[Irritable bowel syndrome: frequency and phylogenetic relationship of Blastocystis sp. from Mexican patients]. / Síndrome de intestino irritable: frecuencia y relación filogenética de Blastocystis sp. de pacientes mexicanos.

INTRODUCTION: Recent studies reported increased presence of Blastocystis in patients with Irritable Bowel Syndrome (IBS) and an etiologic role has been proposed. The pathogenic role of Blastocystis is controversial, because it is frequently found not only in individuals with enteric symptoms but also in healthy and asymptomatic subjects. Furthermore, there are few studies of blastocistosis in Mexico. OBJECTIVE: To assess the frequency of Blastocystis sp. in IBS patients using molecular techniques and to describe its phylogenetic relationship with sequences of other countries. METHODS: IBS patients according to Rome III criteria were enrolled. In all patients evaluations included: colonoscopies, coproparasitoscopic studies, coproculture, fecal virus screening. PCR and sequencing for Blastocystis sp. were also performed. RESULTS: We recruited 11 men and 51 women with a mean age of 45.6 (SD ± 15.7) years. Eighty-six percent of the IBS patients presented a normal colonoscopy, 8% showed polyps and 6% diverticular disease. Blastocystis sp. was identified in 25% patients (all of them with normal colonoscopy), while two patients had Endolimax nana and Entamoeba histolytica/E. dispar, respectively. Phylogenetic analysis showed that major sequences of Mexican carriers clustered together with sequences of parasites from Japan and Denmark; furthermore, two sequences from IBS patients were grouped in a single cluster. CONCLUSIONS: Blastocystis sp. was identified in 25% of the IBS patients. Our data support the hypothesis of clonal lineages in distinct geographical areas in the world.

Taenia solium: current understanding of laboratory animal models of taeniosis.

Neurocysticercosis is a public health problem in many developing countries and is the most frequent parasitic disease of the brain. The human tapeworm carrier is the main risk factor for acquiring neurocysticercosis. Since the parasite lodges only in the human intestine, experimental models of Taenia solium taeniosis have been explored. Macaques, pigs, dogs, cats and rabbits are unsuccessful hosts even in immunodepressed status. By contrast, rodents are adequate hosts since tapeworms with mature, pregravid and, in some cases, gravid proglottids develop after infection. In this review, information that has been generated with experimental models of taeniosis due to T. solium is discussed. Initially, the use of the model for immunodiagnosis of human taeniosis and evaluation of intervention measures is summarized. Next, descriptions of tapeworms and comparison of hamsters, gerbils and other mammals as experimental models are discussed, as well as data on the humoral immune response, the inflammatory reaction and the production of cytokines associated to Th1 and Th2 responses in the intestinal mucosa. Finally, evaluation of protection induced against the development of tapeworms by recombinant T. solium calreticulin in hamsters is summarized and compared to other studies.