[Early effect of vaccination on the positivity rate of salivary tests performed on nursing home staff in the Walloon Region]. / Face à la COVID-19. Effet précoce de la vaccination sur le taux de positivité des tests salivaires réalisés chez le personnel des maisons de repos en Région wallonne.

In Belgium, nursing homes (NH) were disproportionately affected by the SARS-CoV-2 pandemic. The objective of this study was to compare the risk of SARS-CoV-2 infection in vaccinated and unvaccinated staff members. METHODS: This was a prospective cohort study conducted between February 1 and April 02, 2021, in 99 nursing homes (NHs) in the Walloon Region, a few weeks after the start of the vaccination campaign. A mixed-effects logistic regression analysis was performed to assess the relationship between COVID results of molecular tests on saliva samples of the NHs' staff and their vaccination status. RESULTS: Only 32 (0,1 %) of 39 267 saliva tests were positive. Logistic analysis showed that unvaccinated nursing home staff were 4 times more likely to develop COVID-19 than vaccinated staff during the study period. CONCLUSION: This study demonstrated an early decreased risk of infection in vaccinated NHs staff. Saliva tests were designed to be convenient, less expensive and non-invasive, and could be considered as an alternative to nasopharyngeal tests.

En Belgique, les maisons de repos ont été touchées de manière disproportionnée par la pandémie de SARS-CoV-2. L'objectif de cette étude était de comparer le risque d'infection par le SARS-CoV-2 chez les membres du personnel vaccinés et non vaccinés. Méthodes : Il s'agit d'une étude de cohorte prospective qui s'est déroulée entre le 1er février et le 02 avril 2021 dans 99 maisons de repos (MR) en Région wallonne, quelques semaines après le début de la campagne de vaccination. Une analyse de régression logistique à effets mixtes a été effectuée pour évaluer la relation entre les résultats COVID des tests moléculaires sur des échantillons de salive du personnel des maisons de repos et leur statut vaccinal. Résultats : Seuls 32 (0,1 %) des 39.267 tests salivaires étaient positifs. L'analyse logistique montre que le personnel des maisons de repos non vacciné était 4 fois plus susceptible de développer la COVID-19 que le personnel vacciné pendant la période d'étude. Conclusion : cette étude a mis en évidence une réduction précoce du risque d'infection chez le personnel vacciné des maisons de repos. Les tests salivaires ont été conçus pour être pratiques, moins coûteux et non invasifs, ils pourraient être considérés comme une alternative aux tests nasopharyngés.

Population trends of seabirds in Mexican Islands at the California Current System.

The Baja California Pacific Islands (BCPI) is a seabird hotspot in the southern California Current System supporting 129 seabird breeding populations of 23 species and over one million birds annually. These islands had a history of environmental degradation because of invasive alien species, human disturbance, and contaminants that caused the extirpation of 27 seabird populations. Most of the invasive mammals have been eradicated and colonies have been restored with social attraction techniques. We have recorded the number of breeding pairs annually for most of the colonies since 2008. To assess population trends, we analyzed these data and show results for 19 seabird species on ten island groups. The maximum number of breeding pairs for each nesting season was used to estimate the population growth rate (λ) for each species at every island colony. We performed a moving block bootstrap analysis to assess whether seabird breeding populations are increasing or decreasing. San Benito, Natividad, and San Jerónimo are the top three islands in terms of abundance of breeding pairs. The most widespread species is Cassin's Auklet (Ptychoramphus aleuticus) with 14 colonies. Thirty-one populations of 14 species are significantly increasing while eleven populations of seven species are decreasing. We did not find statistical significance for 19 populations, however, 15 have λ>1 which suggest they are growing. Twelve of the 18 species for which we estimated a regional population trend are significantly increasing, including seven surface-nesting species: Brandt's Cormorant (Phalacrocorax penicillatus), Brown Pelican (Pelecanus occidentalis), Caspian Tern (Hydroprogne caspia), Double-crested Cormorant (P. auritus), Elegant Tern (Thalasseus elegans), Laysan Albatross (Phoebastria immutabilis) and Western Gull (Larus occidentalis), and five burrow-nesting species: Ainley's (Hydrobates cheimomnestes), Ashy (H. homochroa) and Townsend's (H. socorroensis) Storm-Petrels, and Craveri's (Synthliboramphus craveri) and Guadalupe (S. hypoleucus) Murrelets. The BCPI support between 400,000 and 1.4 million breeding individuals annually. Our results suggest that these islands support healthy and growing populations of seabirds that have shown to be resilient to extreme environmental conditions such as the "Blob", and that such resilience has been strengthen from conservation and restoration actions such as the eradication of invasive mammals, social attraction techniques and island biosecurity.

