Microbiological quality of water spinach grown in the Boeng Cheung Ek lake in Phnom Penh and in...
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Transcript of Microbiological quality of water spinach grown in the Boeng Cheung Ek lake in Phnom Penh and in...
Microbiological quality of water spinach grown in the Boeng Cheung Ek lake in Phnom Penh and in peri-urban aquatic
systems in Hanoi
Vuong Tuan Anh1, Lise Tønner Klank2, Phung Dac Cam1, Anders Dalsgaard2.
1Division of Enteric Infection Diseases, National Institute of Hygiene and Epidemiology, Vietnam; 2Department of Pathobiology, Royal Veterinary and Agricultural University, Denmark
Study objectives
1. To determine the numbers of thermotolerant coliforms, helminth eggs and protozoan parasites in water spinach grown in Boeng Cheung Ek (BCE) lake, Phnom Penh and at two peri-urban communes in Hanoi, including samples harvested with and without wastewater (ww) exposure
2. To assess the association between microbiological water quality and of water spinach
Sites and methodology
Sampling sites and schedule
Phnom Penh: 2 inlets, 1 outlet of BCE lake and the control site (a small pond); all sites sampled four times; with and without ww exposure of plants
Hanoi: one ww-irrigated site, one rainwater-irrigated site, 6 fields at each site sampled during wet and dry seasons (duplicate samples)
Number of sample collected: 68 plant samples in Phnom Penh; 216 plant samples in Hanoi
Sites and methodology
Parameters: thermotolerant coliforms, E. coli, helminth eggs (Ascaris lumbricoides, Trichuris trichiura, hookworm) and protozoa (Giardia intestinales, Cryptosporidium parvum and Cyclospora spp.)
Sample analysis: Cambodian Pasteur Institute and NIHE
Laboratory methods: MPN for thermotolerant coliforms and helminth egg enumeration according to WHO manual 1996, Immuno-flourescent microscopy to detect protozoan parasites
Phnom Penh results: Numbers of thermotolerant coliforms and E. coli in water spinach
6181818N =
location of sampling
controlSteung ChrovTrabekJICA
ther
mot
oler
ant c
olifo
rms
10
8
6
4
239
2184N =
location of sampling
controlSteung ChrovTrabekJICA
E.co
li lo
g
7
6
5
4
3
2
1
0
Phnom Penh: protozoan parasites in water spinach (total 68 samples)
0
2
4
6
8
10
12
JICA Trabek Steung Chrov Control
Nu
mb
er
of
po
sit
ive
sa
mp
les
Cyclospora Cryptosporidium Giardia
Phnom Penh: helminth eggs qualitative analysis
Sampling location
Hook-worm
Ascaris spp.
Trichuris spp.
JICA1 0/12 0/12 0/12
Trabek1 0/12 1/12 0/12
Steung Chrov2 1/12 2/12 0/12
Control 0/8 1/8 0/8
1 inlet; 2 outlet
Phnom Penh: nos of thermotolerant coliforms in water spinach exposed versus non-exposed to ww during harvest
3999 3999N =
location of sampling
ControlSteung ChrovTrabekJICA
the
rmo
tole
ran
t co
lifo
rms
log
10
8
6
4
2
un-exposure of w ater
exposure of w ater
14
21
13
Correlation of microbiological quality of water and water spinach
25252525 6181818N =
location of sampling
Control (veg)
Steung Chrov
Trabek
JICA
control (w ater)
the
rmo
tole
ran
t co
lifo
rms
log
10
8
6
4
2
w ater spinach
w ater
90
9486
73117
77
81
39
Hanoi results: Thermotolerant coliforms in water spinach (log MPN/g)
1,00E+00
1,00E+01
1,00E+02
1,00E+03
1,00E+04
1,00E+05
WW-wet season WW-dry season Non-WW-wet season Non-WW-dry season
A=harvested by NIHE B=harvested by farmer, no postharvest washing C=harvested by farmer, plus postharvest washing
BL=after storage overnight, before leaving for market D=upon arrival to market
Hanoi results: Seasonal occurrence of protozoan parasites in ww-irrigated and rainwater-irrigated water spinach (%) (total of 216 samples) in peri-urban Hanoi
6.7
3.3
18.8
45.8
10.0
11.9
6.3
33.3
6.7
11.9
2.1
6.3
0
5
10
15
20
25
30
35
40
45
50
WW-April-May WW-Nov-Dec Non-WW-April-May Non-WW-Nov-Dec
%
Cyclospora
Giardia
Cryptosporidium
Hanoi results: helminth egg qualitative analysis
Sampling location
Hook-worm
Ascaris spp.
Trichuris spp.
WW-irrigated site – Wet
season (n=48) 0/48 1/48 0/48WW-irrigated site – Dry
season (n=48) 0/48 2/48 0/48Non-WW-irrigated site –
Wet season (n=60) 0/60 0/60 0/60Non-WW-irrigated site –
Wet season (n=60) 0/60 0/60 0/60
Phnom Penh study – Conclusions
• Thermotolerant coliforms– Relatively higher levels (105-106 /g) on water
spinach• Protozoan parasites
– Giardia is most prevalent, particularly in plant samples collected at inlets
• Helminth eggs– Very low levels detected at all sampling sites
Hanoi study – Conclusions
• Thermotolerant coliforms– Relatively low levels on water spinach (<104/g)– No apparent differences between seasons
• Protozoan parasites– Higher prevalences during dry season at WW-site– Giardia is most prevalent, particularly at WW-site– Cryptosporidium: high levels during dry season at WW-site– Cyclospora is less prevalent than Giardia and
Cryptosporidium, but is present at both sites and during both seasons
• Helminth eggs– Very low levels detected at both sites, no apparent
difference between seasons
Study completion and remaining work
• Data analysis
• PCR analysis for identification and characterization puruposes; and subtyping of protozoans
• Preparation and submission of manuscripts (1-2 MS)
Acknowledgements
• Staff of the Faculty of Fisheries, at the Royal University of Agriculture, in particular Chouk Borin, and at the Pasteur Institute in Phnom Penh for excellent technical assistance in sample and data collection
• The National Inst of Hygiene and Epidemiology (NIHE) for providing laboratory facilities and good laboratory support for sample analyses
• EU-INCO-DEV (PAPUSSA), DANIDA (grant no. 104.Dan.8.L ”Sanitary Aspects of Drinking Water and Wastewater Reuse in Vietnam”) and KVL for financial support