INTRODUCTION: Ascaridosis and taeniarhynchosis are intestinal parasitic diseases, caused by the multicellular helminthes-Ascaris lumbricoides and Taeniarhynchus saginatus. A. lumbricoides is the largest nematode found in the human intestines with the female organism reaching lengths between 20 and 40 centimeters. T. saginatus is a hermaphroditic cestode reaching lengths from 6 up to 10 meters. Aim: The aim of the current study was to prepare histological tissue sections of both intestinal parasites and to present their specific microscopic structure using different staining techniques. MATERIALS AND METHODS: Two museum preparations of the adult worms, fixed in a 10% formalin solution were used. Histological tissue sections were prepared and stained with the hemalaun-eosin technique, Heidenhein's azan, van Gieson's trichrome and acid orcein after Taenzer-Unna stains. RESULTS: The morphology and positioning of the internal organs of the intestinal parasites were clearly visualized by the hemalaun-eosin technique, while the additional stains allowed the differentiation of some specific morphological elements like the fine structure of the cuticle of A. lumbricoides, cestodal eggs' morphology, etc. CONCLUSION: Although the routine diagnostic procedures for intestinal parasites are more efficient, the histological samples stained with different techniques can provide useful information in the ongoing education of the specialists in human and veterinarian parasitology and biology.

Ентеробиозата е най-разпространената в световен мащаб чревна хелминтна инвазия. Целта на това проучване е да се установи екстензитета на опаразитяване с E. vermicularis на базата на амбулаторни паразитологични изследвания сред пациенти от Варненска област.Материал и методи: Проучени са 32 497 изследвания за ентеробиоза, осъществени по метода на скоч теста за 5 годишен период в една от медико-диагностичните лаборатории на гр. Варна. Анализирана е опаразитеността с Е.vermicularis по пол, възраст и населено място.Резултати: Общият екстензитет на опаразитяване е 0,53%, като с по-голяма честота заболяването се диагностира при децата (0,76%) отколкото при възрастните (0,24%). Най-висок е делът на опаразитените от селата (2,64%), следвани от тези, живеещи в по-малките градове на областта (0,72%). С най-малка честота ABSTRACT Enterobiosis is the most common intestinal helminthic infection worldwide. The objective of this study is to determine the prevalence of E.vermicularis infection established with outpatient laboratory tests among the population of Varna region.Material and Methods: The study includes a total number of 32 497 outpatient tests for enterobiosis performed for 5-year period in one of the parasitological laboratories of Varna city. The prevalence of E.vermicularis infection in assessed by age, sex and residence.Results: The total prevalence of the enterobiosis is 0,53%. The prevalence in children (0,76%) is higher than the extensity in the adult (0,24%) population. The highest occurrence was diagnosed among people living in villages (2,64%), followed by those in small towns (0,72%) of the district. The lowest prevalence is detected in Varna city residents (0,29%). Ключови думи: ентеробиоза, скоч тест, екстензитет на ентеробиозата Conclusions: Due to the easy "person to person" mode of transmission E.vermicularis remains the most common infection in children and in persons living in rural conditions.