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In July 2024, bluetongue virus serotype 3 (BTV-3) was first detected in southern Belgium, marking the onset of a major epidemic wave. This study documents, for the first time in Belgium, the ability of BTV-3 to cross the placental barrier in cattle, causing abortions and congenital central nervous system malformations. Abortion cases from January to December 2024 were monitored through the national abortion protocol, which mandates reporting and laboratory investigation (i.e., the year of emergence and the three previous years as the baseline data set). Among 5,751 reported abortions, 903 foetuses were tested by PCR, revealing widespread BTV-3 circulation. The first malformed PCR-positive foetus was recorded in mid-August, four weeks after a sharp increase in abortion rates. Lesions such as hydranencephaly were confirmed in PCR-positive foetuses, with a malformation rate of 32.24% in affected herds from weeks 36 to 52 (i.e., 22 times higher than in previous years). Gestational stage analysis indicated that congenital lesions were most frequent following infection between 70 and 130 days of gestation. Based on the observed gross lesions and the timing of abortion, it was deduced that the earliest maternal infections likely occurred in February–March 2024, implying low-level winter BTV-3 circulation before the official detection of the epidemic wave. These findings highlight the epidemiological value of systematic abortion monitoring as an early warning system tool and highlight the inadequacy of relying solely on clinical surveillance in adult ruminants. The abrupt emergence of BTV-3 across the territory without a gradual spatial spread underscores the need for anticipatory control strategies. Strategic, multivalent vaccination campaigns and enhanced abortion surveillance are critical to mitigate similar reproductive and economic losses in future bluetongue outbreaks.

Background Coxiella burnetii , Chlamydia abortus and Leptospira spp. are difficult to grow bacteria that play a role in bovine abortion, but their diagnosis is hampered by their obligate intracellular lifestyle ( C. burnetii , C. abortus ) or their lability ( Leptospira spp.). Their importance is based on the contagious spread in food-producing animals, but also as zoonotic agents. In Switzerland, first-line routine bacteriological diagnostics in cattle abortions is regulated by national law and includes only basic screening by staining for C. burnetii due to the high costs associated with extended spectrum analysis. The aim of this study was to assess the true occurrence of these zoonotic pathogens in 249 cases of bovine abortion in Switzerland by serology (ELISA for anti- C. burnetii and C. abortus antibodies and microscopic agglutination test for anti- Leptospira spp. antibodies), molecular methods (real-time PCR and sequencing of PCR products of Chlamydiales- positive cases), Stamp’s modification of the Ziehl-Neelsen (mod-ZN) stain and, upon availability of material, by histology and immunohistochemistry (IHC). Results After seroanalysis the prevalence was 15.9% for C. burnetii , 38.5% for C. abortus and 21.4% for Leptospira spp. By real-time PCR 12.1% and 16.9% of the cases were positive for C. burnetii and Chlamydiales , respectively, but only 2.4% were positive for C. burnetii or Chlamydiales by mod-ZN stain. Sequencing of PCR products of Chlamydiales- positive cases revealed C. abortus in 10% of cases and the presence of a mix of Chlamydiales -related bacteria in 5.2% of cases. Pathogenic Leptospira spp. were detected in 5.6% of cases. Inflammatory lesions were present histologically in all available samples which were real-time PCR-positive for Chlamydiales and Leptospira spp. One of 12 real-time PCR-positive cases for C. burnetii was devoid of histological lesions. None of the pathogens could be detected by IHC. Conclusion Molecular detection by real-time PCR complemented by histopathological analysis is recommended to improve definitive diagnosis of bovine abortion cases and determine a more accurate prevalence of these zoonotic pathogens.

