Aujeszky's Disease Virus Research Articles

Ecology and Infection Dynamics of Multi-Host Amdoparvoviral and Protoparvoviral Carnivore Pathogens.

Amdoparvovirus and Protoparvovirus are monophyletic viral genera that infect carnivores. We performed surveillance for and sequence analyses of parvoviruses in mustelids in insular British Columbia to investigate parvoviral maintenance and cross-species transmission among wildlife. Overall, 19.1% (49/256) of the tested animals were parvovirus-positive. Aleutian mink disease virus (AMDV) was more prevalent in mink (41.6%, 32/77) than martens (3.1%, 4/130), feline panleukopenia virus (FPV) was more prevalent in otters (27.3%, 6/22) than mink (5.2%, 4/77) or martens (2.3%, 3/130), and canine parvovirus 2 (CPV-2) was found in one mink, one otter, and zero ermines (N = 27). Viruses were endemic and bottleneck events, founder effects, and genetic drift generated regional lineages. We identified two local closely related AMDV lineages, one CPV-2 lineage, and five FPV lineages. Highly similar viruses were identified in different hosts, demonstrating cross-species transmission. The likelihood for cross-species transmission differed among viruses and some species likely represented dead-end spillover hosts. We suggest that there are principal maintenance hosts (otters for FPV, raccoons for CPV-2/FPV, mink for AMDV) that enable viral persistence and serve as sources for other susceptible species. In this multi-host system, viral and host factors affect viral persistence and distribution, shaping parvoviral ecology and evolution, with implications for insular carnivore conservation.

Detection, genetic, and codon usage bias analyses of the VP2 gene of mink bocavirus.

Mink bocavirus 1 (MiBoV1), a novel virus detected from the feces of domestic minks in China in 2016, may be related to gastrointestinal diseases. However, its prevalence and genetic characteristics are poorly described. In this study, we examined 192 samples collected from minks in the major mink industry province from northern China. PCR results showed that 10 samples (5.2%) were positive for MiBoV1, and 60% of MiBoV1-positive samples were co-infected with Aleutian mink disease virus or mink circovirus. MiBoV1 was detected in six serum samples. Sequence analysis demonstrated that the VP2 gene of MiBoV1 was highly conserved and had low viral diversity over the VP2 region and unique nucleotide mutations. Phylogenetic analysis of the VP2 sequence demonstrated that MiBoV1 strains formed two clades and were grouped with California sea lion bocavirus, Canine bocavirus, and Feline bocavirus. Codon usage analysis revealed that most of the preferentially used codons in MiBoV1 were A- or U-ended codons, and no evident codon usage bias was found. This study provides evidence that MiBoV1 has a low prevalence in Jilin and Hebei provinces in China. Moreover, it contributes information regarding the expansion of the limited mink bocavirus sequence and determines the codon usage bias of the VP2 gene for the first time. Epidemiological surveillance is necessary to understand the importance and evolution of MiBoV1.

Molecular epidemiology of Aleutian mink disease virus causing outbreaks in mink farms from Southwestern Europe: a retrospective study from 2012 to 2019.

BackgroundAleutian mink disease virus (AMDV) causes major economic losses in fur-bearing animal production. The control of most AMDV outbreaks is complex due to the difficulties of establishing the source of infection based only on the available on-farm epidemiological data. In this sense, phylogenetic analysis of the strains present in a farm may help elucidate the origin of the infection and improve the control and biosecurity measures.ObjectivesThis study had the following aims: characterize the AMDV strains from most outbreaks produced at Spanish farms between 2012–2019 at the molecular level, and assess the utility of the combined use of molecular and epidemiological data to track the possible routes of infection.MethodsThirty-seven strains from 17 farms were partially sequenced for the NS1 and VP2 genes and analyzed phylogenetically with other strains described worldwide.ResultsSpanish AMDV strains are clustered in four major clades that generally show a good geographical correlation, confirming that most had been established in Spain a long time ago. The combined study of phylogenetic results and epidemiological information of each farm suggests that most of the AMDV outbreaks since 2012 had been produced by within-farm reservoirs, while a few of them may have been due to the introduction of the virus through international trade.ConclusionsThe combination of phylogenetic inference, together with epidemiological data, helps assess the possible origin of AMDV infections in mink farms and improving the control and prevention of this disease.

