Seasonal changes in the Plasmodium falciparum population in individuals and their relationship to clinical malaria: a longitudinal study in a Sudanese village

Parasitology ◽  
1998 ◽  
Vol 116 (6) ◽  
pp. 501-510 ◽  
Author(s):  
C. ROPER ◽  
W. RICHARDSON ◽  
I. M. ELHASSAN ◽  
H. GIHA ◽  
L. HVIID ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Malaria ◽  
Dry Season ◽  
Malaria Episode ◽  
Allelic Polymorphism ◽  
Cross Sectional ◽  
Increased Risk ◽  
Risk Of Disease ◽  
Polymerase Chain ◽  
Malaria Episodes

Residents of Daraweesh village in Sudan were monitored for Plasmodium falciparum infection and malaria morbidity in 3 malaria seasons from 1993 to 1996. Malaria parasites were detected microscopically and by polymerase chain reaction (PCR) in a series of cross-sectional surveys. PCR revealed submicroscopical infections during the dry season, particularly among individuals who had recovered from a malaria episode following successful drug treatment. Clinical and subclinical infections were contrasted by assaying for allelic polymorphism at 2 gene loci, MSP-1 and GLURP and 2 hypotheses examined with reference to these data: that clinical malaria is associated with infection with novel parasite genotypes not previously detected in that host, or alternatively, that clinical malaria episodes are associated with an increased number of clones in an infection. We detected more mixed infections among clinical isolates, but people carrying parasites during the dry season were not found to have an increased risk of disease in the following malaria season. There was a clear association of disease with the appearance of novel parasite genotypes.

scholarly journals Chronic Plasmodium falciparum infections in an area of low intensity malaria transmission in the Sudan

Parasitology ◽  
2000 ◽  
Vol 120 (5) ◽  
pp. 447-456 ◽  
Author(s):  
A. A. HAMAD ◽  
I. M. EL HASSAN ◽  
A. A. EL KHALIFA ◽  
G. I. AHMED ◽  
S. A. ABDELRAHIM ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Marker Gene ◽  
Allelic Polymorphism ◽  
Chain Reaction ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Polymerase Chain ◽  
The Village ◽  
Eastern Sudan

Chronic Plasmodium falciparum malaria infections in a Sudanese village, in an area of seasonal and unstable malaria transmission, were monitored and genetically characterized to study the influence of persistent infection on the immunology and epidemiology of low endemicity malaria. During the October–December malaria season of 1996, 51 individuals out of a population of 420 had confirmed and treated P. falciparum malaria in the village of Daraweesh in eastern Sudan. In a cross-sectional survey carried out in December 1996, an additional 6 individuals were found to harbour a microscopically negative but polymerase chain reaction (PCR)-positive P. falciparum infection. On 1 January 1997, a cohort of 43 individuals aged from 9 to 53, recruited from this group of recently malaria-infected individuals agreed to donate fortnightly blood samples for the next 9 months, the first 6 of which constitute the long Sudanese dry season when transmission falls to undetectable levels. Each blood sample was tested for the presence of persistent malaria infection by microscopy and PCR. Parasite-positive samples were genotyped using PCR assays that detect allelic polymorphism at the MSP-1, MSP-2 and GLURP marker gene loci. Of 43 individuals 16 were found to maintain chronic P. falciparum infections which were continuously genetically characterized.

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 Antibodies to Peptides in Semiconserved Domains of RIFINs and STEVORs Correlate with Malaria Exposure

mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Albert E. Zhou ◽  
Andrea A. Berry ◽  
Jason A. Bailey ◽  
Andrew Pike ◽  
Antoine Dara ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Severe Malaria ◽  
Surface Antigen ◽  
Immune Evasion ◽  
Clinical Malaria ◽  
Malaria Episode ◽  
Natural Immunity ◽  
Content Type ◽  
Variant Surface Antigen ◽  
Malaria Exposure

ABSTRACT The repetitive interspersed family (RIFIN) and the subtelomeric variable open reading frame (STEVOR) family represent two of three major Plasmodium falciparum variant surface antigen families involved in malaria pathogenesis and immune evasion and are potential targets in the development of natural immunity. Protein and peptide microarrays populated with RIFINs and STEVORs associated with severe malaria vulnerability in Malian children were probed with adult and pediatric sera to identify epitopes that reflect malaria exposure. Adult sera recognized and reacted with greater intensity to all STEVOR proteins than pediatric sera did. Serorecognition of and seroreactivity to peptides within the semiconserved domain of STEVORs increased with age and seasonal malaria exposure, while serorecognition and seroreactivity increased for the semiconserved and second hypervariable domains of RIFINs only with age. Serologic responses to RIFIN and STEVOR peptides within the semiconserved domains may play a role in natural immunity to severe malaria. IMPORTANCE Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs.

