Severe Fever with Thrombocytopenia Syndrome in Cats and Its Prevalence among Veterinarian Staff Members in Nagasaki, Japan

In this study, we investigated severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) infection in cats in Nagasaki, Japan. In total, 44 of 133 (33.1%) cats with suspected SFTS were confirmed to be infected with SFTSV. Phylogenetic analyses of SFTSV isolates from cats indicated that the main genotype in Nagasaki was J1 and that unique reassortant strains with J2 (S segment) and unclassified genotypes (M and L segments) were also present. There were no significant differences in virus growth in cell cultures or fatality in SFTSV-infected mice between the SFTSV strains that were isolated from recovered and fatal cat cases. Remarkably, SFTSV RNAs were detected in the swabs from cats, indicating that the body fluids contain SFTSV. To evaluate the risk of SFTSV infection when providing animal care, we further examined the seroprevalence of SFTSV infection in veterinarian staff members; 3 of 71 (4.2%) were seropositive for SFTSV-specific antibodies. Our results provide useful information on the possibility of using cats as sentinel animals and raised concerns of the zoonotic risk of catching SFTSV from animals.

Comparison of Three Serological Methods for the Epidemiological Investigation of TBE in Dogs

Tick-borne encephalitis (TBE) virus is an emerging pathogen that causes severe infections in humans. Infection risk areas are mostly defined based on the incidence of human cases, a method which does not work well in areas with sporadic TBE cases. Thus, sentinel animals may help to better estimate the existing risk. Serological tests should be thoroughly evaluated for this purpose. Here, we tested three test formats to assess the use of dogs as sentinel animals. A total of 208 dog sera from a known endemic area in Southern Germany were tested in an All-Species-ELISA and indirect immunofluorescence assays (IIFA), according to the manufacturer’s instructions. Sensitivity and specificity for both were determined in comparison to the micro-neutralization test (NT) results. Of all 208 samples, 22.1% tested positive in the micro-NT. A total of 18.3% of the samples showed characteristic fluorescence in the IIFA and were, thus, judged positive. In comparison to the micro-NT, a sensitivity of 78.3% and a specificity of 98.8% was obtained. In the ELISA, 19.2% of samples tested positive, with a sensitivity of 84.8% and a specificity of 99.4%. The ELISA is a highly specific test for TBE-antibody detection in dogs and should be well suited for acute diagnostics. However, due to deficits in sensitivity, it cannot replace the NT, at least for epidemiological studies. With even lower specificity and sensitivity, the same applies to IIFA.

Antibody Titers and Seroconversion Kinetics of Outbred Swiss and Heterozygous Nude Soiled-bedding Sentinels for Murine Norovirus and Mouse Hepatitis Virus

Sentinel animals remain a common means of evaluating rodent health in research colonies. An evaluation of our sentinelprogram revealed that using Crl:CD1(ICR)-Elite (CD1-E) mice was expensive, occasionally disrupted by limited supply, andminimally responsive to the 3Rs. This evaluation prompted us to explore the use of CRL:NU-Foxn1nu/+ (Het-nude) mice assoiled-bedding sentinel (SBS) animals. Het-nude mice are a byproduct of breeding outbred athymic nude mice and are reared in isolators, with similar health status as CD1-E. Het-nude mice have a thymus, but may have smaller thymic size and fewer bone marrow stem cells than do wildtype controls, suggesting that Het-nude mice might not be immunologically normal.This study compared the antibody titer and seroconversion kinetics of Het-nude and CD1-E SBS to murine norovirus (MNV)and mouse hepatitis virus (MHV). Het-nude and CD1-E female SBS (n = 22 mice of each stock) were housed continuously on soiled bedding collected from MNV-positive or MNV- and MHV-positive colonies at cage changes. Blood was collected for serology at 3, 9 and 12 to 19 wk after the start of soiled bedding exposure. Antibody titers to MNV or MHV did not differ significantly between Het-nude and CD1-E mice. A significant relationship was found between weeks of exposure and titer levels with an increase in titer over the testing period. This study supports the possible use of Het-nude mice as SBS, giventhat their antibody responses to MNV and MHV are equivalent to those of CD1-E mice.

Epidemiologic significance of Toxoplasma gondii infections in chickens (Gallus domesticus): the past decade

Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.

