The prevalence of atypical scrapie in sheep from positive flocks is not higher than in the general sheep population in 11 European countries

Background: During the last decade, active surveillance for transmissible spongiform encephalopathies in small ruminants has been intensive in Europe. In many countries this has led to the detection of cases of atypical scrapie which, unlike classical scrapie, might not be contagious. EU legislation requires, that following detection of a scrapie case, control measures including further testing take place in affected flocks, including the culling of genotype susceptible to classical scrapie. This might result in the detection of additional cases. The aim of this study was to investigate the occurrence of additional cases in flocks affected by atypical scrapie using surveillance data collected in Europe in order to ascertain whether atypical scrapie, is contagious. Results: Questionnaires were used to collect, at national level, the results of active surveillance and testing associated with flock outbreaks in 12 European countries. The mean prevalence of atypical scrapie was 5.5 (5.0-6.0) cases per ten thousand in abattoir surveillance and 8.1 (7.3-9.0) cases per ten thousand in fallen stock. By using meta-analysis, on 11 out of the 12 countries, we found that the probability of detecting additional cases of atypical scrapie in positive flocks was similar to the probability observed in animals slaughtered for human consumption (odds ratio, OR = 1.07, CI95%: 0.70-1.63) or among fallen stock (OR = 0.78, CI95%: 0.51-1.2). In contrast, when comparing the two scrapie types, the probability of detecting additional cases in classical scrapie positive flocks was significantly higher than the probability of detecting additional cases in atypical scrapie positive flocks (OR = 32.4, CI95%: 20.7-50.7). Conclusions: These results suggest that atypical scrapie is not contagious or has a very low transmissibility under natural conditions compared with classical scrapie. Furthermore this study stressed the importance of standardised data collection to make good use of the analyses undertaken by European countries in their efforts to control atypical and classical scrapie

First description of a fatal equine infection with Halicephalobus gingivalis in Portugal. Relevance for public health.

Research Areas: Veterinary SciencesABSTRACT - Halicephalobus gingivalisis a small saprophytic rhabditid nematode, represented only by females with a typicalrhabditoid oesophagus and one egg in the uterus, capable of infecting vertebrates. This opportunistic parasitepresent in the soil, manure and decaying humus, is thought to penetrate through previous injuries to the mouth,eyes and skin of horses and migrate to various organs. The brain is one such organ, where the females lay theireggs, leading to malacia and causing a sudden onset of neurological signs, such as anorexia, ataxia, urinaryincontinence, blindness, decreased menace and tonal reflexes, tremors and aggressiveness. The disease isinvariably fatal whenever brain lesions are present, and the diagnosis usually achieved only post-mortem. Thepresent work aims to describe the first case of infection byH. gingivalisever reported in Portugal. An 8-yearold warmblood horse presented with an 8-day history of progressive blindness involving the left eye, initiallywith normal pupillary reflexes, advancing to bilateral blindness and increasing deterioration in clinical condi-tion. After euthanasia, the animal was submitted for necropsy. Organ samples were collected and fixed in 10%neutral buffered formalin for routine histopathology. A large mass was found in the left kidney correspondingto fibrous tissue heavily infiltrated with inflammatory cells and numerous nematodes. In the brain, multiple,bilateral and asymmetrical foci of malacia containing several rhabditoid nematodes, larvae and zygotes, andhigh numbers of inflammatory cells were found. The nematodes were identified asH. gingivalis.The clinicalhistory, necropsy and histological findings presented constitute a typical case ofH. gingivalisinfection in ahorse, never previously described in Portugal to the authors’ best knowledge. Humans can be infected bycontact with contaminated manure, which makes this nematode a public health concern, especially for peopleliving and/or working in close proximity to horses.info:eu-repo/semantics/publishedVersio

Fatal toxoplasmosis in a captive squirrel monkey (Saimiri boliviensis) in Portugal

