Water System Publications
prevention in Bolivia through point-of-use disinfection and safe storage: a promising
Quick R, Venczel L, Mintz
E, Soleto L, Aparicio J, Gironaz M, Hutwagner L, Greene K, Bopp C, Maloney K,
Chavez D, Sobsey M, Tauxe R
novel water quality intervention that consists of point-of-use water disinfection,
safe storage and community education was field tested in Bolivia. A total of 127
households in two periurban communities were randomized into intervention and
control groups, surveyed and the intervention was distributed. Monthly water quality
testing and weekly diarrhoea surveillance were conducted. Over a 5-month period,
intervention households had 44% fewer diarrhoea episodes than control households
(P =0.002). Infants < 1 year old (P = 0.05) and children 5-14
years old (P = 0.01) in intervention households had significantly less
diarrhoea than control children. Campylobacter was less commonly isolated
from intervention than control patients (P = 0.02). Stored water
in intervention house holds was less contaminated with Escherichia coli
than stored water in control households (P < 0.0001). Intervention households
exhibited less E. coli contamination of stored water and less diarrhoea
than control households. This promising new strategy may have broad applicability
for waterborne disease prevention.
which are frequently transmitted by faecally-contaminated water, continue to be
a leading cause of morbidity and mortality among children in developing countries
[1,2]. The optimal approach to preventing waterborne diseases, which includes
the construction of water disinfection and delivery systems and sewage treatment
facilities, is very expensive and time consuming .
for Disease Control and Prevention (CDC) and the Pan American Health Organization
(PAHO) have developed an inexpensive, rapidly implementable alternative for water
quality improvement . This intervention consists of three elements:
(1) point-of-use treatment
of contaminated source water with disinfectant produced locally using appropriate
technology; (2) safe storage of treated water; (3) community education. In a pilot
trial, an Aymara Indian community in El Alto, Bolivia, used this intervention
on water from contaminated surface sources to produce drinking water that met
World Health Organization guidelines for microbiologic water
quality . To determine the efficacy of this intervention in preventing diarrhoeal
diseases, we conducted an intervention trial in two periurban communities of Montero,
Bolivia, a city located in the subtropical eastern lowlands.
households of the two study communities were invited to participate in the study.
In July 1994, we interviewed the person responsible for handling water in the
household, usually the female head of household or oldest daughter, about family
socioeconomic and demographic characteristics, hygienic habits and water handling
August 1994. we collected baseline water samples from household wells and drinking
water storage containers and observed sanitary conditions of the household and
surrounding yard. We determined free and total chlorine levels using the N,N-diethylphenelyenediamine
colorimetric method (Hach Co., Loveland. CO). Water samples were tested for Escherichia
coli contamination with the membrane filtration technique , using selective
m-TEC agar (Difco Laboratories. Detroit, MI).
the study, water disinfectant was produced by a local community health worker
using a MIOX unit (LATA. Inc., Los Alamos. NM). From a 3% brine solution, the
MIOX unit electrolytically produces disinfectant with hypochlorite, chlorine dioxide,
ozone, peroxide and other oxidants. The disinfectant was packaged in 500-ml reusable
containers with caps that were used to measure and dispense disinfectant into
household water storage, 20-litre polyethylene water vessels (referred to hereafter
as the special vessel) with a narrow mouth, a spigot and a comfortable handle
were used (Toico, Inc., Toledo. OH). Labels illustrating appropriate use of the
vessels and disinfectant were affixed to the vessels. The labels also illustrated
suggested applications of treated water, which included drinking, handwashing,
cleaning utensils and washing produce. Visiting community health volunteers were
already promoting all of these suggested hygienic measures, including the importance
of water treatment, on a regular basis to all households, including controls,
in both study communities.
were randomized by a simple public lottery into two groups; one to receive the
inter vention. the other to serve as a control group. From 22 to 25 August 1994,
community health volunteers distributed one container of disinfectant and two
special vessels to each intervention household and explained how to treat and
store water with these products. Once a week. community health volunteers distributed
containers with freshly prepared disinfectant to each intervention household,
removed old containers, and used the labels on the special vessels to reinforce
messages about proper use of the disinfectant and vessels and remind participants
of different applications for treated water.
visits at monthly intervals were made to all participating households from September
1994 to February 1995 to survey water-handling practices and to test stored and
source water quality as described above.
