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Background Influenza and respiratory syncytial virus (RSV) are significant contributors to acute respiratory infections and play a substantial role in seasonal morbidity. This study sought to elucidate the clinical characteristics, seasonal trends, and genetic evolution of circulating influenza and RSV strains in Thailand during the period from 2022 to 2023. Methods Nasopharyngeal swabs were obtained from 113 patients presenting with respiratory symptoms. Laboratory confirmation identified 57 cases of influenza and 25 cases of RSV infections. Clinical and demographic data were subjected to analysis. The hemagglutinin ( HA ) and attachment glycoprotein ( G ) genes from representative strains of influenza and RSV viruses were sequenced to facilitate phylogenetic and amino acid analyses. Results Influenza cases were predominantly observed in younger adults aged 18–35 years, whereas RSV infections were distributed evenly across various age groups and were more prevalent among females. The clinical manifestations of influenza included cough, nasal congestion, sore throat, and myalgia. In contrast, RSV cases were associated with vomiting, pneumonia, bronchitis, and elevated rates of respiratory distress. The most prevalent influenza subtype was A/H3N2, accounting for 63.2% of cases, followed by A/H1N1 and B/Victoria. RSV-B was more prevalent than RSV-A, with a prevalence rate of 64.0%. The A/H3N2 strains exhibited divergence from the vaccine strain A/Darwin/9/2021, characterised by notable amino acid substitutions. Conversely, A/H1N1 strains remained closely aligned with the vaccine strains. The B/Victoria strains were categorised under the subclade V1A.3a.2 and consistently demonstrated a deletion of three amino acids in the HA gene. RSV-A isolates were identified as belonging to genotype ON1, while RSV-B isolates were classified under genotype BA9, both displaying characteristic duplications and substitutions. Conclusion This study elucidates significant distinctions in the epidemiology and clinical outcomes of influenza and RSV in Thailand during 2022–2023. Influenza, particularly the A/H3N2 subtype, was more prevalent among younger adults and exhibited genetic divergence from the recommended vaccine strain, highlighting the necessity for continuous surveillance to inform vaccine updates. Conversely, RSV affected individuals across various age groups and was associated with more severe respiratory complications, with RSV-B being predominant. The genetic profiles of influenza and RSV strains, including amino acid substitutions and lineage-specific deletions or duplications, offer valuable insights into viral evolution and immune evasion. Collectively, these findings underscore the importance of integrated clinical and molecular surveillance to inform vaccine strain selection, enhance diagnostic accuracy, and bolster public health preparedness against seasonal respiratory pathogens.

Gastrointestinal helminths are major enteric parasites affecting the health of important livestock ruminants, such as cattle and goats. It is important to routinely survey these animals for helminth infections to allow effective management and control programs to be implemented. A cross-sectional helminth survey carried out in Kanchanaburi Province, Thailand, revealed the infection rate of gastrointestinal helminths in cattle (n = 157) and goats (n = 117) to be 35.7% and 88%, respectively, by microscopic fecal examination, and a 100% herd prevalence was observed in goats. Eggs of strongyle nematodes, Strongyloides spp., Trichuris spp., Capillaria spp., Paramphistomum spp., and Moniezia spp. were detected, with a relatively high rate of strongyle nematode infection in both cattle (28.7%) and goats (86.3%). Mixed infections were observed in 14.3% and 35.9% of egg-positive samples from cattle and goats, respectively. Risk factor analysis showed that dairy cattle were 5.1 times more likely to be infected with strongyles than meat cattle. In contrast, meat goats were 9.3 times more likely to be infected with strongyles than dairy goats. The inverse findings in cattle and goats are discussed. Female gender was associated with a higher risk of strongyle infection in goats. DNA sequencing and in-house semi-nested PCR with primers specific to a region in the internal transcribed spacer 2 (ITS2) were successfully used to identify strongyle genera in randomly selected egg-positive cattle (n = 24) and goat (n = 24) samples. Four strongyle genera, i.e., Cooperia spp., Haemonchus spp., Oesophagostomum spp., and Trichostrongylus spp. were identified by DNA sequencing. By semi-nested PCR, Cooperia spp. were detected as a major parasite of cattle (70.8%), whereas Haemonchus spp. were abundant in goats (100%). The majority of samples from cattle (58.3%) and goats (95.8%) were found to coinfect with at least two strongyle genera, suggesting that coinfection with multiple strongyle genera was more common than single infection in these animals.

