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MOLECULAR EPIDEMIOLOGICAL INVESTIGATION OF 2 CYCLOSPORIASIS OUTBREAKS IN VANCOUVER, BRITISH COLUMBIA
Citation:
Piche, R., R. Chen, L. Hoang, J. H. Cross, H.D A. Lindquist, M. W. Fyfe, S. Champange, J. L. IsaccRenton, AND C. L. Ong. MOLECULAR EPIDEMIOLOGICAL INVESTIGATION OF 2 CYCLOSPORIASIS OUTBREAKS IN VANCOUVER, BRITISH COLUMBIA. Presented at Joint meeting of the International Congress of Parasitology & Annual Meeting of the American Society of Parasitologists, Vancouver, British Columbia, Canada, August 4-10, 2002.
Impact/Purpose:
1) Conduct laboratory evaluations of new methods for detection of protozoan parasites.
2) Determine the infective dose of parasitic protozoa to hosts given a variety of models that will assist in estimating the public health significance at various levels of occurrence.
The work in this task will support CCL2 and 3 and will be completed by 9/05.
Description:
Introduction: Cyclospora cayentanensis is a waterborne apicocomplexan protozoan that has been recognized as an emerging parasite. This parasite is the cause of severe diarrhea, which can only be treated with sulfa drugs. Cyclospora caytentanensis is endemic in some parts of the world such as Guatemala and Nepal. In North America, local outbreaks are usually foodborne acquired from the consumption of imported fruits and vegetables. Outbreaks of Cyclospora cayentanensis occurred in BC in 1999 and 2001. The internal transcribed sequence 1 (ITS1) region located between the 18S and the 5.8S rRNA genes is thought to have potential for use in genotyping the protozoan. As part of the outbreak investigation the ITS1 region was sequenced to look for any variation in genotype between different specimens.
Methods: Stool samples were collected from cases in the Cyclospora cayentanensis outbreaks as well as sporadic cases in BC and Nepal. Although the cause of the 1999 outbreak has not been identified, the 2001 outbreak was linked epidemiologically to the consumption of Thai basil. Cycle sequencing of the 18S rRNA and ITS1 genes was performed after PCR amplification and spin-column purification. Sequences were assembled and aligned using Clustal X.
Results: Eighteen stool specimens were analyzed, 6 of which were collected from the 1999 outbreak, 6 from the 2001 outbreak, 5 from BC sporadic and 1 from Nepal sporadic cases. 18S rDNA sequences of five samples collected in the 1999 outbreak, and four samples collected in 2001 were obtained. These sequences showed almost compete homology. The only discrepancy was two single base pair variations in one sample. The ITS1 sequence was obtained for four of the 1999 samples and three of the 2001 samples. The sequences all showed a large degree of homology. The greatest variation was in a 2001 sample obtained from a sporadic case in BC around the time of the 2001 outbreak. This sequence contained insertions and single base pair variation.