Effect of a serogroup A meningococcal conjugate vaccine (PsA-TT) on serogroup A meningococcal meningitis and carriage in Chad: a community study [corrected].

BACKGROUND: A serogroup A meningococcal polysaccharide-tetanus toxoid conjugate vaccine (PsA-TT, MenAfriVac) was licensed in India in 2009, and pre-qualified by WHO in 2010, on the basis of its safety and immunogenicity. This vaccine is now being deployed across the African meningitis belt. We studied the effect of PsA-TT on meningococcal meningitis and carriage in Chad during a serogroup A meningococcal meningitis epidemic. METHODS: We obtained data for the incidence of meningitis before and after vaccination from national records between January, 2009, and June, 2012. In 2012, surveillance was enhanced in regions where vaccination with PsA-TT had been undertaken in 2011, and in one district where a reactive vaccination campaign in response to an outbreak of meningitis was undertaken. Meningococcal carriage was studied in an age-stratified sample of residents aged 1-29 years of a rural area roughly 13-15 and 2-4 months before and 4-6 months after vaccination. Meningococci obtained from cerebrospinal fluid or oropharyngeal swabs were characterised by conventional microbiological and molecular methods. FINDINGS: Roughly 1·8 million individuals aged 1-29 years received one dose of PsA-TT during a vaccination campaign in three regions of Chad in and around the capital N'Djamena during 10 days in December, 2011. The incidence of meningitis during the 2012 meningitis season in these three regions was 2·48 per 100,000 (57 cases in the 2·3 million population), whereas in regions without mass vaccination, incidence was 43·8 per 100,000 (3809 cases per 8·7 million population), a 94% difference in crude incidence (p<0·0001), and an incidence rate ratio of 0·096 (95% CI 0·046-0·198). Despite enhanced surveillance, no case of serogroup A meningococcal meningitis was reported in the three vaccinated regions. 32 serogroup A carriers were identified in 4278 age-stratified individuals (0·75%) living in a rural area near the capital 2-4 months before vaccination, whereas only one serogroup A meningococcus was isolated in 5001 people living in the same community 4-6 months after vaccination (adjusted odds ratio 0·019, 95% CI 0·002-0·138; p<0·0001). INTERPRETATION: PSA-TT was highly effective at prevention of serogroup A invasive meningococcal disease and carriage in Chad. How long this protection will persist needs to be established. FUNDING: The Bill & Melinda Gates Foundation, the Wellcome Trust, and Médecins Sans Frontères.

Prediction of COVID-19 Using Genetic Deep Learning Convolutional Neural Network (GDCNN).

Rapid spread of Coronavirus disease COVID-19 leads to severe pneumonia and it is estimated to create a high impact on the healthcare system. An urgent need for early diagnosis is required for precise treatment, which in turn reduces the pressure in the health care system. Some of the standard image diagnosis available is Computed Tomography (CT) scan and Chest X-Ray (CXR). Even though a CT scan is considered a gold standard in diagnosis, CXR is most widely used due to widespread, faster, and cheaper. This study aims to provide a solution for identifying pneumonia due to COVID-19 and healthy lungs (normal person) using CXR images. One of the remarkable methods used for extracting a high dimensional feature from medical images is the Deep learning method. In this research, the state-of-the-art techniques used is Genetic Deep Learning Convolutional Neural Network (GDCNN). It is trained from the scratch for extracting features for classifying them between COVID-19 and normal images. A dataset consisting of more than 5000 CXR image samples is used for classifying pneumonia, normal and other pneumonia diseases. Training a GDCNN from scratch proves that, the proposed method performs better compared to other transfer learning techniques. Classification accuracy of 98.84%, the precision of 93%, the sensitivity of 100%, and specificity of 97.0% in COVID-19 prediction is achieved. Top classification accuracy obtained in this research reveals the best nominal rate in the identification of COVID-19 disease prediction in an unbalanced environment. The novel model proposed for classification proves to be better than the existing models such as ReseNet18, ReseNet50, Squeezenet, DenseNet-121, and Visual Geometry Group (VGG16).

Intermittent preventive treatment of malaria in infants: how does it work and where will it work?