A Mouse Immunogenicity Model for the Evaluation of Meningococcal Conjugate Vaccines.

The identification of an appropriate animal model for use in the development of meningococcal vaccines has been a challenge as humans are the only natural host for Neisseria meningitidis. Small animal models have been developed and are widely used to study the efficacy or immunogenicity of vaccine formulations generated against various diseases. Here, we describe the development and optimization of a mouse model for assessing the immunogenicity of candidate tetravalent meningococcal polysaccharide (MenACYW-TT) protein conjugate vaccines. Three inbred (BALB/c [H-2d], C3H/HeN [H-2k], or C57BL/6 [H-2b]) and one outbred (ICR [H-2g7]) mouse strains were assessed using serial two-fold dose dilutions (from 2 µg to 0.03125 µg per dose of polysaccharide for each serogroup) of candidate meningococcal conjugate vaccines. Groups of 10 mice received two doses of the candidate vaccine 14 days apart with serum samples obtained 14 days after the last dose for the evaluation of serogroup-specific anti-polysaccharide IgG by ELISA and bactericidal antibody by serum bactericidal assay (SBA). C3H/HeN and ICR mice had a more dose-dependent antibody response to all four serogroups than BALB/c and C57Bl/6 mice. In general, ICR mice had the greatest antibody dose-response range (both anti-polysaccharide IgG and bactericidal antibodies) to all four serogroups and were chosen as the model of choice. The 0.25 µg per serogroup dose was chosen as optimal since this was in the dynamic range of the serogroup-specific dose-response curves in most of the mouse strains evaluated. We demonstrate that the optimized mouse immunogenicity model is sufficiently sensitive to differentiate between conjugated polysaccharides, against unconjugated free polysaccharides and, to degradation of the vaccine formulations. Following optimization, this optimized mouse immunogenicity model has been used to assess the impact of different conjugation chemistries on immunogenicity, and to screen and stratify various candidate meningococcal conjugate vaccines to identify those with the most desirable profile to progress to clinical trials.

Characteristics of Travel-Related Severe Plasmodium vivax and Plasmodium falciparum Malaria in Individuals Hospitalized at a Tertiary Referral Center in Lima, Peru.

Severe Plasmodium falciparum malaria is uncommon in South America. Lima, Peru, while not endemic for malaria, is home to specialized centers for infectious diseases that admit and manage patients with severe malaria (SM), all of whom contracted infection during travel. This retrospective study describes severe travel-related malaria in individuals admitted to one tertiary care referral hospital in Lima, Peru; severity was classified based on criteria published by the World Health Organization in 2000. Data were abstracted from medical records of patients with SM admitted to Hospital Nacional Cayetano Heredia from 2006 to 2011. Of 33 SM cases with complete clinical data, the mean age was 39 years and the male/female ratio was 2.8. Most cases were contracted in known endemic regions within Peru: Amazonia (47%), the central jungle (18%), and the northern coast (12%); cases were also found in five (15%) travelers returning from Africa. Plasmodium vivax was most commonly identified (71%) among the severe infections, followed by P. falciparum (18%); mixed infections composed 11% of the group. Among the criteria of severity, jaundice was most common (58%), followed by severe thrombocytopenia (47%), hyperpyrexia (32%), and shock (15%). Plasmodium vivax mono-infection predominated as the etiology of SM in cases acquired in Peru.

