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Safe
Water System Abstracts
A
new strategy for waterborne disease transmission
Quick R, et al. In
many parts of the developing world, drinking water is collected from unsafe sources
and is further contaminated during storage in household vessels. We have developed
a simple, inexpensive system for point-of-use disinfection and storage of water
which has 3 elements: for disinfection, a sodium hypochlorite solution produced
from water and salt using appropriate technology; for safe storage, a 20-litre
plastic vessel with a narrow mouth, lid, and spigot (referred to hereafter as
the special vessel); and community education to ensure proper use of this system
and to teach populations about the association between contaminated water and
disease (Mintz, 1995). A field test of this system in El Alto, Bolivia demonstrated
a high level of acceptance among impoverished Aymara Indian families (Quick, 1996).
Stored water in households that used the system had lower levels of contamination
with E. coli than water in households that used their traditional storage systems.
A second field test among vendors in the markets of Guatemala City, Guatemala,
showed that there were lower levels of contamination with fecal coliform bacteria
in samples of stored water and beverages from vendors using this system than from
vendors not using this system (Sobel, 1997). Two field trials have been conducted
in the past 3 years to test the effectiveness of this system in preventing diarrhea
and its sustainability on 3 large scale.
Field Trial I
Objectives
To evaluate the effectiveness of this water treatment and
storage system in improving water quality and preventing
diarrhea.
Methods
Baseline surveys of demographic characreristics, water
handling practices, and water quality were conducted in households in 2 periurban
communities in Montero, Bolivia. Households were then randomized into intervention
and control groups; the intervention group received the water treatment and storage
system and education about its use. Fresh disinfectant was provided weekly. Monthly
water quality surveys and weekly active surveillance for diarrhea were conducted
from September 1994 through February 1995.
Results
A total of 127 families with 790 members participated in
the study, 64 in the intervention group and 63 in the control group. The baseline
median E. coli colony count for water stored in study households was 46,950/100
ml. Following distribution of the water treatment and storage system, stored water
samples from intervention households had significantly lower median E. coli
colony counts than stored water from control households in all 6 monthly sampling
surveys (p<0.0001). Among intervention households, the percent of water samples
with no detectable E. coli colonies ranged from 56 per cent to 79 per cent
in the 6 water quality surveys. During 5 months of diarrhea surveillance, intervention
households had 83 cases of diarrhea, and control households 148 cases. The mean
number of diarrhea cases per household was 1.30 for intervention families and
2.35 for control families, a difference that was statistically significant (<0.05)
.The effect was strongest in two age groups, infants <1 year old and children
5 to 14 years old, from intervention households who had significantly fewer episodes
of diarrhea per person than their counterparts from control households (p<0.05).
Multivariate analysis showed that belonging to an intervention household (p<0.05
), having a functioning latrine (p<0.05 ), and having no visible faeces in
the yard (p<0.05) were all independently associated with having fewer episodes
of diarrhea in a family.
Field Trial II
Objectives
To test if this water treatment and storage system is sustainable
and evaluate its effectiveness in preventing diarrhea under "real world"
conditions.
Background
A social marketing campaign was designed in Bolivia to make
the system sustainable by creating microenterprises to produce and sell the special
water vessel and disinfectant solution, by promoting the products, and by educating
the population in their use. The intervention was given a logo and a brand name,
CLARO, which is Spanish for "clear" and "of course." A video-tape,
pamphlets, and flip charts were produced to teach about the association between
water and diarrhea and to demonstrate how CLARO could be used to prevent diarrhea.
Promotional CLARO T -shirts and baseball caps were made to give to health personnel,
public figures, and consumers. A rally with local and national leaders and the
general public, with extensive media coverage, was held to launch the product.
A radio and television advertising campaign was launched. A field team consisting
of a social communicator, a salesman, and a driver began a series of visits to
urban and rural communities carrying the special vessels, disinfectant, and promotional
material in a truck and trailer painted with the ClARO brand name and logo. In
the evenings, the field team projected the video on a 2-by-3 meter screen, gave
project demonstrations, and sold the special vessels and disinfectant to individuals
and stores.
