The incidence of Vibrio cholerae in water, animals and birds in Kent, England

Between 1976 and 1979 several surveys were carried out in Kent, England, to establish the incidence of Vibrio cholerae in the aquatic environment. Vibrio cholerae occurred sporadically in all types of water during the summer but only in very low numbers in water containing <5 mmol Na⁺/litre. Highest numbers of up to 700 colony-forming units/ml appeared regularly in static brackish water containing 25–200 mmol Na⁺/litre. They were not introduced by sewage contamination of the water and there was no correlation between the counts of Escherichia coli and V. cholerae. A wide range of serovars including O1 was isolated. Vibrio cholerae was not isolated from sheep faeces but was detected in 6% of cloacal swabs taken from gulls caught at times when V. cholerae could not be isolated from water. It was concluded that: the presence of these organisms in the environment in Kent does not present any significant risk to health; aquatic birds may be vectors of V. cholerae; V. cholerae occurs naturally in static brackish water.