Pre-ozonation of source water: Assessment of efficacy against Giardia duodenalis cysts and effects on natural organic matter.

The protozoan Giardia duodenalis is one of the parasites of primary concern in drinking water treatment plants, due to its resistance to chlorination. Another matter of concern regarding chlorination of drinking water is the formation of disinfection by-products in the presence of precursors such as natural organic matter (NOM). In this study, the effects of ozonation (5 mg L-1) on G. duodenalis cysts in raw surface water from a drinking water treatment plant were evaluated, and the presence and alteration of NOM were assessed, as an indicative of the potential to prevent total organic halogen (TOX) formation during post-chlorination. Following ozone treatment, the presence of damaged cysts was observed by direct immunofluorescence assay (IFA) and confirmed by the molecular approach propidium monoazide-polymerase chain reaction (PMA-PCR). Using an animal model, analysis of the intestinal tissues revealed that 80% of the animals inoculated with ozonated water were positive for trophozoites. This study shows that analysis of intestinal fragments is imperative to accurately assess animal infection following inoculation of treated cysts. More importantly, considering the low infective dose of Giardia cysts in susceptible hosts, an ozone dosage usually applied in drinking water treatment plants did not completely inactivate G. duodenalis cysts in surface water. Nonetheless, the results suggest that competitive reactions with NOM have occurred, and the applied ozone dosage has proven useful to remove NOM reactivity, and thus prevent halogenated DBP formation during post-chlorination.

Giardia duodenalis: Number and Fluorescence Reduction Caused by the Advanced Oxidation Process (H2O2/UV).

This study evaluated the effect of peroxidation assisted by ultraviolet radiation (H2O2/UV), which is an advanced oxidation process (AOP), on Giardia duodenalis cysts. The cysts were inoculated in synthetic and surface water using a concentration of 12 g H2O2 L(-1) and a UV dose (λ = 254 nm) of 5,480 mJcm(-2). The aqueous solutions were concentrated using membrane filtration, and the organisms were observed using a direct immunofluorescence assay (IFA). The AOP was effective in reducing the number of G. duodenalis cysts in synthetic and surface water and was most effective in reducing the fluorescence of the cyst walls that were present in the surface water. The AOP showed a higher deleterious potential for G. duodenalis cysts than either peroxidation (H2O2) or photolysis (UV) processes alone.

Infectivity of Giardia duodenalis Cysts from UV Light-Disinfected Wastewater Effluent Using a Nude BALB/c Mouse Model.

Giardia duodenalis is a protozoan of public health interest that causes gastroenteritis in humans and other animals. In the city of Campinas in southeast Brazil, giardiasis is endemic, and this pathogen is detected at high concentrations in wastewater effluents, which are potential reservoirs for transmission. The Samambaia wastewater treatment plant (WWTP) in the city of Campinas employs an activated sludge system for sewage treatment and ultraviolet (UV) light for disinfection of effluents. To evaluate this disinfection process with respect to inactivating G. duodenalis cysts, two sample types were investigated: (i) effluent without UV disinfection (EFL) and (ii) effluent with UV disinfection (EFL+UV). Nude immunodeficient BALB/c mice were intragastrically inoculated with a mean dose of 14 cysts of G. duodenalis recovered from effluent from this WWTP, EFL, or EFL+UV. All animals inoculated with G. duodenalis cysts developed the infection, but animals inoculated with UV-exposed cysts released a lower average concentration of cysts in their faeces than animals inoculated with cysts that were not UV disinfected. Trophozoites were also observed in both groups of animals. These findings suggest that G. duodenalis cysts exposed to UV light were damaged but were still able to cause infection.

