Severe fever with thrombocytopenia syndrome (SFTS) in Thailand: using a one health approach to respond to novel zoonosis and its implications in clinical practice.

Severe fever with thrombocytopenia syndrome (SFTS), a tick-borne disease caused by Dabie bandavirus (SFTSV) is an emerging infectious disease of substantial concern in East Asia. In 2019, Ongkittikul S et al. reported the first case of SFTS in Thailand. Our report describes a One Health investigation of SFTS zoonosis examining the index case and suspected animal reservoirs using real-time RT-PCR and immunoassays. We add to the report on the first confirmed case of SFTSV infection in a human in Thailand by conducting a limited but informative One Health surveillance study. Dogs and cats tested positive for SFTSV antibody using IgG ELISA. We conclude that domestic dogs and cats might serve as potential reservoirs for SFTSV spread due to their closer proximity to the index case than other non-domestic animals. Notably, we did not detect SFTSV in synanthropic cats or dogs-nor did we detect SFTSV in Rhipicephalus sanguineus ticks-using RT-PCR. We propose that One Health investigations coupling genomic and serologic assays in response to new SFTS cases could play a pivotal role in preventing and managing SFTS among humans and animals in East Asia. As such, we are establishing a collaborative response to SFTS in Thailand through human outbreak investigations that align with principles of One Health, through environmental surveys and animal RT-PCR and immunoassays. Our investigation highlights the importance of coupling RT-PCR with seroprevalence assays as principal elements of One Health surveillance for SFTS in order to shed light on potential animal reservoirs and track emerging zoonosis.

Alpha and gamma mangostins inhibit wild-type B SARS-CoV-2 more effectively than the SARS-CoV-2 variants and the major target is unlikely the 3C-like protease.

Background: Anti-SARS-CoV-2 and immunomodulatory drugs are important for treating clinically severe patients with respiratory distress symptoms. Alpha- and gamma-mangostins (AM and GM) were previously reported as potential 3C-like protease (3CLpro) and Angiotensin-converting enzyme receptor 2 (ACE2)-binding inhibitors in silico. Objective: We aimed to evaluate two active compounds, AM and GM, from Garcinia mangostana for their antivirals against SARS-CoV-2 in live virus culture systems and their cytotoxicities using standard methods. Also, we aimed to prove whether 3CLpro and ACE2 neutralization were major targets and explored whether any additional targets existed. Methods: We tested the translation and replication efficiencies of SARS-CoV-2 in the presence of AM and GM. Initial and subgenomic translations were evaluated by immunofluorescence of SARS-CoV-2 3CLpro and N expressions at 16 h after infection. The viral genome was quantified and compared with the untreated group. We also evaluated the efficacies and cytotoxicities of AM and GM against four strains of SARS-CoV-2 (wild-type B, B.1.167.2, B.1.36.16, and B.1.1.529) in Vero E6 cells. The potential targets were evaluated using cell-based anti-attachment, time-of-drug addition, in vitro 3CLpro activities, and ACE2-binding using a surrogated viral neutralization test (sVNT). Moreover, additional targets were explored using combinatorial network-based interactions and Chemical Similarity Ensemble Approach (SEA). Results: AM and GM reduced SARS-CoV-2 3CLpro and N expressions, suggesting that initial and subgenomic translations were globally inhibited. AM and GM inhibited all strains of SARS-CoV-2 at EC50 of 0.70-3.05 µM, in which wild-type B was the most susceptible strain (EC50 0.70-0.79 µM). AM was slightly more efficient in the variants (EC50 0.88-2.41 µM), resulting in higher selectivity indices (SI 3.65-10.05), compared to the GM (EC50 0.94-3.05 µM, SI 1.66-5.40). GM appeared to be more toxic than AM in both Vero E6 and Calu-3 cells. Cell-based anti-attachment and time-of-addition suggested that the potential molecular target could be at the post-infection. 3CLpro activity and ACE2 binding were interfered with in a dose-dependent manner but were insufficient to be a major target. Combinatorial network-based interaction and chemical similarity ensemble approach (SEA) suggested that fatty acid synthase (FASN), which was critical for SARS-CoV-2 replication, could be a target of AM and GM. Conclusion: AM and GM inhibited SARS-CoV-2 with the highest potency at the wild-type B and the lowest at the B.1.1.529. Multiple targets were expected to integratively inhibit viral replication in cell-based system.

