Nine-year seroepidemiological study of severe fever with thrombocytopenia syndrome virus infection in feral horses in Cape Toi, Japan.

Severe fever with thrombocytopenia syndrome (SFTS) is a fatal zoonosis caused by ticks in East Asia. As SFTS virus (SFTSV) is maintained between wildlife and ticks, seroepidemiological studies in wildlife are important to understand the behavior of SFTSV in the environment. Miyazaki Prefecture, Japan, is an SFTS-endemic area, and approximately 100 feral horses, called Misaki horses (Equus caballus), inhabit Cape Toi in Miyazaki Prefecture. While these animals are managed in a wild-like manner, their ages are ascertainable due to individual identification. In the present study, we conducted a seroepidemiological survey of SFTSV in Misaki horses between 2015 and 2023. This study aimed to understand SFTSV infection in horses and its transmission to wildlife. A total of 707 samples from 180 feral horses were used to determine the seroprevalence of SFTSV using enzyme-linked immunosorbent assay (ELISA). Neutralization testing was performed on 118 samples. In addition, SFTS viral RNA was detected in ticks from Cape Toi and feral horses. The overall seroprevalence between 2015 and 2023 was 78.5% (555/707). The lowest seroprevalence was 55% (44/80) in 2016 and the highest was 92% (76/83) in 2018. Seroprevalence was significantly affected by age, with 11% (8/71) in those less than one year of age and 96.7% (435/450) in those four years of age and older (p < 0.0001). The concordance between ELISA and neutralization test results was 88.9% (105/118). SFTS viral RNA was not detected in ticks (n = 516) or feral horses. This study demonstrated that horses can be infected with SFTSV and that age is a significant factor in seroprevalence in wildlife. This study provides insights into SFTSV infection not only in horses but also in wildlife in SFTS-endemic areas.

Conserved Functions of Orthohepadnavirus X Proteins to Inhibit Type-I Interferon Signaling.

Orthohepadnavirus causes chronic hepatitis in a broad range of mammals, including primates, cats, woodchucks, and bats. Hepatitis B virus (HBV) X protein inhibits type-I interferon (IFN) signaling, thereby promoting HBV escape from the human innate immune system and establishing persistent infection. However, whether X proteins of Orthohepadnavirus viruses in other species display a similar inhibitory activity remains unknown. Here, we investigated the anti-IFN activity of 17 Orthohepadnavirus X proteins derived from various hosts. We observed conserved activity of Orthohepadnavirus X proteins in inhibiting TIR-domain-containing adaptor protein inducing IFN-ß (TRIF)-mediated IFN-ß signaling pathway through TRIF degradation. X proteins from domestic cat hepadnavirus (DCH), a novel member of Orthohepadnavirus, inhibited mitochondrial antiviral signaling protein (MAVS)-mediated IFNß signaling pathway comparable with HBV X. These results indicate that inhibition of IFN signaling is conserved in Orthohepadnavirus X proteins.

Detection and phylogenetic analysis of Dabieshan tick virus and Okutama tick virus in ticks collected from Cape Toi, Japan.

New technologies have led to the discovery of novel tick-borne and tick-associated viruses. Dabieshan tick virus (DaTV) and Okutama tick virus (OkTV), which belong to the family Phenuiviridae, were discovered in ticks in China and Japan, respectively, in the 2010s. Although it is unknown whether these viruses cause disease in animals or humans, all tick-associated viruses have the potential to become etiological agents of infectious diseases through gene reassortment. Therefore, it is important to elucidate the ecology of these viruses, regardless of their pathogenicity. In this study, ticks were collected year-round in Cape Toi, Miyazaki Prefecture, Japan, and an epidemiological survey of tick-associated phenuiviruses was performed. A total of 516 ticks collected from the vegetation by dragging flannel sheets were used for analysis. Pan-phenuivirus reverse transcription PCR was performed on the tick samples, and DaTV and OkTV were detected. We found that 37.0% (85/230) and 23% (16/71) of nymphal and adult Haemaphysalis longicornis were infected with DaTV, respectively, and 10% (6/62) and 13% (1/8) of nymphal and adult Haemaphysalis flava were infected with OkTV, respectively. Phylogenetic analysis indicated that the DaTV identified in this study formed a unique clade that was distinct from the strains identified in China. The survey revealed that DaTV is distributed not only in China, but also in Japan. We believe that this study contributes to our understanding of the prevalence of tick-associated viruses.

