Exploring the role of wastewater-based epidemiology in understanding tuberculosis burdens in Africa

Wastewater surveillance for chronic disease drugs in wastewater treatment plants: Mass load, removal, and sewage epidemiology

As the number of chronic disease patients continues to climb, vast quantities of chronic disease drugs are continuously discharged into the wastewater treatment plants (WWTPs) and then are released to the receiving environment. However, the situations of pollution, removal, and consumption of chronic disease drugs in China were not studied. Here we investigated the mass load and removal efficiency of 14 chronic disease drugs in seven wastewater treatment plants (WWTPs) of Guangdong Province, China, and estimated the proportional usage of chronic disease drugs and the prevalence of chronic diseases by wastewater-based epidemiology (WBE) method. The results showed that all target chronic disease drugs were detected in the WWTPs, among which gliclazide, valsartan, and bezafibrate were the mainly detected antidiabetic drug, antihypertensive drug, and antihyperlipidemic drug, respectively. The aqueous removal rates of chronic disease drugs ranged from -163 %-100 % in studied WWTPs, and most chronic disease drugs were mainly removed at anaerobic stage in WWTPs that using Anaerobic-Anoxic-Oxic treatment technologies. Mean mass loads of chronic disease drugs in the influent of seven WWTPs ranged at 72-318099 mg·d-1 (valsartan), and mean emission of chronic disease drugs in seven WWTPs ranged at 0-56.3 mg·d-1·1000 inhabitant-1 (valsartan). Based on the WBE method, the prevalence of diabetes, hypertension, and dyslipidemia estimated by gliclazide, glipizide, valsartan, and bezafibrate in this study was consistent with those obtained via cross-sectional survey. The results formulated the contamination characteristics of chronic disease drugs in China and assessed the accuracy of chronic disease drugs used for disease prevalence estimation.

Genomic insights into chlorine resistance of a Mycobacterium sp. strain isolated from treated wastewater effluent

Chlorine is the principal microbial disinfectant used for water treatment. However, chlorine-resistant bacteria such as Mycobacterium spp., can survive chlorine treatment and even grow in the presence of chlorine, posing potential public health risks. In this study, we isolated a Mycobacterium sp. strain from treated effluent and investigated its chlorine resistance and recovery using transcriptomic analyses. Specifically, isolate M1, showing 94.58 % average nucleotide identity (ANI) with Mycobacterium massilipolynesiensis type genome, was exposed to 1 ppm HOCl for 30 min and subjected to RNA sequencing. Genes identified as upregulated compared to control conditions (no HOCl) were involved in detoxification (toxic compound degradation; nemA; log2 fold-change [FC]: 7.41), redox homeostasis (COQ5; quinone synthesis; log2 FC 5.70, rosB; riboflavin synthesis; log2 FC 5.61), protein homeostasis (cysHKO, moeZ cysteine biosynthesis, and arg complex; arginine metabolism), and lipid metabolism (cpnA; 6.95 FC) suggesting a multifaceted adaptation to oxidative stress. Levels of a few membrane transport proteins (czcD, and bcr) were also upregulated, highlighting their role in chlorine exposure. Overall, this study broadens the understanding of chlorine resistance strategies employed by Mycobacterium sp. to combat oxidative stress and the resulting toxic intracellular compounds, and has implications for adjusting water treatment technologies toward eliminating mycobacteria.

A Perspective on Wastewater and Environmental Surveillance as a Public Health Tool for Low- and Middle-Income Countries

Geographical variations in infectious diseases create differences in public health priorities between high- and low-income countries. Low- and middle-income countries (LMICs) face resource constraints that limit adherence to international monitoring standards for wastewater-based epidemiology (WBE). The development of low-cost WBE programs, such as those to detect SARS-CoV-2, offers LMICs a promising tool for monitoring pathogens of local concern. In this work, we summarize important wastewater biomarkers for LMICs and their associated public health challenges, ranging from pathogens causing gastroenteritis to putative markers for plant diseases linked to food safety, as well as antimicrobial resistance. We raise awareness of the great potential of WBE for LMICs and highlight the critical health markers, research needs, and strategies necessary to establish tailored wastewater surveillance programs.

Surveillance of public health pathogens in Lagos wastewater canals: a cross-sectional study

BACKGROUND

Wastewater-based epidemiology (WBE) is already being adopted for the surveillance of health conditions of communities and shows great potential for the monitoring of infectious pathogens of public health importance. There is however paucity of robust data to support extensive WBE in Nigeria. This study evaluated the prevalence of clinically relevant infectious pathogens and provided antimicrobial resistance profiles of bacteria pathogens in wastewater canals in Lagos State at a single point in time.

METHODS

This is a cross-sectional survey of wastewater canals in 20 Local Government Areas (LGAs) in Lagos State for detection of bacteria pathogens of public health importance including non-tuberculous mycobacteria and SARS-Cov-2 virus using cultural analysis and conventional Polymerase Chain Reaction (PCR) techniques. Descriptive epidemiological survey of communities around the canals was done using questionnaires to assess exposure pathways. Statistical analysis was done using SPSS version 27 while P value of < 0.05 was considered as significant.

