Soil‐transmitted helminth infections associated with wastewater and sludge reuse: a review of current evidence

Abstract

ObjectiveTo review current evidence on infections related to the concentration of soil‐transmitted helminth (STH) eggs in wastewater, sludge and vegetables irrigated with wastewater or grown on sludge‐amended soils.MethodSearch of Web of Science, Science Direct, PubMed and Google Scholar databases for publications reporting on STH egg concentration in wastewater, sludge and vegetables and for epidemiological studies on wastewater/sludge reuse and STH infections.Results STH egg concentrations were variable but high in wastewater and sludge especially in developing countries. They ranged from 6 to 16 000 eggs/L in wastewater and from 0 to 23 000 eggs/g in sludge and far exceed limits set in the WHO guideline for wastewater/sludge reuse. Numbers of STH eggs on vegetables ranged from 0 to 100 eggs/g. The concentration of STH eggs in wastewater, sludge and vegetables therefore relates to risks of infection through different exposure routes.ConclusionEpidemiological evidence reveals an increased prevalence of STH infections associated with direct exposure to wastewater or sludge (farmers) and consumption of vegetables grown on soil treated with it. This calls for increased efforts to reduce the adverse health impact of wastewater and sludge reuse in line with the WHO multi‐barrier approach.

Chlorination of Schistosoma mansoni cercariae

“…Therefore, a 2-log inactivation may be sufficient to inactivate all cercariae. This is unlike wastewater treatment where helminth eggs are found in much higher concentrations and therefore require higher log inactivations [40]. For example, water with a concentration of less than 1 cercaria/ 100L (as found in the field on St Lucia [41]) would enable the safe treatment of up to 10,000L, as this volume would contain less than 100 cercariae.…”

Biological HRPs in wastewater

“…The eggs lay by most nematodes that are parasitic in humans may include either the zygote, blastomere, or formed larva (Castro, 1996). The concentration of helminth eggs was high in wastewater and sludge, especially in developing countries (Amoah et al, 2018). The soil-transmitted helminth eggs relate to infection risk through different exposure routes.…”

Application of electron beam water radiolysis for sewage sludge treatment—a review

“…hand, foot and mouth disease, poliomyelitis, Bornholm disease, polio-like syndrome, pericarditis, myocarditis A total of 57,628 cases occurred with 3,145 deaths and 21,269 paralysed patients, in 1952, in the United States Zamula ( 1991 ) Vibrio cholerae Cholera A total of 1,041,422 cases occurred with 9642 deaths in 1991 in America Skowron et al ( 2018 ) Clostridia (mostly C. perfringens ) Type A food poisoning, necrotising enteritis, enterotoxaemias, bacteraemia, gas gangrene Widely distributed in the soil and in faeces of humans and animals, dominant cause of food poisoning in the USA and Canada Labbe and Juneja ( 2017 ), McClane ( 2014 ) Cryptococcus (mostly Cryptococcus neoformans ) Meningitis, meningoencephalitis or disseminated disease Major life-threatening fungal infection in patients with severe HIV infection, may complicate organ transplantation, reticuloendothelial malignancy, corticosteroid treatment or sarcoidosis Kaplan et al ( 2002 ) Roundworms (mostly Ascaris lumbricoides ) Helminthiasis (incl. soil-transmitted): ascariasis, necatoriasis, cestodiasis, also malnutrition, anaemia, and others Ascariasis classified as the most prevailing parasitic infection, about 1/5 of the world’s population affected Amoah et al ( 2018 ), Vieira Da Rocha et al ( 2016 ) Giardia ( G. lamblia ) Giardiasis, severe diarrhoea About 1/3 of the developing countries population affected, from 3 to 7% of people affected in the USA Auerbach ( 2011 ) …”