Impact of annual praziquantel treatment on urogenital schistosomiasis in a seasonal transmission focus in central Senegal

In Sub-Saharan Africa, urogenital schistosomiasis remains a significant public health problem, causing 150.000 deaths/year with approximately 112 million cases diagnosed. The Niakhar district is a disease hotspot in central Senegal where transmission occurs seasonally with high prevalences. The aim of this study was to determine the effect of annual treatment over 3 years on the seasonal transmission dynamics of S. haematobium in 9 villages in the Niakhar district. Adults and children aged between 5 and 60 years were surveyed from 2011 to 2014. Urine samples were collected door-to-door and examined for S. haematobium eggs at baseline in June 2011, and all participants were treated in August 2011 with PZQ (40 mg/kg). After this initial examination, evaluations were conducted at 3 successive time points from September 2011 to March 2014, to measure the efficacy of the annual treatments and the rates of reinfection. Each year, during the transmission period, from July to November-December, malacological surveys were also carried out in the fresh water bodies of each village to evaluate the infestation of the snail intermediate hosts. At baseline, the overall prevalence of S. haematobium infection was 57.7%, and the proportion of heavy infection was 45.3%, but one month after the first treatment high cure rates (92.9%) were obtained. The overall infection prevalence and proportion of heavy infection intensities were drastically reduced to 4.2% and 2.3%, respectively. The level of the first reinfection in February-March 2012 was 9.5%. At follow-up time points, prevalence levels varied slightly between reinfection and treatment from 9.5% in June 2012 to 0.3% in March 2013, 11.2 in June 2013, and 10.1% April 2014. At the end of the study, overall prevalence was significantly reduced from 57.7% to 10.1%. The overall rate of infested Bulinid snails was reduced after repeated treatment from 0.8% in 2012 to 0.5% in 2013. Repeated annual treatments are suggested to have a considerable impact on the transmission dynamics of S. haematobium in Niakhar, due to the nature of the epidemiological system with seasonal transmission. Thus, to maintain this benefit and continue to reduce the morbidity of urogenital schistosomiasis, other approaches should be integrated into the strategy plans of the National program to achieve the goal of urogenital schistosomiasis elimination in seasonal foci in Senegal

Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes

The file attached is the Published/publisher’s pdf version of the article.Copyright: © 2013 Webster et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Interactions between Schistosoma haematobium group species and their Bulinus spp. intermediate hosts along the Niger River Valley

Background Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is endemic in Niger but complicated by the presence of Schistosoma bovis, Schistosoma curassoni and S. haematobium group hybrids along with various Bulinus snail intermediate host species. Establishing the schistosomes and snails involved in transmission aids disease surveillance whilst providing insights into snail-schistosome interactions/compatibilities and biology. Methods Infected Bulinus spp. were collected from 16 villages north and south of the Niamey region, Niger, between 2011 and 2015. From each Bulinus spp., 20–52 cercariae shed were analysed using microsatellite markers and a subset identified using the mitochondrial (mt) cox1 and nuclear ITS1 + 2 and 18S DNA regions. Infected Bulinus spp. were identified using both morphological and molecular analysis (partial mt cox1 region). Results A total of 87 infected Bulinus from 24 sites were found, 29 were molecularly confirmed as B. truncatus, three as B. forskalii and four as B. globosus. The remaining samples were morphologically identified as B. truncatus (n = 49) and B. forskalii (n = 2). The microsatellite analysis of 1124 cercariae revealed 186 cercarial multilocus genotypes (MLGs). Identical cercarial genotypes were frequently (60%) identified from the same snail (clonal populations from a single miracidia); however, several (40%) of the snails had cercariae of different genotypes (2–10 MLG’s) indicating multiple miracidial infections. Fifty-seven of the B. truncatus and all of the B. forskalii and B. globosus were shedding the Bovid schistosome S. bovis. The other B. truncatus were shedding the human schistosomes, S. haematobium (n = 6) and the S. haematobium group hybrids (n = 13). Two B. truncatus had co-infections with S. haematobium and S. haematobium group hybrids whilst no co-infections with S. bovis were observed. Conclusions This study has advanced our understanding of human and bovid schistosomiasis transmission in the Niger River Valley region. Human Schistosoma species/forms (S. haematobium and S. haematobium hybrids) were found transmitted only in five villages whereas those causing veterinary schistosomiasis (S. bovis), were found in most villages. Bulinus truncatus was most abundant, transmitting all Schistosoma species, while the less abundant B. forskalii and B. globosus, only transmitted S. bovis. Our data suggest that species-specific biological traits may exist in relation to co-infections, snail-schistosome compatibility and intramolluscan schistosome development