Latency is a key feature of the animal pathogen Chlamydia abortus, where infection remains inapparent in the non-pregnant animal and only becomes evident during a subsequent pregnancy. Often the first sign that an animal is infected is abortion occurring late in gestation. Despite this, little is understood of the underlying mechanisms that control latency or the recrudescence of infection that occurs during subsequent pregnancy. The aim of this study was to develop an experimental model of latency by mimicking the natural route of infection through the intranasal inoculation of non-pregnant sheep with C. abortus. Three groups of sheep (groups 1, 2 and 3) were experimentally infected with different doses of C. abortus (5×10(3), 5×10(5) and 5×10(7) inclusion forming units (IFU), respectively) prior to mating and monitored over 2 breeding cycles for clinical, microbiological, pathological, immunological and serological outcomes. Two further groups received either negative control inoculum (group 4a,b) or were inoculated subcutaneously on day 70 of gestation with 2×10(6) IFU C. abortus (group 5). Animals in groups 1, 2 and 5 experienced an abortion rate of 50-67%, while only one animal aborted in group 3 and none in group 4a,b. Pathological, microbiological, immunological and serological analyses support the view that the maternal protective immune response is influenced by initial exposure to the bacterium. The results show that intranasal administration of non-pregnant sheep with a low/medium dose of C. abortus results in a latent infection that leads in a subsequent pregnancy to infection of the placenta and abortion. In contrast a high dose stimulates protective immunity, resulting in a much lower abortion rate. This model will be useful in understanding the mechanisms of infection underlying latency and onset of disease, as well as in the development of novel therapeutics and vaccines for controlling infection.

Abortion is one of the major threats to the livestock industry, and it also poses significant threats to public health since some of the abortifacient agents are considered zoonotic. Chlamydia abortus (C. abortus), Coxiella burnetii (C. burnetii), Listeria monocytogenes (L. monocytogenes), and Cache Valley virus (CVV) are recognized as important zoonotic and abortifacient agents of reproductive failure in small ruminants. This study determined the prevalence of these agents in ovine and caprine foetuses in Türkiye. A total of 1 226 foetuses were collected from the sheep (n = 1 144) and goats (n = 82) from different flocks between 2012 and 2017. Molecular detection methods were used to detect C. abortus, C. burnetii, and L. monocytogenes DNA and CVV RNA in aborted foetuses. In this study, C. abortus was the most prevalent abortifacient agent among the investigated ovine (264/1144) and caprine (12/82) foetuses, followed by C. burnetii with a frequency of 2.8% (32/1144) and 8.5% (7/82) in ovine and caprine foetuses, respectively. L. monocytogenes DNA was detected in 28 (2.4%) and 2 (2.4%) of the ovine and caprine foetuses, respectively. However, CVV RNA was not detected. Although the predominant mixed infection was C. abortus and C. burnetii, mixed infection of C. abortus and L. monocytogenes, and C. burnetii and L. monocytogenes were also found. The information presented in this study contributes to the understanding of the roles of C. abortus, C. burnetii, L. monocytogenes, and CVV in abortions in small ruminants, and could be beneficial for developing more effective control strategies.

A six-year study on water buffaloes from the Campania Region (Southern Italy) was conducted to evaluate the presence of bovine/bubaline herpesviruses in cases of abortion. A total of 244 buffalo foetuses were analysed by real-time PCR to detect the presence of: bovine alphaherpesvirus 1(BoHV-1), bubaline alphaherpesvirus 1 (BuHV-1), bovine alphaherpesvirus 2 (BuHV-2), and bovine gammaherpesvirus 4 (BoHV-4). The foetuses of 14 water buffaloes that showed abortions were positive for BuHV-1 (4 animals) and/or BoHV-4 (11 animals), with one of these cases showing co-infection with BuHV-1 and BoHV-4. This study reports the first identification of BoHV-4 in water buffaloes. Cases of abortion were analysed using both molecular and cultural assays for the presence of other pathogens. In nearly all the abortion cases positive for BoHV-4, the virus was identified as a co-infecting agent together with other microorganisms, whereas in two abortion cases, it was the only pathogen found.

