Detection and quantification of viable<i>Ascaris</i>sp. and other helminth eggs in sewage sludge

Bastos, Veridiana Karmann; Cutolo, Silvana Audrá; Doria, Maria do Carmo Oliveira; Razzolini, María Tereza Pepe

doi:10.1080/09603123.2012.733939

Cited by 18 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Due to the higher prevalence rate, and ability to produce a higher number of ova each day by a female (Bethony et al, 2006;Brooker et al, 2006;Knopp et al, 2012) Dicrocoelium dendriticum have also been reported to be present in wastewater and sludge (Gaspard and Schwartzbrod, 2003;Mahvi and Kia, 2006;Do et al, 2007;Wichuk and McCartney, 2007;Jimenez et al, 2007;Ben Ayed et al, 2009;Kelessidis and Stasinakis, 2012;Bastos et al, 2013;Sharafi et al, 2012;Hajjami et al, 2012;Konate et al, 2013a;Konate et al, 2013b). Commonly detected helminth ova and larvae in the wastewater and sludge around the world, their mode of transmission and the infective stage are presented in The numbers of STHs ova in raw wastewater can be as high as 10 3 per liter depending upon the rate of infection in the community (Gaspard and Schwartzbord, 2003;Sharafi et al, 2012;Hajjami et al, 2012;Bastos et al, 2013). Climatic conditions such as temperature, rainfall, relative humidity can also influence the numbers of ova and larvae in the wastewater and sludge (Sharafi et al, 2012;Hajjami et al, 2012;Bastos et al, 2013).…”

Section: Prevalence Of Helminths In Wastewater and Sludgementioning

confidence: 99%

“…Commonly detected helminth ova and larvae in the wastewater and sludge around the world, their mode of transmission and the infective stage are presented in The numbers of STHs ova in raw wastewater can be as high as 10 3 per liter depending upon the rate of infection in the community (Gaspard and Schwartzbord, 2003;Sharafi et al, 2012;Hajjami et al, 2012;Bastos et al, 2013). Climatic conditions such as temperature, rainfall, relative humidity can also influence the numbers of ova and larvae in the wastewater and sludge (Sharafi et al, 2012;Hajjami et al, 2012;Bastos et al, 2013). This could be due to the fact that, STHs ova are known to develop faster at a temperature between 28-32ºC (Seamster, 1950;Beer, 1976;Smith and Schad, 1989;Brooker et al, 2006).…”

Section: Prevalence Of Helminths In Wastewater and Sludgementioning

confidence: 99%

“…This method, however, is laborious and time-consuming due to the requirement of multiple steps of blending, washing, settling, filtering, floating and centrifuging (Ferguson et al, 2004). The recovery rate of this method is reported as being suboptimal and variable depending on the matrices (65-74% and 26-82% from raw wastewater and sludge) (Bowman et al, 2003;Maya et al, 2006;Bastos et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Currently, detection and quantification of viable helminth ova from wastewater and sludge can be technologically difficult, labor intensive, time-consuming and expensive (Toze, 1999). Some of the existing methods considered as the more rapid and cheaper technologies to detect hookworm ova include the Kato-Katz, direct smear, thick smear and formalin-ethyl acetate methods (de Silva et al, 2006;Goodman et al, 2007;Cringoli et al, 2010;Habtamu et al, 2011;Bastos et al, 2013). These methods do not provide viability status of helminth ova.…”

Section: General Introductionmentioning

confidence: 99%

“…Several methods have also been used to recover various microorganisms including ova from water and soil samples. Those include centrifugation (Whitmore and Carrington, 1993;Higgins et al, 2003), hollow-fiber ultrafiltration (HFUF) (Simmons et al, 2001;Ferguson et al, 2004;Hill et al, 2005;Hill et al, 2007), filtration (Nieminski et al, 1995;Maya et al, 2006;Alli et al, 2011), and flotation (US EPA, 1999;Bowman et al, 2003;de Victorica and Galván, 2003;Bastos et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Detection of viable hookworm ova from wastewater and sludge

