Neospora caninum in aborted bovine fetuses in Trakya Region, Turkey - histopathological, immunohistochemical and molecular detection

Background: Being the major cause of bovine abortion in the world, Neosporosis is considered to be a very important protozoal infection in dairy cattle. Vertical transplacental transmission is the major route of the infection causing either abortion or birth of calves with persistent infection. As the seropositivity in individual cows and in fetal serology only indicate exposure to the protozoa, the diagnosis of the infection has to be based on histopathology of aborted fetuses. Additional techniques such as immunohistochemistry (IHC) and PCR are required for the detection of the etiological agent. The purpose of the current study was to diagnose Neospora caninum infection in aborted bovine fetuses in Trakya Region of Turkey. For this purpose, serological, histopathological, IHC, and PCR methods were used. Materials, Methods & Results: The blood samples and the fetuses of 55 aborted dairy cattle from various farms located in 3 provinces of Trakya, Turkey constituted the material of the present study. The sera obtained from the blood samples were tested using a Neospora caninum Antibody Test Kit cELISA and anti-N. caninum antibodies were detected in the sera of the dams of the 8 aborted fetuses (8/55; 14.54%). Following the necropsy, samples from the brain, heart, liver, lung, kidney, spleen, and placenta of 55 fetuses were routinely processed for histopathological examination and evaluated under a light microscope. Nonsuppurative encephalitis (15/55; 27.27%), necrosis (5/55; 9%) and gliosis (1/55; 1.8%) in the brain, mild to severe nonsuppurative myocarditis and epicarditis (14/55; 25.45%), and portal to mid-zonal nonsuppurative hepatitis (13/55; 23.63%) were the relevant findings. PCR analysis was performed on fresh frozen fetal tissues. Nested PCR detected N. caninum DNA in the brain, heart, liver, lung, and kidney tissues of 6 fetuses (6/55; 10.9%). IHC was performed on the brain, heart, and liver tissues of all the fetuses using avidin-biotin-complex peroxidase method. Immunoreactivity was observed in the brain of 1 fetus (1/55; 1.8%). Discussion: In the present study, histopathological, immunohistochemical and PCR analyses were performed to detect N. caninum in 55 spontenously aborted bovine fetuses in Trakya Region, Turkey. Histopathologic hallmark of the study was nonsuppurative inflammation found mostly in the brain, heart and liver followed by kidneys and lungs. No protozoa was observed in the microscopic examination supporting the fact that definitive diagnosis of N. caninum infection requires ancillary techniques such as IHC and PCR. Nested PCR detected N. caninum DNA in the tissues of 6 fetuses (6/55; 10.9%). Brain was the most reliable organ for detection by PCR (6/6; 100%), compatible with the previous reports. IHC diagnosis revealed only 1.8% positivity in the present study which was remarkably lower than found in the previous studies. Even though histopathology in conjunction with IHC are accepted as the "gold standard" methods to detect N. caninum infection in aborted bovine fetuses, there are studies claiming that IHC is relatively insensitive in the diagnosis of neosporosis as parasite numbers can be low and thus, false negative results can be obtained. Other factors affecting the sensitivity of the technique are thoroughly discussed by many authors. Supportively, the findings of the current study showed that using both IHC and PCR as complementary techniques, increases the success of detection of N. caninum as recommended in previous studies. In conclusion, the present study demonstrated the first molecular diagnosis of Neospora caninum infection in bovine aborted fetuses in Trakya Region of Turkey which has a critical geographical location bordering Europe.

Infectious bovine abortions: observations from an organized dairy herd.

