The occurrence of elephant endotheliotropic herpesvirus infection in wild and captive Asian elephants in Thailand: Investigation based on viral DNA and host antibody

Background and Aim: Elephant endotheliotropic herpesvirus (EEHV) is a serious disease, threatening the life of young elephants. Many elephants have been infected with no clinical signs and may serve as carriers spreading this disease. It is important to monitor the disease through clinical signs and molecular diagnosis. In this study we investigated the occurrence of EEHV and the efficiency of different techniques used to monitor EEHV infection in various samples and populations of Asian elephants. Materials and Methods: Blood and trunk swabs were collected from live elephants, while visceral organs (lung, digestive tract, spleen, lymph nodes, and kidney) were collected from dead elephants. EEHV was detected by polymerase chain reaction (PCR) in whole blood, trunk swabs, and visceral organs as samples, while elephant anti-EEHV immunoglobulin G (IgG) in serum was detected by enzyme-linked immunosorbent assay (ELISA). A total of 162 samples were analyzed in this study: 129 from healthy, 26 from dead, and 7 from sick elephants. Results: The present study showed that the overall incidence of EEHV was 40.1% (n=65/162). Approximately 46.2% (n=12/26) and 85.7% (n=6/7) of dead and sick elephants were positive for EEHV by PCR, respectively. All sick elephants that were young and affected by EEHV clinical disease tested negative for the IgG antibody ELISA, suggesting primary EEHV infection in this group. In addition, 2.3% (n=3/129) of subclinical infections were detected using PCR, and trunk swab samples showed slightly higher sensitivity (5.3%, n=2/38) to detect EEHV than whole blood (1.2%, n=1/84). As many as, 48.4% (n=44/91) of healthy elephants were EEHV seropositive (ELISA-positive), suggesting that many elephants in Thailand had previously been infected. Overall, 30% of dead wild elephants had been infected with EEHV (n=3/10). Moreover, statistical analysis revealed no significant differences in the EEHV detection rate between different age groups or sexes (p>0.05). Conclusion: PCR is better than ELISA to detect EEHV active infection in dead/sick elephants and to monitor EEHV in young elephants. ELISA is suitable for detecting previous EEHV infection and carriers, particularly adults. Theoretically, we could use both PCR and ELISA to increase the sensitivity of testing, along with observing abnormal behavior to efficiently monitor this disease. Identification of EEHV carriers within elephant populations is important to prevent transmission to healthy individuals, especially young elephants with high mortality from EEHV. This is the first report from Thailand regarding EEHV infection in wild elephants, showing the importance of preventing disease transmission between captive and wild elephants

First detection and genetic characterization of canine bufavirus in domestic dogs, Thailand

Abstract Canine bufavirus (CBuV) was reported in domestic dogs worldwide. We conducted a survey of canine bufavirus in domestic dogs in Thailand from September 2016 to October 2022. Rectal swab samples (n = 531) were collected from asymptomatic dogs and dogs with gastroenteritis signs. The samples were tested for CBuV using PCR with specific primers to the VP1/VP2 gene, and 9.42% (50/531) was CBuV positive. Our findings showed that CBuVs could be detected in both symptomatic and healthy dogs. The Thai CBuVs were found in dogs from different age groups, with a significant presence in those under 1 year (12.60%) and dogs aged 1–5 years (7.34%) (p < 0.05), suggesting a high prevalence of Thai CBuVs in dogs under 5 years of age. We performed complete genome sequencing (n = 15) and partial VP1/VP2 sequencing (n = 5) of Thai CBuVs. Genetic and phylogenetic analyses showed that whole genomes of Thai CBuVs were closely related to Chinese and Italian CBuVs, suggesting the possible origin of Thai CBuVs. The analysis of VP1 and VP2 genes in Thai CBuVs showed that 18 of them were placed in subgroup A, while only 2 belonged to subgroup B. This study is the first to report the detection and genetic characterization of CBuVs in domestic dogs in Thailand. Additionally, surveillance and genetic characterization of CBuVs in domestic animals should be further investigated on a larger scale to elucidate the dynamic, evolution, and distribution of CBuVs

Cerebral cysticercosis in a wild Bengal tiger (Panthera tigris tigris) in Bhutan: a first report in non-domestic felids

