Ongoing transmission of trachoma in low prevalence districts in Mozambique: results from four cross-sectional enhanced impact surveys, 2022.

Mozambique is making progress towards elimination of trachoma as a public health problem, but in some districts trachomatous inflammation-follicular (TF) prevalence remains above the 5% elimination threshold despite years of various interventions, including antibiotic mass drug administration. To characterize transmission in four districts, we incorporated testing of ocular infection and serology into routine trachoma impact surveys (TIS) in August 2022. We examined residents aged ≥ 1 year for trachoma and collected information on household water, sanitation, and hygiene. Among children aged 1-9 years, we tested conjunctival swabs for Chlamydia trachomatis nucleic acid and dried blood spots for C. trachomatis antibodies. We modeled age-dependent seroprevalence to estimate seroconversion rate (SCR). We examined 4841 children aged 1-9 years. TF prevalence ranged between 1.1 and 6.0% with three districts below the 5% threshold. PCR-confirmed infection prevalence ranged between 1.1 and 4.8%, and Pgp3 seroprevalence ranged between 8.8 and 24.3%. Pgp3 SCR was 1.9 per 100 children per year in the district with the lowest TF prevalence. Two other districts with TF < 5% had SCR of 5.0 and 4.7. The district with TF ≥ 5% had a SCR of 6.0. This enhanced TIS furthered understanding of transmission in these districts and provides information on additional indicators for monitoring trachoma programs.

Challenges and Approaches to Establishing Multi-Pathogen Serosurveillance: Findings from the 2023 Serosurveillance Summit.

Multiplex-based serological surveillance is a valuable but underutilized tool to understand gaps in population-level exposure, susceptibility, and immunity to infectious diseases. Assays for which blood samples can be tested for antibodies against several pathogens simultaneously, such as multiplex bead immunoassays, can more efficiently integrate public health surveillance in low- and middle-income countries. On March 7-8, 2023 a group of experts representing research institutions, multilateral organizations, private industry, and country partners met to discuss experiences, identify challenges and solutions, and create a community of practice for integrated, multi-pathogen serosurveillance using multiplex bead assay technologies. Participants were divided into six working groups: 1) supply chain; 2) laboratory assays; 3) seroepidemiology; 4) data analytics; 5) sustainable implementation; and 6) use case scenarios. These working groups discussed experiences, challenges, solutions, and research needs to facilitate integrated, multi-pathogen serosurveillance for public health. Several solutions were proposed to address challenges that cut across working groups.

Integrated Serosurveillance for Onchocerciasis, Lymphatic Filariasis, and Schistosomiasis in North Darfur, Sudan.

Sudan is endemic for multiple neglected tropical diseases, including trachoma, onchocerciasis (OV), lymphatic filariasis (LF), and schistosomiasis (SCH). In 2019, dried blood spot samples were collected for a baseline trachoma serosurvey in three localities (El Seraif, Kotom, and Saraf Omrah) in North Darfur State. None were classified previously as OV- or LF-endemic, although low levels of SCH had been identified in all three. Approximately 30 households from 25 communities in each locality were selected by multistage cluster random sampling. Collections of DBSs were analyzed by multiplex bead assay for antibodies to multiple pathogens. This paper presents data on OV (Ov16), LF (Wb123, Bm14, Bm33), and SCH (soluble egg antigen [SEA], Sm25) antibodies among 8,322 individuals from 2,119 households. The survey-adjusted seroprevalence estimates for Ov16 were <0.3% in all localities. Lymphatic filariasis-antigen seroprevalences were discordant. Seroprevalence estimates ranged from 4.6-6.0% (Wb123), 0.99-1.4% (Bm14), and 29.2-33.3% (Bm33). Schistosomiasis seroprevalence estimates among school-aged children ranged from 2.7-8.0% (SEA) and 10.9-15.6% (Sm25). Ov16 seropositivity was low and supported the localities' classification as nonendemic. The results suggested LF exposure, but discordance between antigens, challenges defining seropositivity thresholds, and the absence of programmatic guidance based on antibody serology alone for Wuchereria bancrofti indicate a need for remapping surveys to confirm transmission. Schistosomiasis antibody levels were high enough to warrant further mapping to guide treatment decisions. The lack of gold standards limited interpretation of results, particularly for LF, but in resource-challenged areas, integrated serological surveillance offers the possibility of efficient monitoring of exposure to multiple diseases.

