The Specific Gravity of Hookworm Eggs

Sawitz, Willi; Tobie, John E.; Katz, Gertrud

doi:10.4269/ajtmh.1939.s1-19.171

Cited by 9 publications

(4 citation statements)

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“…Moitinho and Ferreira (1984), carrying out similar work, did not find out any reduction on the floatability of Ancylostomidae eggs by using refrigeration. These data are opposed to those of Sawitz et al (1939), according to whom the permanence of stools in refrigerator reduces the floatability of eggs of this helminth.…”

Section: Discussioncontrasting

confidence: 42%

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Influence of Refrigeration and Formalin on the Floatability of Giardia duodenalis Cysts

Moitinho

Bértoli

Guedes

et al. 1999

Mem. Inst. Oswaldo Cruz

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Section: Discussioncontrasting

confidence: 42%

“…Adopted by Silva (1984) and Moitinho and Ferreira (1992) in researches concerning specific gravities of samples of, respectively, helminth eggs and cysts of Giardia duodenalis and Entamoeba coli, this technique is based on the work of Sawitz et al (1939) who used analogous methodology to investigate the floatability of Ancylostomidae eggs.…”

mentioning

confidence: 99%

Influence of Refrigeration and Formalin on the Floatability of Giardia duodenalis Cysts

Moitinho

Bértoli

Guedes

et al. 1999

Mem. Inst. Oswaldo Cruz

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“…The intestinal parasites that did not have reproducible results in the study of repeatability are characterized by presenting parasitic forms of small size (Blastocystis spp., the diameter of which may vary between 2 and 200 m) (Tan, 2008) and low specific density (hookworm, with a specific density of approximately 1.055 in zinc sulphate solution) (Sawitz et al, 1939). Size and density are important characteristics for the determination of the dynamics of sedimentation of parasitic forms in liquid media.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the performance of two spontaneous sedimentation techniques for the diagnosis of human intestinal parasites in the absence of a gold standard

et al. 2014

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Performance evaluation of diagnostic tests is critical in the search for accurate diagnoses. A gold standard test is usually absent in parasitology, thus rendering satisfactory assessment of diagnostic accuracy difficult. Moreover, reliability (assessed by the study of repeatability) is a rarely studied characteristic of diagnostic tests. This study compared and evaluated the performance (repeatability, concordance and accuracy) of the spontaneous sedimentation technique (SST) and the Paratest for the diagnosis of Giardia lamblia, Entamoeba histolytica complex, Blastocystis spp., Ascaris lumbricoides, hookworm, Trichuris trichiura and Calodium hepaticum. Fecal samples of 143 individuals were separated into three replicates for each test. Concordance and homogeneity of the results between replicates of each test and between tests were evaluated. Proportions of positives, sensitivity and specificity were estimated using a Bayesian Latent Class Model. High repeatability of both tests was found for the detection of intestinal parasites, except for Blastocystis spp. and hookworm. Concordance between tests was generally high (concordance correlation coefficient, 0.72-0.88), except for Blastocystis spp., hookworm and T. trichiura. The Paratest detected more cases of Blastocystis spp. and fewer of hookworm than the SST. The tests were quite discordant in the detection of T. trichiura. A low sensitivity (39.4-49.2% for SST, 35.8-53.8% for Paratest) and a high specificity (93.2-97.2%) were found for both tests. The Paratest presented a slightly higher sensitivity for the diagnosis of Blastocystis spp. (53.8%), and SST did so for hookworm (49.2%). This is the first study on repeatability and accuracy (using a Bayesian approach) of two spontaneous sedimentation techniques. These results suggest underdiagnosis of little dense parasitic forms due to technical limitations in both tests. We conclude that the combined study of repeatability, concordance and accuracy is a key strategy for better evaluation of the performance of tests and is also useful for the identification of technical limitations.

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“…The principle of the technique is based on the difference between the density of a specific flotation solution and that of parasitic structures such as eggs, helminth larvae, and protozoan cysts and oocysts. Several tests with different solutes resulted in a variety of density parameters that encompassed the structures of the several species of intestinal parasites until research established consensual values between 1.036 g/mL and 1.225 g/ mL [74][75][76][77] . The spontaneous flotation technique was then performed with saturated solutions with a density between 1.18 g/mL and 1.27 g/mL, depending on the reagent used 8 .…”

Section: Spontaneous Flotation and Centrifugal Flotationmentioning

confidence: 99%

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

Soares

Benitez

Santos

et al. 2020

Rev. Soc. Bras. Med. Trop.

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Since the early 20 th 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.

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The Specific Gravity of Hookworm Eggs

Cited by 9 publications

References 0 publications

Influence of Refrigeration and Formalin on the Floatability of Giardia duodenalis Cysts

Influence of Refrigeration and Formalin on the Floatability of Giardia duodenalis Cysts

Comparison of the performance of two spontaneous sedimentation techniques for the diagnosis of human intestinal parasites in the absence of a gold standard

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

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