Seasonal Variation in Sexual Size Dimorphism in the Wrinkle-lipped Free-tailed Bat (Chaerephon plicatus Buchannan, 1800) Population in the Khao Chong Phran Non-hunting Area, Thailand

The Khao Chong Phran Non-hunting Area has the largest population of wrinkle-lipped free-tailed bats (Chaerephon plicatus) in Thailand. We examined monthly variations in sexual size dimorphism through measurements of forearm length and body mass during 2016. Bats were captured in each month at dawn and dusk. Individuals were sexed, aged, measured and marked before release. During the year, we caught 1,715 individuals. Of these, we used only adult, non-pregnant individuals (405 males and 538 females) for our analysis. Males had significantly larger forearm lengths and body masses than females. The body masses of both sexes peaked at the beginning and end of the rainy season, and bats captured at dawn were heavier than those netted at dusk. Seasonal fluctuations in body mass were correlated with monthly variation in rainfall; the positive correlation is likely explained by the greater insect abundance during wet months. The climate in western Thailand is expected to become warmer and drier, with likely negative effects on populations of this species due to reductions in insect food resources. Maintenance of this large population of C. plicatus in the study area will depend on concerted conservation efforts and further research focused on population dynamics, prey availability and foraging habitats

Autoimmune causes of encephalitis syndrome in Thailand: prospective study of 103 patients

Background: Data on encephalitis in Thailand have not been completely described. Etiologies remain largely unknown. We prospectively analyzed 103 Thai patients from 27 provinces for the causes of encephalitis using clinical, microbiological and neuroimaging indices; caseswithout a diagnosis were evaluated for autoimmune causes of encephalitis. Methods: Patients with encephalitis and/or myelitis were prospectively studied between October 2010 and August 2012. Cases associated with bacterial, rickettsial and mycobacterial diseases were excluded. Herpes viruses 1-6 and enteroviruses infection was diagnosed using PCR evaluation of CSF; dengue and JE viruses infection, by serology. The serum of test-negative patients was evaluated for the presence of autoantibodies. Results: 103 patients were recruited. Fifty-three patients (52%) had no etiologies identified. Twenty-five patients (24%) were associated with infections. Immune encephalitis was found in 25 (24%); neuropsychiatric lupus erythematosus (4), demyelinating diseases (3), Behcet’s disease (1) and the remaining had antibodies to NMDAR (5), ANNA-2 (6), Yo (2), AMPA (1), GABA (1), VGKC (1) and NMDA coexisting with ANNA-2 (1). Presenting symptoms in the autoimmune group included behavioral changes in 6/25 (versus 12/25 in infectious and 13/53 in unknown group) and as psychosis in 6/25 (versus 0/25 infectious and 2/53 unknown). Seizures were found in 6/25 autoimmune, 4/25 infectious and 19/53 unknown group. Two patients with anti-ANNA-2 and one anti-Yo had temporal lobe involvement by magnetic resonance imaging. Two immune encephalitis patients with antibodies to NMDAR and ANNA-2 had ovarian tumors. Conclusions: Autoantibody-associated encephalitis should be considered in the differential diagnosis and management algorithm regardless of clinical and neuroimaging features

Rabies virus strains circulating in Bhutan: implications for control.

We report a molecular epidemiological study of rabies virus strains circulating in animal populations in Bhutan, and investigate potential origins of these viruses. Twenty-three rabies virus isolates originating from dogs and other domestic animals were characterized by sequencing the partial nucleoprotein (N) gene (395 bp). Phylogenetic analysis was conducted and the Bhutanese isolates were compared with rabies viruses originating from other parts of the world. Phylogenetic analysis showed that Bhutanese isolates were highly similar and were closely related to Indian strains and South Asian Arctic–like–1 viruses. Our study suggests that the rabies viruses spreading in southern parts of Bhutan have originated from a common ancestor, perhaps from the Indian virus strain. Keywords: molecular epidemiology, rabies, Arctic–like virus, BhutanThailand Research Fund (grant No.DBG5180026

Rabies virus strains circulating in Bhutan: implications for control.

