Previous Usutu Virus Exposure Partially Protects Magpies (Pica pica) against West Nile Virus Disease But Does Not Prevent Horizontal Transmission.

The mosquito-borne flaviviruses USUV and WNV are known to co-circulate in large parts of Europe. Both are a public health concern, and USUV has been the cause of epizootics in both wild and domestic birds, and neurological cases in humans in Europe. Here, we explore the susceptibility of magpies to experimental USUV infection, and how previous exposure to USUV would affect infection with WNV. None of the magpies exposed to USUV showed clinical signs, viremia, or detectable neutralizing antibodies. After challenge with a neurovirulent WNV strain, neither viremia, viral titer of WNV in vascular feathers, nor neutralizing antibody titers of previously USUV-exposed magpies differed significantly with respect to magpies that had not previously been exposed to USUV. However, 75% (6/8) of the USUV-exposed birds survived, while only 22.2% (2/9) of those not previously exposed to USUV survived. WNV antigen labeling by immunohistochemistry in tissues was less evident and more restricted in magpies exposed to USUV prior to challenge with WNV. Our data indicate that previous exposure to USUV partially protects magpies against a lethal challenge with WNV, while it does not prevent viremia and direct transmission, although the mechanism is unclear. These results are relevant for flavivirus ecology and contention.

Preliminary report of an outbreak of SARS-CoV-2 in mink and mink farmers associated with community spread, Denmark, June to November 2020.

In June-November 2020, SARS-CoV-2-infected mink were detected in 290 of 1,147 Danish mink farms. In North Denmark Region, 30% (324/1,092) of people found connected to mink farms tested SARS-CoV-2-PCR-positive and approximately 27% (95% confidence interval (CI): 25-30) of SARS-CoV-2-strains from humans in the community were mink-associated. Measures proved insufficient to mitigate spread. On 4 November, the government ordered culling of all Danish mink. Farmed mink constitute a potential virus reservoir challenging pandemic control.

[Ocular thelaziosis in a dog in Germany - an autochthonous case?] / Okuläre Thelaziose bei einem Hund in Deutschland ­ ein autochthoner Fall?

Thelazia callipaeda is a vector-borne nematode transmitted by Phortica spp. (fruit flies) and one of the causes of mild to severe conjunctivitis and keratitis in dogs, cats, rabbits and humans. It has been formerly known as the oriental eye worm based on its geographic occurrence. By now, it has been shown to be endemic in several southern and eastern European countries as well as extending its geographic distribution further throughout Europe. In the present case report, T. callipaeda infection was diagnosed in a female dog from Germany. The dog was referred by a local veterinarian due to a treatment-resistant conjunctivitis. A comprehensive ophthalmologic examination revealed 3 adult eye worms in the conjunctival sac as well as on the bulbar side of the nictitating membrane of the left eye. These were identified by morphological features and molecular techniques as T. callipaeda and represented the primary cause of the dog's unilateral blepharospasm, hyperemic conjunctiva and epiphora. Treatment consisted of manual collection of the adult worms and the administration of moxidectin/imidacloprid as spot on (Advocate®, Bayer). All clinical signs resolved within one week after treatment. In Germany, ocular thelaziosis still represents a rare disease. Usually, it is diagnosed in cats and dogs either imported from abroad or accompanying the owners on holiday travels to endemic countries. The dog presented in this case report was born in Germany. Except for a one-week stay in the Netherlands 11 months before the symptoms began, it had never traveled abroad. Considering the prepatency of T. callipaeda, an autochthonous transmission in this case is highly probable.

Animal movement in a pastoralist population in the Maasai Mara Ecosystem in Kenya and implications for pathogen spread and control.

