Lisa M. Casanova

Chitosan is a promising coagulant for bacteria, viruses and turbidity in water, but needs identification of optimal dose-polymer combinations. This research tested chitosans to identify dose range and characteristics that provide highest simultaneous reduction of bacteria, viruses, and turbidity, and possible coagulation mechanisms, including charge neutralization, sweep coagulation, and electrostatic patch. Three molecular weights (MW) and degrees of deacetylation (DD) were tested at doses 1, 3, 10 and 30 mg/L using jar tests in water containing clays, E. coli, and bacteriophage MS2. Turbidity removal was 93-99% at 1 and 3 mg/L, with no significant difference between MW. MW, DD and dose significantly affected viral and bacterial reduction. Across doses, MW 100,000 Da had highest mean log10 MS2 (3.5) and E. coli (3.5) reductions. The 100,000 Da/10 mg combination had the highest mean log10 E. coli (4.5) and MS2 (3.5) reductions simultaneously. Overall, 100,000 Da/3 mg and 1,000,000 Da/3 mg maximize reduction of turbidity and MS2, but not E. coli. 100,000 Da/10 mg maximized E. coli reduction and gave MS2 reductions similar to 100,000 Da/3 mg, but turbidity reduction was lower. Chitosan reduced turbidity, bacteria, and viruses in water, influenced by MW, DD, and dose. Data suggests that there is no single dose/MW/DD combination that produced significantly higher reductions of all three contaminants simultaneously but good removal of all three can be achieved with 100,000 Da at 3 or 10 mg/L. Chitosans can be effective coagulant-flocculants in water at reasonably achievable doses using polymer characteristics that are commercially available.

Background: During shortages, elastomeric half-mask respirators (EHMRs) are an alternative to reusing N95 filtering facepiece respirators but require between-use disinfection. The objectives of this study were to (a) measure microbial reductions on EHMR surfaces under laboratory conditions by a standardized procedure using wipes impregnated with health care disinfectants and to (b) measure microbial reductions on EHMRs disinfected by volunteer health care providers. Method: We inoculated EHMR (Honeywell model RU8500) surfaces with Pseudomonas aeruginosa, Bacillus atrophaeus spores, and bacteriophages MS2 and Φ6, and disinfected them using two wipes with hydrogen peroxide (HP), alcohols, and quaternary ammonium compounds (QACs). Then, we randomized 54 volunteer subjects into three groups (Group 1: two wipes with instructions, Group 2: five wipes with instructions, Group 3: no instructions or set number of wipes) and used 0.5% HP wipes without precleaning on EHMRs inoculated with Raoultella terrigena and MS2. Findings: The laboratory study demonstrated that all organisms achieved at least 4 log ₁₀ median reductions (HP>QAC/alcohol>QAC>QAC/saline). Pseudomonas was highly susceptible to HP and QAC/alcohol and Φ6 to all disinfectants. MS2 reduction was highest using HP and lowest using QAC/saline. Bacillus was least susceptible. The volunteer study showed a 3 to 4 log ₁₀ average reductions of bacteria and virus; Raoultella reductions were greater than MS2, with variability within and between subjects. Conclusions : HP disinfectant wipes used in laboratory and by volunteers reduce bacteria and viruses on EHMRs by 3 to 4 log ₁₀ on average. Implications for Practice: Commercially available hospital disinfectant wipes reduce bacteria and viruses on EHMRs and can fill the need for between-use disinfection. HP and combination QAC/alcohol have the greatest efficacy under our test conditions.

Escherichia coli are fecal indicator bacteria that reach waterbodies through aging and failing infrastructure in cities. Exposure to pathogens in untreated sewage can result in gastrointestinal disease, which frequently goes unreported. In the United States, the Clean Water Act regulates point source discharges of sewage and treated wastewater, but fecal indicator bacteria remain the second leading cause of river impairment. The burden of this contamination is not equitably distributed, with Black, Indigenous, and communities of color suffering from a disproportionate burden of untreated and overflowing waste and subsequent health impacts. Regulatory failures, and even abandonment, along with the exclusion of people of color from the mainstream environmental movement, mean that new approaches are needed to help communities empower themselves to address contamination. Community‐led groups that engage residents in addressing issues within and beyond regulatory frameworks have used approaches including trash traps, riparian planting and restoration, and community‐led monitoring. Mycofiltration, or the use of fungi to filter pollutants from water, is an emerging and understudied method of remediating E. coli. The low cost of mycofilter installation and maintenance may give agency to communities that have been unduly burdened with sewage contamination to diminish harmful exposures in the near term, even as they continue working toward longer‐term regulatory fixes. Continued research is needed to fully understand how different species of mycelium work under varying hydrologic conditions, including in‐field installations, along with long‐term monitoring and community acceptance to understand the efficacy and the potential impact of this strategy.

Surface waters used for drinking water supply often receive upstream wastewater effluent inputs, resulting in de facto wastewater reuse for drinking water and recreation. As populations grow, demands on water supplies increase. As this trend continues, it creates the need to understand the risks associated with such reuse. In North Carolina, potable reuse has been proposed as a combination of at least 80% surface water with up to 20% tertiary-treated, dual-disinfected, reclaimed wastewater, which is then stored for 5 days and further treated using conventional drinking water treatment methods. The state of North Carolina has set standards for both intake surface water and for the reclaimed water produced by wastewater utilities, using indicator microorganisms to measure compliance. The goal of this study was to quantify fecal indicator microorganisms, specifically E. coli, coliphages, and C. perfringens as well as key pathogens, specifically Salmonella spp. bacteria, adenoviruses, noroviruses, and the protozoan parasites Cryptosporidium and Giardia, in two types of water representing potential candidates for potable reuse in North Carolina, (1) run of river surface water and (2) sewage-impacted surface waters, with the purpose of determining if there are predictive relationships between these two microorganism groups that support microbial indicator reliability.

