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Systematic review of sub-microscopic P. vivax infections: prevalence and determining factors.

Cheng Q, Cunningham J, Gatton ML - PLoS Negl Trop Dis (2015)

Bottom Line: A better understanding of the epidemiology of these infections and factors contributing to their occurrence will inform effective elimination strategies.The relative proportion of SM P. vivax is significantly higher than that of the sympatric P. falciparum in these settings.Diagnostic tools with sensitivity greater than that of LM are required for detecting these infection reservoirs.

View Article: PubMed Central - PubMed

Affiliation: Drug Resistance and Diagnostics, Australian Army Malaria Institute, Enoggera, Brisbane, Australia; QIMR Berghofer Medical Research Institute, Brisbane, Australia.

ABSTRACT

Background: Sub-microscopic (SM) Plasmodium infections represent transmission reservoirs that could jeopardise malaria elimination goals. A better understanding of the epidemiology of these infections and factors contributing to their occurrence will inform effective elimination strategies. While the epidemiology of SM P. falciparum infections has been documented, that of SM P. vivax infections has not been summarised. The objective of this study is to address this deficiency.

Methodology/principal findings: A systematic search of PubMed was conducted, and results of both light microscopy (LM) and polymerase chain reaction (PCR)-based diagnostic tests for P. vivax from 44 cross-sectional surveys or screening studies of clinical malaria suspects were analysed. Analysis revealed that SM P. vivax is prevalent across different geographic areas with varying transmission intensities. On average, the prevalence of SM P. vivax in cross-sectional surveys was 10.9%, constituting 67.0% of all P. vivax infections detected by PCR. The relative proportion of SM P. vivax is significantly higher than that of the sympatric P. falciparum in these settings. A positive relationship exists between PCR and LM P. vivax prevalence, while there is a negative relationship between the proportion of SM P. vivax and the LM prevalence for P. vivax. Amongst clinical malaria suspects, however, SM P. vivax was not identified.

Conclusions/significance: SM P. vivax is prevalent across different geographic areas, particularly areas with relatively low transmission intensity. Diagnostic tools with sensitivity greater than that of LM are required for detecting these infection reservoirs. In contrast, SM P. vivax is not prevalent in clinical malaria suspects, supporting the recommended use of quality LM and rapid diagnostic tests in clinical case management. These findings enable malaria control and elimination programs to estimate the prevalence and proportion of SM P. vivax infections in their settings, and develop appropriate elimination strategies to tackle SM P. vivax to interrupt transmission.

No MeSH data available.


Related in: MedlinePlus

Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in clinical malaria suspects.Total height of the bar (blue + red) represents the PCR prevalence.
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pntd-0003413-g008: Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in clinical malaria suspects.Total height of the bar (blue + red) represents the PCR prevalence.

Mentions: In 13 surveys of clinical malaria suspects conducted in different transmission settings (1997–2010), the prevalence of P. vivax infections determined by LM varied widely from 0.7% to 86.0% of the patients. Although PCR detected more P. vivax infections in some studies, overall it did not have a significantly higher prevalence than LM in fever patients (Wilcoxon matched-pairs signed rank test, P = 0.278, Fig. 8). In these same surveys, the LM P. falciparum prevalence rates ranged from 1.0% to 54.2% while PCR prevalence rates ranged from 1.0% to 46.9%. Similar to P. vivax, PCR did not detect a significantly higher number of P. falciparum infections than LM in these patients (Wilcoxon matched-pairs signed rank test, P = 0.123, Fig. 9). This suggests that amongst symptomatic patient populations SM P. vivax and P. falciparum are not prevalent.


Systematic review of sub-microscopic P. vivax infections: prevalence and determining factors.

Cheng Q, Cunningham J, Gatton ML - PLoS Negl Trop Dis (2015)

Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in clinical malaria suspects.Total height of the bar (blue + red) represents the PCR prevalence.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4288718&req=5

pntd-0003413-g008: Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in clinical malaria suspects.Total height of the bar (blue + red) represents the PCR prevalence.
Mentions: In 13 surveys of clinical malaria suspects conducted in different transmission settings (1997–2010), the prevalence of P. vivax infections determined by LM varied widely from 0.7% to 86.0% of the patients. Although PCR detected more P. vivax infections in some studies, overall it did not have a significantly higher prevalence than LM in fever patients (Wilcoxon matched-pairs signed rank test, P = 0.278, Fig. 8). In these same surveys, the LM P. falciparum prevalence rates ranged from 1.0% to 54.2% while PCR prevalence rates ranged from 1.0% to 46.9%. Similar to P. vivax, PCR did not detect a significantly higher number of P. falciparum infections than LM in these patients (Wilcoxon matched-pairs signed rank test, P = 0.123, Fig. 9). This suggests that amongst symptomatic patient populations SM P. vivax and P. falciparum are not prevalent.

Bottom Line: A better understanding of the epidemiology of these infections and factors contributing to their occurrence will inform effective elimination strategies.The relative proportion of SM P. vivax is significantly higher than that of the sympatric P. falciparum in these settings.Diagnostic tools with sensitivity greater than that of LM are required for detecting these infection reservoirs.

View Article: PubMed Central - PubMed

Affiliation: Drug Resistance and Diagnostics, Australian Army Malaria Institute, Enoggera, Brisbane, Australia; QIMR Berghofer Medical Research Institute, Brisbane, Australia.

ABSTRACT

Background: Sub-microscopic (SM) Plasmodium infections represent transmission reservoirs that could jeopardise malaria elimination goals. A better understanding of the epidemiology of these infections and factors contributing to their occurrence will inform effective elimination strategies. While the epidemiology of SM P. falciparum infections has been documented, that of SM P. vivax infections has not been summarised. The objective of this study is to address this deficiency.

Methodology/principal findings: A systematic search of PubMed was conducted, and results of both light microscopy (LM) and polymerase chain reaction (PCR)-based diagnostic tests for P. vivax from 44 cross-sectional surveys or screening studies of clinical malaria suspects were analysed. Analysis revealed that SM P. vivax is prevalent across different geographic areas with varying transmission intensities. On average, the prevalence of SM P. vivax in cross-sectional surveys was 10.9%, constituting 67.0% of all P. vivax infections detected by PCR. The relative proportion of SM P. vivax is significantly higher than that of the sympatric P. falciparum in these settings. A positive relationship exists between PCR and LM P. vivax prevalence, while there is a negative relationship between the proportion of SM P. vivax and the LM prevalence for P. vivax. Amongst clinical malaria suspects, however, SM P. vivax was not identified.

Conclusions/significance: SM P. vivax is prevalent across different geographic areas, particularly areas with relatively low transmission intensity. Diagnostic tools with sensitivity greater than that of LM are required for detecting these infection reservoirs. In contrast, SM P. vivax is not prevalent in clinical malaria suspects, supporting the recommended use of quality LM and rapid diagnostic tests in clinical case management. These findings enable malaria control and elimination programs to estimate the prevalence and proportion of SM P. vivax infections in their settings, and develop appropriate elimination strategies to tackle SM P. vivax to interrupt transmission.

No MeSH data available.


Related in: MedlinePlus