Sero-epidemiological investigation and cross-neutralization activity against SARS-CoV-2 variants in cats and dogs, Thailand.

Epidemiological data on SARS-CoV-2 infection in companion animals have been thoroughly investigated in many countries. However, information on the neutralizing cross-reactivity against SARS-CoV-2 variants in companion animals is still limited. Here, we explored the neutralizing antibodies against SARS-CoV-2 in cats and dogs between May 2020 and December 2021 during the first wave (a Wuhan-Hu-1-dominant period) and the fourth wave (a Delta-dominant period) of the Thailand COVID-19 outbreak. Archival plasma samples of 1,304 cats and 1,795 dogs (total = 3,099) submitted for diagnosis and health checks were collected at the Prasu-Arthorn Veterinary Teaching Hospital, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom. A microneutralization test was used to detect neutralizing antibodies against the ancestral Wuhan-Hu-1 and the Delta variants. A plasma sample with neutralizing titers ≥10 was considered positive. Our results showed relatively low seroprevalence with seropositive samples detected in 8 out of 3,099 individuals (0.26, 95% CI 0.11-0.51%). Among these cases, SARS-CoV-2 neutralizing antibodies from both the ancestral Wuhan-Hu-1 and the Delta variants were found in three out of eight cases in two cats (n = 2) and one dog (n = 1). Furthermore, neutralizing antibodies specific to only the ancestral Wuhan-Hu-1 variant were exclusively found in one cat (n = 1), while antibodies against only the Delta variant were detected in four dogs (n = 4). Additionally, the neutralizing cross-activities against SARS-CoV-2 variants (Alpha, Beta, and Omicron BA.2) were observed in the seropositive cats with limited capacity to neutralize the Omicron BA.2 variant. In summary, the seropositivity among cats and dogs in households with an unknown COVID-19 status was relatively low in Thailand. Moreover, the neutralizing antibodies against SARS-CoV-2 found in the seropositive cats and dogs had limited or no ability to neutralize the Omicron BA.2 variant. Thus, monitoring SARS-CoV-2 infection and sero-surveillance, particularly in cats, is imperative for tracking virus susceptibility to the emergence of new SARS-CoV-2 variants.

Tick-borne pathogens Ehrlichia, Hepatozoon, and Babesia co-infection in owned dogs in Central Thailand.

Tick-borne pathogens are transmitted by a wide range of tick species and affect both human and animal health. Understanding the diversity of these pathogens and their co-infection rates in domesticated animals in urban areas is crucial for effective disease management and prevention. In this study, a total of 565 owned dogs in the central region of Thailand were investigated for the infection rate of three genera of Ehrlichia, Hepatozoon, and Babesia infection using multiplex PCR. The results revealed an overall infection rate of 19.1%, with Ehrlichia having the highest infection rate (12.2%), followed by Babesia (2.5%) and Hepatozoon (1.4%). The rate of co-infection was 3%, with mixed infections involving two or three genera. Male dogs exhibited a slightly higher infection rate compared to females, although not statistically significant. Young adult dogs (1-3 years) showed the highest infection rate of both single infections and co-infections. Monthly infection rate indicated variations throughout the year, with co-infection rate significantly associated with overall infection rate. Clinical manifestations in three genera of infected dogs included thrombocytopenia and eosinopenia. The results of this study are useful to design strategies for the management and prevention of tick-borne diseases in the study area.

Serological and Molecular Surveillance for SARS-CoV-2 Infection in Captive Tigers (Panthera tigris), Thailand.

Coronavirus disease (COVID-19) is an emerging infectious disease caused by SARS-CoV-2. Given the emergence of SARS-CoV-2 variants, continuous surveillance of SARS-CoV-2 in animals is important. To monitor SARS-CoV-2 infection in wildlife in Thailand, we collected 62 blood samples and nine nasal- and rectal-swab samples from captive tigers (Panthera tigris) in Ratchaburi province in Thailand during 2020-2021. A plaque reduction neutralization test (PRNT) was employed to detect SARS-CoV-2 neutralizing antibodies. A real-time RT-PCR assay was performed to detect SARS-CoV-2 RNA. Our findings demonstrated that four captive tigers (6.5%, 4/62) had SARS-CoV-2 neutralizing antibodies against Wuhan Hu-1 and the Delta variant, while no SARS-CoV-2 RNA genome could be detected in all swab samples. Moreover, a low-level titer of neutralizing antibodies against the Omicron BA.2 subvariant could be found in only one seropositive tiger. The source of SARS-CoV-2 infection in these tigers most likely came from close contact with the infected animals' caretakers who engaged in activities such as tiger petting and feeding. In summary, we described the first case of natural SARS-CoV-2 infection in captive tigers during the COVID-19 outbreak in Thailand and provided seroepidemiological-based evidence of human-to-animal transmission. Our findings highlight the need for continuous surveillance of COVID-19 among the captive tiger population and emphasize the need to adopt a One Health approach for preventing and controlling outbreaks of COVID-19 zoonotic disease.

Zoonotic pathogens survey in free-living long-tailed macaques in Thailand.