1 October 1994 to 28 February 1995, a specially-trained health worker made weekly
visits to all households to obtain information about all household cases of diarrhoea,
defined as equal to or greater than 3 loose or watery stools in 24h, with onset
in the preceding 7 days. At each visit, the health worker attempted to obtain
from every person with diarrhoea two rectal swabs that were placed in Cary-Blair
media for transport to a local laboratory for bacterial culturing, and a stool
sample in a plastic container for microscopic analysis and enzyme-linked immuno-sorbent
assay (ELISA) testing for rotavirus (Cambridge Biotech, Boston. MA). Swabs were
tested for salmonella, shigella, Campylobacter, and Vibrio
cholerae using standard techniques. Five lactose-positive and two lactose-negative
colonies were selected from MacConkey agar plates and sent to CDC to test for
enteroioxigenic E. coli (ETEC) using previously described techniques .
Fresh stool specimens were examined microscopically for parasites.
Info, Version 6.02 (USD, Inc., Stone Mountain, GA) software was used for descriptive
and univariate data analysis. The Kruskal-Wallis test was used to analyse data
that were not normally distributed. SAS software (SAS Institute, Gary, NC) was
used for univariate and multivariatc analyses of data on microbiologic water quality
and diarrhoea. Generalized estimating equations were used to analyse repeated
observations of diarrhoea episodes in individuals over time in intervention and
control groups, controlling for clustering within households .
study protocol was approved by the CDC Institutional Review Board and informed
consent was obtained from all subjects or their guardians.
A total of 127 households
with 791 persons participated in the study (mean, 6.2 persons per household),
representing 91 % of households in the study area. The median age of the study
population was 14 years (range, 1 month-83 years): women made up 51.6%.
Of 362 persons over age 14 years for whom there were data, 50 (14 %) were illiterate
and 182 (50 %) reported having < 6 years of schooling. Mean per capita annual
income was S230. Twelve households from the two communities were excluded from
the study: 10 families moved during the study and two refused to participate.
There were no statistically significant demographic differences between excluded
and participant households.
(<5m deep), uncovered household wells were the primary drinking water source
for 111 (87%) of 127 households. A covered, 50-m-deep well with a handpump was
the source for 14 (11 %) households: 2(16
%) households used water from a household tap in a neighbouring community. Water
was stored in 98 households (77%); it was fetched for immediate use as needed
for the other 29. Of 98 households storing water, 94 (96%) used wide-mouth containers,
which would permit hand contact with stored water: in 64 (68%) of 94 homes where
direct observations were made. at least one water storage container was uncovered.
Respondents from 48 (51 %) of these 94 households acknowledged that hands sometimes
touched the stored water while water was being obtained from the container.
Only 48 (38%)
of 127 respondents reported ever treating their drinking water: 16 (33%) boiled
it, 15 (31%) added bleach, 11 (23%) did both, 4 (8-3%) filtered it through a cloth,
and 2 (4%) added lemon juice. During baseline water sampling, 80 (63%) of 127
households had stored water, but only 17 (21 %) of these 80 respondents claimed
it had been treated. No stored water samples had detectable chlorine. The median
E. coli colony count was 57050/100 ml (range, 1-8000000) for well
water samples, and 46950/100 ml (range, 1-8000000) for samples of stored water.
of 126 respondents claimed always to wash their hands after defecation, while
28 (22%) individuals
reported engaging in this practice almost always or sometimes: handwashing before
food preparation was reported to be performed always by 96 (76%) of these respondents
and almost always or sometimes by 30 (24%) individuals. Handwashing before eating
was reported to be practised always by 88 (70%) respondents, almost always or
sometimes by 36 (29%) individuals, and never by only 2 (2%) respondents. Raw fruits
and vegetables were claimed to be washed always by 82 (65 %) respondents, almost
always or sometimes by 41 (33 %) persons, and never by 3 (2%) respondents. Of
126 respondents, 101 (80%) claimed to wash cooking and eating utensils always,
while24 (19%) indicated almost always or sometimes, and only 1 (1 %) never washed
(55%) of 127 households had a latrine that was in good or fair condition, but
only 60 (47%) respondents reported using it: the remainder disposed of human waste
on the open ground or in a hole in the ground. One hundred and twelve (88%) households
possessed animals, including dogs (77%), chickens (71%), and ducks (67%). Human
or animal faeces were observed in the yard surrounding 97 (76%) of 127 households.
