Peter Kjær Mackie Jensen

Irrigation water as a source of drinking water: is safe use possible?

BACKGROUND In arid and semi‐arid countries there are often large areas where groundwater is brackish and where people have to obtain water from irrigation canals for all uses, including domestic ones. An alternative to drawing drinking water directly from irrigation canals or village water reservoirs is to use the water that has seeped from the irrigation canals and irrigated fields and that has formed a small layer of fresh water on top of the brackish groundwater. The objective of this study was to assess whether use of irrigation seepage water for drinking results in less diarrhoea than direct use of irrigation water and how irrigation water management would impact on health.

Is there an association between bacteriological drinking water quality and childhood diarrhoea in developing countries

To investigate the association between bacteriological drinking water quality and incidence of diarrhoea, we conducted a 1‐year prospective study in the southern Punjab, Pakistan. Diarrhoea episodes, drinking water sources and drinking water quality were monitored weekly among children younger than 5 years in 200 households. We found no association between the incidence of childhood diarrhoea and the number of Escherichia coli in the drinking water sources (the public domain). A possible trend was seen relating the number of E. coli in the household storage containers (the domestic domain) and diarrhoea incidence, but this did not reach statistical significance. Faecal contamination levels in household water containers were generally high even when the source water was of good quality. Under conditions such as this, it is questionable whether public water treatment will have a significant impact on the incidence of endemic childhood diarrhoea.

Hygiene versus fertiliser: the use of human excreta in agriculture--a Vietnamese example.

The use of human excreta as fertiliser in agriculture is a common practice in parts of South East Asia benefiting production but at the same time a risk factor for increased helminth infections. This paper describes the hygienic handling of human excreta for use in agriculture in Central Vietnam from a practical farming perspective presenting the farmers perceived health risks and benefits of its use. Further, in the study findings are discussed relating to the new Vietnamese guidelines for the use of human excreta in agriculture to their implications on an on-farm context. A total of 471 households in five communes responded to a structured questionnaire. This survey was supplemented by focus group discussions, key informant interviews and participant observations. More than 90% of the surveyed households used their own excreta as fertiliser and a total of 94% composted the excreta before use, either inside or outside the latrine. However, due to the prevailing design of the latrine and the three annual cropping seasons, it was found that for a minimum of one cultivation season per year 74% of the households will have only 3-4 months for composting before the input is needed in production, which is short of the 6 months stipulated in the national guidelines. The community associated great benefits from using human excreta in agriculture, especially if composted, and did not associate risks with the use of composted excreta if it was dry and lacked odour. It is recommended that the guidelines be revised and attempts made to identify ways of reducing the time needed to ensure the die-off of helminth eggs, including the use of pH regulators, such as an increased use of lime in the latrines.

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

BackgroundFor 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.MethodsBy 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%.ResultsRegardless 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.ConclusionBy 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.

Successful sanitation promotion must recognize the use of latrine wastes in agriculture: the example of Viet Nam

To achieve the aims of the Millennium Development Goals, significant investments will be required to increase sanitation coverage and improve the management of human excreta. The United Nations Millennium Task Force on Water and Sanita-tion put forward 10 crucial actions that would be needed, and among these is a pledge for governments to support sanitation solutions that are technically, socially, environmentally and financially appropriate (1).In eastern Asia one of the key aspects to be considered when promoting appropriate sanitation solutions and design-ing health education programmes is the use of human excreta as an agricultural fertilizer. The centuries old tradition of using human excreta on farmland has been abandoned in Europe, but is still widespread in east Asia, especially in China and Viet Nam. Although there may be negative health consequences of the use of excreta as fertilizer, it is argued here, in reference to the current situation in Viet Nam, that if this is a com-mon practice among farmers, then sanitation programmes and hygiene campaigns must acknowledge its existence and design systems that allow for excreta to be used in the safest way possible.

Limitations of Irrigation Water Quality Guidelines from a Multiple Use Perspective

The standards for irrigation water qualityare currently provided by global andnational guidelines that are mostly basedon the assumption that threshold valuescould be applied to protect crops. Thisapproach can create problems for a largelyunrecognized group of people who make useof irrigation water for non-agriculturalpurposes. At the same time, increasingwater scarcity will lead to the need forrecycling of water in irrigated riverbasins, and the use of low qualityirrigation water. Apart from hazards ofhigh pollutant levels, a sustainabilitycriterion has to be included in the waterquality guidelines to account for long-termlow-level application of certain pollutantsthat can accumulate in the environment.Using the example of cadmium, it is arguedthat the current guidelines need to berevised and should take local factors andfuture developments into account.

Specificity for field enumeration of Escherichia coli in tropical surface waters

In remote rural areas in developing countries, bacteriological monitoring often depends on the use of commercial field media. This paper evaluates a commercial field medium used for the enumeration of Escherichia coli in different surface waters under primitive field conditions in rural Pakistan. In order to verify the field kit, 117 presumptive E. coli isolates have been tested, finding a specificity of only 40%. By excluding some strains based on colony colours, the calculated specificity could be increased to 65%. Thus, it is suggested that prior to use in a tropical environment, the specificity of any commercial medium used should be tested with representative tropical isolates, in order to increase the specificity.

Drinking cholera: salinity levels and palatability of drinking water in coastal Bangladesh.

To measure the salinity levels of common water sources in coastal Bangladesh and explore perceptions of water palatability among the local population to investigate the plausibility of linking cholera outbreaks in Bangladesh with ingestion of saline‐rich cholera‐infected river water.

Cholera Epidemics of the Past Offer New Insights Into an Old Enemy

We investigate cholera transmission using data from historical cholera epidemics. The results suggest short-cycle (household/institution level) transmission was important in early secondary transmission. This study of historical outbreaks can inform investigations in current cholera epidemic settings.

Can E. coli fly? The role of flies as transmitters of Escherichia coli to food in an urban slum in Bangladesh

To investigate the transmission of faecal bacteria by flies to food under natural settings.