African meningitis belt pneumococcal disease epidemiology indicates a need for an effective serotype 1 containing vaccine, including for older children and adults

<p>Abstract</p> <p>Background</p> <p>Pneumococcal conjugate vaccine strategies in GAVI-eligible countries are focusing on infant immunization but this strategy may not be optimal in all settings. We aimed to collect all available population based data on pneumococcal meningitis throughout life in the African meningitis belt and then to model overall meningitis risk to help inform vaccine policy.</p> <p>Methods</p> <p>After a systematic review of literature published from 1970 through the present, we found robust population-based <it>Streptococcus pneumoniae </it>(Sp) meningitis data across age strata for four African meningitis belt countries that included 35 surveillance years spanning from 1970 to 2005. Using these data we modeled disease risk for a hypothetical cohort of 100,000 persons followed throughout life.</p> <p>Results</p> <p>Similar to meningococcal meningitis, laboratory-confirmed pneumococcal meningitis was seasonal, occurring primarily in the dry season. The mean annual Sp meningitis incidence rates were 98, 7.8 to 14, and 5.8 to 12 per 100,000 among persons <1, 1 through 19, and 20 to 99 years of age, respectively, which (in the absence of major epidemics) were higher than meningococcal meningitis incidences for persons less than 1 and over 20 years of age. Mean Sp meningitis case fatality ratios (CFR) among hospitalized patients ranged from 36-66% depending on the age group, with CFR exceeding 60% for all age groups beyond 40 years; depending on the age group, Sp meningitis mortality incidences were 2 to 12-fold greater than those for meningococcal meningitis. The lifetime risks of pneumococcal meningitis disease and death were 0.6% (1 in 170) and 0.3% (1 in 304), respectively. The incidences of these outcomes were highest among children age <1 year. However, the cumulative risk was highest among persons age 5 to 59 years who experienced 59% of pneumococcal meningitis outcomes. After age 5 years and depending on the country, 59-79% of meningitis cases were caused by serotype 1.</p> <p>Conclusions</p> <p>In the African meningitis belt, Sp is as important a cause of meningitis as <it>Neisseria meningitidis</it>, particularly among older children and working age adults. The meningitis belt population needs an effective serotype 1 containing vaccine and policy discussions should consider vaccine use outside of early childhood.</p

Влияние инфляции на взаимосвязь стабилизации и роста экономики некоторых стран Восточной Европы и бывшего СССР

In many countries, particularly in sub-Saharan Africa, Demographic and Health Surveys (DHSs) are the main way of estimating HIV prevalence nationally in the general population. Some DHSs record the longitude and latitude of the survey clusters.We present three methodological approaches for mapping spatial variations in HIV prevalence using the DHSs. These approaches are applied to simulated DHS samplings from a model country. The estimated surfaces are then compared with the model’s initial surface.We demonstrate that a method using kernel estimators with adaptive bandwidths size of equal number of persons observed can be used to estimate the main regional trends in epidemics. Application to Burkina Faso’s 2003 DHS data provides a plausible image of that country’s epidemiological situation

Prévalences des Parasites Intestinaux Humains Chez les Patients du Service de Parasitologie de l’INRSP Bamako de 2010 à 2015

