Outbreaks of H5N1 avian influenza show strong seasonality. It is not clear where the source of virus originates from in each new outbreak season. This study sought to understand the nature of viral resurgence in recent outbreak seasons in Thailand, where the epidemic is relatively well controlled. In such a situation, indigenous viruses surviving the inter-outbreak season would have to pass through a bottleneck. In order to look for evidence of the bottleneck effect, viral genome sequences from recent outbreaks in the country were analysed. H5N1 avian influenza viruses were isolated from six outbreaks in the rainy season and winter of 2007 through to early 2008. Most of the outbreaks were in the Yom-Nan River basin in the southern part of the northern region of the country. Sequences of these viral isolates were identified as clade 1, genotype Z, similar to viruses from previous years in the central region of the country. The sequences clustered into two groups, one of which was closely related to viruses isolated from the same area in July 2006. These analyses indicated that there was a strong bottleneck effect on the virus population and that only a few lineages remained in the area. In addition, evidence of reassortment among these viruses was found. These indicated re-emergence of viruses from a small pool of indigenous sources that had been silently perpetuated over the dry summer months. Therefore, an approach to eradicate H5N1 avian influenza from the area by eliminating these local reservoirs may be feasible and should be seriously considered.

Wild bird surveillance for highly pathogenic avian influenza (HPAI) H5N1 virus from 2004 to 2007 in Thailand indicated that the prevalence of infection with avian influenza H5N1 virus in wild birds was low (1.0%, 95% confidence interval [CI]: 0.7-1.2, 60/6,263 pooled samples). However, the annual prevalence varied considerably over this period, with a peak of 2.7% (95% CI: 1.4, 4.1) in 2004. Prevalence dropped to 0.5% (95% CI: 0.3, 0.8]) and 0.6% (95% CI: 0.3, 1.0) in 2005 and 2006, respectively, and then increased to 1.8% (95% CI: 1.0, 2.6) in 2007. During this period, 16 species from 12 families of wild birds tested positive for H5N1 virus infection. All samples from juvenile birds were negative for H5N1 virus, whereas 0.6% (95% CI: 0.4, 0.9) of pooled samples from adult birds were positive. Most positive samples originated from peridomestic resident species. Infected wild bird samples were only found in provinces where poultry outbreaks had occurred. Detection of H5N1 virus infection in wild birds was reported up to 3 yr after eradication of the poultry outbreaks in those provinces. As observed with outbreaks in poultry, the frequencies of H5N1 outbreaks in wild birds were significantly higher in winter. Further understanding of the mechanisms of persistence and ongoing HPAI H5N1 transmission between wild birds and domestic poultry is needed.

Lumpy skin disease (LSD) is one of the most important transboundary and emerging diseases in cattle. The disease causes significant economic losses in animal production and trade worldwide. The first LSD outbreak was recorded in March 2021, at Roi‐Et province in the northeastern region of Thailand. Thereafter, the disease had rapidly spread into neighbouring provinces and throughout the country. The aim of the present study was to provide information regarding to the molecular detection and characterization of LSD viruses from outbreaks in Thailand in 2021. There were 1,748,112 susceptible and 604,404 affected animals (n = 588,512 [36.30%], beef cattle; n = 12,367 [15.74%], dairy cattle and n = 3524 [7.35%], buffaloes). The morbidity and mortality rates were 34.57% and 3.47%, respectively, and the case fatality rate was 10.05% (60,713 deaths). Based on real‐time polymerase chain reaction results, the p32 gene of LSD virus (LSDV) was detected more frequently in skin nodule samples (54/77, 70.13%) than in nasal swabs (26/55, 42.57%) and EDTA blood (16/77, 20.78%) samples. Moreover, the copy number of the p32 gene was higher in skin nodule samples than in nasal swab and EDTA blood samples (cycle threshold value = 21.94 ± 0.62 vs. 31.52 ± 0.66 and 34.27 ± 0.32, respectively). Furthermore, 29 (53.70%) of 54 capripoxvirus‐positive skin nodule samples were successfully isolated from Madin–Darby bovine kidney cells, and the cytopathic effect was observed 72 h after inoculation. Based on the phylogenetic trees of the GPCR, ANK and RPO30 gene sequences, the LSDV isolates from Thailand were distinct from both the LSDV‐field and LSDV‐vaccine groups and were closely correlated with the LSDV strains isolated from mainland China, Hong Kong territory and Vietnam in 2020. Additionally, they could be a potential virulent vaccine‐recombinant LSDV strain.

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.

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