We discuss the potential public health impact of IPTi by estimating the cases of malaria, anaemia and hospital admissions likely to be averted in different transmission settings; and we review the mechanism of action, choice of drugs regimens, and the effect on immunity of IPTi. IPTi using an efficacious drug is likely to substantially reduce cases of clinical malaria in moderate to high transmission settings. However, geographical heterogeneity in malaria transmission could hamper rolling out IPTi as a national policy.

Comparison of active and passive case detection systems in Jepara District, Indonesia.

This study compares the role and performance of active case detection (ACD) and passive case detection (PCD) in Jepara district, Indonesia. The number of blood slides examined and positive for malaria reported from 1994-1998 was retrieved from the district surveillance registers. Age of cases, parasite species, types of drugs and dosage, and time lapse were recorded from malaria registers at the three most endemic health centres. The quality of diagnosis was examined by re-reading 153 slides at the Department of Parasitology, Faculty of Medicine, Gadjah Mada University. Almost 60% of the 10,493 confirmed cases in Jepara district were identified from ACD. ACD detected significantly higher P. falciparum gametocyte infections than PCD (14.7% vs. 5.7%; p=0.002). The duration for slides prepared for examination was longer in ACD than in PCD (2.3 vs. 1.1 days; p<0.001), but this was still within the presumptive treatment period. Based on this we conclude that in the transition period to a decentralised health system, ACD for malaria parasites should be continued in a specified endemic area and therefore, efforts to retain the village malaria workers should be considered.

Experimental data on the properties of natural fiber particle reinforced polymer composite material.

This paper presents an experimental study on the development of polymer bio-composites. The powdered coconut shell, walnut shells and Rice husk are used as reinforcements with bio epoxy resin to form hybrid composite specimens. The fiber compositions in each specimen are 1:1 while the resin and hardener composition 10:1 respectively. The fabricated composites were tested as per ASTM standards to evaluate mechanical properties such as tensile strength, flexural strength, shear strength and impact strength are evaluated in both with moisture and without moisture. The result of test shows that hybrid composite has far better properties than single fibre glass reinforced composite under mechanical loads. However it is found that the incorporation of walnut shell and coconut shell fibre can improve the properties.

Entomological evaluation of malaria vectors at different altitudes in Hai district, northeastern Tanzania.

Entomological monitoring in four villages situated along an altitude transect in the Hai District of Northeastern Tanzania identified Anopheles arabiensis Patton as the principal vector of malaria and detected seasonal changes in vector behavior. Over a 13-mo sampling period, 10,557 mosquitoes were collected with CDC light traps, pyrethrum spray catches, and pit traps of which 5,969 (56.5%) wereAn. arabiensis, 762 (7.2%) wereAnopheles funestus Giles s.l., 3,578 (33.9%) were culicines, and 248 (2.3%) were nonvector anophelines. Vector densities declined rapidly with increasing altitude, demonstrating a 50% decrease in annual human biting rate for every 86-m rise in altitude. Light traps were found to be more efficient than spray catches for the collection of An. arabiensis. This observation was attributed to increased exophily of this species, most notably in the wet season, and is supported by seasonal changes in the human blood index and fed/gravid ratio. These results indicate that spray catches may underestimate the abundance of exophilic vectors such as An. arabiensis and that entomological monitoring may require more than one collection method, especially at low vector densities. The annual entomological inoculation rate (EIR) decreased sharply with increasing altitude, with large variation around the estimate at low vector densities. Increased transmission because of unpredictable short rains at low altitudes and spatial clustering of infective mosquitoes may contribute to elevated EIR estimates.

Effect of misclassification of causes of death in verbal autopsy: can it be adjusted?