Abortions in dairy animals can be caused by several infectious agents. Identification of the actual causal agent(s) is important for formulating suitable control strategies. A 3-year (2016-2018) longitudinal study was conducted in a dairy farm following an abortion storm in the mid- to late gestations. The investigation focused on the seven major infectious abortifacient in cattle, viz. bovine alphaherpesvirus-1 (BoHV-1), bovine viral diarrhoea virus (BVDV), Neospora caninum, Brucella abortus, Coxiella burnetii, Leptospira Hardjo, and Listeria monocytogenes. High seroprevalence was observed for BVDV (79.4%), Leptospira (70.5%), BoHV-1 (53.5%), and Brucella (45.0%) at the beginning of the investigation (August 2016). The incidence proportion increased for BVDV, Leptospira, and Brucella in the following years of the investigation. A strong association of Brucella seropositivity with history of abortion (OR = 3.27) was recorded. Incidence of BoHV-1 reduced during the period of study coincident with systematic IBR inactivated marker vaccination of the herd. Sixty-four abortion cases were investigated for the identification of causative agent(s) by microbial culture, serological (ELISA), and molecular detection (PCR/ real-time PCR). Antibodies to BVDV, Brucella, BoHV-1, Leptospira, Neospora, and Coxiella were detected in 63, 61, 56, 35, 5, and 6 aborting cattle, respectively. Real-time PCR/PCR of clinical specimens detected DNA of Brucella, BoHV-1, Coxiella, Leptospira, and Listeria in 34, 13, 12, 9, and 4 abortion cases, respectively. BVDV and Neospora were not detected in any specimen samples. Brucella abortus isolated from the farm was determined as ST1 by multi-locus sequence typing (MLST). DNA of multiple agents were detected in 21 of the 64 cases (43.75%). Overall, the data suggests, Brucella was the major causative agent, although multiple causative agents circulated in the farm.

Improvement of Leptospira spp. diagnosis in aborted bovine fetuses by qPCR.

Leptospirosis is a disease with major economic impact on livestock industry. The objective of this work was to determine the presence of Leptospira spp. DNA by qPCR in bovine fetuses with presumptive diagnosis of leptospirosis as the cause of abortion. Leptospira spp. DNA was detected by qPCR in 11 out of 34 fetuses. These specimens (10/11) had histopathological findings in hepatic and/or renal tissues compatible with leptospirosis. qPCR detection rate (32.4 %) was higher compared with direct immuno-fluorescence antibody test (DFAT) (11.8 %). The concordance coefficient between both techniques was 0.44. qPCR is a rapid and sensitive technique for the diagnosis of leptospirosis and improved the detection rate in fetal tissues compared with DFAT. Implementation of molecular techniques may increase the accurate detection of leptospirosis as a cause of bovine abortion allowing the application of rapid therapeutic and prophylactics measures in order to reduce the impact of this zoonotic disease.

Spontaneous abortion in cattle after consumption of Hesperocyparis (Cupressus) macrocarpa (Hartw.) Bartel and Cupressus arizonica (Greene) needles in Uruguay.

An outbreak of cattle abortion associated with the consumption of Hesperocyparis (Cupressus) macrocarpa and Cupressus arizonica needles has been reported in Uruguay. Twenty-five of 125 pregnant heifers in late-term pregnancy aborted after being introduced into a paddock containing numerous H. macrocarpa, C. arizonica and Casuarina cunninghamiana trees. There were no significant macroscopic or histological findings in the two fetuses analyzed. Abortifacient labdane acids were detected in the needles of H. macrocarpa (1.68%, D.W.) and C. arizonica (0.36%, D.W.) but none were found in C. cunninghamiana.

Causes of abortion in dairy cows in Uruguay / Causas de aborto em bovinos de leite no Uruguai

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.(AU)