Колостральний імунітет поросят до вірусу хвороби Ауєскі за активної імунопрофілактики свиноматок

The current question of today is the formation of effective immune protection in young pigs against infectious diseases, achieved by piglets vaccination in the first weeks of their life. It is known that one of the factors influencing the quality of vaccination is colostral antibodies, which are able to deactivate the vaccine antigen. Considering this, it is important to determine the duration of colostral immunity of piglets to antigens of the Aujeszky’s disease virus during active sows immunization. For this, was formed a group of sows of 2nd-3rd gestation periods with 25 animals in each. Sows were immunized parenterally against Aujeszky’s disease with the «Adivak» vaccine at a dose of 2 ml, by mass vaccination, three times per year. The level of specific antibodies to glycoproteins E (gE) and B (gB) was determined in the blood serum of piglets before sucking colostrum and every 7 days of life until 77 days from birth by enzyme-linked immunosorbent assay (ELISA). It was revealed that before consuming colostrum, piglets did not have specific antibodies to the antigens of the Aujeszky disease virus. From 7th till 70th days of life, all piglets had specific IgG to the antigens gB and gE of the Aujeszky disease virus, and by the seventy-seventh day, 29% of the animals were seronegative. Thus, newborn piglets before colostrum suckling do not have specific immune protection against the Aujeszky disease virus against the background of sow immunization. Consumption of colostrum by piglets promotes their formation of colostral immunity, specific to the antigens of the Aujeszky disease virus. The duration of colostral antibodies’ circulation specific to the antigens of the Aujeszky disease virus in the piglets peripheral blood is 70 days. On the seventy-seventh day from birth, the level of colostral immunoglobulins decreased sharply, which contributed to the appearance of seronegative animals and an increase in their sensitivity to the action of an epizootic strain of the virus.

Mink Aleutian disease seroprevalence in China during 1981–2017: A systematic review and meta-analysis

Mink Aleutian disease (AMD) is the first of the three major diseases of fur animals. It is a common immunosuppressive disease in mink farms worldwide, which seriously endangers the development of the mink farming industry. Strengthening the understanding of the positive serum rate and spatial distribution of AMD is of great significance for the prevention and control of disease caused by the Aleutian virus. Therefore, we conducted a systematic review and meta-analysis to assess the seroprevalence of AMD in China. We extracted 45 studies related to the seroprevalence of Chinese AMD, with samples taken between 1981 and 2017. Our systematic review and meta-analysis results show that, during the selected period, the overall positive rate of AMD in China was 55.3% (95% CI 48.5–62.0). The results from subgroups analysis of the potential risk factors showed that the seroprevalence rate of AMD in China in the past 36 years rose from 48% (95% CI 37.0–60.5) in 1981–2009 to 61.4% (95% CI 43.6–79.3) in 2010–2017. The date of the spatial difference in AMD seroprevalence indicated that AMD seroprevalence was unevenly distributed in different regions: the number of mink in eastern China and northeastern China was relatively high, and the seroprevalence rates were 57.9%, (95% CI 46.2–69.7) and 61.3% (95% CI 53.1–69.5), respectively. Central China had the highest seroprevalence rate of AMD at 69.8% (95% CI 64.4–75.2). At the provincial level, the AMD seroprevalence rate in Jiangsu was as high as 96% (95% CI 94.1–97.8), and the AMD seroprevalence rate in Shaanxi was the lowest at 22.1% (95% CI 20.3–23.9). This suggested that the AMD seroprevalence rate in China was unevenly distributed. In other subgroups, the positive rate of AMD in adult mink was higher than in juvenile mink. This implied that the high prevalence of AMD in China was caused by multiple factors. The meta-regression results indicated that the detection method subgroup (P = 0.008) may be the source of heterogeneity. Our data system evaluated the prevalence of Aleutian disease in China in the last 37 years and a preliminary discussion on the risk factors of AMD. It may help prevent and control AMD in China. It is recommended to conduct further epidemiological testing and develop a comprehensive testing plan to determine the risk factors associated with Aleutian disease and improve the Aleutian disease control strategy.

