A historical review of the techniques of recovery of parasites for their detection in human stools

Abstract Since the early 20th century, the detection of intestinal parasites has improved with the development of several techniques for parasitic structures recovery and identification, which differ in sensitivity, specificity, practicality, cost, and infrastructure demand. This study aims to review, in chronological order, the stool examination techniques and discuss their advantages, limitations, and perspectives, and to provide professionals and specialists in this field with data that lays a foundation for critical analysis on the use of such procedures. The concentration procedures that constitute the main techniques applied in routine research and in parasitological kits are a) spontaneous sedimentation; b) centrifugation-sedimentation with formalin-ethyl acetate; and c) flotation with zinc sulfate solution. While selecting a technique, one should consider the purpose of its application and the technical-operational, biological, and physicochemical factors inherent in the procedures used in stool processing, which may restrict its use. These intrinsic limitations may have undergone procedural changes driven by scientific and technological development and by development of alternative methods, which now contribute to the improvement of diagnostic accuracy.

A study of intestinal parasites in children of an urban region with excellent sanitary condition reveals high occurrence of Blastocystis spp

Intestinal parasites are among the major causative agents of diseases that affect animals and humans, especially children. In view of this, the current study evaluated the occurrence of these parasitic agents in 737 children in an urban region with excellent sanitation condition of the city of Pedreira, São Paulo, Brazil. Fecal samples from the children were processed with the use of a technique of high diagnostic efficiency (TF-Test®). The diagnosis of these samples resulted in the detection of 557 parasitic structures among eleven genera of parasites, and of 46.4% (342/737) infected children. Blastocystis spp. was found in 69.6% (238/342) of the positive samples and the monoparasitism was accompanied by symptoms in 44 children. Furthermore, 67.8% (232/342) of the infected children had close contact with pets, suggesting a possible zoonotic transmission. Lastly, this study allowed to perform health education to the children, aiming the reduction of new intestinal parasitic infections.

Comparative study of five techniques for the diagnosis of canine gastrointestinal parasites / Estudo comparativo de cinco técnicas para o diagnóstico de parasitos gastrointestinais caninos

Differences in the efficacy of diagnostic techniques employed in the parasitological examination of feces are a limiting factor of this laboratory procedure in the field of Veterinary Parasitology. To verify advances in this type of examination in dogs, we conducted a study using a new technique (TFGII/Dog). Fifty naturally infected dogs were housed in individual stalls, and their feces were evaluated comparatively using this technique and four other conventional techniques. The TFGII/Dog showed high levels of sensitivity and efficiency, surpassing the diagnostic accuracy of the other techniques with a kappa concordance index of 0.739 (Substantial), as opposed to 0.546 (Moderate), 0.485 (Moderate), 0.467 (Moderate), and 0.325 (Fair) of the Spontaneous-Sedimentation, Centrifugal-Flotation in Saturated Zinc Sulfate Solution, Centrifugal-Flotation in Saturated Sugar Solution, and Spontaneous-Flotation in Saturated Sodium Chloride Solution techniques, respectively. The combination of positive results of all techniques comprises eight genera of parasites, with Ancylostoma spp. predominating among helminths, and Cystoisospora spp. among protozoa. The TFGII/Dog technique showed better diagnostic performance, and can therefore be considered an important tool for optimizing the results of laboratory routines and for the control of canine gastrointestinal parasites.