Uma série de casos foi estudada para determinar a frequência de causas do aborto em bovinos leiteiros no Uruguai. A amostra, de 102 casos, foi composta por 53 fetos, 35 fetos com placentas e 14 placentas sem feto associado. Todos os casos foram submetidos a exames patológicos macroscópicos e microscópicos, além de testes microbiológicos e sorológicos. A etiologia foi determinada em 54 (53%) dos casos, 51 dos quais foram causados por agentes infecciosos. Nos 102 casos observados, 30 (29%) foram causados por Neospora caninum, seis (6%) por Coxiella burnetii e dois (2%) por Campylobacter fetus subsp. venerealis. O vírus da Parainfluenza-3 e Salmonella enterica serovar Newport causaram um aborto cada. Bactérias oportunistas (Escherichia coli, Streptococcus sp., Staphylococcus sp., Mannheimia sp., Trueperella pyogenes e Providencia stuartii) foram associadas a 11 abortos. Em dois casos, a morte fetal foi atribuída a distocia e, em um caso, o feto apresentava mesotelioma congênito. A infecção pelo vírus da diarreia viral bovina (BVDV) foi identificada em três fetos; dois dos quais foram co-infectados e apresentavam lesões típicas de N. caninum. Não foram observadas lesões no outro feto infectado pelo BVDV. Leptospira interrogans foi identificada em um feto sem lesões. Apesar da relativamente baixa taxa de sucesso no diagnóstico etiológico nos casos de aborto em bovinos, é necessário o diagnóstico sistemático dos abortos para estabelecer estratégias de prevenção e controle. Isso também facilita o monitoramento e a vigilância de doenças reprodutivas em bovinos leiteiros, algumas das quais representam um risco para a saúde pública.(AU)

Causes of abortion in dairy cows in Uruguay / Causas de aborto em bovinos de leite no Uruguai

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.(AU)

Uma série de casos foi estudada para determinar a frequência de causas do aborto em bovinos leiteiros no Uruguai. A amostra, de 102 casos, foi composta por 53 fetos, 35 fetos com placentas e 14 placentas sem feto associado. Todos os casos foram submetidos a exames patológicos macroscópicos e microscópicos, além de testes microbiológicos e sorológicos. A etiologia foi determinada em 54 (53%) dos casos, 51 dos quais foram causados por agentes infecciosos. Nos 102 casos observados, 30 (29%) foram causados por Neospora caninum, seis (6%) por Coxiella burnetii e dois (2%) por Campylobacter fetus subsp. venerealis. O vírus da Parainfluenza-3 e Salmonella enterica serovar Newport causaram um aborto cada. Bactérias oportunistas (Escherichia coli, Streptococcus sp., Staphylococcus sp., Mannheimia sp., Trueperella pyogenes e Providencia stuartii) foram associadas a 11 abortos. Em dois casos, a morte fetal foi atribuída a distocia e, em um caso, o feto apresentava mesotelioma congênito. A infecção pelo vírus da diarreia viral bovina (BVDV) foi identificada em três fetos; dois dos quais foram co-infectados e apresentavam lesões típicas de N. caninum. Não foram observadas lesões no outro feto infectado pelo BVDV. Leptospira interrogans foi identificada em um feto sem lesões. Apesar da relativamente baixa taxa de sucesso no diagnóstico etiológico nos casos de aborto em bovinos, é necessário o diagnóstico sistemático dos abortos para estabelecer estratégias de prevenção e controle. Isso também facilita o monitoramento e a vigilância de doenças reprodutivas em bovinos leiteiros, algumas das quais representam um risco para a saúde pública.(AU)

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.

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.

Identification of Neospora caninumin aborted bovine fetuses of southern Chile

The aim of this study was to identify Neospora caninum in histologic sections of brain and optic nerve of aborted bovine fetuses. Sections of these tissues from 296 aborted bovine fetuses from Southern Chile, submitted between 2000 and 2010, to the Instituto de Patología Animal of the Universidad Austral de Chile were analyzed. Forty-four (14.9%) fetuses had microscopic lesions compatible with bovine neosporosis, including gliosis, necrosis, intralesional protozoan cysts and neuritis of optic nerves. N. caninum was identified by immunohistochemistry in brain sections of 27 cases (9.1%) with compatible lesions. Positive immunostaining was also found in the optic nerves of 13 cases (4.4%) with neuritis. N. caninum DNA was identified by PCR in brain sections in 31 cases (10.5%). In total, 36 cases (12.2%) were positive by either technique. Phylogenetic analysis of the ITS1 gene sequence of N. caninum revealed a high degree of conservation among different isolates. This is the first report of N. caninum-associated optic neuritis in cattle and also the first report of confirmed bovine abortion associated with this parasite in Chile.

