Risk assessment of enteric pathogens in a tropical urban canal network | |
| Author | Tserendorj, Ariuntuya |
| Call Number | AIT Diss. no.EV-11-06 |
| Subject(s) | Sewage--Purification--Anaerobic treatment Factory and trade waste--Purification |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-11-06 |
| Abstract | Enteric pathogens excreted in feces are able to initiate waterborne infections in tropical urban canal networks. The study area was the network of canals linked to the Chao Phraya River, Thailand. Enteric pathogens can be introduced into surface water via the release from the canals. Therefore, it can lead to contamination of a source of drinking water as well as recreational water used for swimming, inland fisheries and irrigation. This study investigated enteric virus (group A Rotavirus), bacteria ( Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes , Salmonella spp., Shigella spp., and V. cholera ) and protozoa ( Cryptosporidium parvum , and Giardia lamblia ) as models for enteric pathogens in environmental samples of surface water. Static microbial health risk assessment employing stochastic data on presently surveyed pathogen concentrations and susceptible portions of exposed populations and literature obtained deterministic data was carr ied out for a number of relevant exposure scenarios. The estimated disease burden for the target pathogens were found to be 2- 3 orders of magnitude greater than the acceptable threshold limit value (10 -6 ) in exposure scenarios including consumption of canal water irrigated vegetables and accidental ingestion of water when fishing or swimming. Due to annual mean value, the highest concentration of pathogen was Shigella spp (1.2 x 10 5 cells per liter) in Can al One followed by Salmonella spp. (2.8 x 10 4 and 1.7 x 10 4 cells per liter) in correspondingly Canal Four and Canal Prem. Interestingly, the highest diarrheal disease burden in terms of lowest infective dose and the highest of probability diarrheal infect ion with coincidence of higher mortality rate (0.005 x 10 -6 ) in annual epidemiological surveillance in Thailand among the target pathogens, were derived from Vibrio cholera (1.36 x 10 -3 , 5.82 x 10 -4 , and 1.42 x 10 -3 in Canal One, Canal Four, and Canal Prem respectively ) across all canals in scenarios of swimming and working in c anal water irrigated crop field. Quantitative R eal Time PCR has proven to be a valuable tool in the enumeration of microbial pathogens in the present multifunctional tropical canal s that are an essential part of livelihood strategies among the low -income and informally employed locals. Whereas the number fluctuation of target protozoan and bacterial enteropathogens satisfactorily correlated with seasonality and spatial distribution of point or nonpoint pollution sources, no pathogen was seen as suitable predictor of several other targets so far considered for monitoring across the three irrigational canals. The compiled pathogen occurrence data has been most useful in modeling infect ion/disease risks and annual disease burden in the study area based on a number of true -to-life exposure scenarios.Th e obtained results w ould be useful for the public health protection and establish ing an integrated pathogens management in Thailand. The se can also serve as rational basis of government efforts aimed at educating the locals of risks associated with the reuse of canal surface waters as taken for granted over generations and heightening the impetus on adequate wastewater treatment among the major polluters in similar places worldwide. Besides, the findings can be useful in the validation of wastewater management/reuse guidelines and also the implementation of surface water safety plans in the study area and similar localities. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-11-06 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Shipin, Oleg V. |
| Examination Committee(s) | Chongrak Polprasert ;Ranamukhaarachchi, S. ;Mason, C.J. |
| Scholarship Donor(s) | The Government of The Netherlands |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2011 |