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

A Development Consensus reconciling the Beijing Model and Washington Consensus: Views and Agenda

Reconciling the two dominant development models of the Washington Consensus (WC) and Beijing Model (BM) remains a critical challenge in the literature. The challenge is even more demanding when emerging development paradigms like the Liberal Institutional Pluralism (LIP) and New Structural Economics (NSE) schools have to be integrated. While the latter has recognized both State and market failures but failed to provide a unified theory, the former has left the challenging concern of how institutional diversity matter in the development process. We synthesize perspectives from over 150 recently published papers on development and Sino-African relations in order to present the relevance of both the WC and BM in the long-term and short-run respectively. While the paper provides a unified theory by reconciling the WC and the BM to complement the NSE, it at the same time presents a case for economic rights and political rights as short-run and long-run development priorities respectively. By reconciling the WC with the BM, the study contributes at the same to macroeconomic NSE literature of unifying a development theory and to the LIP literature on institutional preferences with stages of development. Hence, the proposed reconciliation takes into account the structural and institutional realities of nations at difference stages of the process of development

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Coexistence de Nématodes Trichostrongyloides chez des Marsupiaux de Guyane

Analyse de l’helminthofaune de deux Didelphis marsupialis comparée à celle faite par Durette-Desset, 1974, chez un Metachirops opossum de la même région. Bien que l’équilibre général soit assez comparable, les différences entre les deux Marsupiaux sont sensibles, l’espèce dominante, en particulier, n’est pas la même. La localisation des espèces communes ou des espèces vicariantes est stable. (Contrairement aux premières notions acquises à ce sujet, il apparaît que la faune est constituée d’une seule et même lignée, à l’exception des Moennigia, qui seraient des captures provenant des Xenarthes)

<em>Bulinus forskalii</em> (Basommatophore: Planorbidae), New Experimental Intermediate Host of Trematoda <em>Paramphistomum microbothrium</em> Fischoeder 1901

The objective of this study was to gain a better knowledge of the biological cycle of Paramphistomum microbothrium in order to develop effective control strategies. The adult specimens of P. microbothrium were gathered alive from the stomach mucous membrane of cattle (Bos taurus) at Kolda slaughterhouses. Then they were put in Petri dishes containing distilled water for egg laying. The majority of eggs hatched at day 19 and gave miracidiae which were used to infest artificially 75 infestation-free Bulinus forskalii (hatched and raised in the laboratory). These started to produce cercariae four weeks after infestation. The success rate of Bulinus forskalii infestation was 34.67% and the real percentage of infestation was 35.29%. The produced cercariae were encysted in metacercariae before being given to four young cattle, which were subjected to fecal samplings and, later, sacrificed for postmortem examination. Each animal received a single dose of 500 metacercariae at 2, 3, 4 and 5 weeks of maturation, respectively. No eggs of P. microbothrium were found in the feces of the animals during the six months of postinfection monitoring. Adult forms of P. microbothrium were found in the rumen of the four sacrificed cattle. Success rates were 62.6, 69.0, 83.8 and 56.4% for cattle infested with metacercariae aged 2, 3, 4 and 5 weeks after maturation, respectively. B. forskalii can thus be considered as a good experimental intermediate host of P. microbothrium

Disposition des organites argyrophiles superficiels du miracidium et de la cercaire de

Les formations argyrophiles superficielles du miracidium et de la cercaire de P. phillerouxi Dinnik, 1961, sont décrites en détail. Celles du miracidium sont identiques par leur nombre et leur disposition aux formations observées chez quelques miracidiums d’autres espèces du genre. Par contre la chétotaxie de la cercaire diffère de celle de la cercaire de P. togolense (Albaret et coll., 1978) et paraît donc constituer un bon critère pour la taxonomie de ce groupe