Detecção de oocistos de Cryptosporidium spp. e cistos de Giardia spp. em amostras de esgoto bruto ou tratado: avaliação crítica dos métodos / Detection of Cryptosporidium spp. oocysts and Giardia spp. cysts in raw and effluent wastewater: critical evaluation of methods

Neste trabalho, avaliou-se a eficiência dos métodos centrífugo-concentração e filtração em membrana, na detecção de oocistos de Cryptosporidium spp. e cistos de Giardia spp. em amostras de esgoto bruto e tratado, provenientes de um sistema de lodos ativados (estação de tratamento de esgoto, Samambaia, Campinas, em São Paulo). As amostras foram coletadas quinzenalmente por dois anos: 53 amostras de esgoto bruto (AFL), 53 de efluente tratado sem desinfecção por luz ultravioleta (EFL) e 38 de efluente tratado e desinfetado por luz ultravioleta (EFL+UV). Cistos de Giardia spp. foram encontrados em 90,5 por cento das amostras AFL; em 96,2 por cento, de EFL; e em 94,7 por cento, de EFL+UV. Oocistos de Cryptosporidium spp. foram detectados em 6,4 por cento das amostras AFL e em 2,6 por cento de EFL+UV. Ambos os métodos mostraram-se eficientes na detecção destes protozoários em todos os tipos de amostras, além de apresentarem baixo custo por análise.

In this study, the efficiency of centrifuge-concentration and membrane filtrated methods was evaluated in the detection of Cryptosporidium spp. oocysts and Giardia spp. cysts in raw or treated wastewater samples, from activated sludge systems (ETE - Samambaia, Campinas, in São Paulo). The samples were collected once a fortnight for two years: 53 samples of influent (AFL), 53 samples of treated effluent without ultraviolet disinfection (EFL), and 38 samples of treated effluent with ultraviolet disinfection (EFL+UV). Giardia spp. cysts were found in 90.5 percent of the AFL samples; in 96.2 percent of the samples, EFL; and in 94.7 percent, EFL+UV. Cryptosporidium spp. oocysts were detected in 6.4 percent of AFL samples and 2.6 percent of EFL+UV. Both methods showed efficiency when detecting protozoa in all types of samples, besides having low costs by analysis.

Cryptosporidium spp. and Giardia spp. in surface water supply of Campinas, southeast Brazil.

Surface water contaminated by domestic sewage discharges is a potential source of pathogens, including protozoa. During 2005-2006, the source water (Atibaia River) of the Surface Water Treatment Plant (WTP) of Campinas city, São Paulo, Brazil was sampled to obtain an assessment of Cryptosporidium oocyst and Giardia cyst concentrations. Calcium carbonate flocculation (CCF) and membrane filtration (MF) concentration techniques, with and without purification by immunomagnetic separation (IMS) were evaluated. The cysts and oocysts were detected by immunofluorescence assay (IFA) and confirmed by differential interference contrast (DIC). Membrane filtration method generally produced higher recovery efficiency. Giardia spp. was detected in 87.5% of the water samples analyzed with densities ranging from 2.5 to 120 cysts per L. Cryptosporidium spp were detected in 62.5% and the concentrations ranged from 15 to 60 oocysts per L. Cryptosporidium oocyst and Giardia cyst concentrations detected in this study were elevated and are associated with discharge of untreated sewage in Atibaia River. Measures should be taken to protect surface water from sources of contamination.

Occurrence of Giardia cysts and Cryptosporidium oocysts in activated sludge samples in Campinas, SP, Brazil

Giardia e Cryptosporidium causaram vários surtos epidêmicos de gastroenterite, associados à água potável. Efluentes de esgoto contaminados foram incriminados como uma fonte potencial de cistos e oocistos. Uma investigação foi conduzida para verificar a presença de cistos de Giardia e oocistos de Cryptosporidium em amostras de lodo ativado de uma Estação de Tratamento de Esgoto. Para isto as amostras foram submetidas: i) a concentração pelo processo de clarificação com éter (ECP) e ii) método de purificação por flutuação em sacarose (SFM) e, as alíquotas dos sedimentos foram examinadas por imunofluorescência. Cistos de Giardia estiveram presentes em todas as amostras avaliadas (100,0%; n = 8) quando utilizado ECP e kit 1, enquanto o kit 2 resultou em 6 amostras positivas (85,7%; n = 7). Para SFM, cistos de Giardia foram detectados em 75,0% e 100,0% destas amostras (para kit 1 e 2 respectivamente). Considerando os oocistos de Cryptosporidium, duas amostras (25,0%; kit 1 e 28,5% kit 2) foram positivas usando-se ECP enquanto para SFM, apenas uma amostra (examinada pelo kit 1) foi positiva (12,5%). Os resultados do experimento-controle revelaram que as taxas de recuperação para Giardia e Cryptosporidium, quando utilizado ECP foi de 54,5% e 9,6% e para SFM, foi de 10,5% e 3,2%, respectivamente. Considerando a detecção de alta concentração desses protozoários, é recomendada a avaliação prévia do lodo ativado antes de sua aplicação na agricultura e, com alguma melhora, ECP pode ser uma técnica apropriada e simples para a detecção de protozoários em amostras de esgoto.