Serological survey on bovine viral diarrhea virus in man and evaluation of relation with Zika virus-associated microcephaly.

Background: In 2015, an unprecedented epidemic of microcephaly occurred in Brazil. Preliminary observations suggested the involvement of cofactors in the etiopathology of Zika virus-associated microcephaly. Bovine viral diarrhea virus (BVDV) was identified in fetal samples with microcephaly, originating in the state of Paraíba, and two virus sequences, obtained from the amniotic fluid collected from mothers with babies affected by Zika and microcephaly, have been characterized as two different species of BVDV, types 1 and 2. Aim: The involvement of BVDV as a co-factor in the etiopathogenesis of Zika virus-associated microcephaly was explored. Methods: A serological screening using an ELISA test was undertaken to detect antibodies against BVDV among patients referred to the Central Laboratory of Natal, Rio Grande do Norte, encompassing microcephalic babies and their mothers, mothers and pregnants not associated with microcephaly and general patients as a control group. Results: Two samples were positive out of 382 tested (0.52%). No specific relation with birth defects could be established. Conclusions: The study might suggest serological evidence of BVDV in humans. Further studies and the application of improved diagnostic tests adapted to humans are necessary to clarify the epidemiological extent and impact of BVDV.

Heavy metals content in fresh tuna and swordfish caught from Hindian and Pacific Oceans: Health risk assessment of dietary exposure.

Background and Aim: Yellowfin tuna and swordfish are seafood commodities commonly caught from deep oceans worldwide. Therefore, this study aimed to assess the levels of three heavy metals, namely, cadmium (Cd), lead (Pb), and mercury (Hg) in yellowfin tuna and swordfish. The results are expected to provide consumers with information on the safety of consuming or exporting these fishes caught in the Hindian and Pacific Oceans. Materials and Methods: Fresh yellowfin and swordfish were obtained from fishermen's catches in FAO Fishing Zone 57 (Indian Ocean) and 71 (Pacific Ocean) and then collected at Benoa Harbor, Bali Province. The comparative method was to evaluate the levels of heavy metals in each fish. Furthermore, heavy metal concentrations, including Pb, Cd, and Hg, were determined using atomic absorption spectroscopy analysis. These results were then used to assess the safety of these fishes by calculating the estimated daily intake (EDI) and target hazard quotients-total target hazard quotients (THQs-TTHQs). Results: The analysis showed that none of the samples exceeded the threshold levels for the three heavy metals, which was specified by the Indonesian National Standard (SNI) and European Commission Regulation (CR) No. 1881/2006. The EDI and provisional tolerable weekly index (PTWI) obtained in this study were still in the safe range. However, the PTWI values for Pb in yellowfin tuna product from the Indian Ocean were higher (0.0038 mg/kg) compared to the recommended standard for the adult population. The THQ-TTHQ values of fish caught from these oceans were also within the acceptable range specified by the two agencies, indicating that they are safe for consumption by people with various age groups and for export purposes. Conclusion: The average levels of three heavy metals (Cd, Pb, and Hg) in muscle samples of yellowfin tuna and swordfish caught from the Pacific and Hindian Oceans were within the acceptable range as specified by the SNI and CR No. 1881/2006. Furthermore, the EDI and THQs values indicated that fishes caught from the Pacific and Hindian Oceans were safe for consumption. This research is still limited to assessing two capture fisheries commodities. Further research is needed on the assessment of heavy metal levels in other capture fisheries commodities in this capture zone.

The Immunoprotection of OmpH Gene Deletion Mutation of Pasteurella multocida on Hemorrhagic Sepsis in Qinghai Yak.