Livestock movements are important drivers for infectious disease transmission. However, paucity of such data in pastoralist communities in rangeland ecosystems limits our understanding of their dynamics and hampers disease surveillance and control. The aim of this study was to investigate animal movement networks in a pastoralist community in Kenya, and assess network-based strategies for disease control. We used network analysis to characterize five types of between-village animal movement networks. We then evaluated implications of these networks for disease spread and control by quantifying topological changes in the network associated with targeted and random removal of nodes. To construct these networks, data were collected using standardized questionnaires (N = 165 households) from communities living within the Maasai Mara Ecosystem in southwestern Kenya. Our analyses show that the Maasai Mara National Reserve (MMNR), a protected wildlife area, was critical for maintaining village connectivity in the agistment network (dry season grazing), with MMNR-adjacent villages being highly utilized during the dry season. In terms of disease dynamics, the network-based basic reproduction number, R0, was sufficient to allow disease invasion in all the five networks, and removal of villages based on degree or betweenness was not efficient in reducing R0. However, we show that villages with high degree or betweenness may play an important role in maintaining network connectivity, which may not be captured by assessment of R0 alone. Such villages may function as potential "firebreaks." For example, targeted removal of highly connected village nodes was more effective at fragmenting each network than random removal of nodes, indicating that network-based targeting of interventions such as vaccination could potentially disrupt transmission pathways in the ecosystem. In conclusion, this work shows that animal movements have the potential to shape patterns of disease transmission in this ecosystem, with targeted interventions being a practical and efficient measure for disease control.

Modelling transmission and control of Mycobacterium avium subspecies paratuberculosis within Irish dairy herds with compact spring calving.

Paratuberculosis is a chronic bacterial infection of the intestine in cattle caused by Mycobacterium avium subspecies paratuberculosis (Map). To better understand Map transmission in Irish dairy herds, we adapted the French stochastic individual-based epidemiological simulation model to account for seasonal herd demographics. We investigated the probability of Map persistence over time, the within-herd prevalence over time, and the relative importance of transmission pathways, and assessed the relative effectiveness of test-and-cull control strategies. We investigated the impact on model outputs of calf separation from cows (calves grazed on pasture adjacent to cows vs. were completely separated from cows) and test-and-cull. Test-and-cull scenarios consisted of highly test-positive cows culled within 13 or 4 weeks after detection, and calf born to highly test-positive cows kept vs removed. We simulated a typical Irish dairy herd with on average 82 lactating cows, 112 animals in total. Each scenario was iterated 1000 times to adjust variation caused by stochasticity. Map was introduced in the fully naive herd through the purchase of a moderately infectious primiparous cow. Infection was considered to persist when at least one infected animal remained in the herd or when Map was present in the environment. The probability of Map persistence 15 years after introduction ranged between 32.2-42.7 % when calves and cows had contact on pasture, and between 18.9-29.4 % when calves and cows were separated on pasture. The most effective control strategy was to cull highly test-positive cows within four weeks of detection (absolute 10 % lower persistence compared to scenarios without control). Removing the offspring of highly test-positive dams did not affect either Map persistence or within-herd prevalence of Map. Mean prevalence 15 years after Map introduction was highest (63.5 %) when calves and cows had contact on pasture. Mean prevalence was 15 % lower (absolute decrease) when cows were culled within 13 weeks of a high test-positive result, and 28 % lower when culled within 4 weeks. Around calving, the infection rate was high, with calves being infected in utero or via the general indoor environment (most important transmission routes). For the remainder of the year, the incidence rate was relatively low with most calves being infected on pasture when in contact with cows. Testing and culling was an effective control strategy when it was used prior to the calving period to minimize the number of highly infectious cows present when calves were born.

SARS-CoV-2 Transmission between Mink (Neovison vison) and Humans, Denmark.

Severe acute respiratory syndrome coronavirus 2 has caused a pandemic in humans. Farmed mink (Neovison vison) are also susceptible. In Denmark, this virus has spread rapidly among farmed mink, resulting in some respiratory disease. Full-length virus genome sequencing revealed novel virus variants in mink. These variants subsequently appeared within the local human community.

Research Note: Horizontal transmission and internal organ colonization by Salmonella Enteritidis and Salmonella Kentucky in experimentally infected laying hens in indoor cage-free housing.