Background The threat of zoonotic diseases is significant to global public health. Campylobacter spp., Coxiella burnetii (C. burnetii), Brucella spp., Listeria monocytogenes (L. monocytogenes), Chlamydia abortus (C. abortus), and Cache Valley virus (CVV) play a role in bovine abortion and are transmitted from animals to humans. Objective This study aimed to investigate the presence of these zoonotic abortifacient agents in bovine foetuses (n = 125), each from different herds, in a three‐year period in Türkiye. Methods The detection and differentiation of Brucella spp. was achieved using a PCR method, while a multiplex PCR assay was used to detect and differentiate Campylobacter spp. Real‐time PCR assays were used to detect C. burnetii, C. abortus, and L. monocytogenes. Furthermore, samples were tested for CVV using one‐step duplex real‐time RT‐PCR. Results Although L. monocytogenes and C. abortus and CVV were not detected, Brucella spp., Campylobacter spp., and C. burnetii were detected in 19 (15.2%), 4 (3.2%), and 2 (1.6%) of the bovine foetuses, respectively. Brucella and Campylobacter species were identified by molecular testing as B. melitensis (n = 4) and B. abortus (n = 15) and C. jejuni (n = 2) and C. foetus subsp. foetus (n = 2), respectively. Conclusions The findings of this study suggest that Brucella spp., Campylobacter spp., and C. burnetii could pose a threat to both cattle and human health in the studied regions. Further studies are required to determine the exact role of these agents in cattle reproductive losses in Türkiye, as well as the economic impact of these agents on livestock. This study aimed to investigate the presence of Campylobacter spp., Coxiella burnetii, Brucella spp., Listeria monocytogenes, Chlamydia abortus, and Cache Valley virus in bovine foetuses in Türkiye. Brucella spp., Campylobacter spp. and Coxiella burnetii were detected in 19 (15.2%), 4 (3.2%) and 2 (1.6%) of the bovine foetuses, respectively. Brucella and Campylobacter species were identified by molecular testing as B. melitensis (n = 4) and B. abortus (n = 15) and C. jejuni (n = 2) and C. foetus subsp. foetus (n = 2), respectively.

Background Cattle abortion, which may be caused by different infectious agents, harms milk and meat production, animal health, and ultimately rural economies. Despite the existence of a national control program for cattle brucellosis since 1995, abortion remains a major concern for cattle breeders in Algeria even among officially recognized cattle Brucellosis-free herds. The objective of this study is to investigate i: the abortion rate among officially recognized cattle Brucellosis-free herds, ii: the seroprevalence of some abortive infectious agents within cattle Brucellosis-free herds, iii: evaluate the abortion risk factors associated with the seropositivity of the investigated abortive agents among brucellosis cattle-free herds. Results The present study reveals an abortion rate at the herd and the individual level of 47, 36% (20/38) and 29, 06% (50/172) respectively. Herd seroprevalences were as follows: neosporosis (31,57%), toxoplasmosis (28,94%); chlamydiosis (Chlamidophila abortus) (15,78% ); Q fever ( Coxiella burnetii ) (47,36%); Bovine viral diarrhea (BVD) (60,52%) and infectious bovine rinotracheitis (IBR) (42,10%). The risk factor analysis using a multivariable logistic regression model at the herd level showed that seropositivity to neosporosis (OR = 1, 11, CI: [0,85 − 1,19]); toxoplasmosis (OR = 1,95, CI: [1,22 − 2,84]); IBR (OR = 1,78, CI: [1,59 − 2,79]); BVD (OR = 1,65, CI: [1,86 − 3,43]); Q fever (OR = 1,51, CI: [1,42 − 2,53]) is a risk factor for abortion. Additionally, our findings reveal that the presence of co-infection is also a risk factor for abortion among Algerian Brucellosis-free herds. The risk for abortion at the herd level was 1,41 times higher for double and triple-infected herds and 1,65 times higher for quintuple-infected herds compared to negative. Moreover, managerial factors, such as hygiene practices on farms, the presence of primiparous cows, and mixed breeding livestock, were identified as additional risk factors for abortion. Conclusion Based on these results, particular attention should be given to the studied abortive agents to strengthen the prevention and control plan. Furthermore, establishing some preventive measures such as quarantine and biosecurity could help reduce infections in dairy farms.

