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Evaluating the accuracy of molecular diagnostic testing for canine visceral leishmaniasis using latent class analysis.

Solcà Mda S, Bastos LA, Guedes CE, Bordoni M, Borja LS, Larangeira DF, da Silva Estrela Tuy PG, Amorim LD, Nascimento EG, de Sá Oliveira GG, dos-Santos WL, Fraga DB, Veras PS - PLoS ONE (2014)

Bottom Line: The specificity achieved by qPCR was 76.7% (CI 73.7-79.6) for splenic aspirates obtained from the greater sample.This confirms that the splenic aspirate is the most effective type of tissue for detecting L. infantum infection.Additionally, we demonstrated that LCA could be used to generate a suitable gold standard for comparative CVL testing.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Patologia e Biointervenção, Centro de Pesquisa Gonçalo Moniz-Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.

ABSTRACT
Host tissues affected by Leishmania infantum have differing degrees of parasitism. Previously, the use of different biological tissues to detect L. infantum DNA in dogs has provided variable results. The present study was conducted to evaluate the accuracy of molecular diagnostic testing (qPCR) in dogs from an endemic area for canine visceral leishmaniasis (CVL) by determining which tissue type provided the highest rate of parasite DNA detection. Fifty-one symptomatic dogs were tested for CVL using serological, parasitological and molecular methods. Latent class analysis (LCA) was performed for accuracy evaluation of these methods. qPCR detected parasite DNA in 100% of these animals from at least one of the following tissues: splenic and bone marrow aspirates, lymph node and skin fragments, blood and conjunctival swabs. Using latent variable as gold standard, the qPCR achieved a sensitivity of 95.8% (CI 90.4-100) in splenic aspirate; 79.2% (CI 68-90.3) in lymph nodes; 77.3% (CI 64.5-90.1) in skin; 75% (CI 63.1-86.9) in blood; 50% (CI 30-70) in bone marrow; 37.5% (CI 24.2-50.8) in left-eye; and 29.2% (CI 16.7-41.6) in right-eye conjunctival swabs. The accuracy of qPCR using splenic aspirates was further evaluated in a random larger sample (n = 800), collected from dogs during a prevalence study. The specificity achieved by qPCR was 76.7% (CI 73.7-79.6) for splenic aspirates obtained from the greater sample. The sensitivity accomplished by this technique was 95% (CI 93.5-96.5) that was higher than those obtained for the other diagnostic tests and was similar to that observed in the smaller sampling study. This confirms that the splenic aspirate is the most effective type of tissue for detecting L. infantum infection. Additionally, we demonstrated that LCA could be used to generate a suitable gold standard for comparative CVL testing.

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Sensitivity of the different diagnostic techniques employed in the biological samples obtained from Jequié animals (n = 51).Vertical bars represent the 95% confidence intervals. Sensitivity values were obtained using the latent variable as the gold standard.
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pone-0103635-g001: Sensitivity of the different diagnostic techniques employed in the biological samples obtained from Jequié animals (n = 51).Vertical bars represent the 95% confidence intervals. Sensitivity values were obtained using the latent variable as the gold standard.

Mentions: The sensitivity of the tests employed in Jequié to diagnose L. infantum infection was assessed employing the latent variable obtained by LCA as the gold standard (Figure 1). Splenic aspirates provided the highest sensitivity of the available tissues sampled achieving 95.8% (95%CI 90.4–100) of sensitivity. The sensitivity attained in other tissues ranged from 80% to 30% as follows: lymph node fragments 79.2% (95%CI 68–90.3), skin fragments 77.3% (95%CI 64.5–90.1), blood 75% (95%CI 63.1–86.9), bone marrow aspirates 50% (95%CI 30–70), left eye swab 37.5% (95%CI 24.2–50.8), and right eye swab 29.2% (95%CI 16.7–41.6). It was not possible to calculate splenic qPCR specificity since only one sample tested negative in this method. Specificity of the other tissues achieved 66.7% for lymph node fragments (95%CI 53.7–79.6) as well as for bone marrow aspirates (95%CI 47.8–85.6), 63% (95%CI 49.7–76.2) for right and left eye swabs, 42.1% (95%CI 27–57.2) for skin fragments and 14.8% (95%CI 5.1–24.6) for blood. Considering the other diagnostic tests, the sensitivity of the serological tests was 100% for the DPP CVL, followed by 79.2% (95%CI 68–90.3) for the in-house ELISA, 65.2% (95%CI 51.7–78.7) for EIE CVL, while sensitivity for the splenic aspirate culturing was 54.2% (95%CI 40.5–67.8). The specificity was highest for DPP CVL 100%, followed by splenic parasite cultures 81.5% (95%CI 70.8–92.1), EIE CVL 76% (95%CI 63.9–88.1), in-house ELISA 44.4% (95%CI 30.8–58.1).