The transmission of Salmonella to humans via contaminated eggs is an international public health concern. S. Enteritidis is deposited inside eggs after colonizing reproductive tissues of infected hens. Diverse housing facility characteristics and flock management practices influence Salmonella persistence and transmission in poultry, but the food safety consequences of different housing systems for laying hens remain unresolved. The present study compared the horizontal transmission of infection and invasion of internal organs during the first 2 wk after experimental S. Enteritidis and S. Kentucky infection of laying hens in indoor cage-free housing. Groups of 72 hens were housed in isolation rooms simulating commercial cage-free barns, and 1/3 of the hens in each room were orally inoculated with either S. Enteritidis (2 rooms) or S. Kentucky (2 rooms). At 6 d and 12 d postinoculation, 12 inoculated and 24 contact-exposed hens in each room were euthanized, and samples of liver, spleen, ovary, oviduct, and intestinal tract were removed for bacteriologic culturing. All orally inoculated hens were positive for intestinal colonization by S. Enteritidis at 6 d postinfection, and 70.8% of contact-exposed hens had become colonized by 12 d. S. Enteritidis was isolated from 100% of livers and 50.0% of ovaries from inoculated birds at 6 d and from 41.7% of livers and 10.4% of ovaries from contact-exposed birds at 12 d. The majority of both orally inoculated and contact-exposed hens were positive for intestinal colonization by S. Kentucky at 6 d, but S. Kentucky was found in other internal organs of both inoculated and contact-exposed hens significantly (P < 0.05) less often than S. Enteritidis at both sampling intervals. These results indicate that Salmonella infection can spread rapidly and extensively among hens in cage-free indoor housing, including a high frequency of internal organ involvement for invasive S. Enteritidis.

Evidence of Zika virus horizontal and vertical transmission in Aedes albopictus from Spain but not infectious virus in saliva of the progeny.

Aedes albopictus mosquitoes have been experimentally demonstrated to be a competent vector for Zika virus (ZIKV) in different countries, but there are still some gaps related to the importance of Ae. albopictus in ZIKV transmission. Recent studies on Spanish Ae. albopictus populations showed controversial results for ZIKV transmission and no studies have been performed yet to detect infectious ZIKV in saliva of progeny of infected female mosquitoes. Herein, the horizontal transmission (HT) and vertical transmission (VT) of ZIKV in field-collected Ae. albopictus mosquitoes from Spain were evaluated for ZIKV strains (African I and Asian lineages) to better estimate the risk of ZIKV transmission by Ae. albopictus. The two field-collected Ae. albopictus populations assayed were infected by all tested ZIKV strains, however differences in terms of vector competence were detected depending on strain-population combination. Moreover, a higher susceptibility to the African I lineage strain than to the Asian lineage strain was observed in both mosquito populations. On the other hand, VT was demonstrated for both ZIKV lineages, detecting the virus in both males and females of the progeny of infected females, although importantly ZIKV dissemination and transmission were not detected in the infected females from the offspring. The results of the present study demonstrate that Spanish Ae. albopictus populations could sustain virus transmission in case of ZIKV introduction, but VT would play a poor role in the ZIKV epidemiology. Overall, our results provide helpful information to health authorities to establish efficient surveillance and vector control programmes for ZIKV.

The role of animals as a source of antimicrobial resistant nontyphoidal Salmonella causing invasive and non-invasive human disease in Vietnam.

