High Endemic Settings Research Articles

Diagnostic Advances in Childhood Tuberculosis-Improving Specimen Collection and Yield of Microbiological Diagnosis for Intrathoracic Tuberculosis.

There is no microbiological gold standard for childhood tuberculosis (TB) diagnosis. The paucibacillary nature of the disease, challenges in sample collection in young children, and the limitations of currently available microbiological tests restrict microbiological confirmation of intrathoracic TB to the minority of children. Recent WHO guidelines recommend the use of novel rapid molecular assays as initial diagnostic tests for TB and endorse alternative sample collection methods for children. However, the uptake of these tools in high-endemic settings remains low. In this review, we appraise historic and new microbiological tests and sample collection techniques that can be used for the diagnosis of intrathoracic TB in children. We explore challenges and possible ways to improve diagnostic yield despite limitations, and identify research gaps to address in order to improve the microbiological diagnosis of intrathoracic TB in children.

Clinical and epidemiological trends in childhood leprosy: A 20-year retrospective analysis from a tertiary care hospital in Jammu, North India.

Background Slightly more than half the total number of childhood leprosy cases worldwide are from India. Aim To analyze the clinical and epidemiological trends of childhood leprosy over 20 years in a tertiary care hospital. Methods We retrieved the medical records of all children less than 15 years of age registered in the leprosy clinic between April 1998 and March 2018. We tabulated and analyzed data pertaining to demographic details along with clinical findings such as cutaneous lesions, nerves involved, sensory loss, deformities, reactions, smear status, histopathology and treatment. Results Out of total 1548 leprosy cases registered during the study period, 55 (3.55%) cases of childhood leprosy were diagnosed. Thirty five (63.6%) children were in the age group of 11-15 years and 83.7% were migrants from other states. Thirteen (23.6%) children reported contact with a diagnosed case of leprosy, mainly in close contacts. Fifty three (96.4%) children presented with cutaneous lesions while 2 (3.6%) had pure neural involvement. Borderline tuberculoid leprosy was the most common clinical presentation in 27 (49.1%) followed by borderline lepromatous leprosy in 11 (18%). Thickened peripheral nerve trunks were detected in 42 (76.4%), most commonly the ulnar nerve. Reactional episodes occurred in 12 (21.8%) cases (Type 1 reaction, 10 (18.2%); Type 2 reaction, 2 (3.6%)). Grade 2 disability was detected in 4 (7.3%). Multidrug therapy was started in all patients, multibacillary (MB) regimen in 42 (76.3%) patients and paucibacillary (PB) regimen in 13 (23.7%). Twenty five (45.4%) children defaulted from the treatment. On comparing the data of 2008-18 with that of the previous decade (1998-2007), there was a higher proportion of migrant cases as compared to local cases (3:1-11:1) and MB cases as compared to PB cases (2:1-6:1). The proportion of treatment defaulters declined from 60% to 36%. Limitations Relapse rate could not be calculated due to inadequate follow-up period. As it is a hospital-based retrospective study with no active surveys, these findings may not reflect trends in the community. Conclusion Childhood leprosy continues to be a significant problem. There is a clear need to strengthen early detection, treatment and regular follow-up of these cases in both high and low endemic settings.

Spatial distribution and risk factors for human cysticercosis in Colombia

BackgroundCysticercosis is a zoonotic neglected tropical disease (NTD) that affects humans and pigs following the ingestion of Taenia solium eggs. Human cysticercosis poses a substantial public health burden in endemic countries. The World Health Organization (WHO) aims to target high-endemicity settings with enhanced interventions in 17 countries by 2030. Between 2008 and 2010, Colombia undertook a national baseline serosurvey of unprecedented scale, which led to an estimated seroprevalence of T. solium cysticercus antibodies among the general population of 8.6%. Here, we use contemporary geostatistical approaches to analyse this unique dataset with the aim of understanding the spatial distribution and risk factors associated with human cysticercosis in Colombia to inform how best to target intervention strategies.MethodsWe used a geostatistical model to estimate individual and household risk factors associated with seropositivity to T. solium cysticercus antibodies from 29,253 people from 133 municipalities in Colombia. We used both independent and spatially structured random effects at neighbourhood/village and municipality levels to account for potential clustering of exposure to T. solium. We present estimates of the distribution and residual correlation of seropositivity at the municipality level.ResultsHigh seroprevalence was identified in municipalities located in the north and south of Colombia, with spatial correlation in seropositivity estimated up to approximately 140 km. Statistically significant risk factors associated with seropositivity to T. solium cysticercus were related to age, sex, educational level, socioeconomic status, use of rainwater, consumption of partially cooked/raw pork meat and possession of dogs.ConclusionsIn Colombia, the distribution of human cysticercosis is influenced by socioeconomic considerations, education and environmental factors related to the spread of T. solium eggs. This information can be used to tailor national intervention strategies, such as targeting spatial hotspots and more highly exposed groups, including displaced people and women. Large-scale seroprevalence surveys accompanied by geospatial mapping are an essential step towards reaching the WHO’s 2021‒2030 NTD roadmap targets.Graphical