Seroprevalence and incidence of Leptospira spp. in domestic dogs in the Southeast region of São Paulo State, Brazil

ABSTRACT: Leptospirosis is a zoonotic disease caused by Leptospira and domestic dogs can act as host of some serovars. In order to analyze the transmission dynamics in a dog population, with and without immunization, a longitudinal study was carried out with a focus to evaluate antibody response and to identify serovars. Blood samples were collected in three consecutive years (2015 to 2017) from 331, 373 and 347 dogs respectively. The dog seroprevalence in each year was 11%, 7% and 14%, respectively, and the incidence in 2016 was 5% and in 2017, 14%. The most frequent serovars were Cynopteri and Butembo in 2015, Cynopteri, Butembo and Hardjoprajitno in 2016, and Canicola and Butembo in 2017. Dogs can play a role as sentinel animals and hosts of Leptospira serovars. The percentage of seropositive dogs due to vaccination was higher than the previous years without immunization and lower than in previous years for other serovars, which we interpret as evidence for the importance of immunization. These parameters associated with active canine population control are important for prevention and control of leptospirosis not only in dogs but alsoto inhibit the transmission between dogs and humans.

Seroconversion of 1-year-old Mice to Murine Norovirus

Rodent sentinel screening for adventitious pathogens is an integral part of many biomedical research institutes and universities that use rodents in research. Typical screening programs involving live sentinel animals typically purchase young SPF sentinel animals that are sampled and replaced quarterly. Previous reports suggest that mice as old as 6 mo are effective sentinels for various agents. In efforts to reduce the number of animals used in our sentinel program, we wanted to investigate the possibility of keeping sentinel animals inhouse for 12 mo at a time. We exposed mice (age, 40 to 48 wk) to murine norovirus (MNV) to test whether they could reliably produce detectable levels of antibodies (similar to younger mice) to this adventitious pathogen. Mice first exposed to MNV at 40 to 48 wk of age seroconverted to MNV after both direct inoculation (through gavage) and indirect exposure (from soiled-bedding transfer) at the same or greater frequency than mice first exposed at 8 to 12 wk of age. These findings indicate that, at least for MNV, sentinel residence time can be extended from 3 to 12 mo without compromising the reliability of seroconversion, thus ultimately reducing sentinel animal numbers. This practice, combined with nonanimal testing modalities (for example, exhaust duct sampling), can increase the sensitivity and specificity of rodent surveillance programs and minimize the use of live animals.

Bluetongue in Europe – the risk of animal import from restricted zones

Bluetongue (BT) is a vector-borne viral disease effecting ruminants caused by bluetongue virus (BTV), transmitted mainly by bites from midges of the genus Culicoides. Since the end of 20th century, BTV is endemic in several European countries and the disease is caused mainly by BTV-8 and BTV-4 infections. Bluetongue virus is characterized by high genetic diversity. To date, over 29 BTV serotypes have been documented, including recently discovered atypical serotypes BTV (25–27). The disease has a high economic impact as it causes economic losses due to animal mortality, reduced productivity and restrictions on the movement of animals. Several reports and numerous observations indicate the contribution of animal movements to the spread of BTV infections. Thus, bluetongue surveillance that includes testing of sentinel animals as well as virological testing of animals susceptible to BTV infection imported from restricted zones due to the presence of BTV is a key factor in maintaining a BT-free status

Seroprevalence of Trichinella infections in domestic dogs from Slovakia

Trichinellosis is constantly present in the sylvatic cycle in Slovakia, with several sporadic human outbreaks registered since the 1960s. The largest outbreak of trichinellosis occurred in 1998 and was related to the consumption of dog meat that had been added to smoked pork sausages. The aim of this study was to estimate the seroprevalence of Trichinella infection in domestic dogs in various regions of Slovakia. Out of 439 dogs tested, 56 (12.8%) were classified as a seropositive based on the enzyme-linked immunosorbent assay (ELISA), with confirmation by Western blotting. The highest seropositivity was recorded among dogs from the eastern part of Slovakia, in the Prešov (22.9%) and Košice (17.1%) regions, long considered to be highly endemic for Trichinella occurrence and where the prevalence of infection in the vulpine population is also the highest in Slovakia. Trichinella-seropositive animals were detected significantly more often in dogs kept in rural areas (21.1%) when compared with animals living in towns or suburban localities (7.7%). On the other hand, neither age, nor gender and size of the dogs were shown to be a significant factor for Trichinella infection (P > 0.05). The present results indicate that the dog population in Slovakia is at high risk of exposure to Trichinella parasites and could potentially represent a suitable host group for serological monitoring of Trichinella infection as convenient sentinel animals.