ABSTRACT
HIV/AIDS is a leading cause of disease burden in sub-Saharan Africa. Existing evidence has demonstrated that there is substantial local variation in the prevalence of HIV; however, subnational variation has not been investigated at a high spatial resolution across the continent. Here we explore within-country variation at a 5 × 5-km resolution in sub-Saharan Africa by estimating the prevalence of HIV among adults (aged 15-49 years) and the corresponding number of people living with HIV from 2000 to 2017. Our analysis reveals substantial within-country variation in the prevalence of HIV throughout sub-Saharan Africa and local differences in both the direction and rate of change in HIV prevalence between 2000 and 2017, highlighting the degree to which important local differences are masked when examining trends at the country level. These fine-scale estimates of HIV prevalence across space and time provide an important tool for precisely targeting the interventions that are necessary to bringing HIV infections under control in sub-Saharan Africa.
Subject(s)
Geographic Mapping , HIV Infections/epidemiology , Adolescent , Adult , Africa South of the Sahara/epidemiology , Female , HIV Infections/prevention & control , Humans , Male , Middle Aged , Prevalence , Public Health/statistics & numerical data , Public Health/trends , Young AdultABSTRACT
Insufficient growth during childhood is associated with poor health outcomes and an increased risk of death. Between 2000 and 2015, nearly all African countries demonstrated improvements for children under 5 years old for stunting, wasting, and underweight, the core components of child growth failure. Here we show that striking subnational heterogeneity in levels and trends of child growth remains. If current rates of progress are sustained, many areas of Africa will meet the World Health Organization Global Targets 2025 to improve maternal, infant and young child nutrition, but high levels of growth failure will persist across the Sahel. At these rates, much, if not all of the continent will fail to meet the Sustainable Development Goal target-to end malnutrition by 2030. Geospatial estimates of child growth failure provide a baseline for measuring progress as well as a precision public health platform to target interventions to those populations with the greatest need, in order to reduce health disparities and accelerate progress.
Subject(s)
Child Development , Growth Disorders/epidemiology , Growth , Malnutrition/epidemiology , Wasting Syndrome/epidemiology , Africa/epidemiology , Child, Preschool , Female , Goals , Growth Disorders/prevention & control , Humans , Infant , Infant, Newborn , Male , Malnutrition/prevention & control , Prevalence , Public Health/statistics & numerical data , Thinness/epidemiology , Thinness/prevention & control , Wasting Syndrome/prevention & control , World Health OrganizationABSTRACT
BACKGROUND: Cholera surveillance relies on clinical diagnosis of acute watery diarrhea. Suspected cholera case definitions have high sensitivity but low specificity, challenging our ability to characterize cholera burden and epidemiology. Our objective was to estimate the proportion of clinically suspected cholera that are true Vibrio cholerae infections and identify factors that explain variation in positivity. METHODS AND FINDINGS: We conducted a systematic review of studies that tested ≥10 suspected cholera cases for V. cholerae O1/O139 using culture, PCR, and/or a rapid diagnostic test. We searched PubMed, Embase, Scopus, and Google Scholar for studies that sampled at least one suspected case between January 1, 2000 and April 19, 2023, to reflect contemporary patterns in V. cholerae positivity. We estimated diagnostic test sensitivity and specificity using a latent class meta-analysis. We estimated V. cholerae positivity using a random-effects meta-analysis, adjusting for test performance. We included 119 studies from 30 countries. V. cholerae positivity was lower in studies with representative sampling and in studies that set minimum ages in suspected case definitions. After adjusting for test performance, on average, 52% (95% credible interval (CrI): 24%, 80%) of suspected cases represented true V. cholerae infections. After adjusting for test performance and study methodology, the odds of a suspected case having a true infection were 5.71 (odds ratio 95% CrI: 1.53, 15.43) times higher when surveillance was initiated in response to an outbreak than in non-outbreak settings. Variation across studies was high, and a limitation of our approach was that we were unable to explain all the heterogeneity with study-level attributes, including diagnostic test used, setting, and case definitions. CONCLUSIONS: In this study, we found that burden estimates based on suspected cases alone may overestimate the incidence of medically attended cholera by 2-fold. However, accounting for cases missed by traditional clinical surveillance is key to unbiased cholera burden estimates. Given the substantial variability in positivity between settings, extrapolations from suspected to confirmed cases, which is necessary to estimate cholera incidence rates without exhaustive testing, should be based on local data.