Malaria awareness of adults in high, moderate and low transmission settings: A cross-sectional study in rural East Nusa Tenggara Province, Indonesia.

The 2009 Indonesian roadmap to malaria elimination indicated that the nation had been progressing towards achieving malaria elimination by 2030. Currently, most of the districts in the western part of Indonesia have eliminated malaria; however, none of the districts in the East Nusa Tenggara Province (ENTP) have met these set targets. This study aimed to investigate the status of malaria awareness of rural adults in the ENTP. A community-based cross-sectional study was conducted between October and December 2019 in high, moderate, and low malaria-endemic settings (MESs) in the ENTP. After obtaining informed consent, data were collected using an interviewer-administered structure questionnaire among 1503 participants recruited by a multi-stage cluster sampling method. A malaria awareness index was developed based on ten questions. A binary logistic regression method was applied to investigate the significance of any association between malaria awareness and the different MESs. The participation rate of the study was 99.5%. Of this number, 51.4% were female and 45.5% had completed primary education. The malaria awareness index was significantly low (48.8%, 95% confidence interval [CI]: 45.2-52.4). Malaria awareness of rural adults residing in low endemic settings was two times higher than for those living in high endemic settings (adjusted odds ratio [AOR]: 2.41, 95% CI: 1.81-3.21) and the basic malaria knowledge of participants living in low malaria-endemic settings was almost four times higher than that in high endemic settings (AOR: 3.75, 95% CI: 2.75-5.11). Of the total participants, 81.3% (95% CI: 79.1-83.5) were aware that malaria could be prevented and 75.1% (95% CI: 72.6-77.6) knew at least one prevention measure. Overall, the awareness of fever as the main symptom of malaria, mosquito bites as the transmission mode of malaria, and seeking treatment within 24 hours of suffering from malaria was poor at 37.9% (95% CI: 33.9-41.9), 59.1% (95% CI: 55.9-62.3), and 46.0% (95% CI: 42.3-49.7), respectively. The poor level of awareness was significantly different amongst the three MESs, with the lowest levels of awareness in the high endemic setting. Malaria awareness of rural adults needs to be improved to address Indonesia's national roadmap for malaria elimination. Results indicated that public health programs at a local government level should incorporate the malaria awareness index in their key strategic intervention to address malaria awareness.

High Acquisition Rate of Gram-Negative Multi-Drug Resistant Organism Colonization During Hospitalization: A Perspective from a High Endemic Setting.

ObjectiveThe aim of the study was to compare the rate of gram-negative multi-drug resistant organism (GN-MDRO) colonization at admission and during hospitalization and to describe the strains and antibiotic resistance genes acquired during hospitalization.MethodsRectal swabs were collected from patients hospitalized at the National Trauma Center (NTC), Mongolia, at the time of admission and after 14 days of hospitalization as has been detailed on our previous study. GN-MDRO antibiotic resistance was determined using EUCAST standards, and resistance genes were detected using multiplex PCR.ResultsA total of 158 patients were screened, and baseline colonization rate at admission was 29.1% (46/158). The rate went up to 69.9% (110/158) after 14 days of hospitalization (p<0.001). Of all participants, 74 patients (46.8%) screened GN-MDRO negative at admission acquired colonization by day 14. Other 36 patients (22.8%) maintained colonization that was screened positive at both time points. Only 38 patients (24.0%) remained free of GN-MDRO during hospitalization. There was a difference in GN-MDRO acquisition between these groups. Patients who were negative at admission acquired up to 3 GN-MDRO species, and there were 10 different species isolated. Reversely, patients who were screened positive at both time points had fairly homogenous isolates; up to 5 species of Enterobacterales were identified at admission and day 14 hospitalization. Overall, Enterobacterales were the dominant colonizers (61.4%, 97/158), and all Enterobacterales were resistant to cefotaxime as CTX-M resistance was our inclusion criteria.ConclusionGN-MDRO baseline colonization rate on admission was high and, alarmingly, doubled during hospitalization in the study area. Enterobacterales was the predominant colonizer and was highly resistant to 3rd generation cephalosporin. This data supports a need for an improved infection control policy including routine surveillance of the GN-MDROs and improved antibiotic stewardship program.