BACKGROUND: Nontyphoidal Salmonella (NTS) are associated with both diarrhea and bacteremia. Antimicrobial resistance (AMR) is common in NTS in low-middle income countries, but the major source(s) of AMR NTS in humans are not known. Here, we aimed to assess the role of animals as a source of AMR in human NTS infections in Vietnam. We retrospectively combined and analyzed 672 NTS human and animal isolates from four studies in southern Vietnam and compared serovars, sequence types (ST), and AMR profiles. We generated a population structure of circulating organisms and aimed to attribute sources of AMR in NTS causing invasive and noninvasive disease in humans using Bayesian multinomial mixture models. RESULTS: Among 672 NTS isolates, 148 (22%) originated from human blood, 211 (31%) from human stool, and 313 (47%) from animal stool. The distribution of serovars, STs, and AMR profiles differed among sources; serovars Enteritidis, Typhimurium, and Weltevreden were the most common in human blood, human stool, and animals, respectively. We identified an association between the source of NTS and AMR profile; the majority of AMR isolates were isolated from human blood (p < 0.001). Modelling by ST-AMR profile found chickens and pigs were likely the major sources of AMR NTS in human blood and stool, respectively; but unsampled sources were found to be a major contributor. CONCLUSIONS: Antimicrobial use in food animals is hypothesized to play role in the emergence of AMR in human pathogens. Our cross-sectional population-based approach suggests a significant overlap between AMR in NTS in animals and humans, but animal NTS does explain the full extent of AMR in human NTS infections in Vietnam.

Evolutionary dynamics and transmission patterns of Newcastle disease virus in China through Bayesian phylogeographical analysis.

The Chinese poultry industry has experienced outbreaks of Newcastle disease (ND) dating back to the 1920s. However, the epidemic has exhibited a downtrend in recent years. In this study, both observational and genetic data [fusion (F) and haemagglutinin-neuraminidase genes (HN)] were analyzed, and phylogeographic analysis based on prevalent genotypes of Newcastle disease virus (NDV) was conducted for better understanding of the evolution and spatiotemporal dynamics of ND in China. In line with the observed trend of epidemic outbreaks, the effective population size of F and HN genes of circulating NDV is no longer growing since 2000, which is supported by 95% highest posterior diversity (HPD) intervals. Phylogeographic analysis indicated that the two eastern coastal provinces, Shandong and Jiangsu were the most relevant hubs for NDV migration, and the geographical regions with active NDV diffusion seemed to be constrained to southern and eastern China. The live poultry trade may play an important role in viral spread. Interestingly, no migration links from wild birds to poultry received Bayes factor support (BF > 3), while the migration links from poultry to wild birds accounted for 64% in all effective migrations. This may indicate that the sporadic cases of ND in wild bird likely spillover events from poultry. These findings contribute to predictive models of NDV transmission, and potentially help in the prevention of future outbreaks.

Fauna flebotomínica e soroprevalência para leishmaniose visceral canina em área urbana na região Centro-Oeste do Brasil / [Phlebotomine fauna and seroprevalence for canine visceral leishmaniasis in urban area from Central-West region of Brazil]

A leishmaniose visceral americana (LVA) é uma zoonose de transmissão vetorial na qual o cão tem papel importante na epidemiologia da doença. No Brasil, a elevada prevalência da infecção em cães está diretamente correlacionada com o aumento no risco de ocorrência de casos de LVA. O objetivo deste estudo foi investigar a fauna flebotomínica e verificar a soroprevalência da leishmaniose visceral canina (LVC) na localidade Pedra 90, no município de Cuiabá. Para o levantamento entomológico, armadilhas CDC foram utilizadas de agosto de 2014 a julho de 2015. Na avaliação sorológica dos cães, o teste imunocromatográfico DPP LVC foi utilizado para a triagem das amostras, enquanto o ensaio imunoenzimático (EIE) para o diagnóstico da LVC (Bio-Manguinhos) foi empregado como teste confirmatório. O trabalho vem acrescentar à fauna flebotomínica do município de Cuiabá as espécies Lu. andersoni, Lu. braziliensis, Lu. bourrouli e Lu. scaffi, não registradas em publicações anteriores. Além disso, entre as espécies de flebotomíneos com importância médica, Lu. cruzi, Lu. flaviscutellata e Lu. whitmani foram capturadas. No inquérito canino, a prevalência de LVC observada na localidade Pedra 90 foi de 1,14%, indicando que a região pode ser considerada como área de transmissão.(AU)