Identification of common human infectious and potentially zoonotic novel genotypes of Enterocytozoon bieneusi in cavernicolous bats in Thailand.

Enterocytozoon bieneusi is a common cause of human microsporidiosis and can infect a variety of animal hosts worldwide. In Thailand, previous studies have shown that this parasite is common in domestic animals. However, information on the prevalence and genotypes of this parasite in other synanthropic wildlife, including bats, remains limited. Several pathogens have been previously detected in bats, suggesting that bats may serve as a reservoir for this parasite. In this study, a total of 105 bat guano samples were collected from six different sites throughout Thailand. Of these, 16 from Chonburi (eastern), Ratchaburi (western), and Chiang Rai (northern) provinces tested positive for E. bieneusi, representing an overall prevalence of 15.2%. Based on ITS1 sequence analysis, 12 genotypes were identified, including two known genotypes (D and type IV) frequently detected in humans and ten novel potentially zoonotic genotypes (TBAT01-TBAT10), all belonging to zoonotic group 1. Lyle's flying fox (Pteropus lylei), commonly found in Southeast Asia, was identified as the host in one sample that was also positive for E. bieneusi. Network analysis of E. bieneusi sequences detected in this study and those previously reported in Thailand also revealed intraspecific divergence and recent population expansion, possibly due to adaptive evolution associated with host range expansion. Our data revealed, for the first time, multiple E. bieneusi genotypes of zoonotic significance circulating in Thai bats and demonstrated that bat guano fertilizer may be a vehicle for disease transmission.

Comparative Performance in the Detection of Four Coronavirus Genera from Human, Animal, and Environmental Specimens.

Emerging coronaviruses (CoVs) are understood to cause critical human and domestic animal diseases; the spillover from wildlife reservoirs can result in mild and severe respiratory illness in humans and domestic animals and can spread more readily in these naïve hosts. A low-cost CoV molecular method that can detect a variety of CoVs from humans, animals, and environmental specimens is an initial step to ensure the early identification of known and new viruses. We examine a collection of 50 human, 46 wastewater, 28 bat, and 17 avian archived specimens using 3 published pan-CoV PCR assays called Q-, W-, and X-CoV PCR, to compare the performance of each assay against four CoV genera. X-CoV PCR can detect all four CoV genera, but Q- and W-CoV PCR failed to detect δ-CoV. In total, 21 (42.0%), 9 (18.0%), and 21 (42.0%) of 50 human specimens and 30 (65.22%), 6 (13.04%), and 27 (58.70%) of 46 wastewater specimens were detected using Q-, W-, and X-CoV PCR assays, respectively. The X-CoV PCR assay has a comparable sensitivity to Q-CoV PCR in bat CoV detection. Combining Q- and X-CoV PCR assays can increase sensitivity and avoid false negative results in the early detection of novel CoVs.

An unusual diarrheal outbreak in the community in Eastern Thailand caused by Norovirus GII.3[P25].