Climate change, malaria and neglected tropical diseases: a scoping review.

To explore the effects of climate change on malaria and 20 neglected tropical diseases (NTDs), and potential effect amelioration through mitigation and adaptation, we searched for papers published from January 2010 to October 2023. We descriptively synthesised extracted data. We analysed numbers of papers meeting our inclusion criteria by country and national disease burden, healthcare access and quality index (HAQI), as well as by climate vulnerability score. From 42 693 retrieved records, 1543 full-text papers were assessed. Of 511 papers meeting the inclusion criteria, 185 studied malaria, 181 dengue and chikungunya and 53 leishmaniasis; other NTDs were relatively understudied. Mitigation was considered in 174 papers (34%) and adaption strategies in 24 (5%). Amplitude and direction of effects of climate change on malaria and NTDs are likely to vary by disease and location, be non-linear and evolve over time. Available analyses do not allow confident prediction of the overall global impact of climate change on these diseases. For dengue and chikungunya and the group of non-vector-borne NTDs, the literature privileged consideration of current low-burden countries with a high HAQI. No leishmaniasis papers considered outcomes in East Africa. Comprehensive, collaborative and standardised modelling efforts are needed to better understand how climate change will directly and indirectly affect malaria and NTDs.

Serological Responses to Trachoma Antigens prior to the Start of Mass Drug Administration: Results from Population-Based Baseline Surveys, North Darfur, Sudan.

After years of programmatic inaccessibility, in 2019-2020 the Sudan Federal Ministry of Health Trachoma Control Program conducted population-based trachoma surveys in three localities (districts) in North Darfur state, Sudan. These baseline surveys were to determine the prevalence of trachomatous inflammation-follicular (TF) among children aged 1-9 years and to further use serological markers to understand the historical trachoma burden within this mass drug administration (MDA)-naive area. Trained and certified graders collected trachoma clinical data, and trained nurses collected dried blood spot (DBS) samples. The DBSs were assayed on a multiplex bead array for antibody responses to the Chlamydia trachomatis antigens Pgp3 and CT694. Across the three localities, 3,613 individuals aged 1-9 years and 3,542 individuals aged ≥15 years were examined for clinical signs, and 8,322 DBSs were collected. The prevalence of TF among children aged 1-9 years was endemic (≥5%) in two localities (El Seraif, 15.6%, and Saraf Omrah, 11.0%) and below the TF elimination threshold (<5%) in the third (Kotom, 1.4%). The Pgp3 seroprevalence among children aged 1-9 years was 34.1% in El Seraif, 35.0% in Saraf Omrah, and 11.0% in Kotom. Locality prevalence results were similar for Pgp3 and CT694. Seroprevalence increased with age in all three localities. Serological data collected within these surveys demonstrate that all three localities have had a long history of exposure to Chlamydia trachomatis and that two of the three localities require MDA to reach elimination as a public health problem threshold.

Wait and watch: A trachoma surveillance strategy from Amhara region, Ethiopia.

BACKGROUND: Trachoma recrudescence after elimination as a public health problem has been reached is a concern for control programs globally. Programs typically conduct district-level trachoma surveillance surveys (TSS) ≥ 2 years after the elimination threshold is achieved to determine whether the prevalence of trachomatous inflammation-follicular (TF) among children ages 1 to 9 years remains <5%. Many TSS are resulting in a TF prevalence ≥5%. Once a district returns to TF ≥5%, a program typically restarts costly mass drug administration (MDA) campaigns and surveys at least twice, for impact and another TSS. In Amhara, Ethiopia, most TSS which result in a TF ≥5% have a prevalence close to 5%, making it difficult to determine whether the result is due to true recrudescence or to statistical variability. This study's aim was to monitor recrudescence within Amhara by waiting to restart MDA within 2 districts with a TF prevalence ≥5% at TSS, Metema = 5.2% and Woreta Town = 5.1%. The districts were resurveyed 1 year later using traditional and alternative indicators, such as measures of infection and serology, a "wait and watch" approach. METHODS/PRINCIPAL FINDINGS: These post-surveillance surveys, conducted in 2021, were multi-stage cluster surveys whereby certified graders assessed trachoma signs. Children ages 1 to 9 years provided a dried blood spot and children ages 1 to 5 years provided a conjunctival swab. TF prevalence in Metema and Woreta Town were 3.6% (95% Confidence Interval [CI]:1.4-6.4) and 2.5% (95% CI:0.8-4.5) respectively. Infection prevalence was 1.2% in Woreta Town and 0% in Metema. Seroconversion rates to Pgp3 in Metema and Woreta Town were 0.4 (95% CI:0.2-0.7) seroconversions per 100 child-years and 0.9 (95% CI:0.6-1.5) respectively. CONCLUSIONS/SIGNIFICANCE: Both study districts had a TF prevalence <5% with low levels of Chlamydia trachomatis infection and transmission, and thus MDA interventions are no longer warranted. The wait and watch approach represents a surveillance strategy which could lead to fewer MDA campaigns and surveys and thus cost savings with reduced antibiotic usage.

