Detection of Usutu virus infection in wild birds in the United Kingdom, 2020.

In August 2020, as part of a long-term disease surveillance programme, Usutu virus was detected in five Eurasian blackbirds (Turdus merula) and one house sparrow (Passer domesticus) from Greater London, England. This was initially detected by reverse transcription-PCR and was confirmed by virus isolation and by immunohistochemical detection of flavivirus in tissues. Phylogenetic analysis identified Usutu virus African 3.2 lineage, which is prevalent in the Netherlands and Belgium, suggesting a potential incursion from mainland Europe.

The effects of torula yeast as a protein source on apparent total tract digestibility, inflammatory markers, and fecal microbiota dysbiosis index in Labrador Retrievers with chronically poor stool quality.

This study examined the effects of varying protein sources on apparent total tract digestibility, inflammatory markers, and fecal microbiota in Labrador Retrievers with historically poor stool quality. Thirty dogs (15 male, 15 female; aged 0.93 to 11.7 yr) with stool quality scores ≤2.5 on a 5-point scale (1 representing liquid stool and 5 representing firm stool) were randomly assigned to 1 of 3 nutritionally complete diets with differing protein sources and similar macronutrient profiles: 1) chicken meal (n = 10); 2) 10% brewer's yeast (n = 10); or 3) 10% torula yeast (n = 10). Another 10 dogs (five male, five female) with normal stool quality (scores ranging from 3 to 4) received diet 1 and served as negative control (NC). All dogs were fed diet 1 for 7 days, then provided their assigned treatment diets from days 7 to 37. Daily stool scores and weekly body weights were recorded. On days 7, 21, and 36, blood serum was analyzed for c-reactive protein (CRP), and feces for calgranulin C (S100A12), α1-proteinase inhibitor (α1-PI), calprotectin, and microbiota dysbiosis index. Apparent total tract digestibility was assessed using the indicator method with 2 g titanium dioxide administered via oral capsules. Stool scores were greater in NC (P < 0.01) as designed but not affected by treatment × time interaction (P = 0.64). Body weight was greater (P = 0.01) and CRP lower (P < 0.01) in NC dogs. Dry matter and nitrogen-free extract digestibility did not differ among groups (P ≥ 0.14). Negative controls had greater fat digestibility compared to BY (94.64 ±â€…1.33% vs. 91.65 ±â€…1.25%; P = 0.02). The overall effect of treatment was significant for protein digestibility (P = 0.03), but there were no differences in individual post hoc comparisons (P ≥ 0.07). Treatment did not affect S100A12 or α1-PI (P ≥ 0.44). Calprotectin decreased at a greater rate over time in TY (P < 0.01). The dysbiosis index score for BY and TY fluctuated less over time (P = 0.01). Blautia (P = 0.03) and Clostridium hiranonis (P = 0.05) abundances were reduced in BY and TY. Dogs with chronically poor stool quality experienced reduced body weights and increased serum CRP, but TY numerically increased protein digestibility, altered the microbiome, and reduced fecal calprotectin. Torula yeast is a suitable alternative protein source in extruded canine diets, but further research is needed to understand the long-term potential for improving the plane of nutrition and modulating gut health.

Pet and human populations continue to grow and compete for nutritious, sustainable protein sources. The incorporation of alternative proteins like torula yeast can provide a solution to this problem. Torula yeast also may have additional health benefits like reducing gut inflammation. To test its effects in dogs, we fed Labrador Retrievers with chronically poor stool quality either a control diet with chicken meal, a diet with 10% brewer's yeast, or a diet with 10% torula yeast. We compared their responses to dogs with normal stool quality fed the control diet. Dogs with chronically poor stool quality had lower body weights and increased systemic inflammation compared to those with good stool quality. Calprotectin, a marker of gut inflammation, was reduced more in dogs fed torula yeast than in dogs fed chicken meal. Torula and brewer's yeast also changed the abundance of certain gut bacteria. Torula yeast may be added to dog diets with no negative effects and can alter the gut environment in Labrador Retrievers with chronically poor stool quality.

JMM Profile: West Nile virus.

West Nile virus (WNV) is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family and is maintained in an enzootic cycle between avian hosts and mosquito vectors. Humans, horses and other mammals are susceptible to infection but are dead-end hosts due to a low viraemia. The disease can manifest itself in a variety of clinical signs and symptoms in people and horses from mild fever to severe encephalitis and morbidity. There are no vaccines licensed for human protection, but parts of Europe, North America, Africa and Australia have vaccines commercially available for horses.

Combining host and vector data informs emergence and potential impact of an Usutu virus outbreak in UK wild birds.

Following the first detection in the United Kingdom of Usutu virus (USUV) in wild birds in 2020, we undertook a multidisciplinary investigation that combined screening host and vector populations with interrogation of national citizen science monitoring datasets to assess the potential for population impacts on avian hosts. Pathological findings from six USUV-positive wild passerines were non-specific, highlighting the need for molecular and immunohistochemical examinations to confirm infection. Mosquito surveillance at the index site identified USUV RNA in Culex pipiens s.l. following the outbreak. Although the Eurasian blackbird (Turdus merula) is most frequently impacted by USUV in Europe, national syndromic surveillance failed to detect any increase in occurrence of clinical signs consistent with USUV infection in this species. Furthermore, there was no increase in recoveries of dead blackbirds marked by the national ringing scheme. However, there was regional clustering of blackbird disease incident reports centred near the index site in 2020 and a contemporaneous marked reduction in the frequency with which blackbirds were recorded in gardens in this area, consistent with a hypothesis of disease-mediated population decline. Combining results from multidisciplinary schemes, as we have done, in real-time offers a model for the detection and impact assessment of future disease emergence events.

