Spatial mapping and prediction of Plasmodium falciparum infection risk among school-aged children in Côte d'Ivoire

BACKGROUND: In Côte d'Ivoire, malaria remains a major public health issue, and thus a priority to be tackled. The aim of this study was to identify spatially explicit indicators of Plasmodium falciparum infection among school-aged children and to undertake a model-based spatial prediction of P. falciparum infection risk using environmental predictors. METHODS: A cross-sectional survey was conducted, including parasitological examinations and interviews with more than 5,000 children from 93 schools across Côte d'Ivoire. A finger-prick blood sample was obtained from each child to determine Plasmodium species-specific infection and parasitaemia using Giemsa-stained thick and thin blood films. Household socioeconomic status was assessed through asset ownership and household characteristics. Children were interviewed for preventive measures against malaria. Environmental data were gathered from satellite images and digitized maps. A Bayesian geostatistical stochastic search variable selection procedure was employed to identify factors related to P. falciparum infection risk. Bayesian geostatistical logistic regression models were used to map the spatial distribution of P. falciparum infection and to predict the infection prevalence at non-sampled locations via Bayesian kriging. RESULTS: Complete data sets were available from 5,322 children aged 5-16 years across Côte d'Ivoire. P. falciparum was the predominant species (94.5 %). The Bayesian geostatistical variable selection procedure identified land cover and socioeconomic status as important predictors for infection risk with P. falciparum. Model-based prediction identified high P. falciparum infection risk in the north, central-east, south-east, west and south-west of Côte d'Ivoire. Low-risk areas were found in the south-eastern area close to Abidjan and the south-central and west-central part of the country. CONCLUSIONS: The P. falciparum infection risk and related uncertainty estimates for school-aged children in Côte d'Ivoire represent the most up-to-date malaria risk maps. These tools can be used for spatial targeting of malaria control interventions

Health-related quality of life among school children with parasitic infections : findings from a national cross-sectional survey in Côte d'Ivoire

Parasitic infections are still of considerable public health relevance, notably among children in low- and middle-income countries. Measures to assess the magnitude of ill-health in infected individuals, however, are debated and patient-based proxies through generic health-related quality of life (HrQoL) instruments are among the proposed strategies. Disability estimates based on HrQoL are still scarce and conflicting, and hence, there is a need to strengthen the current evidence-base.; Between November 2011 and February 2012, a national school-based cross-sectional survey was conducted in Côte d'Ivoire. Children underwent parasitological and clinical examination to assess infection status with Plasmodium and helminth species and clinical parameters, and responded to a questionnaire interview incorporating sociodemographic characteristics, self-reported morbidity, and HrQoL. Validity analysis of the HrQoL instrument was performed, assessing floor and ceiling effects, internal consistency, and correlation with morbidity scores. Multivariate regression models were applied to identify significant associations between HrQoL and children's parasitic infection and clinical status.; Parasitological examination of 4,848 children aged 5-16 years revealed Plasmodium spp., hookworm, Schistosoma haematobium, Schistosoma mansoni, Ascaris lumbricoides, and Trichuris trichiura prevalences of 75.0%, 17.2%, 5.7%, 3.7%, 1.8%, and 1.3%, respectively. Anemic children showed a significant 1-point reduction in self-rated HrQoL on a scale from 0 to 100, whereas no significant negative association between HrQoL and parasite infection was observed. The 12-item HrQoL questionnaire proofed useful, as floor and ceiling effects were negligible, internally consistent (Cronbach's alpha = 0.71), and valid, as revealed by significant negative correlations and associations with children's self-reported and clinically assessed morbidity.; Our results suggest that HrQoL tools are not sufficiently sensitive to assess subtle morbidities due to parasitic infection in Ivorian school-aged children. However, more advanced morbid sequelae (e.g., anemia), were measurable by the instrument's health construct. Further investigations on health impacts of parasitic infection among school-aged children and refinement of generic HrQoL questionnaires are warranted

Bayesian risk mapping and model-based estimation of Schistosoma haematobium : Schistosoma mansoni co-distribution in Côte d'Ivoire

Schistosoma haematobium and Schistosoma mansoni are blood flukes that cause urogenital and intestinal schistosomiasis, respectively. In Côte d'Ivoire, both species are endemic and control efforts are being scaled up. Accurate knowledge of the geographical distribution, including delineation of high-risk areas, is a central feature for spatial targeting of interventions. Thus far, model-based predictive risk mapping of schistosomiasis has relied on historical data of separate parasite species.; We analyzed data pertaining to Schistosoma infection among school-aged children obtained from a national, cross-sectional survey conducted between November 2011 and February 2012. More than 5,000 children in 92 schools across Côte d'Ivoire participated. Bayesian geostatistical multinomial models were developed to assess infection risk, including S. haematobium-S. mansoni co-infection. The predicted risk of schistosomiasis was utilized to estimate the number of children that need preventive chemotherapy with praziquantel according to World Health Organization guidelines.; We estimated that 8.9% of school-aged children in Côte d'Ivoire are affected by schistosomiasis; 5.3% with S. haematobium and 3.8% with S. mansoni. Approximately 2 million annualized praziquantel treatments would be required for preventive chemotherapy at health districts level. The distinct spatial patterns of S. haematobium and S. mansoni imply that co-infection is of little importance across the country.; We provide a comprehensive analysis of the spatial distribution of schistosomiasis risk among school-aged children in Côte d'Ivoire and a strong empirical basis for a rational targeting of control interventions