BACKGROUND: Sentinel laboratory surveillance for diarrheal disease determined norovirus to be the most common cause of non-bacterial gastroenteritis in people during the COVID-19 pandemic in Thailand. An increase in patients presenting with diarrhea and vomiting in hospitals across Chanthaburi province between December 2021 and January 2022 led to the need for the identification of viral pathogens that may be responsible for the outbreak. METHODS: Fecal samples (rectal swabs or stool) from 93 patients, of which 65 patients were collected during the December 2021 to January 2022 outbreak, were collected and screened for viral infection by real-time RT-PCR. Positive samples for norovirus GII were then genotyped by targeted amplification and sequencing of partial polymerase and capsid genes. Full genome sequencing was performed from the predominant strain, GII.3[P25]. RESULTS: Norovirus was the most common virus detected in human fecal samples in this study. 39 of 65 outbreak samples (60%) and 3 of 28 (10%) non-outbreak samples were positive for norovirus genogroup II. One was positive for rotavirus, and one indicated co-infection with rotavirus and norovirus genogroups I and II. Nucleotide sequences of VP1 and RdRp gene were successfully obtained from 28 of 39 positive norovirus GII and used for dual-typing; 25/28 (89.3%) were GII.3, and 24/28 (85.7) were GII.P25, respectively. Norovirus GII.3[P25] was the predominant strain responsible for this outbreak. The full genome sequence of norovirus GII.3[P25] from our study is the first reported in Thailand and has 98.62% and 98.57% similarity to norovirus found in China in 2021 and the USA in 2022, respectively. We further demonstrate the presence of multiple co-circulating norovirus genotypes, including GII.21[P21], GII.17[P17], GII.3[P12] and GII.4[P31] in our study. CONCLUSIONS: An unusual diarrhea outbreak was found in December 2021 in eastern Thailand. Norovirus strain GII.3[P25] was the cause of the outbreak and was first detected in Thailand. The positive rate during GII.3[P25] outbreak was six times higher than sporadic cases (GII.4), and, atypically, adults were the primary infected population rather than children.

High Transmission Rates of Early Omicron Subvariant BA.2 in Bangkok, Thailand.

The emergence of Omicron as the fifth variant of concern within the SARS-CoV-2 pandemic in late 2021, characterized by its rapid transmission and distinct spike gene mutations, underscored the pressing need for cost-effective and efficient methods to detect viral variants, especially given their evolving nature. This study sought to address this need by assessing the effectiveness of two SARS-CoV-2 variant classification platforms based on RT-PCR and mass spectrometry. The primary aim was to differentiate between Delta, Omicron BA.1, and Omicron BA.2 variants using 618 COVID-19-positive samples collected from Bangkok patients between November 2011 and March 2022. The analysis revealed that both BA.1 and BA.2 variants exhibited significantly higher transmission rates, up to 2-3 times, when compared to the Delta variant. This research presents a cost-efficient approach to virus surveillance, enabling a quantitative evaluation of variant-specific public health implications, crucial for informing and adapting public health strategies.

Genetic diversity and phylogenetic analyses of Asian lineage Zika virus whole genome sequences derived from Culex quinquefasciatus mosquitoes and urine of patients during the 2020 epidemic in Thailand.

Zika virus (ZIKV), a mosquito-borne flavivirus, has been continually emerging and re-emerging since 2010, with sporadic cases reported annually in Thailand, peaking at over 1000 confirmed positive cases in 2016. Leveraging high-throughput sequencing technologies, specifically whole genome sequencing (WGS), has facilitated rapid pathogen genome sequencing. In this study, we used multiplex amplicon sequencing on the Illumina Miseq instrument to describe ZIKV WGS. Six ZIKV WGS were derived from three samples of field-caught Culex quinquefasciatus mosquitoes (two males and one female) and three urine samples collected from patients in three different provinces of Thailand. Additionally, successful isolation of a ZIKV isolate occurred from a female Cx. quinquefasciatus. The WGS analysis revealed a correlation between the 2020 outbreak and the acquisition of five amino acid changes in the Asian lineage ZIKV strains from Thailand (2006), Cambodia (2010 and 2019), and the Philippines (2012). These changes, including C-T106A, prM-V1A, E-V473M, NS1-A188V, and NS5-M872V, were identified in all seven WGS, previously linked to significantly higher mortality rates. Furthermore, phylogenetic analysis indicated that the seven ZIKV sequences belonged to the Asian lineage. Notably, the genomic region of the E gene showed the highest nucleotide diversity (0.7-1.3%). This data holds significance in informing the development of molecular tools that enhance our understanding of virus patterns and evolution. Moreover, it may identify targets for improved methods to prevent and control future ZIKV outbreaks.

