Isolation and identification of Giardia lamblia cysts from surface waters of Rasht city

Giardia Lamblia is a protozoan parasite with global spread in the human population. Identification, diagnosis and determination of the incidence of the infectious agent can be valuable to control the possible sources of spread of this infectious agent in human communities. Therefore, the aim of this study was isolation and diagnosis of Giardia cysts from surface waters of Rasht based on microscopic and molecular methods.
This Cross-sectional study was performed on 45 samples of surface water collected from rivers and wetlands in the vicinity of Rasht. The samples were concentrated using nitrocellulose membrane filters. Giardia cysts were sought in concentrated deposits using Lugol staining. Giardia lamblia genome amplification was done by specific primers on DNA extracted from sediment samples using phenol-chloroform method.
From 45 surface water samples, 15 (33.33%) were positive based on concentration and microscopic observation and 18 (40%) were positive in PCR. PCR had 100% sensitivity and 90% specificity in comparison with the standard staining method.
In detection of Giardia lamblia cysts from concentrated water samples, PCR is more sensitive and specific than microscopy. Given the common use of water resources for agriculture, use of sanitary methods of pathogen control including preventing human sewage from entering into any water source is recommended.