American visceral leishmaniasis (AVL) is a vector-borne zoonosis in which the dog has an important role in the epidemiology of the disease. In Brazil, a high prevalence of canine infection is directly correlated with an increased risk of occurrence of AVL. The aim of this study was to investigate the phlebotomine fauna and seroprevalence of canine visceral leishmaniasis in Pedra 90 region of Cuiabá municipality. For the entomological survey, CDC traps were used from August 2014 to July 2015. In the serological evaluation of dogs, the immunochromatographic test DPP LVC was employed for screening the samples while enzyme-linked immunosorbent assay (Bio-Manguinhos) was used as a confirmatory assay. The previously unreported phlebotomine species Lu. andersoni, Lu. braziliensis, Lu. bourrouli, and Lu. scaffi were added to the phlebotomine fauna of Cuiabá. In addition, the medically important phlebotomine species Lu. cruzi, Lu. flaviscutellata, and Lu. whitmani were identified. The canine survey revealed the prevalence of 1.14% for canine visceral leishmaniasis in the Pedra 90 region, the region being considered a transmission area.(AU)

Role of three tick species in the maintenance and transmission of Severe Fever with Thrombocytopenia Syndrome Virus.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel phlebovirus in the Bunyaviridae family, causing SFTS with high mortality rate. Haemaphysalis longicornis ticks has been demonstrated as a competent vector of SFTSV by experimental transmission study and field study. However, there has been query whether other tick species that infest human beings in the SFTS endemic regions are capable of transmitting the pathogen. Here by performing experimental transmission study, we compared the capable of transmitting SFTSV among Ixodes sinensis, Ixodes persulcatus and Dermacentor silvarum ticks. The transovarial transmission was seen in the I. sinensis ticks with a rate of 40%, but neither in I. persulcatus nor in D. silvarum ticks. I. sinensis ticks also have the ability to transmit SFTSV horizontally to uninfected mice at 7 days after feeding, but not for I. persalcatus or D. silvarum ticks. In the transstadial transmission of I. persulcatus and D. silvarum ticks, I. persulcatus ticks were tested negative from larvae to adults. But the D. silvarum ticks were tested positive from larvae to nymphs, with the positive rate of 100% (10/10) for engorged larval ticks and 81.25% (13/16) for molted nymphs. However, the mice bitten by SFTSV-infected D. silvarum nymphs were negative for SFTSV detection. Therefore, there is not enough evidence to prove the transstadial transmission of SFTSV in I. persalcatus and D. silvarum ticks.

Honey bee virus causes context-dependent changes in host social behavior.

Anthropogenic changes create evolutionarily novel environments that present opportunities for emerging diseases, potentially changing the balance between host and pathogen. Honey bees provide essential pollination services, but intensification and globalization of honey bee management has coincided with increased pathogen pressure, primarily due to a parasitic mite/virus complex. Here, we investigated how honey bee individual and group phenotypes are altered by a virus of concern, Israeli acute paralysis virus (IAPV). Using automated and manual behavioral monitoring of IAPV-inoculated individuals, we find evidence for pathogen manipulation of worker behavior by IAPV, and reveal that this effect depends on social context; that is, within versus between colony interactions. Experimental inoculation reduced social contacts between honey bee colony members, suggesting an adaptive host social immune response to diminish transmission. Parallel analyses with double-stranded RNA (dsRNA)-immunostimulated bees revealed these behaviors are part of a generalized social immune defensive response. Conversely, inoculated bees presented to groups of bees from other colonies experienced reduced aggression compared with dsRNA-immunostimulated bees, facilitating entry into susceptible colonies. This reduction was associated with a shift in cuticular hydrocarbons, the chemical signatures used by bees to discriminate colony members from intruders. These responses were specific to IAPV infection, suggestive of pathogen manipulation of the host. Emerging bee pathogens may thus shape host phenotypes to increase transmission, a strategy especially well-suited to the unnaturally high colony densities of modern apiculture. These findings demonstrate how anthropogenic changes could affect arms races between human-managed hosts and their pathogens to potentially affect global food security.

The impact of changing farm structure on foot-and-mouth disease spread and control: A simulation study.