Disparities of Plasmodium falciparum infection, malaria-related morbidity and access to malaria prevention and treatment among school-aged children : a national cross-sectional survey in Côte d'Ivoire

There is limited knowledge on the malaria burden of school-aged children in Côte d'Ivoire. The aim of this study was to assess Plasmodium falciparum infection, malaria-related morbidity, use of preventive measures and treatment against malaria, and physical access to health structures among school-aged children across Côte d'Ivoire.; A national, cross-sectional study was designed, consisting of clinical and parasitological examinations and interviews with schoolchildren. More than 5,000 children from 93 schools in Côte d'Ivoire were interviewed to determine household socioeconomic status, self-reported morbidity and means of malaria prevention and treatment. Finger-prick blood samples were collected and Plasmodium infection and parasitaemia determined using Giemsa-stained blood films and a rapid diagnostic test (RDT). Haemoglobin levels and body temperature were measured. Children were classified into wealth quintiles using household assets and principal components analysis (PCA). The concentration index was employed to determine significant trends of health variables according to wealth quintiles. Logistic and binomial negative regression analyses were done to investigate for associations between P. falciparum prevalence and parasitaemia and any health-related variable.; The prevalence of P. falciparum was 73.9% according to combined microscopy and RDT results with a geometric mean of parasitaemia among infected children of 499 parasites/μl of blood. Infection with P. falciparum was significantly associated with sex, socioeconomic status and study setting, while parasitaemia was associated with age. The rate of bed net use was low compared to the rate of bed net ownership. Preventive measures (bed net ownership, insecticide spray and the reported use of malaria treatment) were more frequently mentioned by children from wealthier households who were at lower risk of P. falciparum infection. Self-reported morbidity (headache) and clinical morbidity (anaemia) were more often reported by children from less wealthy households.; Seven out of ten school-aged children in Côte d'Ivoire are infected with P. falciparum and malaria-related morbidity is considerable. Furthermore, this study points out that bed net usage is quite low and there are important inequalities in preventive measures and treatment. These results can guide equity-oriented malaria control strategies in Côte d'Ivoire

Data sources and properties of the variables used to estimate the schistosomiasis risk in Côte d′Ivoire in late 2011/early 2012.

1<p>Moderate Resolution Imaging Spectroradiometer (MODIS). Available at: <a href="https://lpdaac.usgs.gov/(accessed" target="_blank">https://lpdaac.usgs.gov/(accessed</a>: 1 October 2012).</p>2<p>Africa Data Dissemination Service (ADDS). Available at: <a href="http://earlywarning.usgs.gov/adds/(accessed" target="_blank">http://earlywarning.usgs.gov/adds/(accessed</a>: 1 October 2012).</p>3<p>Digital Elevation Model (DEM). Available at: <a href="http://eros.usgs.gov/(accessed" target="_blank">http://eros.usgs.gov/(accessed</a>: 1 October 2012).</p>4<p>HealthMapper database. Available at: <a href="http://gis.emro.who.int/PublicHealthMappingGIS/HealthMapper.aspx" target="_blank">http://gis.emro.who.int/PublicHealthMappingGIS/HealthMapper.aspx</a></p><p>(accessed: 1 October 2012).</p>5<p>ISRIC-WISE database (WISE3). Available at: <a href="http://www.isric.org/" target="_blank">http://www.isric.org/</a>(accessed: 1 October 2012).</p>6<p>Last of the Wild Project version 2, 2005 (LWP-2): Global Human Influence Index (HII) dataset (geographic)</p><p>Wildlife Conservation Society International Earth (WCS) and Center for International Earth Science Information Network (CIESIN). Available at: <a href="http://sedac.ciesin.columbia.edu/data/set/wildareas-v2-human-influence-index-geographic" target="_blank">http://sedac.ciesin.columbia.edu/data/set/wildareas-v2-human-influence-index-geographic</a> (accessed: 1 October 2012).</p>7<p>Calculated with the Iterative Self-Organizing Data Analysis Technique (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003407#pntd.0003407-Schur2" target="_blank">[17]</a>).</p>8<p>Demographic and Health Surveys. Available at: <a href="http://www.measuredhs.com" target="_blank">http://www.measuredhs.com</a> (accessed: 1 October 2012).</p>9<p>Multiple Indicator Cluster Surveys. Available at: <a href="http://www.childinfo.org/mics.html" target="_blank">http://www.childinfo.org/mics.html</a> (accessed: 1 October 2012).</p>10<p>World Health Surveys. Available at: <a href="http://www.who.int/healthinfo/survey/en/index.html" target="_blank">http://www.who.int/healthinfo/survey/en/index.html</a> (accessed: 1 October 2012).</p>11<p>Gridded Population of the World version 3. Available at: <a href="http://sedac.ciesin.org/gpw/(accessed" target="_blank">http://sedac.ciesin.org/gpw/(accessed</a>: 1 October 2012).</p>12<p>AfriPop version 2.0. Available upon request at: <a href="http://www.afripop.org" target="_blank">http://www.afripop.org</a> (accessed: 1 October 2012).</p><p>Data sources and properties of the variables used to estimate the schistosomiasis risk in Côte d′Ivoire in late 2011/early 2012.</p

