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

TY - JOUR

T1 - 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

T2 - an environmental health study

AU - Hounmanou, Yaovi M G

AU - Mdegela, Robinson H

AU - Dougnon, Tamègnon V

AU - Mhongole, Ofred J

AU - Mayila, Edward S

AU - Malakalinga, Joseph

AU - Makingi, George

AU - Dalsgaard, Anders

PY - 2016/10/18

Y1 - 2016/10/18

N2 - BACKGROUND: Cholera, 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.METHODS: From 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).RESULTS: The 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.CONCLUSIONS: Our 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.

AB - BACKGROUND: Cholera, 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.METHODS: From 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).RESULTS: The 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.CONCLUSIONS: Our 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.

KW - Agricultural Irrigation

KW - Animals

KW - Anti-Bacterial Agents

KW - Cross-Sectional Studies

KW - Environmental Health

KW - Fishes

KW - Genes, Bacterial

KW - Microbial Sensitivity Tests

KW - Polymerase Chain Reaction

KW - Ponds

KW - Tanzania

KW - Vegetables

KW - Vibrio cholerae O1

KW - Waste Water

KW - Water Microbiology

KW - Journal Article

U2 - 10.1186/s13104-016-2283-0

DO - 10.1186/s13104-016-2283-0

M3 - Journal article

C2 - 27756420

SN - 1756-0500

VL - 9

SP - 466

JO - BMC Research Notes

JF - BMC Research Notes

IS - 1

ER -