Long-term immunogenicity in previously vaccinated healthcare workers with inactivated virus vaccine after SARS-CoV-2 infection or booster vaccination.

Immunity against SARS-CoV-2 infection in vaccinated individuals varies based on the vaccine type, duration after vaccination or infection, and SARS-CoV-2 variant type. We conducted a prospective observational study to evaluate the immunogenicity of a booster vaccination with AZD1222 after two doses of CoronaVac (booster group) compared to individuals who had SARS-CoV-2 infection after receiving two doses of CoronaVac (infection group). We used a surrogate virus neutralization test (sVNT) to evaluate immunity against wild-type and Omicron variant (BA.1) at 3 and 6 months after infection or booster dose. Of the 89 participants, 41 were in the infection group, and 48 were in the booster group. At 3 months post-infection or booster vaccination, the median (IQR) sVNT against wild-type was 97.87 % (97.57-97.93 %) and 97.65 % (95.38-98.00 %), p = 0.66, respectively, while the sVNT against Omicron was 18.8 % (0-47.10 %) and 24.46 (11.69-35.47 %), p = 0.72 respectively. At 6 months, the median (IQR) sVNT against wild-type was 97.68 % (95.86-97.92 %) in the infection group, higher than 94.7 % (95.38-98.00 %) in the booster group (p = 0.03). Results showed no significant difference in immunity against wild-type and Omicron at 3 months between the two groups. However, the infection group exhibited better immunity than the booster group at 6 months.

SARS-CoV-2 Variants Detection Strategies in Wastewater Samples Collected in the Bangkok Metropolitan Region.

Wastewater surveillance is considered a promising approach for COVID-19 surveillance in communities. In this study, we collected wastewater samples between November 2020 and February 2022 from twenty-three sites in the Bangkok Metropolitan Region to detect the presence of SARS-CoV-2 and its variants for comparison to standard clinical sampling. A total of 215 wastewater samples were collected and tested for SARS-CoV-2 RNA by real-time PCR with three targeted genes (N, E, and ORF1ab); 102 samples were positive (42.5%). The SARS-CoV-2 variants were determined by a multiplex PCR MassARRAY assay to distinguish four SARS-CoV-2 variants, including Alpha, Beta, Delta, and Omicron. Multiple variants of Alpha-Delta and Delta-Omicron were detected in the wastewater samples in July 2021 and January 2022, respectively. These wastewater variant results mirrored the country data from clinical specimens deposited in GISAID. Our results demonstrated that wastewater surveillance using multiple signature mutation sites for SARS-CoV-2 variant detection is an appropriate strategy to monitor the presence of SARS-CoV-2 variants in the community at a low cost and with rapid turn-around time. However, it is essential to note that sequencing surveillance of wastewater samples should be considered complementary to whole genome sequencing of clinical samples to detect novel variants.

Simultaneous detection of omicron and other SARS-CoV-2 variants by multiplex PCR MassARRAY technology.

The rapid emergence of SARS-CoV-2 variants with high severity and transmutability adds further urgency for rapid and multiplex molecular testing to identify the variants. A nucleotide matrix-assisted laser-desorption-ionization time-of-flight mass spectrophotometry (MALDI-TOF MS)-based assay was developed (called point mutation array, PMA) to identify four major SARS-CoV-2 variants of concern (VOCs) including Alpha, Beta, Delta, and Omicron (namely PMA-ABDO) and differentiate Omicron subvariant (namely PMA-Omicron). PMA-ABDO and PMA-Omicron consist of 24 and 28 mutation sites of the spike gene. Both PMA panels specifically identified VOCs with as low as 10 viral copies/µl. The panel has shown a 100% concordant with the Next Generation Sequencing (NGS) results testing on 256 clinical specimens with real-time PCR cycle threshold (Ct) values less than 26. It showed a higher sensitivity over NGS; 25/28 samples were positive by PMA but not NGS in the clinical samples with PCR Ct higher than 26. Due to the mass of nucleotide used to differentiate between wild-type and mutation strains, the co-infection or recombination of multiple variants can be determined by the PMA method. This method is flexible in adding a new primer set to identify a new emerging mutation site among the current circulating VOCs and the turnaround time is less than 8 h. However, the spike gene sequencing or NGS retains the advantage of detecting newly emerged variants.