scholarly journals Effect of Seasonality and Ecological Factors on the Prevalence of the Four Malaria Parasite Species in Northern Mali

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Ousmane A. Koita ◽  
Lansana Sangaré ◽  
Hammadoun A. Sango ◽  
Sounkalo Dao ◽  
Naffet Keita ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Parasite Species ◽  
Ecological Factors ◽  
Seasonal Fluctuation ◽  
Parasite Prevalence ◽  
Dry Season ◽  
Sahara Desert ◽  
Cross Sectional ◽  
Hot Dry Season

Background. We performed 2 cross-sectional studies in Ménaka in the Northeastern Mali across 9 sites in different ecological settings: 4 sites have permanent ponds, 4 without ponds, and one (City of Ménaka) has a semipermanent pond. We enrolled 1328 subjects in May 2004 (hot dry season) and 1422 in February 2005 (cold dry season) after the rainy season.Objective.To examine the seasonality of malaria parasite prevalence in this dry northern part of Mali at the edge of the Sahara desert.Results. Slide prevalence was lower in hot dry than cold dry season (4.94 versus 6.85%,P=0.025). Gametocyte rate increased to 0.91% in February. Four species were identified.Plasmodium falciparumwas most prevalent (74.13 and 63.72%).P. malariaeincreased from 9.38% to 22.54% in February. In contrast, prevalence ofP. vivaxwas higher (10.31%) without seasonal variation. Smear positivity was associated with splenomegaly (P=0.007). Malaria remained stable in the villages with ponds (P=0.221); in contrast, prevalence varied between the 2 seasons in the villages without ponds (P=0.004).Conclusion. Malaria was mesoendemic; 4 species circulates with a seasonal fluctuation forPlasmodium falciparum.

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 PO 8458 POLYMORPHISM OF THE PLASMODIUM FALCIPARUM MSP-2 GENE ASSOCIATED WITH PLACENTAL MALARIA AT THE BORGOU-ALIBORI DEPARTMENTAL HOSPITAL

2019 ◽  
Vol 4 (Suppl 3) ◽  
pp. A40.1-A40
Author(s):  
Dossou Akpéyédjé ◽  
Saadou Issifou
Keyword(s):  
Plasmodium Falciparum ◽  
Univariate Analysis ◽  
Placental Malaria ◽  
Cross Sectional Study ◽  
Sub Saharan Africa ◽  
Allelic Polymorphism ◽  
Cross Sectional ◽  
Major Health Problem ◽  
Prenatal Consultation ◽  
Sub Saharan

BackgroundIn sub-Saharan Africa, malaria during pregnancy is a major health problem because it poses significant risks for the pregnant woman and the foetus. The sequestration of Plasmodium falciparum-infected erythrocytes in the placenta has consequences for the mother and the foetus. This study aimed to evaluate the allelic polymorphism of the Plasmodium falciparum MSP-2 gene related to the consequences of placental malaria.MethodsIt was a cross-sectional study conducted over two periods lasting six months in 2016 and 2017. The maternity center of the Hospital of Borgou-Alibori in Benin served as a framework for the study. From the 98 parturients included, placental blood samples were taken and then genotyped.ResultsUsing the MSP-2 gene as marker, the prevalence was 17, 34%. The MSP-2 gene was polymorphic with 9 distinct allelic types for both 3D7 and FC27 families (150 bp; 200 bp; 250 bp; 275 bp; 300 bp; 350 bp; 400 bp; 450 bp and 500 bp). The FC27 allelic family was predominant over the 3D7 family with 56, 25% and 43, 75% respectively. The 300 bp allelic type (50%) was predominant in the FC27 family while the 400 bp type was predominant in 3D7 family (35, 71%). 9 women had polyclonality (52,94%). The multiplicity of infection (MOI) was 1, 88. The number of strains ranged 1 to 4 in infected women. In univariate analysis there was no significant relationship between MSP-2 gene polymorphism and maternofoetal consequences. The absence of „prenatal consultation (p=0.0270), non-taking of IPTp/SP (p=0.0060), the occurrence of malaria in the third trimester (p=0,0364) and moderate maternal anaemia (p=0.0277) were associated with the polymorphism of MSP-2 gene. The MOI was significantly associated with parasite density of infected women.ConclusionPlasmodium falciparum MSP-2 gene was polymorphic in infected women at Parakou. Several factors related to pregnancy monitoring were associated with this genetic diversity. It is therefore essential to ensure correct follow-up of pregnancies.

