HUMAN INFECTIOUS DISEASE​

Waterborne pathogens (viruses, bacteria, protozoa, helminths)

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CONSERVATION PROBLEM

Freshwater and/or nearshore marine habitat degradation via sedimentation, nutrient and chemical pollution, development, etc.

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INTERVENTION

Conserve/restore seagrass beds or wetlands or construct man-made wetlands. (See this related water treatment case study for more evidence.) 

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TARGET

Environmental pathogens in water used by humans for drinking, recreation, or other life activities (e.g., consuming contaminated shellfish).

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MECHANISM

Plants, plant-associated microbes, and slow-moving water inactivate environmental enteric pathogens via negative biotic interactions and/or exposure to UV light. Therefore, conserving/restoring/creating wetlands might decrease pathogens in water contacted by humans.

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HUMAN INFECTIOUS DISEASE EVIDENCE

OBSERVATIONAL: Near Indonesian islands without waste management, there were higher loads of bacterial pathogens that infect humans, fish, and invertebrates in areas where seagrass beds were absent compared to areas with seagrass beds. EXPERIMENTS AND META-ANALYSES: Constructed wetlands can reduce enteric pathogens (e.g.., there are higher pathogen densities in runoff water entering wetlands than in water leaving wetlands and heading downstream towards other water bodies). However, wetland effluent often still has pathogen concentrations above standards for re-use, and efficiency varies with wetland type/design. SYSTEMATIC REVIEW: People do become infected with enteric pathogens through interactions with source water, but contamination after collecting (i.e., within household storage containers) is likely a larger source of infections that will persist despite wetland restoration. 

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CONSERVATION EVIDENCE

OBSERVATIONAL: Constructed and restored wetlands can have water quality and biodiversity that are as high as that in unperturbed natural wetlands. BEFORE-AFTERS: Constructing/restoring wetlands can increase water quality and biodiversity, but results vary with wetland design and projects vary in their conservation goals. 

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LOCATION AND SPATIAL SCALE

Waterborne pathogens, wetland degradation, and nearshore marine habitat degradation are global issues. Enteric pathogens are especially important in areas without water treatment systems. Actions will likely be most effective at the local to watershed scales.

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TEMPORAL SCALE

It typically takes years to build and/or restore wetlands.

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HEALTH SUCCESS METRICS

Fewer environmental pathogens or fecal indicators in water bodies. Hypothetically, reduced human infections, but no studies have quantified human infection.

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CONSERVATION SUCCESS METRICS

Improved water quality indices, reduced disease in fish/corals nearby seagrass beds, increased biodiversity

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HUMAN CO-BENEFITS

Contamination by pollutants other than enteric pathogens might be reduced. Wetlands can also provide aesthetic values and flood control.

 

CONSERVATION CO-BENEFITS

Reduced downstream eutrophication/pollution

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COLLATERAL HUMAN IMPACTS

Restored or constructed wetlands might increase vectorborne infectious diseases (e.g., filariasis, onchocerciasis, leishmaniasis, malaria), but these effects might be mediated by vector control interventions and/or better wetland design.

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COLLATERAL CONSERVATION IMPACTS

Invasive plants could colonize constructed wetlands.

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SOCIAL ACCEPTABILITY

There might be conflicts with protecting particular freshwater or marine habitats, depending on how human activities need to be altered (e.g., development restrictions), but wetland restoration/construction is generally well-supported otherwise. 

 

EQUITY CONSIDERATIONS

People living close to wetlands/seagrass beds might experience most of the negative impacts (e.g., higher vector densities, development restrictions).  

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PRACTICALITY/CHALLENGES

It can take a long time to build/restore wetlands, and even longer for water quality to change as a result, so monitoring and sustaining success is difficult. COST-BENEFIT: Constructed wetlands cost less to create and maintain than water treatment facilities, but their effectiveness varies by wetland type.

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STATUS

Constructed wetlands are used to treat runoff from homes/businesses and cities in developed nations. RISE is one ongoing constructed wetlands project.

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RESEARCH NEEDS

Need intervention studies that link wetland filtration to human infection risk at and downstream from wetlands. 

