Comparative analysis of membrane filter diameters for detection of selected viruses in wastewater samples.

Wastewater serves as a valuable source of information as it contains biological markers that have been shed by infected individuals and from other biological organisms such as plants and animals. Wastewater has been proven to indicate the presence of emerging pathogens in a community before the manifestation of clinical symptoms. Several methods of concentration and nucleic acid extraction have been employed all around the world without a unified method. One such method involves the use of the adsorption extraction method (AE-method), which involves the use of electronegative membrane filters of different pore sizes. The membrane filters also differ by diameter, but no study has been reported on the effect of diameter on capture efficiency. This study was aimed at evaluating the comparative capture efficiency of two different membrane filter diameters of 45 and 90 mm with pore sizes of 0.45 µm for the detection of indicator and pathogenic viruses. Primary influent samples were obtained from two wastewater treatment plants in Baltimore, Maryland, between April 27 and June 29, 2023. A total of twenty samples were processed using 45- and 90-mm membrane filters. Nucleic acids were extracted from the filters using the QIAmp Viral RNA Mini Kit and assayed for four different targets: PMMoV, Norovirus (GI and GII), and CrAssphage by RT-qPCR. The result showed that 45 mm membrane filters had a higher combined mean capture efficiency in log10 gene copies per liter (gc/l) for crAssphage (7.40) than 90 mm membrane filters (7.10). Similarly, the 45-mm filter had higher mean capture efficiency for Norovirus GI (4.67) than the 90-mm filter (1.84) and likewise for Norovirus GII (2.14, 1.04). On the contrary, 90-mm membrane filters were observed to have better capture of PMMoV (6.84) compared to 45-mm membrane filters (6.69). This result therefore implies that 45-mm membrane filters could be more efficient for wastewater surveillance studies through the AE method for indicator viruses like CrAssphage and human disease-causing viruses like Norovirus.

Wastewater surveillance of Mpox virus in Baltimore.

This study aimed to utilize wastewater surveillance for monitoring Mpox cases at a community level. Untreated wastewater samples were collected once a week from two wastewater treatment plants (A and B) in Baltimore City from July 27, 2022-September 22, 2022. The samples were concentrated via an adsorption-elution (AE) method and Polyethylene Glycol (PEG) precipitation method followed by quantitative polymerase chain reaction (qPCR). Monkeypox virus (MPXV) was detected in 89 % (8/9) samples from WWTP A and 55 % (5/9) samples from WWTP B with at least one concentration method. Higher detection rate in samples concentrated with PEG precipitation compared to AE method was observed, indicating that PEG precipitation is a more effective virus concentration method for MPXV. To our knowledge, this is the first study reporting the detection of MPXV in wastewater in Baltimore. The results highlight that wastewater surveillance could be used as a complementary early warning tool for monitoring future Mpox outbreaks.