Insecticide Resistance in Areas Under Investigation by the International Centers of Excellence for Malaria Research: A Challenge for Malaria Control and Elimination.

Scale-up of the main vector control interventions, residual insecticides sprayed on walls or structures and/or impregnated in bed nets, together with prompt diagnosis and effective treatment, have led to a global reduction in malaria transmission. However, resistance in vectors to almost all classes of insecticides, particularly to the synthetic pyrethroids, is posing a challenge to the recent trend of declining malaria. Ten International Centers of Excellence for Malaria Research (ICEMR) located in the most malaria-endemic regions of the world are currently addressing insecticide resistance in the main vector populations, which not only threaten hope for elimination in malaria-endemic countries but also may lead to reversal where notable reductions in malaria have been documented. This communication illustrates the current status of insecticide resistance with a focus on the countries where activities are ongoing for 9 out of the 10 ICEMRs. Most of the primary malaria vectors in the ICEMR countries exhibit insecticide resistance, albeit of varying magnitude, and spanning all mechanisms of resistance. New alternatives to the insecticides currently available are still to be fully developed for deployment. Integrated vector management principles need to be better understood and encouraged, and viable insecticide resistance management strategies need to be developed and implemented.

Population structure and spatio-temporal transmission dynamics of Plasmodium vivax after radical cure treatment in a rural village of the Peruvian Amazon.

BACKGROUND: Despite the large burden of Plasmodium vivax, little is known about its transmission dynamics. This study explored the population structure and spatio-temporal dynamics of P. vivax recurrent infections after radical cure in a two-year cohort study carried out in a rural community of the Peruvian Amazon. METHODS: A total of 37 P. vivax participants recruited in San Carlos community (Peru) between April and December 2008 were treated radically with chloroquine and primaquine and followed up monthly for two years with systematic blood sampling. All samples were screened for malaria parasites and subsequently all P. vivax infections genotyped using 15 microsatellites. Parasite population structure and dynamics were determined by computing different genetic indices and using spatio-temporal statistics. RESULTS: After radical cure, 76% of the study participants experienced one or more recurrent P. vivax infections, most of them sub-patent and asymptomatic. The parasite population displayed limited genetic diversity (He = 0.49) and clonal structure, with most infections (84%) being monoclonal. Spatio-temporal clusters of specific haplotypes were found throughout the study and persistence of highly frequent haplotypes were observed over several months within the same participants/households. CONCLUSIONS: In San Carlos community, P. vivax recurrences were commonly observed after radical treatment, and characterized by asymptomatic, sub-patent and clustered infections (within and between individuals from a few neighbouring households). Moreover low genetic diversity as well as parasite inbreeding are likely to define a clonal parasite population which has important implications on the malaria epidemiology of the study area.

Malaria in selected non-Amazonian countries of Latin America.

Approximately 170 million inhabitants of the American continent live at risk of malaria transmission. Although the continent's contribution to the global malaria burden is small, at least 1-1.2 million malaria cases are reported annually. Sixty percent of the malaria cases occur in Brazil and the other 40% are distributed in 20 other countries of Central and South America. Plasmodium vivax is the predominant species (74.2%) followed by P. falciparum (25.7%) and P. malariae (0.1%), and no less than 10 Anopheles species have been identified as primary or secondary malaria vectors. Rapid deforestation and agricultural practices are directly related to increases in Anopheles species diversity and abundance, as well as in the number of malaria cases. Additionally, climate changes profoundly affect malaria transmission and are responsible for malaria epidemics in some regions of South America. Parasite drug resistance is increasing, but due to bio-geographic barriers there is extraordinary genetic differentiation of parasites with limited dispersion. Although the clinical spectrum ranges from uncomplicated to severe malaria cases, due to the generally low to middle transmission intensity, features such as severe anemia, cerebral malaria and other complications appear to be less frequent than in other endemic regions and asymptomatic infections are a common feature. Although the National Malaria Control Programs (NMCP) of different countries differ in their control activities these are all directed to reduce morbidity and mortality by using strategies like health promotion, vector control and impregnate bed nets among others. Recently, international initiatives such as the Malaria Control Program in Andean-country Border Regions (PAMAFRO) (implemented by the Andean Organism for Health (ORAS) and sponsored by The Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM)) and The Amazon Network for the Surveillance of Antimalarial Drug Resistance (RAVREDA) (sponsored by the Pan American Health Organization/World Health Organization (PAHO/WHO) and several other partners), have made great investments for malaria control in the region. We describe here the current status of malaria in a non-Amazonian region comprising several countries of South and Central America participating in the Centro Latino Americano de Investigación en Malaria (CLAIM), an International Center of Excellence for Malaria Research (ICEMR) sponsored by the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases (NIAID).

