Do the venous blood samples replicate malaria parasite densities found in capillary blood? A field study performed in naturally-infected asymptomatic children in Cameroon

Sandeu, Maurice Marcel; Bayibéki, Albert N.; Tchioffo, Majoline T.; Abate, Luc; Gimonneau, Geoffrey; Awono-Ambene, Parfait; Nsango, Sandrine E.; Diallo, Diadier; Berry, Antoine; Texier, Gaétan; Morlais, Isabelle

doi:10.1186/s12936-017-1978-6

Cited by 22 publications

(29 citation statements)

References 29 publications

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“…ovale targets using the GFP assay. These results are in line with several previous studies that also found no differences in parasite density or diagnostic sensitivity between capillary and venous samples [10,12,13]. However, our data have shown that the GFP assays has significantly higher sensitivity for detection of Plasmodium spp.…”

Section: Discussionsupporting

confidence: 93%

“…Whereas most other studies emphasized testing of children or young teens [4,10,11,13,14], our study population was significantly older, with a median of 27 years and 25% of the tested subjects between 21 and 25 years of age. It is possible that age-related physiological differences may affect the parasite's lifecycle, its clinical presentation, and potentially even its prevalence within various compartments [23][24][25].…”

Section: Discussionmentioning

confidence: 88%

“…Several previous studies assessed parasite density and the sensitivity of malaria detection in paired capillary and venous blood samples from asymptomatic carriers and symptomatic malaria patients in sub-Saharan Africa [4,[10][11][12][13][14]. Some comparisons using standard microscopic techniques and PCR showed no difference between capillary and venous samples [10,12,13], but other showed slightly higher parasite numbers in capillary specimens [4,11,14]. Additionally, one PCR-based study documented a greater diversity of strains detected in venous blood samples [10].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of capillary and venous blood for malaria detection using two PCR based assays in febrile patients in Sierra Leone.

Łęski

Taitt

Bangura

et al. 2020

Preprint

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Background Malaria parasites infect over 200 million people and cause more than 400,000 deaths each year. Rapid and sensitive diagnostics are critical tools for clinical case management and public health control efforts. Both capillary and venous blood are currently used for malaria detection and while diagnostic technologies may not be equally sensitive with both materials the published data on this subject are scarce are not conclusive. Methods Paired samples of venous and capillary blood from 103 febrile individuals in Bo, Sierra Leone, were obtained between January and May 2019 and tested for the presence of Plasmodium parasites using two multiplexed PCR assays: the FilmArray-based Global Fever Panel (GFP) and the TaqMan-based Malaria Multiplex Sample Ready (MMSR) assay. Results We observed no significant differences in Plasmodium parasite detection between capillary and venous blood when using the MMSR assay. In GFP assays, however, markers for Plasmodium spp. and P. falciparum were detected at significantly higher numbers of venous samples (p<0.002 and p<0.05, respectively). The GFP assay was more sensitive than MMSR for Plasmodium spp. in both types of samples and overall more sensitive (taking all detected malaria markers into account) in venous samples only. Conclusions Malaria detection sensitivity may be higher for venous blood compared to capillary blood in case of certain targets when using PCR-based detection methods. The overall sensitivity of GFP assay was generally higher than MMSR but depended on the target and clinical material used.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Comparison of capillary and venous blood for malaria detection using two PCR based assays in febrile patients in Sierra Leone.

Łęski

Taitt

Bangura

et al. 2020

Preprint

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“…This phenomenon, well demonstrated for a range of helminths (15–18) and protozoic trypanosomes (14), has remained speculative for Plasmodium parasites (22). Two recent studies in Cameroonian parasite carriers that used microscopy as diagnostic tool yielded conflicting results: one observed higher P. falciparum parasite prevalence in finger prick capillary blood compared to venous blood from hospital patients (36), the other found no differences for asexual parasites or gametocytes in gametocyte carriers (37). The utility of finger prick blood to estimate parasite biomass in skin tissue is uncertain.…”

Section: Discussionmentioning

confidence: 99%

P. falciparum gametocyte density and infectivity in peripheral blood and skin tissue of naturally infected parasite carriers