As diferenças na eficácia de técnicas de diagnóstico empregadas no exame parasitológico das fezes é um factor limitante desse procedimento de laboratório no campo da Medicina Veterinária. Com o objetivo de confirmar avanços desse tipo de examinação em cães, a abordagem desse trabalho foi apresentar um estudo com o uso de uma nova técnica (TFGII/Dog). Cinquenta cães naturalmente infectados foram alojados em baias individuais, e suas fezes foram avaliadas comparativamente, usando-se a nova técnica e outras quatro técnicas convencionais. O TFGII/Dog apresentou altos níveis de sensibilidade e eficiência, superando o diagnóstico de outras técnicas com um índice de concordância kappa de 0,739 (Substancial), em oposição a 0,546 (Moderado), 0,485 (Moderado), 0,467 (Moderado) e 0,325 (Pobre) de Sedimentação-Espontânea, Centrífugo-Flutuação em Solução Saturada de Sulfato de Zinco, Centrífugo-Flutuação em Solução Saturada de Açúcar, e Flutuação-Espontânea em Solução Saturada de Cloreto de Sódio, respectivamente. A combinação de resultados positivos das técnicas mostrou oito gêneros de parasitos, com Ancylostoma spp. predominando entre helmintos, e Cystoisospora spp. entre os protozoários. A técnica de TFGII/Dog apresentou melhor desempenho diagnóstico e, portanto, pode ser considerada uma importante ferramenta para otimizar os resultados de rotinas de laboratório e o controle de parasitos gastrintestinais de cães.

Study of oviposition behavior of aedes aegypti in two neighborhoods under the influence of semi-arid climate in the municipality of salinas, state of Minas Gerais, Brazil

The mosquito Aedes aegypti (Diptera: Culicidae) is the main vector of human arborvirus in Brazil.Oviposition behavior is important for the survival and dispersal of A. aegypti. The objective of this studywas to evaluate the oviposition behavior and its relationship to meteorological factors. Twenty ovitrapswere installed in two neighborhoods in the urban area of the city of Salinas, MG, southeastern Brazil.The traps were inspected weekly for the presence of eggs in the water and on the paddle. Simultaneously,regional weather data were analyzed. The results showed the Ovitrap Positivity Index (OPI) variedgreatly, from 0 to 90 percent, between the weeks and boroughs sampled, demonstrating the vector’s greatpopulation fluctuation. Among the analyzed climatic factors, rainfall strongly influenced oviposition,followed by relative air humidity. The number of eggs found on the paddle was significantly higher thanin the water (p<0.05). However, a significant increase of eggs in the water was noticed when the relativehumidity dropped below 40 percent. This seems to be an important behavior to maintain the population inperiods of drought. Through the low number of eggs (<30) found in 56 percent of positive traps, we concludedthat skip-oviposition behavior occurred, contributing to the prevalence of mosquitoes during thesampled period. It is concluded that the occurrence of water oviposition may be higher than described inthe literature, and should be studied due to its evolutionary and epidemiological importance...

O mosquito Aedes aegypti é o principal vetor de arborvírus humanos no Brasil. O comportamentode oviposição é importante para a sobrevivência e dispersão do A. aegypti. O objetivo deste trabalho foi avaliar estes comportamentos e sua relação com fatores climáticos. Instalaram-se vintearmadilhas ovitrampa em dois bairros de Salinas-MG. Todas foram inspecionadas semanalmentepara contagem e identificação dos ovos presentes na água e na palheta. Paralelamente, analisaram-sedados meteorológicos da região. Os resultados mostraram que o Índice de Positividade deOvitrampa (IPO) variou muito (0 por cento a 90 por cento) entre as semanas/bairros amostrados, o que demonstraa grande flutuabilidade populacional do vetor. Dentre os fatores climáticos analisados, o que maisintensamente influenciou a oviposição foi a precipitação, seguida da umidade relativa. O númerode ovos encontrados na palheta foi significativamente maior que na água (p<0,05). Entretanto,observou-se aumento significativo de ovos na água quando a umidade relativa esteve abaixo de 40 por cento.Este parece ser um dado importante para a manutenção das populações em períodos de seca. O baixonúmero de ovos (<30) encontrados em 56 por cento das armadilhas positivas demonstrou a ocorrência docomportamento de skip-oviposition que pareceu contribuir para a prevalência do mosquito em todoo período amostrado. Concluiu-se que a ocorrência de oviposição na água pode ser maior do que odescrito na literatura e deve ser investigada em virtude de sua importância evolutiva e epidemiológica...