Assessing factors of E. coli contamination of household drinking water in suburban and rural Laos and Thailand

Drinking water (DW) can serve as a route for disease transmission if not properly managed. The study assessed the effect of different factors on Escherichia coli quantities in DW in householdwater storage containers in suburban and rural villages in Laos and Thailand. Higher E. coli concentrations in DW were found in Laos compared to Thailand, especially in householdswithout toilets (in Laos) and in rural rather than in suburban villages. In suburban Laos, housematerial, storage container types and lack of toilets were significantly associated with E. coli contamination of DW, whereas in rural Laos, corresponding significant factors were rain-fed water, containers with lids and lack of toilets. In suburban Thailand, rain-fed water, storage container types and container cleaning frequency were significantly associated with DW contamination, while house materials, manually collected rainwater and container cleaning frequency were associated with contamination in rural Thailand. Sociodemographic characteristics were less associated with E. coli contamination of DW in this study. Treatment of household stored water (e.g. boiling), regular cleaning of rain jars as well as the provision of household toilets, especially in Laos, can provide barriers against E. coli contamination of DW. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/). doi: 10.2166/ws.2017.133 om https://iwaponline.com/ws/article-pdf/18/3/886/208076/ws018030886.pdf 2020 N. Vannavong (corresponding author) H. J. Overgaard N. Dada Faculty of Science and Technology, Norwegian University of Life Sciences, Ås N-1432, Norway E-mail: anandafet@gmail.com N. Vannavong Champasak Provincial Health Office, Pakse, Lao PDR T. Chareonviriyaphap Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand R. Rangsin Department of Military and Community Medicine, Phramongkutklao College of Medicine, Bangkok, Thailand A. Sibounhom Department of Communicable Disease Control, Ministry of Health, Vientiane, Lao PDR T. A. Stenström SARChl Chair, Institute for Water and Waste Water Technology, Durban University of Technology, Durban, South Africa R. Seidu Water and Environmental Engineering Group, Institute for Marine Operations and Civil Engineering, Norwegian University of Science and Technology, Ålesund, Norway


INTRODUCTION
Over the last decade, the diarrhoeal mortality among children under five has decreased globally from 1.2 million (in 2000) to 760,000 (in 2011), but 90% of these child deaths are still linked to water, sanitation and hygiene (UNICEF ). In Southeast Asia, 363,904 diarrhoeal deaths of all ages were estimated to be linked with inadequate water, sanitation and hygiene, which constitute 56% of diarrhoeal diseases in this region (Prüss-Ustün et al. ).
Storage of drinking water (DW) is a common practice in many countries where access to DW is either not available within the home environment or, if available, flows intermittently. DW can serve as a source of diarrhoeal disease transmission if not properly managed (WHO ). Among the causes of diarrhoeal disease incidence, the storage of DW within the household environment remains a significant risk factor (Roberts et al. ; Günther & Schipper ). All pathogens of viral, bacterial, parasitic and protozoan origins, implicated in gastroenteric disease outbreaks, may be found in the source water if contaminated, or introduced into the stored water due to poor handling.
In Laos and Thailand, many households have access to tap water, but prefer rainwater because the taste is considered better (Pinfold et al. ). Rainwater is collected during the wet season and stored throughout the year.

). A review on household DW in developing countries
showed that stored water is often of a worse microbial quality than water from the source (Wright et al. ). Storage even for a short time can lead to microbial contamination of good-quality DW due to unhygienic handling. The stored DW in both Laos and Thailand was previously shown to partly be affected by microbial contamination with Escherichia coli (E. coli) (Dada et al. ) and did not comply with the World Health Organization (WHO) guideline of zero E. coli/100 mL (WHO ). A study conducted in Cambodia found a significant relationship between diarrhoeal disease and E. coli levels of 11 CFU/100 mL in DW compared with a reference E. coli level of <1 CFU/100 mL (Brown et al. ). Similar findings were made in rural households in South Africa and Zimbabwe where diarrhoeal disease was associated with E. coli levels of 10 CFU/100 mL in household DW collected from a communal source (Gundry et al. ). Other studies have found significant relationships between diarrhoeal disease incidence and the presence of E. coli in household DW (Jensen et al. ; Levy et al. ).

Study areas
This study was conducted from February to April 2011 in Manchakhiri district, Khon Kaen province in northeastern Thailand, and from May to June 2011 in Lakhonpheng district, Salavan province in southern Laos ( Figure 1). Using existing health data and in consultation with each country's public health departments, one suburban and one rural village per country were selected based on previously described criteria (Dada et al. ).