Meibalan

Barry

et al. 2019

Preprint

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Transmission of Plasmodium falciparum depends on the presence of mature gametocytes that can be ingested by mosquitoes taking a bloodmeal when feeding on human skin. It has long been hypothesised that skin sequestration contributes to efficient transmission. Although skin sequestration would have major implications for our understanding of transmission biology and the suitability of mosquito feeding methodologies to measure the human infectious reservoir, it has never been formally tested. In two populations of naturally infected gametocyte carriers from Burkina Faso, we assessed transmission potential to mosquitoes and directly quantified male and female gametocytes and asexual parasites in: i) finger prick blood, ii) venous blood, iii) skin biopsies, and in pools of mosquitoes that fed iv) on venous blood or, v) directly on the skin. Whilst more mosquitoes became infected when feeding directly on the skin compared to venous blood, concentrations of gametocytes in the subdermal skin vasculature were identical to that in other blood compartments. Asexual parasite densities, gametocyte densities and sex ratios were identical in the mosquito blood meals taken directly from the skin of parasite carriers and their venous blood.We also observed sparse gametocytes in skin biopsies from legs and arms of gametocyte carriers by microscopy. Taken together, we provide conclusive evidence for the absence of significant skin sequestration of P. falciparum gametocytes. Gametocyte densities in peripheral blood are thus informative for predicting onward transmission potential to mosquitoes. Quantifying this human malaria transmission potential is of pivotal importance for the deployment and monitoring of malaria elimination initiatives.IMPORTANCEOur observations settle a long-standing question in the malaria field and close a major knowledge gap in the parasite cycle. By deploying mosquito feeding experiments and stage-specific molecular and immunofluorescence parasite detection methodologies in two populations of naturally infected parasite carriers, we conclusively reject the hypothesis of gametocyte skin sequestration. Our findings provide novel insights in parasite stage composition in human blood compartments, mosquito bloodmeals and their implications for transmission potential. We demonstrate that gametocyte levels in venous or finger prick blood can be used to predict onward transmission potential to mosquitoes. Our findings thus pave the way for methodologies to quantify the human infectious reservoir based on conventional blood sampling approaches to support the deployment and monitoring of malaria elimination efforts for maximum public health impact.

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“…Regarding the spatial distribution of mature gametocytes in the bloodstream, a handful of studies have compared their density between venous and capillary blood. A majority of them have found a higher density of gametocytes in capillary than in venous blood ((29–33) but see (34, 35)). However, comparisons of the number of gametocytes from the same blood compartment (veins or capillaries) but from different body parts has been investigated in a unique study conducted in 1952, where a 3-fold higher prevalence of gametocytes in skin capillary blood compared to thick smears prepared from finger-prick has been observed (36).…”

Section: Introductionmentioning

confidence: 99%

Opening Pandora’s Box: Distribution of Plasmodium gametocytes in bloodstream

Pigeault¹,

Isaïa²,

Yerbanga

et al. 2019

Preprint

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10Malaria, a vector borne disease caused by Plasmodium spp., remains a major global cause of 11 morbidity and mortality. Optimization of the disease control strategies requires a thorough 12 understanding of the fundamental processes underlying parasite transmission. Although the 13 number of transmissible stages of Plasmodium (gametocyte) in human blood is frequently 14 used as an indicator of human-to-mosquito transmission potential, this relationship is not 15 always clear. Important efforts have been made to develop molecular tools to fine-tune 16 gametocyte densities estimation and therefore improve the prediction of mosquito infection 17 rates, but a significant level of uncertainty around this estimate remains. Here we show with 18 both human and avian malaria system that the within-vertebrate host distribution of 19 gametocytes could explain much of this uncertainty. By comparing gametocyte densities in 20 bloodstream between different body parts, we found a difference by nearly 50% in humans 21 and by more than 15% in birds. An estimation of gametocyte density from only one blood 22 sample, as is usually the case, could therefore drastically over-or underestimated the 23 infectivity of gametocyte carriers. This might have important consequences on the 24 epidemiology of the disease since we show, using the avian malaria system, that this variation 25 influences the transmission of the parasite to the mosquito vector. In the light of our results, 26 we argue that it is essential to consider the heterogeneous distribution of gametocyte to 27 improve human diagnosis, identify infectious reservoirs and to test new malaria control 28 strategies. 29 30

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Do the venous blood samples replicate malaria parasite densities found in capillary blood? A field study performed in naturally-infected asymptomatic children in Cameroon

Cited by 22 publications

References 29 publications

Comparison of capillary and venous blood for malaria detection using two PCR based assays in febrile patients in Sierra Leone.

Comparison of capillary and venous blood for malaria detection using two PCR based assays in febrile patients in Sierra Leone.

P. falciparum gametocyte density and infectivity in peripheral blood and skin tissue of naturally infected parasite carriers

Opening Pandora’s Box: Distribution of Plasmodium gametocytes in bloodstream

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