Dramatic declines in seropositivity as determined with crude extracts of Plasmodium falciparum schizonts between 2000 and 2010 in Dielmo and Ndiop, Senegal

BACKGROUND: Programmes of pre-elimination of malaria have been implemented in Senegal since 2010, and the burden of malaria has decreased substantially. These changes in the epidemiology should be monitored with effective tools that allow changes in patterns of transmission to be estimated. In Dielmo and Ndiop, two villages of Senegal with different malaria endemicity, infections have been followed longitudinally for 20 years, during which time there have been several control interventions leading to substantial decreases of transmission. This study aimed to compare malaria antibody responses of the inhabitants of these two villages, between 2000 and 2010, using schizont crude extracts of a local strain of P. falciparum (Pf Sch07/03). METHODS: Sera collected from inhabitants of the two villages (141 from Dielmo and 79 from Ndiop in 2000; 143 from Dielmo and 79 from Ndiop in 2010) were used to assess the prevalence of antibodies against crude schizont extracts of Pf Sch07/03. Three ages groups were defined: [5-9] yrs, [10-14] yrs and [15-19] yrs. Statistical comparisons were performed. Seroprevalence and the magnitude of antibody responses were compared between age groups, villages and periods. RESULTS: Overall seroprevalence to P.fSch07/03 decreased between 2000 and 2010 in both villages: from 94.4% to 44.4% in Dielmo and from 74.4% to 34.6% in Ndiop. The difference between Dielmo and Ndiop was highly significant in 2000 (p0.20). The decrease in seroprevalence was larger in younger (more than 40%) than older (less than 19%) inhabitants. Longitudinal monitoring of the younger group showed that seroprevalence decreased between 2000 and 2010 in Dielmo from 98.7 to 79.3, but not in Ndiop from 67.6 to 66.7. The magnitude of antibody responses in seropositive individuals was significantly higher in 2000 than 2010 for both villages. CONCLUSIONS: Crude extracts of P. falciparum are appropriate tools for evaluating malaria prevalence at different periods, and in both low and high endemic area. Using crude extracts from local strains to assess transmission may allow efficient evaluation of the consequences of control programs on malaria transmission

Zika virus causes supernumerary foci with centriolar proteins and impaired spindle positioning

International audienceZika virus (ZIKV) causes congenital microcephaly. Although ZIKV can impair cell cycle progression and provoke apoptosis, which probably contributes to disease aetiology through depletion of neural progenitor cells, additional cellular mechanisms may be important. Here, we investigated whether ZIKV infection alters centrosome number and spindle positioning, because such defects are thought to be at the root of inherited primary autosomal recessive microcephaly (MCPH). In addition to HeLa cells, in which centrosome number and spindle positioning can be well monitored, we analysed retinal epithelial cells (RPE-1), as well as brain-derived microglial (CHME-5) and neural progenitor (ReN) cells, using immunofluorescence. We established that ZIKV infection leads to supernumerary foci containing centriolar proteins that in some cases drive multipolar spindle assembly, as well as spindle positioning defects in HeLa, RPE-1 and CHME-5 cells, but not in ReN cells. We uncovered similar phenotypes in HeLa cells upon infection with dengue virus (DENV-2), another flavivirus that does not target brain cells and does not cause microcephaly. We conclude that infection with Flaviviridae can increase centrosome numbers and impair spindle positioning, thus potentially contributing to microcephaly in the case of Zika

Violence chez les jeunes à Dakar : contexte, les facteurs et les réponses - rapport technique no. 2

Le contexte de la recrudescence de la violence chez les jeunes en milieu urbain, à Dakar notamment, justifie cette recherche. Or, au Sénégal, on dispose encore de peu de connaissances sur le phénomène et l'efficacité des réponses développées jusque-là. Les liens existant entre la violence, les situations socioéconomiques, l’exclusion et le cadre de vie urbain font rarement l’objet de production scientifique. Aussi, les réponses officielles des pouvoirs publics, les stratégies de résilience développées par les jeunes eux-mêmes, en particulier les jeunes filles, pour faire face aux situations de violence, d’exclusion et d’injustice ne sont pas documentées et connues

Aedes Aegypti saliva enhances chikungunya virus replication in human skin fibroblasts via inhibition of the type I interferon signaling pathway

International audienc

Zika virus: epidemiology, clinical features and host-virus interactions

International audienceVery recently, Zika virus (ZIKV) has gained a medical importance following the large-scale epidemics in South Pacific and Latin America.This paper reviews information on the epidemiology and clinical features of Zika disease with a particular emphasis on the host-virus in-teractions that contribute to the pathogenicity of ZIKV in human

Association of high Plasmodium falciparum parasite densities with polyclonal microscopic infections in asymptomatic children from Toubacouta, Senegal

Abstract Background Malaria is a leading cause of mortality and morbidity in tropical countries, especially in sub-Saharan Africa. In Senegal, a control plan implemented in the beginning of the 2000s has enabled a substantial reduction of mortality and morbidity due to malaria. However, eradication of malaria requires a vaccine that protects against Plasmodium falciparum the deadliest species of the parasite that causes this disease. Plasmodium falciparum is characterized by an extensive genetic diversity that makes vaccine development challenging. In this study, the diversity of P. falciparum isolates was analysed from asymptomatic children residing in the district of Toubacouta, Senegal. Methods A nested PCR approach was used to perform genotyping of the msp-1 and msp-2 loci in samples from 87 asymptomatic children infected with P. falciparum, collected during a cross sectional survey in November and December 2010. Parasite densities in blood samples were determined by microscopic examination and statistical analyses were used to identify association of parasite genotype and parasitaemia. Results Genotyping was successful in 84/87 and 82/87 samples for msp-1 and msp-2, respectively. A strong genetic diversity was found with a total of 15 and 21 different alleles identified for msp-1 and msp-2, respectively. RO33 was the most frequent allelic family of msp-1 followed by MAD20, then by K1. Regarding msp-2 allelic families, 3D7 was more common than FC27. Multiple infections were predominant, since 69% and 89% of the samples genotyped for msp-1 and msp-2 showed more than one clone of P. falciparum with complexity of infection (COI) of 2.5 and 4.7, respectively. Expected heterozygosity (HE) was 0.57 and 0.55 for msp-1 and msp-2, respectively. Interestingly, polyclonal infections were significantly associated with higher parasitaemia. Conclusions The strong genetic diversity of P. falciparum clones and the association of polyclonal infection with high parasitaemia call for a multi-allelic approach in the design of vaccine candidates for efficient malaria eradication

African and Asian Zika virus strains differentially induce early antiviral responses in primary human astrocytes

International audienceZIKA virus (ZIKV) is a newly emerging arbovirus. Since its discovery 60years ago in Uganda, it has spread throughout the Pacific, Latin America and the Caribbean, emphasizing the capacity of ZIKV to spread to non-endemic regions worldwide. Although infection with ZIKV often leads to mild disease, its recent emergence in the Americas has coincided with an increase in adults developing Guillain-Barré syndrome and neurological complications in new-borns, such as congenital microcephaly. Many questions remain unanswered regarding the complications caused by different primary isolates of ZIKV. Here, we report the permissiveness of primary human astrocytes for two clinically relevant, Asian and African ZIKV strains and show that both isolates strongly induce antiviral immune responses in these cells albeit with markedly different kinetics. This study describes for the first time the specific antiviral gene expression in infected primary human astrocytes, the major glial cells within the central nervous system