scholarly journals Transmission and Age Impact the Risk of Developing Febrile Malaria in Children with Asymptomatic Plasmodium falciparum Parasitemia

2018 ◽  
Vol 219 (6) ◽  
pp. 936-944 ◽  
Author(s):  
Kevin Wamae ◽  
Juliana Wambua ◽  
George Nyangweso ◽  
Gabriel Mwambingu ◽  
Faith Osier ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Febrile Illness ◽  
Transmission Intensity ◽  
Older Children ◽  
Cross Sectional ◽  
Increased Risk ◽  
Kenyan Coast ◽  
Lower Transmission ◽  
Febrile Episodes

Abstract Background Plasmodium falciparum infections lead to febrile illness unless the host has sufficient immunity, in which case infection may cause no immediate symptoms (ie, “asymptomatic parasitemia”). Previous studies are conflicting on the role of asymptomatic parasitemia in determining the risk of developing febrile malaria. Methods We monitored 2513 children (living in Kilifi, Kenyan Coast) by blood smears in 17 cross-sectional surveys to identify asymptomatic parasitemia and used active surveillance over 11325 child-years of follow-up to detect febrile malaria. We evaluated the interaction between transmission intensity, age, and asymptomatic parasitemia in determining the risk of developing febrile malaria. Results In the moderate and high transmission intensity settings, asymptomatic parasitemia was associated with a reduced risk of febrile malaria in older children (> 3 years), while in the lower transmission setting, asymptomatic parasitemia was associated with an increased risk of febrile malaria in children of all ages. Additionally, the risk associated with asymptomatic parasitemia was limited to the first 90 days of follow-up. Conclusions Asymptomatic parasitemia is modified by transmission intensity and age, altering the risk of developing febrile episodes and suggesting that host immunity plays a prominent role in mediating this process.

scholarly journals Interferon-γ and Interleukin-10 Responses during Clinical Malaria Episodes in Infants Aged 0–2 Years Prenatally Exposed to Plasmodium falciparum: Tanzanian Birth Cohort

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Boniphace Sylvester ◽  
Dinah B. Gasarasi ◽  
Said Aboud ◽  
Donath Tarimo ◽  
Siriel Masawe ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Prenatal Exposure ◽  
Geometric Mean ◽  
Placental Malaria ◽  
Clinical Malaria ◽  
Interleukin 10 ◽  
Interferon Γ ◽  
Enzyme Linked Immunosorbent Assay ◽  
Prenatally Exposed ◽  
Malaria Episodes

Background. Infants born to mothers with placental malaria are prenatally exposed to Plasmodium falciparum antigens. However, the effect of that exposure to subsequent immune responses has not been fully elucidated. This study aimed at determining the effect of prenatal exposure to P. falciparum on Interleukin-10 and Interferon-γ responses during clinical malaria episodes in the first 24 months of life. Methods. This prospective cohort study involved 215 infants aged 0-2 years born to mothers with or without placental malaria. Enzyme-linked immunosorbent assay (ELISA) was used to determine levels of IL-10 and IFN-γ in infants and detect IgM in cord blood. Data were analyzed using SPSS version 20. Findings. Geometric mean for IFN-γ in exposed infants was 557.9 pg/ml (95% CI: 511.6-604.1) and in unexposed infants it was 634.4 pg/ml (95% CI: 618.2-668.5) (P=0.02). Mean IL-10 was 22.4 pg/ml (95% CI: 19.4-28.4) and 15.1 pg/ml (95%CI: 12.4-17.6), respectively (P=0.01). Conclusions. Prenatal exposure to P. falciparum antigens significantly affects IL-10 and IFN-γ responses during clinical malaria episodes in the first two years of life.

scholarly journals Novel Plasmodium falciparum clones and rising clone multiplicities are associated with the increase in malaria morbidity in Ghanaian children during the transition into the high transmission season

Parasitology ◽  
2001 ◽  
Vol 123 (2) ◽  
pp. 113-123 ◽  
Author(s):  
A. OFOSU-OKYERE ◽  
M. J. MACKINNON ◽  
M. P. K. SOWA ◽  
K. A. KORAM ◽  
F. NKRUMAH ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Disease Incidence ◽  
Clinical Malaria ◽  
Malaria Episode ◽  
Transmission Season ◽  
Rural Town ◽  
Symptomatic Malaria ◽  
Malaria Transmission Season ◽  
Minimum Number ◽  
Ghanaian Child

