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Typhoid fever from water desalinized using reverse osmosis
S N al-Quarawi1, H E el Bushra, R E Fontaine
1Saudi Arabian Field Epidemiology Training Program, Ministry of Health, Riyadh.
Epidemiology and Infection
|February 1, 1995
Summary
A typhoid fever outbreak in Tabuk City was linked to contaminated water from reverse osmosis (RO) plants, particularly those supplied by a single well. Prechlorination of water for RO systems is crucial to prevent contamination and future outbreaks.
Area of Science:
- Epidemiology
- Public Health
- Water Quality
Background:
- An outbreak of typhoid fever (TF) occurred in Tabuk City, Saudi Arabia, in May 1992.
- The outbreak affected various community segments, including hospital workers, residents, and a military cantonment.
Purpose of the Study:
- To investigate the source and transmission routes of the typhoid fever outbreak in Tabuk City.
- To identify risk factors associated with the outbreak, particularly concerning water sources.
Main Methods:
- Bacteriological confirmation of typhoid fever cases.
- Calculation of attack rates across different districts and population groups.
- Case-control study to assess the association between water sources and typhoid fever, calculating odds ratios (OR) and confidence intervals (CI).
- Microbiological analysis of water samples from various sources.
Main Results:
- 81 confirmed cases of typhoid fever were identified.
- Reverse osmosis (RO) plant water, especially from one well (ASUW), showed the highest odds ratio for contamination (OR = 7.05).
- The aquifer supplying ASUW was located near a sewage collection area, and unchlorinated water samples yielded coliforms.
- The outbreak subsided two weeks after water chlorination began.
Conclusions:
- Contaminated water from specific reverse osmosis (RO) plants, particularly those using unchlorinated well water susceptible to sewage contamination, was the likely source of the typhoid fever outbreak.
- The findings highlight the need for stringent monitoring and prechlorination of water used in RO plants to prevent microbial fouling and safeguard public health.