title: Diagnosis of intestinal parasites in a rural community of Venezuela: Advantages and disadvantages of using microscopy or RT-PCR.
abstract: A cross-sectional study was carried out to determine the prevalence and diagnostic performance of microscopy and real time PCR (RT-PCR) for 14 intestinal parasites in a Venezuelan rural community with a long history of persistent intestinal parasitic infections despite the implementation of regular anthelminthic treatments. A total of 228 participants were included in this study. A multiplex RT-PCR was used for the detection of Dientamoeba fragilis, Giardia intestinalis, Cryptosporidium sp. and a monoplex RT-PCR for Entamoeba histolytica. Furthermore, a multiplex PCR was performed for detection of Ascaris lumbricoides, Strongyloides stercoralis, Necator americanus and Ancylostoma duodenale. Combined microscopy-PCR revealed prevalences of 49.3% for A. lumbricoides, 10.1% for N. americanus (no A. duodenale was detected), 2.0% for S. stercoralis, 40.4% for D. fragilis, 35.1% for G. intestinalis, and 7.9% for E. histolytica/dispar. Significant increases in prevalence at PCR vs. microscopy were found for A. lumbricoides, G. intestinalis and D. fragilis. Other parasites detected by microscopy alone were Trichuris trichiura (25.7%), Enterobius vermicularis (3.4%), Blastocystis sp. (65.8%), and the non-pathogenic Entamoeba coli (28.9%), Entamoeba hartmanni (12.3%), Endolimax nana (19.7%) and Iodamoeba bütschlii (7.5%). Age- but no gender-related differences in prevalences were found for A. lumbricoides, T. trichiura, G. intestinalis, and E. histolytica/dispar. The persistently high prevalences of intestinal helminths are probably related to the high faecal pollution as also evidenced by the high prevalences of non-pathogenic intestinal protozoans. These results highlight the importance of using sensitive diagnostic techniques in combination with microscopy to better estimate the prevalence of intestinal parasites, especially in the case of D. fragilis trophozoites, which deteriorate very rapidly and would be missed by microscopy. In addition, the differentiation between the pathogenic E. histolytica and the non-pathogenic E. dispar can be attained. However, microscopy remains an important diagnostic tool since it can detect other intestinal parasites for which no PCR is available.
authors.affiliation: Laboratorio de Investigaciones en Bilharzia, Departamento de Parasitología, Facultad de Ciencias de la Salud, Universidad de Carabobo, Campus Carabobo, Valencia, Venezuela. Electronic address: rincani@uc.edu.ve.
authors.forename: Renzo Nino
authors.initials: RN
authors.lastname: Incani
authors.affiliation: Instituto de Investigaciones Biomédicas "Dr. Francisco J. Triana Alonso" (BIOMED) and Departamento de Parasitología, Facultad de Ciencias de la Salud, Universidad de Carabobo, Sede Aragua, Maracay, Venezuela.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ferrer
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Denise
authors.initials: D
authors.lastname: Hoek
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Robbert
authors.initials: R
authors.lastname: Ramak
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Roelfsema
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Utrecht University, Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht, The Netherlands, The Netherlands.
authors.forename: Lapo
authors.initials: L
authors.lastname: Mughini-Gras
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Titia
authors.initials: T
authors.lastname: Kortbeek
authors.affiliation: Center for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Elena
authors.initials: E
authors.lastname: Pinelli
mesh_terms: D000818:Animals; D003430:Cross-Sectional Studies; D005243:Feces / Q000469:parasitology; D005260:Female; D006376:Helminths / Q000302:isolation & purification*; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000175:diagnosis* / Q000469:parasitology; D008297:Male; D008853:Microscopy / Q000379:methods / Q000706:statistics & numerical data*; D060885:Multiplex Polymerase Chain Reaction / Q000706:statistics & numerical data; D010271:Parasites / Q000302:isolation & purification*; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods / Q000706:statistics & numerical data*; D012424:Rural Population; D014687:Venezuela
keywords: Intestinal parasitic infections; Prevalence; Real time PCR; Triple-faeces test; Venezuela