Equine seroprevalence of West Nile virus antibodies in the UK in 2019.

BACKGROUND: West Nile virus (WNV) is a single-stranded RNA virus that can cause neurological disease in both humans and horses. Due to the movement of competent vectors and viraemic hosts, WNV has repeatedly emerged globally and more recently in western Europe. Within the UK, WNV is a notifiable disease in horses, and vaccines against the virus are commercially available. However, there has been no investigation into the seroprevalence of WNV in the UK equine population to determine the extent of vaccination or to provide evidence of recent infection. METHODS: Equine serum samples were obtained from the Animal and Plant Health Agency's equine testing service between August and November 2019. A total of 988 serum samples were selected for horses resident in South East England. WNV seroprevalence was determined using two enzyme-linked immunosorbent assays (ELISAs) to detect total flavivirus antibodies and WNV-specific immunoglobulin M (IgM) antibodies. Positive IgM results were investigated by contacting the submitting veterinarian to establish the clinical history or evidence of prior vaccination of the horses in question. RESULTS: Within the cohort, 274 samples tested positive for flavivirus antibodies, of which two subsequently tested positive for WNV-specific IgM antibodies. The follow-up investigation established that both horses had been vaccinated prior to serum samples being drawn, which resulted in an IgM-positive response. All the samples that tested positive by competition ELISA were from horses set to be exported to countries where WNV is endemic. Consequently, the positive results were likely due to previous vaccination. In contrast, 714 samples were seronegative, indicating that the majority of the UK equine population may be susceptible to WNV infection. CONCLUSIONS: There was no evidence for cryptic WNV infection in a cohort of horses sampled in England in 2019. All IgM-seropositive cases were due to vaccination; this should be noted for future epidemiological surveys in the event of a disease outbreak, as it is not possible to distinguish vaccinated from infected horses without knowledge of their clinical histories.

High seroprevelance of West Nile virus antibodies observed in horses from southwestern Nigeria.

To investigate exposure of Nigerian horses to West Nile virus (WNV), we determined the seroprevalence rate of anti-WNV antibody in a cohort of 145 horses. Serum samples were collected from three locations in southwestern Nigeria between October, 2011, and July, 2012. The horses were asymptomatic and unvaccinated against WNV at the time of sampling. All sera were tested using a competition enzyme-linked immmunosorbent assay (ELISA) and by an immunoglobulin M (IgM)-specific ELISA. High rates of anti-WNV antibody prevalence were observed in all locations with a mean level of 90.3% (95% confidence interval 84.3-94.6%). None of the horses had detectable anti-WNV IgM. This is the first ELISA-based report of WNV seroprevalence in Nigerian horses and suggests that WNV is enzootic in the study areas, indicating a potential risk of infection in humans and animals.

Enhanced West Nile virus surveillance in the North Kent marshes, UK.

BACKGROUND: As part of efforts to more fully understand the potential risks posed by West Nile virus (WNV) and Usutu virus (USUV) in the UK, and following on from previous reports of a potential bridge vector Culex modestus for these viruses, at wetland sites in North Kent, mosquito surveillance was undertaken more widely across the Isle of Sheppey, the Hoo Peninsula and the Kent mainland. METHODS: Larval surveys were conducted and Mosquito Magnet® adult traps were used to collect adult mosquitoes. Pools of female mosquitoes were tested for the presence of WNV using real-time reverse transcriptase polymerase chain reaction. A subset of samples was tested for USUV. RESULTS: Culex modestus was found in both the pre-imaginal and imago stage at all five locations surveyed, accounting for 90% of adult mosquitoes collected. WNV or USUV were not detected in any sample. CONCLUSIONS: Although no mosquitoes have been shown to be virus positive, the field survey data from this study demonstrated the dominance of an important bridge vector species for WNV in this region. Its wide geographical distribution highlights the need to update risk assessments on WNV introduction, and to maintain vigilance for WNV in the South East of England.

Assessment of a novel real-time pan-flavivirus RT-polymerase chain reaction.

Outbreaks of West Nile virus (WNV) have occurred intermittently in regions around the Mediterranean coast, and the virus may have become established in Northern Italy and Romania, with reported intermittent outbreaks in Spain, Hungary, and France. WNV has also spread rapidly throughout the Americas since its introduction into New York in 1999. This capacity to emerge in new geographical locations and to spread rapidly together with the current increase in incidence of other flaviviruses such as tick-borne encephalitis virus, dengue virus, and Usutu virus has prompted us to design a novel pan-flavivirus RT-polymerase chain reaction for the purpose of surveillance for a range of flaviviruses. The assay utilizes degenerate primers targeting the flavivirus NS5 gene (RNA-dependent RNA polymerase) and detects a range of flaviviruses, including WNV. A small panel of WNV bird samples obtained from the United States has been shown to be detected using this assay. The amplicon generated is of sufficient size to provide sequence data to confirm the identity of the virus detected and undertake limited phylogenetic analysis. Testing using this assay has shown its ability to detect a range of tick-borne flaviviruses, particularly louping ill virus that is endemic in areas of the United Kingdom. The assay has been used to survey 160 bird samples and 1000 mosquito samples from the United Kingdom and found no evidence for WNV.