|BRIEF RESEARCH ARTICLE
|Year : 2018 | Volume
| Issue : 3 | Page : 227-230
Water, sanitation and hygiene survey – Use of hydrogen sulfide strip at field level as a point-of-care test: A pilot study
PV Shilpa1, Madhavi Bhargava2
1 Undergraduate Medical Student, Yenepoya Medical College, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
2 Assistant Professor, Department of Community Medicine, Yenepoya Medical College, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
|Date of Web Publication||12-Sep-2018|
Department of Community Medicine, Yenepoya Medical College, Yenepoya (Deemed to be University), Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Safe drinking water is a basic element of primary health care. The government of India in its Indian Public Health Standards recommends the hydrogen sulfide (H2S) strip test as a desirable component at primary health centers for screening water for fecal coliforms. The objective of the present study was to conduct a water, sanitation and hygiene (WASH) survey followed by a H2S strip test of drinking water in a village with ninety households. The test was positive in 88% at the source and the point of consumption, with 100% concordance between both the points of test. A subsample of water samples was subjected to testing in microbiology laboratory, and fecal contamination was confirmed in all of them. To conclude, H2S strip test can be conveniently used at field level, and its ease of use and visual nature of results make it a useful point-of-care test of environmental and public health.
Keywords: Hydrogen sulfide strip test, point-of-care test, water, sanitation and hygiene, water testing
|How to cite this article:|
Shilpa P V, Bhargava M. Water, sanitation and hygiene survey – Use of hydrogen sulfide strip at field level as a point-of-care test: A pilot study. Indian J Public Health 2018;62:227-30
|How to cite this URL:|
Shilpa P V, Bhargava M. Water, sanitation and hygiene survey – Use of hydrogen sulfide strip at field level as a point-of-care test: A pilot study. Indian J Public Health [serial online] 2018 [cited 2019 May 22];62:227-30. Available from: http://www.ijph.in/text.asp?2018/62/3/227/241102
Water, sanitation and hygiene (WASH) are important environmental determinants of health. Earlier, the Millennium Development Goals and now recently the Sustainable Development Goals include safe water and sanitation., According to the National Family Health Survey – 4 (NFHS-4), households with an improved source of drinking water and sanitation facility are 88.9% and 42%, respectively. Wells are a common source of drinking water in the Dakshina Kannada district of Karnataka.
Hydrogen sulfide (H2S) paper-strip test, a low-cost test for detecting fecal contamination in drinking water, was developed at Defence Research and Development Organization, India, in 1982. It is based on the principle that bacteria due to fecal contamination produce H2S. The test uses thiosulfate as a source of sulfur and ferric ammonium citrate as an indicator. H2S is produced by the reduction of thiosulfate by enteric bacteria which react with the ferric salt to form an insoluble black ferrous sulfide precipitate. Reliability of the H2S test has been done for its ability to detect minimum level of fecal coliforms., A multicountry intercomparison study found that it is an ideal tool for testing rural drinking water. The field evaluation of H2S test was done by analyzing 1050 water samples from various sources at room temperature and at 37°C in India with good results. It is easy to use (incubated at room temperature) and interpret (uses color change as an indicator of contamination).
It is a “desirable” component in primary health centers (PHCs) according to the Indian Public Health Standards (IPHS). But unfortunately, it continues to remain much desired and is usually not available at the PHCs in India.
The present study was done to assess WASH practices in the residents of a village and test drinking water at the source and at the point of consumption using H2S strip test.
This was an observational cross-sectional study done during June and July months of 2016 in a village of about ninety households (population of 420) in the coastal area of Dakshina Kannada, Karnataka. The village was purposively selected as a part of National Service Scheme student adoption program. A need and feasibility assessment was done by an initial visit. The following important points were noted:
- It was a small village with one overhead tank
- There were many wells; wells were the preferred source of drinking water
- Panchayat, accredited social health activists, and anganwadi workers (AWWs) were ready to facilitate the activity and did not remember when the water of the overhead tank was last tested
- Diarrhea and febrile illnesses were reported in some seasons by the AWW.