8 páginas, 1 tabla, 3 figuras.New World monkeys are especially vulnerable to develop severe clinical manifestations and succumb to acute toxoplasmosis. This study aimed to describe the histopathological findings and genotypic characterization of the Toxoplasma gondii strain involved in a lethal case occurring in a zoo-housed black-capped squirrel monkey (Saimiri boliviensis) in Portugal. Cyst-like structures suggestive of Sarcocystidae parasites and acute injuries in liver and brain were observed by light microscopy examination. By immunohistochemistry, calprotectin, T. gondii antigen and Iba1 antigen had a positive signaling in lung, liver and brain tissues. Toxoplasma gondii B1, ITS1 and 529 repetitive element fragments amplifications together with the genotyping of 13 microsatellite markers confirmed a systemic T. gondii infection linked to a non-clonal type II strain. This description is consistent to the majority T. gondii strains circulating in Europe.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. LMO-M, and RC-B are part of the TOXOSOURCES consortium supported by the funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Grant Agreement No 773830: One Health European Joint Programme.Peer reviewe

TSE Monitoring in Wildlife Epidemiology, Transmission, Diagnosis, Genetics and Control

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now the rising concern within Europe. CWD will be outlined in this chapter gathering its epidemiology, transmission, diagnosis, genetics, and control. Prion diseases are fatal neurodegenerative diseases characterized by the accumulation of an abnormal isoform of the prion protein (PrPc), usually designated by PrPsc or prion. CWD is a prion disease of natural transmission affecting cervids detected mainly in North America. The first European case was detected in Norway, in 2016, in a wild reindeer; until April 2018, a total of 23 cases were described. The definite diagnosis is postmortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. It is not possible to establish a culling plan based on the genotype, once affected animals appear with all genotypes. However, some polymorphisms seem to result in longer incubation periods or confer a reduced risk. The control is not easy in captive cervids and even more in the wildlife; some recommendations have been proposed in order to understand the danger and impact of CWD on animal and public health

Neuropathology of animal prion diseases

Transmissible Spongiform Encephalopathies (TSEs) or prion diseases are a fatal group of infectious, inherited and spontaneous neurodegenerative diseases affecting human and animals. They are caused by the conversion of cellular prion protein (PrPC) into a misfolded pathological isoform (PrPSc or prion- proteinaceous infectious particle) that self-propagates by conformational conversion of PrPC. Yet by an unknown mechanism, PrPC can fold into different PrPSc conformers that may result in different prion strains that display specific disease phenotype (incubation time, clinical signs and lesion profile). Although the pathways for neurodegeneration as well as the involvement of brain inflammation in these diseases are not well understood, the spongiform changes, neuronal loss, gliosis and accumulation of PrPSc are the characteristic neuropathological lesions. Scrapie affecting small ruminants was the first identified TSE and has been considered the archetype of prion diseases, though atypical and new animal prion diseases continue to emerge highlighting the importance to investigate the lesion profile in naturally affected animals. In this report, we review the neuropathology and the neuroinflammation of animal prion diseases in natural hosts from scrapie, going through the zoonotic bovine spongiform encephalopathy (BSE), the chronic wasting disease (CWD) to the newly identified camel prion disease (CPD).info:eu-repo/semantics/publishedVersio

Chronic wasting disease risk assessment in Portugal: analysis of variability and genetic structure of the Portuguese roe deer population

Among the Transmissible Spongiform Encephalopathies, Chronic Wasting Disease (CWD) in cervids is now the rising concern in wildlife within Europe after the first case detected in Norway in 2016. CWD shows a notable horizontal transmission, affecting both free-ranging and captive cervids. Furthermore, several genetic variants in the Prion Protein (PRNP) gene coding sequence of the cervid were identified, which increase the susceptibility to the disease.This work was supported by the project WastingPrionRisk [POCI-01-0145-FEDER-029,947/ PTDC/CVT-CVT/29947/2017] funded by the Portuguese Foundation for Science and Technology (FCT). FCT PhD grant [SFRH/BD/146961/2019] financed by FCT through FSE (Fundo Social Europeu). This work was also supported by national funds [UIDB/CVT/00772/2020], [LA/P/0059/2020] and [UIDB/04033/2020] by FCT.info:eu-repo/semantics/publishedVersio

Scrapie at abattoir: monitoring, control, and differential diagnosis of wasting conditions during meat inspection