[Evaluation of rapid diagnostic tests for malaria in Colombia as an integral part of the disease control strategy]. / Evaluación de la aplicación de pruebas de diagnóstico rápido para malaria como parte de una estrategia integral para su control en Colombia.

INTRODUCTION: The Andean Health Organization has been responsible for the coordination and evaluation of the malaria rapid diagnostic test strategy. This undertaking was organized to strengthen the malaria diagnostic capacity in ten provinces of Colombia. OBJECTIVE: The implementation cycle of malaria rapid diagnostic tests was evaluated, along with its impact, performance, usage and coverage under the project "Malaria control in bordering areas of the Andean Region: a community cpproach" (PAMAFRO), as an integral part of the malaria control strategy. MATERIALS AND METHODS: A descriptive retrospective study was organized in two stages. The first stage was an evaluation of the implementation of the rapid diagnostic test cycle. The second stage evaluated indicators of impact, performance, usage and coverage of this strategy. These evaluations were conducted from October 2007 to July 2008 in 10 Andean provinces of Colombia. A multi-criteria scoring method was applied to determine the critical variables. RESULTS: The compliance in the implementation cycle for rapid diagnostic tests was 71%. Planning was the weakest component of the cycle with 50% of the goals accomplished. The critical variables with low compliance were as follows: study of rapid diagnostic test needs in the country (50%), study of rapid diagnostic test needs in each province (50%), rapid diagnostic test distribution according to needs (50%), assessment of health workers performance (50%), compliance with temperature and humidity requirements for storage of the rapid diagnostic tests at the provincial level (50%), logistics (67%) and supervision (25%). CONCLUSION: Implementation strategies are important to strengthen the critical variables found asociated with low compliance.

Evaluación de la aplicación de pruebas de diagnóstico rápido para malaria como parte de una estrategia integral para su control en Colombia / Evaluation of rapid diagnostic tests for malaria in Colombia as an integral part of the disease control strategy

Introducción. El Organismo Andino de la Salud coordinó y evaluó la estrategia de aplicación de pruebas de diagnóstico rápido de malaria para fortalecer el diagnóstico de esta enfermedad en diez departamentos de Colombia. Objetivo. Evaluar el ciclo de implementación, impacto, resultado, uso y cobertura de la aplicación de las pruebas de diagnóstico rápido en el ámbito del proyecto Control de la malaria en zonas fronterizas de la Región Andina: un enfoque comunitario (PAMAFRO), como parte de una estrategia integral para el control de la malaria. Materiales y métodos. En un estudio descriptivo retrospectivo, se evaluó el ciclo de implementación del uso de las pruebas de diagnóstico rápido, primera etapa, y los indicadores de resultado, uso y cobertura de la estrategia, segunda etapa, durante el periodo de octubre de 2007 a julio de 2008. Se aplicó el análisis multicriterio, método de puntaje para determinar las variables críticas. Resultados. El cumplimiento del ciclo de implementación fue de 71 %, y la planeación fue el componente más débil del ciclo, con un cumplimiento del 50 %. Se determinaron como variables críticas y con bajo cumplimiento las siguientes: estudio de las necesidades de pruebas de diagnóstico rápido en el país (50 %), estudio de necesidades en los departamentos (50 %), distribución de las pruebas según las necesidades (50 %), evaluación del desempeño de los trabajadores de salud (50 %), cumplimiento de directrices sobre temperatura y humedad de las pruebas en el nivel departamental (50 %), logística (50 %) y supervisión (25 %). Conclusiones. Es importante que en futuras estrategias de aplicación de pruebas de diagnóstico rápido en el país, se fortalezcan las variables críticas de bajo cumplimiento encontradas en el presente estudio.