Identification of Neospora caninumin aborted bovine fetuses of southern Chile

The aim of this study was to identify Neospora caninum in histologic sections of brain and optic nerve of aborted bovine fetuses. Sections of these tissues from 296 aborted bovine fetuses from Southern Chile, submitted between 2000 and 2010, to the Instituto de Patología Animal of the Universidad Austral de Chile were analyzed. Forty-four (14.9%) fetuses had microscopic lesions compatible with bovine neosporosis, including gliosis, necrosis, intralesional protozoan cysts and neuritis of optic nerves. N. caninum was identified by immunohistochemistry in brain sections of 27 cases (9.1%) with compatible lesions. Positive immunostaining was also found in the optic nerves of 13 cases (4.4%) with neuritis. N. caninum DNA was identified by PCR in brain sections in 31 cases (10.5%). In total, 36 cases (12.2%) were positive by either technique. Phylogenetic analysis of the ITS1 gene sequence of N. caninum revealed a high degree of conservation among different isolates. This is the first report of N. caninum-associated optic neuritis in cattle and also the first report of confirmed bovine abortion associated with this parasite in Chile.(AU)

Genome sequencing of two Bacillus anthracis strains: a virulent strain and a vaccinal strain

ABSTRACT Bacillus anthracis strain SPV842_15 was isolated from bovine fetus, while B. anthracis strain Brazilian vaccinal was recovered from a commercial vaccine. We report here the genome sequences of both strains. The SPV842_15 genome is composed of a single circular chromosome with a length of 5,228,664 base pairs, and comprises 5911 coding sequences. In turn, the Brazilian vaccinal genome remains in 201 contigs with 5733 coding sequences. Both genomes have an overall C + G content of 35.4%, and 11 genes encoding the ribosomal RNAs (rRNAs) 5S, 16S and 23S. Only the plasmid pX01 sequence, which carries genes for toxins synthesis, was detected and completely assembled for both strains. These plasmids have a length of 181,684 base pairs and a C + G content of 32.5%. These genomic data generate insights about vaccinal B. anthracis virulence.

Genome sequencing of two Bacillus anthracis strains: a virulent strain and a vaccinal strain

Bacillus anthracis strain SPV842_15 was isolated from bovine fetus, while B. anthracis strain Brazilian vaccinal was recovered from a commercial vaccine. We report here the genome sequences of both strains. The SPV842_15 genome is composed of a single circular chromosome with a length of 5,228,664 base pairs, and comprises 5911 coding sequences. In turn, the Brazilian vaccinal genome remains in 201 contigs with 5733 coding sequences. Both genomes have an overall C + G content of 35.4%, and 11 genes encoding the ribosomal RNAs (rRNAs) 5S, 16S and 23S. Only the plasmid pX01 sequence, which carries genes for toxins synthesis, was detected and completely assembled for both strains. These plasmids have a length of 181,684 base pairs and a C + G content of 32.5%. These genomic data generate insights about vaccinal B. anthracis virulence.(AU)

Genome sequencing of two Bacillus anthracis strains: a virulent strain and a vaccinal strain.

Bacillus anthracis strain SPV842_15 was isolated from bovine fetus, while B. anthracis strain Brazilian vaccinal was recovered from a commercial vaccine. We report here the genome sequences of both strains. The SPV842_15 genome is composed of a single circular chromosome with a length of 5,228,664 base pairs, and comprises 5911 coding sequences. In turn, the Brazilian vaccinal genome remains in 201 contigs with 5733 coding sequences. Both genomes have an overall C+G content of 35.4%, and 11 genes encoding the ribosomal RNAs (rRNAs) 5S, 16S and 23S. Only the plasmid pX01 sequence, which carries genes for toxins synthesis, was detected and completely assembled for both strains. These plasmids have a length of 181,684 base pairs and a C+G content of 32.5%. These genomic data generate insights about vaccinal B. anthracis virulence.