Duplex PCR for Detection of Aleutian Disease Virus from Biological and Environmental Samples

Abstract Aleutian disease is one of the most serious disease entities affecting mink farms. The disease causes significant economic losses in mink breeding countries. The aim of the study was to optimize a diagnostic test based on duplex PCR to enable detection of Aleutian disease virus in biological and environmental samples. Blood (n = 40) and spleen (n = 40) samples from animals with suspected infection, and swabs from cages in which infected animals were kept (n = 20) were used for analysis. DNA was isolated from the samples, followed by optimization of the duplex PCR reaction targeting sequences coding NS1 and VP2 proteins. The qPCR method was used to determine the sensitivity of the reaction. The specificity of the analysis was confirmed by the sequencing results. Optimized duplex PCR enabled detection of Aleutian Mink Disease Virus (AMDV) genetic material in biological and environmental samples. Testing of the sensitivity of the method indicated clear amplification for both primer pairs at 102 copies of viral DNA in a reaction. Sequencing confirmed the specificity of the reaction, which in the case of both primer pairs indicated an over 90% agreement between the isolates and the variants of the virus from the databases. The use of duplex PCR to detect two regions of the AMDV genome may increase the sensitivity and specificity of the method and significantly expand the possibilities of further analysis based on sequencing.

Mucosal and systemic immune responses to Aujeszky’s disease virus (ADV) in early vaccinated piglets

Newborn humans and animals are highly susceptible to viral infections. The Aujeszky´s disease virus (ADV) is a porcine herpes virus 1 which infects the respiratory tract and is lethal during the first weeks of life. Current intramuscular vaccines, applied at weaning, induce poor mucosal immunity and frequently fail to prevent and control the disease. Additionally, early vaccination has not been studied thoroughly. Therefore, we studied a systemic/mucosal route of immunization using an inactivated ADV vaccine in two-and fourteen-day-old groups of unweaned SPF miniature Vietnamese pigs, measuring the anti ADV antibody (ELISA) and cytokine (qPCR) responses in systemic and mucosal samples. The results showed that the serum ADV-specific IgG response was higher in the 14-day groups. However, the nasal IgA responses were similar in immunized groups, although the response in saliva was higher in the 2-day old group. Moreover, in vitro ADV stimulated peripheral blood mononuclear cells and lung cells from immunized pigs showed higher IFN-γ mRNA production in the 14-day old group than in younger animals and similar levels of IL-4 and IL-10 transcripts. Our data suggest that early mucosal immunization induce humoral and cellular systemic and mucosal immune responses against ADV in young pigs and younger animals may have compensatory mechanisms to overcome early immaturity and maternal-driven immune interference. Therefore, early protection in susceptible animals could be induced using this immunization protocol, opening the possibility for its application against other viral pathogens of pigs and for traslational studies in humans.

Development and validation of nucleic acid tests to diagnose Aleutian mink disease virus

Aleutian disease (AD), caused by Aleutian mink disease virus (AMDV), causes significant welfare problems to mink, and financial losses to the farmers. As there is no vaccine or treatment available, reliable diagnostics is important for disease control. Here, we set up a probe-based real-time PCR (NS1-probe-PCR) to detect all strains of AMDV. PCR was validated and compared to two other real-time PCR methods (pan-AMDV- and pan-AMDO-PCR) currently used for AMDV diagnostics in Finland. The NS1-probe-PCR had a similar detection limit of 20 copies/reaction based on plasmid dilution series, and similar or better diagnostic sensitivity, when evaluated using spleen samples from mink, and stool samples from mink and foxes. None of the three PCR tests cross-reacted with other parvoviruses. The NS1-probe-PCR also showed a significantly higher specificity than the pan-AMDO-PCR with spleen samples and the best specificity with stool samples. Furthermore, it produced the results more rapidly than the other two PCRs making it a promising tool for both diagnostic and research purposes.