Metagenomics has demonstrated its capability in outbreak investigations and pathogen surveillance and discovery. With high-throughput and effective bioinformatics, many disease-causing agents, as well as novel viruses of humans and animals, have been identified using metagenomic analysis. In this study, a VIDISCA metagenomics workflow was used to identify potential unknown viruses in 33 fecal samples from asymptomatic long-tailed macaques (Macaca fascicularis) in Ratchaburi Province, Thailand. Putatively novel astroviruses, enteroviruses, and adenoviruses were detected and confirmed by PCR analysis of long-tailed macaque fecal samples collected from areas in four provinces, Ratchaburi, Kanchanaburi, Lopburi, and Prachuap Khiri Khan, where humans and monkeys live in proximity (total n = 187). Astroviruses, enteroviruses, and adenoviruses were present in 3.2%, 7.5%, and 4.8% of macaque fecal samples, respectively. One adenovirus, named AdV-RBR-6-3, was successfully isolated in human cell culture. Whole-genome analysis suggested that it is a new member of the species Human adenovirus G, closely related to Rhesus adenovirus 53, with evidence of genetic recombination and variation in the hexon, fiber, and CR1 genes. Sero-surveillance showed neutralizing antibodies against AdV-RBR-6-3 in 2.9% and 11.2% of monkeys and humans, respectively, suggesting cross-species infection of monkeys and humans. Overall, we reported the use of metagenomics to screen for possible new viruses, as well as the isolation and molecular and serological characterization of the new adenovirus with cross-species transmission potential. The findings emphasize that zoonotic surveillance is important and should be continued, especially in areas where humans and animals interact, to predict and prevent the threat of emerging zoonotic pathogens.

After publication of the article, the authors received comments from a member of the Viruses editorial board who is an expert in the field of adenovirus concerning figures and references that should be included in the paper [...]

Background Relapse infections resulting from the activation hypnozoites produced by Plasmodium vivax and Plasmodium ovale represent an important obstacle to the successful control of these species. A single licensed drug, primaquine is available to eliminate these liver dormant forms. To date, investigations of vivax relapse infections have been few in number. Results Genotyping, based on polymorphic regions of two genes ( Pvmsp1 F3 and Pvcsp ) and four microsatellite markers (MS3.27, MS3.502, MS6 and MS8), of 12 paired admission and relapse samples from P. vivax -infected patients were treated with primaquine, revealed that in eight of the parasite populations in the admission and relapse samples were homologous, and heterologous in the remaining four patients. The patients’ CYP2D6 genotypes did not suggest that any were poor metabolisers of primaquine. Parasitaemia tended to be higher in the heterologous as compared to the homologous relapse episodes as was the IgG3 response. For the twelve pro- and anti-inflammatory cytokine levels measured for all samples, only those of IL-6 and IL-10 tended to be higher in patients with heterologous as compared to homologous relapses in both admission and relapse episodes. Conclusions The data from this limited number of patients with confirmed relapse episodes mirror previous observations of a significant proportion of heterologous parasites in relapses of P. vivax infections in Thailand. Failure of the primaquine treatment that the patients received is unlikely to be due to poor drug metabolism, and could indicate the presence of P. vivax populations in Thailand with poor susceptibility to 8-aminoquinolines.

Entomological surveillance for arthropod-borne viruses is vital for monitoring vector-borne diseases and informing vector control programs. In this study, we conducted entomological surveillance in Zika virus endemic areas. In Thailand, it is standard protocol to perform mosquito control within 24 h of a reported dengue case. Aedes females were collected within 72 h of case reports from villages with recent Zika–human cases in Kamphaeng Phet Province, Thailand in 2017 and 2018. Mosquitoes were bisected into head-thorax and abdomen and then screened for Zika (ZIKV) and dengue (DENV) viruses using real-time RT-PCR. ZIKV RNA was detected in three samples from two female Ae. aegypti (1.4%). A partial envelope sequence analysis revealed that the ZIKV sequences were the Asian lineage identical to sequences from ZIKV-infected cases reported in Thailand during 2016 and 2017. Dengue virus-1 (DENV-1) and dengue virus-4 (DENV-4) were found in four Ae. aegypti females (2.8%), and partial capsid sequences were nearly identical with DENV-1 and DENV-4 from Thai human cases reported in 2017. Findings in the current study demonstrate the importance of entomological surveillance programs to public health mosquito-borne disease prevention measures and control.