Misclassification of the surveyed schools by the predicted risk at school and health districts level.

<p>Number and percentage of schools overestimated and underestimated are given according to endemic thresholds defined by WHO for control interventions.</p><p>Misclassification of the surveyed schools by the predicted risk at school and health districts level.</p

Mean overall and domain HrQoL scores grouped by sociodemographic, parasitological, and clinical variables from 4,848 school children (2,269 females, 2,579 males) in Côte d'Ivoire.

<p>Domain 1 = physical wellbeing; domain 2 = psychosocial wellbeing; domain 3 = environmental wellbeing.</p><p>*Statistically significant (p<0.05) based on Wilcoxon rank sum (for variables with 2 categories) and Kruskal-Wallis test (for variables with more than 2 categories).</p><p>Mean overall and domain HrQoL scores grouped by sociodemographic, parasitological, and clinical variables from 4,848 school children (2,269 females, 2,579 males) in Côte d'Ivoire.</p

Classification of Colon Polyps and Risk of Neoplastic Progression

Colorectal polyps are small clumps of cells and they are classified on the basis of their histological characteristics. Until recently, they have been divided into two major groups: neoplastic and non-neoplastic mucosal polyps. Adenomatous polyps contain epithelial neoplasia and their size and histology correlate with the risk of progression to carcinoma. Non-neoplastic polyps, instead, can be divided into several distinct and unrelated categories including hyperplastic, mucosal, juvenile, Peutz-Jeghers, and inflammatory. Adenomas are recognized as the precursor lesions for colorectal carcinoma and recently also some hyperplastic lesions, with serrated morphology, have been reported to display a significant risk of neoplastic progression through the so-called serrated pathway. The sequence adenoma-carcinoma is caused by different molecular pathways. The most frequent are those of chromosomal instability pathway; the microsatellite instability pathway; the serrated pathway. Molecular complexity can explain the morphological heterogeneity and the timing of neoplastic progression

Observed schistosomiasis prevalence in Côte d′Ivoire in late 2011/early 2012.

<p>A: Overall schistosomiasis, irrespective of the species; B: overall <i>S. mansoni</i>; C: overall <i>S. haematobium</i>; and D: co-infection with both species.</p

Utility and validity measures of HrQoL instrument from 4,848 school children with complete questionnaire data.

<p>This study was conducted between November 2011 and February 2012 in 92 schools all over Côte d'Ivoire.</p>a<p>Floor and ceiling correspond to the percentage of scores at the minimum (0) and maximum (100) of the scaling range. Floor or ceiling effects ≤15% are considered acceptable and providing reliable estimates <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003287#pntd.0003287-Terwee1" target="_blank">[44]</a>.</p>b<p>All items of the HrQoL instrument added up to the Cronbach α values indicating measurement of the same concept. Values of α≥0.7 are recommended for comparison between groups <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003287#pntd.0003287-Nunnally1" target="_blank">[56]</a>.</p><p>To assess the relationship between HrQoL and VAS scores with symptom and disease reporting, a variable providing the total number of self-reported symptoms (n = 11) and diseases (n = 8) for each child was generated first, with a possible range of 0 to 19. Subsequently, Spearman rank correlation and linear regression analysis was performed with instrument scores in relation to the number of self-reported morbidities. All correlations and associations where of negative direction indicating decreasing HrQoL scores for increasing numbers of self-reported symptoms and diseases.</p><p>Similarly, a summary variable for 7 examined clinical signs (i.e., anemia, fever, hepatomegaly, splenomegaly, stunting, underweight, and wasting) was generated, with a possible range of 0 to 7, and relationship with HrQoL and VAS scores assessed using linear regression analysis. Particularly the physical health domain showed strong negative association with increased number of clinical signs.</p><p>*Statistically significant (p<0.05).</p><p>Utility and validity measures of HrQoL instrument from 4,848 school children with complete questionnaire data.</p