Evaluating the accuracy of molecular diagnostic testing for canine visceral leishmaniasis using latent class analysis.

Solcà Mda S, Bastos LA, Guedes CE, Bordoni M, Borja LS, Larangeira DF, da Silva Estrela Tuy PG, Amorim LD, Nascimento EG, de Sá Oliveira GG, dos-Santos WL, Fraga DB, Veras PS - PLoS ONE (2014)

Sensitivity of the different diagnostic techniques employed in the biological samples obtained from Jequié animals (n = 51).Vertical bars represent the 95% confidence intervals. Sensitivity values were obtained using the latent variable as the gold standard.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4116254&req=5

pone-0103635-g001: Sensitivity of the different diagnostic techniques employed in the biological samples obtained from Jequié animals (n = 51).Vertical bars represent the 95% confidence intervals. Sensitivity values were obtained using the latent variable as the gold standard.
Mentions: The sensitivity of the tests employed in Jequié to diagnose L. infantum infection was assessed employing the latent variable obtained by LCA as the gold standard (Figure 1). Splenic aspirates provided the highest sensitivity of the available tissues sampled achieving 95.8% (95%CI 90.4–100) of sensitivity. The sensitivity attained in other tissues ranged from 80% to 30% as follows: lymph node fragments 79.2% (95%CI 68–90.3), skin fragments 77.3% (95%CI 64.5–90.1), blood 75% (95%CI 63.1–86.9), bone marrow aspirates 50% (95%CI 30–70), left eye swab 37.5% (95%CI 24.2–50.8), and right eye swab 29.2% (95%CI 16.7–41.6). It was not possible to calculate splenic qPCR specificity since only one sample tested negative in this method. Specificity of the other tissues achieved 66.7% for lymph node fragments (95%CI 53.7–79.6) as well as for bone marrow aspirates (95%CI 47.8–85.6), 63% (95%CI 49.7–76.2) for right and left eye swabs, 42.1% (95%CI 27–57.2) for skin fragments and 14.8% (95%CI 5.1–24.6) for blood. Considering the other diagnostic tests, the sensitivity of the serological tests was 100% for the DPP CVL, followed by 79.2% (95%CI 68–90.3) for the in-house ELISA, 65.2% (95%CI 51.7–78.7) for EIE CVL, while sensitivity for the splenic aspirate culturing was 54.2% (95%CI 40.5–67.8). The specificity was highest for DPP CVL 100%, followed by splenic parasite cultures 81.5% (95%CI 70.8–92.1), EIE CVL 76% (95%CI 63.9–88.1), in-house ELISA 44.4% (95%CI 30.8–58.1).

Bottom Line: The specificity achieved by qPCR was 76.7% (CI 73.7-79.6) for splenic aspirates obtained from the greater sample.This confirms that the splenic aspirate is the most effective type of tissue for detecting L. infantum infection.Additionally, we demonstrated that LCA could be used to generate a suitable gold standard for comparative CVL testing.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Patologia e Biointervenção, Centro de Pesquisa Gonçalo Moniz-Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.

ABSTRACT
Host tissues affected by Leishmania infantum have differing degrees of parasitism. Previously, the use of different biological tissues to detect L. infantum DNA in dogs has provided variable results. The present study was conducted to evaluate the accuracy of molecular diagnostic testing (qPCR) in dogs from an endemic area for canine visceral leishmaniasis (CVL) by determining which tissue type provided the highest rate of parasite DNA detection. Fifty-one symptomatic dogs were tested for CVL using serological, parasitological and molecular methods. Latent class analysis (LCA) was performed for accuracy evaluation of these methods. qPCR detected parasite DNA in 100% of these animals from at least one of the following tissues: splenic and bone marrow aspirates, lymph node and skin fragments, blood and conjunctival swabs. Using latent variable as gold standard, the qPCR achieved a sensitivity of 95.8% (CI 90.4-100) in splenic aspirate; 79.2% (CI 68-90.3) in lymph nodes; 77.3% (CI 64.5-90.1) in skin; 75% (CI 63.1-86.9) in blood; 50% (CI 30-70) in bone marrow; 37.5% (CI 24.2-50.8) in left-eye; and 29.2% (CI 16.7-41.6) in right-eye conjunctival swabs. The accuracy of qPCR using splenic aspirates was further evaluated in a random larger sample (n = 800), collected from dogs during a prevalence study. The specificity achieved by qPCR was 76.7% (CI 73.7-79.6) for splenic aspirates obtained from the greater sample. The sensitivity accomplished by this technique was 95% (CI 93.5-96.5) that was higher than those obtained for the other diagnostic tests and was similar to that observed in the smaller sampling study. This confirms that the splenic aspirate is the most effective type of tissue for detecting L. infantum infection. Additionally, we demonstrated that LCA could be used to generate a suitable gold standard for comparative CVL testing.

Show MeSH
Related in: MedlinePlus