Subject(s)
Cholera , Vibrio cholerae , Humans , Cholera/diagnosis , Cholera/epidemiology , Vibrio cholerae/genetics , Disease Outbreaks , Diarrhea/epidemiology , Polymerase Chain ReactionABSTRACT
We applied a new serosurveillance tool to estimate typhoidal Salmonella burden using samples collected during 2020 from a population in Juba, South Sudan. By using dried blood spot testing, we found an enteric fever seroincidence rate of 30/100 person-years and cumulative incidence of 74% over a 4-year period.
Subject(s)
Paratyphoid Fever , Typhoid Fever , Humans , Typhoid Fever/epidemiology , Salmonella paratyphi A , Salmonella typhi , South Sudan/epidemiology , Salmonella , Paratyphoid Fever/epidemiologyABSTRACT
Relatively few coronavirus disease cases and deaths have been reported from sub-Saharan Africa, although the extent of its spread remains unclear. During August 10-September 11, 2020, we recruited 2,214 participants for a representative household-based cross-sectional serosurvey in Juba, South Sudan. We found 22.3% of participants had severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain IgG titers above prepandemic levels. After accounting for waning antibody levels, age, and sex, we estimated that 38.3% (95% credible interval 31.8%-46.5%) of the population had been infected with SARS-CoV-2. At this rate, for each PCR-confirmed SARS-CoV-2 infection reported by the Ministry of Health, 103 (95% credible interval 86-126) infections would have been unreported, meaning SARS-CoV-2 has likely spread extensively within Juba. We also found differences in background reactivity in Juba compared with Boston, Massachusetts, USA, where the immunoassay was validated. Our findings underscore the need to validate serologic tests in sub-Saharan Africa populations.
Subject(s)
COVID-19 , SARS-CoV-2 , Africa South of the Sahara , Antibodies, Viral , Boston , Cross-Sectional Studies , Humans , Immunoglobulin G , Massachusetts , Seroepidemiologic Studies , South SudanABSTRACT
BACKGROUND: Oral rehydration solution (ORS) is a simple intervention that can prevent childhood deaths from severe diarrhea and dehydration. In a previous study, we mapped the use of ORS treatment subnationally and found that ORS coverage increased over time, while the use of home-made alternatives or recommended home fluids (RHF) decreased, in many countries. These patterns were particularly striking within Senegal, Mali, and Sierra Leone. It was unclear, however, whether ORS replaced RHF in these locations or if children were left untreated, and if these patterns were associated with health policy changes. METHODS: We used a Bayesian geostatistical model and data from household surveys to map the percentage of children with diarrhea that received (1) any ORS, (2) only RHF, or (3) no oral rehydration treatment between 2000 and 2018. This approach allowed examination of whether RHF was replaced with ORS before and after interventions, policies, and external events that may have impacted healthcare access. RESULTS: We found that RHF was replaced with ORS in most Sierra Leone districts, except those most impacted by the Ebola outbreak. In addition, RHF was replaced in northern but not in southern Mali, and RHF was not replaced anywhere in Senegal. In Senegal, there was no statistical evidence that a national policy promoting ORS use was associated with increases in coverage. In Sierra Leone, ORS coverage increased following a national policy change that abolished health costs for children. CONCLUSIONS: Children in parts of Mali and Senegal have been left behind during ORS scale-up. Improved messaging on effective diarrhea treatment and/or increased ORS access such as through reducing treatment costs may be needed to prevent child deaths in these areas.
