Sammendrag
Contamination with Cryptosporidium and Giardia from drinking water sources in a city in Northern
India was assessed. A protocol modified from a standard ISO protocol, which includes filtration,
concentration, separation and detection steps, was tested and showed comparable recovery
efficiencies (Giardia mean ¼ 77.4%, Cryptosporidium mean ¼ 61.8% from the modified protocol,
compared with Giardia mean¼ 61.6%, Cryptosporidium mean¼ 69% from the ISO protocol) at a
substantial cost reduction. This protocol was used for analysing 71 samples of potable water from
different areas of Chandigarh, where sampling locations were divided into groups according to the
population density, which also partially equates with the level of infrastructure. Samples were
collected during (n ¼ 29) and outside the monsoon season (n ¼ 42). Of all samples analysed, 16
(22.5%) were Cryptosporidium- and/or Giardia-positive. Parasites per sample were low (1–10 (oo)
cysts per 10 L), although one sample contained large numbers of Giardia cysts (>1,000). Polymerase
chain reaction analyses on the small subunit ribosomal ribonucleic acid (SSU rRNA), triose-phosphate
isomerase (tpi), glutamate dehydrogenase (gdh) and beta-giardin (bg) gene sequences on Giardiapositive
samples and SSU rRNA on Cryptosporidium-positive samples tended to be unsuccessful,
although Giardia cysts of Assemblages B and C were identified. No association with the season was
detected, but an association with the location of water supply was identified. Samples from areas
with the lowest infrastructure were not associated with higher levels of contamination, but samples
from the middle level were significantly more likely to be contaminated than those from the highest
level of infrastructure. Results indicate that even in a city with a well-developed infrastructure, the
contamination of potable water with protozoan parasites remains a public health risk.
Cryptosporidium, detection, drinking water, Giardia, public health
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