RESULTS

Three thousand and fifty-four (3054) questionnaires were administered to 1215 (39.8%) females and 1658 (54.3%) males in communities situated around 40 canals in 20 LGAs. Although majority (81.8%) reported using water closet toilet system and pit latrine (12.5%), a few of them admitted to open defaecation [101 (3.3%)] while 299 (9.8%) engaged in open field waste disposal. SARS-CoV-2 was not detected from wastewater in this study. Two mycobacterial species that included Mycobacterium fortitium group (13, 32.5%) and Mycobacterium kansasii (11, 27.5%) were identified in 15 out of 20 LGAs sampled. A total of 123 bacteria pathogens were isolated across the 40 canals. Prominent enteropathogens isolated included Escheriachia coli (28.5%), Salmonella spp (16.3%), Vibro cholerae (10.6%) and Shigella spp (5.7%). Extended spectrum beta-lactamase genes were prominent (87.5%) in the wastewater samples with almost a half (42.5%) of the canals containing both SHV and CTX-M.

CONCLUSION

This study highlights the presence of pathogens with potential to cause epidemic in wastewater canals in Lagos State and provides evidence to inform policy and strategies for wastewater monitoring and treatment. Further studies involving longitudinal monitoring of time-based variations is needed to identify trends in pathogen loads and AMR patterns over time.

Identification and molecular characterization of Mycobacterium bovis DNA in GeneXpert® MTB/RIF ultra-positive, culture-negative sputum from a rural community in South Africa

This study investigated the presence of Mycobacterium bovis (M. bovis) DNA in archived human sputum samples previously collected from residents who reside adjacent to the M. bovis-endemic Hluhluwe-iMfolozi wildlife park, South Africa (SA). Sixty-eight sputum samples were GeneXpert MTB/RIF Ultra-positive for M. tuberculosis complex (MTBC) DNA but culture negative for M. tuberculosis. Amplification and Sanger sequencing of hsp65 and rpoB genes from DNA extracted from stored heat-inactivated sputum samples confirmed the presence of detectable amounts of MTBC from 20 out of the 68 sputum samples. Region of difference PCR, spoligotyping and gyrB long-read amplicon deep sequencing identified M. bovis (n = 10) and M. tuberculosis (n = 7). Notably, M. bovis spoligotypes SB0130 and SB1474 were identified in 4 samples, with SB0130 previously identified in local cattle and wildlife and SB1474 exclusively in African buffaloes in the adjacent park. M. bovis DNA in sputum, from people living near the park, underscores zoonotic transmission potential in SA. Identification of spoligotypes specifically associated with wildlife only and spoligotypes found in livestock as well as wildlife, highlights the complexity of TB epidemiology at wildlife-livestock-human interfaces. These findings support the need for integrated surveillance and control strategies to curb potential spillover and for the consideration of human M. bovis infection in SA patients with positive Ultra results.

Optimisation of analytical methods for tuberculosis drug detection in wastewater: A multinational study

Wastewater-based epidemiology (WBE) is a robust tool for disease surveillance and monitoring of pharmaceutical consumption. However, monitoring tuberculosis (TB) drug consumption faces challenges due to limited data availability. This study aimed to optimise methods for detecting TB drugs in treated and untreated wastewater from four African countries: South Africa, Nigeria, Kenya, and Cameroon. The limit of detection (LOD) for these drugs ranged from a minimum of 2.20 (±1.02) for rifampicin to a maximum of 2.95 (±0.79) for pyrazinamide. A parallel trend was observed concerning the limit of quantification (LOQ), with rifampicin reporting the lowest average LOQ of 7.33 (±3.44) and pyrazinamide showing the highest average LOQ of 9.81 (±2.64). The variance in LOD and LOQ values could be attributed to factors such as drug polarity. Erythromycin and rifampicin exhibited moderately polar LogP values (2.6 and 2.95), indicating higher lipid affinity and lower water affinity. Conversely, ethambutol, pyrazinamide, and isoniazid displayed polar LogP values (-0.059, -0.6, and -0.7), suggesting lower lipid affinity and greater water affinity. The study revealed that storing wastewater samples for up to 5 days did not result in significant drug concentration loss, with concentration reduction remaining below 1 log throughout the storage period. Application of the optimised method for drug detection and quantification in both treated and untreated wastewater unveiled varied results. Detection frequencies varied among drugs, with ethambutol consistently most detected, while pyrazinamide and isoniazid were least detected in wastewater from only two countries. Most untreated wastewater samples had undetectable drug concentrations, ranging from 1.21 ng/mL for erythromycin to 54.61 ng/mL for isoniazid. This variability may suggest differences in drug consumption within connected communities. In treated wastewater samples, detectable drug concentrations ranged from 1.27 ng/mL for isoniazid to 10.20 ng/mL for ethambutol. Wastewater treatment plants exhibited variable removal efficiencies for different drugs, emphasising the need for further optimisation. Detecting these drugs in treated wastewater suggests potential surface water contamination and subsequent risks of human exposure, underscoring continued research's importance.