Subject(s)
Diarrhea/therapy , Fluid Therapy , Health Policy/trends , Administration, Oral , Bicarbonates/therapeutic use , Child , Child Mortality/history , Child Mortality/trends , Child, Preschool , Diarrhea/epidemiology , Female , Fluid Therapy/history , Fluid Therapy/methods , Fluid Therapy/statistics & numerical data , Fluid Therapy/trends , Glucose/therapeutic use , Health Policy/history , History, 20th Century , History, 21st Century , Humans , Infant , Male , Mali/epidemiology , Potassium Chloride/therapeutic use , Senegal/epidemiology , Severity of Illness Index , Sierra Leone/epidemiology , Sodium Chloride/therapeutic use , Spatial Analysis , Time Factors , Treatment OutcomeABSTRACT
BACKGROUND: The host, microbial, and environmental factors that contribute to variation in tuberculosis (TB) disease are incompletely understood. Accumulating evidence suggests that one driver of geographic variation in TB disease is the local ecology of mycobacterial genotypes or strains, and there is a need for a comprehensive and systematic synthesis of these data. The objectives of this study were to (1) map the global distribution of genotypes that cause TB disease and (2) examine whether any epidemiologically relevant clinical characteristics were associated with those genotypes. METHODS: We performed a systematic review of PubMed and Scopus to create a comprehensive dataset of human TB molecular epidemiology studies that used representative sampling techniques. The methods were developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We extracted and synthesized data from studies that reported prevalence of bacterial genotypes and from studies that reported clinical characteristics associated with those genotypes. RESULTS: The results of this study are twofold. First, we identified 206 studies for inclusion in the study, representing over 200,000 bacterial isolates collected over 27 years in 85 countries. We mapped the genotypes and found that, consistent with previously published maps, Euro-American lineage 4 and East Asian lineage 2 strains are widespread, and West African lineages 5 and 6 strains are geographically restricted. Second, 30 studies also reported transmission chains and 4 reported treatment failure associated with genotypes. We performed a meta-analysis and found substantial heterogeneity across studies. However, based on the data available, we found that lineage 2 strains may be associated with increased risk of transmission chains, while lineages 5 and 6 strains may be associated with reduced risk, compared with lineage 4 strains. CONCLUSIONS: This study provides the most comprehensive systematic analysis of the evidence for diversity in bacterial strains that cause TB disease. The results show both geographic and epidemiological differences between strains, which could inform our understanding of the global burden of TB. Our findings also highlight the challenges of collecting the clinical data required to inform TB diagnosis and treatment. We urge future national TB programs and research efforts to prioritize and reinforce clinical data collection in study designs and results dissemination.
Subject(s)
Genetic Variation/genetics , Global Health/standards , Molecular Epidemiology/methods , Mycobacterium tuberculosis/pathogenicity , Genotype , Humans , Research DesignABSTRACT
BACKGROUND: Brazil has high burdens of tuberculosis (TB) and HIV, as previously estimated for the 26 states and the Federal District, as well as high levels of inequality in social and health indicators. We improved the geographic detail of burden estimation by modelling deaths due to TB and HIV and TB case fatality ratios for the more than 5400 municipalities in Brazil. METHODS: This ecological study used vital registration data from the national mortality information system and TB case notifications from the national communicable disease notification system from 2001 to 2015. Mortality due to TB and HIV was modelled separately by cause and sex using a Bayesian spatially explicit mixed effects regression model. TB incidence was modelled using the same approach. Results were calibrated to the Global Burden of Disease Study 2016. Case fatality ratios were calculated for TB. RESULTS: There was substantial inequality in TB and HIV mortality rates within the nation and within states. National-level TB mortality in people without HIV infection declined by nearly 50% during 2001 to 2015, but HIV mortality declined by just over 20% for males and 10% for females. TB and HIV mortality rates for municipalities in the 90th percentile nationally were more than three times rates in the 10th percentile, with nearly 70% of the worst-performing municipalities for male TB mortality and more than 75% for female mortality in 2001 also in the worst decile in 2015. The same municipality ranking metric for HIV was observed to be between 55% and 61%. Within states, the TB mortality rate ratios by sex for municipalities in the worst decile versus the best decile varied from 1.4 to 2.9, and HIV varied from 1.4 to 4.2. The World Health Organization target case fatality rate for TB of less than 10% was achieved in 9.6% of municipalities for males versus 38.4% for females in 2001 and improved to 38.4% and 56.6% of municipalities for males versus females, respectively, by 2014. CONCLUSIONS: Mortality rates in municipalities within the same state exhibited nearly as much relative variation as within the nation as a whole. Monitoring the mortality burden at this level of geographic detail is critical for guiding precision public health responses.