Background No comprehensive studies have been carried out on the infectious causes of abortion in Kenyan dairy cattle herds. A survey was carried out to determine the seroprevalence of antibodies against Bovine Viral Diarrhoea Virus (BVDV), Brucella abortus (BA) and Neospora caninum (NC) among dairy cattle herds in Nakuru County, a major dairying area in Kenya. A prospective sero-epidemiological study was also undertaken to investigate the effects of BVDV, BA and NC on the occurrence of bovine abortion in dairy cattle herds, where monthly rectal palpations for pregnancy were performed, and monthly serum samples were tested for antibodies to the 3 pathogens. Results In the 398 randomly selected cattle on 64 dairy herds, the seroprevalences of antibodies to BVDV, NC and BA were 79.1, 25.6 and 16.8%, respectively. Of the cattle seropositive to NC, 83.3% were also seropositive to BVDV and 13.7% to BA. Of the cattle seropositive to BVDV, 17.1% were also seropositive to BA. Among 260 monitored pregnant dairy cattle on the same 64 dairy farms, an incidence risk for abortion of 10.8% (28/260) was identified, while the incidence of other foetal losses was 1.1% (3/260). The incidence rates of sero-conversion for NC, BVD and BA were 1.1, 0.06 and 0.5 new infections/100 cow-months at risk, respectively. The foetal losses were mainly observed in animals less than 96 months old and occurred in mid-gestation. Neospora caninum was associated with most cases (29.0%) of foetal losses, followed by mixed infections of NC and BVDV (12.9%), BVDV (9.9%) and co-infections of BA and NC (6.5%). Conclusions This is the first study to document the substantial incidence risk of BVDV and NC abortions in dairy cattle in Kenya, and demonstrates the relative importance of BA, BVDV and NC infections in dairy cattle in Kenya. Kenya laboratories should offer diagnostic tests for BVDV and NC to help farmers determine their roles in abortions on their farms. A comprehensive policy on the control of these important diseases should also be put in place by government with the involvement of all stakeholders in the dairy cattle industry.

Coxiella burnetii is the causative agent of Q fever which is a highly infectious zoonotic disease. C. burnetii has become one of the most important causes of abortion in livestock, which can lead to widespread abortions in these animals. There are very limited studies on the prevalence of C. burnetii infection in cases of animal abortion in Iran. The aim of this study was to investigate the occurrence of C. burnetii in ruminant abortion samples in Iran. Abortion samples from cattle, sheep and goats were collected from different parts of Iran and were tested using Real-time PCR targeting the IS1111 element of C. burnetii. In this study, 36 samples (24.7%) of the 146 collected samples were positive for C. burnetii. The prevalence of C. burnetii was 21.3% (20 of 94 samples) in sheep samples. Also, 10 of 46 cattle samples (21.7%) were positive. All six goat abortion samples were positive for C. burnetii. The findings of the study demonstrate that C. burnetii plays an important role in domestic ruminant abortions in Iran, suggesting that more attention should be paid to the role of C. burnetii in domestic animal abortions by veterinary organizations. The risk of transmitting the infection to humans due to abortion of animals should also be considered.

Livestock abortion is an important cause of productivity losses worldwide and many infectious causes of abortion are zoonotic pathogens that impact on human health. Little is known about the relative importance of infectious causes of livestock abortion in Africa, including in subsistence farming communities that are critically dependent on livestock for food, income, and wellbeing. We conducted a prospective cohort study of livestock abortion, supported by cross-sectional serosurveillance, to determine aetiologies of livestock abortions in livestock in Tanzania. This approach generated several important findings including detection of a Rift Valley fever virus outbreak in cattle; high prevalence of C. burnetii infection in livestock; and the first report of Neospora caninum , Toxoplasma gondii, and pestiviruses associated with livestock abortion in Tanzania. Our approach provides a model for abortion surveillance in resource-limited settings. Our findings add substantially to current knowledge in sub-Saharan Africa, providing important evidence from which to prioritise disease interventions.