The endangered Bengal tiger (Panthera tigris tigris) is a keystone species playing an essential role in ecology as well as in the social and spiritual lives of the Himalayan people. The latest estimate of the Bengal tiger population in Bhutan accounts for 103 individuals. Infectious organisms, including zoonotic parasites causing high burden in human health, have received little attention as a cause of mortality in tigers. Taeniosis/cysticercosis, caused by the cestode Taenia solium, is considered one of the major neglected tropical diseases in Southeast Asia. We present here a case of neurocysticercosis in a Bengal tiger showing advanced neurological disease outside Thimphu, the capital city of Bhutan. After palliative care, the animal died, and necropsy revealed multiple small cysts in the brain. Here we show the presence of two genetic variants of T. solium in the parasite material collected based on PCR and sequencing of the complete cox1 and cytB genes. The sequences form a discrete branch within the Asia plus Madagascar cluster of the parasite. On other hand, tests for feline morbillivirus, feline calicivirus, canine distemper virus, Nipah, rabies, Japanese encephalitis, feline leukaemia and feline immunodeficiency virus were negative. In contrast, PCR for feline herpesvirus was positive and a latex agglutination test revealed an elevated antibody titer against Toxoplasma gondii (titer 1:256). The molecular examination of taeniid eggs isolated from the tiger faeces produced sequences for which the highest homology in GenBank is between 92% and 94% with T. regis and T. hydatigena. This fatal case of T. solium neurocysticercosis, a disease previously unrecorded in tigers or other non-domestic felids, demonstrates an anthropogenically driven transmission of a deadly pathogen which could become a serious threat to the tiger population

Home range and habitat utilization of gaur (Bos gaurus) in transition zone between protected forest and human-dominated landscape, Eastern Thailand

Understanding the spatial ecology of an animal is crucial for its conservation and management, particularly for threatened species. The gaur (Bos gaurus), globally classified as vulnerable, is distributed across mainland South and Southeast Asia. In Thailand, the overall gaur population is decreasing, and suitable habitats are declining. Conversely, the gaur is well recovered in the Khao Phaeng Ma Non-hunting Area (KPM-NHA), a part of the Dong Phayayen-Khao Yai Forest Complex, recognized as a UNESCO Natural World Heritage site. Due to its abundance, this area faces the challenge of crop-raiding by gaurs. Thus, this research focuses on investigating the home range, movement, and habitat selection of gaurs in KPM-NHA and its surrounding areas. From October 2020 to July 2022, we obtained location data for 11 adult gaurs (eight males and three females) using a GPS-collar. We utilized the autocorrelated kernel density estimation (AKDE) method and the step-selection function (SSFs) to estimate the gaurs' home range, movement, and habitat selection. The results show that the gaur dwelled in KPM-NHA and moved around the protected areas and surrounding agricultural areas. The average home range size of males and females were 9.33 km2 (range 2.92–18.20 km2) and 4.09 km2 (range 1.44–6.11 km2), respectively. Regarding their movement, the average traveled distance was 6.38 km/day for males and 6.19 km/day for females. Gaurs preferred a lower canopy near the dry evergreen forest, grassland, field crop, rangeland, urban, and water body. The findings offer essential data for crafting an effective conservation approach. This information holds significance for public awareness and contributes to an improved strategy for mitigating human-gaur conflicts. Furthermore, the management of gaur habitats can utilize this data to establish guidelines, particularly for maintaining grasslands within protected areas

Mismatch distributions analysis.

The x-axis represents the number of pairwise differences (mismatches), while the y-axis represents the frequency of these differences. The observed mismatch distribution (red line) is compared to the expected distribution (blue line) for a stable population. (TIFF)</p

Haplotype network derived from nucleotide data for mitochondrial D-loop sequencing of wild bull (<i>Bos gaurus</i>, Smith, 1827) for 13 individuals.

Different colors distinguish the samples. Each circle represents a unique DNA sequence (haplotype), with the circle diameter reflecting the total number of individuals possessing the haplotype.</p

Global positioning system (GPS) tracks.

Thirteen wild gaurs in Khao Phaeng Ma (KPM) Non-Hunting Area, Thailand, 2021. (a) The gaur population group in KPM is divided into six subpopulations (Groups 1–6): a blue circle represents the groups dwelling in KPM, and a yellow circle represents the groups living outside the protected area; “xxxG” indicates the number of gaurs in each herd, (b) The overall home range area of male gaurs (Group 1 and Group 2), and their area of overlap in protected areas and agricultural areas.</p

Simulation results showing the relationship between generations and genetic diversity.

Simulation results showing the relationship between generations and genetic diversity.</p