A SIMPLE FILTRATION METHOD TO REMOVE PLANKTON-ASSOCIATED VIBRIO-CHOLERAE IN RAW WATER-SUPPLIES IN DEVELOPING-COUNTRIES

Plankton to which cells of Vibrio cholerae 01 and/or 0139 were attache d was introduced into 0.5 parts per thousand Instant Ocean microcosms maintained at 25 degrees C. The bulk of the plankton and associated pa rticulates was removed with a filter constructed from either nylon net and one of several different types of sari material, the latter being very inexpensive and readily available in villages in Bangladesh, whe re V. cholerae is endemic. V. cholerae was enumerated before and after filtration to evaluate the efficiency of the filtration procedure. Th e results obtained indicate that 99% of V. cholerae, i.e., those cells attached to plankton, were removed from the water samples. Epidemic s trains of V. cholerae 01 and 0139 from various geographical sources, i ncluding Bangladesh, Brazil, India, and Mexico, were included in the e xperiments. Removal of vibrios from water by this simple filtration me thod was found to yield consistent results with all strains examined i n this study. Thus, it is concluded that a simple filtration procedure involving the use of domestic sari material can reduce the number of cholera vibrios attached to plankton in raw water from ponds and river s commonly used for drinking. Since untreated water from such sources serves as drinking water for millions of people living in developing c ountries (e.g., Bangladesh), filtration should prove effective at redu cing the incidence and severity of outbreaks, especially in places tha t lack fuel wood for boiling water and/or municipal water treatment pl ants. The results of this study provide the basis for determining such reductions, which are to be carried out in the near future.