Introduction: L’invasion de l’appareil digestif humain par les parasites est le motif de consultation de plusieurs patients à l’Institut National de Recherche en Santé Publique (INRSP). Objectifs : Il s’agissait de déterminer la prévalence des parasites intestinaux humains chez les patients reçus au laboratoire de parasitologie de l’INRSP pendant la période de 2010 à 2015. Ce qui permettra de mesurer l’impact de l’amélioration de la situation sanitaire sur la transmission des parasites intestinaux au sein de la population humaine de la ville de Bamako. Méthodologie : C’était une étude rétrospective basée sur les résultats portés dans les registres de laboratoire. Résultats : Au total, 1833 individus sur 3815 patients étaient positifs aux infections intestinales parasitaires. Une prévalence de 44% a été obtenue chez les sujets féminins contre 42,2% chez les patients masculins. Les tranches d’âges de 1 à 10 ans et ceux de 11 à 20 ans étaient plus infectés avec 46,5%. L’ethnie Bambara avait le plus élevé taux d’infection (46%) et les Tamasheks avaient le plus bas taux (30%), alors que les élèves et étudiants avec 46,5% étaient la couche socio-professionnelle la plus infectée. Les douleurs abdominales étaient les plus fréquents signes cliniques. Entamoeba histolytica, 72% et Giardia intestinalis, 15,4% étaient les espèces parasitaires les plus fréquentes. Conclusion : Une diminution progressive de la proportion des sujets infectés allant de 52,2% en 2010 à 29,0% en 2015 a été constatée. Cela démontre un effet positif des efforts déployés par le gouvernement pour l’amélioration des conditions sanitaires à Bamako. Introduction: The invasion of the human digestive tract by parasites is the reason of several patients’ visits at the National Institute for Research in Public Health (INRSP). Objectives: The aim was to determine the prevalence of human intestinal parasites in patients admitted to the INRSP parasitology laboratory during the period from 2010 to 2015. That can enable to measure the impact of health situation improvement on the transmission of intestinal parasites in the human population in Bamako. Methodology: This was a retrospective study based on the information reported in the laboratory note books records. Results: A total of 1,833 individuals out of 3815 patients were detected positive. A prevalence of 44% was obtained in female subjects and 42.2% in male patients. The age groups 1-10 and 11-20 were more infected with 46.5%. Bambara ethnic group had the highest infection rate (46%) and the Tamasheks had the lowest rate (30%), while school kids and students were the most infected socio-professional group with 46.5%. Abdominal pain was the most common clinical signs. Entamoeba histolytica, 72% and Giardia intestinalis, 15.4% were the most common parasite species. Conclusion: A gradual decrease in the proportion of infected people ranging from 52.2% in 2010 to 29.0% in 2015 was found. This demonstrates a positive effect of the efforts made by the government to improve health conditions in Bamako

Efficacité d’une prise unique de Praziquantel pour le traitement de la bilharziose urinaire en zones endémiques chez les enfants d'âge scolaire au Mali

Au Mali, la schistosomiase est un problème de santé publique comme dans tous les 42 paysafricains sur 76 concernés dans le monde, avec 230 millions de personnes infectées sur 800 millions de personnes exposées et plus de 800 000 décès annuels. L’objectif de cette étude était de tester l’efficacité d’une dose unique de Plaziquantel pour traiter les enfants d’âge scolaire de 11 villages maliens situés en zones endémiques de la schistosomiase urinaire. Après assentiment ou consentement, l’enregistrement des volontaires âgés de cinq ans ou plus a été fait. Après dépistage systématique de l’ensemble des volontaires pour savoir la prévalence de l’infection avant traitement, une dose unique de Praziquantel a été donnée aux sujets infectés. Un mois après la prise du médicament, un second dépistage a été fait chez les mêmes volontaires afin de mesurer l’effet du traitement. La technique de filtration de l'urine pour la détection de l'excrétion des œufs de schistosomiase a été utilisée comme méthode de diagnostic. Sur 549 volontaires testés à l’enregistrement (397 féminins et 152 masculins), 9,1% (51/549) étaient infectés par S. haematobium. Un mois après le traitement à la dose unique de Praziquantel, un taux de réduction significatif de 3,5% (P= 0,03) a été constaté. Cette étude a montré que le Praziquantel reste toujours efficace pour le traitement de la schistosomiase urinaire. Le maintien de ce produit comme molécule distribuée pour le traitement de masse du programme national de lutte contre la schistosomiase est justifié. &nbsp; In Mali, schistosomiasis is a public health problem as in all 42 African countries out of 76 affected worldwide, with 230 million people infected in 800 million people exposed and more than 800 000 annual deaths. The objective of this study was to test the efficiency of a single dose of Plaziquantel to treat school-age children in 11 Malian villages located in endemic areas of urinary schistosomiasis. After consent, the enrolment of volunteers greater than 5 years old was done. After systematic screening of all volunteers for the prevalence of infection before treatment, a single dose of Praziquantel was given to infected individuals. One month after drug administration, a second screening was done among the same volunteers to measure the treatment effect. The technique of schistosomiasis eggs detection by urine filtration was used as a diagnostic method. From the screening including 549 volunteers (397 females and 152 males), 9.1% (51/549) were positives to S. haematobiuminfection. One month after treatment with a single dose of Praziquantel, a significant rate reduction (3.5%, P= 0.03) was observed. This study showed that Praziquantel is still effective for the treatment of urinary schistosomiasis. The choice of this drug by the national schistosomiasis control program for community mass treatment was justified

