Browsing by Author "Larbi, I.A."
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Item Allergic characteristics of urban schoolchildren with atopic eczema in Ghana(Journal of the European Academy of Dermatology and Venereology, 2010-04) Hogewoning, A.A.; Larbi, I.A.; Addo, H.A.; Amoah, A.S.; Boakye, D.; Hartgers, F.; Yazdanbakhsh, M.; Van Ree, R.; Bouwes Bavinck, J.N.; Lavrijsen, A.P.M.Background: Atopic eczema is an increasing clinical problem in Africa. Objective: To determine allergic characteristics and to identify possible risk factors for eczema among schoolchildren in an urbanized area in Ghana. Patients and methods: Schoolchildren aged 3-16 years with eczema were recruited. For each patient, one to three age- and sex-matched controls were selected. All children completed a questionnaire and were skin prick tested with a panel of allergens. Blood was drawn to determine the total and allergen-specific IgE. Conditional logistic regression models with the matching factors included in the model were used to calculate the odds ratios and to adjust for possible confounders. Results: A total of 52 children with eczema (27 boys and 25 girls) and 99 controls were included. Levels of total IgE were found to be 9.1 (1.1; 78.4) times more often elevated in children with eczema. This association was mainly driven by elevated IgE levels against cockroach antigen. Children with eczema were found to have 2.0 (0.87; 4.7) times more often positive skin prick tests (SPT), but this association diminished to 1.2 (0.40; 3.6) after adjustment for total IgE levels. Frequent washing with soap was identified as a risk factor for the development of eczema among these children. Conclusion: Schoolchildren with eczema in Ghana were characterized by elevated IgE levels especially against cockroach antigen. The association between eczema and positive SPT was much weaker suggesting immune hyporesponsiveness of the skin. After adjustment for IgE level, SPT were less suitable to distinguish children with and without eczema. © 2010 European Academy of Dermatology and Venereology.Item Anemia Prvalence And Associated Factors Among School Age Children In Accra And Kumasi Metropolis In Ghana(ajfand, 2022) Egbi, G.; Larbi, I.A.; Nti, H.; Marquis, G.S.; Lartey, A.; Aryeetey, R.Anemia remains a serious public health concern, globally, affecting learning ability and physical development of children. Anemic children are at a higher risk of diminished economic productivity and low earning capacity in adulthood due to impaired school performance and reduced work capacity. Anemia contributes to about a quarter of Africa’s nutrition-related Disability Adjusted Life Years. The objective of this study was to determine the prevalence of anemia and its associated risk factors among school-aged children (SAC) between ages 9 and 15 years in urban Ghana. The analysis included a randomly selected subsample of 1,634 children from a larger study on nutrition of SAC enrolled between 2009 and 2012 in private and public basic schools in the Accra and Kumasi Metropolis in Ghana. Socio-demographic and household characteristics were collected with questionnaires. Weight and height were taken to the nearest 0.1kg and 0.1cm, respectively. Dietary information was collected using a food frequency questionnaire. Data were analyzed using IBM SPSS Statistic version 23. The relationship between hemoglobin levels and socio-demographic variables, and predictors of hemoglobin levels were determined using Chi-square and binary logistic regression. The mean hemoglobin concentration of the study participants was 12.9±1.3 g/dL. In Kumasi, SAC had higher mean hemoglobin concentration (13.1±1.2 g/dL) compared to those from Accra (12.6±1.3 g/dL; p=0.001). Mean hemoglobin concentration was significantly higher among males than females (13.0±1.4 g/dL vs 12.8±1.2 g/dL; p=0.002). Prevalence of anemia was 20.4%; mild anemia was most common (13.6% of total sample). Anemia cases were higher in public schools (24.6%) compared to private (18.2%). Two-thirds of anemia cases (64.0%) were from schools in Accra. Males had significantly higher prevalence of anemia (26.5%) than females (15.9%; p <0.05). In the adjusted logistic regression model, only city of residence (OR+1.65, 95% CI: 1.44–1.83), thinness (OR=2.60, 95% CI: 1.11-5.75), stunting (OR=1.85, 95% CI: 1.99-3.10) and overweight (OR=0.60, 95% CI: 0.36-0.94) were significantly associated with anemia. In this study, anemia was significantly associated with location and nutritional status.Item Application of a circulating-cathodic-antigen (CCA) strip test and real-time PCR, in comparison with microscopy, for the detection of Schistosoma haematobium in urine samples from Ghana(Annals Tropical of Medicine