28
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Survival of Ascaris eggs and hygienic quality of human excreta in Vietnamese composting latrines

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          For centuries farmers in Vietnam have fertilized their fields with human excreta collected directly from their household latrines. Contrary to the official guideline of six-month storage, the households usually only store human excreta for three to four months before use, since this is the length of time that farmers have available to produce fertilizer between two cropping seasons. This study aimed to investigate whether hygienically safe fertilizer could be produced in the latrines within this period of time.

          Methods

          By inoculating eggs of the helminth parasite indicator Ascaris suum into heaps of human excreta, a die-off experiment was conducted under conditions similar to those commonly used in Vietnamese latrines. Half a ton of human excreta was divided into five heaps containing increasing concentrations of lime from 0% to 11%.

          Results

          Regardless of the starting pH, which varied from 9.4 to 11.6, a >99% die-off of eggs was obtained after 105 to 117 days of storage for all lime concentrations and 97% of eggs were non-viable after 88 days of storage. The most critical parameter found to determine the die-off process was the amount of ammonia (urine) in the excreta which indicates that longer storage periods are needed for parasite egg die-off if urine is separated from the excreta.

          Conclusion

          By inactivating >99% of all A. suum eggs in human excreta during a storage period of only three months the commonly used Double Vault Composting (DVC) latrine, in which urine is not separated, could therefore potentially provide a hygienic acceptable fertilizer.

          Related collections

          Most cited references13

          • Record: found
          • Abstract: found
          • Article: not found

          The public health significance of Trichuris trichiura.

          An estimated 1049 million persons harbour T. trichiura, including 114 million preschool-age children and 233 million school-age children. The prevalence of T. trichiura is high and may reach 95% in children in many parts of the world where protein energy malnutrition and anaemias are also prevalent and access to medical care and educational opportunities is often limited. The Trichuris dysentery syndrome (TDS) associated with heavy T. trichiura, which includes chronic dysentery, rectal prolapse, anaemia, poor growth, and clubbing of the fingers constitutes an important public health problem, as do lighter but still heavy infections, even if not strictly TDS, especially in children. The profound growth stunting in TDS can be reversed by repeated treatment for the infection and, initially, oral iron. However findings from Jamaica strongly suggest that the significant developmental and cognitive deficits seen are unlikely to disappear without increasing the positive psychological stimulation in the child's environment. The severe stunting in TDS now appears likely to be a reaction at least in part to a chronic inflammatory response and concomitant decreases in plasma insulin-like growth factor-1 (IGF-1), increases in tumor necrosis factor-alpha (TNF-alpha) in the lamina propria of the colonic mucosa and peripheral blood (which likely decrease appetite and intake of all nutrients) and a decrease in collagen synthesis. Improvements in cognitive performance have been found after treatment for relatively heavy infections (without chronic dysentery) in school-going children; it is unclear precisely how much T. trichiura interferes with children's ability to access educational opportunities, but treatment of infections whenever possible is obviously sensible. The blood loss that can occur in T. trichiura infection is likely to contribute to anaemia, particularly if the child also harbours hookworm, malaria and/or has a low intake of dietary iron. Community control is important, particularly for the individuals within a population who harbour heavy worm burdens; this means children, with special attention to girls who will experience increased iron requirements and blood loss due to menstruation, pregnancies, and lactation. Mebendazole and albendazole, both of which are on the WHO Essential Drugs List, are very effective against T. trichiura; multiple doses are needed to attain complete parasitological cure in all cases. However the goal of control programmes in endemic areas is morbidity reduction, which follows when intensity of infection is significantly reduced.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Urban/rural differences in prevalence and risk factors for intestinal helminth infection in southern Malawi.

            Urbanization may increase the risk of human infection with intestinal helminths. A cross-sectional survey was conducted to investigate the prevalence, intensity and potential risk factors of acquiring such infection, among children aged 3-14 years in similar urban and rural communities in southern Malawi. Stool samples were collected from 553 children (273 urban and 280 rural). The overall prevalence of helminth infection was significantly higher in the urban subjects than in the rural (16.5% v. 3.6%; P < 0.001), mostly because of differences in the prevalence of Ascaris lumbricoides infection. Living in an urban community was associated with a significantly higher risk of infection [odds ratio (OR) = 5.3; 95% confidence interval (CI) = 2.6-12.1], even after controlling for potential confounding factors. In the urban community, risk factors included having pools of water/sewage around houses (OR = 3.0; CI = 1.4-6.5), not wearing shoes (OR = 7.1; CI = 2.7-19.2), not attending school (OR = 2.8; CI = 1.2-6.5), having mothers with 4-8 years of education (OR = 5.2; CI = 2.0-14.0), and having mothers below 35 years of age (OR = 4.09; CI = 1.39-16.28). In this part of Africa, efforts to reduce helminth infections may best be focused on reducing geohelminth burden in urban areas.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The effects of temperature, pH, and ammonia concentration on the inactivation of Ascaris eggs in sewage sludge.

              The reported inactivation of Ascaris eggs during alkaline sludge stabilization is highly variable. The objective of our research was to better understand the sources of this variability by quantifying the effects of temperature, pH, and ammonia concentration on the inactivation of indigenous Ascaris eggs in wastewater sludge. Primary sludge was supplemented with ammonia (0, 1000, and 5000 mg/l NH(3)-N) and Ca(OH)(2) and incubated in sealed bottles across the range of temperatures (20, 30, 40, and 50 degrees C) and pH (7 and 12) that may be encountered during treatment. Changes in egg viability over time were fit to a two-parameter kinetic model (shoulder and first-order region); to compare treatment conditions, the time for 99% inactivation (t(99)) was also calculated. Each 10 degrees C increase in temperature caused a significant decrease in t(99) at every pH and ammonia concentration tested. At 50 degrees C, the effect of temperature was dominant, such that no effect of pH or ammonia was observed. At 30 and 40 degrees C, raising the pH from 7 to 12 decreased t(99), but at 20 degrees C no pH effect was seen over 80 d (very little inactivation occurred). At 20, 30, and 40 degrees C, the addition of ammonia dramatically decreased t(99). The effect of pH could not be completely separated from that of ammonia, as the unamended sludge samples contained 100-200mg/l indigenous ammonia. Because temperature, pH, and ammonia all contributed to Ascaris egg inactivation, it is essential that these parameters are measured and accounted for when assessing the effectiveness of alkaline stabilization. Furthermore, inactivation by ammonia could be exploited to improve the effectiveness of alkaline sludge stabilization.
                Bookmark

                Author and article information

                Journal
                Environ Health
                Environmental Health
                BioMed Central
                1476-069X
                2009
                16 December 2009
                : 8
                : 57
                Affiliations
                [1 ]Department of International Health, Immunology and Microbiology, Faculty of Health, University of Copenhagen, Øster Farimagsgade 5. PO Box 2099.1014, Copenhagen K, Denmark
                [2 ]National Institute of Hygiene and Epidemiology, Division of Enteric Infections, 1 Yersin Street, Hanoi, Vietnam
                [3 ]National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1790, Copenhagen V, Denmark
                [4 ]Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Groennegaardsvej 15, DK-1870 Frederiksberg C, Denmark
                Article
                1476-069X-8-57
                10.1186/1476-069X-8-57
                2804663
                20003550
                87795f83-2fd3-4afa-96df-bbfe1a6e51b0
                Copyright ©2009 Jensen et al; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 26 June 2009
                : 16 December 2009
                Categories
                Research

                Public health
                Public health

                Comments

                Comment on this article