Wasting disease in small ruminants is frequently detected at slaughterhouses. The wasting disorder is manifested by the deterioration of the nutritional and physiological state of the animal indicated by thinness, emaciation, and cachexia. Evidence of emaciation and cachexia, alone, are pathological conditions leading to carcass condemnation during an inspection. Several diseases are associated with a wasting condition, including scrapie, pseudotuberculosis, tuberculosis, paratuberculosis, Maedi Visna, and tumor diseases. On the other hand, parasitic diseases, nutrition disorders, exposure or ingestion of toxins, metabolic conditions, inadequate nutrition due to poor teeth, or poor alimentary diet are conditions contributing to poor body condition. Classical and atypical scrapie is naturally occurring transmissible spongiform encephalopathies in small ruminants. The etiological agent for each one is prions. However, each of these scrapie types is epidemiologically, pathologically, and biochemically different. Though atypical scrapie occurs at low incidence, it is consistently prevalent in the small ruminant population. Hence, it is advisable to include differential diagnosis of this disease, from other possibilities, as a cause of wasting conditions detected during meat inspection at the abattoir. This manuscript is a review of the measures in force at the abattoir for scrapie control, focusing on the differential diagnosis of gross lesions related to wasting conditions detected in small ruminants during meat inspection.This article was funded by the Project POCI-01-0145-FEDER-029947 “Chronic wasting disease risk assessment in Portugal” supported by FCT (Fundação para a Ciência e a Tecnologia)- FEDER-Balcão2020, projects UIDB/04033/2020. Nuno Gonçalves-Anjo has a Ph.D. grant scholarship (reference number SFRH/BD/146961/2019) financed by FCT through FSE (Fundo Social Europeu). Also, the authors of the research unit CECAV and CITAB received funding from the FCT, under the projects UIDB/CVT/0772/2020 and UIDB/04033/2020, respectively.info:eu-repo/semantics/publishedVersio

Atypical/Nor98 Scrapie Infectivity in Sheep Peripheral Tissues

Atypical/Nor98 scrapie was first identified in 1998 in Norway. It is now considered as a worldwide disease of small ruminants and currently represents a significant part of the detected transmissible spongiform encephalopathies (TSE) cases in Europe. Atypical/Nor98 scrapie cases were reported in ARR/ARR sheep, which are highly resistant to BSE and other small ruminants TSE agents. The biology and pathogenesis of the Atypical/Nor98 scrapie agent in its natural host is still poorly understood. However, based on the absence of detectable abnormal PrP in peripheral tissues of affected individuals, human and animal exposure risk to this specific TSE agent has been considered low. In this study we demonstrate that infectivity can accumulate, even if no abnormal PrP is detectable, in lymphoid tissues, nerves, and muscles from natural and/or experimental Atypical/Nor98 scrapie cases. Evidence is provided that, in comparison to other TSE agents, samples containing Atypical/Nor98 scrapie infectivity could remain PrPSc negative. This feature will impact detection of Atypical/Nor98 scrapie cases in the field, and highlights the need to review current evaluations of the disease prevalence and potential transmissibility. Finally, an estimate is made of the infectivity loads accumulating in peripheral tissues in both Atypical/Nor98 and classical scrapie cases that currently enter the food chain. The results obtained indicate that dietary exposure risk to small ruminants TSE agents may be higher than commonly believed

Circulation of Nor98 Atypical Scrapie in Portuguese Sheep Confirmed by Transmission of Isolates into Transgenic Ovine ARQ-PrP Mice

Portugal was among the first European countries to report cases of Atypical Scrapie (ASc), the dominant form of Transmissible Spongiform Encephalopathy (TSE) in Portuguese small ruminants. Although the diagnostic phenotypes observed in Portuguese ASc cases seem identical to those described for Nor98, unequivocal identification requires TSE strain-typing using murine bioassays. In this regard, we initiated characterization of ASc isolates from sheep either homozygous for the ARQ genotype or the classical scrapie-resistant ARR genotype. Isolates from such genotypes were transmitted to TgshpXI mice expressing ovine PrPARQ. Mean incubation periods were 414 ± 58 and 483 ± 107 days in mice inoculated with AL141RQ/AF141RQ and AL141RR/AL141RR sheep isolates, respectively. Both isolates produced lesion profiles similar to French ASc Nor98 ‘discordant cases’, where vacuolation was observed in the hippocampus (G6), cerebral cortex at the thalamus (G8) level, cerebellar white matter (W1) and cerebral peduncles (W3). Immunohistochemical PrPSc deposition was observed in the hippocampus, cerebellar cortex, cerebellar white matter and cerebral peduncles in the form of aggregates and fine granules. These findings were consistent with previously reported cases of ASc Nor98 transmitted to transgenic TgshpXI mice, confirming that the ASc strain present in Portuguese sheep corresponds to ASc Nor98