Schistosomiasis Seroprevalence among Children Aged 0-14 Years in Nigeria, 2018.

The first nationally representative, population-based study of schistosomiasis seroprevalence in Nigeria was conducted using blood samples and risk-factor data collected during the 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS). Schistosomiasis seroprevalence was estimated by analyzing samples for reactivity to schistosome soluble egg antigen (SEA) in a multiplex bead assay; NAIIS survey data were assessed to identify potential risk factors for seropositivity. The SEA antibody data were available for 31,459 children aged 0 to 14 years. Overall seroprevalence was 17.2% (95% CI: 16.3-18.1%). Seropositive children were identified in every age group, including children < 5 years, and seroprevalence increased with increasing age (P < 0.0001). Several factors were associated with increased odds of seropositivity, including being a boy (odds ratio [OR] = 1.34, 95% CI: 1.24-1.45), living in a rural area (OR = 2.2, 95% CI: 1.9-2.5), and animal ownership (OR = 1.67, 95% CI: 1.52-1.85). Access to improved sanitation and drinking water sources were associated with decreased odds of seropositivity (OR = 0.52, 95% CI: 0.47-0.58 and OR = 0.53, 95% CI: 0.47-0.60, respectively) regardless of whether the child lived in a rural (sanitation: adjusted odds ratio [aOR] = 0.7, 95% CI: 0.6-0.8; drinking water: aOR = 0.7, 95% CI: 0.6-0.8) or urban area (sanitation: aOR = 0.6, 95% CI: 0.5-0.7; drinking water: aOR = 0.5, 95% CI: 0.4-0.6), highlighting the importance of these factors for schistosomiasis prevention and control. These results identified additional risk populations (children < 5 years) and a new risk factor (animal ownership) and could be used to monitor the impact of control programs.

Seroreversion to Chlamydia trachomatis Pgp3 Antigen Among Children in a Hyperendemic Region of Amhara, Ethiopia.

Monitoring trachoma transmission with antibody data requires characterization of decay in IgG to Chlamydia trachomatis antigens. In a 3-year longitudinal cohort in a high-transmission setting, we estimated a median IgG half-life of 3 years and a seroreversion rate of 2.5 per 100 person-years (95% confidence interval, 1.6-3.5). Clinical Trials Registration NCT02754583.

High prevalence of trachomatous inflammation-follicular with no trachomatous trichiasis: can alternative indicators explain the epidemiology of trachoma in Côte d'Ivoire?

