Detection of Vibrio cholerae O1 in animal stools collected in rural areas of the Limpopo Province

Abstract

Vibrio cholerae (V. cholerae), the causative agent of cholera, has been responsible for various outbreaks worldwide and may be associated with animal faeces. In an attempt to understand the occurrence of this organism in the environment, 230 faecal samples were collected from pigs, chickens, goats, donkeys, cows and pigeons in rural areas of the Limpopo Province. Bacterial DNA was extracted from the faecal samples using a guanidium thiocyanate-based method. The DNA was screened for the presence of the sodB, rfb, FlaE, 16S rRNA and ctxA genes associated with V. cholerae, V. cholerae O1, V. cholerae O139 using 2 multiplex polymerase chain reactions (m-PCR). The V. cholerae sodB gene was detected in 74 of the 230 samples tested. Detection rates for the faecal samples obtained from individual species were as follows: cows (55/74), chickens (8/74), goats (2/74), donkeys (4/74), pigs (3/74) and pigeons (2/74). V. cholerae O1 was detected in (17/74) cow and (3/74) chicken samples, of which (9/17) cow samples and (3/3) chicken samples tested positive for toxigenic V. cholerae O1. The presence of this organism in faecal samples, taken close to water sources used by the villagers, raises the possibility that the causative V. cholerae O1 strain of the most recent outbreak in South Africa was present in the area 6 months prior to the outbreak.

Keywords: Vibrio cholerae, PCR, animal faeces, cholera toxin