Subject(s)
HIV Infections/prevention & control , Tuberculosis/prevention & control , Brazil , Female , HIV Infections/epidemiology , History, 21st Century , Humans , Male , Tuberculosis/epidemiologyABSTRACT
Type I interferons (including IFNαß) are innate cytokines that may contribute to pathogenesis during Mycobacterium tuberculosis (Mtb) infection. To induce IFNß, Mtb must gain access to the host cytosol and trigger stimulator of interferon genes (STING) signaling. A recently proposed model suggests that Mtb triggers STING signaling through bacterial DNA binding cyclic GMP-AMP synthase (cGAS) in the cytosol. The aim of this study was to test the generalizability of this model using phylogenetically distinct strains of the Mtb complex (MTBC). We infected bone marrow derived macrophages with strains from MTBC Lineages 2, 4 and 6. We found that the Lineage 6 strain induced less IFNß, and that the Lineage 2 strain induced more IFNß, than the Lineage 4 strain. The strains did not differ in their access to the host cytosol and IFNß induction by each strain required both STING and cGAS. We also found that the three strains shed similar amounts of bacterial DNA. Interestingly, we found that the Lineage 6 strain was associated with less mitochondrial stress and less mitochondrial DNA (mtDNA) in the cytosol compared with the Lineage 4 strain. Treating macrophages with a mitochondria-specific antioxidant reduced cytosolic mtDNA and inhibited IFNß induction by the Lineage 2 and 4 strains. We also found that the Lineage 2 strain did not induce more mitochondrial stress than the Lineage 4 strain, suggesting that additional pathways contribute to higher IFNß induction. These results indicate that the mechanism for IFNß by Mtb is more complex than the established model suggests. We show that mitochondrial dynamics and mtDNA contribute to IFNß induction by Mtb. Moreover, we show that the contribution of mtDNA to the IFNß response varies by MTBC strain and that additional mechanisms exist for Mtb to induce IFNß.
Subject(s)
Interferon Type I/immunology , Macrophages/immunology , Mycobacterium tuberculosis/immunology , Tuberculosis/immunology , Animals , Bone Marrow Cells , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Immunoblotting , Interferon Type I/biosynthesis , Mice , Mice, Inbred C57BL , Microscopy, Fluorescence , Mycobacterium tuberculosis/genetics , Reverse Transcriptase Polymerase Chain Reaction , Tuberculosis/geneticsABSTRACT
Type I interferons (IFNs, including IFN-αß) contribute to the pathogenesis of Mycobacterium tuberculosis strains that induce high IFN-αß levels. In the current study we examined the role of IFN-αß during infection with a Mycobacterium africanum strain that induces low IFN-ß levels. We infected wild-type and IFN-αß receptor knockout mice with M. africanum and monitored bacterial growth, lung disease, and survival over 292 days. We found reduced lung bacterial burdens and less severe histopathological findings in the absence of IFN-αß signaling. We conclude that IFN-αß is pathogenic during chronic M. africanum infection and that the pathogenic effects may be mediated through poorer control of bacterial growth.
