Evaluation of Cryptosporidium parvum oocyst recovery efficiencies from various filtration cartridges by electrochemiluminescence assays

Genotypic characterization of Cryptosporidium hominis from water samples in Sao Paulo, Brazil

The protozoan parasite Cryptosporidium has emerged as one of the most important water contaminants, causing waterborne outbreaks of diarrheal diseases worldwide. The small size of oocysts under the microscope and the possibility of changes in characteristics of oocysts, mainly in environmental samples, make the taxonomy of the genus difficult if morphologic characteristics are considered. This limitation encouraged the application of molecular methods to identify this microorganism. The aim of this study was to detect and identify by nested-polymerase chain reaction oocysts of Cryptosporidium present in water samples in the state of São Paulo, Brazil. Water samples were concentrated through a membrane filter, DNA was extracted by using a standard technique, and both amplification reactions used forward and reverse oligonucleotides that were complementary to Cryptosporidium 18S ribosomal RNA gene sequences. Thirty water samples from different sites of collection in the state of São Paulo were evaluated. Cryptosporidium oocysts were detected in 30% of the samples. By genoptyping, C. hominis and Cryptosporidium sp. were identified in recreational water and C. meleagridis was identified in surface water samples. This is the first report of C. hominis in environmental samples in Brazil. Although identification of Cryptosporidium is still a difficult task, molecular methods are essential for specific identification and are a helpful tool to aid to understand the epidemiology of this parasite in Brazil.

Cross-flow microfiltration system for rapid enrichment of bacteria in water

Permanent monitoring of waterborne pathogens is important for securing the hygiene of water. Enumerating bacteria in water at low concentrations and minute quantities demands rapid and efficient enrichment methods in order to improve the signal-to-noise ratio of subsequent determination methods. In this work an automated cross-flow microfiltration (CFM) system is presented which is usable in the field to concentrate large volumes of environmental water for analytical purposes. It was designed as a rapid enrichment apparatus achieving high recovery and high concentration factors. The efficiency of the CFM system was studied for E. coli spiked in a 10-L tap water sample. By this technique, a 10-L water sample was concentrated by a factor of 200 in 15 min. The high and consistent recovery of 91.3 +/- 5.4% living cells in the concentration range 0.01 and 100 cfu mL(-1) is suitable for rapid enumeration of bacteria in water.

Occurrence of Giardia and Cryptosporidium in water supplies of Russia and Bulgaria

The aim of the present study was to investigate water supplies in southern Russia and Bulgaria, in order to estimate the occurrence of Giardia and Cryptosporidium in drinking water resources from these countries. A total of 166 water samples of different origin (surface, tap, bottled, well, spring and waste water) were collected from Rostov (southern Russia), Sofia and Varna (Bulgaria) Greater Areas and screened for the detection of Giardia cysts and Cryptosporidium oocysts. The method incorporated concentration of water samples by filtration and flocculation, sucrose purification, (oo)cyst detection/identification by immunofluorescence test and differential interference contrast. Sixteen out of 166 samples (9.6%) were positive for Giardia and 30 (18.1%) positive for Cryptosporidium. Both Giardia and Cryptosporidium were detected in tap, river, well and waste waters. Giardia cysts were additionally detected in bottled water. Particularly some river, waste and well water samples were highly contaminated with (oo)cysts. This study has shown that drinking water supplies in Russia and Bulgaria are subject to contamination with Giardia and Cryptosporidium, with potential hazards for the public health.

Portable continuous flow centrifugation and method 1623 for monitoring of waterborne protozoa from large volumes of various water matrices

AIMS

The aims of this study were to validate a portable continuous flow centrifuge (PCFC) as an alternative concentration step of US-EPA Method 1623 and to demonstrate it's efficacy for recovery of low numbers of protozoa from large volumes of various water matrices.

METHODS AND RESULTS

Recoveries of Cryptosporidium parvum oocysts, Giardia intestinalis cysts and Encephalitozoon intestinalis spores spiked into 10-1000 l volumes of various water matrices were evaluated during in-house and collaborative trials. Spiked protozoa were either approved standards or diluted stock samples enumerated according to USEPA Method 1623. Cryptosporidium recoveries exceeded method 1623 criteria and substantially high recoveries were observed for Giardia and E. intestinalis.

CONCLUSIONS

Portable continuous flow centrifuge methodology exceeded method 1623 acceptance criteria for Cryptosporidium and could be easily adopted for other protozoa.

SIGNIFICANCE AND IMPACT OF THE STUDY

The PCFC could be adopted as an alternative user-friendly concentration method for Cryptosporidium and for monitoring of large volumes of source and tap water for accidental or deliberate contamination with protozoa and potentially with other enteric pathogens. It is anticipated that PCFC would also be equal or superior to filtration for protozoa monitoring in wastewater and effluents.