Foot-and-mouth disease (FMD) is a highly contagious viral disease that affects ruminants and pigs. Countries with large exports of livestock products are highly vulnerable to economic damage following an FMD incursion. The faster disease spread is controlled, the lower the economic damage. During the past decades, the structure of livestock production has dramatically changed. To maintain the relevance of contingency plans, it is important to understand the effects of changes in herd structure on the spread and control of infectious diseases. In this study, we compare the spread and control of FMD based on 2006/2007 and 2018 livestock data. Spread of FMD in Denmark was simulated using the DTU-DADS model, applying different control measures. The number of cattle, swine and sheep/goat herds reduced from about 50,000 in total in 2006/2007 to about 33,000 in 2018. During this period, the average number of outgoing animal movements and the exports of swine and swine products increased by about 35% and 22%, respectively. This coincided with an overall increase in herd size of 14%. Using the EU and national control measures (Basic: 3 days standstill, depopulation of detected herds followed by cleaning and disinfection and establishment of control zones, where tracing, surveillance and contact restrictions are implemented), we found that the simulated epidemics in 2018 would be about 50% shorter in duration, affect about 50% fewer herds but cause more economic damage, compared to epidemics using 2006/2007 data. When 2006/2007 data were used, Basic + pre-emptive depopulation (Depop) overall was the optimal control strategy. When 2018 data were used, this was the case only when epidemics were initiated in cattle herds, whereas when epidemics were initiated in sow or sheep/goats herds, basic performed as well as Depop. The results demonstrate that regular assessment of measures to control the spread of infectious diseases is necessary for contingency planning.

High proportion of cattle and sheep seropositive and renal carriers of Leptospira sp. under semiarid conditions / Alta proporção de bovinos e ovinos soropositivos e portadores renais de Leptospira sp. em condições semiáridas

The aims of this study were to perform serological and molecular detection of Leptospira sp. infection in cattle and sheep under semiarid conditions. Based on a preliminary study performed in our research group, we selected six rural properties showing a positivity ≥ 60% for Sejroe serogroup with titer ≥ 200 measured in serological tests from cattle. In the present study, blood and urine samples were collected from 99 females of reproductive age (51 cattle and 48 sheep) for serological diagnosis, molecular detection and Leptospira sp. attempt to strain recovery. Of the 99 analyzed animals 38.4% (38/99) were positively reactive at the serological tests. Of them, 49% (25/51) were cattle and 27.1% (13/48) sheep. The serogroups detected in cattle were Sejroe (36.8%), Hebdomadis (26.3%), Australis (10.5%), Djasiman (10.5%), Ballum (5.3%), Pomona (5.3%), and Cynopteri (5.3%) with titers of 100­800. In sheep, the reactive serogroups were Australis (27.3%), Ballum (27.3%), Djasiman (18.1%), Tarassovi (9.1%), Icterohaemorrhagiae (9.1%), and Cynopteri (9.1%) with titers of 100­400.Leptospiral DNA was detected in nine urine samples, including five cattle and four sheep. Property 1 showed the highest serological positivity frequencies for both cattle (70.6%) and sheep (70.6%). Similarly, the highest frequency of DNA detection was also found (eight samples, 89%). In this property, we observed the existence of consorted rearing of cattle and sheep with close coexistence between these species. In semiarid conditions, transmission among animals of the same species seems to be the main form of Leptospira sp. dissemination in cattle and sheep herds. However, the contribution of other domestic and wild animals cannot be discarded. The practice of consorted rearing of cattle and sheep and their close coexistence may facilitate the spread of the pathogen in rural properties.

