Samuel Acquah

Principal component analysis of socioeconomic factors and their association with malaria in children from the Ashanti Region, Ghana.

BackgroundThe socioeconomic and sociodemographic situation are important components for the design and assessment of malaria control measures. In malaria endemic areas, however, valid classification of socioeconomic factors is difficult due to the lack of standardized tax and income data. The objective of this study was to quantify household socioeconomic levels using principal component analyses (PCA) to a set of indicator variables and to use a classification scheme for the multivariate analysis of children < 15 years of age presented with and without malaria to an outpatient department of a rural hospital.MethodsIn total, 1,496 children presenting to the hospital were examined for malaria parasites and interviewed with a standardized questionnaire. The information of eleven indicators of the familys housing situation was reduced by PCA to a socioeconomic score, which was then classified into three socioeconomic status (poor, average and rich). Their influence on the malaria occurrence was analysed together with malaria risk co-factors, such as sex, parents educational and ethnic background, number of children living in a household, applied malaria protection measures, place of residence and age of the child and the mother.ResultsThe multivariate regression analysis demonstrated that the proportion of children with malaria decreased with increasing socioeconomic status as classified by PCA (p < 0.05). Other independent factors for malaria risk were the use of malaria protection measures (p < 0.05), the place of residence (p < 0.05), and the age of the child (p < 0.05).ConclusionsThe socioeconomic situation is significantly associated with malaria even in holoendemic rural areas where economic differences are not much pronounced. Valid classification of the socioeconomic level is crucial to be considered as confounder in intervention trials and in the planning of malaria control measures.

Modeling the Relationship between Precipitation and Malaria Incidence in Children from a Holoendemic Area in Ghana

Climatic factors influence the incidence of vector-borne diseases such as malaria. They modify the abundance of mosquito populations, the length of the extrinsic parasite cycle in the mosquito, the malarial dynamics, and the emergence of epidemics in areas of low endemicity. The objective of this study was to investigate temporal associations between weekly malaria incidence in 1,993 children < 15 years of age and weekly rainfall. A time series analysis was conducted by using cross-correlation function and autoregressive modeling. The regression model showed that the level of rainfall predicted the malaria incidence after a time lag of 9 weeks (mean = 60 days) and after a time lag between one and two weeks. The analyses provide evidence that high-resolution precipitation data can directly predict malaria incidence in a highly endemic area. Such models might enable the development of early warning systems and support intervention measures.

Comparative evaluation of two rapid field tests for malaria diagnosis: Partec Rapid Malaria Test ® and Binax Now ® Malaria Rapid Diagnostic Test

BackgroundAbout 90% of all malaria deaths in sub-Saharan Africa occur in children under five years. Fast and reliable diagnosis of malaria requires confirmation of the presence of malaria parasites in the blood of patients with fever or history suggestive of malaria; hence a prompt and accurate diagnosis of malaria is the key to effective disease management. Confirmation of malaria infection requires the availability of a rapid, sensitive, and specific testing at an affordable cost. We compared two recent methods (the novel Partec Rapid Malaria Test® (PT) and the Binax Now® Malaria Rapid Diagnostic Test (BN RDT) with the conventional Giemsa stain microscopy (GM) for the diagnosis of malaria among children in a clinical laboratory of a hospital in a rural endemic area of Ghana.MethodsBlood samples were collected from 263 children admitted with fever or a history of fever to the pediatric clinic of the Agogo Presbyterian Hospital. The three different test methods PT, BN RDT and GM were performed independently by well trained and competent laboratory staff to assess the presence of malaria parasites. Results were analyzed and compared using GM as the reference standard.ResultsIn 107 (40.7%) of 263 study participants, Plasmodium sp. was detected by GM. PT and BN RDT showed positive results in 111 (42.2%) and 114 (43.4%), respectively. Compared to GM reference standard, the sensitivities of the PT and BN RDT were 100% (95% CI: 96.6-100) and 97.2% (95% CI: 92.0-99.4), respectively, specificities were 97.4% (95% CI: 93.6-99.3) and 93.6% (95% CI: 88.5-96.9), respectively. There was a strong agreement (kappa) between the applied test methods (GM vs PT: 0.97; p < 0.001 and GM vs BN RDT: 0.90; p < 0.001). The average turnaround time per tests was 17 minutes.ConclusionIn this study two rapid malaria tests, PT and BN RDT, demonstrated a good quality of their performance compared to conventional GM. Both methods require little training, have short turnaround times, are applicable as well as affordable and can therefore be considered as alternative diagnostic tools in malaria endemic areas. The species of Plasmodium cannot be identified.

Spatial analysis of land cover determinants of malaria incidence in the Ashanti Region, Ghana.