Baseline trachoma surveys in Côte d'Ivoire (2019) identified seven evaluation units (EUs) with a trachomatous inflammation-follicular (TF) prevalence ≥10%, but a trachomatous trichiasis (TT) prevalence in individuals ≥15 y of age below the elimination threshold (0.2%). Two of these EUs, Bondoukou 1 and Bangolo 2, were selected for a follow-up survey to understand the epidemiology of trachoma using additional indicators of Chlamydia trachomatis infection (DNA from conjunctival swabs) and exposure (anti-Pgp3 and Ct694 antibodies from dried blood spots [DBSs]). A two-stage cluster sampling methodology was used to select villages and households. All individuals 1-9 y of age from each selected household were recruited, graded for trachoma and had a conjunctival swab and DBS collected. Conjunctival swabs and DBSs were tested using Cepheid GeneXpert and a multiplex bead assay, respectively. The age-adjusted TF and infection prevalence in 1- to 9-year-olds was <1% and <0.3% in both EUs. Age-adjusted seroprevalence was 5.3% (95% confidence interval [CI] 1.5 to 15.6) in Bondoukou 1 and 8.2% (95% CI 4.3 to 13.7) in Bangolo 2. The seroconversion rate for Pgp3 was low, at 1.23 seroconversions/100 children/year (95% CI 0.78 to 1.75) in Bondoukou 1 and 1.91 (95% CI 1.58 to 2.24) in Bangolo 2. Similar results were seen for CT694. These infection, antibody and clinical data provide strong evidence that trachoma is not a public health problem in either EU.

Changes in trachoma indicators in Kiribati with two rounds of azithromycin mass drug administration, measured in serial population-based surveys.

Baseline mapping in the two major population centers of Kiribati showed that trachoma was a public health problem in need of programmatic interventions. After conducting two annual rounds of antibiotic mass drug administration (MDA), Kiribati undertook trachoma impact surveys in 2019, using standardized two-stage cluster surveys in the evaluation units of Kiritimati Island and Tarawa. In Kiritimati, 516 households were visited and in Tarawa, 772 households were visited. Nearly all households had a drinking water source and access to an improved latrine. The prevalence of trachomatous trichiasis remained above the elimination threshold (0.2% in ≥15-year-olds) and was virtually unchanged from baseline. The prevalence of trachomatous inflammation-follicular (TF) in 1-9-year-olds decreased by approximately 40% from baseline in both evaluation units but remained above the 5% TF prevalence threshold for stopping MDA. TF prevalence at impact survey was 11.5% in Kiritimati and 17.9% in Tarawa. Infection prevalence in 1-9-year-olds by PCR was 0.96% in Kiritimati and 3.3% in Tarawa. Using a multiplex bead assay to measure antibodies to the C. trachomatis antigen Pgp3, seroprevalence in 1-9-year-olds was 30.2% in Kiritimati and 31.4% in Tarawa. The seroconversion rate, in seroconversion events/100 children/year, was 9.0 in Kiritimati and 9.2 in Tarawa. Seroprevalence and seroconversion rates were both assessed by four different assays, with strong agreement between tests. These results show that, despite decreases in indicators associated with infection at impact survey, trachoma remains a public health problem in Kiribati, and provide additional information about changes in serological indicators after MDA.

Monitoring transmission intensity of trachoma with serology.

Trachoma, caused by ocular Chlamydia trachomatis infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor C. trachomatis transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1-9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination. Seroprevalence (range: 0-54%) and seroconversion rates (range: 0-15 per 100 person-years) correlate with PCR prevalence (r: 0.87, 95% CI: 0.57, 0.97). A seroprevalence threshold of 13.5% (seroconversion rate 2.75 per 100 person-years) identifies clusters with any PCR-identified infection at high sensitivity ( >90%) and moderate specificity (69-75%). Antibody responses in young children provide a robust, generalizable approach to monitor population progress toward and beyond trachoma elimination.

Lessons learned from the implementation of integrated serosurveillance of communicable diseases in the Americas.

Objective: Systematize the experience and identify challenges and lessons learned in the implementation of an initiative for integrated serosurveillance of communicable diseases using a multiplex bead assay in countries of the Americas. Methods: Documents produced in the initiative were compiled and reviewed. These included concept notes, internal working papers, regional meetings reports, and survey protocols from the three participating countries (Mexico, Paraguay, and Brazil) and two additional countries (Guyana and Guatemala) where serology for several communicable diseases was included in neglected tropical diseases surveys. Information was extracted and summarized to describe the experience and the most relevant challenges and lessons learned. Results: Implementing integrated serosurveys requires interprogrammatic and interdisciplinary work teams for the design of survey protocols to respond to key programmatic questions aligned to the needs of the countries. Valid laboratory results are critical and rely on the standardized installment and roll-out of laboratory techniques. Field teams require adequate training and supervision to properly implement survey procedures. The analysis and interpretation of serosurveys results should be antigen-specific, contextualizing the responses for each disease, and triangulated with programmatic and epidemiological data for making decisions tailored to specific population socioeconomic and ecologic contexts. Conclusions: Integrated serosurveillance as a complementary tool for functional epidemiological surveillance systems is feasible to use and key components should be considered: political engagement, technical engagement, and integrated planning. Aspects such as designing the protocol, selecting target populations and diseases, laboratory capacities, anticipating the capacities to analyze and interpret complex data, and how to use it are key.