Os objetivos deste estudo foram realizar detecção sorológica e molecular da infecção por Leptospira sp. em bovinos e ovinos em condições semiáridas. Com base em estudo preliminar realizado em nosso grupo de pesquisa, foram selecionadas seis propriedades rurais com soropositividade ≥ 60% para o sorogrupo Sejroe com título ≥ 200 em bovinos. No presente estudo, amostras de sangue e urina foram coletadas de 99 fêmeas em idade reprodutiva (51 bovinos e 48 ovinos) para diagnóstico sorológico, detecção molecular e tentativa de recuperação de estirpesde Leptospira sp. Dos 99 animais analisados, 38,4% (38/99) foram sororeativos nos testes sorológicos. Destes, 49% (25/51) eram bovinos e 27,1% (13/48) ovinos. Os sorogrupos detectados em bovinos foram Sejroe (36,8%), Hebdomadis (26,3%), Australis (10,5%), Djasiman (10,5%), Ballum (5,3%), Pomona (5,3%) e Cynopteri (5,3%) com títulos de 100 a 800. Nos ovinos, os sorogrupos reativos foram Australis (27,3%), Ballum (27,3%), Djasiman (18,1%), Tarassovi (9,1%), Icterohaemorrhagiae (9,1%) e Cynopteri (9,1%) com títulos de 100-400. O DNA leptospiral foi detectado em nove amostras de urina, incluindo cinco bovinos e quatro ovinos. A propriedade 1 apresentou as maiores frequências de positividade sorológica para bovinos (70,6%) e ovinos (70,6%). Da mesma forma, a maior frequência de detecção de DNA também foi encontrada (oito amostras, 89%). Nesta propriedade observou-se a existência de criação consorciada de bovinos e ovinos com estreita convivência entre estas espécies. Em condições semiáridas, a transmissão entre animais da mesma espécie parece ser a principal forma de disseminação de Leptospira sp. em rebanhos bovinos e ovinos. No entanto, a contribuição de outros animais domésticos e selvagens não pode ser descartada. A prática de criação consorciada de bovinos e ovinos e sua estreita convivência podem facilitar a disseminação do patógeno em propriedades rurais.

Inhibition of a novel coumarin on an aquatic rhabdovirus by targeting the early stage of viral infection demonstrates potential application in aquaculture.

Spring viremia of carp virus (SVCV) is one of the most serious pathogens in aquaculture, resulting in devastating damage in cyprinid. In this study, we designed and synthesized a novel coumarin derivative (C3007) for evaluating its in vitro and in vivo anti-SVCV effects. Here, we determined that up to 25 mg/L C3007 significantly decreased SVCV protein gene expression levels in EPC cells by a maximum inhibitory rate of >95%. When C3007 was preincubated with SVCV, infectivity was significantly inhibited in vitro in a time-dependent manner, with complete inhibition at 25 mg/L. For in vivo studies, C3007 exhibited an anti-SVCV effect by substantially enhancing the survival rate of virus-infected fish via intraperitoneal injection. Although the horizontal transmission of SVCV was hindered by C3007 in a static cohabitation challenge model, it was not completely blocked, showing that the viral loads in recipient fish were obviously reduced. Thus, C3007 could potentially be used as a therapeutic agent with great potential in aquatic systems and may also be suitable for applications in pond aquaculture settings against viral transmission. Additionally, the C3007-preincubated virus induced an antiviral immune response with high levels of IFN expression, suggesting that C3007 pre-treatment could be used in vaccine development.

Prevention of transmission of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum by Ixodes spp. ticks to dogs treated with the Seresto® collar (imidacloprid 10% + flumethrin 4.5%).

The capability of imidacloprid 10% + flumethrin 4.5% (Seresto®) collars to prevent transmission of Borrelia burgdorferi sensu lato (Bbsl) and Anaplasma phagocytophilum (Ap) by naturally infected ticks was evaluated in two studies with 44 dogs. In each study, one group served as non-treated control, whereas the other groups were treated with the Seresto® collar. All dogs were exposed to naturally Bbsl- and Ap-infected hard ticks (Ixodes ricinus, Ixodes scapularis). In study 1, tick infestation was performed on study day (SD) 63 (2 months post-treatment [p.t.]); in study 2, it was performed on SD 32 (one month p.t.) respectively SD 219 (seven months p.t.). In situ tick counts were performed 2 days after infestation. Tick counts and removals followed 6 (study 1) or 5 days (study 2) later. Blood sampling was performed for the detection of specific Bbsl and Ap antibodies and, in study 1, for the documentation of Ap DNA by PCR. Skin biopsies were examined for Bbsl by PCR and culture (only study 1). The efficacy against Ixodes spp. was 100% at all time points. In study 1, two of six non-treated dogs became infected with Bbsl, and four of six tested positive for Ap; none of the treated dogs tested positive for Bbsl or Ap. In study 2, ten of ten non-treated dogs became infected with Bbsl and Ap; none of the treated dogs tested positive for Bbsl or Ap; 100% acaricidal efficacy was shown in both studies. Transmission of Bbsl and Ap was successfully blocked for up to 7 months.