PLASMABLASTIC LYMPHOMA: ORAL VS EXTRAORAL

<h3>Background</h3> Originally thought to be exclusive to the oral cavity in human immunodeficiency virus (HIV)-infected persons, plasmablastic lymphoma (PBL) is increasingly described extraorally, and in non-HIV-infected patients. Demographic data are often dependent on case reports, case series, and systemic reviews. <h3>Objective</h3> This is an epidemiological, morphological, and immunological comparison of oral and extraoral PBLs in a high HIV endemic setting. <h3>Methods</h3> This retrospective study of extraoral and oral PBLs diagnosed over a 5-year period analyzed patients' age, sex, HIV status, and tumor site. Histologic diagnosis was confirmed and tumors were assessed immunohistochemically with CD45 (LCA), CD20, CD79a, PAX5, CD138, MUM1, BLIMP1, VS38c, Ki-67, BCL6, CD10, and HHV8 using the manufacturers' protocols. The presence of Epstein-Barr virus (EBV) was assessed by chromogenic in situ hybridization. Ethics clearance: M10750. <h3>Results</h3> There were 46 extraoral and 54 oral PBLs. Patient age ranged from 9 to 59 years (extraoral) and from 22 to 78 years (oral). In known HIV cases, 95% of extraoral and 97% of oral cases were HIV-positive. None had systemic disease at presentation. The male:female ratio was 1.4:1 for extraoral and 2.7:1 for oral PBLs. The favored extraoral and oral sites were the anus (28%) and maxilla (29%). Immunohistochemical profiles recapitulated that previously reported, except for CD45 expression, which was higher (85.7% extraoral, 97% oral). EBV was positive by in situ hybridization in 96% of PBLs, 93% of extraoral PBLs, and all oral PBLs. <h3>Conclusions</h3> Extraoral and oral PBLs are identical in sex and age distribution, HIV status, morphological appearance, immunophenotypic profile, and EBV association. PBL should be regarded as the same tumor irrespective of oral or extraoral site of origin.

Universal admission screening: a potential game-changer in hospitals with high prevalence of MRSA

Despite the perception that meticillin-resistant Staphylococcus aureus (MRSA) is now under control in high-income countries, global prevalence remains high, even increasing in some regions. Universal admission screening and decolonization has been instituted in some hospitals to attempt control but the practice remains controversial. In 2014, Mater Dei Hospital in Malta introduced a universal admission screening policy, utilizing a novel, centralized and customized approach to achieve high compliance and low cost. Admissions are screened nasally by designated staff using chromogenic media, irrespective of risk factors. Carriers are decolonized without concurrent isolation or contact precautions. In this study, longitudinal, quasi-experimental evaluation was undertaken using time series analysis to analyse the impact of the intervention on the proportion of MRSA among clinical S.aureus isolates (%MRSA) and incidence per 1000 bed-days. A cost-utility analysis was also attempted to identify approximate quality-adjusted life years (QALYs) gained. A transfer function model approach concluded that the intervention had a significant effect on both %MRSA and incidence. Six years following its introduction, the screening programme had led to an overall 43% long-term reduction in %MRSA from pre-screening levels [R2=0.687; Bayesian information criterion (BIC)=4.063], translating to a decrease in incidence of approximately 0.56 cases/1000 bed-days (R2=0.633, BIC=-3.063). No correlation was identified with consumption of antibiotics or alcohol hand rub. The annual cost-benefit of the programme was calculated at €1058 per QALY gain per year. The universal admission screening and decolonization intervention was successful and cost-effective in this high-endemicity setting. It facilitated improvement in the prevalence of MRSA, achieving reduction levels rarely reported by Mediterranean hospitals.

Functional and Activation Profiles of Mucosal-Associated Invariant T Cells in Patients With Tuberculosis and HIV in a High Endemic Setting.