Seroreversion to Chlamydia trachomatis Pgp3 antigen among children in a hyperendemic region of Amhara, Ethiopia.

Monitoring trachoma transmission with antibody data requires characterization of decay in IgG to Chlamydia trachomatis antigens. In a three-year longitudinal cohort in a high transmission setting, we estimated a median IgG half-life of 3 years and a seroreversion rate of 2.5 (95% CI: 1.6, 3.5) per 100 person-years.

Monitoring transmission intensity of trachoma with serology.

Trachoma, caused by ocular Chlamydia trachomatis infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor C. trachomatis transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1- 9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination. Seroprevalence (range: 0-54%) and seroconversion rates (range: 0-15 per 100 person-years) correlate with PCR prevalence (r: 0.87, 95% CI: 0.57, 0.97). A seroprevalence threshold of 13.5% (seroconversion rate 2.75 per 100 person-years) identifies clusters with any PCR-identified infection at high sensitivity (>90%) and moderate specificity (69-75%). Antibody responses in young children provide a robust, generalizable approach to monitor population progress toward and beyond trachoma elimination.

Comparison of one single-antigen assay and three multi-antigen SARS-CoV-2 IgG assays in Nigeria.

Objectives: Determining an accurate estimate of SARS-CoV-2 seroprevalence has been challenging in African countries where malaria and other pathogens are endemic. We compared the performance of one single-antigen assay and three multi-antigen SARS-CoV-2 IgG assays in a Nigerian population endemic for malaria. Methods: De-identified plasma specimens from SARS-CoV-2 RT-PCR positive, dried blood spot (DBS) SARS-CoV-2 RT-PCR positive, and pre-pandemic negatives were used to evaluate the performance of the four SARS-CoV-2 assays (Tetracore, SARS2MBA, RightSign, xMAP). Results: Results showed higher sensitivity with the multi-antigen (81% (Tetracore), 96% (SARS2MBA), 85% (xMAP)) versus the single-antigen (RightSign (64%)) SARS-CoV-2 assay. The overall specificities were 98% (Tetracore), 100% (SARS2MBA and RightSign), and 99% (xMAP). When stratified based on <15 days to ≥15 days post-RT-PCR confirmation, the sensitivities increased from 75% to 88.2% for Tetracore; from 93% to 100% for the SARS2MBA; from 58% to 73% for RightSign; and from 83% to 88% for xMAP. With DBS, there was no positive increase after 15-28 days for the three assays (Tetracore, SARS2MBA, and xMAP). Conclusion: Multi-antigen assays performed well in Nigeria, even with samples with known malaria reactivity, and might provide more accurate measures of COVID-19 seroprevalence and vaccine efficacy.

Lessons learned from the implementation of integrated serosurveillance of communicable diseases in the Americas / Enseñanzas obtenidas en la aplicación de la serovigilancia integrada de las enfermedades transmisibles en la Región de las Américas / Lições aprendidas com a implementação da vigilância sorológica integrada de doenças transmissíveis nas Américas

ABSTRACT Objective. Systematize the experience and identify challenges and lessons learned in the implementation of an initiative for integrated serosurveillance of communicable diseases using a multiplex bead assay in countries of the Americas. Methods. Documents produced in the initiative were compiled and reviewed. These included concept notes, internal working papers, regional meetings reports, and survey protocols from the three participating countries (Mexico, Paraguay, and Brazil) and two additional countries (Guyana and Guatemala) where serology for several communicable diseases was included in neglected tropical diseases surveys. Information was extracted and summarized to describe the experience and the most relevant challenges and lessons learned. Results. Implementing integrated serosurveys requires interprogrammatic and interdisciplinary work teams for the design of survey protocols to respond to key programmatic questions aligned to the needs of the countries. Valid laboratory results are critical and rely on the standardized installment and roll-out of laboratory techniques. Field teams require adequate training and supervision to properly implement survey procedures. The analysis and interpretation of serosurveys results should be antigen-specific, contextualizing the responses for each disease, and triangulated with programmatic and epidemiological data for making decisions tailored to specific population socioeconomic and ecologic contexts. Conclusions. Integrated serosurveillance as a complementary tool for functional epidemiological surveillance systems is feasible to use and key components should be considered: political engagement, technical engagement, and integrated planning. Aspects such as designing the protocol, selecting target populations and diseases, laboratory capacities, anticipating the capacities to analyze and interpret complex data, and how to use it are key.