Description of potential vectors of zoonotic filarial nematodes, Brugia pahangi, Setaria digitata, and Setaria labiatopapillosa in Thai mosquitoes.

Filariasis is classified as a vector-borne zoonotic disease caused by several filarial nematodes. The disease is widely distributed in tropical and subtropical regions. Understanding the relationship between mosquito vectors, filarial parasites, and vertebrate hosts is therefore essential for determining the probability of disease transmission and, correspondingly, developing effective strategies for prevention and control of diseases. In this study, we aimed to investigate the infection of zoonotic filarial nematodes in field-caught mosquitoes, observe the potential vectors of filaria parasites in Thailand using a molecular-based survey, conduct a study of host-parasite relationship, and propose possible coevolution of the parasites and their hosts. Mosquitoes were collected around cattle farms in Bangkok, Nakhon Si Thammarat, Ratchaburi, and Lampang provinces from May to December 2021 using a CDC Backpack aspirator for 20-30 minutes in each area (intra-, peri-, and wild environment). All mosquitoes were identified and morphologically dissected to demonstrate the live larvae of the filarial nematode. Furthermore, all samples were tested for filarial infections using PCR and sequencing. A total of 1,273 adult female mosquitoes consisted of five species: 37.78% Culex quinquefasciatus, 22.47% Armigeres subalbatus, 4.71% Cx. tritaeniorhynchus, 19.72% Anopheles peditaeniatus, and 15.32% An. dirus. Larvae of Brugia pahangi and Setaria labiatopapillosa were found in Ar. subalbatus and An. dirus mosquitoes, respectively. All mosquito samples were processed by PCR of ITS1 and COXI genes for filaria nematode species identification. Both genes showed that B. pahangi was found in four mosquitoes of Ar. subalbatus from Nakhon Si Thammarat, S. digitata was detected in three samples of An. peditaeniatus from Lampang, and S. labiatopapillosa was detected in one of An. dirus from Ratchaburi. However, filarial nematodes were not found in all Culex species. This study infers that this is the first data regarding the circulation of Setaria parasites in Anopheles spp. from Thailand. The phylogenetic trees of the hosts and parasites are congruent. Moreover, the data could be used to develop more effective prevention and control strategies for zoonotic filarial nematodes before they spread in Thailand.

Simultaneous Detection of Omicron and Other SARS-CoV-2 Variants by Multiplex PCR MassARRAY Technology.

The rapid emergence of SARS-CoV-2 variants with high severity and transmutability adds further urgency for rapid and multiplex molecular testing to identify the variants. A nucleotide matrix-assisted laser-desorption-ionization time-of-flight mass spectrophotometry (MALDI-TOF MS)-based assay was developed (called point mutation array, PMA) to identify four major SARS-CoV-2 variants of concern (VOCs) including Alpha, Beta, Delta, and Omicron (namely PMA-ABDO) and differentiate Omicron subvariant (namely PMA-Omicron). PMA-ABDO and PMA-Omicron consist of 24 and 28 mutation sites of the spike gene. Both PMA panels specifically identified VOCs with as low as 10 viral copies/ µl. The panel has shown a 100% concordant with the Next Generation Sequencing (NGS) results testing on 256 clinical specimens with real-time PCR cycle threshold (Ct) values less than 26. It showed a higher sensitivity over NGS; 25/28 samples were positive by PMA but not NGS in the clinical samples with PCR Ct higher than 26. Due to the mass of nucleotide used to differentiate between wild-type and mutation strains, the co-infection or recombination of multiple variants can be determined by the PMA method. This method is flexible in adding a new primer set to identify a new emerging mutation site among the current circulating VOCs and the turnaround time is less than 8 hours. However, the spike gene sequencing or NGS retains the advantage of detecting newly emerged variants.