Introduction. The Andean Health Organization has been responsible for the coordination and evaluation of the malaria rapid diagnostic test strategy. This undertaking was organized to strengthen the malaria diagnostic capacity in ten provinces of Colombia. Objective. The implementation cycle of malaria rapid diagnostic tests was evaluated, along with its impact, performance, usage and coverage under the project “Malaria control in bordering areas of the Andean Region: a community cpproach (PAMAFRO), as an integral part of the malaria control strategy. Materials and methods. A descriptive retrospective study was organized in two stages. The first stage was an evaluation of the implementation of the rapid diagnostic test cycle. The second stage evaluated indicators of impact, performance, usage and coverage of this strategy. These evaluations were conducted from October 2007 to July 2008 in 10 Andean provinces of Colombia. A multi-criteria scoring method was applied to determine the critical variables. Results. The compliance in the implementation cycle for rapid diagnostic tests was 71%. Planning was the weakest component of the cycle with 50% of the goals accomplished. The critical variables with low compliance were as follows: study of rapid diagnostic test needs in the country (50%), study of rapid diagnostic test needs in each province (50%), rapid diagnostic test distribution according to needs (50%), assessment of health workers performance (50%), compliance with temperature and humidity requirements for storage of the rapid diagnostic tests at the provincial level (50%), logistics (67%) and supervision (25%). Conclusion. Implementation strategies are important to strengthen the critical variables found asociated with low compliance.

Field evaluation of a rapid diagnostic test (Parascreen) for malaria diagnosis in the Peruvian Amazon.

BACKGROUND: The rapid diagnostic tests for malaria (RDT) constitute a fast and opportune alternative for non-complicated malaria diagnosis in areas where microscopy is not available. The objective of this study was to validate a RDT named Parascreen under field conditions in Iquitos, department of Loreto, Peru. Parascreen is a RDT that detects the histidine-rich protein 2 (HRP2) antigen from Plasmodium falciparum and lactate deshydrogenase from all Plasmodium species. METHODS: Parascreen was compared with microscopy performed by experts (EM) and polymerase chain reaction (PCR) using the following indicators: sensitivity (Se), specificity (Sp), positive (PV+) and negative predictive values (PV-), positive (LR+) and negative likehood ratio (LR-). RESULTS: 332 patients with suspected non-complicated malaria who attended to the MOH health centres were enrolled between October and December 2006. For P. falciparum malaria, Parascreen in comparison with EM, had Se: 53.5%, Sp: 98.7%, PV+: 66.7%, PV-: 97.8%, LR+: 42.27 and LR-: 0.47; and for non-P. falciparum malaria, Se: 77.1%, Sp: 97.6%, PV+: 91.4%, PV-: 92.7%, LR+: 32.0 and LR-: 0.22. The comparison of Parascreen with PCR showed, for P. falciparum malaria, Se: 81.8%, Sp: 99.1%, PV+: 75%, PV-: 99.4, LR+: 87.27 and LR-: 0.18; and for non-P. falciparum malaria Se: 76.1%, Sp: 99.2%, PV+: 97.1%, PV-: 92.0%, LR+: 92.51 and LR-: 0.24. CONCLUSIONS: The study results indicate that Parascreen is not a valid and acceptable test for malaria diagnosis under the field conditions found in the Peruvian Amazon. The relative proportion of Plasmodium species, in addition to the genetic characteristics of the parasites in the area, must be considered before applying any RDT, especially after the finding of P. falciparum malaria parasites lacking pfhrp2 gene in this region.