Resumen Objetivo. Sistematizar la experiencia y determinar los desafíos y las enseñanzas obtenidas durante la aplicación de una iniciativa de serovigilancia integrada de enfermedades transmisibles mediante un ensayo de perlas múltiples en países de la Región de las Américas. Métodos. Se recopilaron y revisaron los documentos generados en el marco de la iniciativa. Estos incluían notas conceptuales, documentos de trabajo internos, informes de reuniones regionales y protocolos de encuesta de los tres países participantes (Brasil, México y Paraguay) y otros dos países (Guatemala y Guyana) donde en las encuestas sobre enfermedades tropicales desatendidas también se incluía la serología para varias enfermedades transmisibles. Se recabó y resumió la información para describir tanto la experiencia como los desafíos y las enseñanzas de mayor relevancia. Resultados. La realización de encuestas serológicas integradas requiere equipos de trabajo interprogramáticos e interdisciplinarios para la elaboración de protocolos de encuesta que permitan responder a cuestiones programáticas fundamentales y ajustadas a las necesidades de los países. Es imprescindible contar con resultados de laboratorio válidos, para lo que es preciso que sus técnicas e instalaciones estén estandarizadas. Para que los equipos de campo puedan ejecutar correctamente los procedimientos de la encuesta, deben contar con una formación y supervisión adecuadas. El análisis y la interpretación de los resultados de las encuestas serológicas deben ser específicos para cada antígeno, situar las respuestas en el contexto de cada enfermedad y triangularse con los datos programáticos y epidemiológicos para tomar decisiones adaptadas a los contextos socioeconómicos y ecológicos específicos de la población. Conclusiones. Es uso de la vigilancia serológica integrada como una herramienta complementaria en los sistemas funcionales de vigilancia epidemiológica es algo posible; para esto deben tenerse en cuenta ciertos elementos fundamentales: el compromiso político, el compromiso técnico y la planificación integrada. A tal efecto, son fundamentales ciertos elementos como el diseño del protocolo, la selección de los grupos poblacionales y las enfermedades objetivo, la capacidad de los laboratorios, y la previsión de las capacidades de análisis e interpretación de datos complejos y la forma de utilizarlos.

RESUMO Objetivo. Sistematizar a experiência e identificar desafios e lições aprendidas na implementação de uma iniciativa de vigilância sorológica integrada de doenças transmissíveis, usando ensaio de micro-esferas multiplex em países das Américas. Métodos. Os documentos produzidos na iniciativa foram compilados e examinados, e incluíram notas conceituais, documentos internos de trabalho, relatórios de reuniões regionais e protocolos de pesquisa dos três países participantes (México, Paraguai e Brasil) e de dois países adicionais (Guiana e Guatemala), onde a vigilância sorológica de várias doenças transmissíveis foi incluída em pesquisas sobre doenças tropicais negligenciadas. As informações foram extraídas e resumidas para descrever a experiência e os desafios e as lições aprendidas mais relevantes. Resultados. A implementação de inquéritos sorológicos integrados requer equipes de trabalho interprogramáticas e interdisciplinares para o delineamento de protocolos que respondam a questões programáticas chave, alinhadas com as necessidades dos países. Resultados laboratoriais válidos são essenciais, e dependem da instalação e implantação padronizadas de técnicas laboratoriais. As equipes de campo precisam de treinamento e supervisão apropriados para implementar adequadamente os procedimentos de pesquisa. A análise e a interpretação dos resultados dos inquéritos sorológicos devem ser antígeno-específicas, contextualizando as respostas para cada doença, e trianguladas com dados programáticos e epidemiológicos para a tomada de decisões adaptadas aos contextos socioeconômicos e ecológicos específicos de cada população. Conclusões. A vigilância sorológica integrada como ferramenta complementar para sistemas de vigilância epidemiológica funcionais é viável. Os componentes-chave a seguir devem ser considerados: engajamento político, engajamento técnico e planejamento integrado. Aspectos como o delineamento do protocolo, a seleção de populações-alvo e doenças-alvo, a capacidade laboratorial, a previsão das capacidades para análise e interpretação de dados complexos e como usá-los são fundamentais.