Development of an EvaGreen-based real-time PCR assay for detection of Aleutian mink disease virus

The objective of this study was to develop a rapid, sensitive and specific EvaGreen (EG)-based real-time PCR assay capable of detecting Aleutian mink disease virus (AMDV) and to evaluate the reliability of the assay for analysis of blood or tissue samples. For this assay, a pair of primers was designed based on a nonstructural protein (NS)-encoding gene of AMDV, and the identity of PCR products was identified based on a melting temperature of 82.8°C. The EG-based real-time PCR assay did not detect canine distemper virus or mink enteritis virus, and the assay could be used to detect Chinese and American AMDV strains, in contrast to a commercial TaqMan kit that could only detect American AMDV strains. The amplification efficiencies of the EG assay were 104.8% for the Chinese strain and 94.4% for the American strain, and the detection limit was 1 copy/μL of AMDV plasmid or 3 pg/μL of viral DNA (Chinese strain). The intra- and inter-assay variation coefficients of melting temperature were all lower than 0.15%, confirming the high reproducibility of the assay. Forty-five clinical blood samples were simultaneously analyzed using the EG real-time PCR, TaqMan kit and conventional PCR, and the detection rates were 91.1%, 0.0% and 86.7%, respectively. Serum samples were also collected from the corresponding blood samples and tested using the counterimmunoelectrophoresis (CIEP) assay, where positive samples accounted for 24.4% of the 45 samples. In conclusion, EG-based real-time PCR is a rapid, sensitive, universal assay that can be effectively utilized as a reliable and specific tool for detection and quantitation of AMDV.

Dynamics of Aujeszky's disease virus infection in wild boar in enzootic scenarios.

Aujeszky's disease (AD) virus is enzootic in Iberian wild boar, thus posing a threat to the official eradication of AD on extensive domestic pig farms in Spain. Understanding the dynamics and drivers of ADV infection in wild boar will help prevent viral transmission at the wild boar-pig interface. This study analyses the dynamics of ADV infection in wild boar and tests relevant hypotheses in order to identify drivers of ADV infection dynamics. Wild boar sera (N=971) and oropharyngeal tonsils (TN, N=549) collected over 11 consecutive years in south-western Spain were tested for ADV antibodies and DNA, respectively. We tested the hypotheses that population immunity modulates the risk of ADV infection (H1 ) and that detecting ADV DNA in TN is a good proxy of the annual ADV infection pressure (H2 ). This was done by building logistic regression models that were subsequently employed to test the influence of a series of host population and host individual factors-including predictors of ADV immunity in the population-on the annual risk of new ADV infections and on the presence of ADV DNA in TN. The premise of H1 was that there would be a negative association between the proportion of ADV antibody-positive wild boar in a given year and the risk of ADV infection of naïve individuals. There was, however, a positive association, and H1 was, therefore, rejected. If detecting ADV in TN had been a good indicator of ADV infection pressure, a positive association with the proportion of ADV antibody-positive wild boar would have been found. However, this was not the case and H2 was also rejected. We confirmed that ADV infection is a dynamic phenomenon. The risk of infection with ADV can change considerably between consecutive years, and these changes are positively associated with the proportion of infected wild boar in the population.

Development and evaluation of a direct TaqMan qPCR assay for the rapid detection of diverse carnivore amdoparvoviruses

Amdoparvoviruses infect carnivore species, including mink, raccoon dog, fox, skunk, and red panda. Amdoparvovirus infection is a major cause of morbidity and mortality in farmed minks. Here, we developed a direct TaqMan qPCR assay for detection and quantification of carnivore amdoparvoviruses by using three primers and one probe based on the conserved VP2 gene. The detection limit for Aleutian mink disease virus (AMDV) and Raccoon dog and arctic fox amdoparvovirus (RFAV) were 4.06 × 101 copies/μl and 2.93 × 101 copies/μl, respectively. Both intra- and inter-assay variability were less than 2%. Among 74 carnivore samples, the positive rates for amdoparvoviruses were 62.2% (46/74) by direct TaqMan qPCR, while only 40.5% (30/74) by SYBR Green I qPCR. This result suggests that the direct TaqMan qPCR was more sensitive than the SYBR Green I qPCR. Additionally, the direct TaqMan qPCR is a rapid and sensitive method for liquid samples at microliter level as the assay employed the direct alkaline lysis method to obtain viral DNA and, therefore, eliminated the cumbersome steps in extracting DNA. Overall, the direct TaqMan qPCR assay possessed high specificity, sensitivity, and reproducibility, indicating that it can be used as a powerful tool for detection and quantification of various carnivore amdoparvoviruses in epidemiological and pathogenesis studies.