Hog production takes place mostly in large concentrated animal feeding operations (CAFOs) where waste is managed by storing in lagoons prior to land application of lagoon liquid. Salmonella, including antibiotic resistant Salmonella, have been found in the farm environment and lagoons. The objective of this research was to determine whether Salmonella resistant to clinically relevant antibiotics were present in wastewaters and surface waters from hog CAFOs. Samples of hog waste and on farm environmental waters were analysed for Salmonella, which were tested for antimicrobial susceptibility. The highest percentage of resistant isolates were found in raw waste flushed from hog houses and in lagoon wastewater; few resistant isolates were found in on‐farm surface water. Resistance to sulfamethoxazole was most common, mostly in waste samples and less commonly in surface water, followed by chloramphenicol and ampicillin. No resistance to cephalosporin or fluoroquinolones was found. Resistance to clinically relevant antibiotics was commonly found in Salmonella from hog waste but was less extensive in farm surface waters. Management of wastes from hog CAFOs should be designed to further reduce the risk of human exposures resulting from environmental contamination with Salmonella.

Turbidity reduction by coagulation-flocculation in drinking water reduces microbes and organic matter, increasing effectiveness of downstream treatment. Chitosan is a promising household water coagulant, but needs parameters for use. This study tested the effects of chitosan dose, molecular weight (MW), degree of deacetylation (DD), and functional groups on bentonite and kaolinite turbidity reduction in model household drinking water. Higher MW or DD produced greater reductions. Highest reductions were at doses 1 and 3 mg/L by MW >50,000 or >70% DD (residual turbidity <5 NTU). Higher doses did not necessarily continually increase reduction. For functional groups, 3 mg/L produced the highest reductions by lactate, acetate, and HCl, and lower reductions of kaolinite than bentonite. Doses where the point of zero charge was observed clustered around 3 mg/L. Chitosan reduced clay turbidity in water; effectiveness was influenced by dose, clay type, MW, DD, and functional groups. Reduction did not necessarily increase with MW. Bentonite had a broader effective dose range and higher reduction at the optimal dose than kaolinite. Chitosans with and without functional groups performed similarly. The best of the studied doses was 3 mg/L. Chitosans are promising for turbidity reduction in low-resource settings if combined with sedimentation and/or filtration. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Personal protective equipment (PPE) protects healthcare workers (HCWs) caring for patients with Ebola virus disease (EVD), and PPE doffing is a critical point for preventing viral self-contamination. We assessed contamination of skin, gloves, and scrubs after doffing Ebola-level PPE contaminated with surrogate viruses: bacteriophages MS2 and Φ6. In a medical biocontainment unit, HCWs (n = 10) experienced in EVD care donned and doffed PPE following unit protocols that incorporate trained observer guidance and alcohol-based hand rub (ABHR). A mixture of Φ6 (enveloped), MS2 (nonenveloped), and fluorescent marker was applied to 4 PPE sites, approximating body fluid viral load (Φ6, 10⁵; MS2, 10⁶). They performed a patient care task, then doffed. Inner gloves, face, hands, and scrubs were sampled for virus, as were environmental sites with visible fluorescent marker. Among 10 HCWs there was no Φ6 transfer to inner gloves, hands, or face; 1 participant had Φ6 on scrubs at low levels (1.4 × 10²). MS2 transfer (range, 10¹–10⁶) was observed to scrubs (n = 2), hands (n = 1), and inner gloves (n = 7), where it was highest. Most (n = 8) had only 1 positive site. Environmental samples with visible fluorescent marker (n = 21) were negative. Among experienced HCWs, structured, observed doffing using ABHR protected against hand contamination with enveloped virus. Nonenveloped virus was infrequent on hands and scrubs but common on inner gloves, suggesting that inner gloves, but not necessarily ABHR, protect against hand contamination. Optimizing doffing protocols to protect against all types of viruses may require reinforcing careful handling of scrubs and good glove/hand hygiene with effective agents.

Households that lack piped water supply are often forced to meet water needs by storing in the home, leaving water vulnerable to contamination by viruses. Storage in copper containers can potentially prevent this type of contamination, but the inactivation kinetics of viruses by copper need to be described to make appropriate storage recommendations. This work characterized inactivation kinetics of bacteriophage MS2 as a surrogate for enteric viruses by dissolved ionic copper in water. Reduction of MS2 increased with increasing doses of copper. At 0.3 mg/L, there was a 1.8-log₁₀ reduction of MS2 within 6 h. At 1 and 3 mg/L, 2–2.5 log₁₀ inactivation could be achieved between 6 and 24 h. Parameters for the Chick-Watson, Hom, and One Hit-Two Population models of inactivation were calculated and evaluated, all of which demonstrated strong goodness-of-fit and predictability at various contact times. Copper inactivates MS2 under controlled conditions at doses between 0.3 and 3 mg/L. Although requiring longer contact times than conventional disinfectants, it is a candidate for improving the safety of stored drinking water.