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REFERENCES

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META-ANALYSES and SYSTEMATIC LITERATURE REVIEWS

J. Wright, S. Gundry, R. Conroy, Household drinking water in developing countries: a systematic review of microbiological contamination between source and point-of-use. Trop. Med. Int. Health. 9, 106–117 (2004).

 

S. Wu, P. N. Carvalho, J. A. Müller, V. R. Manoj, R. Dong, Sanitation in constructed wetlands: A review on the removal of human pathogens and fecal indicators. Science of The Total Environment. 541, 8–22 (2016).

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BEFORE-AFTER STUDIES

G. De Martis, B. Mulas, V. Malavasi, M. Marignani, Can Artificial Ecosystems Enhance Local Biodiversity? The Case of a Constructed Wetland in a Mediterranean Urban Context. Environ Manage. 57, 1088–1097 (2016).

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EXPERIMENTAL STUDIES

K. R. Hench, G. K. Bissonnette, A. J. Sexstone, J. G. Coleman, K. Garbutt, J. G. Skousen, Fate of physical, chemical, and microbial contaminants in domestic wastewater following treatment by small constructed wetlands. Water Research. 37, 921–927 (2003).

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OBSERVATIONAL STUDIES

G. Becerra-Jurado, G. Foster, R. Harrington, M. Kelly-Quinn, Integrated constructed wetlands: hotspots for freshwater coleopteran diversity in the landscape of Ireland. Biology and Environment: Proceedings of the Royal Irish Academy. 114B, 271–279 (2014).

 

L. E. Bortolotti, R. D. Vinebrooke, V. L. S. Louis, Prairie wetland communities recover at different rates following hydrological restoration. Freshwater Biology. 61, 1874–1890 (2016).

 

J. A. Falabi, C. P. Gerba, M. M. Karpiscak, Giardia and Cryptosporidium removal from waste-water by a duckweed (Lemna gibba L.) covered pond. Lett. Appl. Microbiol. 34, 384–387 (2002).

 

T. K. Graczyk, F. E. Lucy, L. Tamang, Y. Mashinski, M. A. Broaders, M. Connolly, H.-W. A. Cheng, Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment. Appl. Environ. Microbiol. 75, 4531–4538 (2009).

 

J. B. Lamb, J. A. J. M. van de Water, D. G. Bourne, C. Altier, M. Y. Hein, E. A. Fiorenza, N. Abu, J. Jompa, C. D. Harvell, Seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates. Science. 355, 731–733 (2017).

 

M. J. Quiñónez-Díaz, M. M. Karpiscak, E. D. Ellman, C. P. Gerba, Removal of pathogenic and indicator microorganisms by a constructed wetland receiving untreated domestic wastewater. J Environ Sci Health A Tox Hazard Subst Environ Eng. 36, 1311–1320 (2001).

 

M. A. Rodrigo, A. Valentín, J. Claros, L. Moreno, M. Segura, M. Lassalle, P. Vera, Assessing the effect of emergent vegetation in a surface-flow constructed wetland on eutrophication reversion and biodiversity enhancement. Ecological Engineering. 113, 74–87 (2018).

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REVIEWS

J. Vymazal, Removal of enteric bacteria in constructed treatment wetlands with emergent macrophytes: a review. J Environ Sci Health A Tox Hazard Subst Environ Eng. 40, 1355–1367 (2005).

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OTHER SUPPORTING INFORMATION

S. B. Claflin, C. E. Webb, Surrounding land use significantly influences adult mosquito abundance and species richness in urban mangroves. Wetlands Ecol Manage. 25, 331–344 (2017).

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M. E. DeLorenzo, B. Thompson, E. Cooper, J. Moore, M. H. Fulton, A long-term monitoring study of chlorophyll, microbial contaminants, and pesticides in a coastal residential stormwater pond and its adjacent tidal creek. Environ Monit Assess. 184, 343–359 (2012).

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O. Donde, B. Xiao, Understanding wastewater treatment mechanisms: A review on detection, removal and purification efficiencies of faecal bacteria indicators across constructed wetlands. Environmental Reviews. 25 (2017), doi:10.1139/er-2017-0017.

