Occurrence of Vibrio Pathotypes in the Final Effluents of Five Wastewater Treatment Plants in Amathole and Chris Hani District Municipalities in South Africa

Abstract

We assessed the occurrence of Vibrio pathogens in the final effluents of five wastewater treatment plants (WWTPs) located in Amathole and Chris Hani District Municipalities in South Africa over a 12 months period between September 2012 and August 2013 using standard membrane filtration technique followed by cultivation on thiosulphate citrate-bile salts-sucrose (TCBS) agar. The identities of the presumptive Vibrio isolates were confirmed using polymerase chain reaction (PCR) including delineation into V. parahaemolyticus, V. vulnificus and V. fluvialis pathotypes. The counts of Vibrio spp. varied with months in all the study sites and ranged in the order of 101 and 104 CFU/100mL. Vibrio distribution also showed seasonality with high counts being obtained in autumn and spring (p < 0.05). Prevalence of Vibrio spp. among the five WWTPs also differed significantly (p < 0.05). Of the 300 isolates that were confirmed as belonging to the Vibrio genus, 29% (86) were V. fluvialis, 28% (84) were V. vulnificus and 12% (35) were V. parahaemolyticus. The isolation of Vibrio pathogens from the final effluent suggests that this pathogen is in circulation in some pockets of the population and that the WWTPs under study do not efficiently remove bacterial pathogens from the wastewater and consequently are threats to public health.

Vibrio Species in Wastewater Final Effluents and Receiving Watershed in South Africa: Implications for Public Health

“…Proper management of a water treatment facility is pivotal to bettering the quality of water consumed (drinking water) or released (wastewater) into the environment [ 5 ]. In conjunction with the many determinants used to indicate the holistic health or quality of an area, wastewater treatment systems may suffice as a positive indicator of development [ 6 ].…”

“…Many wastewater treatment plants in South Africa still release final effluent containing significant amounts of enteric pathogens such as the Vibrio genus, known for its environmental resilience and relation to disease outbreaks. This results in the impairment of the surrounding receiving water bodies [ 5 , 7 , 8 ]. Wastewater facilities are obliged to make provision for quality management of their wastewater effluents prior to release into surrounding water bodies.…”

“…Studies have already indicated the need to monitor not only the classical pollution indicators, i.e., culturable total or faecal coliforms, but also viral pathogens, toxigenic E. coli , and highly infectious bacterial pathogens such as Vibrio . [ 5 , 8 , 9 , 10 , 11 ].…”

Vibrio cholerae and Cholera biotypes

“…In Haiti in 2010, cholera infection was documented along the Artibonite River (Barzilay et al, 2013, Gaudart et al, 2013. Several studies have reported the isolation and detection of Vibrio species and V. cholerae from a variety of aquatic environments, including drinking water Ries et al, 1992;Shapiro et al, 1999;Downs et al, 1999), freshwater (Hughes et al, 1982;Grim et al, 2010;Madoroba and Momba, 2010;Rashid et al, 2013), wastewater (Momba et al, 2006;Igbinosa et al, 2009;Nongogo and Okoh, 2014), brackish water (Reilly and Twiddy, 1992;El-Lathy, 2009), and sea water (Colwell et al, 1977;1981;Lipp et al, 2003;Gazi et al, 2010;Rashid et al, 2013). There is a relationship between V. cholerae and planktonic crustacean copepods, which leads to the contamination of water.…”

Biological HRPs in wastewater

“…The high incidence of Vibrio cholerae in wastewater is further validated by other Vibrio pathogens to some extent. For example, Nongogo and Okoh (2014) also have found the occurrence of other Vibrio pathogens in the final effluents of five WWTPs located in South Africa over 12 months.…”