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.

Spatial and seroepidemiology of canine visceral leishmaniasis in an endemic Southeast Brazilian area

Abstract INTRODUCTION: Canine visceral leishmaniasis (CVL) is a public health problem, and its prevalence is associated with the coexistence of vectors and reservoirs. CVL is a protozoonosis caused by Leishmania infantum that is endemic in the southeast region of Brazil. Thus, vector and canine reservoir control strategies are needed to reduce its burden. This study aimed to verify the CVL seroprevalence and epidemiology in a municipality in Southeast Brazil to initiate disease control strategies. METHODS: A total of 833 dogs were subjected to Dual Path Platform (DPP) testing and enzyme-linked immunosorbent assays. For seropositive dogs, epidemiological aspects were investigated using a questionnaire and a global position system. The data were submitted to simple logistic regression, kernel estimation, and Bernoulli spatial scan statistical analysis. RESULTS: The overall CVL-confirmed seroprevalence was 16.08%. The 28.93% in the DPP screening test was associated with dogs maintained in backyards with trees, shade, animal and/or bird feces, and contact with other dogs and cats, with sick dogs showing the highest chances of infection (odds ratio, 2.6; 95% confidence interval, 2.38-1.98), especially in residences with elderly people. A spatial analysis identified two hotspot regions and detected two clusters in the study area. CONCLUSIONS: Our results demonstrated that residences with elderly people and the presence of trees, shade, feces, and pet dogs and cats increased an individual's risk of developing CVL. The major regions where preventive strategies for leishmaniasis were to be initiated in the endemic area were identified in two clusters.

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.

A new laboratorial method for the diagnosis of gastrointestinal parasites in dogs / Um novo método laboratorial para diagnóstico de parasitos gastrointestinais em cães

In this study, we aimed to introduce a new technique called TF-Test Modified/Dog for the diagnosis of gastrointestinal parasites in dogs. Fecal samples from 106 dogs were processed by the technique TF-Test Modified/Dog and the techniques of centrifugation-flotation in zinc sulfate, simple-flotation by saturated solution of sodium chloride, direct microscopy exam and TF-Test Conventional. Sensitivity was higher in the TF-Test Modified/Dog (98.41%), followed by flotation in saturated zinc sulfate (77.78%), TF-Test Conventional (73.02%), flotation by saturated sodium chloride (55.55%), and direct microscopy exam (30.16%). The diagnostic efficiency varied from 58.49% to 99.06%, with the highest value also obtained by the new proposed technique. Efficiency level of 99.06% with kappa index 0.979 (almost perfect) was obtained with the TF-Test Modified/Dog. These results represent significant statistical gains (P < 0.05) of 20.63% in sensitivity and 12.27% in efficiency over the best among the other techniques ­ flotation by saturated zinc sulfate, whose kappa index was 0.738, much lower than that of the TF-Test Modified/Dog. All techniques presented 100% specificity. In this sense, the high sensitivity of the TF-Test Modified/Dog makes it suitable for epidemiological surveys of gastrointestinal parasitosis in dogs, zoonoses control and preventive surveillance programs.

O objetivo deste estudo foi introduzir a nova técnica TF-Test Modified/Dog para diagnóstico de parasitos gastrointestinais em cães. Amostras fecais de 106 cães foram processadas pela técnica de TF-Test Modified/Dog e também por técnicas de centrifugação-flutuação em sulfato de zinco, flutuação simples em solução saturada de cloreto de sódio, exame microscópico direto e TF-Test Convencional. A sensibilidade foi maior no TF-Test Modified/Dog (98,41%), seguido por centrífugo-flutuação em solução de sulfato de zinco (77,78%), TF-Test Convencional (73,02%), flutuação em solução saturada de cloreto de sódio (55,55%), e exame microscópico direto (30,16%). A eficiência diagnóstica variou de 58,49% a 99,06%, com maior valor obtido pela nova técnica. Foi obtido com o TF-Test Modified/Dog eficiência de 99,06%, com índice kappa de 0,979 (Quase perfeito). Estes resultados representam ganhos estatisticamente significativos (P < 0,05) de 20,63% de sensibilidade e 12,27% de eficiência sobre a melhor entre as outras técnicas empregadas, centrífugo-flutuação em solução de sulfato de zinco, cujo índice kappa foi 0,738, bem menor do que o TF-Test Modified/Dog. Todas as técnicas apresentaram especificidade de 100%. Nesse sentido, a sua alta sensibilidade o torna adequado para levantamentos epidemiológicos das parasitoses gastrointestinais em cães, bem como para programas de controle de zoonoses e de vigilância preventiva.