Diagnostics to support the eradication of yaws-Development of two target product profiles.

BACKGROUND: Yaws is targeted for eradication by 2030, using a strategy based on mass drug administration (MDA) with azithromycin. New diagnostics are needed to aid eradication. Serology is currently the mainstay for yaws diagnosis; however, inaccuracies associated with current serological tests makes it difficult to fully assess the need for and impact of eradication campaigns using these tools. Under the recommendation of the WHO Diagnostic Technical Advisory Group (DTAG) for Neglected Tropical Diseases(NTDs), a working group was assembled and tasked with agreeing on priority use cases for developing target product profiles (TPPs) for new diagnostics tools. METHODOLOGY AND PRINCIPAL FINDINGS: The working group convened three times and established two use cases: identifying a single case of yaws and detecting azithromycin resistance. One subgroup assessed the current diagnostic landscape for yaws and a second subgroup determined the test requirements for both use cases. Draft TPPs were sent out for input from stakeholders and experts. Both TPPs considered the following parameters: product use, design, performance, configuration, cost, access and equity. To identify a single case of yaws, the test should be able to detect an analyte which confirms an active infection with at least 95% sensitivity and 99.9% specificity. The high specificity was deemed important to avoid a high false positive rate which could result in unnecessary continuation or initiation of MDA campaigns. If used in settings where the number of suspected cases is low, further testing could be considered to compensate for imperfect sensitivity and to improve specificity. The test to detect azithromycin resistance should be able to detect known genetic resistance mutations with a minimum sensitivity and specificity of 95%, with the caveat that all patients with suspected treatment failure should be treated as having resistant yaws and offered alternative treatment. CONCLUSIONS: The TPPs developed will provide test developers with guidance to ensure that novel diagnostic tests meet identified public health needs.

Effect of Biannual Mass Azithromycin Distributions to Preschool-Aged Children on Trachoma Prevalence in Niger: A Cluster Randomized Clinical Trial.

Importance: Because transmission of ocular strains of Chlamydia trachomatis is greatest among preschool-aged children, limiting azithromycin distributions to this age group may conserve resources and result in less antimicrobial resistance, which is a potential advantage in areas with hypoendemic trachoma and limited resources. Objective: To determine the efficacy of mass azithromycin distributions to preschool-aged children as a strategy for trachoma elimination in areas with hypoendemic disease. Design, Setting, and Participants: In this cluster randomized clinical trial performed from November 23, 2014, until July 31, 2017, thirty rural communities in Niger were randomized at a 1:1 ratio to biannual mass distributions of either azithromycin or placebo to children aged 1 to 59 months. Participants and study personnel were masked to treatment allocation. Data analyses for trachoma outcomes were performed from October 19, 2021, through June 10, 2022. Interventions: Every 6 months, a single dose of either oral azithromycin (20 mg/kg using height-based approximation for children who could stand or weight calculation for small children) or oral placebo was provided to all children aged 1 to 59 months. Main Outcomes and Measures: Trachoma was a prespecified outcome of the trial, assessed as the community-level prevalence of trachomatous inflammation-follicular and trachomatous inflammation-intense through masked grading of conjunctival photographs from a random sample of 40 children per community each year during the 2-year study period. A secondary outcome was the seroprevalence of antibodies to C trachomatis antigens. Results: At baseline, 4726 children in 30 communities were included; 1695 children were enrolled in 15 azithromycin communities and 3031 children were enrolled in 15 placebo communities (mean [SD] proportions of boys, 51.8% [4.7%] vs 52.0% [4.2%]; mean [SD] age, 30.8 [2.8] vs 30.6 [2.6] months). The mean coverage of study drug for the 4 treatments was 79% (95% CI, 75%-83%) in the azithromycin group and 82% (95% CI, 79%-85%) in the placebo group. The mean prevalence of trachomatous inflammation-follicular at baseline was 1.9% (95% CI, 0.5%-3.5%) in the azithromycin group and 0.9% (95% CI, 0-1.9%) in the placebo group. At 24 months, trachomatous inflammation-follicular prevalence was 0.2% (95% CI, 0-0.5%) in the azithromycin group and 0.8% (95% CI, 0.2%-1.6%) in the placebo group (incidence rate ratio adjusted for baseline: 0.18 [95% CI, 0.01-1.20]; permutation P = .07). Conclusions and Relevance: The findings of this trial do not show that biannual mass azithromycin distributions to preschool-aged children were more effective than placebo, although the underlying prevalence of trachoma was low. The sustained absence of trachoma even in the placebo group suggests that trachoma may have been eliminated as a public health problem in this part of Niger. Trial Registration: ClinicalTrials.gov Identifier: NCT02048007.