A questionnaire based on NFHS-4 survey tool and core questions from the WHO and UNICEF work on drinking water and sanitation for household surveys was prepared in the local language. The study process had essentially three steps: interview schedule, testing of the water from source and at the point of consumption, and, lastly, reading and interpretation of results at a specified interval, which is described in [Figure 1]. Written informed consent was taken from the adult member of the households present during the survey. Ethical clearance was taken from the Institutional Ethics Committee (letter no: YUEC 260/2016).
|Figure 1: Water with fecal contamination turns black with hydrogen sulfide strip test.|
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The water source for the household was identified and water was collected for the H2S strip test bottle from the source and point of consumption within the households. The bottles were labeled, the interviewee was explained about incubation of the test bottle at room temperature within the house, and a second visit after 24–36 h was made to examine the color change of the water as depicted in [Figure 1].
H2S test of water: Fecal contamination can be tested as H2S is produced by bacteria in human and animal feces. The mediums used are peptone, dipotassium hydrogen phosphate, ferric ammonium citrate, sodium thiosulfate, teepol, and L-cysteine hydrochloride. The present study used commercially available test kits (LTek H2S test kits, LTek Systems, Nagpur, India). Water sample was filled up to the given mark, kept at ambient temperature (25°C –37°C) for 24–48 h, and color change was noted on follow-up. Water samples from the village overhead tank and five randomly selected wells (6 samples) were sent to microbiology laboratory of the institution for confirmation.
A total of ninety households were surveyed. [Table 1] describes the household characteristics of the survey. [Table 2] describes the WASH characteristics of the households. There were 61 (72%) households with drainage facilities, of which nine had open drainage. Five households shared a toilet facility. Government aid for building toilets was availed by 29 (34%) households. Well water was the main source of water supply in 27% of the households, and the rest had piped personal supply at home. Seventy-four (87%) houses had their water sources close to the source of contamination, i.e., <50 ft. Almost 45% did not treat water by filtering with cloth, boiling, or any other forms of treatment. Garbage was collected by Panchayat and 90% of the households availed this facility. Handwashing practice was most satisfactory (92.9%) after use of the toilet. All the wells were bricked or cemented, with two wells not having satisfactory cleanliness level around it. On inquiring about illness, 32% had some illness in the 6 weeks preceding the survey. There were 11 cases of diarrhea (12.9%), one case of worm infestation, and 15 (17.6%) cases of fever, although not all fever cases can be attributed to contaminated water.
|Table 2: Water, sanitation and hygiene characteristics of the surveyed households|
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On testing the water, 75 (88%) households had a positive test with color change suggestive of fecal contamination both at source and at point of consumption. Along with appropriate health education to each of the households, an information, education and communication session with Panchayat members was conducted. The six water samples subjected to testing in institution's NABL-accredited laboratory confirmed fecal contamination. The reports were communicated to the Panchayat and necessary action of disinfection of wells and overhead tank was advised.
The United Nations General Assembly states the right to clean water and sanitation as essential to realization of all human rights. As suggested by the NFHS-3, 43% of Indian households treat their drinking water, 19% strain it through cloth, 17% boil it, and 12% use some kind of filter. According to the Statistical Appraisal India Country Report, 2013 (country report), the rural coverage for access to improved water sources has increased from 61.0% to 90.4% from 1993 to 2008–2009. In the NFHS-3 report for Karnataka state, only 26% of the households have drinking water that is piped to their house/yard or plot. Water pollution in India is a grave problem, with almost 70% of surface water and large proportion of groundwater contaminated with biological or chemical pollutants. A recent systematic review found that inadequate hand hygiene affects nearly 80% of the world's population. It is important to note that due to poor handwashing practices, recontamination occurs even after boiling of water. Access to an “improved water source” provides a degree of sanitary protection, but it does not ensure that water is free of fecal contamination as pointed out by a recent systematic review and meta-analysis and we are likely to overestimate the access to safe water to communities. In the context of this information, the H2S strip test has the potential to empower the local governments. It can bring about a lasting change in the way local communities monitor their own drinking water. In terms of policy, it is important that it should be available at village level. It can be a “necessary” component rather than a “desirable” one in primary health care under IPHS. The visual nature, simplicity of use, and ability to perform at the field level with no advanced technical expertise required make it an important part of armamentarium of various point-of-care tests for public health in developing countries such as India.
The authors acknowledge the co-operation of the villagers and the Panchayat members. We also acknowledge the Indian Council of Medical Research (ICMR) for supporting this under the Short-Term Studentship (ICMR-STS).
Financial support and sponsorship
Financial support was provided in the form of Indian Council of Medical Research Short Term Studentship award of 10,000 rupees.
Conflicts of interest
There are no conflicts of interest.
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