A survey of Plasmodium falciparum infection and clone multiplicity in Ghanaian children was carried out to study the effect of the onset of the malaria transmission season on disease incidence. Fortnightly blood samples were collected from 40 children living in the rural town of Dodowa, between February and August 1998. P. falciparum parasite densities were calculated and PCR genotyping was carried out using the polymorphic MSP-1 and MSP-2 genes as target loci for the estimation of the number of parasite clones in each sample. The average clone number was estimated using maximum likelihood techniques and the minimum number of clones per patient was analysed for the effects of age, sex, season, minimum number of clones per child, level of parasitaemia and parasite genotype. The statistical analysis indicated that the more clones a child carried, the more likely they were to have a clinical malaria episode. This was true after adjusting for age and season effects and for the measured circulating parasitaemia. The probability of clinical disease also increased if the MSP-1 MAD 20 and the MSP-2 FC 27 alleles were present. This longitudinal analysis thus indicates that the probability of a Ghanaian child having a symptomatic malaria episode is positively associated with both increasing numbers and novel types of P. falciparum clones.

scholarly journals Detecting Plasmodium falciparum in community surveys: a comparison of Paracheck Pf® Test and ICT Malaria Pf® Cassette Test to polymerase chain reaction in Mutasa District, Zimbabwe

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Nobert Mudare ◽  
Zvifadzo Matsena-Zingoni ◽  
Aramu Makuwaza ◽  
Edmore Mamini ◽  
Shungu S. Munyati ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Plasmodium Falciparum ◽  
Mitochondrial Gene ◽  
Dried Blood Spots ◽  
Diagnostic Methods ◽  
Chain Reaction ◽  
Cross Sectional ◽  
Predictive Values ◽  
Polymerase Chain ◽  
Pcr Targeting

Abstract Background Microscopy and rapid diagnostic tests (RDTs) are the main techniques used to diagnose malaria. While microscopy is considered the gold standard, RDTs have established popularity as they allow for rapid diagnosis with minimal technical skills. This study aimed to compare the diagnostic performance of two Plasmodium falciparum histidine-rich protein 2 (PfHRP2)-based RDTs (Paracheck Pf® Test (Paracheck) and Malaria Pf™ ICT (ICT)) to polymerase chain reaction (PCR) in a community survey. Methods A cross-sectional study was conducted between October 2012 and December 2014 in Mutasa District, Manicaland Province, eastern Zimbabwe. Households were randomly selected using satellite imagery, and 224 households were visited. Residents present in the household on the date of the visit were recruited for the study. Participants of all age groups from the selected households were screened with Paracheck and ICT RDTs in parallel. Dried blood spots (DBS) and thin and thick smears were collected. Parasite DNA extracted from the DBS was subjected to nested PCR targeting the Plasmodium cytochrome b mitochondrial gene. Data analysis was performed using the Cohen’s Kappa test to determine the interrater agreement and the sensitivity and specificity of the diagnostic test were reported. Results Results from a total of 702 participants were analysed. Most were females, 397 (57%), and the median age of participants was 21 years with an interquartile range of 9–39 years. Of those who were screened, 8 (1.1%), 35 (5.0%), and 21 (2.9%) were malaria parasite positive by microscopy, RDT and PCR, respectively. Paracheck and ICT RDTs had a 100% agreement. Comparing RDT and PCR results, 34 participants (4.8%) had discordant results. Most of the discordant cases were RDT positive but PCR negative (n = 24). Half of those RDT positive, but PCR negative individuals reported anti-malarials to use in the past month, which is significantly higher than reported anti-malarial drug use in the population (p < 0.001). The participant was febrile on the day of the visit, but relying on PfHRP2-based RDT would miss this case. Among the diagnostic methods evaluated, with reference to PCR, the sensitivity was higher with the RDT (52.4%) while specificity was higher with the microscopy (99.9%). The positive predictive value (PPV) was higher with the microscopy (87.5%), while the negative predictive values were similar for both microscopy and RDTs (98%). Overall, a strong correlated agreement with PCR was observed for the microscopy (97.9%) and the RDTs (95.2%). Conclusions Paracheck and ICT RDTs showed 100% agreement and can be used interchangeably. As malaria transmission declines and Zimbabwe aims to reach malaria elimination, management of infected individuals with low parasitaemia as well as non-P. falciparum infection can be critical.

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