The contribution of aestivating mosquitoes to the persistence of Anopheles gambiae in the Sahel

<p>Abstract</p> <p>Background</p> <p>Persistence of African anophelines throughout the long dry season (4-8 months) when no surface waters are available remains one of the enduring mysteries of medical entomology. Recent studies demonstrated that aestivation (summer diapause) is one mechanism that allows the African malaria mosquito, <it>Anopheles gambiae</it>, to persist in the Sahel. However, migration from distant localities - where reproduction continues year-round - might also be involved.</p> <p>Methods</p> <p>To assess the contribution of aestivating adults to the buildup of populations in the subsequent wet season, two villages subjected to weekly pyrethrum sprays throughout the dry season were compared with two nearby villages, which were only monitored. If aestivating adults are the main source of the subsequent wet-season population, then the subsequent wet-season density in the treated villages will be lower than in the control villages. Moreover, since virtually only M-form <it>An. gambiae </it>are found during the dry season, the reduction should be specific to the M form, whereas no such difference is predicted for S-form <it>An. gambiae </it>or <it>Anopheles arabiensis</it>. On the other hand, if migrants arriving with the first rain are the main source, no differences between treated and control villages are expected across all members of the <it>An. gambiae </it>complex.</p> <p>Results</p> <p>The wet-season density of the M form in treated villages was 30% lower than that in the control (P < 10^-4, permutation test), whereas no significant differences were detected in the S form or <it>An</it>. <it>arabiensis</it>.</p> <p>Conclusions</p> <p>These results support the hypothesis that the M form persist in the arid Sahel primarily by aestivation, whereas the S form and <it>An. arabiensis </it>rely on migration from distant locations. Implications for malaria control are discussed.</p

Knowledge, beliefs and practices regarding prevention of bacterial meningitis in Burkina Faso, 5 years after MenAfriVac mass campaigns.

BACKGROUND: To adapt communications concerning vaccine prevention, we studied knowledge, beliefs and practices around meningitis risk and prevention in a young adult population in Burkina Faso in 2016, 5 years after the MenAfriVac® mass campaign and one year before the vaccine's inclusion in the infant immunization schedule. METHODS: In a representative sample of the population aged 15 to 33 years (N = 220) in Bobo-Dioulasso, Burkina Faso, study nurses administered a standardized paper questionnaire consisting of predominantly open questions, collecting information on meningitis risk factors and prevention, and on exposure to dry air and kitchen fire smoke. We identified themes and analyzed their frequency. We created a meningitis knowledge score (range 0 to 4) based on pre-defined best responses and analyzed the determinants of knowledge score levels ≥2 (basic score) and ≥3 (high score) using multivariate logistic regression. RESULTS: Biomedically supported facts and good practices were known by the majority of participants (eg vaccine prevention, 84.5%). Younger women aged 15-20 years had a higher frequency of low scores <2 (17.0%) compared to older women aged 21-33 years (6.3%) and men of both age groups (3.8%). Junior secondary School attendance explained the differences between the two groups of women, the gender gap for the older, but not the young women, and explained score differences among young women. Local understandings and practices for risk and prevention were commonly reported and used (risk from unripe mango consumption and prevention through nasal application of shea nut butter). DISCUSSION: This study shows a gender gap in knowledge of meningitis risk and prevention, largely due to education-level inequalities. Women below 21 years had particularly low levels of knowledge and may need interventions outside schools and perinatal care. Our study suggests a strong adherence to local understandings of and practices around meningitis risk and prevention, which should be taken into account by vaccination promotion