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J. N. Hogan, M. E. Daniels, F. G. Watson, S. C. Oates, M. A. Miller, P. A. Conrad, K. Shapiro, D. Hardin, C. Dominik, A. Melli, D. A. Jessup, W. A. Miller, Hydrologic and Vegetative Removal of Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii Surrogate Microspheres in Coastal Wetlands. Appl Environ Microbiol. 79, 1859–1865 (2013).

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S. C. Jiang, K.-Y. Lim, X. Huang, D. McCarthy, A. J. Hamilton, Human and environmental health risks and benefits associated with use of urban stormwater. WIREs Water. 2, 683–699 (2015).

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P. T. J. Johnson, S. H. Paull, The ecology and emergence of diseases in fresh waters. Freshwater Biology. 56, 638–657 (2011).

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S. Kawecki, G. Kuleck, J. H. Dorsey, C. Leary, M. Lum, The prevalence of antibiotic-resistant bacteria (ARB) in waters of the Lower Ballona Creek Watershed, Los Angeles County, California. Environ Monit Assess. 189, 261 (2017).

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R. J. Lara, M. S. Islam, S. Yamasaki, S. B. Neogi, G. B. Nair, Aquatic Ecosystems, Human Health, and Ecohydrology. Treatise on Estuarine and Coastal Science, 263–299 (2011).

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H. L. Malan, C. C. Appleton, J. A. Day, J. Dini, Review: Wetlands and invertebrate disease hosts: Are we asking for trouble? Water SA. 35 (2009), doi:10.4314/wsa.v35i5.49202.

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J. Maschinski, G. Southam, J. Hines, S. Strohmeyer, Efficiency of a Subsurface Constructed Wetland System Using Native Southwestern U.S. Plants. Journal of Environmental Quality. 28, 225–231 (1999).

 

J. M. Medlock, A. G. C. Vaux, Impacts of the creation, expansion and management of English wetlands on mosquito presence and abundance - developing strategies for future disease mitigation. Parasit Vectors. 8, 142 (2015).

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V. Mezzanotte, F. Marazzi, M. Bissa, S. Pacchioni, A. Binelli, M. Parolini, S. Magni, F. M. Ruggeri, C. De Giuli Morghen, C. Zanotto, A. Radaelli, Removal of enteric viruses and Escherichia coli from municipal treated effluent by zebra mussels. Sci Total Environ. 539, 395–400 (2016).

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C. G. Murray, A. J. Hamilton, REVIEW: Perspectives on wastewater treatment wetlands and waterbird conservation. Journal of Applied Ecology. 47, 976–985 (2010).

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B. Okamura, S. W. Feist, Emerging diseases in freshwater systems. Freshwater Biology. 56, 627–637 (2011).

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M. L. Partyka, R. F. Bond, J. A. Chase, L. Kiger, E. R. Atwill, Multistate Evaluation of Microbial Water and Sediment Quality from Agricultural Recovery Basins. J Environ Qual. 45, 657–665 (2016).

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C. L. Rea, M. S. Bisesi, W. Mitsch, R. Andridge, J. Lee, Human health-related ecosystem services of avian-dense coastal wetlands adjacent to a Western Lake Erie swimming beach. Ecohealth. 12, 77–87 (2015).

 

R. C. Russell, Constructed wetlands and mosquitoes: Health hazards and management options—An Australian perspective. Ecological Engineering. 12, 107–124 (1999).

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S. L. Wear, Battling a Common Enemy: Joining Forces in the Fight against Sewage Pollution. BioScience. 69, 360–367 (2019).

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G. Wilkes, N. J. Ruecker, N. F. Neumann, V. P. J. Gannon, C. Jokinen, M. Sunohara, E. Topp, K. D. M. Pintar, T. A. Edge, D. R. Lapen, Spatiotemporal Analysis of Cryptosporidium Species/Genotypes and Relationships with Other Zoonotic Pathogens in Surface Water from Mixed-Use Watersheds. Appl. Environ. Microbiol. 79, 434–448 (2013).

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Page last updated: 3/14/2021 

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