Serogroups and genotypes of Leptospira spp. strains from bovine aborted foetuses.

Leptospirosis is a global disease of animals, with potential major economic impact on livestock industry and important zoonotic capacities. The disease represents a major challenge in the developing countries as humans and animals frequently live in close association. The serovar Hardjo of Leptospira whose primary host is cattle has been studied extensively, but few data exist on other current circulating or emerging serotypes. To better understand the disease in cattle and how to prevent and/or control it, it is necessary to identify the genotype and the serotype of circulating Leptospira. This study presents results of several investigations performed on a historical Belgian collection of congenital jaundice in bovine aborted foetuses coming from the leptospirosis emerging episode of 2014 (Delooz et al., Transboundary and Emerging Diseases, 62, 2015, 124). The results revealed that L. Grippotyphosa and L. Australis were the most prevalent serogroups with, respectively, 17/42 and 13/42 positive microscopic agglutination test (MAT) during this emerging event associated with the same clinical pattern. The study also confirms that congenital jaundice is associated with L. kirscheneri and L. interrogans and provides the genotyping of DNA obtained from these two species.

Schmallenberg Virus in Belgium: Estimation of Impact in Cattle and Sheep Herds.

Schmallenberg virus (SBV) emerged during summer 2011. SBV induced an unspecific syndrome in cattle and congenital signs (abortions, stillbirths and malformations) in domestic ruminants. To study the impact of SBV in Belgium, a phone survey was conducted upon September 2012. Hereto two groups of cattle farmers (A and B) and two groups of sheep farmers (C and D) were randomly selected. Farms from groups A (n = 53) and C (n = 42) received SBV-positive result at RT-PCR in the Belgian National Reference Laboratory (NRL). Farms from groups B (n = 29) and D (n = 44) never sent suspected samples to NRL for SBV analysis but were however presumed seropositive for SBV after the survey. Questionnaires related to reproduction parameters and clinical signs observed in newborn and adult animals were designed and addressed to farmers. As calculated on a basis of farmers' observations, 4% of calves in group A and 0.5% in group B were reported aborted, stillborn or deformed due to SBV in 2011-2012. The impact as observed by sheep farmers was substantially higher with 19% of lambs in group C and 11% in group D that were reported aborted, stillborn or deformed due to SBV in 2011-2012. Interestingly, abortions or stillbirths were not clear consequences of SBV outbreak in cattle farms, and the birth of a deformed animal was an essential condition to suspect SBV presence in cattle and sheep farms. This study contributes to a better knowledge of the impact of the SBV epidemic. The results suggest that SBV impacted Belgian herds mostly by the birth of deformed calves, stillborn lambs and deformed lambs. This work also demonstrates that the birth of a deformed calf or lamb was a trigger for the farmer to suspect the presence of SBV and send samples to NRL for further analyses.

Laboratory Findings Suggesting an Association Between BoHV-4 and Bovine Abortions in Southern Belgium.

Abortions cause heavy economic losses for the bovine sector. The use of a standardized panel of analyses covering a large spectrum of pathogens responsible of abortion in cattle allowed demonstrating the direct involvement of at least one pathogen in 57% of analysed abortions in the southern part of Belgium. This result suggests a margin of improvement in the diagnostic efficacy. In order to evaluate the interest to broaden the list of pathogens included in the panel of analyses, the implication of bovine herpesvirus 4 (BoHV-4) in abortion was assessed by two different studies. In the first study, coupled serology was performed after abortion on 714 dams to identify specific seroconversion against BoHV-4. The overall seroconversion in cows was 19.5%, with a higher frequency in primiparous compared to multiparous females. In addition, the type of breed (beef cattle) and the time period from the fourth quarter 2008 until the last quarter 2009 were significantly related to the seroconversion of cows. The second study investigated the virus ability to infect the foetus. In this study, 368 cases of bovine abortions were specifically tested for BoHV-4, using PCR on foetus tissues and ELISA on dam and foetus sera. The results showed a maternal seroprevalence of 64.7%, a foetal seroprevalence of 0.8% and a PCR prevalence in foetuses of 1.1%, demonstrating the ability of BoHV-4 to infect the foetus.

Resurgence of Schmallenberg Virus in Belgium after 3 Years of Epidemiological Silence.

In spring 2016, three years after the last reported outbreak of Schmallenberg virus (SBV) in Belgium, an abortion was notified in a two year old Holstein heifer that previously had not been vaccinated against SBV. The autopsy of the eight-month-old malformed foetus revealed hydrocephalus, torticollis and arthrogryposis. Foetal brain tissue and blood were found to be SBV-positive by RT-PCR and ELISA tests, respectively. Evidencing the circulation of SBV in Belgium in the autumn 2015 is important to anticipate future outbreaks and advise veterinarians about the risks associated with calving, as more bovine foetuses might have been infected.

Congenital jaundice in bovine aborted foetuses: an emerging syndrome in southern Belgium.

Southern Belgium faces an unusual recent increase of icteric bovine aborted foetuses. In the necropsy room, the majority of foetuses presented jaundice and splenomegaly. Despite a wide range of analyses, no definitive cause of abortion has yet been established but some analysis results support the leptospirosis hypothesis. This first description of cases will help veterinary practitioners to recognize more cases and to conduct those to the laboratory for future investigations.

Large-scale cross-sectional serological survey of Schmallenberg virus in Belgian cattle at the end of the first vector season.

A cross-sectional survey was conducted in the Belgian cattle population after the first period of infection of the emerging Schmallenberg virus. A total number of 11 635 cattle from 422 herds sampled between 2 January and 7 March 2012 were tested for the presence of Schmallenberg-specific antibodies using an ELISA kit. Between-herd seroprevalence in cattle was estimated at 99.76% (95% CI: 98.34-99.97) and within-herd seroprevalence at 86.3% (95% CI: 84.75-87.71). An Intraclass Correlation Coefficient of 0.3 (P < 0.001) was found, indicating that the correlation between two animals within a herd with respect to their serological status was high. Those results corroborate the conclusion that the Schmallenberg virus was widespread in Belgium during winter 2011. Seroprevalence was shown to be statistically associated to the animal's age (P < 0.0001): with 64.9% (95% CI: 61.34-68.3) estimated for the 6-12 months of age, 86.79% (95% CI: 84.43-88.85) for the 12-24 months of age and 94.4% (95% CI: 93.14-95.44) for the animals older than 24 months. Based on the results of the described serological survey, we can conclude that after the first Schmallenberg virus episode, almost every Belgian cattle has already been in contact with the virus. In consequence, the vast majority of the host animals should have developed post infection protective immunity against the virus.