Duffy binding protein region II of Plasmodium vivax (PvDBPII) is a key target for vaccine-mediated immunity despite its highly polymorphic nature. Genetic diversity of PvDBPII within and between P. vivax isolates vary according to geographic regions, which might affect host immune response. This study evaluated DBPII allelic variations and naturally acquired immunity in P. vivax-infected individuals from malaria endemic areas of Thailand. Twenty-three 15-mer DBP peptides (DBPps) covering a critical binding motif in PvDBPII of P. vivax Thai isolates were evaluated for their immunogenicity in P. vivax-infected individuals (n = 82) compared to healthy non-parasite exposed controls (n = 39). Eighty-seven percent P. vivax-infected individuals had significantly higher anti-PvDBPII total IgG against six DBPps compared to controls. Anti-PvDBPII IgG1 was the most prominent subclass. Low IgG3 levels against Thai P. vivaxspecific DBPp4 and DBPp5 and non-polymorphic DBPp22 were also detected. High IgG1 and low IgG3 response to DBPp4 and DBPp5 were associated with DBPp4 L333F (CTT>TTT) and DBPp5 S351C (AGT>TGT) mutations, in which the point mutation was C/A>T, whereas T/C>A/C mutation was present in other DBPps. These preliminary data revealed variations in levels of anti-PvDBPII IgG subclasses in P. vivax-infected individuals, which might impact vaccine development strategies against vivax malaria.

Metagenomics has demonstrated its capability in outbreak investigations and pathogen surveillance and discovery. With high-throughput and effective bioinformatics, many disease-causing agents, as well as novel viruses of humans and animals, have been identified using metagenomic analysis. In this study, a VIDISCA metagenomics workflow was used to identify potential unknown viruses in 33 fecal samples from asymptomatic long-tailed macaques ( ) in Ratchaburi Province, Thailand. Putatively novel astroviruses, enteroviruses, and adenoviruses were detected and confirmed by PCR analysis of long-tailed macaque fecal samples collected from areas in four provinces, Ratchaburi, Kanchanaburi, Lopburi, and Prachuap Khiri Khan, where humans and monkeys live in proximity (total = 187). Astroviruses, enteroviruses, and adenoviruses were present in 3.2%, 7.5%, and 4.8% of macaque fecal samples, respectively. One adenovirus, named AdV-RBR-6-3, was successfully isolated in human cell culture. Whole-genome analysis suggested that it is a new member of the species , closely related to Rhesus adenovirus 53, with evidence of genetic recombination and variation in the hexon, fiber, and CR1 genes. Sero-surveillance showed neutralizing antibodies against AdV-RBR-6-3 in 2.9% and 11.2% of monkeys and humans, respectively, suggesting cross-species infection of monkeys and humans. Overall, we reported the use of metagenomics to screen for possible new viruses, as well as the isolation and molecular and serological characterization of the new adenovirus with cross-species transmission potential. The findings emphasize that zoonotic surveillance is important and should be continued, especially in areas where humans and animals interact, to predict and prevent the threat of emerging zoonotic pathogens.

Background Knowledge of the population genetics and transmission dynamics of Plasmodium vivax is crucial in predicting the emergence of drug resistance, relapse pattern and novel parasite phenotypes, all of which are relevant to the control of vivax infections. The aim of this study was to analyse changes in the genetic diversity of P. vivax genes from field isolates collected at different times along the Thai–Myanmar border. Methods Two hundred and fifty-four P. vivax isolates collected during two periods 10 years apart along the Thai–Myanmar border were analysed. The parasites were genotyped by nested-PCR and PCR–RFLP targeting selected polymorphic loci of Pvmsp1 , Pvmsp3α and Pvcsp genes. Results The total number of distinguishable allelic variants observed for Pvcsp , Pvmsp1 , and Pvmsp3α was 17, 7 and 3, respectively. High genetic diversity was observed for Pvcsp ( H E  = 0.846) and Pvmsp1 ( H E  = 0.709). Of the 254 isolates, 4.3 and 14.6 % harboured mixed Pvmsp1 and Pvcsp genotypes with a mean multiplicity of infection (MOI) of 1.06 and 1.15, respectively. The overall frequency of multiple genotypes was 16.9 %. When the frequencies of allelic variants of each gene during the two distinct periods were analysed, significant differences were noted for Pvmsp1 ( P  = 0.018) and the Pvcsp ( P  = 0.033) allelic variants. Conclusion Despite the low malaria transmission levels in Thailand, P. vivax population exhibit a relatively high degree of genetic diversity along the Thai–Myanmar border of Thailand, in particular for Pvmsp1 and Pvcsp , with indication of geographic and temporal variation in frequencies for some variants. These results are of relevance to monitoring the emergence of drug resistance and to the elaboration of measures to control vivax malaria.