Breeding parameters on a mink farm infected with Aleutian mink disease virus following the use of methisoprinol

Aleutian mink disease virus is one of the greatest threats to modern mink farming. The disease reduces fecundity and causes high mortality among kits. The aim of this study was to evaluate the effectiveness of methisoprinol in counteracting the effects of Aleutian disease, both by inhibiting replication of the virus and by mitigating the harmful effects of the disease on the fecundity and weight of infected animals. The study included 300 individuals with confirmed infection, divided according to antibody titres into three experimental groups, which received a 20% methisoprinol solution, and three control groups, which did not receive the immunostimulant. In the mink from the experimental groups, the number of copies of the genetic material of the virus in the spleens and lymph nodes was one order of magnitude lower than in the case of the control groups. Mink receiving the supplement also showed higher fecundity (on average 5.83 in the experimental groups and 4.83 in the control groups), and the weight of their offspring before slaughter was over 200 g higher. Given the lack of effective methods for immunoprophylaxis and treatment, methisoprinol supplementation can be an effective means of counteracting the effects of AMDV on persistently infected farms.

Aleutian Mink Disease Virus in the breeding environment in Poland and its place in the global epidemiology of AMDV

Aleutian mink disease (AMD) leads to an increase in mortality of animals and causes losses in mink farming. The study investigated the presence of AMDV in tissue and environmental samples from farmed mink in Poland, and selected samples were genetically characterized.Blood, spleens and swabs from the breeding environment were collected on 27 farms in seven voivodeships in Poland (n = 250). DNA was isolated, amplified by PCR and subsequently subjected to sequencing to reveal information on the molecular epidemiology of the samples. A qPCR method was used to determine the viral load in test samples.The presence of AMDV was confirmed in tissues and the farm environment on 26 of the 27 farms. The average viral load in spleens was 108 copies. The virus was also present in the blood (average - 105 copies) and the farm environment (average - 103 copies). Isolates from the West Pomeranian Voivodeship showed high similarity within the voivodeship (over 99%). Variants from the Lublin and Podlaskie Voivodeships differed 5% from any of the AMDV isolates present in the NCBI database. Isolates from the Greater Poland, Pomeranian, Podkarpackie and Lesser Poland Voivodeships formed heterogeneous clades, showing over 97% similarity to variants previously isolated in Poland, the Netherlands and Lithuania.A high degree of genetic variation was identified among the majority of the samples, which indicates that AMDV has been introduced to Poland multiple times. However, the results within one area showed high identity between isolates, suggesting that one common ancestor was the source of these outbreaks.

Endemic Skunk amdoparvovirus in free-ranging striped skunks (Mephitis mephitis) in California.

The genus Amdoparvovirus includes the newly discovered skunk amdoparvovirus and the well-characterized Aleutian disease virus which causes significant health impacts in farmed mink worldwide. In 2010-2013, an outbreak of fatal amdoparvovirus-associated disease was documented in free-ranging striped skunks (Mephitis mephitis) from the San Francisco Bay Area of California. To characterize the geographic distribution, earliest occurrence and abundance of this virus, as well as possible impacts on sympatric mustelids of conservation concern, we tested blood samples from skunks throughout California and fishers (Pekania pennanti) from northern California for amdoparvovirus DNA. Amdoparvovirus DNA was detected in 64.8% of sampled skunks (140/216), and test-positive skunks were distributed widely throughout the state, from as far north as Humboldt County and south to San Diego County. The first test-positive skunks were detected from 2004, prior to the 2010-2013 outbreak. No significant spatial or temporal clustering of infection was detected. Although healthy and clinically ill animals tested positive for amdoparvovirus DNA, histopathologic evaluation of a subset from clinically ill skunks indicated that positive PCR results were associated with pneumonia as well as there being more than one inflammatory type lesion. None of 38 fishers were PCR-positive. Given the widespread geographic distribution and lack of a clear epizootic centre, our results suggest the presence of an endemic skunk-associated amdoparvovirus strain or species. However, if the virus is not host-specific, skunks' ubiquitous presence across rural and urban habitats may pose a risk to susceptible domestic and wild species including mustelids of conservation concern such as fishers and Pacific martens (Martes caurina).