Background: MAIT cells are non-classically restricted T lymphocytes that recognize and rapidly respond to microbial metabolites or cytokines and have the capacity to kill bacteria-infected cells. Circulating MAIT cell numbers generally decrease in patients with active TB and HIV infection, but findings regarding functional changes differ.Methods: We conducted a cross-sectional study on the effect of HIV, TB, and HIV-associated TB (HIV-TB) on MAIT cell frequencies, activation and functional profile in a high TB endemic setting in South Africa. Blood was collected from (i) healthy controls (HC, n = 26), 24 of whom had LTBI, (ii) individuals with active TB (aTB, n = 36), (iii) individuals with HIV infection (HIV, n = 50), 37 of whom had LTBI, and (iv) individuals with HIV-associated TB (HIV-TB, n = 26). All TB participants were newly diagnosed and sampled before treatment, additional samples were also collected from 18 participants in the aTB group after 10 weeks of TB treatment. Peripheral blood mononuclear cells (PBMC) stimulated with BCG-expressing GFP (BCG-GFP) and heat-killed (HK) Mycobacterium tuberculosis (M.tb) were analyzed using flow cytometry. MAIT cells were defined as CD3+ CD161+ Vα7.2+ T cells.Results: Circulating MAIT cell frequencies were depleted in individuals with HIV infection (p = 0.009). MAIT cells showed reduced CD107a expression in aTB (p = 0.006), and reduced IFNγ expression in aTB (p < 0.001) and in HIV-TB (p < 0.001) in response to BCG-GFP stimulation. This functional impairment was coupled with a significant increase in activation (defined by HLA-DR expression) in resting MAIT cells from HIV (p < 0.001), aTB (p = 0.019), and HIV-TB (p = 0.005) patients, and higher HLA-DR expression in MAIT cells expressing IFNγ in aTB (p = 0.009) and HIV-TB (p = 0.002) after stimulation with BCG-GFP and HK-M.tb. After 10 weeks of TB treatment, there was reversion in the observed functional impairment in total MAIT cells, with increases in CD107a (p = 0.020) and IFNγ (p = 0.010) expression.Conclusions: Frequencies and functional profile of MAIT cells in response to mycobacterial stimulation are significantly decreased in HIV infected persons, active TB and HIV-associated TB, with a concomitant increase in MAIT cell activation. These alterations may reduce the capacity of MAIT cells to play a protective role in the immune response to these two pathogens.

Dynamics of intestinal multidrug-resistant bacteria colonisation contracted by visitors to a high-endemic setting: a prospective, daily, real-time sampling study

SummaryBackgroundAntimicrobial resistance is highly prevalent in low-income and middle-income countries. International travel contributes substantially to the global spread of intestinal multidrug-resistant Gram-negative bacteria. Hundreds of millions of annual visitors to low-income and middle-income countries are all exposed to intestinal multidrug-resistant Gram-negative bacteria resulting in 30–70% of them being colonised at their return. The colonisation process in high-exposure environments is poorly documented because data have only been derived from before travel and after travel sampling. We characterised colonisation dynamics by exploring daily stool samples while visiting a low-income and middle-income countries.MethodsIn this prospective, daily, real-time sampling study 20 European visitors to Laos volunteered to provide daily stool samples and completed daily questionnaires for 22 days. Samples were initially assessed at Mahosot Hospital, Vientiane, Laos, for acquisition of extended-spectrum β-lactamase-producing (ESBL) Gram-negative bacteria followed by whole-genome sequencing of isolates at MicrobesNG, University of Birmingham, Birmingham, UK. The primary outcome of the study was to obtain data on the dynamics of intestinal multidrug-resistant bacteria acquisition.FindingsBetween Sept 18 and Sept 20, 2015, 23 volunteers were recruited, of whom 20 (87%) European volunteers were included in the final study population. Although colonisation rates were 70% at the end of the study, daily sampling revealed that all participants had acquired ESBL-producing Gram-negative bacteria at some point during the study period; the colonisation status varied day by day. Whole-genome sequencing analysis ascribed the transient pattern of colonisation to sequential acquisition of new strains, resulting in a loss of detectable colonisation by the initial multidrug-resistant Gram-negative strains. 19 (95%) participants acquired two to seven strains. Of the 83 unique strains identified (53 Escherichia coli, 10 Klebsiella spp, and 20 other ESBL-producing Gram-negative bacteria), some were shared by as many as four (20%) participants.InterpretationTo our knowledge, this is the first study to characterise in real-time the dynamics of acquiring multidrug-resistant Gram-negative bacterial colonisation during travel. Our data show multiple transient colonisation events indicative of constant microbial competition and suggest that travellers are exposed to a greater burden of multidrug-resistant bacteria than previously thought. The data emphasise the need for preventing travellers' diarrhoea and limiting antibiotic use, addressing the two major factors predisposing colonisation.FundingThe Finnish Governmental Subsidy for Health Science Research, The Scandinavian Society for Antimicrobial Chemotherapy, the Sigrid Jusélius Foundation, Biotechnology and Biological Sciences Research Council; Wellcome Trust, Medical Research Council; The Royal Society; Joint Programming Initiative on Antimicrobial Resistance, and European Research Council.