intervention group consisted of 64 households with 400 individuals (mean, 6-3
persons per household: range, 2-13). The control group had 63 household with 391
individuals (mean. 6-2 persons per household: range. 1-16). There were no statistically
significant differences between intervention and control households in demographic
characteristics, sanitary conditions, water handling practices, hygienic practices,
or baseline E. coli colony counts in either well or stored water.
During the first
month of the intervention phase, investigators observed stored water in special
vessels in 92% of intervention households: over the subsequent 6 months, this
proportion declined to 69% (Table 1). The most common reason cited for not having
water in the special vessel at the time of the monthly-visit was that the vessels
had not yet been filled that day. Over the course of the study, the proportion
of households that reported using the special vessel declined from 100 to 98%.
The proportion of stored water samples with detectable levels of total chlorine
increased from 71 % at the time of the first observation to 95% at the final visit
1. Percent of households with water observed in storage vessels and chlorine
detected in stored water during monthly-field visits. Montero. Bolivia, July 1994-February
of intervention households with water in
special vessels ||%
of intervention households with detectable
total chlorine in
intervention households with water in special vessel and chlorine
in vessel water||%
of intervention households with detectable total chlorine
in usual water storage
each of the six sampling rounds, stored water samples from intervention households
had significantly lower median E. coli colony counts than samples
from control households (P < 0.0001) (Table 2).
The proportion of water samples from special vessels that had no detectable E.
coli colonies ranged from a low of 56% in the first sampling round to a
high of 79% in the fourth round (Table 2).
2. Median Escherichia coli colony counts per 100 ml in water
stored in special vessels in intervention households and water stored in usual
vessels in control households, and percent of water samples with no delectable
E. coli colonies. Montero. Bolivia. July 1994-February 1995
households||Control households|| |
E. coli colony count per
100 ml (range)
of household samples
with no E.
coli count per 100 ml (range)
of household samples
with no E.
for comparison of
median E. coli colony counts between
diarrhoea episodes and mean episodes per person in intervention and control groups.
Montero. Bolivia. October 1994-February 1995
value for comparison
episodes between groups
4. Univariate analysis by GEE* of risk factors for diarrhoea among individuals
living in intervention and control households. Montero. Bolivia. October 1994-February
Annual per capital income
of stools in yard
Touch water with hand
Animals allowed in house
Over a 5-month period,
the active surveillance system detected 231 cases of diarrhoea: 83 in intervention
households versus 148 in control households (Table 3). This represented an overall
reduction in diarrhoea incidence over the 5-month period of 44 %, from 0.38
episodes per person to 0.21 per person (P = 0.002). The mean
number of reported diarrhoea cases per household was 1.30 for intervention
families and 2.35 for control families (P = 0-02).
all age-groups, intervention household members had fewer reported episodes of
diarrhoea than did members of control households (Table 3). The protective effect
was strongest for infants, among whom the reduction in incidence was 53 % (P =
0.02), and for children 5-14 years old. among whom the reduction was 59%
(P = 0.01). Reductions in the mean number of diarrhoea episodes for persons
in the age-groups 1-4 years and > 15 years did not reach statistical significance.
analysis of potential risk factors for diarrhoea among individuals revealed that
diarrhoea risk was less for older persons, and for individuals who belonged to
intervention households (Table 4). Diarrhoea risk was greater for males. Diarrhoea
risk tended to be less for individuals living in households with a latrine in
active use, but this result did not reach statistical significance. We
constructed a model that included the statistically significant and borderline
significant risk factors from the univariate analysis. Multivariate GEE analysis
of this model showed that belonging to an intervention household (OR 0-64, P =
0.02) and older age (OR 0.95, P < 0.001) were independently
having fewer episodes of diarrhoea. Male sex (OR 1.51, P = 0.02)
was independently associated with an increased risk for diarrhoea. Living in a
household with no visible faeces in the yard (OR 0.73, P = 0.14)
tended toward an association with a lower risk for diarrhoea, but this result
was not statistically significant. Interactions were tested between the independently-associated
variables and none was found to be significant.
swabs were obtained from 36 (43%) of 83 diarrhoea patients in 22 household in
the intervention group and from 60 (41%) of 148 patients in 28 control households.