OmpH is among the most important virulence factors of Pasteurella multocida, which mediates septicemia in yaks (Bos grunniens I) after infection with the bacteria. In the present study, yaks were infected with wild-type (WT) (P0910) and OmpH-deficient (ΔOmpH) P. multocida strains. The mutant strain was generated through the reverse genetic operation system of pathogens and proteomics technology. The live-cell bacterial count and clinical manifestations of P. multocida infection in Qinghai yak tissues (thymus, lung, spleen, lymph node, liver, kidney, and heart) were analyzed. The expression of differential proteins in the yak spleen under different treatments was analyzed using the marker-free method. We found that compared with the mutant strain, the titer of wild-type strains was significantly higher in tissues. Additionally, compared with other organs, the bacteria titer was significantly higher in the spleen. Compared with the WT p0910 strain, the mutant strain generated milder pathological changes in the tissues of yak. Proteomics analysis revealed that 57 of the 773 proteins expressed in P. multocida were significantly differentially expressed between the ΔOmpH and P0910 groups. Of the 57, 14 were over-expressed, whereas 43 were under-expressed. The differentially expressed proteins in the ΔompH group regulated the ABC transporter (ATP-powered translocation of many substrates across membranes) system, the two-component system, RNA degradation, RNA transcription, glycolysis/gluconeogenesis, biosynthesis of ubiquinone and other terpenoid-quinones, oxidative phosphorylation (citrate cycle) as well as fructose and mannose metabolism. The relationship among 54 significantly regulated proteins was analyzed using STRING. We found that WT P0910 and ΔOmpH of P. multocida infection activated the expression of ropE, HSPBP1, FERH, ATP10A, ABCA13, RRP7A, IL-10, IFN-γ, IL-17A, EGFR, and dnaJ. Overall, deletion of the OmpH gene weakened the virulence but maintained the immunogenicity of P. multocida in yak. The findings of this study provide a strong foundation for the pathogenesis of P. multocida and the management of related septicemia in yaks.

Possible Transmission of Severe Fever with the Thrombocytopenia Syndrome Virus to an Individual Who Buried an Infected Cat.

Severe fever with thrombocytopenia syndrome (SFTS) is caused by the severe fever with thrombocytopenia syndrome virus (SFTSV). Although SFTS is a fatal tick-borne zoonosis, it can infect humans without tick bite exposure. Recently, direct transmission of SFTSV from companion pets to humans has become a major problem. We present a case of SFTSV transmission from a dead community cat to a woman who buried the cat in Miyazaki Prefecture, Japan. The community cat died without a diagnosis of SFTS, and the woman buried it without taking any precautions. She developed symptoms of SFTS 9 days later. The woman tested positive for SFTS viral RNA and anti-SFTSV antibodies. The cat's carcass was exhumed, and tissue samples were collected to confirm the viral infection. Numerous copies of viral RNA were detected. The SFTSV M segment sequences in the cat and the woman were 100% homologous. The woman claimed that she had touched blood that had leaked from the cat's body while burying it. However, she could have been infected while transporting the cat to the animal hospital. This study highlights the risk of SFTSV infection from contact with sick or dead community cats.

Development of a direct duplex real-time PCR assay for rapid detection of domestic cat hepadnavirus.

Domestic cat hepadnavirus (DCH) is a novel hepadnavirus, first identified in 2018. DCH is generally detected using conventional PCR assays, which include time-consuming agarose gel electrophoresis. We developed a rapid, sensitive, and specific real-time PCR (rtPCR) assay for the detection of the DCH genome. To streamline the procedure, our rtPCR assay was carried out using blood samples, without DNA extraction. A consensus primers/probe set was designed based on the nucleotide sequences of the surface/polymerase gene of all DCH strains available in GenBank. To exclude the possibility that the PCR reaction was blocked by anticoagulants, we also used a primers/probe set for amplifying the cat beta-actin gene as a reference gene. Our direct duplex rtPCR assay had high sensitivity, with a limit of detection of 10 copies/µL of blood for DCH. Our direct duplex rtPCR assay should be a useful tool for DCH detection and surveillance.

Nosocomial Severe Fever with Thrombocytopenia Syndrome in Companion Animals, Japan, 2022.

In Japan, 2 cats that underwent surgery in a room where a sick dog had been euthanized became ill within 9 days of surgery. Severe fever with thrombocytopenia syndrome virus was detected in all 3 animals; nucleotide sequence identity was 100%. Suspected cause was an uncleaned pulse oximeter probe used for all patients.

Seroprevalence of severe fever with thrombocytopenia syndrome virus in medium-sized wild mammals in Miyazaki, Japan.