The epidemiology and detectability of asymptomatic Plasmodium vivax and Plasmodium falciparum infections in low, moderate and high transmission settings in Ethiopia

BackgroundAs countries move to malaria elimination, detecting and targeting asymptomatic malaria infections might be needed. Here, the epidemiology and detectability of asymptomatic Plasmodium falciparum and Plasmodium vivax infections were investigated in different transmission settings in Ethiopia.Method:A total of 1093 dried blood spot (DBS) samples were collected from afebrile and apparently healthy individuals across ten study sites in Ethiopia from 2016 to 2020. Of these, 862 were from community and 231 from school based cross-sectional surveys. Malaria infection status was determined by microscopy or rapid diagnostics tests (RDT) and 18S rRNA-based nested PCR (nPCR). The annual parasite index (API) was used to classify endemicity as low (API > 0 and < 5), moderate (API ≥ 5 and < 100) and high transmission (API ≥ 100) and detectability of infections was assessed in these settings.ResultsIn community surveys, the overall prevalence of asymptomatic Plasmodium infections by microscopy/RDT, nPCR and all methods combined was 12.2% (105/860), 21.6% (183/846) and 24.1% (208/862), respectively. The proportion of nPCR positive infections that was detectable by microscopy/RDT was 48.7% (73/150) for P. falciparum and 4.6% (2/44) for P. vivax. Compared to low transmission settings, the likelihood of detecting infections by microscopy/RDT was increased in moderate (Adjusted odds ratio [AOR]: 3.4; 95% confidence interval [95% CI] 1.6–7.2, P = 0.002) and high endemic settings (AOR = 5.1; 95% CI 2.6–9.9, P < 0.001). After adjustment for site and correlation between observations from the same survey, the likelihood of detecting asymptomatic infections by microscopy/RDT (AOR per year increase = 0.95, 95% CI 0.9–1.0, P = 0.013) declined with age.ConclusionsConventional diagnostics missed nearly half of the asymptomatic Plasmodium reservoir detected by nPCR. The detectability of infections was particularly low in older age groups and low transmission settings. These findings highlight the need for sensitive diagnostic tools to detect the entire parasite reservoir and potential infection transmitters.

Allelic diversity of MSP1 and MSP2 repeat loci correlate with levels of malaria endemicity in Senegal and Nigerian populations

BackgroundCharacterizing the genetic diversity of malaria parasite populations in different endemic settings (from low to high) could be helpful in determining the effectiveness of malaria interventions. This study compared Plasmodium falciparum parasite population diversity from two sites with low (pre-elimination) and high transmission in Senegal and Nigeria, respectively.MethodsParasite genomic DNA was extracted from 187 dried blood spot collected from confirmed uncomplicated P. falciparum malaria infected patients in Senegal (94) and Nigeria (93). Allelic polymorphism at merozoite surface protein 1 (msp1) and merozoite surface protein- 2 (msp2) genes were assessed by nested PCR.ResultsThe most frequent msp1 and msp2 allelic families are the K1 and IC3D7 allelotypes in both Senegal and Nigeria. Multiplicity of infection (MOI) of greater that 1 and thus complex infections was common in both study sites in Senegal (Thies:1.51/2.53; Kedougou:2.2/2.0 for msp1/2) than in Nigeria (Gbagada: 1.39/1.96; Oredo: 1.35/1.75]). The heterozygosity of msp1 gene was higher in P. falciparum isolates from Senegal (Thies: 0.62; Kedougou: 0.53) than isolates from Nigeria (Gbagada: 0.55; Oredo: 0.50). In Senegal, K1 alleles was associated with heavy than with moderate parasite density. Meanwhile, equal proportions of K1 were observed in both heavy and moderate infection types in Nigeria. The IC3D7 subtype allele of the msp2 family was the most frequent in heavily parasitaemic individuals from both countries than in the moderately infected participants.ConclusionThe unexpectedly low genetic diversity of infections high endemic Nigerian setting compared to the low endemic settings in Senegal is suggestive of possible epidemic outbreak in Nigeria.