SARS-CoV-2 Omicron variant emerged under immune selection.

The SARS-CoV-2 Omicron variant (B.1.1.529 lineage) escapes antibodies that neutralize the ancestral virus. We tested human serum panels from participants with differing infection and vaccination status using a multiplex surrogate virus neutralization assay targeting 20 sarbecoviruses. We found that bat and pangolin sarbecoviruses showed significantly less neutralization escape than the Omicron variant. We propose that SARS-CoV-2 variants have emerged under immune selection pressure and are evolving differently from animal sarbecoviruses.

Pandemic origins and a One Health approach to preparedness and prevention: Solutions based on SARS-CoV-2 and other RNA viruses.

COVID-19 is the latest zoonotic RNA virus epidemic of concern. Learning how it began and spread will help to determine how to reduce the risk of future events. We review major RNA virus outbreaks since 1967 to identify common features and opportunities to prevent emergence, including ancestral viral origins in birds, bats, and other mammals; animal reservoirs and intermediate hosts; and pathways for zoonotic spillover and community spread, leading to local, regional, or international outbreaks. The increasing scientific evidence concerning the origins of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is most consistent with a zoonotic origin and a spillover pathway from wildlife to people via wildlife farming and the wildlife trade. We apply what we know about these outbreaks to identify relevant, feasible, and implementable interventions. We identify three primary targets for pandemic prevention and preparedness: first, smart surveillance coupled with epidemiological risk assessment across wildlife-livestock-human (One Health) spillover interfaces; second, research to enhance pandemic preparedness and expedite development of vaccines and therapeutics; and third, strategies to reduce underlying drivers of spillover risk and spread and reduce the influence of misinformation. For all three, continued efforts to improve and integrate biosafety and biosecurity with the implementation of a One Health approach are essential. We discuss new models to address the challenges of creating an inclusive and effective governance structure, with the necessary stable funding for cross-disciplinary collaborative research. Finally, we offer recommendations for feasible actions to close the knowledge gaps across the One Health continuum and improve preparedness and response in the future.

Development and evaluation of a visible reverse transcription-loop-mediated isothermal amplification (RT-LAMP) for the detection of Asian lineage ZIKV in field-caught mosquitoes.

The Zika virus (ZIKV) infection is an emerging and re-emerging arbovirus infection that is transmitted to humans through the bite of infected mosquitoes. Early detection of ZIKV in mosquitoes is one of the prerequisite approaches for tracking the spread of the virus. Therefore, this study aims to develop and validate a visual reverse transcription-loop-mediated isothermal amplification (RT-LAMP) method called ZIKV-RT-LAMP, for detecting ZIKV in field collected mosquito samples from Thailand. A single-tube ZIKV-RT-LAMP assay was developed to detect Asian lineage ZIKV RNA. The detection limit and cross-reactivity of ZIKV were investigated. The hemi-nested RT-PCR (hn-RT-PCR) and the colorimetric LAMP kit (cLAMP kit) were performed as reference assays. The detection limit of the ZIKV-RT-LAMP assay was 10-6 ffu/ml or pfu/ml, making it highly specific and 100 times more sensitive than the hn-RT-PCR and cLAMP kits. The ZIKV-RT-LAMP assay detected the Asian lineage of ZIKV RNA without cross-reactivity with other arthropod-borne viruses. The sensitivity and specificity of the ZIKV-RT-LAMP assay were 92.31% and 100%, respectively. The ZIKV-RT-LAMP is a simple, rapid, and inexpensive method for detecting ZIKV in field-caught mosquitos. In the future, extensive surveys of field-caught mosquito populations should be conducted. Early detection of ZIKV in field-caught mosquitoes provides for prompt and effective implementation of mosquito control strategies in endemic areas.

