Use of PCR to improve diagnostic yield in an outbreak of cyclosporiasis in Lima, Peru

Abstract

Protozoal diseases are increasingly recognized as the cause of diarrhoeal outbreaks in both developed and developing countries. Cyclospora cayetanensis has been responsible for several epidemics in the last decade. In March 2005, an outbreak of diarrhoea was identified in recruits at the Ancon Naval Base in Lima, Peru. A case-control study was carried out. The overall diarrhoea attack rate was 53% (45/85). Complete data from 52 recruits were available for the analysis; 37 met the criteria for case and 15 for control. The epidemic curve indicated a point source transmission, with cases occurring over 9 days with a peak on the fifth day. Cyclospora cayetanensis was found in 7/37(18.9%) cases and 1/15 (6.7%) controls via standard microscopic techniques. PCR for C. cayetanensis detected 20/35 (57.1%) cases and 3/15 (20%) controls, demonstrating the improved diagnostic yield of this technique. This is the second report to characterize an outbreak of diarrhoea due to C. cayetanensis in Peru among a local population. The epidemiology and clinical course were similar to other reported outbreaks in developed regions. PCR greatly increased the number of C. cayetanensis cases detected during this outbreak, allowing the correct identification of its aetiology.

Molecular Testing for Clinical Diagnosis and Epidemiological Investigations of Intestinal Parasitic Infections

“…In a small study in Peru, nested PCR detected 57.1% positive results in diarrheal cases (20/35) versus only 18.9% positive results in controls (3/15), compared to only 18.9% and 6.7% positive samples in cases and controls, respectively, by microscopy (192). In Egypt, Cyclospora infections were detected in 35 of 140 (25%) diarrheic children by using nested PCR, compared to 17.8% and 22.2% with modified Kinyoun stain and autofluorescence microscopy, respectively (194).…”

“…In 2003, the first TaqMan assays were reported (190,191), enabling the incorporation of Cyclospora into multiplex screening assays to detect and differentiate multiple genera and species of apicomplexa and microsporidia, with the key driving forces being dramatically increased sensitivity compared to that of microscopy (191,192) and the fact that these parasites are rarely encountered in clinical samples in areas where the disease is not endemic. A multiplex PCR method to detect Cyclospora, Cystoisospora, and microsporidia in stool samples based on Luminex technology was recently reported (193).…”

Update on Cyclospora cayetanensis , a Food-Borne and Waterborne Parasite

“…Digestion of the amplified products using the restriction enzyme MnlI (PCR-restriction fragment length polymorphism [PCR-RFLP]) followed by visualization by gel electrophoresis results in patterns that can discriminate these two genera of parasites. Compared to conventional microscopy assays, PCR is a more sensitive diagnostic tool (128).…”

Enteric Protozoa in the Developed World: a Public Health Perspective

“…Various PCR tools have been used that target the internal transcribed spacer region, using primers for the 18S rRNA gene (93,306). These include conventional PCR, reverse transcriptase PCR in combination with agarose gel electrophoresis, and nested PCR (281,304,306,314,450). Some of these techniques for the identification of C. cayetanensis are time-consuming, labor-intensive, and subject to problems of contamination; hence, further studies are needed for the development of highly sensitive rapid tests for this protozoan.…”