Persistence ofGiardia,Cryptosporidium,Rotavirus,andAdenovirusin Treated Sewage in São Paulo State, Brazil

Abstract

: The persistence of Giardia, Cryptosporidium, Rotavirus, and Adenovirus in samples of raw and treated sewage collected monthly in 2010 at the Biological Wastewater Treatment Plant of Ribeirão Preto, SP, Brazil, was analyzed. The USEPA Method 1623 was used to detect and quantify Giardia and Cryptosporidium. An enzyme immunoassay was carried out to test Rotavirus and Adenovirus antigen optical density (Rotascreen® and Adenoscreen®). The results show a significant decrease in the concentrations of Giardia, Rotavirus and Adenovirus (P < 0.05) and a trend of decreasing Cryptosporidium densities, without statistical significance. Giardia concentrations ranged from 120 to 2,200 cysts/L in raw sewage and from 0.45 to 3.5 cysts/L in treated sewage. Cryptosporidium concentration ranged from undetectable to 28.9 oocysts/L in raw sewage and undetectable to 1.05 oocysts/L in treated sewage. Rotavirus presented absorbance values that ranged from 1.17 ± 0.81 in raw sewage to 0.46 ± 0.32 in treated sewage. Adenovirus, in turn, presented absorbance values of 0.64 ± 0.20 in raw sewage and of 0.45 ± 0.04 in treated sewage. There was no significant seasonal tendency observed in the distribution of protozoa (oo)cysts and in the viral antigen density in the monthly sewage samples during 2010 (P > 0.05). Even though these pathogenic agents decreased after treatment, the remaining loads observed in treated sewage can reach the watercourses receiving it. Giardia, Cryptosporidium, Rotavirus, and Adenovirus are pathogens with very low infectious doses, representing a public health risk especially for vulnerable groups, such as children living near these watercourses and homeless people using this water for various purposes. Studies addressing the environmental persistence of opportunistic pathogens in watercourses are hugely important in the public health sphere, especially in developing countries, where economic, social, cultural, and environmental factors still persist that are favorable to population's exposure to diarrhea-causing agents.

Reuse of Treated Sewage Effluent (TSE) in Qatar

“…These facts highlight the shortfalls of treatment plants in adequately addressing the risk associated with pathogens. Tonani et al reported that although remarkable removal rate were achieved for Cryptosporidium, Giardia, Rotavirus and Adenovirus in the wastewater effluent, the breakthrough of the remaining pathogens can still be harmful for children [58]. Similar findings [59] were observed in a membrane bio-reactor (MBR) treated wastewater that was used for agricultural irrigation.…”

Adenovírus e rotavírus em águas superficiais do córrego Ribeirão Preto, São Paulo, Brasil

“…De acordo com a Ambient 25 , a cidade despeja aproximadamente 50 milhões m3/ano de esgoto tratado nas águas do córrego Ribeirão Preto. Dessa forma, é possível que este efluente esteja influenciando os resultados, visto que processos de tratamento de esgoto por lodos ativados não são totalmente eficientes na remoção de adenovírus e rotavírus, corroborando com os resultados encontrado por Tonani et al 9 .…”

“…Cabe destacar que em um estudo recente realizado por Tonani et al 9 , foi detectado a presença de adenovírus e rotavírus em esgoto bruto e tratado da ETE de Ribeirão Preto, SP., nos alertando para a possível circulação desses patógenos virais na população. Cabe destacar que relatos divulgados na imprensa da cidade mostram que a população do município utiliza as águas do córrego Ribeirão Preto para higiene pessoal, lazer e dessedentação de animais colocando a população em contato direto ou indireto à diversos contaminantes ambientais 14 .…”

“…Umas das grandes preocupações no contexto da saúde pública se deve à baixa dose de vírus entéricos necessária para causar infecção em hospedeiros humanos, bem como, a gravidade da morbidade em indivíduos imunossuprimidos, idosos e crianças 7,8 . Além disso, a disseminação de vírus entéricos em ambientes aquáticos localizados no espaço urbano é preocupante, considerando a persistência ambiental desses agentes e a resistência que apresentam a processos convencionais de tratamento de água e esgoto 8,9 . Os vírus entéricos atingem as águas superficiais especialmente por meio do lançamento de efluentes domésticos e agropecuários, uma vez que, são eliminados em altas concentrações nas fezes de humanos e animais infectados 10,11 .…”

Comparison of Two Virus Concentration Methods for Enteric Viruses Detection in Moroccan Wastewater and Treated Effluent

“…According to public health data, those types can colonize the gastrointestinal tracts and cause a wide variety of illnesses, inducing variable epidemiological features and some water-related diseases (3) . EV, HAV, HEV, HAdV, HuNoV, RV and HAstV have been detected in raw wastewater and treated effluent in different studies (4)(5)(6)(7)(8)(9) .…”