A bacterial pathogen was isolated from 27 (28 %) of the 96 swabs. Campylobacter
was isolated from 20 (20%) swabs: 2 (6%) from intervention cases and 18 (30%)
from control cases: all were < 5 years old. Because diarrhoea episodes within
households are not independent of each other, we restricted univariate analysis
of Campylobacter cases to the household, rather than to the individual
level. Campylobacter was isolated from stool specimens from 2 (9%) of 22
intervention households and 12 (43%) of 28 control households (OR 0.2,
95% confidence interval 0.03-0.8). Stool specimens from 8 households
yielded ETEC, 5 of which were obtained from patients in intervention households
(P = 0.28). Only one (1%) stool specimen yielded salmonella
and one (1%) yielded shigella; both were from control group patients.
ELISA tests for
rotavirus were conducted on 65 (68%) of 96 specimens; 4 (6-2 %) were positive,
three of these from intervention group patients. Of 91 stool samples examined
microscopically, Ascaris lumbricoides was identified in 38 (42%). Giardia
lamblia in 21 (23%). Enmrnoeba histolytka in 1 (1%). and other parasites
in 25 (27%). Thirty-three (35%) specimens were negative and 27 (30%) samples had
multiple parasite species. There was no significant difference in the number of
enteric parasitic infections in intervention and control group patients.
Households using a
simple water storage and treatment intervention experienced substantially less
diarrhoea during the summer diarrhoeal season in Bolivia than did households using
traditional water-handling and storage practices. Participant households achieved
this result despite living in a high-risk environment where drinking water sources
were heavily contaminated with E. coli where only 53 % of households had
access to a latrine, and where human and animal faeces were present on the ground
around most homes. The intervention - an inexpensive combination of point-of-use
water treatment, safe water storage vessels, and hygiene education - was readily
adopted and applied.
willingness of a population to adopt a novel health practice is an important determinant
of an intervention's long term success. This study population demonstrated their
acceptance of the intervention through consistently high compliance by several
measures - reported use of the special vessel (98%), observed use of the special
vessel (range 69-92 %), observed use of disinfectant in special vessel water samples
(range 7&-95%), and observed concurrent use of the special vessels and disinfectant
(57-69%) [Table 1]. The observed use of the special vessel declined from 92 to
69% during the course of the study. Although most respondents whose vessels were
empty at the time of follow-up visits claimed that they had not yet filled their
vessel that day, the decline in observed use could be indicative of a return to
old habits and points to the importance of ongoing efforts to motivate a population
to sustain changes in health behaviours. The best functional indicator of compliance
in this study was observed concurrent use of the vessel and disinfectant, which
remained remarkably consistent throughout the study.
44% reduction in diarrhoeal disease episodes in intervention families was higher
than that reported for most water quality interventions [9, 10], Most previous
studies evaluated capital-, time-, and labour-intensive piped-water or well projects
that did not include
chemical disinfection and safe water storage in the home, nor community education.
In contrast, this intervention coupled initial water disinfection with barriers
to recontamination. The first barrier was the water storage vessel itself. Clean
water stored in the open buckets or barrels typically used in developing countries
becomes contaminated [11,12]. Not surprisingly, water stored in narrow-mouth or
covered water vessels is less likely to become contaminated [13-16]. The presence
of residual hypochlorite in treated water provided a second barrier to recontamination
[17,18]. Hygiene education was also an important component of the intervention.
Alone, it can lead to a reduction in the incidence of diarrhoeal diseases in children
(19,20], and this effect is multiplied when families are also given a safe storage
observation of greatest benefit in two age-groups, infants < 1 year old and
children 5-14 years old, may be due to behavioural characteristics of each group.
