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Quantitative PCR in epidemiology for early detection of visceral leishmaniasis cases in India.

Sudarshan M, Singh T, Singh AK, Chourasia A, Singh B, Wilson ME, Chakravarty J, Sundar S - PLoS Negl Trop Dis (2014)

Bottom Line: Ten subjects had developed to symptomatic VL after 12 month of their follow up examination, of which eight were initially positive according to qPCR and among these, five had high parasite load.Thus, qPCR can help us to detect significant early parasitaemia, thereby assisting us in recognition of potential progressors to clinical disease.This test could facilitate early intervention, decreased morbidity and mortality, and possibly interruption of disease transmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.

ABSTRACT

Introduction: Studies employing serological, DTH or conventional PCR techniques suggest a vast proportion of Leishmania infected individuals living in regions endemic for Visceral Leishmaniasis (VL) remain asymptomatic. This study was designed to assess whether quantitative PCR (qPCR) can be used for detection of asymptomatic or early Leishmania donovani infection and as a predictor of progression to symptomatic disease.

Methods: The study included 1469 healthy individuals living in endemic region (EHC) including both serology-positive and -negative subjects. TaqMan based qPCR assay was done on peripheral blood of each subject using kDNA specific primers and probes.

Results: A large proportion of EHC 511/1469 (34.78%) showed qPCR positivity and 56 (3.81% of 1469 subjects) had more than 1 calculated parasite genome/ml of blood. However, the number of individuals with parasite load above 5 genomes/ml was only 20 (1.36% of 1469). There was poor agreement between serological testing and qPCR (k = 0.1303), and 42.89% and 31.83% EHC were qPCR positive in seropositive and seronegative groups, respectively. Ten subjects had developed to symptomatic VL after 12 month of their follow up examination, of which eight were initially positive according to qPCR and among these, five had high parasite load.

Discussion: Thus, qPCR can help us to detect significant early parasitaemia, thereby assisting us in recognition of potential progressors to clinical disease. This test could facilitate early intervention, decreased morbidity and mortality, and possibly interruption of disease transmission.

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Related in: MedlinePlus

Bar graph to show Leishmania detected by qPCR in different group of EHC on the basis of their serological status (QP-qPCR positive, QN-qPCR negative, SP-sero positive, SN-sero negative).
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pntd-0003366-g002: Bar graph to show Leishmania detected by qPCR in different group of EHC on the basis of their serological status (QP-qPCR positive, QN-qPCR negative, SP-sero positive, SN-sero negative).

Mentions: Among a total of 1469 healthy individuals living in the endemic villages, 511 (34.78%) were positive by qPCR for amplification of any parasite DNA (CT less than 39). 171/401 (42.8%) were from seropositive group and the remaining 340/1068 (31.6%) were seronegative (Fig. 2, Table 2). The median value of parasite genomes/ml of blood was less than one and found to be 0.11 and 0.15 in seropositive and seronegative group respectively. Ten individuals who were initially belong to both seropositive and seronegative category progressed to symptomatic VL by the time of the follow up. Six (60%) were both qPCR and serology positive, two (20%) were qPCR positive but seronegative, whereas two (20%) were both qPCR and serologically negative (Table 3). Among these qPCR positive progressor five of the progessors had parasitemia levels equal to or more than the threshold value for ocuurence of symptomatic VL due to L.donovani.


Quantitative PCR in epidemiology for early detection of visceral leishmaniasis cases in India.

Sudarshan M, Singh T, Singh AK, Chourasia A, Singh B, Wilson ME, Chakravarty J, Sundar S - PLoS Negl Trop Dis (2014)

Bar graph to show Leishmania detected by qPCR in different group of EHC on the basis of their serological status (QP-qPCR positive, QN-qPCR negative, SP-sero positive, SN-sero negative).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4263468&req=5

pntd-0003366-g002: Bar graph to show Leishmania detected by qPCR in different group of EHC on the basis of their serological status (QP-qPCR positive, QN-qPCR negative, SP-sero positive, SN-sero negative).
Mentions: Among a total of 1469 healthy individuals living in the endemic villages, 511 (34.78%) were positive by qPCR for amplification of any parasite DNA (CT less than 39). 171/401 (42.8%) were from seropositive group and the remaining 340/1068 (31.6%) were seronegative (Fig. 2, Table 2). The median value of parasite genomes/ml of blood was less than one and found to be 0.11 and 0.15 in seropositive and seronegative group respectively. Ten individuals who were initially belong to both seropositive and seronegative category progressed to symptomatic VL by the time of the follow up. Six (60%) were both qPCR and serology positive, two (20%) were qPCR positive but seronegative, whereas two (20%) were both qPCR and serologically negative (Table 3). Among these qPCR positive progressor five of the progessors had parasitemia levels equal to or more than the threshold value for ocuurence of symptomatic VL due to L.donovani.

Bottom Line: Ten subjects had developed to symptomatic VL after 12 month of their follow up examination, of which eight were initially positive according to qPCR and among these, five had high parasite load.Thus, qPCR can help us to detect significant early parasitaemia, thereby assisting us in recognition of potential progressors to clinical disease.This test could facilitate early intervention, decreased morbidity and mortality, and possibly interruption of disease transmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.

ABSTRACT

Introduction: Studies employing serological, DTH or conventional PCR techniques suggest a vast proportion of Leishmania infected individuals living in regions endemic for Visceral Leishmaniasis (VL) remain asymptomatic. This study was designed to assess whether quantitative PCR (qPCR) can be used for detection of asymptomatic or early Leishmania donovani infection and as a predictor of progression to symptomatic disease.

Methods: The study included 1469 healthy individuals living in endemic region (EHC) including both serology-positive and -negative subjects. TaqMan based qPCR assay was done on peripheral blood of each subject using kDNA specific primers and probes.

Results: A large proportion of EHC 511/1469 (34.78%) showed qPCR positivity and 56 (3.81% of 1469 subjects) had more than 1 calculated parasite genome/ml of blood. However, the number of individuals with parasite load above 5 genomes/ml was only 20 (1.36% of 1469). There was poor agreement between serological testing and qPCR (k = 0.1303), and 42.89% and 31.83% EHC were qPCR positive in seropositive and seronegative groups, respectively. Ten subjects had developed to symptomatic VL after 12 month of their follow up examination, of which eight were initially positive according to qPCR and among these, five had high parasite load.

Discussion: Thus, qPCR can help us to detect significant early parasitaemia, thereby assisting us in recognition of potential progressors to clinical disease. This test could facilitate early intervention, decreased morbidity and mortality, and possibly interruption of disease transmission.

Show MeSH
Related in: MedlinePlus