Homologous or Heterologous COVID-19 Booster Regimens Significantly Impact Sero-Neutralization of SARS-CoV-2 Virus and Its Variants.

We determined the levels of neutralizing antibodies against the SARS-CoV-2 ancestral strain, Delta and Omicron variants of concern (VOCs), in 125 healthcare workers who received CoronaVac as their primary vaccination and later received either a single ChAdOx1 or a combi-nation of two consecutive boosters using either two ChAdOx1 doses or a ChAdOx1 or BNT162b2 as the primary and second boosters, respectively, or two doses of BNT162b2. The titers 12 weeks after primary vaccination were inadequate to neutralize all strains. After a single ChAdOx1 booster, the levels of neutralization at Day 30 varied significantly, with only a small proportion of participants developing neutralizing titers against Omicron at Day 7 and 30. The two doses of ChAdOx1 as the booster induced the lowest activity. A combination ChAdOx1 and BNT162b2 induced greater neutralization than by two doses of ChAdOx1. Two doses of BNT162b2 as the booster had the maximal activity against Omicron VOC.

Mapping Risk of Nipah Virus Transmission from Bats to Humans in Thailand.

Nipah virus (NiV) is a zoonotic virus that can pose a serious threat to human and livestock health. Old-world fruit bats (Pteropus spp.) are the natural reservoir hosts for NiV, and Pteropus lylei, Lyle's flying fox, is an important host of NiV in mainland Southeast Asia. NiV can be transmitted from bats to humans directly via bat-contaminated foods (i.e., date palm sap or fruit) or indirectly via livestock or other intermediate animal hosts. Here we construct risk maps for NiV spillover and transmission by combining ecological niche models for the P. lylei bat reservoir with other spatial data related to direct or indirect NiV transmission (livestock density, foodborne sources including fruit production, and human population). We predict the current and future (2050 and 2070) distribution of P. lylei across Thailand, Cambodia, and Vietnam. Our best-fit model predicted that central and western regions of Thailand and small areas in Cambodia are currently the most suitable habitats for P. lylei. However, due to climate change, the species range is predicted to expand to include lower northern, northeastern, eastern, and upper southern Thailand and almost all of Cambodia and lower southern Vietnam. This expansion will create additional risk areas for human infection from P. lylei in Thailand. Our combined predictive risk maps showed that central Thailand, inhabited by 2.3 million people, is considered highly suitable for the zoonotic transmission of NiV from P. lylei. These current and future NiV transmission risk maps can be used to prioritize sites for active virus surveillance and developing awareness and prevention programs to reduce the risk of NiV spillover and spread in Thailand.

Use of qRT-PCR for SARS-CoV-2 sgRNA leader for the therapeutic plan: a preliminary report on 10 patients.

INTRODUCTION: Duration of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) shedding is important for infection control. The presence of SARS-CoV-2 subgenomic RNA (sgRNA) leader indicates that the virus is replicative. This study examined the shedding duration of SARS-CoV-2 sgRNA leader and genomic RNA (gRNA) in diverse respiratory specimens. METHODOLOGY: One hundred and eleven respiratory specimens collected sequentially from 10 COVID-19 patients with real-time RT-PCR SARS-CoV-2 orf1ab gene confirmed positive admitted to King Chulalongkorn Memorial Hospital were examined for SARS-CoV-2 E sgRNA leader and E gRNA by using Real-time reverse transcription PCR (qRT-PCR). These specimens included nasopharyngeal swab and throat swabs, nasal swab and throat swabs, sputum, and endotracheal aspirate, and were collected from the first day of admission until the time of orf1ab real-time RT-PCR negative of at least 2-4 consecutive days. RESULTS: E sgRNA leader could only be detectable in specimens with ≥ 1E+05 virus E gene copies per ml within the first 15 days after hospitalization. SARS-CoV-2 sgRNA leader was undetectable from one to 15 days earlier than that of gRNA in all patients. Re-shedding of sgRNA was evident in 2 cases, both on a single occasion after being undetectable for 3-10 days. CONCLUSIONS: Assessment of the presence of sgRNA leader may be useful for therapeutic planning.