Most infants are under the continual care of their mothers or older siblings,
who control their drinking water source. Children 5-14 years old can be taught
what to eat or drink and what to avoid, so the possibility of compliance with
the intervention is improved. The lack of protective effect among children 1-4
years of age may reflect their ability to walk and explore their surroundings,
and their inability to avoid exposure to potential pathogens in a faeces-laden
environment. Because this age-group is most susceptible to diarrhoea morbidity
and mortality, the ultimate impact of this intervention on mortality may be limited,
although there is evidence that improved water storage protects against persistent
diarrhoea , which has a much higher case fatality rate than acute diarrhoea.
Reducing diarrhoea, and the consequent risk of mortality, in this age-group may
require additional interventions that focus on reducing faecal contamination of
the household environment.
intervention was not the only factor associated with diarrhoeal incidence. In
the umvanate analysis, the presence of a functional latrine tended toward being,
protective, and in the multivariate analysis, the absence of observable faeces
in the immediate household environment tended toward an independently protective
effect. Although the intervention did not include a human waste disposal component,
these findings, though not statistically significant, suggest the importance of
waste disposal to diarrhoea prevention efforts and support the well-documented effectiveness
of excreta disposal interventions for diarrhoea prevention [9, 10].
and ETEC were the only enteric bacterial pathogens detected frequently in this
study. The high frequency of Campylobacter isolation may reflect the high
percentage of families that possessed animals, particularly poultry, and that
had inadequate environmental sanitation. Other studies of impoverished communities
in Latin America have detected high rates of infection with Campylobacter
. The intervention specifically decreased Campylobacter infection rates,
a plausible finding because water is a recognized vehicle of transmission of this
microorganism [23-25]. ETEC was the second most commonly isolated bacterial pathogen.
Although the numbers are small, the lack of an apparent protective effect for
ETEC infections suggests that, in this population, water may not be the predominant
mode of ETEC transmission. The rarity of positive rota virus ELISAs may reflect
the seasonality of the infection. The study encompassed only the rainy summer
season, while rotavirus may be more commonly isolated during drier winter months
intervention is a promising way of providing microbiologically safe water in developing
countries. While supplying piped, treated water to all households remains elusive
for many communities, this point-of-use disinfection and safe water storage intervention
can be rapidly disseminated, is inexpensive, simple to use, and adaptable to a
variety of conditions. A similar water vessel can be manufactured in Bolivia at
a cost of under US $4.00 each. The disinfectant can be produced in any community
by inexpensive, solar-powered electrolysis of a salt water solution for as little
as $0.05 per family per year . An earlier cost-effectiveness study estimated
that this intervention would have no net cost to society if it decreased diarrhoea
incidence by 20% or more . Ultimately, the utility of this intervention will
be determined by its acceptability and sustainability in diverse populations.
Social marketing will be an important component of efforts to enhance the intervention's
acceptability and to ensure its sustainability through commercialization. An attractive
aspect of this intervention is that it yields a product, the disinfectant, which
can be marketed beyond the community as an alternative to boiling, which is expensive
and time-consuming, and to solar disinfection, which is time-consuming and does
not prevent recontamination. However, to ensure success, formative
research will be necessary to assess the need and demand for such an intervention
in a given
population, and provision must be made to produce all elements of the intervention
in the implementing country. Start-up costs for the production of the special
vessels, disinfectant, and promotional materials, and for the establishment of
distribution networks, will be substantial. The prospect of local management of
the project and either full or partial cost recovery enhances the potential for
success. Further 'real life' investigations of this and similar strategies in
other communities and at a larger implementation scale will define better the
potential of this promising new strategy for waterborne disease prevention.
study was funded by a grant from the Pan American Health Organization. We would
like to acknowledge substantial logistical and administrative support provided
by the Villa Cochabamba Health Center, the Child and Community Health Project
and Andean Rural Health Care. We would like to recognize the invaluable collaboration
of Juan Carlos Guarabia, Carmen Revollo, Patricia Machaca, Faustino Trujillo,
Mihail Soliz, the community volunteers, Rosa Munoz, Silvia Luz Pantoja, Maria
Esther Claros, Teresa Ruiz, Dr Minha Roses, Guitlermo Orozco, Carlos Espana, Kristina
Gardell, Dr Martha Mejia, Carmen Salinas and Ana Revilla. We are deeply indebted
to the people of Villa Virginia and Barrio Pampa de la Madre for collaborating
so graciously with us and for their good-natured tolerance of the many interruptions
we made in their daily lives.
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