Methods
Six rural communities (476 families, 2,395 persons) were selected
from this region. Nine rural communities (500 families, 1,299 persons) from a
neighbouring geographic region outside of the coverage area of the campaign were
selected as controls. From July through October 1996, we conducted baseline demographic
and water quality surveys and set up an active diarrhea surveillance system for
children <15 years old was set up. Data collection from the surveillance system
began 9 weeks prior to the product launch. A team of anthropologists was based
in 7 of the study communities to investigate behavioural changes in the population.
The social marketing campaign was launched in the region north of Santa Cruz,
Bolivia, in November 1996. Families in intervention communities were offered the
opportunity to receive the special water vessel and disinfectant in exchange for
working on community improvement projects; approximately 50 per cent participated.
A follow-up water quality survey was conducted 3 months after the launch of the
campaign.
Results
Baseline median fecal coliform counts in domestic stored water
in the dry season were 127/100 ml in intervention communities and 195/100 ml in
control communities, a difference that was not statistically significant. Three
months after the launch of the social marketing campaign, in the intervention
communities 50 percent of households reported using the water vessel, 34 per cent
said that they were using the disinfectant, but only 19 per cent had detectable
levels of chlorine in their stored water. Median fecal coliform colony counts
were significantly lower (p<0.05) in domestic stored water in intervention
households (1,960/100 ml) than in contol households (4,000/100 ml); these measurements
were taken during the rainy season when contamination of source water had increased
substantially .Within intervention communities, households that reported using
the special vessel or the disinfectant had significandy lower fecal coliform counts
than households that reported not using these products (p<0.05). During the
9-week prelaunch period, children <15 years old in intervention families had
0.22 episodes of diarrhea per person, and in control families had 0.28 episodes
per person. During the 12-week post-launch period, children in intervention families
had 0.12 episodes person, a reduction of 54.5 per cent, and children in control
families had 0.28 episodes per person. The slope of the curve describing the weekly
incidence of diarrhea in families in intervention communities showed a rate of
decrease of disease that was significantly greater than in control families (p<0.05)
[Figure 1]. The anthropologic study revealed that, in a ranking of village
priorities, clean water and that many regarded diarrhea as a normal occurrence
of childhood.
Figure
1. Weekly family diarrhea Incidence rates in intervention villages participating
in water treatment and storage campaign and in control villages, field trial II,
Santa Cruz, Bolivia, September 1996 - February 1997.
Discussion
The water trearment and storage system
described here
appears to be effective in improving water quality and preventing
diarrheal diseases. Compliance with the use of the special water vessel was high
in both studies. Although compliance with point-of-use water disinfection was
high in Field Trial I, it was much lower in Field Trial II. Consequently, median
levels of contamination of stored water were much higher in intervention households
in Field Trial II than in Field Trial I. This finding can be explained in part
by the relatively law priority the population in Field Trial II placed on clean
water, by the low level of recognition of water's role as a vehicle of disease,
and by the prevalent opinion that diarrhea is not necessarily a disease. To enhance
acceptance of the intervention, we recommend that the social marketing campaign
emphasize education on the association of contaminated water with disease, the
importance of diarrhea prevention, and the proper use of the water treatment and
storage system.
Conclusion
This community-based approach can
be a prevention
straregy for warerborne diseases that is inexpensive, sustainable,
and applicable in a broad variety of developing country settings. Partnerships
between health agencies, nongovernmental groups, and private industry will enable
broad implementation of this low-cost, effective intervention.
References - Mintz
E., et al. Safe water treatment and storage in the
home: a practical new strategy
to prevent waterborne
disease. JAMA 1995;273:948-53. -
Quick, R., et al. Narrow-mouthed water storage vessels
and in situchlorination
in a Bolivian community: a simple method to improve drinking water qualiry. Am.
J. Trap. Med. Hyg. 1996;54:511-16. -
Sobel J, et al., A simple system reduces fecal contamination of street vended
beverages in Guatemala. In: Program and Abstracts, International Night, 46th
Annual Epidemic Intelligence Service (EIS) Conference, Centers for Disease Control
and Prevention, April 15, 1997; Atlanta, GA.
| Suggested citation: Quick
R, et al. A new strategy for waterborne disease transmission. 23rd WEDC Conference.
Durban, South Africa, 1997. |
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