As a postdoctoral scholar interested in the intersections of human health, animal health, and the environment, I work across disciplines in Environmental Engineering (with Alexandria Boehm) and Epidemiology (with Jade Benjamin-Chung). My current work focuses on understanding the mechanisms of pathogen survival (including parasites and viruses) in the environment and microbial source tracking. My dissertation work centered on enveloped viruses, with a particular focus on understanding their persistence in the environment, transmission dynamics, and intervention strategies, especially in resource-constrained environments. Beyond my academic pursuits, I'm dedicated to increasing diversity, equity, and inclusion through outreach programs for students in every level of their education.

Stanford Advisors

All Publications

  • Strengthening the academic pipeline for underrepresented students via early exposure to graduate education Chem Fernandez, S., Anderson, C. E., Boehm, A. B., Congreve, D. N. 2024; 10 (6): 1609-1619
  • Sunlight Inactivation of Enveloped Viruses in Clear Water. Environmental science & technology Anderson, C. E., Boehm, A. B. 2023


    Enveloped virus fate in the environment is not well understood; there are no quantitative data on sunlight inactivation of enveloped viruses in water. Herein, we measured the sunlight inactivation of two enveloped viruses (Phi6 and murine hepatitis virus, MHV) and a nonenveloped virus (MS2) over time in clear water with simulated sunlight exposure. We attenuated UV sunlight wavelengths using long-pass 50% cutoff filters at 280, 305, and 320 nm. With the lowest UV attenuation tested, all decay rate constants (corrected for UV light screening, k̂) were significantly different from dark controls; the MS2 k̂ was equal to 4.5 m2/MJ, compared to 16 m2/MJ for Phi6 and 52 m2/MJ for MHV. With the highest UV attenuation tested, only k̂ for MHV (6.1 m2/MJ) was different from the dark control. Results indicate that the two enveloped viruses decay faster than the nonenveloped virus studied, and k̂ are significantly impacted by UV attenuation. Differences in k̂ may be due to the presence of viral envelopes but may also be related to other differing intrinsic properties of the viruses, including genome length and composition. Reported k̂ values can inform strategies to reduce the risk from exposure to enveloped viruses in the environment.

    View details for DOI 10.1021/acs.est.3c06680

    View details for PubMedID 38062652

  • Enveloped and non-enveloped virus survival on microfiber towels. PeerJ Anderson, C. E., Wolfe, M. K., Boehm, A. B. 2023; 11: e15202


    Handwashing is an important intervention which can reduce indirect disease transmission, however soap and water for handwashing purposes is not available in some low-resource regions. When handwashing with soap and water is not possible, individuals may use alternatives such as the Supertowel (a microfiber towel with an antimicrobial coating). Testing of viral inactivation as a result of antimicrobial treatment on the Supertowel, however, has been limited. The goal of this study is to provide information about the performance of the Supertowel's antimicrobial treatment against viruses, which will help inform the use of the towels as handwashing alternatives.We seeded the Supertowel and a regular microfiber towel with two bacteriophages (enveloped Phi6 and non-enveloped MS2) and monitored viral inactivation over time. Additionally, we assessed if temperature, humidity, whether the towel was initially wet or dry, or virus type had an effect on viral decay rate constants. Virus concentrations were measured repeatedly over 24 h.We found that neither towel type (whether the towel was a Supertowel or a regular microfiber towel) nor humidity were significant variables in our model of decay rate constants (P = 0.06 and P = 0.22, respectively). We found that the variables of temperature, whether towels were initially wet versus dry, and virus type were significantly different from 0, suggesting that these variables explained variance in the decay rate constant (P = 6.55 × 10-13, P = 0.001, and P < 2 × 10-16, respectively). Higher temperatures, dry towels, and enveloped viruses all resulted in increases in the decay rate constant.Viruses seeded onto a Supertowel decay similar to viruses seeded onto a regular towel indicating that the virucidal potential of the Supertowel is minimal.

