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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 cross-sectional surveys.The total height of each bar (blue + red) represents the PCR prevalence. Countries where data were collected and their corresponding references (detailed in Table 1) are shown on the x-axis.
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pntd-0003413-g001: Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in cross-sectional surveys.The total height of each bar (blue + red) represents the PCR prevalence. Countries where data were collected and their corresponding references (detailed in Table 1) are shown on the x-axis.

Mentions: The 31 cross-sectional community surveys were conducted in 12 countries (Table 1). Twenty eight of these surveys were conducted between 1996 and 2010. Survey year was not described for the remaining three surveys (Table 1). The number of samples tested by PCR in each survey ranged from 98 to 3316 (median = 337, interquartile range: 252 to 1269). The LM prevalence of P. vivax ranged from 0.0% to 44.3% in geographically different settings, while the corresponding PCR prevalence for P. vivax in these same settings ranged from 0.2% to 59.5%. Overall across all sites, the PCR prevalence of P. vivax was significantly higher than that of LM (Wilcoxon matched-pairs signed rank test, P<0.0001, Fig. 1), i.e. PCR detected a significantly higher number of P. vivax infections than LM.


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 cross-sectional surveys.The total height of each bar (blue + red) represents the PCR prevalence. Countries where data were collected and their corresponding references (detailed in Table 1) are shown on the x-axis.
© Copyright Policy
Related In: Results  -  Collection

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

pntd-0003413-g001: Prevalence of LM (light microscopy, blue bar) and SM (sub-microscopy, red bar) P. vivax in cross-sectional surveys.The total height of each bar (blue + red) represents the PCR prevalence. Countries where data were collected and their corresponding references (detailed in Table 1) are shown on the x-axis.
Mentions: The 31 cross-sectional community surveys were conducted in 12 countries (Table 1). Twenty eight of these surveys were conducted between 1996 and 2010. Survey year was not described for the remaining three surveys (Table 1). The number of samples tested by PCR in each survey ranged from 98 to 3316 (median = 337, interquartile range: 252 to 1269). The LM prevalence of P. vivax ranged from 0.0% to 44.3% in geographically different settings, while the corresponding PCR prevalence for P. vivax in these same settings ranged from 0.2% to 59.5%. Overall across all sites, the PCR prevalence of P. vivax was significantly higher than that of LM (Wilcoxon matched-pairs signed rank test, P<0.0001, Fig. 1), i.e. PCR detected a significantly higher number of P. vivax infections than LM.

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