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Asymptomatic carriage of Plasmodium falciparum by individuals with variant blood groups and haemoglobin genotypes in southern Ghana.

ABSTRACT: BACKGROUND:The ABO and the Rhesus blood group systems, as well as various abnormal haemoglobin (Hb) variants (haemoglobinopathies) are known to influence malaria parasite carriage and disease severity in individuals living in malaria endemic areas. This study identified the blood group and Hb variant distribution and Plasmodium falciparum infection status of afebrile individuals living in southern Ghana. METHODS:Afebrile participants were recruited from Obom (358) in the Greater Accra Region and Ewim (100) and Simiw (329) in the Central Region of Ghana. Venous blood (1 ml) was collected into EDTA vacutainer tubes. Three 20 ?l drops of blood were used for blood group analysis using the tile method. Another 500 ?l aliquot was used for the qualitative sickling test using sodium metabisulphite and haemoglobin electrophoresis. Genomic DNA was extracted from 100 ?l of whole blood and used in P. falciparum species-specific PCR. RESULTS:The most abundant blood group and abnormal haemoglobin variant in both sites was blood group O?+?(47.4%) and HbAS (15.8%). A total of 13 (1.7%) of the participants had full haemoglobinopathies (SS, SC and CC), whilst 196 (25.4%) were carriers (AS and AC). Although there was a significantly higher prevalence of sickling positive participants from the Central Region, genotyping identified a similar prevalence of each of the abnormal haemoglobin genes in both sites. Asymptomatic parasite carriage estimated by PCR was 40.9% in the Central Region and 41.8% in the Greater Accra Region. CONCLUSIONS:Asymptomatic carriage of P. falciparum parasite in the study population was not associated with any particular blood group variant or haemoglobin genotype.

SUBMITTER: Acquah FK

PROVIDER: S-EPMC7310487 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Asymptomatic carriage of Plasmodium falciparum by individuals with variant blood groups and haemoglobin genotypes in southern Ghana.

Acquah Festus K FK Donu Dickson D Bredu Dorcas D Eyia-Ampah Sophia S Amponsah Jones A JA Quartey Joseph J Obboh Evans K EK Mawuli Bernice A BA Amoah Linda E LE

Malaria journal 20200623 1

<h4>Background</h4>The ABO and the Rhesus blood group systems, as well as various abnormal haemoglobin (Hb) variants (haemoglobinopathies) are known to influence malaria parasite carriage and disease severity in individuals living in malaria endemic areas. This study identified the blood group and Hb variant distribution and Plasmodium falciparum infection status of afebrile individuals living in southern Ghana.<h4>Methods</h4>Afebrile participants were recruited from Obom (358) in the Greater A ...[more]

PMID: 32576186

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Project description:BackgroundAsymptomatic malaria infections can serve as potential reservoirs for malaria transmission. The density of parasites contained in these infections range from microscopic to submicroscopic densities, making the accurate detection of asymptomatic parasite carriage highly dependent on the sensitivity of the tools used for the diagnosis. This study sought to evaluate the sensitivities of a variety of molecular and serological diagnostic tools at determining the prevalence of asymptomatic Plasmodium falciparum parasite infections in two communities with varying malaria parasite prevalence.MethodsWhole blood was collected from 194 afebrile participants aged between 6 and 70 years old living in a high (Obom) and a low (Asutsuare) malaria transmission setting of Ghana. Thick and thin blood smears, HRP2 based malaria rapid diagnostic test (RDT) and filter paper dried blood spots (DBS) were prepared from each blood sample. Genomic DNA was extracted from the remaining blood and used in Plasmodium specific photo-induced electron transfer polymerase chain reaction (PET-PCR) and Nested PCR, whilst the HRP2 antigen content of the DBS was estimated using a bead immunoassay. A comparison of malaria parasite prevalence as determined by each method was performed.ResultsParasite prevalence in the high transmission site of Obom was estimated at 71.4%, 61.9%, 60%, 37.8% and 19.1% by Nested PCR, the HRP2 bead assay, PET-PCR, HRP2-RDT and microscopy respectively. Parasite prevalence in the low transmission site of Asutsuare was estimated at 50.1%, 11.2%, 5.6%, 0% and 2.2% by Nested PCR, the HRP2 bead assay, PET-PCR, RDT and microscopy, respectively. The diagnostic performance of Nested PCR, PET-PCR and the HRP2 bead assay was similar in Obom but in Asutsuare, Nested PCR had a significantly higher sensitivity than PET-PCR and the HRP2 bead assay, which had similar sensitivity.ConclusionsNested PCR exhibited the highest sensitivity by identifying the highest prevalence of asymptomatic P. falciparum in both the high and low parasite prevalence settings. However, parasite prevalence estimated by the HRP2 bead assay and PET-PCR had the highest level of inter-rater agreement relative to all the other tools tested and have the advantage of requiring fewer processing steps relative to Nested PCR and producing quantitative results.