    View details for DOI 10.7717/peerj.15202

    View details for PubMedID 37073274

    View details for PubMedCentralID PMC10106082

  • Investigating the Efficacy of Various Handwashing Methods against Enveloped and Non-Enveloped Viruses. The American journal of tropical medicine and hygiene E Anderson, C., Tong, J., Zambrana, W., B Boehm, A., K Wolfe, M. 2023


    Respiratory and diarrheal diseases are leading causes of death worldwide. Handwashing may reduce disease; however, recommended methods (soap and water for 20 seconds) are not always possible, particularly in low-resource settings. The aim of this study is to evaluate handwashing when recommended methods are not feasible, including washing with water only, washing with soapy water, washing for a short duration, using alcohol-based hand sanitizer (ABHS), and cleaning hands with towels. To evaluate laboratory efficacy, we seeded MS2 (a non-enveloped virus) and Phi6 (an enveloped virus) onto the hands of volunteers who then washed their hands. Viruses remaining were recovered and quantified using culture-based and molecular methods to determine the log reduction value (LRV) after washing. Results indicated that washing with water only and with soapy water were similar to washing with soap and water for 20 seconds for both viruses (median LRV for MS2 = 2.8; Phi6 = 3.2). Most towel alternative conditions had LRVs significantly smaller than LRVs from washing with soap and water for either virus. LRVs of ABHS and soap and water for 5 seconds were similar to soap and water for 20 seconds for Phi6 but less for MS2 (median MS2 LRV differences = 2.5 and 0.51 for ABHS and soap and water for 5 seconds, respectively). Additionally, LRVs determined using molecular methods were in agreement with those obtained using culture-based methods. These results suggest some handwashing alternatives were as effective as recommended methods whereas others were not, and inform recommendations and future research on handwashing alternatives in low-resource settings.

    View details for DOI 10.4269/ajtmh.22-0287

    View details for PubMedID 36780893

  • Controlling contaminants using a far-UVC-based advanced oxidation process for potable reuse Nature Water Yin, R., Anderson, C., Zhao, J., Boehm, A., Mitch, W. 2023: 555–562
  • Quantifying the Viral Reduction Achieved Using Ash and Sand as Handwashing Agents. The American journal of tropical medicine and hygiene Zambrana, W., Tong, J., E Anderson, C., B Boehm, A., Wolfe, M. K. 2022


    The WHO recommends handwashing with soap and water for 20-40 seconds. In settings where soap is not available, ash or sand is used for handwashing, yet their efficacy as handwashing materials is underresearched. The purpose of this study was to quantify the removal of viruses using ash and sand as handwashing agents, and compare their efficacy to commonly recommended handwashing methods. We performed a volunteer study to estimate the log reduction value (LRV) of model viruses Phi6 and MS2 on hands after six handwashing conditions: two handwashing agents (ash and water, and sand and water) with two time points (5 and 20 seconds), and two handwashing agents (soap and water, and water only) with one time point (20 seconds). Plaque assays were used to measure infectious virus reduction. Handwashing with any of the handwashing agents for 20 seconds resulted in a greater LRV than the 2-log reduction U.S. Food and Drug Administration criteria for both viruses. Soap and water resulted in a significantly greater LRV (2.7-4.8) than washing with ash and water (2.0-2.8) or sand and water (1.8-2.7) for 5 seconds for both viruses, and water only resulted in a significantly higher LRV (2.8) than all ash (2.0-2.6) and sand (1.8-2.4) conditions for MS2 only. These results suggest that using ash or sand as handwashing agents can be efficacious in reducing viruses but may be less efficacious than soap, especially when used for shorter durations. Further research should investigate the use of ash and sand as handwashing agents in real-world settings.

    View details for DOI 10.4269/ajtmh.22-0581

    View details for PubMedID 36535259

  • Viral pathogens in urban stormwater runoff: Occurrence and removal via vegetated biochar-amended biofilters. Water research Graham, K. E., Anderson, C. E., Boehm, A. B. 2021; 207: 117829


    Urban runoff is one of the greatest sources of microbial pollution to surface waters. Biofilters can limit the impact of stormwater runoff on surface water quality by diverting runoff from receiving waters. However, our understanding of how biofilter design choices, including the addition of vegetation and geomedia, may impact the removal of pathogens is lacking. In this study, we characterized viruses (adenovirus, enterovirus, norovirus GII, crAssphage) in San Francisco Bay area urban runoff and assessed the removal of lab-cultured viruses (MS2, adenovirus 2, coxsackievirus B5) from biochar-amended biofilter mesocosms during challenge testing. We quantified viruses using (RT-)qPCR and F+ coliphage plaque assays. We found that all the pathogenic viruses targeted were found at low concentrations (adenovirus: all positive samples were