Effect of pregnancy and HIV infection on detection of latent TB infection by Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube assay among women living in a high TB and HIV burden setting

ObjectiveTo investigate the effect of pregnancy and Human immunodeficiency virus (HIV) infection on detection performances of tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFTGIT) for the diagnosis of latent tuberculosis infection (LTBI) among women living in high TB and HIV endemic setting. MethodA cross-sectional study was conducted among women with and without pregnancy and HIV infection. Three-hundred twenty women were enrolled in this study and were diagnosed using TST and QFTGIT for the detection of LTBI. ResultsOverall prevalence of LTBI among the enrolled women was 55.6%, 46.3% and 51.1% as determined by TST, QFTGIT and concordant TST/QFTGIT results, respectively. Our study revealed that pregnancy or HIV infection reduced the rate of detection of LTBI by TST and QFTGIT tests, with the utmost effect observed in HIV-positive pregnant women. Additionally, we observed that the concordance between TST and QFTGIT among women increased with the presence of pregnancy and/or HIV infection. A history of contact with TB patients was significantly associated with positivity of TST and QFTGIT. ConclusionThis study demonstrated that both pregnancy and HIV infection profoundly affected the detection performance of TST and QFTGIT, which may be associated with immunosuppression of anti-mycobacterial immunity in women with pregnancy and/or HIV infection.

Determinants of Plasmodium falciparum multiplicity of infection and genetic diversity in Burkina Faso

BackgroundInvestigating malaria transmission dynamics is essential to inform policy decision making. Whether multiplicity of infection (MOI) dynamic from individual infections could be a reliable malaria metric in high transmission settings with marked variation in seasons of malaria transmission has been poorly assessed. This study aimed at investigating factors driving Plasmodium falciparum MOI and genetic diversity in a hyperendemic area of Burkina Faso.MethodsBlood samples collected from a pharmacovigilance trial were used for polymerase chain reaction genotyping of the merozoite surface proteins 1 and 2. MOI was defined as the number of distinct parasite genotypes co-existing within a particular infection. Monthly rainfall data were obtained from satellite data of the Global Precipitation Measurement Database while monthly malaria incidence aggregated data were extracted from District Health Information Software 2 medical data of the Center-West health regional direction.ResultsIn the study area, infected people harboured an average of 2.732 (± 0.056) different parasite genotypes. A significant correlation between the monthly MOI and the monthly malaria incidence was observed, suggesting that MOI could be a good predictor of transmission intensity. A strong effect of season on MOI was observed, with infected patients harbouring higher number of parasite genotypes during the rainy season as compared to the dry season. There was a negative relationship between MOI and host age. In addition, MOI decreased with increasing parasite densities, suggesting that there was a within-host competition among co-infecting genetically distinct P. falciparum variants. Each allelic family of the msp1 and msp2 genes was present all year round with no significant monthly fluctuation.ConclusionsIn high malaria endemic settings with marked variation in seasons of malaria transmission, MOI represents an appropriate malaria metric which provides useful information about the longitudinal changes in malaria transmission in a given area. Besides transmission season, patient age and parasite density are important factors to consider for better understanding of variations in MOI. All allelic families of msp1 and msp2 genes were found in both dry and rainy season. The approach offers the opportunity of translating genotyping data into relevant epidemiological information for malaria control.

Magnetic bead flocculation test: Improving the diagnosis of tuberculous meningitis (TBM) in low-resource settings

BackgroundDespite several recent advances in detection techniques, there is still an unmet need for simple tests for the diagnosis of tuberculous meningitis (TBM). Therefore, in an effort towards developing a simple and rapid diagnostic test for resource-poor settings, we designed an assay in which magnetic bead flocculation test (MBF) was used to detect the amplified DNA. Multi-targeted (using two multicopy gene targets IS6110 and IS1081) loop-mediated isothermal amplification (MLAMP) was used for amplification. MethodsMLAMP-MBF assay was performed on CSF samples of 600 patients, out of which 120 were definite TBM (culture confirmed), 280 were probable TBM and 200 were non-TB controls, based on Marais's criteria. The performance of assay was evaluated by comparing the result of definite TBM with culture and that of probable TBM with composite reference standard consisting of clinical, microbiological(smear/culture) and radiological parameters. ResultsThe overall sensitivity of MLAMP-MBF (using any of the two gene targets) was 89.5% and specificity was 100%. The sensitivity was 96.6% (116/120) in diagnosing definite TBM and 86.4% (242/280) in diagnosing probable TBM. The sensitivity of IS1081 was 88% and that of IS6110 was 83% in diagnosing TBM. Specificity of both the gene targets was 100%. There were 20 cases positive only by IS1081 LAMP and 6 cases positive only by IS6110; thus 26 of 400 (6.5%) TBM cases could be additionally detected following multi-targeted approach. ConclusionMLAMP-MBF is a sensitive, robust, cost-effective and promising technique for diagnosis of TBM in low-resource high-endemic settings.