Avaliação do kit TF-Test para o diagnóstico das infecções por parasitas gastrintestinais em ovinos / The evaluation of TF-Test kit for diagnosis of gastrointestinal parasite infectionss in sheep

Este estudo teve como objetivos padronizar o kit TF-Test para a quantificação de ovos de parasitas gastrintestinais de ovinos e compará-lo ao método de Gordon & Whitlock modificado (G&W). Vinte quatro cordeiros confinados foram infectados artificialmente com Haemonchus contortus, durante 12 semanas, até o abate, quando foram colhidas amostras fecais e realizada a identificação e contagem dos parasitas abomasais. Nestes animais, ovos de H. contortus foram detectados em 95,8% das amostras fecais por ambos os testes (P>0,05). Os coeficientes de correlação (r) entre a carga parasitária (CP) e os valores de OPG obtidos pelos métodos de G&W e TF-Test foram, respectivamente, de r=0,52 e r=0,51 (dados não transformados) e r=0,85 e r=0,87 (dados transformados em log). Outras 100 amostras fecais foram colhidas de ovinos naturalmente infectados. Nas amostras destes animais, os testes G&W e TF-Test propiciaram o diagnóstico de ovos de estrongilídeos em 85% e 86% das amostras, respectivamente (P>0,05). Pelo TF-Test e pelo G&W, oocistos de Eimeria foram detectados em 33% e em 12% das amostras (P<0,001) e ovos de Strongyloides spp. em 15% e 5% das amostras, respectivamente (P<0,05). Ambos os testes foram precisos para o diagnóstico de estrongilídeos gastrintestinais, porém, o TF-Test foi superior para o diagnóstico de oocistos de Eimeria spp. e de ovos de Strongyloides spp., mas, por outro lado, subestimou o número de ovos de estrongilídeos presente nas amostras.

This study was performed to standardize parasite egg counting in feces of sheep by TF- Test, in addition to compare this test to the Gordon & Whitlock technique (G&W). Twenty-four lambs were artificially infected with Haemonchus contortus throughout 12 weeks. At the end of this time, faecal samples were taken and animals were slaughtered for worm identification and counting. G&W and TF-Test methods were carried out on each fecal sample. Both tests showed Haemonchus eggs in 95.8% of the samples (P>0.05). The corre1ation coefficients (r) between fecal egg counts (FEC) using G&W x Total Worm Count (TWC) were r=0.52 (not transformed data) and r=0.85 (transformed data); between FEC by TF-Test x TWC were r=0.51 (not transformed data) and r=0.87 (transformed data). Other 100 fecal samples were taken from naturally infected sheep. In these animals, the G&W and TF-Test methods showed 85% and 86% of fecal samples positive for Strongylidea eggs, respectively (P>0.05). Also in those animals, Eimeria oocysts were found in 33% of fecal samples by TF-Test, whereas in the G&W only 12% were positive (P<0.001). For Strongyloides spp., TF-Test showed 15% of positive fecal samples, whereas G&W showed 5% (P<0.05). In conclusion, both methods were efficient to diagnose gastrointestinal nematodes and TF-Test was superior to diagnose oocysts of Eimeria spp. and eggs of Strongyloides spp; conversely, Strongylidea eggs counting using TF-Test was underestimated.

Coprotest quantitativo: quantificação de ovos de helmintos em amostras fecais utilizando-se sistema de diagnóstico comercial / Quantitative Coprotest®: quantification of helminth eggs in fecal samples by commercial diagnostic kit

A técnica coproparasitológica de concentração em formol acetato de etila foi empregada para a quantificaçäo de ovos de helmintos. O método quantitativo proposto foi padronizado utilizando-se o sistema comercial Coprotest e amostras fecais contendo diferentes cargas de ovos de Ascaris lumbricoides. Para a comparação do Coprotest quantitativo com outros métodos de quantificação de ovos, foi preparada em laboratório uma série de amostras fecais, com carga decrescente de ovos de A. lumbricoides, Trichuris trichiura e Schistosoma mansoni. Discutem-se as vantagens de se empregar um método capaz de detectar maior número de espécies de helmintos, além de protozoários, e que permita, concomitantemente, estimar a intensidade das infecções por geo-helmintos e S. mansoni nas populações. O Coprotest quantitativo mostrou ser de aplicaçäo viável, fornecendo resultados comparáveis a outros métodos quantitativos já descritos na literatura