BACKGROUND: Verbal autopsy (VA) is an indirect method of ascertaining cause of death from information about symptoms and signs obtained from bereaved relatives. This method has been used in several settings to assess cause-specific mortality. However, cause-specific mortality estimates obtained by VA are susceptible to bias due to misclassification of causes of death. One way of overcoming this limitation of VA is to adjust the crude VA estimate of cause-specific mortality fractions (CSMF) using the sensitivity and specificity of the VA tool. This paper explores the application of sensitivity and specificity of VA data obtained from a hospital-based validation study for adjusting the effect of misclassification error in VA data obtained from a demographic surveillance system. METHOD: Data from a multi-centre validation study of 796 adult VA, conducted in Tanzania, Ethiopia and Ghana, were used to explore the effect of distribution of causes of death in the validation study population and the pattern of misclassification on the sensitivity and specificity of VA. VA estimates of CSMF for six causes (acute febrile illness, diarrhoeal diseases, TB/AIDS, cardiovascular disorders, direct maternal causes and injures) were obtained from a demographic surveillance system in Morogoro Rural District in Tanzania. These were adjusted for misclassification error by using sensitivity and specificity values of VA obtained from the validation study in a model proposed for correcting the effect of misclassification error in morbidity prevalence surveys. RESULTS: Sensitivity and specificity of VA differed between the three validation study sites depending on the distribution of causes of death. These differences were explained by variations in the level and pattern of misclassification between sites. When these estimates of sensitivity and specificity were applied to data from the demographic surveillance system with a comparable structure of causes of death the difference between crude and adjusted VA estimates of CSMF ranged from 3 to 83%. CONCLUSION: Estimates of sensitivity and specificity obtained from hospital-based validation studies must be used cautiously as a de facto 'gold standard' for adjusting the misclassification error in CSMF derived from VA. It is not possible to use sensitivity and specificity estimates derived from a location-specific validation study to adjust for misclassification in VA data from populations with substantially different patterns of cause-specific mortality.

A case study of using artificial neural networks for classifying cause of death from verbal autopsy.

BACKGROUND: Artificial neural networks (ANN) are gaining prominence as a method of classification in a wide range of disciplines. In this study ANN is applied to data from a verbal autopsy study as a means of classifying cause of death. METHODS: A simulated ANN was trained on a subset of verbal autopsy data, and the performance was tested on the remaining data. The performance of the ANN models were compared to two other classification methods (physician review and logistic regression) which have been tested on the same verbal autopsy data. RESULTS: Artificial neural network models were as accurate as or better than the other techniques in estimating the cause-specific mortality fraction (CSMF). They estimated the CSMF within 10% of true value in 8 out of 16 causes of death. Their sensitivity and specificity compared favourably with that of data-derived algorithms based on logistic regression models. CONCLUSIONS: Cross-validation is crucial in preventing the over-fitting of the ANN models to the training data. Artificial neural network models are a potentially useful technique for classifying causes of death from verbal autopsies. Large training data sets are needed to improve the performance of data-derived algorithms, in particular ANN models.

Is there an interaction between human immunodeficiency virus and Plasmodium falciparum?

BACKGROUND: There is a potential for interaction between malaria and human immunodeficiency virus (HIV) infection. HIV infection might reduce immunity to malaria resulting in more frequent and severe infections; conversely malaria might enhance the progression of HIV infection to AIDS. In this paper we have reviewed some of the studies that have addressed this topic. METHODS: Studies identified by a MEDLINE search were systematically reviewed and the measures of association between the two infections were either abstracted or recalculated from the reported data. Inferences drawn from these studies and the biological plausibility of an interaction are discussed. RESULTS: The prevalence ratio (PR) of peripheral parasitaemia among HIV seropositive (HIVSP) individuals compared to HIV seronegative (HIVSN) individuals ranged from 0.72 to 0.94 in children and from 3.3 to 0.69 in adults. However, only one study showed a statistically significant difference between HIVSP and HIVSN groups (PR 3.3, 95% CI: 2.7-4.2). The rate ratio of non-severe malaria among HIVSP children compared to HIVSN children was 1.4 (95% CI: 0.99-2.0). Data from a trial of chemoprophylaxis during pregnancy suggested that placental malaria may predispose to perinatal transmission of HIV. Studies that have investigated the immune response to P. falciparum among HIVSP subjects have given variable results. CONCLUSION: There is no convincing evidence for an interaction between malaria and HIV with the possible exception of an interaction between placental malaria and HIV infection. Several studies, however, had potentials for bias and/or an inadequate sample size. There is a need for carefully designed studies to resolve whether mortality from severe malaria, in particular cerebral malaria, is increased in HIVSP subjects, whether malaria infection of the placenta increases the risk of vertical transmission of HIV, and whether malaria infection increases the progression of HIV infection to AIDS.

Diagnostic accuracy of physician review, expert algorithms and data-derived algorithms in adult verbal autopsies.