Severe fever with thrombocytopenia syndrome (SFTS) is a fatal emerging tick-borne zoonotic disease caused by the SFTS virus (SFTSV). SFTSV infection in humans and companion animals is a matter of concern in endemic areas. Various wild animals are involved in the transmission cycle of SFTSV with vector ticks. Because the home range of medium-sized wild mammals commonly overlaps with humans' living spheres, this study aimed to reveal the endemicity of SFTSV in such mammals. This study investigated the prevalence of antibodies against SFTSV and viral RNA in medium-sized wild mammals in Miyazaki Prefecture, Japan where human cases have been most frequently reported in Japan and performed a phylogenetic analysis to compare the detected SFTSV with those previously reported. Forty-three of 63 (68%) Japanese badgers (Meles anakuma) and 12 of 53 (23%) Japanese raccoon dogs (Nyctereutes procyonoides viverrinus) had antibodies against SFTSV. Japanese marten (n = 1), weasels (n = 4), and Japanese red fox (n = 1) were negative. Two of 63 (3%) badgers tested positive for SFTSV RNA, whereas the other species were negative. Phylogenetic analysis of the partial nucleotide sequence of SFTSV revealed that viral RNA detected from badgers exhibited 99.8% to 100% similarity to SFTSV, as previously reported in humans, cat, and ticks in the study area. This study demonstrated high seropositivity of antibodies in medium-sized wild mammals and suggested that SFTSV could be shared among these mammals, humans, and companion animals in endemic areas.

Usefulness of a new DUV-LED device for the control of infection by Escherichia coli, Staphylococcus aureus, mycobacteria and spore-forming bacteria.

Reliable disinfection and sterilization technologies are needed to deal with the various infectious diseases spreading around the world. Furthermore, bacteria that are difficult to eliminate by ordinary disinfection are also a problem in the medical environment. We examined the germicidal effect of a newly developed deep-ultraviolet light-emitting diode (DUV-LED) prototype device (wavelength of 280 ± 5 nm; power of 0.9 to 1.4 mW/cm2) for floor sterilization against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Mycobacterium gordonae (M. gordonae), and Bacillus subtilis (B. subtilis). This prototype device is equipped with highly practical DUV-LEDs with a high output efficiency and a long life, and was designed with consideration of the irradiation distance and the angle of the DUV-LEDs to provide a uniform irradiation rate. We found a statistically significant reduction of ≥90% in the infectious titers of both E. coli and S. aureus after irradiation for 2 s. Although acid-fast bacilli and spore-type bacilli are generally thought to be resistant to UV light irradiation compared to general bacteria, the acid-fast bacillus M. gordonae was inactivated after irradiation for 10 s, and spore-type cells of the bacillus B. subtilis were inactivated by ≥90% after irradiation for 30 s. We also found that the effects were cumulative when irradiation was performed at intervals. In the future, the usefulness of this device as an infection control measure will be evaluated in daily medical practice.

Generation of a bovine cell line for gene engineering using an HIV-1-based lentiviral vector.

Human immunodeficiency virus type 1 (HIV-1)-based lentiviral vectors are indispensable tools for gene engineering in mammalian cells. Conversely, lentiviral vector transduction is severely inhibited in bovine cells. Previous studies demonstrated that this inhibition is caused by the anti-lentiviral host factor tripartite motif containing 5 (TRIM5), which targets incoming HIV-1 virions by interacting with the viral capsid. In this study, we investigated several methods for overcoming the limited applicability of lentiviral vectors in bovine cells. First, we demonstrated that the SPRY domain of bovine TRIM5 is the major determinant of anti-viral activity. Second, we found that mutations that allow the capsid to evade rhesus macaque TRIM5α minimally rescued HIV-1 infectivity in bovine-derived MDBK cells. Third, we found that cyclosporine A, which relieves the inhibition of HIV-1 infection in monkey cells, significantly rescued the impaired HIV-1 infectivity in MDBK cells. Lastly, we successfully generated a bovine cell line lacking intact TRIM5 using the CRISPR/Cas9 technique. This TRIM5 knockout cell line displayed significantly higher susceptibility to an HIV-1-based lentiviral vector. In conclusion, our findings provide a promising gene engineering strategy for bovine cells, thereby contributing to innovations in agriculture and improvements in animal health.

Global Prevalence of Domestic Cat Hepadnavirus: An Emerging Threat to Cats' Health?