postprintWe report a molecular epidemiological study of rabies virus strains circulating in animal populations in Bhutan, and investigate potential origins of these viruses. Twenty-three rabies virus isolates originating from dogs and other domestic animals were characterized by sequencing the partial nucleoprotein (N) gene (395 bp). Phylogenetic analysis was conducted and the Bhutanese isolates were compared with rabies viruses originating from other parts of the world. Phylogenetic analysis showed that Bhutanese isolates were highly similar and were closely related to Indian strains and South Asian Arctic–like–1 viruses. Our study suggests that the rabies viruses spreading in southern parts of Bhutan have originated from a common ancestor, perhaps from the Indian virus strain. Keywords: molecular epidemiology, rabies, Arctic–like virus, BhutanThailand Research Fund (grant No.DBG5180026

Survey for Bat Lyssaviruses, Thailand

Surveillance for lyssaviruses was conducted among bat populations in 8 provinces in Thailand. In 2002 and 2003, a total of 932 bats of 11 species were captured and released after serum collection. Lyssavirus infection was determined by conducting virus neutralization assays on bat serum samples. Of collected samples, 538 were either hemolysed or insufficient in volume, which left 394 suitable for analysis. These samples included the following: Pteropus lylei (n = 335), Eonycteris spelaea (n = 45), Hipposideros armiger (n = 13), and Rousettus leschennaulti (n = 1). No serum samples had evidence of neutralizing antibodies when tested against rabies virus. However, 16 samples had detectable neutralizing antibodies against Aravan virus, Khujand virus, Irkut virus, or Australian bat lyssavirus; all were specifically associated with fruit bats P. lylei (n = 15) and E. spelaea (n = 1). These results are consistent with the presence of naturally occurring viruses related to new putative lyssavirus genotypes

Bat Nipah Virus, Thailand

Surveillance for Nipah virus (NV) was conducted in Thailand's bat population. Immunoglobulin G antibodies to NV were detected with enzyme immunoassay in 82 of 1,304 bats. NV RNA was found in bat saliva and urine. These data suggest the persistence of NV infection in Thai bats

More Accurate Insight into the Incidence of Human Rabies in Developing Countries through Validated Laboratory Techniques

International audienceNo abstract availabl

Transmission dynamics of rabies virus in Thailand: Implications for disease control

BACKGROUND: In Thailand, rabies remains a neglected disease with authorities continuing to rely on human death statistics while ignoring the financial burden resulting from an enormous increase in post-exposure prophylaxis. Past attempts to conduct a mass dog vaccination and sterilization program have been limited to Bangkok city and have not been successful. We have used molecular epidemiology to define geographic localization of rabies virus phylogroups and their pattern of spread in Thailand. METHODS: We analyzed 239 nucleoprotein gene sequences from animal and human brain samples collected from all over Thailand between 1998 and 2002. We then reconstructed a phylogenetic tree correlating these data with geographical information. RESULTS: All sequences formed a monophyletic tree of 2 distinct phylogroups, TH1 and TH2. Three subgroups were identified in the TH1 subgroup and were distributed in the middle region of the country. Eight subgroups of TH2 viruses were identified widely distributed throughout the country overlapping the TH1 territory. There was a correlation between human-dependent transportation routes and the distribution of virus. CONCLUSION: Inter-regional migration paths of the viruses might be correlated with translocation of dogs associated with humans. Interconnecting factors between human socioeconomic and population density might determine the transmission dynamics of virus in a rural-to-urban polarity. The presence of 2 or more rabies virus groups in a location might be indicative of a gene flow, reflecting a translocation of dogs within such region and adjacent areas. Different approaches may be required for rabies control based on the homo- or heterogeneity of the virus. Areas containing homogeneous virus populations should be targeted first. Control of dog movement associated with humans is essential

Mechanisms of escape phenomenon of spinal cord and brainstem in human rabies

BACKGROUND: Rabies virus preferentially involves brainstem, thalamus and spinal cord in human furious and paralytic rabies beginning in the early stage of illness. Nevertheless, rabies patient remains alert until the pre-terminal phase. Weakness of extremities develops only when furious rabies patient becomes comatose; whereas peripheral nerve dysfunction is responsible for weakness in paralytic rabies. METHODS: Evidence of apoptosis and mitochondrial outer membrane permeabilization in brain and spinal cord of 10 rabies patients was examined and these findings were correlated with the presence of rabies virus antigen. RESULTS: Although apoptosis was evident in most of the regions, cytochrome c leakage was relatively absent in spinal cord of nearly all patients despite the abundant presence of rabies virus antigen. Such finding was also noted in brainstem of 5 patients. CONCLUSION: Cell death in human rabies may be delayed in spinal cord and the reticular activating system, such as brainstem, thus explaining absence of weakness due to spinal cord dysfunction and preservation of consciousness