BACKGROUND: The verbal autopsy (VA) is used to collect information on cause-specific mortality from bereaved relatives. A cause of death may be assigned by physician review of the questionnaires, or by an algorithm. We compared the diagnostic accuracy of physician review, an expert algorithm, and data-derived algorithms. METHODS: Data were drawn from a multicentre validation study of 796 adult deaths that occurred in hospitals in Tanzania, Ethiopia, and Ghana. A 'gold standard' cause of death was assigned using hospital records and death certificates. The VA interviews were carried out by trained fieldworkers 1-21 months after the subject's death. A cause of death was assigned by physician review and an expert algorithm. Data-derived algorithms that most accurately estimated the cause-specific mortality fraction (CSMF) for each cause of death were identified using logistic regression. RESULTS: The most common causes of death were tuberculosis/AIDS (CSMF = 18.6%), malaria (CSMF = 10.7%), meningitis (CSMF = 8.3%), and cardiovascular disorders (CSMF = 8.2%). The CSMF obtained using physician review was within +/-20% of the gold standard value for 12 causes of death including the four common causes. The CSMF obtained using the expert algorithm was within +/-20% of the gold standard for eight causes of death, including tuberculosis/AIDS, malaria, and meningitis. The CSMF obtained using the data-derived algorithms was within +/-20% of the gold standard for seven causes of death, including tuberculosis/ AIDS, meningitis, and cardiovascular disorders. All three methods yielded a specificity of at least 80% for all causes of death, and a sensitivity of at least 80% for deaths due to injuries and rabies. CONCLUSIONS: For those settings where physician review is not feasible, expert and data-derived algorithms provide an alternative approach for assigning many causes of death. We recommend that the algorithms proposed herein are validated further.

Verbal autopsies for adult deaths: issues in their development and validation.

BACKGROUND: The verbal autopsy appears to be an attractive technique for the assessment of causes of adult death in settings where the proportion of people who die while under medical care is low. Verbal autopsies have been used extensively to assess causes of childhood deaths. The existing experience in verbal autopsies for adult deaths is limited mainly to maternal deaths. This paper aims to highlight the critical issues in verbal autopsies to assess causes of adult death which need further research. METHODS: This paper reviews the methods of verbal autopsy used in 35 published studies and discusses issues in the development of verbal autopsies, including mortality classification, design of questionnaires, interviewers, respondents, recall periods, procedures for deriving a diagnosis and the recording of single versus multiple causes of death. It also discusses issues in the validation of verbal autopsies, including the choice of reference diagnosis and the required sample size. RESULTS: The methodological approaches used in verbal autopsy studies have varied widely. Very few studies of the validity of verbal autopsies have been conducted. In these studies, the reported sensitivity and specificity varied widely between different causes of death and between studies. CONCLUSIONS: The information available is inadequate to draw firm conclusions on preferred methodological approaches for verbal autopsies for adult deaths. Before these tools are used more widely for adult deaths, further research is required to compare alternative methods and to evaluate the validity of this tool in a range of settings.

Effect of lead, mercury and cadmium on a sulphate-reducing bacterium.

A sulphate-reducing bacterial strain isolated from the south-west coast of India resembling Desulfosarcina in its physiology was tested for its behaviour towards HgCl(2), CdSO(4) and Pb(NO(3))(2). The order of toxicity to growth of these metal salts in a lactate-based medium at 50 microg ml(-1) concentrations was Cd>Pb>Hg and to respiration Pb>Cd>Hg. Inhibitory concentrations (viz. 100 microg ml(-1) of HgCl(2) and 200 microg ml(-1) of Pb(NO(3)(2)) had a stimulatory effect when the substrate was changed to acetate. With sodium acetate at 0.1% concentration, Hg and Pb had maximum stimulatory effect for growth and sulphide production. Experiments conducted directly with sediment slurries amended with lactate showed that all three metals (at levels below their inhibitory concentrations, i.e. 50 microg ml(-1) of metal salt for Cd and Hg and 100 microg ml(-1) for Pb) inhibited sulphate-reducing activity (SRA) with Pb decreasing the peak production by 68%. The order of toxicity in both lactate and acetate-amended slurry was Pb>Cd>Hg and Pb>Hg>Cd, respectively. With acetate, SRA in the presence of Cd and Hg was stimulated 110% and 27%, respectively. Pb inhibited SRA by 11%. There is a general reduction in the inhibition of sulphide production in slurries as compared with pure culture of the isolate.