Investigating the Effect of Prompt Treatment on Malaria Prevalence in Children Aged below Five Years in Zambia: A Nested Case-Control Study in a Cross-Sectional Survey

Background. In a highly malaria endemic country like Zambia, prompt treatment of cases is known to reduce morbidity and mortality; however, it is not known whether it has a role as an effective prevention strategy because of the presence of asymptomatic chronic carriers who do not seek treatment and maintain the reservoirs of infection in the population. This study investigated the role of treatment of malaria cases as a prevention strategy in low, moderate, and high endemic settings. Methods. A nested case-control design was employed using datasets from a large countrywide national Malaria Indicator Survey of 2015. Self-reported malaria cases (n = 209) who took treatment in the two weeks preceding the survey were matched with controls (n = 511) who did not report malaria and did not take treatment during the same period using nearest neighbour propensity score matching for age, sex, and district. The data were analysed using conditional logistic regression in STATA version 15.1. Results. The malaria cases were more likely to be from rural areas (p=0.001), poorest households (p=0.049), and who lived in improvised housing structures (p=0.004) compared with the controls. Data from low and moderate malaria endemic areas did not have sufficient cases for the analysis to proceed; however, data from high endemic areas showed borderline evidence (p=0.054) that prompt treatment reduces the risk of malaria by almost half in the short-term aOR 0.057 (95% CI 0.32–1.01). Conclusion. We found borderline evidence which suggests that prompt treatment of malaria cases even in high endemic areas has potential to reduce the risk of malaria by almost half in the short term.

Multicentric validation of indigenous molecular test Truenat™ MTB for detection of Mycobacterium tuberculosis in sputum samples from presumptive pulmonary tuberculosis patients in comparison with reference standards.

Background & objectives:Early case detection is essential to interrupt transmission and to prevent further spread of tuberculosis (TB) in high endemic settings. Nucleic acid amplification tests (NAATs) with visual read-outs are ideal as point-of-care tests. Truenat™ MTB is an indigenous chip-based NAAT for detection of Mycobacterium tuberculosis, which involves extraction of DNA and real-time polymerase chain reaction (PCR) using portable, automated, battery-operated instruments. The current multicentric study was aimed to evaluate Truenat for detection of MTB in sputum samples obtained from patients with presumptive pulmonary TB with reference to culture as gold standard and Xpert as a comparator.Methods:The study was conducted at four sites, namely ICMR-National Institute for Research in Tuberculosis, Chennai; All India Institute of Medical Sciences, New Delhi; ICMR-National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra; and National Institute of TB and Respiratory Diseases, New Delhi. Patients suspected to have TB were screened for eligibility. Two sputum samples were collected from each patient. Tests included smear, Xpert and Truenat directly from the sputum sample and culture by Lowenstein-Jensen (L-J) medium and MGIT960 from decontaminated pellets. Sample used for Truenat assay was coded. Resolution of Truenat false positives was done using an in-house PCR with TRC4 primers.Results:The study enrolled 2419 presumptive TB patients after screening 2465 patients, and 3541 sputum samples were collected from the enrolled patients. Results of 2623 samples were available for analysis. Truenat showed a positivity rate of 48.5 per cent as compared to 37.0 per cent by Xpert. The sensitivities of Truenat and Xpert were was 88.3 and 79.7 per cent, respectively in comparison with culture.Interpretation & conclusions:Truenat MTB identified more positives among culture-confirmed samples than Xpert and had higher sensitivity. In addition, other advantageous operational features of Truenat MTB were identified which would be useful in field settings.

Pathogenic characteristics of Pseudomonas aeruginosa bacteraemia isolates in a high-endemicity setting for ST175 and ST235 high-risk clones.

Multidrug-resistant (MDR) Pseudomonas aeruginosa represents a major clinical concern. The interplay between antimicrobial resistance and virulence of P. aeruginosa was investigated in in vitro and in vivo studies. Thirty-eight well-characterized (21 MDR and 17 non-MDR) P. aeruginosa strains from patients with bacteraemia were analysed. Resistance phenotype, carbapenemase production, clonal relatedness, type III secretion system genotype, O-antigen serotype, cytotoxicity (ability to lyse cells) on A549 cells, and virulence (lethality in nematodes) in a Caenorhabditis elegans model were investigated. MDR strains showed lower cytotoxicity (35.4 ± 21.30% vs. 45.0 ± 18.78 %; P = 0.044) and virulence (66.7% vs. 100%; P = 0.011) than non-MDR strains. However, the pathogenicity of MDR high-risk clones varied broadly, with ST235 and ST175 clones being the most and least cytotoxic (51.8 ± 10.59% vs. 11.0 ± 1.25%; P < 0.0001) and virulent ([100% vs. 73.1; P = 0.075] and [0% vs. 93.9%; P < 0.0001], respectively). The pathogenicity of the ST235 clone was similar to that of non-MDR strains, and its ability to lyse cells and high virulence were related with the exoU-positive genotype. Furthermore, the O11 serotype was more frequent among the ST235 clone and exoU-positive genotype strains and was also essential for the pathogenicity of P. aeruginosa. Our data suggest that the pathogenicity of MDR high-risk clones is the result not only of the resistance phenotype but also of the virulence genotype. These findings have implications for the clinical management of patients and infection control programmes.