Aestivation of the African Malaria Mosquito, Anopheles gambiae in the Sahel

The African malaria mosquito, Anopheles gambiae, inhabits diverse environments including dry savannas, where surface waters required for larval development are absent for 4–8 months per year. Under such conditions, An. gambiae virtually disappears. Whether populations survive the long dry season by aestivation (a dormant state promoting extended longevity during the summer) or are reestablished by migrants from distant locations where larval sites persist has remained an enigma for over 60 years. Resolving this question is important, because fragile dry season populations may be more susceptible to control. Here, we show unequivocally that An. gambiae aestivates based on a demographic study and a mark release–recapture experiment spanning the period from the end of one wet season to the beginning of the next. During the dry season, An. gambiae was barely detectable in Sahelian villages of Mali. Five days after the first rain, before a new generation of adults could be produced, mosquito abundance surged 10-fold, implying that most mosquitoes were concealed locally until the rain. Four days after the first rain, a marked female An. gambiae s.s. was recaptured. Initially captured, marked, and released at the end of the previous wet season, she has survived the 7-month-long dry season. These results provide evidence that An. gambiae persists throughout the dry season by aestivation and open new questions for mosquito and parasite research. Improved malaria control by targeting aestivating mosquitoes using existing or novel strategies may be possible

Diversity, composition, altitude, and seasonality of high-altitude windborne migrating mosquitoes in the Sahel: Implications for disease transmission

Recent studies have reported Anopheles mosquitoes captured at high-altitude (40–290 m above ground) in the Sahel. Here, we describe this migration modality across genera and species of African Culicidae and examine its implications for disease transmission and control. As well as Anopheles, six other genera—Culex, Aedes, Mansonia, Mimomyia, Lutzia, and Eretmapodites comprised 90% of the 2,340 mosquitoes captured at altitude. Of the 50 molecularly confirmed species (N = 2,107), 33 species represented by multiple specimens were conservatively considered high-altitude windborne migrants, suggesting it is a common migration modality in mosquitoes (31–47% of the known species in Mali), and especially in Culex (45−59%). Overall species abundance varied between 2 and 710 specimens/species (in Ae. vittatus and Cx. perexiguus, respectively). At altitude, females outnumbered males 6:1, and 93% of the females have taken at least one blood meal on a vertebrate host prior to their departure. Most taxa were more common at higher sampling altitudes, indicating that total abundance and diversity are underestimated. High-altitude flight activity was concentrated between June and November coinciding with availability of surface waters and peak disease transmission by mosquitoes. These hallmarks of windborne mosquito migration bolster their role as carriers of mosquito-borne pathogens (MBPs). Screening 921 mosquitoes using pan-Plasmodium assays revealed that thoracic infection rate in these high-altitude migrants was 2.4%, providing a proof of concept that vertebrate pathogens are transported by windborne mosquitoes at altitude. Fourteen of the 33 windborne mosquito species had been reported as vectors to 25 MBPs in West Africa, which represent 32% of the MBPs known in that region and include those that inflict the heaviest burden on human and animal health, such as malaria, yellow fever, dengue, and Rift Valley fever. We highlight five arboviruses that are most likely affected by windborne mosquitoes in West Africa: Rift Valley fever, O'nyong'nyong, Ngari, Pangola, and Ndumu. We conclude that the study of windborne spread of diseases by migrating insects and the development of surveillance to map the sources, routes, and destinations of vectors and pathogens is key to understand, predict, and mitigate existing and new threats of public health

Molecular Characteristics and Epidemiology of Meningococcal Carriage, Burkina Faso, 2003

Meningococcal serogroups are genetically diverse and short-lived in the African meningitis belt

Estimating the Force of Infection for Dengue Virus Using Repeated Serosurveys, Ouagadougou, Burkina Faso.

Because of limited data on dengue virus in Burkina Faso, we conducted 4 consecutive age-stratified longitudinal serologic surveys, ≈6 months apart, among persons 1-55 years of age, during June 2015-March 2017, which included a 2016 outbreak. The seroconversion rate before the serosurvey enrollment was estimated by binomial regression, taking age as the duration of exposure, and assuming constant force of infection (FOI) over age and calendar time. We calculated FOI between consecutive surveys and rate ratios for potentially associated characteristics based on seroconversion using the duration of intervals. Among 2,897 persons at enrollment, 66.3% were IgG-positive, and estimated annual FOI was 5.95%. Of 1,269 enrollees participating in all 4 serosurveys, 438 were IgG-negative at enrollment. The annualized FOI ranged from 10% to 20% (during the 2016 outbreak). Overall, we observed high FOI for dengue. These results could support decision-making about control and preventive measures for dengue