Mejora en el diagnóstico y tratamiento oportuno de malaria con el uso de pruebas rápidas por promotores de salud en la Amazonía Peruana / Improvements in timely malaria diagnosis and appropriate therapy with the use of rapid tests by health promoters in Peruvian Amazon jungle

Objetivos. Comparar la oportunidad en el diagnóstico y tratamiento apropiado de la malaria antes y después de la incorporación del uso de pruebas rápidas por promotores de salud en comunidades periféricas de Iquitos. Material y métodos. Estudio longitudinal con evaluación pre y postintervención. En ambas evaluaciones se recolectó un número mínimo de 200 pacientes febriles (casos sospechosos de malaria) que habían sido atendidos por el promotor en las seis semanas previas, datos relacionados a la oportunidad en el diagnóstico y tratamiento, y los diagnósticos confirmatorios por gota gruesa. Resultados. Con la intervención hubo una disminución significativadel tiempo transcurrido entre el inicio de síntomas y el inicio del tratamiento de 110 horas (4,6 días) a 46,3 horas (1,9 días) (p menor que0,001). Dicha variación fue debida mayormente a la reducción del tiempo transcurrido desde la consulta al promotor hasta la obtención del diagnóstico del paciente, de 69 horas (2,9 días) a sólo 20 minutos (p menor que 0,001). Además, hubo un incremento significativo de la proporción de pacientes con malaria que recibieron tratamiento antimalárico oportuno de 15,5 a 54,9 por ciento (p menor que 0,001), la proporción de pacientes con malaria que recibieron tratamiento apropiado a la especie del parásito de 26,7 por ciento a 83,5 por ciento (p menor que 0,001) y la proporción de pacientes conmalaria falciparum que recibieron tratamiento apropiado de 5,3 a 73,1 por ciento (p mneor que 0,001). Conclusiones. A través de la incorporación del uso de pruebas rápidas por promotores de salud en las comunidades seleccionadas, se ha mejorado la oportunidad en el diagnóstico y tratamiento apropiado de la malaria.

Objectives. To compare the achievement of a timely diagnosis and appropriate therapy for malaria before and after the incorporation of rapid tests for diagnosing this disease used by health promoters in peripheral communities in Iquitos. Material and methods. Alongitudinal study with pre- and post- intervention assessments was performed. Two hundred febrile patients (suspected malaria cases) seen by health promoters during the last 6 weeks were selected, and data related to a timely malaria diagnosis and therapy, as well as confirmatory diagnoses using thick smears was collected. Results. There was a significant decrease in the time elapsed from symptom onset to therapy initiation with the intervention, from 110 hours (4.6 days) to 46,3 hours (1.9 days) (p minor that 0.001). This variation was mainly due to a reduction of the time since the patient was first seen by a health promoter until the time when a diagnosis was achieved, from 69 hours (2.9 days) to only 20 minutes (p minor that 0.001). There was also a significant increase in the frequency of malaria patients who received timely antimalarial therapy, from 1,5 per cent to 54,9 per cent (p minor that0.001); the proportion of malaria patients receiving appropriate therapy according to the parasite species increased from 26.7 per cent to 83.5 per cent (p minor that 0.001), and the proportion of P. falciparum malaria patients who received appropriate therapy rose from 5.3 per cent to 73.1 per cent (p minor that 0.001). Conclusions. Now it is possible to achieve a timely diagnosis and appropriate therapy formalaria with the use of rapid tests by health promoters in these selected communities.

Construction of designer glycoconjugate vaccines with size-specific oligosaccharide antigens and site-controlled coupling.

Coupling of carbohydrate antigens to protein carriers is a typical approach to enhancing the immunogenicity of carbohydrate-based vaccines. Glycoconjugates with well-defined structures are needed for studies defining the structural variables that govern antibody responses. We report a chemical strategy for preparation of an array of glycoconjugates containing saccharides of desired molecular sizes by selective depolymerization of bacterial polysaccharides and chemically controlled site-specific coupling. As an example, we synthesized and evaluated an oligosaccharide-based vaccine against type III group B Streptococcus.