Hepatitis B is an infectious hepatocellular disease of global concern caused by hepatitis B virus (HBV), which belongs to Hepadnaviridae. Recently, a novel HBV-like virus, domestic cat hepadnavirus (DCH), was detected from an immunocompromised cat with a hepatic disease in Australia. Subsequent molecular investigation by independent research groups revealed that its prevalence rates were 6.5% in Australia, 10.8% in Italy, 12.4% in Thailand, 12.3% in Malaysia, 3.08% in the United Kingdom, and 0.78% in Japan. Although the correlation between DCH infection and hepatic diseases remains to be elucidated, understanding the diversity of circulating DCH will contribute to its prevention and control in domestic cats. Herein, we summarize the current epidemiological data of DCH in these countries.

Highly polymerized proanthocyanidins (PAC) components from blueberry leaf and stem significantly inhibit SARS-CoV-2 infection via inhibition of ACE2 and viral 3CLpro enzymes.

With the current worldwide pandemic of COVID-19, there is an urgent need to develop effective treatment and prevention methods against SARS-CoV-2 infection. We have previously reported that the proanthocyanidin (PAC) fraction in blueberry (BB) leaves has strong antiviral activity against hepatitis C virus (HCV) and human T-lymphocytic leukemia virus type 1 (HTLV-1). In this study, we used Kunisato 35 Gou (K35) derived from the rabbit eye blueberry (Vaccinium virgatum Aiton), which has a high PAC content in the leaves and stems. The mean of polymerization (mDP) of PAC in K35 was the highest of 7.88 in Fraction 8 (Fr8) from the stems and 12.28 of Fraction 7 (Fr7) in the leaves. The composition of BB-PAC in K35 is that most are B-type bonds with a small number of A-type bonds and cinchonain I as extension units. A strong antiviral effect was observed in Fr7, with a high polymerized PAC content in both the leaves and stems. Furthermore, when we examined the difference in the action of BB-PAC before and after SARS-CoV-2 infection, we found a stronger inhibitory effect in the pre-infection period. Moreover, BB-PAC Fr7 inhibited the activity of angiotensin II converting enzyme (ACE2), although no effect was observed in a neutralization test of pseudotyped SARS-CoV-2. The viral chymotrypsin-like cysteine protease (3CLpro) of SARS-CoV-2 was also inhibited by BB-PAC Fr7 in leaves and stems. These results indicate that BB-PAC has at least two different inhibitory effects, and that it is effective in suppressing SARS-CoV-2 infection regardless of the time of infection.

Survey of hepatitis E virus in pork products and pig stools in Nakhon Pathom Province, Thailand.

BACKGROUND: Hepatitis E virus (HEV) is an important public health threat resulting in more than 3 million symptomatic cases and 70,000 deaths annually. HEV is classified into at least eight genotypes, and five are associated with human infection. Genotypes 1 and 2 primarily affect humans, whereas genotypes 3 and 4 circulate in both humans and swine and are considered zoonotic viruses. Previous studies in Central Thailand have reported human HEV isolates with high similarity to swine strains and high seroprevalence in pigs, suggesting the potential for pig-to-human transmission. OBJECTIVES: This study aimed to detect and analyse HEV in pork products and pig stools collected from local markets and pig farms in Nakhon Pathom Province in Central Thailand. METHODS: A total of 177 pig stool and 214 pork product samples were detected for HEV by using RT-PCR amplification. Next, nucleotide sequencing and phylogenetic analysis were performed. RESULTS: We found one sample of pork products (1/214, 0.5%), which was a pig liver sample (1/51, 2.0%), and 49 HEV-positive samples in pig stools (49/177, 27.7%). Phylogenetic analysis showed that all these HEV sequences belonged to genotype 3, with a high correlation between our samples and HEV from humans and swine was previously reported in Thailand. CONCLUSIONS: This study suggested that the consumption of poorly sanitized or uncooked animal meat or food and frequent exposure to pig stools may be risk factors for HEV infections in humans.

Virucidal activity and mechanism of action of cetylpyridinium chloride against SARS-CoV-2.