Malaria belongs to the infectious diseases with the highest morbidity and mortality worldwide. As a vector-borne disease malaria distribution is strongly influenced by environmental factors. The aim of this study was to investigate the association between malaria risk and different land cover classes by using high-resolution multispectral Ikonos images and Poisson regression analyses. The association of malaria incidence with land cover around 12 villages in the Ashanti Region, Ghana, was assessed in 1,988 children <15 years of age. The median malaria incidence was 85.7 per 1,000 inhabitants and year (range 28.4–272.7). Swampy areas and banana/plantain production in the proximity of villages were strong predictors of a high malaria incidence. An increase of 10% of swampy area coverage in the 2 km radius around a village led to a 43% higher incidence (relative risk [RR] = 1.43, p<0.001). Each 10% increase of area with banana/plantain production around a village tripled the risk for malaria (RR = 3.25, p<0.001). An increase in forested area of 10% was associated with a 47% decrease of malaria incidence (RR = 0.53, p = 0.029). Distinct cultivation in the proximity of homesteads was associated with childhood malaria in a rural area in Ghana. The analyses demonstrate the usefulness of satellite images for the prediction of malaria endemicity. Thus, planning and monitoring of malaria control measures should be assisted by models based on geographic information systems.

Susceptibility of bacterial etiological agents to commonly-used antimicrobial agents in children with sepsis at the Tamale Teaching Hospital

BackgroundBloodstream infections in neonates and infants are life-threatening emergencies. Identification of the common bacteria causing such infections and their susceptibility patterns will provide necessary information for timely intervention. This study is aimed at determining the susceptibilities of bacterial etiological agents to commonly-used antimicrobial agents for empirical treatment of suspected bacterial septicaemia in children.MethodsThis is a hospital based retrospective analysis of blood cultures from infants to children up to 14 years of age with preliminary diagnosis of sepsis and admitted to the Neonatal Intensive Care Unit (NICU) and Paediatric Wards of the Teaching Hospital Tamale from July 2011 to January 2012.ResultsOut of 331 blood specimens cultured, the prevalence of confirmed bacterial sepsis was 25.9% (86/331). Point prevalence for confirmed cases from NICU was 44.4% (28/63) and 21.6% (58/268) from the Paediatric ward. Gram positive cocci (GPC) were the predominant isolates with Coagulase positive (32.2%) and Coagulase-negative (28.7%) Staphylococci accounting for 60.9% of the total isolates. Gram negative rods (GNR) comprised 39.1% of all isolates with Klebsiella, E.coli and Salmonella being the most common organisms isolated. Klebsiella was the most frequent GNR from the NICU and Salmonella typhi was predominantly isolated from the paediatric ward. Acinetobacter showed 100.0% susceptibility to Ceftriaxone and Cefotaxime but was resistant (100.0%) to Ampicillin, Tetracycline and Cotrimoxazole. Escherichia coli and Klebsiella were 80.0% and 91.0% susceptible to Ceftriaxone and Cefotaxime respectively. Klebsiella species showed 8.3% susceptibility to Tetracycline but was resistant to Ampicillin and Cotrimoxazole. Escherichia coli showed 40.0% susceptibility to Ampicillin, Chloramphenicol and Cotrimoxazole; 20.0% susceptibility to Tetracycline and 80.0% susceptible to Gentamicin and Cefuroxime. Coagulase negative Staphylococci was susceptible to Gentamicin (72.0%) but Coagulase positive Staphylococci showed intermediate sensitivity to Gentamicin (42.9%).ConclusionCoagulase Negative, Coagulase Positive Staphylococci, Salmonella and Klebsiella were the aetiological agents of bloodstream infection among children at TTH. While gram-positive and gram-negative bacteria showed low susceptibility to Ampicillin, Tetracycline and Cotrimoxazole, the GNR were susceptible to Gentamicin and third-generation cephalosporins.

Comparison of the Novel Partec Rapid Malaria Test to the Conventional Giemsa Stain and the Gold Standard Real-Time PCR

ABSTRACT Malaria remains the single most frequent cause of death in Africa, killing one child every 30 s, but treatment decisions are often made only on clinical diagnosis, as laboratory techniques to confirm the clinical suspicion are labor intensive and costly. In this study, we evaluated the recently developed Partec rapid malaria test (PM) for the detection of Plasmodium spp. in human blood from patients in an area where malaria is endemic and compared the results with those of thick blood film Giemsa stain (GS) in terms of its performance and operational characteristics, using real-time (RT) PCR as the gold standard. The sensitivities of the PM and the GS were 62.2% (95% CI, 56.3 to 67.8) and 61.8% (95% CI, 55.9 to 67.4), respectively, while the specificities were 96.0% (95% CI, 92.3 to 98.3) and 98% (95% CI, 95.0 to 99.5), respectively. There was an excellent agreement between the results for the PM and those of the GS (k [level of agreement] = 0.96; P < 0.001). The results for the PM were obtained more quickly and at less cost than those for the GS. The performance characteristics of the PM were almost equal to those of the GS, but the operational characteristics were better, and the PM can therefore be considered as an alternative method for GS.

Human Parvovirus 4 in Nasal and Fecal Specimens from Children, Ghana

Nonparenteral transmission might contribute to human parvovirus 4 (PARV4) infections in sub-Saharan Africa. PARV4 DNA was detected in 8 (0.83%) of 961 nasal samples and 5 (0.53%) of 943 fecal samples from 1,904 children in Ghana. Virus concentrations ≤6–7 log10 copies/mL suggest respiratory or fecal–oral modes of PARV4 transmission.

