The influence of serial fecal sampling on the diagnosis of giardiasis in humans, dogs, and cats

Uchôa, Flávia Fernandes de Mendonça; Sudré, Adriana Pittella; Macieira, Daniel de Barros; Almosny, Nádia Regina Pereira

doi:10.1590/s1678-9946201759061

Cited by 19 publications

(9 citation statements)

References 32 publications

(36 reference statements)

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“…Based on the above, it is evident that a single negative result may not definitely determine the presence or absence of Giardia spp. in examined dogs and therefore re-examination of fecal samples is necessary to increase the sensitivity of the method [ 48 , 70 , 71 ]. The demand for repeated testing renders microscopy a time-consuming and labor-strenuous method.…”

Section: Discussionmentioning

confidence: 99%

Rapid on-site diagnosis of canine giardiosis: time versus performance

et al. 2020

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Background Infections by protozoans of the genus Giardia are a common cause of diarrhea in dogs. Canine giardiosis constitutes a disease with a zoonotic potential; however, it is often underestimated due to its challenging diagnosis. The objective of the study was to assess the diagnostic performance of an immunochromatographic strip test (SpeedTMGiardia, Virbac, France) comparing it with microscopy (zinc sulfate flotation) by utilizing the combination of an enzyme immunoassay (ProSpecTTMGiardia EZ Microplate Assay, Oxoid Ltd., UK) and the PCR as the gold standard. A positive result in both ELISA and PCR was set as the gold standard. Methods Initially, fecal samples from dogs with clinical signs compatible with giardiosis were tested with the SpeedTMGiardia test and separated into two groups of 50 samples each: group A (positive) and group B (negative). Thereafter, all samples were examined by zinc sulfate centrifugal flotation technique and assayed by the ProSpecTTMGiardia Microplate Assay and PCR. The performance of the SpeedTMGiardia and zinc sulfate centrifugal flotation tests were calculated estimating sensitivity, specificity, and positive and negative likelihood ratio; the chi-square and McNemar tests were used for the comparison of the two methods. Results Giardia cysts were not detected by microscopy in 16 out of the 50 samples (32%) of group A and in none of group B samples. Eight out of 50 samples in group B (16%) were tested positive both with the ProSpecTTMGiardia Microplate Assay and PCR. Fecal examination with the SpeedTMGiardia test was more sensitive (86.2%) than the parasitological method (58.6%, P < 0.001) while the specificity of both methods was 100%. Conclusions The SpeedTMGiardia test is an easy-to-perform diagnostic method for the detection of Giardia spp., which can increase laboratory efficiency by reducing time and cost and decrease underdiagnosis of Giardia spp. infections. This immunochromatographic strip test may be routinely exploited when a rapid and reliable diagnosis is required, other diagnostic techniques are unavailable and microscopy expertise is inefficient. In negative dogs with compatible clinical signs of giardiosis, it is recommended either to repeat the exam or proceed with further ELISA and PCR testing.

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Section: Discussionmentioning

confidence: 99%

Rapid on-site diagnosis of canine giardiosis: time versus performance

et al. 2020

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“…Additionally, the morphology, shedding patterns, or intestinal niche of G. duodenalis may not lend themselves to rectal swab detection as well as for protozoan parasites, such as, Cryptosporidium , for which rectal swabs have been reported to perform comparably to bulk stool. 23 , 25 The intermittent shedding of G. duodenalis is the basis for recommendations to collect fecal samples serially and ideally over three separate days, 20 , 39 – 41 as well as for the parasite’s reputation as challenging to diagnose. 19 In the present study, rectal swab sensitivity did improve through duplicate same-day sample collection.…”

Section: Discussionmentioning

confidence: 99%

Rectal Swabs as an Alternative Sample Collection Method to Bulk Stool for the Real-Time PCR Detection of Giardia duodenalis

Maasch

Arzika

Cook

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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Though bulk stool remains the gold standard specimen type for enteropathogen diagnosis, rectal swabs may offer comparable sensitivity with greater ease of collection for select pathogens. This study sought to evaluate the validity and reproducibility of rectal swabs as a sample collection method for the molecular diagnosis of Giardia duodenalis. Paired rectal swab and bulk stool samples were collected from 86 children ages 0-4 years living in southwest Niger, with duplicate samples collected among a subset of 50 children. Infection was detected using a previously validated real-time PCR diagnostic targeting the small subunit ribosomal RNA gene. Giardia duodenalis was detected in 65.5% (55/84) of bulk stool samples and 44.0% (37/84) of swab samples. The kappa evaluating test agreement was 0.81 (95% CI: 0.54-1.00) among duplicate stool samples (N = 49) and 0.75 (95% CI: 0.47-1.00) among duplicate rectal swabs (N = 48). Diagnostic sensitivity was 93% (95% CI: 84-98) by bulk stool and 63% (95% CI: 49-75) by rectal swabs. When restricting to the lowest three quartiles of bulk stool quantitation cycle values (an indication of relatively high parasite load), sensitivity by rectal swabs increased to 78.0% (95% CI: 64-89, P < 0.0001). These findings suggest that rectal swabs provide less sensitive and reproducible results than bulk stool for the real-time PCR diagnosis of G. duodenalis. However, their fair sensitivity for higher parasite loads suggests that swabs may be a useful tool for detecting higher burden infections when stool collection is excessively expensive or logistically challenging.

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“…Assim sendo, os animais que se enquadram como portadores assintomáticos somados à dificuldade que existe em medicá-los resultam num número maior de animais que não são tratados (COELHO et al, 2009). É fundamental que cães e gatos sejam levados ao veterinário periodicamente, sendo sintomáticos ou assintomáticos, e que o exame coproparasitológico seja realizado em triplicata para aumentar a sensibilidade do teste haja visto que pode haver intermitência na eliminação de ovos, cistos ou oocistos de parasitas nas evacuações (UCHÔA et al, 2017).…”

Section: Discussionunclassified