and Parasitology 102(7): 625-33, 2008) Obeng, B.B.; Aryeetey, Y.A.; de Dood, C.J.; Amoah, A.S.; Larbi, I.A.; Deelder, A.M.; Yazdanbakhsh, M.; Hartgers, F.C.; Boakye, D.A.; Verweij, J.J.; van Dam, G.J.; van Lieshout, L.In the detection of parasitic infection, the traditional methods based on microscopy often have low sensitivity and/or specificity compared with the newer, molecular tests. An assay based on real-time PCR and a reagent strip test for detecting circulating cathodic antigen (CCA) have both now been compared with urine filtration and microscopy, in the detection of Schistosoma haematobium infections. Urine samples, obtained from 74 'cases' in areas of Ghana with endemic S. haematobium and 79 'controls' from non-endemic areas, were each checked using the three methods. With the results of the filtration and microscopy taken as the 'gold standard', real-time PCR was found to be 100% specific and 89% sensitive whereas the CCA strips were 91% specific and 41% sensitive. With the samples found to contain > or =50 eggs/10 ml (indicating relatively intense infections), the sensitivities of the PCR and CCA were higher, at 100% and 62%, respectively. As expected, egg counts were negatively correlated with the number of amplification cycles needed, in the PCR, to give a signal that exceeded the background (r=-0.38; P<0.01). Although the real-time PCR and CCA strip tests are very different, both show promise in the detection of S. haematobium infections. The PCR has optimal specificity and high sensitivity but the specificity of the CCA strips and the sensitivity of both tools could still be improved. A more thorough re-evaluation of the sensitivity and specificity of microscopy and these newer diagnostic methods, with an estimation of the cost-effectiveness of each technique, is recommended.Item Enhanced toll-like receptor responsiveness associated with mitogen-activated protein kinase activation in Plasmodium falciparum-infected children(Infection and Immunity, 2008-09) Hartgers, F.C.; Obeng, B.B.; Voskamp, A.; Larbi, I.A.; Amoah, A.S.et.al.Acute Plasmodium falciparum infection is associated with strongly upregulated cytokine responses that are at least partly the result of activation of Toll-like receptors (TLRs). Whether and how TLR expression/responsiveness changes upon malarial infection is, however, currently not well understood. To assess this, we examined expression of TLRs and used the TLR ligand lipopolysaccharide (LPS) and Pam3Cys to stimulate peripheral blood mononuclear cells (PBMCs) from Ghanaian schoolchildren who live in a rural area where P. falciparum is endemic. Expression of TLR2 was higher, and responses to its ligand, Pam3Cys, were enhanced in P. falciparum-infected children compared to their uninfected counterparts. In cells from the same children, stimulation by Pam3Cys resulted in higher p38 mitogen-activated protein kinase activation and higher cytokine production. In vitro experiments confirmed that preincubation of PBMCs with P. falciparum-infected red blood cells enhanced responsiveness to TLR ligands. Taken together, the data indicate that P. falciparum-infected children in areas where malaria is endemic have an altered innate immune system, which might be important for the balance between immunity and pathology when new infections are encountered or when novel vaccines are introduced. Copyright © 2008, American Society for Microbiology. All Rights Reserved.Item Food allergy in Ghanaian schoolchildren: Data on sensitization and reported food allergy(International Archives of Allergy and Immunology, 2010-11) Obeng, B.B.; Amoah, A.S.; Larbi, I.A.; Yazdanbakhsh, M.; Van Ree, R.; Boakye, D.A.; Hartgers, F.C.Background: Epidemiological data on food allergy are scarce in African countries. We studied the prevalence of food sensitization in Ghanaian schoolchildren. Methods: Children (5-16 years; n = 1,714) from 9 Ghanaian schools were given parental consent to participate in the study. Adverse reactions and food consumption were determined by a questionnaire and atopy by skin prick testing (SPT) to peanut and 6 fruits. Subjects with positive SPTs were considered cases (n = 43) and matched with at least 1 control (n = 84), using age, sex, and school as matching criteria. Serum samples from case-control sets were analyzed for specific IgE (sIgE) to foods that elicited a positive SPT response in cases. Results: Overall, 11% of 1,407 children reported adverse reactions to foods, and 5% of 1,431 children showed a positive SPT reaction mostly directed against peanut and pineapple (both 2%). Although there was a positive association between adverse reactions and SPT responses to any food allergen in the urban children (adjusted OR = 3.6, 95% CI 1.2-10.8), most