Dynamics of Neutralizing Antibody and T-Cell Responses to SARS-CoV-2 and Variants of Concern after Primary Immunization with CoronaVac and Booster with BNT162b2 or ChAdOx1 in Health Care Workers.

Inactivated SARS-CoV-2 vaccine (CoronaVac) is commonly used in national immunization programs. However, the immune response significantly declines within a few months. Our study assessed the immune response against SARS-CoV-2 after receiving booster shots of BNT162b2 or ChAdOx1 among health care workers who previously received CoronaVac as their primary immunization. Fifty-six participants who received ChAdOx1 and forty-two participants who received BNT162b2 were enrolled into this study, which evaluated immune responses, including anti-SARS-CoV-2 spike total antibodies (Elecsys®), surrogated viral neutralization test (sVNT) to ancestral strain (cPass™; GenScript), five variants of concern (Alpha, Beta, Gamma, Delta, and Omicron) (Luminex; multiplex sVNT) and the ELISpot with spike (S1 and S2) peptide pool against the ancestral SARS-CoV-2 strain. The samples were analyzed at baseline, 4, and 12 weeks after primary immunization, as well as 4 and 12 weeks after receiving the booster. This study showed a significant increase in anti-SARS-CoV-2 spike total antibodies, sVNT, and T-cell immune response after the booster, including against the Omicron variant. Immune responses rapidly decreased in the booster group at 12 weeks after booster but were still higher than post-primary vaccination. A fourth dose or a second booster should be recommended, particularly in health care workers.

Behavioral-biological surveillance of emerging infectious diseases among a dynamic cohort in Thailand.

BACKGROUND: Interactions between humans and animals are the key elements of zoonotic spillover leading to zoonotic disease emergence. Research to understand the high-risk behaviors associated with disease transmission at the human-animal interface is limited, and few consider regional and local contexts. OBJECTIVE: This study employed an integrated behavioral-biological surveillance approach for the early detection of novel and known zoonotic viruses in potentially high-risk populations, in an effort to identify risk factors for spillover and to determine potential foci for risk-mitigation measures. METHOD: Participants were enrolled at two community-based sites (n = 472) in eastern and western Thailand and two hospital (clinical) sites (n = 206) in northeastern and central Thailand. A behavioral questionnaire was administered to understand participants' demographics, living conditions, health history, and animal-contact behaviors and attitudes. Biological specimens were tested for coronaviruses, filoviruses, flaviviruses, influenza viruses, and paramyxoviruses using pan (consensus) RNA Virus assays. RESULTS: Overall 61/678 (9%) of participants tested positive for the viral families screened which included influenza viruses (75%), paramyxoviruses (15%), human coronaviruses (3%), flaviviruses (3%), and enteroviruses (3%). The most salient predictors of reporting unusual symptoms (i.e., any illness or sickness that is not known or recognized in the community or diagnosed by medical providers) in the past year were having other household members who had unusual symptoms and being scratched or bitten by animals in the same year. Many participants reported raising and handling poultry (10.3% and 24.2%), swine (2%, 14.6%), and cattle (4.9%, 7.8%) and several participants also reported eating raw or undercooked meat of these animals (2.2%, 5.5%, 10.3% respectively). Twenty four participants (3.5%) reported handling bats or having bats in the house roof. Gender, age, and livelihood activities were shown to be significantly associated with participants' interactions with animals. Participants' knowledge of risks influenced their health-seeking behavior. CONCLUSION: The results suggest that there is a high level of interaction between humans, livestock, and wild animals in communities at sites we investigated in Thailand. This study highlights important differences among demographic and occupational risk factors as they relate to animal contact and zoonotic disease risk, which can be used by policymakers and local public health programs to build more effective surveillance strategies and behavior-focused interventions.