Survey of Aujeszky's Disease Virus in Hunting Dogs from Spain.

Direct contact with swine infected by Aujeszky's disease virus (ADV) represents a potential risk of transmission to carnivore species, in which the infection is normally fatal. We assessed exposure to ADV in hunting dogs in an area where the virus is highly endemic in wild boar populations. Two out of 466 (0.43%; 95% CI 0.00-1.02%) hunting dogs analyzed were positive by gE-bELISA, gB-bELISA and the virus neutralization test. The seroprevalence levels detected, as well as the absence of reports of clinical cases in the hunting dog groups tested, indicate limited contact of this species with ADV in the study area. Further studies are warranted to assess the pathogenicity of Aujeszky's disease virus strains infecting wild boar.

A comparison between intraperitoneal injection and intranasal and oral inoculation of mink with Aleutian mink disease virus

Intranasal, with (INS) and without (IN) sedation, and oral inoculation were compared with intraperitoneal (IP) injection for establishing infection with a local isolate of Aleutian mink disease virus (AMDV) in 35 American mink. Blood samples were collected on 0, 21, 36 and 56 day post-inoculation (dpi). Antiviral-antibodies and viral DNA in plasma and tissues were measured by counter-immunoelectrophoresis (CIEP) and PCR, respectively. The presence of AMDV DNA was tested by PCR in saliva, rectal and fecal samples collected on 0, 6, 10, 15, 21, 28, 36 and 56 dpi. Animals were killed at 56 dpi, samples of six organs were tested for antibody and AMDV DNA, and samples of the lungs, liver, kidneys and heart were subjected to histology. Viral DNA was detected in the spleen, lungs and lymph nodes of all inoculated mink on 56 dpi, indicating that all inoculation routes caused infection in mink. Viral DNA and antibodies were detected in plasma of all IP and INS inoculated mink by 36 dpi, but some animals which were inoculated orally or via IN remained seronegative by 56 dpi. It was concluded that INS route was the most effective method for establishing infection in mink without breaking the integrity of the animals' anatomical barriers. Viremia was short-lived in some mink, whereas antibody production persisted in seroconverted animals during the duration of the experiment. Saliva, rectal and fecal samples did not accurately detect infection. Histologic lesions of AD were observed on the four organs of most mink.

Co-circulation of highly diverse Aleutian mink disease virus strains in Finland.

Aleutian mink disease virus (AMDV) is the causative agent of Aleutian disease (AD), which affects mink of all genotypes and also infects other mustelids such as ferrets, martens and badgers. Previous studies have investigated diversity in Finnish AMDV strains, but these studies have been restricted to small parts of the virus genome, and mostly from newly infected farms and free-ranging mustelids. Here, we investigated the diversity and evolution of Finnish AMDV strains by sequencing the complete coding sequences of 31 strains from mink originating from farms differing in their virus history, as well as from free-ranging mink. The data set was supplemented with partial genomes obtained from 26 strains. The sequences demonstrate that the Finnish AMDV strains have considerable diversity, and that the virus has been introduced to Finland in multiple events. Frequent recombination events were observed, as well as variation in the evolutionary rate in different parts of the genome and between different branches of the phylogenetic tree. Mink in the wild carry viruses with high intra-host diversity and are occasionally even co-infected by two different strains, suggesting that free-ranging mink tolerate chronic infections for extended periods of time. These findings highlight the need for further sampling to understand the mechanisms playing a role in the evolution and pathogenesis of AMDV.