Objective: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen causing the coronavirus disease 2019 (COVID-19) global pandemic. Recent studies have shown the importance of the throat and salivary glands as sites of virus replication and transmission. The viral host receptor, angiotensin-converting enzyme 2 (ACE2), is broadly enriched in epithelial cells of the salivary glands and oral mucosae. Oral care products containing cetylpyridinium chloride (CPC) as a bactericidal ingredient are known to exhibit antiviral activity against SARS-CoV-2 in vitro. However, the exact mechanism of action remains unknown. Methods: This study examined the antiviral activity of CPC against SARS-CoV-2 and its inhibitory effect on the interaction between the viral spike (S) protein and ACE2 using an enzyme-linked immunosorbent assay. Results: CPC (0.05%, 0.1% and 0.3%) effectively inactivated SARS-CoV-2 within the contact times (20 and 60 s) in directions for use of oral care products in vitro. The binding ability of both the S protein and ACE2 were reduced by CPC. Conclusions: Our results suggest that CPC inhibits the interaction between S protein and ACE2, and thus, reduces infectivity of SARS-CoV-2 and suppresses viral adsorption.

Whole-Genome Sequencing of Pasteurella multocida Strain Pm1, Isolated from a Calf.

Bovine pneumonia is a disease that causes significant economic losses in livestock industries and is vital for animal welfare. The whole-genome sequence of Pasteurella multocida strain Pm1, isolated from a calf suffering from pneumonia in Japan, is reported here.

Identification of domestic cat hepadnavirus from a cat blood sample in Japan.

The hepatitis B virus (Hepadnaviridae) induces chronic hepatitis and hepatic cancer in humans. A novel domestic cat hepadnavirus (DCH) was recently identified in several countries, however, the DCH infection status of cats in Japan is unknown. Therefore, we investigated the DCH infection rate of 139 cat samples collected in Japan. We identified one positive blood sample (0.78%) from a 17-year-old female cat with chronically elevated alanine aminotransferase. Phylogenetic analysis demonstrated that the DCH strain identified in this study is genetically different from strains in other countries. Further investigations are required to elucidate the evolution of DCH and the impact of DCH infection on hepatic diseases in domestic cats.

Rapid inactivation of Dabie bandavirus (SFTSV) by irradiation with deep-ultraviolet light-emitting diode.

Severe fever with thrombocytopenia syndrome (SFTS) caused by Dabie bandavirus (SFTSV) is a serious public health concern in endemic areas, particularly in Asian and Southeast Asian countries. SFTSV is transmitted by direct contact with body fluids from infected humans and animals. Therefore, environmental hygiene in hospitals and veterinary clinics in SFTSV-endemic areas is highly important. This study assessed the effects of continuous and intermittent irradiation with deep-ultraviolet light-emitting diode (DUV-LED) on SFTSV. Evaluation was performed by conducting plaque assay in which SFTSV irradiated with deep-ultraviolet (DUV; 280 ± 5 nm) was inoculated onto Vero cells. The results showed that continuous and intermittent irradiation for 5 s, resulting in 18.75 mJ/cm2 of cumulative UV exposure, led to a >2.7 and >2.9 log reduction, respectively, corresponding to a >99.8% reduction in infectivity. These results demonstrate that DUV can be utilized for inactivation of SFTSV to maintain environmental hygiene in hospitals and veterinary clinics in endemic countries.

Retrospective study on the possibility of an SFTS outbreak associated with undiagnosed febrile illness in veterinary professionals and a family with sick dogs in 2003.

INTRODUCTION: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-born disease and its animal-to-human transmission has come to attention recently. During our sero-survey of SFTS virus (SFTSV) among veterinary professionals in 2018, a veterinarian and his assistant working in an animal hospital were tested positive by enzyme-linked immunosorbent assay (ELISA). An additional survey implied a cluster of SFTS cases in which four more people, a family who brought two sick dogs to the animal hospital in 2003, were involved. This study aimed at assessing the possibility of animal-to-human transmission of SFTSV in this cluster. METHODS: Retrospective interviews were performed with the owner family of the dogs and their clinical records were obtained from each hospital. SFTSV-IgG were tested by ELISA and virus neutralization test using the sera collected from them in 2018. RESULTS: The interviews revealed that a total of six people, the two veterinary professionals and the owner family who took care of the sick dogs, suffered from SFTS-like symptoms in the same period of time in 2003. All patients did not have tick bite before the onset and all suspected causative agents were excluded by laboratory tests. The serological tests in this study revealed the four owner family members were all positive for SFTSV antibodies. CONCLUSIONS: Considering the extremely low seroprevalence of SFTSV antibodies among inhabitants of the region, the existence of SFTSV antibodies in all these six people presents a possibility that they were involved in an SFTS outbreak originated in the sick dogs in 2003.