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.

Emergence of Vibrio parahaemolyticus serotype O10:K4 in Thailand.

An emerging serotype O10:K4 of Vibrio parahaemolyticus has been predominantly isolated from outbreaks and sporadic cases in China. Herein, we report the first case of infection due to V. parahaemolyticus O10:K4 isolated from a hospitalized patient with acute diarrhea in Thailand. We sequenced the whole genome of the O10:K4 strain and compared it with those of the pandemic O3:K6 strain, O10:K4 strains in China, and other clinical and environmental strains. The results suggested that the O10:K4 strains are not a mere serotype variant diverged from the pandemic O3:K6 strain, confirming that the O10:K4 strain emergence has spread to Southeast Asia.