    View details for DOI 10.1016/j.watres.2021.117829

    View details for PubMedID 34763278

  • Transfer rate of enveloped and non-enveloped viruses between fingerpads and surfaces. Applied and environmental microbiology Anderson, C. E., Boehm, A. B. 2021: AEM0121521


    Fomites can represent a reservoir for pathogens, which may be subsequently transferred from surfaces to skin. In this study we aim to understand how different factors (including virus type, surface type, time since last handwash, and direction of transfer) affect virus transfer rates, defined as the fraction of virus transferred, between fingerpads and fomites. To determine this, 360 transfer events were performed with 20 volunteers using Phi6 (a surrogate for enveloped viruses) and MS2 (a surrogate for non-enveloped viruses), and three clean surfaces (stainless steel, painted wood, and plastic). Considering all transfer events (all surfaces and both transfer directions combined), the mean transfer rates of Phi6 and MS2 were 0.17 and 0.26, respectively. Transfer of MS2 was significantly higher than Phi6 (P<0.05). Surface type was a significant factor that affected the transfer rate of Phi6: Phi6 is more easily transferred to and from stainless steel and plastic than to and from painted wood. Direction of transfer was a significant factor affecting MS2 transfer rates: MS2 is more easily transferred from surfaces to fingerpads than from fingerpads to surfaces. Data from these virus transfer events, and subsequent transfer rate distributions, provide information which can be used to refine quantitative microbial risk assessments. This study provides a large-scale data set of transfer events with a surrogate for enveloped viruses, which extends the reach of the study to the role of fomites in the transmission of human enveloped viruses like influenza and SARS-CoV-2. Importance This study created a large-scale data set for the transfer of enveloped viruses between skin and surfaces. The data set produced by this study provides information on modelling the distribution of enveloped and non-enveloped virus transfer rates, which can aid in the implementation of risk assessment models in the future. Additionally, enveloped and non-enveloped viruses were applied to experimental surfaces in an equivalent matrix to avoid matrix effects, so results between different viral species can be directly compared without confounding effects of different matrices. Our results indicating how virus type, surface type, time since last handwash, and direction of transfer affect virus transfer rates can be used in decision-making processes to lower the risk of viral infection from transmission through fomites.

    View details for DOI 10.1128/AEM.01215-21

    View details for PubMedID 34469200

  • Effects of an urban sanitation intervention on childhood enteric infection and diarrhea in Maputo, Mozambique: A controlled before-and-after trial. eLife Knee, J., Sumner, T., Adriano, Z., Anderson, C., Bush, F., Capone, D., Casmo, V., Holcomb, D., Kolsky, P., MacDougall, A., Molotkova, E., Braga, J. M., Russo, C., Schmidt, W. P., Stewart, J., Zambrana, W., Zuin, V., Nalá, R., Cumming, O., Brown, J. 2021; 10


    We conducted a controlled before-and-after trial to evaluate the impact of an onsite urban sanitation intervention on the prevalence of enteric infection, soil transmitted helminth re-infection, and diarrhea among children in Maputo, Mozambique. A non-governmental organization replaced existing poor-quality latrines with pour-flush toilets with septic tanks serving household clusters. We enrolled children aged 1-48 months at baseline and measured outcomes before and 12 and 24 months after the intervention, with concurrent measurement among children in a comparable control arm. Despite nearly exclusive use, we found no evidence that intervention affected the prevalence of any measured outcome after 12 or 24 months of exposure. Among children born into study sites after intervention, we observed a reduced prevalence of Trichuris and Shigella infection relative to the same age group at baseline (<2 years old). Protection from birth may be important to reduce exposure to and infection with enteric pathogens in this setting.

    View details for DOI 10.7554/eLife.62278

    View details for PubMedID 33835026

    View details for PubMedCentralID PMC8121544