Study design and data collection
The study was a cross-sectional survey involving household interviews, observations and water sampling. A systematic random sampling procedure was used in the selection of study households from a total of 215 and 130 households in the suburban and rural villages in Laos, and from a total of 272 and 139 households in the suburban and rural villages in Thailand, respectively. This resulted in the inclusion of 121 and 114 households from suburban and rural Laos, and 117 and 121 households from suburban and rural Thailand, respectively. General characteristics of the households were obtained through interviews using semi-structured questionnaires administered to household heads. Information collected included socio-demographic characteristics (Tables 1 and 2), DW sources (e.g. rain-fed water (rainwater that is collected directly from the rooftop, through the roof-connected tube or from a metal roofing sheet), manually collected rainwater (rainwater that is collected manually from large containers), purchased bottled water, and borehole water), water management practices, sanitation facilities and hygiene. This was further supplemented by observations to ascertain the types of toilet facilities that were in use, presence of soap at handwashing facility, types of water storage containers, presence or absence of a secured lid on the water storage containers and mode of collecting water to drink. The interviews and observational surveys were conducted together with trained field staff (village health volunteers). The DW samples were collected from a total of 139 and 145 water containers in suburban and rural Laos. In Thailand, 178 and 268 DW samples were collected from the suburban and rural villages, respectively. Samples were collected using sterile 100 mL Whirl-Pak bags, put on ice and transported to a field laboratory where they were analyzed for E. coli within 24 h after sampling. E. coli analysis was done using Colisure-Quantitray/2000 method (Colisure ® WCLS2001, IDEXX Laboratories, Inc., Westbrook, ME, USA). Details of the E. coli analysis and identification procedures are described in Dada et al. (). E. coli results were expressed as most probable number (MPN)/100 mL.
E. coli was chosen as a faecal indicator in this study because it is easy and less costly to analyze; and is identified as the most suitable indicator of faecal contamination in DW. Also, it is generally considered as a reliable indicator for the presence or absence of other pathogenic bacteria such as Salmonella, Shigella and Campylobacter spp.
(WHO ). Although thermotolerant coliforms are also recommended and used as alternative group of faecal indicator organisms, a review showed that E. coli, rather than thermotolerant coliforms, in household DW was significantly associated with diarrhoea (Gruber et al. ).

Data analysis
Descriptive analysis was undertaken to examine the statistical distribution (frequency, percentage, central tendency and rate) of factors related to socio-demographic characteristics, DW, water management, sanitation and hygiene. The mean, minimum and maximum of E. coli (MPN/100 mL) concentration related to all study factors were displayed.
Households were ranked into rich, intermediate and poor ones using principal components analysis and based on group weighted mean scores (Vyas & Kumaranayake ).
The variables used in the wealth status ranking are presented in Table 1. A univariate analysis was undertaken to assess the independent effect of these factors on the occurrence of

Socio-demographic characteristics of households
The socio-demographic characteristics of the study households are presented in Table 2. Over 90% of the household members in both countries were literate and the main occupation was agriculture, especially in the rural villages in both countries (over 94%). Households in Thailand were wealthier than in Laos. In Thailand, most houses were made of cement-wood (70% in suburban and 61% in rural village); while in Laos, the houses were mainly made of wood alone (42% in suburban and 85% in rural village).
DW sources, management practices and levels of E. coli contamination The main source of DW in both suburban Thailand and Laos was purchased bottled water (Combined Table 3a and 3b)  (Table 3a).
Although the majority of the containers in all villages had lids (80-98%) they were unprotected from contamination, especially in both rural villages. The concentration of E. coli was high in stored DW in households that collected water by scooping compared to those that poured Percentages in parentheses. a Retired, unemployed and student.  from containers to drink, except in rural Thailand (Table 3b).
Nearly all containers in Laos (98%) were reported to be cleaned at least biweekly. In Thailand, however, containers were cleaned less frequently; 30% of suburban containers and 50% of rural containers were cleaned monthly or less frequently (Table 3b).

Types of DW containers
Bottles were the most commonly used DW containers in suburban Laos, followed by buckets, while in the rural village jars and buckets were used equally (Table 3a). In Thailand, generally, jars and buckets were the most commonly used DW containers, with jars being the most predominant in the rural village (Table 3b). Jugs and containers grouped as 'other' were more common in Laos than in Thailand, but were the least used across all sites (  (Table 3a).

Sanitation and hygiene
In Laos, 77.2% of the households in rural villages had no toilet facilities compared with 30.6% in suburban villages.
In Thailand, nearly all households (100% in suburban and 98.3% in rural village) had toilet facilities (    (Table 3a).

Multivariate analysis
As with the univariate analysis, results from the multivariate analysis revealed that the main factors contributing to the occurrence of E. coli in stored DW at the household level was country specific and varied from location to location (Table 5).
Rain-fed water in rural Laos and suburban Thailand, and manual filling of containers with rainwater in rural Thailand were significantly associated with the occurrence of E. coli in DW containers (Table 5)   This study revealed that access to improved toilet facilities could provide a significant barrier against the contamination of stored DW within the household environment. Lack of access to toilet facilities was significantly associated with E. coli contamination of DW. This was particularly evident in Laos where a significant proportion of households in suburban and rural villages were without toilet facilities (Table 2).

DW in households without toilets in suburban and rural
Laos had high levels of E. coli contamination (Table 3a)

CONCLUSIONS
We conclude that the concentration of E. coli in stored DW in the household environment is higher in Laos than in Thailand, especially in households without toilets in both villages in Laos, as well as in the rural rather than suburban villages of both countries. Different factors contribute to the deterioration of water quality, and these vary across villages.
From the final analysis, the factors that were significantly associated with the occurrence of E. coli in DW in suburban Laos were wooden house material, jars and bottles, and households without toilets; whereas, in rural Laos, the factors were rain-fed water, containers covered with lids and households without toilets. In suburban Thailand, significant factors associated with the occurrence of E. coli in DW were rain-fed containers, jars, buckets and container cleaning frequency; whereas, in rural Thailand, they were wooden house material, manually collected rainwater and container cleaning frequency. This study revealed that socio-demographic characteristics were less associated with E. coli contamination in DW, compared to sanitation and hygiene. This may not always be the case in every setting, as all of these factors (Table 5) generally have been associated with E. coli, hence, each or any combination of these factors serve as potential risk factors for faecal contamination. The levels of E. coli contamination found in all study sites were above the WHO drinking-water quality guidelines. Health education for appropriate treatment of stored DW (e.g. boiling) prior to drinking can provide a significant barrier against diarrhoeal disease incidence in households with poor water quality. In Laos, interventions related to the provision of improved toilet facilities have the potential of improving the quality of stored DW.