Long-tailed macaques (Macaca fascicularis) are known to harbour a variety of infectious pathogens, including zoonotic species. Long-tailed macaques and humans coexist in Thailand, which creates potential for interspecies pathogen transmission. This study was conducted to assess the presence of B virus, Mycobacterium spp., simian foamy virus (SFV), hepatitis B virus (HBV), and Plasmodium spp. in 649 free-living Thai long-tailed macaques through polymerase-chain reaction. DNA of SFV (56.5%), HBV (0.3%), and Plasmodium spp. (2.2%) was detected in these macaques, whereas DNA of B virus and Mycobacterium spp. was absent. SFV infection in long-tailed macaques is broadly distributed in Thailand and is correlated with age. The HBV sequences in this study were similar to HBV sequences from orangutans. Plasmodium spp. DNA was identified as P. inui. Collectively, our results indicate that macaques can carry zoonotic pathogens, which have a public health impact. Surveillance and awareness of pathogen transmission between monkeys and humans are important.

Molecular study of feline hemoplasmas in free- ranging fishing cats (Prionailurus viverrinus) in Thailand.

Feline hemoplasmas, consisting of Mycoplasma haemofelis (M. haemofelis), Candidatus Mycoplasma haemominutum (Ca. M. haemominutum), and Candidatus Mycoplasma turicensis (Ca. M. turicensis), cause feline infectious anemia and zoonoses. Using multiplex PCR and phylogenetic analysis based on 16S rRNA, 22 blood samples from fishing cats (Prionailurus viverrinus) living in Khao Sam Roi Yot National Park, Thailand were determined positive for M. haemofelis (13.6%)and Ca. M. haemominutum (22.7%). M. haemofelis and Ca. M. haemominutum infection can result severe anemia and asymptomatic, respectively. However, not all positive cases exhibit anemia symptoms. Future study of hemoplasma infection in wild felids is necessary for conservation and the preservation of public health in Thailand.

Detection and characterization of Chlamydophila psittaci in asymptomatic feral pigeons (Columba livia domestica) in central Thailand.

OBJECTIVE: To detect and characterize Chlamydophila psittaci (C. psittaci) in asymptomatic feral pigeons in central Thailand. METHODS: A total 814 swabs from the trachea and cloacae of 407 non-clinical feral pigeons in central Thailand were collected and tested for the presence of C. psittaci. RESULTS: A 10.8% of feral pigeons in the sample group were positive as determined by nested PCR primer specific to C. psittaci. The outer membrane protein A (ompA) gene of positive samples exhibited amino acid identity of C. psittaci ranging from 71 to 100% and were grouped in genotype B. Exceptionally, BF1676-56 isolate was closely related to Chlamydia avium with 99% identification of the 16S ribosomal (r) RNA gene. CONCLUSIONS: This is the first report on C. psittaci isolated from asymptomatic feral pigeons in Thailand, which provides knowledge for the disease status in pigeon populations in Thailand.

Development of a SYBR Green I-based real-time PCR for detection of elephant endotheliotropic herpesvirus 1 infection in Asian elephants (Elephas maximus).

Elephant endotheliotropic herpesvirus 1 (EEHV1) can cause fatal hemorrhagic disease in Asian elephants (Elephas maximus). Several studies have described this virus as a major threat to young Asian elephants. A SYBR Green I-based real-time polymerase chain reaction (PCR) was developed to identify EEHV1 on trunk swabs and necropsied tissues. Two of 29 (6.9%) trunk swab samples from healthy Asian elephants were positive for EEHV1. The viruses were analyzed and classified as EEHV1A based on 231 nucleotides of the terminase gene. Necropsied spleen and heart tissue showed the highest level and second highest levels of DNA virus copy accumulation, respectively. The detection limit of the test was 276 copies/µl of DNA. There was no cross-reaction with other mammalian herpesviruses, such as herpes simplex virus 1 and equine herpesvirus 2. Inter- and intra-assay showed low coefficients of variation values indicating the reproducibility of the test. The results indicated that the test can be practically used for epidemiological study, clinical diagnosis, and management and control of EEHV1.

First report of Ctenocephalides felis felis on the Asiatic Golden Cat, Catopuma temminckii in Thailand.

The cat flea, Ctenocephalidesfelisfelis (Siphonaptera: Pulicidae) has been reported to parasitize many species of wild and domestic animals and could serve as a vector of zoonotic pathogens. This is the first report of the presence of cat fleas on the Asiatic Golden Cat, Catopuma temminckii (Carnivora: Felidae), quarantined in Khao Pratabchang Wildlife and Breeding Center, Ratchaburi Province, Thailand. The findings of this report may be helpful in evaluating the potential risks associated with increased contact between wild and domestic animals and humans in this region.

Genetic analysis of beak and feather disease virus isolated from captive psittacine birds in Thailand.

Beak and feather disease virus (BFDV) is a causative agent of psittacine beak and feather disease. Genome sequences of BFDVs isolated from Thailand have not hitherto been reported. The whole genomes of 17 BFDV isolates, obtained from 12 psittacine genera, were amplified and subjected to direct sequencing revealing a length ranging from 1,990 to 2,015 nucleotides. The predicted open reading frames (ORFs) in the viral genome varied from four to six. Only ORF1, ORF2, and ORF5 were found in all isolates. Deduced amino acid sequences of BFDV ORF2 were used to construct a phylogenetic tree. The phylogram grouped BFDV into ten clusters, which showed either host species relationship or regional restriction. The Thai isolates, were grouped into three clusters, cluster I, II, and V. Cluster I and II showed restricted geographical region to Thailand, and cluster II also showed a close relationship with BFDV isolated from Australia. Cluster V demonstrated neither restricted region nor species specificity of birds. In this cluster, there was an insertion of 16 nucleotides at non coding region of all BFDV isolates. The genetic information obtained from this study can be used to help understand BFDV diversity and evolution in Thailand.