Plasmodium falciparum clinical malaria in Dielmo, a holoendemic area in Senegal: no influence of acquired immunity on initial symptomatology and severity of malaria attacks.

1999 ◽  
Vol 60 (3) ◽  
pp. 410-420 ◽  
Author(s):  
C Rogier ◽  
B Cissé ◽  
A B Ly ◽  
J F Trape ◽  
A Tall
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Malaria ◽  
Acquired Immunity

scholarly journals 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity

2021 ◽  
Vol 6 ◽  
pp. 79
Author(s):  
John W.G. Addy ◽  
Yaw Bediako ◽  
Francis M. Ndungu ◽  
John Joseph Valetta ◽  
Adam J. Reid ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Symptoms ◽  
Clinical Malaria ◽  
Multiple Infections ◽  
Acquired Immunity ◽  
Large Variability ◽  
Antibody Titres ◽  
Using Data ◽  
Malaria Episodes

Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.

scholarly journals 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity

2021 ◽  
Vol 6 ◽  
pp. 79
Author(s):  
John W.G. Addy ◽  
Yaw Bediako ◽  
Francis M. Ndungu ◽  
John Joseph Valetta ◽  
Adam J. Reid ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Symptoms ◽  
Clinical Malaria ◽  
Multiple Infections ◽  
Acquired Immunity ◽  
Large Variability ◽  
Antibody Titres ◽  
Using Data ◽  
Malaria Episodes

Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

scholarly journals Changes in Antigen-Specific Cytokine and Chemokine Responses to Plasmodium falciparum Antigens in a Highland Area of Kenya after a Prolonged Absence of Malaria Exposure

2014 ◽  
Vol 82 (9) ◽  
pp. 3775-3782 ◽  
Author(s):  
Lyticia A. Ochola ◽  
Cyrus Ayieko ◽  
Lily Kisia ◽  
Ng'wena G. Magak ◽  
Estela Shabani ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Severe Disease ◽  
Clinical Malaria ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Highland Area ◽  
Cytokine Responses ◽  
Increased Risk ◽  
Tnf Α ◽  
Ifn Γ

ABSTRACTIndividuals naturally exposed toPlasmodium falciparumlose clinical immunity after a prolonged lack of exposure.P. falciparumantigen-specific cytokine responses have been associated with protection from clinical malaria, but the longevity ofP. falciparumantigen-specific cytokine responses in the absence of exposure is not well characterized. A highland area of Kenya with low and unstable malaria transmission provided an opportunity to study this question. The levels of antigen-specific cytokines and chemokines associated in previous studies with protection from clinical malaria (gamma interferon [IFN-γ], interleukin-10 [IL-10], and tumor necrosis factor alpha [TNF-α]), with increased risk of clinical malaria (IL-6), or with pathogenesis of severe disease in malaria (IL-5 and RANTES) were assessed by cytometric bead assay in April 2008, October 2008, and April 2009 in 100 children and adults. During the 1-year study period, none had an episode of clinicalP. falciparummalaria. Two patterns of cytokine responses emerged, with some variation by antigen: a decrease at 6 months (IFN-γ and IL-5) or at both 6 and 12 months (IL-10 and TNF-α) or no change over time (IL-6 and RANTES). These findings document thatP. falciparumantigen-specific cytokine responses associated in prior studies with protection from malaria (IFN-γ, TNF-α, and IL-10) decrease significantly in the absence ofP. falciparumexposure, whereas those associated with increased risk of malaria (IL-6) do not. The study findings provide a strong rationale for future studies of antigen-specific IFN-γ, TNF-α, and IL-10 responses as biomarkers of increased population-level susceptibility to malaria after prolonged lack ofP. falciparumexposure.

scholarly journals Treatment of Chronic Asymptomatic Plasmodium falciparum Infection Does Not Increase the Risk of Clinical Malaria Upon Reinfection

2016 ◽  
Vol 64 (5) ◽  
pp. 645-653 ◽  
Author(s):  
Silvia Portugal ◽  
Tuan M. Tran ◽  
Aissata Ongoiba ◽  
Aboudramane Bathily ◽  
Shanping Li ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Malaria ◽  
Falciparum Infection ◽  
Plasmodium Falciparum Infection

scholarly journals IgM in human immunity to Plasmodium falciparum malaria

2019 ◽  
Vol 5 (9) ◽  
pp. eaax4489 ◽  
Author(s):  
M. J. Boyle ◽  
J. A. Chan ◽  
I. Handayuni ◽  
L. Reiling ◽  
G. Feng ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Blood Cells ◽  
Plasmodium Falciparum Malaria ◽  
Clinical Malaria ◽  
Blood Stage ◽  
Dependent Manner ◽  
Human Immunity ◽  
Lifetime Exposure ◽  
Blood Stage Malaria ◽  
Reduced Risk

Most studies on human immunity to malaria have focused on the roles of immunoglobulin G (IgG), whereas the roles of IgM remain undefined. Analyzing multiple human cohorts to assess the dynamics of malaria-specific IgM during experimentally induced and naturally acquired malaria, we identified IgM activity against blood-stage parasites. We found that merozoite-specific IgM appears rapidly in Plasmodium falciparum infection and is prominent during malaria in children and adults with lifetime exposure, together with IgG. Unexpectedly, IgM persisted for extended periods of time; we found no difference in decay of merozoite-specific IgM over time compared to that of IgG. IgM blocked merozoite invasion of red blood cells in a complement-dependent manner. IgM was also associated with significantly reduced risk of clinical malaria in a longitudinal cohort of children. These findings suggest that merozoite-specific IgM is an important functional and long-lived antibody response targeting blood-stage malaria parasites that contributes to malaria immunity.

scholarly journals Antibodies to Plasmodium falciparum Erythrocyte-binding Antigen-175 are Associated With Protection From Clinical Malaria

2011 ◽  
Vol 30 (12) ◽  
pp. 1037-1042 ◽  
Author(s):  
Matthew B. McCarra ◽  
George Ayodo ◽  
Peter O. Sumba ◽  
James W. Kazura ◽  
Ann M. Moormann ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Malaria ◽  
Erythrocyte Binding
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