Project description:BackgroundGenetic diversity in Plasmodium falciparum (P. falciparum) parasites is a major hurdle to the control of malaria. This study monitored changes in the genetic diversity and the multiplicity of P. falciparum parasite infection in asymptomatic children living in southern Ghana at 3 month intervals between April 2015 and January 2016.MethodsFilter paper blood spots (DBS) were collected quarterly from children living in Obom, a community with perennial malaria transmission and Abura, a community with seasonal malaria transmission. Genomic DNA was extracted from the DBS and used in polymerase chain reaction (PCR)-based genotyping of the merozoite surface protein 1 (msp 1) and merozoite surface protein 2 (msp 2) genes.ResultsOut of a total of 787 samples that were collected from the two study sites, 59.2% (466/787) tested positive for P. falciparum. The msp 1 and msp 2 genes were successfully amplified from 73.8% (344/466) and 82.5% (385/466) of the P. falciparum positive samples respectively. The geometric mean MOI in Abura ranged between 1.17 (95% CI: 1.08-1.28) and 1.48 (95% CI: 1.36-1.60) and was significantly lower (p < 0.01, Dunn's multiple comparison test) than that determined in Obom, where the geometric mean MOI ranged between 1.82 (95% CI: 1.58-2.08) and 2.50 (95% CI: 2.33-2.678) over the study period. Whilst the msp 1 R033:MAD20:KI allelic family ratio was dynamic, the msp 2 3D7:FC27 allelic family ratio remained relatively stable across the changing seasons in both sites.ConclusionsThis study shows that seasonal variations in parasite diversity in these communities can be better estimated by msp 1 rather than msp 2 due to the constantly changing relative intra allelic frequencies observed in msp 1 and the fact that the dominance of any msp 2 allele was dependent on the transmission setting but not on the season as opposed to the dominance of any msp 1 allele, which was dependent on both the season and the transmission setting.

Project description:Background: We employed DNA microarray technology to investigate the host response to Streptococcus pneumoniae in a mouse model of asymptomatic carriage. Over a period of six weeks, we profiled transcript abundance and complexity in the Nasal Associated Lymphoid Tissue (NALT) to identify genes whose expression differed between pneumococcal-colonized and uncolonized states. Results: Colonization with S. pneumoniae altered the expression of hundreds of genes over the course of the study, demonstrating that carriage is a dynamic process characterized by increased expression of a set of early inflammatory responses, including induction of a Type 1 Interferon response, and the production of several antimicrobial factors. Subsequent to this initial inflammatory response, we observed increases in transcripts associated with T cell development and activation, as well as wounding, basement membrane remodeling, and cell proliferation. Our analysis suggests that microbial colonization induced expression of genes encoding components critical for controlling JAK/STAT signaling, including stat1, stat2, socs3, and mapk1, as well as induction of several Type 1 Interferon-inducible genes and other antimicrobial factors at the earliest stages of colonization. Conclusions: Examining multiple time points over six weeks of colonization demonstrated that asymptomatic carriage stimulates a dynamic host response characterized by temporal waves with distinct biological programs. Our data suggest that the usual response to the presence of the pneumocccus is an initial controlled inflammatory response followed by activation of host physiological processes such as response to wounding, basement membrane remodeling, and increasing cellular numbers that ultimately allow the host to maintain an intact epithelium and eventually mount a preventive adaptive immune response. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied.

Project description:BackgroundThe gametocyte stage of Plasmodium falciparum is considered an important target for disrupting malaria transmission. Indications are that various demographic groups, such as children and pregnant women may differ in risk of harbouring gametocytes, which may be crucial for targeted control. In this study, the relationship between the prevalence and multiplicity of P. falciparum, asexual parasite infections and gametocytaemia was assessed in three different demographic groups in an area of southern Ghana with low malaria endemicity. Levels of antibody responses to Pfs230 were also assessed as a proxy for the presence of gametocytes.MethodsThe study involved multiple cross-sectional sampling of children (N?=?184, aged 2-15 years), male and non-pregnant female adults (N?=?154, aged 16-65 years) and pregnant women (N?=?125, aged 18-45 years) from Asutsuare in the Shai Osudoku District of Greater Accra Region in Ghana. Asexual parasitaemia was detected by microscopy and PCR, and gametocytaemia was assessed by Pfs25-real time PCR. Multiclonal P. falciparum infections were estimated by msp2 genotyping and an indirect ELISA was used to measure plasma IgG antibodies to Pfs230 antigen.ResultsOverall, children and pregnant women had higher prevalence of submicroscopic gametocytes (39.5% and 29.7%, respectively) compared to adults (17.4%). Multiplicity of infection observed amongst children (3.1) and pregnant women (3.9) were found to be significantly higher (P?=?0.006) compared with adults (2.7). Risk of gametocyte carriage was higher in individuals infected with P. falciparum having both Pfmsp2 3D7 and FC27 parasite types (OR?=?5.92, 95% CI 1.56-22.54, P?=?0.009) compared with those infected with only 3D7 or FC27 parasite types. In agreement with the parasite prevalence data, anti-Pfs230 antibody levels were lower in gametocyte positive adults (??=?-?0.57, 95% CI -?0.81, -?0.34, P?<?0.001) compared to children.ConclusionsThese findings suggest that children and pregnant women are particularly important as P. falciparum submicroscopic gametocyte reservoirs and represent important focus groups for control interventions. The number of clones increased in individuals carrying gametocytes compared to those who did not carry gametocytes. The higher anti-gametocyte antibody levels in children suggests recent exposure and may be a marker of gametocyte carriage.

Dataset Information

Asymptomatic carriage of Plasmodium falciparum by individuals with variant blood groups and haemoglobin genotypes in southern Ghana.

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Asymptomatic carriage of Plasmodium falciparum by individuals with variant blood groups and haemoglobin genotypes in southern Ghana.

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