Padronização de metodologia para detecção de ovos e larvas de helmintos em alface

• Ano de defesa: 2012
• Autor(a) principal: Flaviane Cristina Lopes Matosinhos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Parasitologia
• Link de acesso: http://hdl.handle.net/1843/BUOS-8UBLQT

Globalization of food trade, ease of international travel and increasing numbers of immunocompromised individuals are some of the factors attributed to the increase of food-borne parasitic infections. The methods described to assess contamination by helminths and protozoa in plants are derived from known effective methods for other matrices such as water and feces, but without presenting fundamental studies on their performance when adapted for vegetables. The method recommended by the FDA (Food and Drug Administration) has a recovery rate of only 10% for eggs of Ascaris sp and Trichuris sp. Given these facts, the study proposed here seeks to improve the knowledge about the diagnosis of parasitic contaminants, aiming to standardize a method for detecting helminth eggs and larvae in lettuce, estimating their percentage of recovery. Previously sanitized lettuces were artificially contaminated at different levels, with eggs of Ascaris suum and hookworms, and larvae of Ancylostoma ceylanicum. To standardize the method, were tested: liquid extractors, vegetable washing steps and time to spontaneous sedimentation. Higher percentages of recovery of eggs and larvae were obtained using 1M glycine as liquid extractor, manual shaking for 3 minutes and 2 hours of sedimentation. Following these standard conditions, there were ten replicates for each of the five levels of artificial contamination (n = 50), yielding an average recovery of 62.6% (± 20.2) for eggs of A. suum, 51.9% (± 20.0) eggs from hookworms and 50.0% (± 27.3) for larvae of A. ceylanicum. In order to test the performance of the method, tests were also performed with another type of matrix and collaborative analytical studies by different laboratories, with satisfactory results. For additional identification of parasites a polymerase chain reaction (PCR) was tested successfully, starting directly from the egg, without prior extraction of DNA followed by PCR-RFLP (polymorphism by restriction fragment length), which enables the specific identification of the amplified material. The method of identification of helminth eggs and larvae proposed in this study proved to be simpler and more efficient in comparison to procedures previously published, which increases their potential contribution to health surveillance and epidemiological studies.