Subject(s)
Interferon Type I/metabolism , Mycobacterium/immunology , Tuberculosis, Pulmonary/pathology , Animals , Bacterial Load , Chronic Disease , Disease Models, Animal , Histocytochemistry , Lung/microbiology , Lung/pathology , Male , Mice, Inbred C57BL , Mice, Knockout , Receptors, Interferon/deficiency , Survival Analysis , Tuberculosis, Pulmonary/microbiologyABSTRACT
Macrophages adopt an alternatively activated phenotype (AAMs) when activated by the interleukin-4receptor(R)α. AAMs can be derived either from proliferation of tissue resident macrophages or recruited inflammatory monocytes, but it is not known whether these different sources generate AAMs that are phenotypically and functionally distinct. By transcriptional profiling analysis, we show here that, although both monocyte and tissue-derived AAMs expressed high levels of Arg1, Chi3l3, and Retnla, only monocyte-derived AAMs up-regulated Raldh2 and PD-L2. Monocyte-derived AAMs were also CX3CR1-green fluorescent protein (GFP)(high) and expressed CD206, whereas tissue-derived AAMs were CX3CR1-GFP and CD206 negative. Monocyte-derived AAMs had high levels of aldehyde dehydrogenase activity and promoted the differentiation of FoxP3(+) cells from naïve CD4(+) cells via production of retinoic acid. In contrast, tissue-derived AAMs expressed high levels of uncoupling protein 1. Hence monocyte-derived AAM have properties associated with immune regulation, and the different physiological properties associated with AAM function may depend on the distinct lineage of these cells.
Subject(s)
Gene Expression Profiling , Macrophage Activation , Macrophages/immunology , Monocytes/immunology , Animals , CD4 Antigens/analysis , Cell Proliferation , Cells, Cultured , Forkhead Transcription Factors/analysis , Gene Expression , Ion Channels/analysis , Ion Channels/genetics , Macrophages/cytology , Macrophages/metabolism , Mice , Mice, Inbred C57BL , Mitochondrial Proteins/analysis , Mitochondrial Proteins/genetics , Monocytes/cytology , Monocytes/metabolism , Uncoupling Protein 1ABSTRACT
Idiopathic chronic diarrhea (ICD) is a leading cause of morbidity amongst rhesus monkeys kept in captivity. Here, we show that exposure of affected animals to the whipworm Trichuris trichiura led to clinical improvement in fecal consistency, accompanied by weight gain, in four out of the five treated monkeys. By flow cytometry analysis of pinch biopsies collected during colonoscopies before and after treatment, we found an induction of a mucosal T(H)2 response following helminth treatment that was associated with a decrease in activated CD4(+) Ki67+ cells. In parallel, expression profiling with oligonucleotide microarrays and real-time PCR analysis revealed reductions in T(H)1-type inflammatory gene expression and increased expression of genes associated with IgE signaling, mast cell activation, eosinophil recruitment, alternative activation of macrophages, and worm expulsion. By quantifying bacterial 16S rRNA in pinch biopsies using real-time PCR analysis, we found reduced bacterial attachment to the intestinal mucosa post-treatment. Finally, deep sequencing of bacterial 16S rRNA revealed changes to the composition of microbial communities attached to the intestinal mucosa following helminth treatment. Thus, the genus Streptophyta of the phylum Cyanobacteria was vastly increased in abundance in three out of five ICD monkeys relative to healthy controls, but was reduced to control levels post-treatment; by contrast, the phylum Tenericutes was expanded post-treatment. These findings suggest that helminth treatment in primates can ameliorate colitis by restoring mucosal barrier functions and reducing overall bacterial attachment, and also by altering the communities of attached bacteria. These results also define ICD in monkeys as a tractable preclinical model for ulcerative colitis in which these effects can be further investigated.
Subject(s)
Colon/immunology , Diarrhea/immunology , Diarrhea/therapy , Diarrhea/veterinary , Intestinal Mucosa/immunology , Monkey Diseases/immunology , Monkey Diseases/therapy , Therapy with Helminths , Trichuris , Animals , Chronic Disease , Colon/microbiology , Cyanobacteria/immunology , Diarrhea/microbiology , Female , Inflammation/immunology , Inflammation/microbiology , Inflammation/therapy , Intestinal Mucosa/microbiology , Macaca mulatta , Male , Monkey Diseases/microbiology , Th1 Cells/immunology , Th2 Cells/immunologyABSTRACT
Systematic testing for Vibrio cholerae O1 is rare, which means that the world's limited supply of oral cholera vaccines (OCVs) may not be delivered to areas with the highest true cholera burden. Here we used a phenomenological model with subnational geographic targeting and fine-scale vaccine effects to model how expanding V. cholerae testing affected impact and cost-effectiveness for preventive vaccination campaigns across different bacteriological confirmation and vaccine targeting assumptions in 35 African countries. Systematic testing followed by OCV targeting based on confirmed cholera yielded higher efficiency and cost-effectiveness and slightly fewer averted cases than status quo scenarios targeting suspected cholera. Targeting vaccine to populations with an annual incidence rate greater than 10 per 10,000, the testing scenario averted 10.8 (95% prediction interval (PI) 9.4-12.6) cases per 1,000 fully vaccinated persons while the status quo scenario averted 6.9 (95% PI 6.0-7.8) cases per 1,000 fully vaccinated persons. In the testing scenario, testing costs increased by US$31 (95% PI 25-39) while vaccination costs reduced by US$248 (95% PI 176-326) per averted case compared to the status quo. Introduction of systematic testing into cholera surveillance could improve efficiency and reach of global OCV supply for preventive vaccination.