Increased detection of invasive enteropathogenic bacteria in pre-incubated blood culture materials by real-time PCR in comparison with automated incubation in Sub-Saharan Africa

Abstract Background: Invasive enteropathogenic bacteria can cause systemic infections. Data from studies with PCR detection suggest, at least for Salmonella enterica, that blood culture may lead to underestimation in the tropics. Corresponding data are lacking for other invasive enteropathogenic bacteria. We compared classical blood culture and molecular methods for the diagnosis of blood infections. Methods: A real-time multiplex PCR for Salmonella spp., Shigella spp./entero- invasive Escherichia coli (EIEC), Yersinia spp., and Campylobacter jejuni was applied to 2321 retained blood culture samples from Ghanaian patients, after enrichment by automated culture. Results: PCR detected Salmonella DNA in 56 out of 58 pre-incubated Ghanaian blood cultures with growth of S. enterica. In 2 samples molecular diagnosis was only possible after 1:10 dilution. Twenty-two samples negative by blood culture and 1 positive with Micrococcus spp. were PCR-positive for Salmonella spp. In addition, 3 Shigella spp./EIEC, 2 Yersinia spp., and 1 C. jejuni were detected by PCR but not by culture growth. Conclusions: Real-time PCR was more sensitive in identifying invasive enteropathogenic bacteria than automated blood culture, which is hampered by a lack of evidence-based standardization of pre-analytic conditions in the tropics. Primary agar culture and Gram-staining prior to automated blood culture is advisable in cases where transportation times are long.

Predictive value of fever and palmar pallor for P. falciparum parasitaemia in children from an endemic area.

Introduction Although the incidence of Plasmodium falciparum malaria in some parts of sub-Saharan Africa is reported to decline and other conditions, causing similar symptoms as clinical malaria are gaining in relevance, presumptive anti-malarial treatment is still common. This study traced for age-dependent signs and symptoms predictive for P. falciparum parasitaemia. Methods In total, 5447 visits of 3641 patients between 2–60 months of age who attended an outpatient department (OPD) of a rural hospital in the Ashanti Region, Ghana, were analysed. All Children were examined by a paediatrician and a full blood count and thick smear were done. A Classification and Regression Tree (CART) model was used to generate a clinical decision tree to predict malarial parasitaemia a7nd predictive values of all symptoms were calculated. Results Malarial parasitaemia was detected in children between 2–12 months and between 12–60 months of age with a prevalence of 13.8% and 30.6%, respectively. The CART-model revealed age-dependent differences in the ability of the variables to predict parasitaemia. While palmar pallor was the most important symptom in children between 2–12 months, a report of fever and an elevated body temperature of ≥37.5°C gained in relevance in children between 12–60 months. The variable palmar pallor was significantly (p<0.001) associated with lower haemoglobin levels in children of all ages. Compared to the Integrated Management of Childhood Illness (IMCI) algorithm the CART-model had much lower sensitivities, but higher specificities and positive predictive values for a malarial parasitaemia. Conclusions Use of age-derived algorithms increases the specificity of the prediction for P. falciparum parasitaemia. The predictive value of palmar pallor should be underlined in health worker training. Due to a lack of sensitivity neither the best algorithm nor palmar pallor as a single sign are eligible for decision-making and cannot replace presumptive treatment or laboratory diagnosis.

Fluorescence in situ hybridization (FISH) for rapid identification of Salmonella spp. from agar and blood culture broth—An option for the tropics?

BACKGROUND Salmonella enterica is an important cause of diarrhea with the potential to cause systemic infection including sepsis, particularly in the tropics. Sepsis in particular requires quick and reliable identification to allow a rapid optimization of antibiotic therapy. We describe the establishment and evaluation of fluorescence in situ hybridization (FISH) as a rapid and easy-to-perform molecular identification procedure from agar and blood culture broths. METHODS Two newly developed FISH probes with specificity for Salmonella spp. were evaluated with 10 reference strains, 448 clinical isolates of Gram-negative bacteria from Germany and Ghana including 316 Salmonella spp. strains, and 39 environmental Salmonella spp. isolates from rivers and streams in Ghana. One FISH probe was further tested with 207 pre-incubated blood culture broths from Germany with Gram-negative rod-shaped bacteria in Gram stain. RESULTS Evaluation of the newly designed FISH probes demonstrated sensitivity of 99.2% and specificity of 98.4% for clinical isolates, sensitivity of 97.4% for environmental Salmonella spp. isolates, and sensitivity of 100% and specificity of 99.5% for blood culture materials. CONCLUSIONS FISH proved to be highly reliable for a rapid identification of Salmonella spp. directly from pre-incubated blood culture broths as well as after growth on agar. The inexpensive and easy-to-perform procedure is particularly suitable for resource-limited areas where more sophisticated procedures are not available.