Can hierarchical modeling improve our understanding of bovine abortion due to Neospora caninum infection?

The purpose of this study was to use mixed logistic regression to evaluate the association between Neospora caninum serostatus and abortion, accounting for the effects of farms. The main objective was to explore the interpretation of this model and discuss the contribution of this analysis to our understanding of the disease's epidemiology. A mixed-effects logistic model using farms as a random effect and the serostatus for N. caninum, age of cattle and farm location as fixed effects was performed. The data from 1256 cows over 15 months of age from 60 farms were used, and the abortion information was obtained from farm records. A significant association between N. caninum serostatus and abortion was found (p<0.0001). Seropositive cows had 6.63 times greater odds of having a history of previous abortion (95% CI: 4.35-13.37). There was remarkable variability across farms in the probability of a cow having a history of an abortion. Including the effects of the farms in the regression, it was possible to estimate an intraclass correlation coefficient (ICC) of 16%. That means that 16% of the variation in abortion occurrence that was not explained by the fixed effects was due to farms. In practical terms, this variation means that while there are farms with several seropositive cows and no/few abortion cases, the opposite is also true, with a high number of abortions in farms with low/medium seroprevalence. The remaining variability (84%) was not explained by the effect of N. caninum, age, region, and the effect of farms, i.e., it is due to unknown factors that are causing abortions. The results of this study reinforce the importance of N. caninum as a cause of abortions and demonstrate the significant heterogeneity in the probability of a cow having a history of an abortion that cannot be explained completely by N. caninum serostatus, age or location. Including the hierarchical structure of the population along with correct interpretation of the model estimates helps us understand the effect of the farms, i.e., the probability of a cow abortion conditional to the farms, which also contributes to our understanding of the epidemiology of abortions caused by neosporosis. The use of hierarchical models and reporting the ICC should be encouraged.

Causas de aborto bovino diagnosticadas no Setor de Patologia Veterinária da UFRGS de 2003 a 2011 / Causes of bovine abortion diagnosed by the Sector of Veterinary Pathology of the Federal University of Rio Grande do Sul in the years 2003-2011

The main causes of abortion in cattle diagnosed from January 2003 to December 2011 are described. A total of 490 fetuses from several Brazilian states were evaluated. Specific causes of abortion were found in 46.7% of the cases,and protozoan abortions, especially by Neospora caninum, were detected in 33% (162/490). Bacterial abortions corresponded to 6.3 % (31/490), followed by fungal ones to 0.8% (4/490). In two aborted fetuses (0.4 %), a co-infection with two agents could be identified. Non-infectious diseases could be associated with 3% of the abortions and congenital malformations with 2.6%.

Descrevem-se as causas de aborto bovino diagnosticadas no Setor de Patologia Veterinária da Universidade Federal do Rio Grande do Sul no período de janeiro de 2003 a dezembro de 2011. Um total de 490 fetos bovinos foi analisado neste período. Causas específicas de aborto foram encontradas em 46,7% dos casos. Infecções por protozoários, em especial Neospora caninum acometeram 33% dos casos (162/490). Bactérias com 6,3% (31/490), seguidas por fungos com 0,8% (4/490) dos casos, foram causas adicionais de abortos. Em dois fetos (0,4%), coinfecções por dois agentes foram identificadas. Causas não-infecciosas foram observadas em 3% dos abortos e Malformações congênitas em 2,6%.