Clinical Evaluation of a Multiplex PCR for the Detection of Salmonella enterica Serovars Typhi and Paratyphi A from Blood Specimens in a High-Endemic Setting

.Enteric fever is a major public health concern in endemic areas, particularly in infrastructure-limited countries where Salmonella Paratyphi A has emerged in increasing proportion of cases. We aimed to evaluate a method to detect Salmonella Typhi (S. Typhi) and Salmonella Paratyphi A (S. Paratyphi A) in febrile patients in Bangladesh. We conducted a prospective study enrolling patients with fever > 38°C admitted to two large urban hospitals and two outpatient clinics located in Dhaka, Bangladesh. We developed and evaluated a method combining short culture with a new molecular assay to simultaneously detect and differentiate S. Typhi and S. Paratyphi A from other Salmonella directly from 2 to 4 mL of whole blood in febrile patients (n = 680). A total of 680 cases were enrolled from the four participating sites. An increase in the detection rate (+38.8%) in S. Typhi and S. Paratyphi A was observed with a multiplex polymerase chain reaction (PCR) assay, and absence of non-typhoidal Salmonella detection was reported. All 45 healthy controls were culture and PCR negative, generating an estimated 92.9% of specificity on clinical samples. When clinical performance was assessed in the absence of blood volume prioritization for testing, a latent class model estimates clinical performance ≥ 95% in sensitivity and specificity with likelihood ratio (LR) LR+ > 10 and LR− < 0.1 for the multiplex PCR assay. The alternative method to blood culture we developed may be useful alone or in combination with culture or serological tests for epidemiological studies in high disease burden settings and should be considered as secondary endpoint test for future vaccine trials.

Polymorphisms in CARD8 and NLRP3 are associated with extrapulmonary TB and poor clinical outcome in active TB in Ethiopia

Innate immunity is a first line defense against Mycobacterium tuberculosis infection where inflammasome activation and secretion of the pro-inflammatory cytokine IL-1beta, plays a major role. Thus, genetic polymorphisms in innate immunity-related genes such as CARD8 and NLRP3 may contribute to the understanding of why most exposed individuals do not develop infection. Our aim was to investigate the association between polymorphisms in CARD8 and NLRP3 and active tuberculosis (TB) as well as their relationship to treatment outcome in a high-endemic setting for TB. Polymorphisms in CARD8 (C10X) and NLRP3 (Q705K) were analysed in 1190 TB patients and 1990 healthy donors (HD). There was a significant association between homozygotes in the CARD8 polymorphism and extrapulmonary TB (EPTB), which was not the case for pulmonary TB or HDs. Among TB-patients, there was an association between poor treatment outcome and the NLRP3 (Q705K) polymorphism. Our study shows that inflammasome polymorphisms are associated with EPTB and poor clinical outcome in active TB in Ethiopia. The practical implications and determining causal relationships on a mechanistic level needs further study.

Perceptions of Tuberculosis Among Individuals Born in a High-Endemic Setting, Now Living in a Low-Endemic Setting.

Of all individuals diagnosed with tuberculosis (TB) in Sweden 2015 were 90% born in other countries. Early diagnosis and treatment is essential to avoid TB transmission. Lack of knowledge about TB and anticipated negative social consequences have proved to be significant contributing factors to delay in seeking health care. This study aimed to understand the perception of TB among people originating from a high-endemic region, currently living in a low-endemic region. A qualitative study design, with male and female participants from a high-endemic region divided into focus groups. A semi-structured interview guide was used to elicit their perceptions of TB. A qualitative content analysis was performed on the recorded material from the interviews. The informants noted that their attitude towards individuals with TB had changed, previously they had felt prejudiced towards them whereas now they felt supportive. It seems possible to diminish TB stigma by ensuring suitable health care is available in combination with correct information about transmission, infectiousness and treatment.