title: Does the use of tubular digesters to treat livestock waste lower the risk of infection from Cryptosporidium parvum and Giardia lamblia?
abstract: Worldwide, high incidences of cryptosporidiosis and giardiasis are attributed to livestock waste. Quantitative microbial risk assessment can be used to estimate the risk of livestock related infections from Cryptosporidium parvum and Giardia lamblia. The objective of this paper was to assess the occupational and public health risks associated with management of raw and anaerobically digested livestock waste in two rural communities in Costa Rica based on fomite, soil and crop contamination and livestock waste management exposure pathways. Risks related to cattle waste were greater than swine waste due to cattle shedding more (oo)cysts. Cryptosporidium parvum also posed a greater risk than Giardia lamblia in all exposure pathways due to livestock shedding high loads of Cryptosporidium parvum oocysts and oocysts' lower inactivation rates during anaerobic digestion compared with Giardia lamblia cysts. The risk of infection from exposure to contaminated soil and crops was significantly lower for a community using tubular anaerobic digesters to treat livestock waste compared to a community where the untreated waste was applied to soil. The results indicate that treatment of livestock waste in small-scale tubular anaerobic digesters has the potential to significantly decrease the risk of infection below the World Health Organization's acceptable individual annual risk of infection (10-4).
authors.affiliation: Department of Civil and Environmental Engineering, University of South Florida, 4202 E Fowler Ave ENB 118, Tampa, FL 33620, USA E-mail: mk3855@columbia.edu; Present address: Department of Earth and Environmental Engineering, Columbia University, 500 W. 120th St. 918 S. W. Mudd Hall, 500, Manhattan, NY 10027, USA.
authors.forename: Maureen N
authors.initials: MN
authors.lastname: Kinyua
authors.affiliation: Department of Civil and Environmental Engineering, University of California, 760 Davis Hall Berkeley, Berkeley, CA 94720, USA.
authors.forename: Ileana
authors.initials: I
authors.lastname: Wald
authors.affiliation: University of Georgia, Costa Rica, Apartado 108-5655 Santa Elena de Monteverde, Puntarenas, Costa Rica.
authors.forename: Fabricio
authors.initials: F
authors.lastname: Camacho-Céspedes
authors.affiliation: Department of Global Health, University of South Florida, 4202 E Fowler Ave CPH 1127, Tampa, FL 33620, USA.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Izurieta
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, Drexel University, 251 Curtis Hall, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Haas
authors.affiliation: Department of Civil and Environmental Engineering, University of South Florida, 4202 E Fowler Ave ENB 118, Tampa, FL 33620, USA E-mail: mk3855@columbia.edu.
authors.forename: Sarina J
authors.initials: SJ
authors.lastname: Ergas
mesh_terms: D000818:Animals; D002417:Cattle; D003364:Costa Rica / Q000453:epidemiology; D003457:Cryptosporidiosis / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D016785:Cryptosporidium parvum / Q000302:isolation & purification; D004787:Environmental Pollution / Q000032:analysis*; D016829:Giardia lamblia / Q000302:isolation & purification; D005873:Giardiasis / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D016272:Occupational Health; D033661:Oocysts / Q000502:physiology; D011634:Public Health; D012307:Risk Factors; D012722:Sewage / Q000469:parasitology*; D034421:Sus scrofa; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000469:parasitology*; D014876:Water Pollution / Q000032:analysis
chemical_list: D012722:Sewage; D062065:Wastewater