of the reported adverse reactions were not in children showing an SPT reaction to the specific food item. sIgE sensitization was very variable for the different foods, ranging from 0 to 100% in cases, and from 0 to 25% among controls. High IgE levels for a food item significantly increased the risk of SPT positivity to any food item in the urban, but not in the rural, schoolchildren. Conclusions: Specific foods were identified to be allergenic in Ghana. We show a good association between SPT and sIgE in urban, but not in rural, schoolchildren. However, there was no clear association between reported adverse reactions to food and SPT or sIgE. Copyright © 2010 S. Karger AG, Basel.Item Identification of dominant anti-glycan IgE responses in school-children by glycan microarray(Journal of Allergy and Clinical Immunology, 2018-03) Amoah, A.S.; Asuming-Brempong, E.K.; Obeng, B.B.; Versteeg, S.A.; Larbi, I.A.; Aryeetey, Y.; Platts-Mills, T.A.E.; Mari, A.; Brzezicka, K.; Gyan, B.A.; Mutocheluh, M.Item Lower Expression of TLR2 and SOCS-3 Is associated with schistosoma haematobium Infection and with lower risk for allergic reactivity in children living in a rural area in Ghana(PLoS Neglected Tropical Diseases 2(4): e227, 2008) Hartgers, F.C.; Obeng, B.B.; Kruize, Y.C.; Duijvestein, M.; de Breij, A.; Amoah, A.; Larbi, I.A.; van Ree, R.; Wilson, M.D.; Rodrigues, L.C.; Boakye, D.A.; Yazdanbakhsh, M.Background: Helminth infections are prevalent in rural areas of developing countries and have in some studies been negatively associated with allergic disorders and atopy. In this context little is known of the molecular mechanisms of modulation involved. We have characterized the innate immune responses, at the molecular level, in children according to their helminth infection status and their atopic reactivity to allergens. Methodology/Principal Findings: The mRNA expression of several genes of the innate immune system that have been associated with microbial exposure and allergy was examined in 120 school children in a rural area in Ghana. Helminth infections were common and atopy rare in the study area. The analysis of gene expression in ex vivo whole blood samples reflected the levels of corresponding proteins. Using this approach in a population of school children in whom the presence of Schistosoma haematobium infection was associated with protection from atopic reactivity, we found that the level of TLR2 and SOCS-3, genes associated with atopy in the children, were significantly downregulated by presence of S. haematobium infection. Conclusions: S. haematobium infections modulate the expression of genes of the innate immune system (TLR2 and SOCS-3); these are genes that are associated with increased allergic inflammatory processes, providing a molecular link between the negative association of this infection and atopy in rural children in Ghana.Item Molecular diagnosis of Schistosoma infections in urine samples of school children in Ghana(American Journal of Tropical Medicine and Hygiene, 2013-06) Aryeetey, Y.A.; Essien-Baidoo, S.; Larbi, I.A.; Ahmed, K.; Amoah, A.S.; Obeng, B.B.; Van Lieshout, L.; Yazdanbakhsh, M.; Boakye, D.A.; Verweij, J.J.Recent studies using an internal transcribed spacer (ITS)-based real-time polymerase chain reaction (PCR) for the detection of Schistosoma DNA in urine samples has shown high sensitivity and specificity when performed on controls and known microscopy-positive samples. In this study, using 730 urine samples collected from children in five primary schools from different communities in the Greater Accra region of Ghana, specific detection of Schistosoma DNA showed excellent sensitivity of 100% and 85.2% in urines with > 50 eggs/10 mL urine and ≤ 50 eggs/10 mL of urine, respectively. Additionally, Schistosoma-specific DNA was amplified in 102 of 673 samples in which Schistosoma eggs could not be detected with microscopy. Taking microscopy and/or PCR-positive samples as true positives, the negative predictive value calculated was 94.6-100% for each school sampled as compared with 54.3-95.7% using microscopy. This ITS-based real-time PCR proves to be a powerful tool in epidemiological surveys of schistosomiasis providing more precise and sensitive results than microscopy. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.Item Peanut-specific IgE antibodies in asymptomatic Ghanaian children possibly caused by carbohydrate determinant cross-reactivity(American Academy of Allergy, Asthma & Immunology, 2013-06-12) Amoah, A.S.; Obeng, B.B.; Larbi, I.A.; Versteeg, S.A.; Aryeetey, Y.; Akkerdaas, J.H.; Zuidmeer, L.; Lidholm, J.; Fernandez-Rivas, M.; Hartgers, F.C.; Boakye, D.A.; van Ree, R.; Yazdanbakhsh, M.The prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections. Objective: We sought to investigate peanut allergy in Ghana. Methods: In a cross-sectional survey among Ghanaian schoolchildren (n 5 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n 5 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively. Results: Adverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (>0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (>0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r 5 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity. Conclusions: Parasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found. (J Allergy Clin Immunol 2013;132:639-47.)Item Schistosome infection is negatively associated with mite atopy, but not wheeze and asthma in Ghanaian Schoolchildren(Clinical and Experimental Allergy, 2014-07) Obeng, B.B.; Amoah, A.S.; Larbi, I.A.; de Souza, D.K.; Uh, H.-W.; Fernández-Rivas, M.; van Ree, R.; Rodrigues, L.C.; Boakye, D.A.; Yazdanbakhsh, M.; Hartgers, F.C.Background: Epidemiological evidence suggests that helminth infection and rural living are inversely associated with allergic disorders. Objective: The aim of the study was to investigate the effect of helminth infections and urban versus rural residence on allergy in schoolchildren from Ghana. Methods: In a cross-sectional study of 1385 children from urban-high socio-economic status (SES), urban-low SES and rural schools, associations between body mass index (BMI), allergen-specific IgE (sIgE), parasitic infections and allergy outcomes were analysed. Allergy outcomes were skin prick test (SPT) reactivity, reported current wheeze and asthma. Results: Helminth infections were found predominantly among rural subjects, and the most common were hookworm (9.9%) and Schistosoma spp (9.5%). Being overweight was highest among urban-high SES (14.6%) compared to urban-low SES (5.5%) and rural children (8.6%). The prevalence of SPT reactivity to any allergen was 18.3%, and this was highest among rural children (21.4%) followed by urban-high SES (20.2%) and urban-low SES (10.5%) children. Overall, SPT reactivity to mite (12%) was most common. Wheeze and asthma were reported by 7.9% and 8.3%, respectively. In multivariate analyses, factors associated with mite SPT were BMI (aOR 2.43, 95% CI 1.28-4.60, P = 0.007), schistosome infection (aOR 0.15, 95% CI 0.05-0.41) and mite sIgE (aOR 7.40, 95% CI 5.62-9.73, P < 0.001) but not area. However, the association between mite IgE and SPT differed by area and was strongest among urban-high SES children (aOR = 15.58, 95% CI 7.05-34.43, P < 0.001). Compared to rural, urban-low SES area was negatively associated with current wheeze (aOR 0.41, 95% CI 0.20-0.83, P = 0.013). Both mite sIgE and mite SPT were significantly associated with current wheeze and asthma. Conclusion and Clinical Relevance: Infection with schistosomes appeared to protect against mite SPT reactivity. This needs to be confirmed in future studies, preferably in a longitudinal design where schistosome infections are treated and allergic reactions reassessed. © 2014 John Wiley & Sons Ltd.Item Urban-rural differences in the gene expression profiles of Ghanaian children(Genes and Immunity, 2014-05) Amoah, A.S.; Obeng, B.B.; May, L.; Kruize, Y.C.; Larbi, I.A.; Kabesch, M.; Wilson, M.D.; Hartgers, F.C.; Boakye, D.A.; Yazdanbakhsh, M.Recent studies indicate that urbanization is having a pronounced effect on disease patterns in developing countries. To understand the immunological basis of this, we examined mRNA expression in whole blood of genes involved in immune activation and regulation in 151 children aged 5-13 years attending rural, urban low socioeconomic status (SES) and urban high-SES schools in Ghana. Samples were also collected to detect helminth and malaria infections. Marked differences in gene expression were observed between the rural and urban areas as well as within the urban area. The expression of both interleukin (IL)-10 and programmed cell death protein 1 increased significantly across the schools from urban high SES to urban low SES to rural (P-trend <0.001). Although IL-10 gene expression was significantly elevated in the rural compared with the urban schools (P<0.001), this was not associated with parasitic infection. Significant differences in the expression of toll-like receptors (TLRs) and their signaling genes were seen between the two urban schools. Genetic differences could not fully account for the gene expression profiles in the different groups as shown by analysis of IL-10, TLR-2 and TLR-4 gene polymorphisms. Immune gene expression patterns are strongly influenced by environmental determinants and may underlie the effects of urbanization seen on health outcomes. © 2014 Macmillan Publishers Limited All rights reserved.