Subject(s)
Cholera Vaccines , Cholera , Humans , Cholera/epidemiology , Cholera/prevention & control , Administration, Oral , Immunization Programs , VaccinationABSTRACT
Our understanding of cholera transmission and burden largely relies on clinic-based surveillance, which can obscure trends, bias burden estimates and limit the impact of targeted cholera-prevention measures. Serological surveillance provides a complementary approach to monitoring infections, although the link between serologically derived infections and medically attended disease incidence-shaped by immunological, behavioral and clinical factors-remains poorly understood. We unravel this cascade in a cholera-endemic Bangladeshi community by integrating clinic-based surveillance, healthcare-seeking and longitudinal serological data through statistical modeling. Combining the serological trajectories with a reconstructed incidence timeline of symptomatic cholera, we estimated an annual Vibrio cholerae O1 infection incidence rate of 535 per 1,000 population (95% credible interval 514-556), with incidence increasing by age group. Clinic-based surveillance alone underestimated the number of infections and reported cases were not consistently correlated with infection timing. Of the infections, 4 in 3,280 resulted in symptoms, only 1 of which was reported through the surveillance system. These results impart insights into cholera transmission dynamics and burden in the epicenter of the seventh cholera pandemic, where >50% of our study population had an annual V. cholerae O1 infection, and emphasize the potential for a biased view of disease burden and infection risk when depending solely on clinical surveillance data.
Subject(s)
Cholera , Vibrio cholerae , Humans , Cholera/epidemiology , IncidenceABSTRACT
BACKGROUND: Vibriocidal antibodies are currently the best characterised correlate of protection against cholera and are used to gauge immunogenicity in vaccine trials. Although other circulating antibody responses have been associated with a decreased risk of infection, the correlates of protection against cholera have not been comprehensively compared. We aimed to analyse antibody-mediated correlates of protection from both V cholerae infection and cholera-related diarrhoea. METHODS: We conducted a systems serology study that analysed 58 serum antibody biomarkers as correlates of protection against V cholerae O1 infection or diarrhoea. We used serum samples from two cohorts: household contacts of people with confirmed cholera in Dhaka, Bangladesh, and cholera-naive volunteers who were recruited at three centres in the USA, vaccinated with a single dose of CVD 103-HgR live oral cholera vaccine, and then challenged with V cholerae O1 El Tor Inaba strain N16961. We measured antigen-specific immunoglobulin responses against antigens using a customised Luminex assay and used conditional random forest models to examine which baseline biomarkers were most important for classifying individuals who went on to develop infection versus those who remained uninfected or asymptomatic. V cholerae infection was defined as having a positive stool culture result on days 2-7 or day 30 after enrolment of the household's index cholera case and, in the vaccine challenge cohort, was the development of symptomatic diarrhoea (defined as two or more loose stools of ≥200 mL each, or a single loose stool of ≥300 mL over a 48-h period). FINDINGS: In the household contact cohort (261 participants from 180 households), 20 (34%) of the 58 studied biomarkers were associated with protection against V cholerae infection. We identified serum antibody-dependent complement deposition targeting the O1 antigen as the most predictive correlate of protection from infection in the household contacts, whereas vibriocidal antibody titres ranked lower. A five-biomarker model predicted protection from V cholerae infection with a cross-validated area under the curve (cvAUC) of 79% (95% CI 73-85). This model also predicted protection against diarrhoea in unvaccinated volunteers challenged with V cholerae O1 after vaccination (n=67; area under the curve [AUC] 77%, 95% CI 64-90). Although a different five-biomarker model best predicted protection from the development of cholera diarrhoea in the challenged vaccinees (cvAUC 78%, 95% CI 66-91), this model did poorly at predicting protection against infection in the household contacts (AUC 60%, 52-67). INTERPRETATION: Several biomarkers predict protection better than vibriocidal titres. A model based on protection against infection among household contacts was predictive of protection against both infection and diarrhoeal illness in challenged vaccinees, suggesting that models based on observed conditions in a cholera-endemic population might be more likely to identify broadly applicable correlates of protection than models trained on single experimental settings. FUNDING: National Institute of Allergy and Infectious Diseases and National Institute of Child Health and Human Development, National Institutes of Health.