Gyawali¹

View full text Add to dashboard Cite

Infectious helminths are a worldwide major public health problem. In terms of morbidity, approximately 3 × 10 9 people are infected by soil-transmitted helminths (STHs) influencing rates of malnutrition and failure to thrive. All of this increases the global disease burden (GDB) by up to 5.9 × 10 6 Daily Adjusted Life Years (DALYs). Helminth infections are more often seen as a major public health issue for developing countries however, concerns have been expressed in many of the developed nations because of the increased use of treated wastewater and sludge with no clear way of knowing the infection potential that can be attributed from such water.Guidelines have been established to minimise the potential public health risk associated with wastewater and sludge reuse. For example, the WHO guideline specified ≤ 1 ova (Ascaris lumbricoides) per L liquid (wastewater) or 4 g dry solid (sludge) for unrestricted use. Various wastewater treatment processes have been recommended to remove the helminths ova from wastewater depending upon its reuse. However, detection methods used to quantify viable helminths ova from wastewater has limitations. Therefore there is always a potential public health risk associated with reuse of wastewater and sludge.In this research, a real-time PCR method was developed. The new PCR method is rapid and specific. The method was found to be able to detect less than one ovum in one litre treated wastewater and approximately four ova in one litre raw wastewater and ~ 4 g sludge.The real-time PCR method was modified to a quantitative PCR (qPCR) method and further used to quantify hookworm ova from wastewater and sludge. The qPCR had estimated an average of 1.1, 8.6 and 67.3 ova for treated wastewater that was seeded with 1, 10 and 100 ova, respectively. The gene copy numbers obtained for 1, 10 and 100 ova by qPCR varied significantly (P < 0.05) within the tested samples indicating that absolute quantification of ova may not be accurate. Despite the difficulty quantifying accurate numbers of hookworm ova, the lower limit of quantification (LLOQ) of the qPCR method was 30 gene copies. This was a lot less than the gene copies produced by one ovum. Therefore, the qPCR method has potential to use for complying with wastewater guidelines.. iiAlthough the overall aim of this research was to develop a sensitive and specific method for quantitative detection of viable hookworm ova from wastewater, the importance of recovering the ova from wastewater and sludge samples for accurate detection was identified. While determining appropriate recovery rates was not an aim of this research, a suitable method that could be used to standardise research outcomes for further study was established. Therefore, ova recovery rate by different rapid methods was evaluated for further experiments. The result indicated that the ova recovery rate was higher for the treated wastewater (0.2 -50%) than the raw wastewater (0.3 -35%) and sludge (0.02 -4.7%) samples. A significant difference (P < 0.05) was observed between...

show abstract

Section: Prevalence Of Helminths In Wastewater and Sludgementioning

confidence: 99%

Section: Prevalence Of Helminths In Wastewater and Sludgementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: General Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Detection of viable hookworm ova from wastewater and sludge

Gyawali¹

View full text Add to dashboard Cite

show abstract

Detection and quantification of soil-transmitted helminths in environmental samples: A review of current state-of-the-art and future perspectives

et al. 2017

View full text Add to dashboard Cite

It is estimated that over a billion people are infected with soil-transmitted helminths (STHs) globally with majority occurring in tropical and subtropical regions of the world. The roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworms (Ancylostoma duodenale and Necator americanus) are the main species infecting people. These infections are mostly gained through exposure to faecally contaminated water, soil or contaminated food and with an increase in the risk of infections due to wastewater and sludge reuse in agriculture. Different methods have been developed for the detection and quantification of STHs eggs in environmental samples. However, there is a lack of a universally accepted technique which creates a challenge for comparative assessments of helminths egg concentrations both in different samples matrices as well as between locations. This review presents a comparison of reported methodologies for the detection of STHs eggs, an assessment of the relative performance of available detection methods and a discussion of new emerging techniques that could be applied for detection and quantification. It is based on a literature search using PubMed and Science Direct considering all geographical locations. Original research articles were selected based on their methodology and results sections. Methods reported in these articles were grouped into conventional, molecular and emerging techniques, the main steps in each method were then compared and discussed. The inclusion of a dissociation step aimed at detaching helminth eggs from particulate matter was found to improve the recovery of eggs. Additionally the selection and application of flotation solutions that take into account the relative densities of the eggs of different species of STHs also results in higher egg recovery. Generally the use of conventional methods was shown to be laborious and time consuming and prone to human error. The alternate use of nucleic acid-based techniques has improved the sensitivity of detection and made species specific identification possible. However, these nucleic acid based methods are expensive and less suitable in regions with limited resources and skill. The loop mediated isothermal amplification method shows promise for application in these settings due to its simplicity and use of basic equipment. In addition, the development of imaging soft-ware for the detection and quantification of STHs shows promise to further reduce human error associated with the analysis of environmental samples. It may be concluded that there is a need to comparatively assess the performance of different methods to determine their applicability in different settings as well as for use with different sample matrices (wastewater, sludge, compost, soil, vegetables etc.).

show abstract