Performance of SARS-CoV-2 Antigens in a Multiplex Bead Assay for Integrated Serological Surveillance of Neglected Tropical and Other Diseases.

Serosurveillance can provide estimates of population-level exposure to infectious pathogens and has been used extensively during the COVID-19 pandemic. Simultaneous, serological testing for multiple pathogens can be done using bead-based immunoassays to add value to disease-specific serosurveys. We conducted a validation of four SARS-CoV-2 antigens-full-length spike protein, two receptor binding domain proteins, and the nucleocapsid protein-on our existing multiplex bead assay (MBA) for enteric diseases, malaria, and vaccine preventable diseases. After determining the optimal conditions for coupling the antigens to microsphere beads, the sensitivity and specificity of the assay were determined on two instruments (Luminex-200 and MAGPIX) when testing singly (monoplex) versus combined (multiplex). Sensitivity was assessed using plasma from 87 real-time reverse transcription polymerase chain reaction (rRT-PCR) positive persons collected in March-May of 2020 and ranged from 94.3% to 96.6% for the different testing conditions. Specificity was assessed using 98 plasma specimens collected prior to December 2019 and plasma from 19 rRT-PCR negative persons and ranged from 97.4% to 100%. The positive percent agreement was 93.8% to 97.9% using 48 specimens collected > 21 days post-symptom onset, while the negative percent agreement was ≥ 99% for all antigens. Test performance was similar using monoplex or multiplex testing. Integrating SARS-CoV-2 serology with other diseases of public health interest could add significant value to public health programs that have suffered severe programmatic setbacks during the COVID-19 pandemic.

Post-Validation Survey in Two Districts of Morocco after the Elimination of Trachoma as a Public Health Problem.

Trachoma is the leading infectious cause of blindness. In 2016, Morocco was validated by WHO as having eliminated trachoma as a public health problem. We evaluated two previously endemic districts in Morocco for trachomatous inflammation-follicular (TF), trachomatous trichiasis (TT), and antibodies against Chlamydia trachomatis, the causative agent of trachoma. Community-based cross-sectional surveys in the districts of Boumalene Dades and Agdez included 4,445 participants for whom both questionnaire and serology data were available; 58% were aged 1-9 years. Participants had eyes examined for TF and blood collected for analysis of antibodies to the C. trachomatis antigen Pgp3 by both a multiplex bead assay (MBA) and lateral flow assay (LFA). Seroconversion rates (SCR) per 100 people per year were used to estimate changes in the force of infection using Bayesian serocatalytic models. In Agdez, TF prevalence in 1-9-year-olds was 0.3%, seroprevalence ranged from 9.4% to 11.4%, and SCR estimates ranged from 2.4 to 3.0. In Boumalene Dades, TF prevalence in 1-9-year-olds was 0.07%, and modeling data from the different assays indicated a decrease in transmission between 20 and 24 years ago. The TF data support an absence of active trachoma in the two districts examined. However, seroprevalence and SCR in younger people were higher in Agdez than Boumalene Dades, showing that there can be differences in serology metrics in areas with similar TF prevalence. Data will be included in multicountry analyses to better understand potential thresholds for serological surveillance in trachoma.