Causas de aborto bovino diagnosticadas no Setor de Patologia Veterinária da UFRGS de 2003 a 2011 / Causes of bovine abortion diagnosed by the Sector of Veterinary Pathology of the Federal University of Rio Grande do Sul in the years 2003-2011

The main causes of abortion in cattle diagnosed from January 2003 to December 2011 are described. A total of 490 fetuses from several Brazilian states were evaluated. Specific causes of abortion were found in 46.7% of the cases,and protozoan abortions, especially by Neospora caninum, were detected in 33% (162/490). Bacterial abortions corresponded to 6.3 % (31/490), followed by fungal ones to 0.8% (4/490). In two aborted fetuses (0.4 %), a co-infection with two agents could be identified. Non-infectious diseases could be associated with 3% of the abortions and congenital malformations with 2.6%.(AU)

Descrevem-se as causas de aborto bovino diagnosticadas no Setor de Patologia Veterinária da Universidade Federal do Rio Grande do Sul no período de janeiro de 2003 a dezembro de 2011. Um total de 490 fetos bovinos foi analisado neste período. Causas específicas de aborto foram encontradas em 46,7% dos casos. Infecções por protozoários, em especial Neospora caninum acometeram 33% dos casos (162/490). Bactérias com 6,3% (31/490), seguidas por fungos com 0,8% (4/490) dos casos, foram causas adicionais de abortos. Em dois fetos (0,4%), coinfecções por dois agentes foram identificadas. Causas não-infecciosas foram observadas em 3% dos abortos e Malformações congênitas em 2,6%.(AU)

Aproximación epidemiológica para medir y entender el aborto bovino / Epidemiologic approaches for measuring and understanding bovine abortion

El objetivo del presente artículo es ilustrar algunos métodos para medir la tasa de aborto en bovinos. Así mismo, se describirán algunas de las asociaciones que se han encontrado entre aspectos demográficos, características reproductivas y la subsecuente presentación de aborto. El método de las tablas de vida permite calcular el riesgo de pérdida fetal (aborto) en unos intervalos predefinidos (ej. días o meses) durante la gestación, y la proporción de vacas que abortan. Por otro lado, el método de la densidad de aborto permite calcular el riesgo de aborto en un período calendario definido (ej. por mes) como una medida del número de abortos durante los días en que la vaca estuvo a riesgo. Ambos métodos estandarizan la información y toman en cuenta el cambio en el número de vacas a riesgo de abortar ya que excluye aquellas que ya no lo están porque fueron vendidas, murieron, abortaron o parieron; por ello proveen un resultado más alto, pero también más real de lo que normalmente se calcula. Estas medidas y modelos estadísticos han sido utilizados para calcular la magnitud esperada de aborto en fincas lecheras (cuyo rango varía entre 8-19%) y también para identificar asociaciones entre factores demográficos o características reproductivas de la vaca y el subsecuente riesgo de aborto. Algunos de esos factores serán discutidos incluyendo el efecto de abortos anteriores, número de partos y edad, días abiertos al momento de la concepción y el efecto de la estación. Otros métodos analíticos de utilidad también serán presentados para el diagnóstico de hato de aborto relacionado con la exposición a agentes infecciosos o a otros factores. Estos métodos permiten estimar el riesgo o la proporción de abortos atribuibles a la exposición a un agente infeccioso o a cualquier otro agente que pueda producir aborto.

The purpose of the paper is to offer methods for use in measuring abortion rates and in undertaking abortion diagnostic investigations. In addition, some of the associations found between demographic and reproductive features of the dam and subsequent abortion will be described. The cohort life table method calculates the risk of fetal loss (abortion), for pre-defined time intervals (eg. days or weeks) during the gestation period, and the overall proportion of cows that abort. In contrast, the abortion density method calculates abortion risk for a defined calendar time (eg. per month) as the number of abortions per cow-days-at risk. Both methods are standardized to account for the changing number of cows at risk of abortion, as a result of culling, death, abortion, and calving, thus tend to produce higher, but more realistic, estimates for abortion than rates typically calculated. These measures and statistical modeling have been used to estimate the expected magnitude of abortion for dairies (ranging from 8% to 19%) and to identify associations between demographic or reproductive features of the dam and subsequent risk of abortion. Some of the factors to be discussed include effects of a previous abortion, dam gravidity and age, days open at the time of conception, and season. Analytic methods also will be presented for herd-based diagnosis of abortion related to infectious agents or other exposures. These methods permit estimates of the risk or proportion of abortions attributable to exposure to an infectious agent or to other putative abortifacient exposures.