Serologic Survey of Selected Viral Pathogens in Free-Ranging Eurasian Brown Bears ( Ursus arctos arctos) from Slovakia.

We tested sera of 24 free-ranging European brown bears ( Ursus arctos) from six regions of Slovakia for antibodies to 10 viral agents. We tested sera by an indirect fluorescence antibody test for antibodies to canine distemper virus (CDV), canine coronavirus (CCV), canine parvovirus type 2 (CPV-2), canine adenovirus, canine parainfluenza virus type 2 (CPIV-2), and canine herpesvirus type 1 (CHV-1). We used an enzyme-linked immunosorbent assay for detection of antibodies to hepatitis E virus, bluetongue virus, West Nile virus (WNV), and Aujeszky's disease virus (ADV). We detected antibodies to CDV, CHV-1, CPV-2, CPIV-2, CCV, WNV, and ADV in seven (29%), three (12%), two (8%), two (8%), one (4%), one (4%), and one (4%) bear, respectively. Evidence of exposure of free-ranging European brown bears to CCV and ADV has not been reported.

The use of phoxim and bendiocarb for control of fleas in farmed mink (Mustela vison)

BackgroundFleas (Ceratophyllus sciurorum) are common on farmed mink in Denmark. When present, the fleas have a negative impact on the health of the farmed mink and are of nuisance for farm staff. Severe infestations of fleas cause anemia, poor growth and may result in death of mink kits. Changed behavior of the dams is also observed. Further it has been demonstrated that the fleas are vectors of Aleutian disease virus. Flea control is based on use of a few insecticides and resistance has been reported against permethrin. There is thus a need for new flea control products. In this blinded, randomized clinical trial according to GCP standard, phoxim spray and bendiocarb powder for flea control on mink farms were investigated.ResultsBoth the phoxim spray solution and bendiocarb powder were found to be efficient for the control of C. sciurorum fleas on farmed mink. Phoxim treatments reduced the number of fleas by 98.4% and the bendiocarb treatments reduced the number of fleas by 99.0% in the mink nest boxes when compared to counts in controls. No clinical signs were observed post treatment.ConclusionsThe study demonstrated that phoxim sprayed on the animals and the use of bendiocarb powder in the nest box material were highly efficient for the control of the C. sciurorum fleas on farmed mink. Both products were safe to use at the recommended dose rate. Both compounds are recommended to be integrated in a new farm management plan suggested here.

Molecular assessment of visitor personal protective equipment contamination with the Aleutian mink disease virus and porcine circovirus-2 in mink and porcine farms.

Personal protective equipment (PPE) is an element of biosecurity intended to prevent the access or spread of diseases in farms. Nevertheless, to date no extensive reports exist about the effectiveness of different available PPE on farms. Thus, our aim was to estimate the degree of protection of PPE from viral contamination during farm visits. Two farms, infected with Aleutian mink disease virus and porcine circovirus–2 respectively, were visited by six visitors wearing different combinations of PPE: coveralls with hood and bootcovers, both with a certified barrier to infective agents (certified PPE group) and non-certified bootcover and coverall without hood (non-certified PPE group). Seventy-two swab samples from PPE and both hair and street clothes under PPE were taken after the visit and analysed by qPCR. Our results reveal viral exposure during visits, and the external protections of body and shoes were contaminated in all cases (24/24). In addition, protection from viral contamination varied noticeably according to the biosecurity elements used. A higher number of positives were detected in the non-certified PPE group than in the certified PPE group, both in elements under external protections (14/18 vs 3/18) and also in hair (4/6 vs 0/6). In fact, non-certified bootcovers broke during visits, resulting in viral contamination of the internal elements under them; these are consequently not suitable for using with wrinkled surfaces usually found in farm facilities. Thus, certified coveralls should be used in order to prevent contaminations, and workers and personnel of farms should be trained in their proper use. qPCR is a useful tool in the risk management of biosecurity programmes, and our results may serve as a model to evaluate different biosecurity measures.