Effects of a maternity waiting home on adverse maternal outcomes and the validity of antenatal risk screening.

OBJECTIVES: To evaluate the effect of a maternity waiting home (MWH) on adverse maternal outcomes and the validity of antenatal risk criteria in predicting dystocia. METHOD: A hospital-based cohort study was conducted at a district hospital in Zimbabwe. Information on the presence of antenatal risk factors, stay at an MWH, and mode and outcome of delivery was collected for each woman delivering at the hospital during 1989-1991. RESULTS: The risk of obstructed labor was 16 times higher for those not attending an MWH (n = 2915) than for those who did attend an MWH (n = 1573) (1 vs. 0.06%, P < 0.005). Among the non-users, 0.3% suffered a ruptured uterus compared with none of the MWH users. The presence of any one of the antenatal risk criteria used in Zimbabwe had a sensitivity of 78%, a specificity of 51% and positive predictive value of 25% for predicting dystocia. CONCLUSION: MWHs and antenatal risk screening are policy options for safe motherhood programs in settings where emergency obstetric services are not easily accessible.

Shifting from presumptive to test-based management of malaria - technical basis and implications for malaria control in Ghana.

The presumptive approach was the World Health Organisation (WHO) recommended to the management of malaria for many years and this was incorporated into syndromic guidelines such as the Integrated Management of Childhood Illnesses (IMCI). In early 2010 however, WHO issued revised treatment guidelines that call for a shift from the presumptive to the test-based approach. Practically, this implies that in all suspected cases, the diagnosis of uncomplicated malaria should be confirmed using rapid test before treatment is initiated. This revision effectively brings to an end an era of clinical practice that span several years. Its implementation has important implications for the health systems in malaria-endemic countries. On the basis of research in Ghana and other countries, and evidence from program work, the Ghana National Malaria Control Program has issued revised national treatment guidelines that call for implementation of test-based management of malaria in all cases, and across all age groups. This article reviews the evidence and the technical basis for the shift to test-based management and examines the implications for malaria control in Ghana.

Characterization of natural fibers and their application in bone grafting substitutes.

In the last decades, researchers have developed new materials to improve the quality of human life. Owing to the frequent occurrence of bone fractures, it is important to develop plate materials for the fixation of fractured bones. These plate materials have to be lightweight, compatible with human tissues and ought to allow stiffness. Natural fibers have the advantage that they are renewable resources and have marketing appeal. The Asian markets have been supplying natural fibers for many years, e.g., sisal, banana and roselle are common reinforcement in India. In this research, the fabrication of plate material from powdered natural fibers like sisal (Agave sisalana), banana (Musa sapientum) and roselle (Hibiscus sabdariffa), with bio-epoxy resin Grade 3554A and Hardner 3554B, using moulding method, is described. The present work deals with the prediction of flexural rigidity of the NFRP composite which is compared with that obtained using the ANSYS solution. They are found to be in good agreement. In this work, microstructure is scanned by the scanning electron microscope. The objective of this research was to utilize the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers. In the future, this plate material externally coated with calcium phosphate and hydroxyapatite (hybrid) composite can be used for inside fixation and also external fixation of fractured bones.

The role of antimalarial treatment in the elimination of malaria.

With declining transmission of malaria in several regions of the world and renewed interest in the elimination of malaria, strategies for malaria control using antimalarial drugs are being revisited. Drug-based strategies to reduce transmission of malaria need to target the asymptomatic carriers of infection. Drugs that are effective against gametocytes are few in number, but it may be possible to reduce gametocyte production by killing the asexual stages, for which more drugs are available. Drugs for use in large-scale programmes must be safe and tolerable. Strategies include improving access to treatment for malaria with an efficacious drug, intermittent-treatment programmes, and mass drug administration, with and without screening for malaria. Recent proposals have targeted high-risk groups for interventions. None of the strategies has been rigorously tested with appropriate control groups for comparison. Because of the lack of field evidence, modelling has been used. Models have shown, first, that for long-lasting effects, drug administration programmes should be linked with vector control, and second, that if elimination is the aim, programmes are likely to be more successful when applied to smaller populations of a few thousand or less. In order to sustain the gains following the scaling up of vector control and use of artemisinin combination therapies (ACTs), strategies that use antimalarials effectively need to be devised and evidence generated for the most cost-efficient way forward.