. Intrapericardial arteritis of large arteries with hemopericardium or restrictive epicarditis is a fatal manifestation of this infection.

Acute lead arsenate poisoning in beef cattle in Uruguay

We describe and illustrate lesions in an outbreak of lead arsenate poisoning in beef cattle that ingested pesticide residues stored in an abandoned building of a former orange orchard. Of 70 exposed cattle, 14 had diarrhea, paresis, ataxia, recumbency, and/or seizures. Ten of the affected animals died after a clinical course of 12-18 h. Pathologic findings in 3 steers included extensive necrohemorrhagic, ulcerative rumenitis, omasitis, and abomasitis; lymphocytolysis in lymphoid organs; and nephrosis. Hepatic arsenic and lead levels in cases 1-3 were 20, 24, and 31 ppm, and 8.3, 25, and 9.4 ppm, respectively. Lesions in the forestomachs and lymphoid tissues have been rarely reported in cases of lead arsenate poisoning. In southern South America, these lesions are indistinguishable from those produced by Baccharis coridifolia, a toxic plant that contains macrocyclic trichothecenes, thus these conditions should be considered in the differential diagnosis of necrotizing lesions in alimentary and lymphoid organs.

Diagnosis of Bovine Genital Campylobacteriosis in South America

Bovine genital campylobacteriosis (BGC) is a venereal infectious disease that affects reproduction. It is caused by the Gram-negative bacillus Campylobacter fetus subspecies venerealis (Cfv), which may include the biotype intermedius. The bull is a lifelong asymptomatic carrier and transmitter of the disease. In females Cfv may cause infertility and sporadic abortion. The objective of this study is to review and discuss methods for the diagnosis of BGC, its prevalence and economic impact in South America. BGC is a worldwide distributed disease and can cause a pregnancy rate decrease of 15-25%. The farm prevalence of BGC in different regions of South American countries shows a variation between 2.3 and 100%. Discrepancies may depend on the differences on sanitary, management, and reproductive practices between farms and regions, but also on the interpretation of different diagnostic tests. Currently known laboratory tests include bacterial culture, direct immunofluorescence, immunoenzymatic assays, vaginal mucus agglutination test, PCR-based methods, histology and immunohistochemistry, which are applied and interpreted in diagnostic laboratories at different scales. Epidemiologic data of BGC in South America should be interpreted with caution. High prevalence has been reported in some studies, although the low specificity of the diagnostic tests used could lead to an overestimation of the results.

Urocystitis and Ureteritis in Holstein Calves with Septicaemia Caused by Salmonella enterica Serotype Dublin

Salmonellosis is an enteric or multisystemic disease of global distribution that affects numerous animal species. Although Salmonella enterica has been associated with urinary tract lesions in man, information on urocystitis/ureteritis in cattle caused by salmonellae is lacking. This communication describes lesions of the inferior urinary tract in four Holstein calves with septicaemia caused by S. enterica subsp. enterica serotype Dublin. Examination of the urinary bladder revealed either diffuse irregular thickening (three cases) or petechiation (one case) of the mucosa. On histopathological examination, urocystitis with submucosal histiocytic, lymphocytic and plasmacytic infiltration and neutrophil transmigration through the urothelium was noted in all cases. In one case, a fibrinosuppurative ureteritis was detected. Salmonella Dublin was identified by culture, 16S rDNA sequencing and serotyping and Salmonella antigen was detected intralesionally by immunohistochemistry. Other lesions, indicative of septicaemia included hepatitis, enteritis, pericarditis, splenitis, lymphadenitis and pneumonia. We conclude that S. Dublin can be uropathogenic in cattle with septicaemia.

Fetal Pathology in an Aborted Holstein Fetus Infected With Bovine Parainfluenza Virus-3 Genotype A

Bovine parainfluenza virus-3 (BPIV-3) is a recognized respiratory pathogen of cattle, and it has also been identified in aborted fetuses. However, little is known of this agent as a reproductive pathogen and detailed descriptions of fetal pathology on natural cases are lacking in the scientific literature. This article describes and illustrates lesions in a fetus spontaneously aborted by a first-calving Holstein heifer, naturally infected with BPIV-3 genotype A, broadening the current knowledge on fetal pathology by this virus. Fetal autopsy revealed diffusely reddened, rubbery and unexpanded lungs. Histologically, there was necrotizing bronchiolitis/alveolitis with intraluminal fibrin exudate and syncytial cells in the bronchiolar/alveolar spaces, and non-suppurative peribronchiolitis and perivascular interstitial pneumonia. In the small intestine there was multifocal necrotizing cryptitis and occasional necrotic syncytial enterocytes. Intralesional and extralesional BPIV-3 antigen was detected by immunohistochemistry in the lung and small intestine, and BPIV-3a was identified in fetal tissues by RT-PCR and sequencing.

Isolation of pathogenic Leptospira strains from naturally infected cattle in Uruguay reveals high serovar diversity, and uncovers a relevant risk for human leptospirosis

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.

Several species of the genus Leptospira cause leptospirosis, a disease that is transmitted from animals to humans (zoonosis). Leptospirosis is the most extended zoonosis worldwide, with over a million human cases each year. Leptospira spp. infect a broad range of wildlife and domestic animals, including cattle. In several South American countries beef and dairy exports rank among the most important national income sources, explaining why in Uruguay cattle outnumber human population by a factor of 4. Yet, we did not know which Leptospira species and serovariants (serovars) circulate among Uruguayan cattle. Current serologic diagnostic methods and whole killed-cell vaccination approaches, critically depend on using the proper serovars, which are hugely variable in Leptospira spp. from different regions of the world. Through a multidisciplinary consortium effort, we now report the isolation and typing of 40 strains of pathogenic Leptospira spp. An unexpectedly large variation in terms of species and serovars was found. These data are extremely important: 1- to improve diagnostics by updating the available reference antigen panels; 2- to evaluate the efficacy of novel vaccines; and, 3- to implement efficacious bovine vaccination as a means of reducing the incidence of bovine and human leptospirosis.