Occurrence of Giardia cysts and Cryptosporidium oocysts in activated sludge samples in Campinas, SP, Brazil.

Giardia and Cryptosporidium have caused several outbreaks of gastroenteritis in humans associated with drinking water. Contaminated sewage effluents are recognized as a potential source of waterborne protozoa. Due to the lack of studies about the occurrence of these parasites in sewage samples in Brazil, we compared the efficiency of two procedures for concentrating cysts and oocysts in activated sludge samples of one sewage treatment plant. For this, the samples were submitted to i) concentration by the ether clarification procedure (ECP) and to ii) purification by sucrose flotation method (SFM) and aliquots of the pellets were examined by immunofluorescence. Giardia cysts were present in all samples (100.0%; n = 8) when using ECP and kit 1 reagents, while kit 2 resulted in six positive samples (85.7%; n = 7). As for SFM, cysts were detected in 75.0% and 100.0% of these samples (for kit 1 and 2, respectively). Regarding Cryptosporidium, two samples (25.0%; kit 1 and 28.5% for kit 2) were detected positive by using ECP, while for SFM, only one sample (examined by kit 1) was positive (12.5%). The results of the control trial revealed Giardia and Cryptosporidium recovery efficiency rates for ECP of 54.5% and 9.6%, while SFM was 10.5% and 3.2%, respectively. Considering the high concentration detected, a previous evaluation of the activated sludge before its application in agriculture is recommended and with some improvement, ECP would be an appropriate simple technique for protozoa detection in sewage samples.

Avaliação de um inseto alternativo para a triagem preliminar de pediculicidas potenciais / Evaluation of an alternative insect for the preliminary screening of potencial pediculicides

A necessidade de constantes avaliações de novos produtos para o controle do piolho da cabeça e a dificuldade na sua obtenção e manutenção em laboratório estimula a busca de alternativas. No presente trabalho discute-se o uso do besouro Lasioderma serricorne (F.) para se avaliar previamente a toxicidade tópica de fórmulas de creme rinse ou xampu. Foram testados dois produtos comerciais creme rinse à base de permetrina, um deles com (Toppyc) ou sem (Kwell) butóxido de piperonila. Os resultados indicam que L. serricorne poderia ser usado em ensaios comparativos de laboratório com vantagens quanto a se obter e criar essa espécie.

Survey of cyclopids (Crustacea, Copepoda) in Brazil and preliminary screening of their potential as dengue vector predators

Copépodos ciclopídeos säo conhecidos como bons controladores de mosquitos, especialmente quando considerado as larvas dos vetores da dengue Aedes aegypti e Ae. Albopictus. Onze corpos d'água em CAmpinas, SP, Brasil, foram avaliados para copépodos coletando-se 1,5 l de água de cada um deles. O potencial predador dos copépodos adultos foi avaliado por 24 h, em laboratório, em grupos de 5 indivíduos predadando sobre 30 larvas de 1§ estádio de Ae. albopictus. No presente levantamento, as seguintes espécies de ciclopídeos foram encontradas: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus e Mesocyclops longisetus var. longisetus. O potencial predador desses copépodos variou de zero a 97,3 por cento. A amostra coletada no campo contendo apenas com M. longisetus var. longisetus mostrou a melhor eficiência de controle, sem diferença significativa de uma cultura de laboratório (ML-01) criada por 3 anos, desta mesma espécie, que foi avaliada para comparaçäo. A amostra com poucos M. albidus var. albidus foi cotada em segundo melhor lugar, apresentando em média 25,9 por cento de eficiência. O uso de copépodos em pneus armadilha como controladores dos vetores da dengue é discutido