Subject(s)
Cholera , Vibrio cholerae , Child , Humans , Cholera/epidemiology , Cholera/prevention & control , Antibodies, Bacterial , Bangladesh/epidemiology , Diarrhea/epidemiologyABSTRACT
Because of the importance of schools to childhood development, the relationship between in-person schooling and COVID-19 risk has been one of the most important questions of this pandemic. Previous work in the United States during winter 2020-2021 showed that in-person schooling carried some risk for household members and that mitigation measures reduced this risk. Schooling and the COVID-19 landscape changed radically over spring semester 2021. Here, we use data from a massive online survey to characterize changes in in-person schooling behavior and associated risks over that period. We find increases in in-person schooling and reductions in mitigations over time. In-person schooling is associated with increased reporting of COVID-19 outcomes even among vaccinated individuals (although the absolute risk among the vaccinated is greatly reduced). Vaccinated teachers working outside the home were less likely to report COVID-19-related outcomes than unvaccinated teachers working exclusively from home. Adequate mitigation measures appear to eliminate the excess risk associated with in-person schooling.
ABSTRACT
The use of biomarkers to measure immune responses in serum is crucial for understanding population-level exposure and susceptibility to human pathogens. Advances in sample collection, multiplex testing, and computational modeling are transforming serosurveillance into a powerful tool for public health program design and response to infectious threats. In July 2018, 70 scientists from 16 countries met to perform a landscape analysis of approaches that support an integrated serosurveillance platform, including the consideration of issues for successful implementation. Here, we summarize the group's insights and proposed roadmap for implementation, including objectives, technical requirements, ethical issues, logistical considerations, and monitoring and evaluation.
Subject(s)
Communicable Diseases , Public Health , Biomarkers , HumansABSTRACT
BACKGROUND: Relatively few COVID-19 cases and deaths have been reported through much of sub-Saharan Africa, including South Sudan, although the extent of SARS-CoV-2 spread remains unclear due to weak surveillance systems and few population-representative serosurveys. METHODS: We conducted a representative household-based cross-sectional serosurvey in Juba, South Sudan. We quantified IgG antibody responses to SARS-CoV-2 spike protein receptor-binding domain and estimated seroprevalence using a Bayesian regression model accounting for test performance. RESULTS: We recruited 2,214 participants from August 10 to September 11, 2020 and 22.3% had anti-SARS-CoV-2 IgG titers above levels in pre-pandemic samples. After accounting for waning antibody levels, age, and sex, we estimated that 38.5% (32.1 - 46.8) of the population had been infected with SARS-CoV-2. For each RT-PCR confirmed COVID-19 case, 104 (87-126) infections were unreported. Background antibody reactivity was higher in pre-pandemic samples from Juba compared to Boston, where the serological test was validated. The estimated proportion of the population infected ranged from 30.1% to 60.6% depending on assumptions about test performance and prevalence of clinically severe infections. CONCLUSIONS: SARS-CoV-2 has spread extensively within Juba. Validation of serological tests in sub-Saharan African populations is critical to improve our ability to use serosurveillance to understand and mitigate transmission.