Toxigenic Vibrio cholerae O1 in vegetables and fish raised in wastewater irrigated fields and stabilization ponds during a non-cholera outbreak period in Morogoro, Tanzania: an environmental health study

Abstract

BackgroundCholera, one of the world’s deadliest infectious diseases, remains rampant and frequent in Tanzania and thus hinders existing control measures. The present study was undertaken to evaluate the occurrence of toxigenic Vibrio cholerae O1 in wastewater, fish and vegetables during a non-outbreak period in Morogoro, Tanzania.MethodsFrom October 2014 to February 2015, 60 wastewater samples, 60 fish samples from sewage stabilization ponds and 60 wastewater irrigated vegetable samples were collected. Samples were cultured for identification of V. cholerae using conventional bacteriological methods. Isolates were confirmed as V. cholerae by detection of the outer membrane protein gene (ompW) using polymerase chain reaction (PCR). Isolates were further tested for antibiotic susceptibility and presence of virulence genes including, cholera enterotoxin gene (ctx), the toxin co-regulated pilus gene (tcpA) and the haemolysin gene (hlyA).ResultsThe prevalence of V. cholerae in wastewater, vegetables and fish was 36.7, 21.7 and 23.3 %, respectively. Two isolates from fish gills were V. cholerae O1 and tested positive for ctx and tcpA. One of these contained in addition the hlyA gene while five isolates from fish intestines tested positive for tcpA. All V. cholerae isolates were resistant to ampicillin, amoxicillin and some to tetracycline, but sensitive to gentamicin, chloramphenicol, and ciprofloxacin.ConclusionsOur results show that toxigenic and drug-resistant V. cholerae O1 species are present and persist in aquatic environments during a non-cholera outbreak period. This is of public health importance and shows that such environments may be important as reservoirs and in the transmission of V. cholerae O1.

Comprehensive genomic analysis of Vibrio cholerae from three outbreaks in Uganda, 2014 - 2016

“…Despite the World Health Organization (WHO) recommendations (https://www.who.int/topics/cholera/publications/WHO_CDD_SER_91_15/en/) in regards to the management of cholera with oral rehydration salts in addition to antibiotics namely streptomycin, aminoglycosides, trimethoprim, fosfomycin, uoroquinolones, sulphonamides, chloramphenicol/ orfenicol, and tetracyclines, this study reports genotypic resistance in the isolates to the same antibiotics. Similar resistance has been reported in similar studies done in the East African region and elsewhere (5,(15)(16)(17).…”

Transmission and Toxigenic Potential of Vibrio cholerae in Hilsha Fish (Tenualosa ilisha) for Human Consumption in Bangladesh

“…Vibrio cholerae has been isolated from other fish species including fresh water Tilapia species in Israel, Burkina Faso, and Tanzania (Senderovich et al, 2010 ; Traor et al, 2014 ; Hounmanou et al, 2016 ), from Ayu fish in the rivers of Japan (Kiiyukia et al, 1992 ), from the species Rastrineobola argentea and Oreochromis niloticus in Lake Victoria, Kenya (Onyuka et al, 2011 ), and from ornamental fish in Czech Republic (Rehulka et al, 2015 ). Reports also demonstrate isolation of V. cholerae from marine fish species (Scheelbeek et al, 2009 ; Senderovich et al, 2010 ).…”

Antimicrobial Susceptibility among Urban Wastewater and Wild Shellfish Isolates of Non-O1/Non-O139 Vibrio cholerae from La Rance Estuary (Brittany, France)

“…All the 120 isolates of non-O1/non-O139 V. cholerae tested were susceptible to quinolones (nalidixic acid) and phenicols (chloramphenicol) and only one isolate was resistant to trimethoprim-sulfamethoxazole association. More recently, in Tanzania, all the strains of V. cholerae collected in wastewater were resistant to ampicillin and to tetracycline but quite susceptible to phenicol or quinolone (Hounmanou et al, 2016 ).…”