Aerosol Detection and Transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): What Is the Evidence, and What Are the Knowledge Gaps?

In human and veterinary medicine, there have been multiple reports of pathogens being airborne under experimental and field conditions, highlighting the importance of this transmission route. These studies shed light on different aspects related to airborne transmission such as the capability of pathogens becoming airborne, the ability of pathogens to remain infectious while airborne, the role played by environmental conditions in pathogen dissemination, and pathogen strain as an interfering factor in airborne transmission. Data showing that airborne pathogens originating from an infectious individual or population can infect susceptible hosts are scarce, especially under field conditions. Furthermore, even though disease outbreak investigations have generated important information identifying potential ports of entry of pathogens into populations, these investigations do not necessarily yield clear answers on mechanisms by which pathogens have been introduced into populations. In swine, the aerosol transmission route gained popularity during the late 1990's as suspicions of airborne transmission of porcine reproductive and respiratory syndrome virus (PRRSV) were growing. Several studies were conducted within the last 15 years contributing to the understanding of this transmission route; however, questions still remain. This paper reviews the current knowledge and identifies knowledge gaps related to PRRSV airborne transmission.

Hunting practices in northern Australia and their implication for disease transmission between community dogs and wild dogs.

OBJECTIVE: This survey aimed to understand hunting practices involving domestic dogs in remote Indigenous communities in northern Australia and, in the context of disease transmission, describe the domestic-wild dog interface and intercommunity interactions of hunting dogs during hunting activities. METHODS: A cross-sectional survey of 13 hunters from communities of the Northern Peninsula Area (NPA) of Queensland gathered information on demographics of hunters and hunting dogs, hunting practices and past encounters with wild dogs during hunting trips. Social networks that described the connections of hunters between NPA communities from hunting expeditions were developed. RESULTS: Most hunters interviewed were not aware of any diseases that could be transmitted to dogs (n = 11) or humans (n = 9) from wild animals while hunting. More than half (n = 7) of the respondents had experienced at least one wild dog encounter during hunting in the year prior to the interview. A map of the relative risk of interactions between wild and hunting dogs during hunting trips allowed the identification of high-risk areas in the NPA; these areas are characterised by dense rainforests. The social networks at the community level resulted in relatively large density measures reflecting a high level of intercommunity connectedness. CONCLUSIONS: This study contributes to our knowledge of Australian Indigenous hunting practices and supports the potential for disease transmission at the domestic-wild dog interface and intercommunity level through contacts between hunting dogs during hunting activities. Insights from this study also highlight the need for educational programs on disease management in Indigenous communities of northern Australia.

Commercial vaccine against pseudorabies virus: A hidden health risk for dogs.

Pseudorabies virus (PRV) is considered as an infectious agent with a wide of host range, causing considerable economic losses in animal husbandry. Although the commercial vaccine against PRV plays an critical role in control of this disease in swine industry, the potential risk of commercial vaccines against PRV for other host is unclear. Here, we report that the commercial vaccine against PRV is a hidden health risk for dogs. We found that different attenuated PRV strains in commercial vaccines possess different tissue tropism, and that the attenuated PRV strains are lethal to dogs, and that the attenuated PRV strain possesses the ability to spread horizontally among the dogs. Collectively, our findings provide clues that the commercial vaccine against PRV is a hidden risk for dogs, even for the owner of pet dogs to take seriously.