Schmallenberg virus: a systematic international literature review (2011-2019) from an Irish perspective

Abstract

In Autumn 2011, nonspecific clinical signs of pyrexia, diarrhoea, and drop in milk yield were observed in dairy cattle near the German town of Schmallenberg at the Dutch/German border. Targeted veterinary diagnostic investigations for classical endemic and emerging viruses could not identify a causal agent. Blood samples were collected from animals with clinical signs and subjected to metagenomic analysis; a novel orthobunyavirus was identified and named Schmallenberg virus (SBV). In late 2011/early 2012, an epidemic of abortions and congenital malformations in calves, lambs and goat kids, characterised by arthrogryposis and hydranencephaly were reported in continental Europe. Subsequently, SBV RNA was confirmed in both aborted and congenitally malformed foetuses and also in Culicoides species biting midges. It soon became evident that SBV was an arthropod-borne teratogenic virus affecting domestic ruminants. SBV rapidly achieved a pan-European distribution with most countries confirming SBV infection within a year or two of the initial emergence. The first Irish case of SBV was confirmed in the south of the country in late 2012 in a bovine foetus. Since SBV was first identified in 2011, a considerable body of scientific research has been conducted internationally describing this novel emerging virus. The aim of this systematic review is to provide a comprehensive synopsis of the most up-to-date scientific literature regarding the origin of SBV and the spread of the Schmallenberg epidemic, in addition to describing the species affected, clinical signs, pathogenesis, transmission, risk factors, impact, diagnostics, surveillance methods and control measures. This review also highlights current knowledge gaps in the scientific literature regarding SBV, most notably the requirement for further research to determine if, and to what extent, SBV circulation occurred in Europe and internationally during 2017 and 2018. Moreover, recommendations are also made regarding future arbovirus surveillance in Europe, specifically the establishment of a European-wide sentinel herd surveillance program, which incorporates bovine serology and Culicoides entomology and virology studies, at national and international level to monitor for the emergence and re-emergence of arboviruses such as SBV, bluetongue virus and other novel Culicoides-borne arboviruses.

Multiple Cephalic Malformations in a Calf

“…Moreover, the calf of the present study tested negative for BVDV, Blue tongue virus, and Shmallenberg virus at rtPCR. Akabane virus and Aino virus were not investigated because they are not currently reported in Italy [22][23][24].…”

Aptamers for Detection and Diagnostics (ADD) is a proposed mobile app acquiring optical data from conjugated quantum nanodots to identify molecules indicating presence of SARS-CoV-2 virus: Why public health and healthcare need smartphone sensors as a platform for early detection and prevention

“…What does it mean? Compared to diseases 190 due to relatively unknown viruses 191 , and despite the flu pandemic ~100 years ago, the coronavirus, in less than six months, has changed, perhaps permanently, global thinking, trends and technology. Tobacco Mosaic Virus (TMV) was discovered around 1890-1892 192 but after more than 100 years 193 of virus discovery, we have just now acknowledged the threat to global health from viruses.…”

Investigation of bovine abortion and stillbirth/perinatal mortality - similar diagnostic challenges, different approaches

“…Abortion (20 to 50% [ 5 ];) and stillbirth (30 to 75% [ 6 ];), diagnosis rates do not appear to have improved over time internationally despite the development of molecular diagnostic techniques and the discovery of new foetopathogens, e.g. Schmallenberg virus [ 7 ]. While reasons for the overall low diagnostic rates from foetal investigations are detailed hereunder, this paper addresses this challenging conundrum with a view to veterinary practitioner-led improvements in diagnostic rates.…”