Prevalence and risk factors associated with urogenital schistosomiasis among primary school pupils in Nigeria.

Urogenital schistosomiasis is a neglected tropical disease that is endemic to Nigeria and one which continues to pose a public health problem especially among school-age children in rural communities. This study was carried out in remote areas where most people depend on natural water bodies and rainwater for their daily water needs. The present research investigates the prevalence of urogenital schistosomiasis and the significant risk factors associated with the infection among primary school children in Nigeria. From August 2019 to December 2019, a total of 5514 primary school-age children from twelve sites were diagnosed with the presence of Schistosoma haematobium eggs in their urine. Socio-demographic, sociocultural, and socioeconomic indices and data on behaviors (e.g contact frequency with freshwater bodies) were also collected for each diagnosed individual through the use of a questionnaire. Associations between each of these variables and disease infection were tested using a multivariate logistic regression. A total of 392 of the 5514-urine samples were positive for the infection, the overall prevalence reached 7.1% and ranged from 4.6% (East Nigeria) to 15,9% (West Nigeria). Multivariate logistic regression analyses showed that the significant risk factors associated with S. haematobium infection are frequent contact with freshwater bodies (rivers/steams), with an adjusted odds ratio (AOR) of 4.92; 3.34-7.24, washing/swimming, AOR: 46.49; 27.64-78.19, and fishing, AOR: 11.57; 8.74-15.32. For socioeconomic factors, primary education of fathers which resulted in an AOR of 1.63; 1.01-2.45 was significantly associated with the infection. The socio-demographic factor for the 12-14 year age group had an AOR of 1.68; 1.21-2.33, and was also significantly associated with the disease. Nigeria remains endemic for urogenital schistosomiasis as indicated by the data obtained from all the studied sites, and it is clear that efforts need to be intensified in order to control and eradicate the disease throughout the country.

Pyrenean ptarmigans decline under climatic and human influences through the Holocene.

In Europe, the Quaternary is characterized by climatic fluctuations known to have led to many cycles of contraction and expansion of species geographical ranges. In addition, during the Holocene, historical changes in human occupation such as colonization or abandonment of traditional land uses can also affect habitats. These climatically or anthropically induced geographic range changes are expected to produce considerable effective population size change, measurable in terms of genetic diversity and organization. The rock ptarmigan (Lagopus muta) is a small-bodied grouse occurring throughout Northern hemispheric arctic and alpine tundra. This species is not considered threatened at a continental scale, but the populations in the Pyrenees are of concern because of their small population size, geographical isolation and low genetic diversity. Here, we used 11 microsatellites to investigate genetic variations and differentiations and infer the overall demographic history of Pyrenean rock ptarmigan populations. The low genetic variability found in these populations has been previously thought to be the result of a bottleneck that occurred following the last glacial maximum (i.e., 10,000 years ago) or more recently (i.e., during the last 200 years). Our results clearly indicate a major bottleneck affecting the populations in the last tenth of the Holocene. We discuss how this decline can be explained by a combination of unfavorable and successive events that increased the degree of habitat fragmentation.

Invasive species threat: parasite phylogenetics reveals patterns and processes of host-switching between non-native and native captive freshwater turtles.

One of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. In this context, the role of parasites is not negligible as it may enhance the success of invaders. The red-eared slider, Trachemys scripta elegans, has been globally considered among the worst invasive species. Since its introduction through the pet trade, T. s. elegans is now widespread and represents a threat for indigenous species. Because T. s. elegans coexists with Emys orbicularis and Mauremys leprosa in Europe, it has been suggested it may compete with the native turtle species and transmit pathogens. We examined parasite transfer from American captive to the two native species that co-exist in artificial pools of a Turtle Farm in France. As model parasite species we used platyhelminth worms of the family Polystomatidae (Monogenea) because polystomes have been described from American turtles in their native range. Phylogenetic relationships among polystomes parasitizing chelonian host species that are geographically widespread show patterns of diversification more complex than expected. Using DNA barcoding to identify species from adult and/or polystome eggs, several cases of host switching from exotic to indigenous individuals were illustrated, corroborating that parasite transmission is important when considering the pet trade and in reintroduction programmes to reinforce wild populations of indigenous species.

Transferability of microsatellite markers among economically and ecologically important galliform birds.

We used the partially sequenced genomes of the turkey and chicken to find a large number of microsatellite markers. We then characterized 10 polymorphic microsatellite markers developed by cross-species amplification from economically and ecologically important birds to various European sub-species of the grey partridge. Even though we used cross-species amplification, a high degree of polymorphism was conserved in all microsatellite markers. Cross-species amplification from birds of economic and ecological interest, such as chicken and turkey, could be an attractive approach to develop microsatellite markers and to use these to manage wild and captive populations of other galliforms, such as the grey partridge.

Cheap, rapid and efficient DNA extraction method to perform multilocus microsatellite genotyping on all Schistosoma mansoni stages.

Schistosomes are endoparasites causing a serious human disease called schistosomiasis. The quantification of parasite genetic diversity is an essential component to understand the schistosomiasis epidemiology and disease transmission patterns. In this paper, we propose a novel assay for a rapid, low costly and efficient DNA extraction method of egg, larval and adult stages of Schistosoma mansoni. One euro makes possible to perform 60,000 DNA extraction reactions at top speed (only 15 min of incubation and 5 handling steps).

Cheap, rapid and efficient DNA extraction method to perform multilocus microsatellite genotyping on all Schistosoma mansoni stages

Schistosomes are endoparasites causing a serious human disease called schistosomiasis. The quantification of parasite genetic diversity is an essential component to understand the schistosomiasis epidemiology and disease transmission patterns. In this paper, we propose a novel assay for a rapid, low costly and efficient DNA extraction method of egg, larval and adult stages of Schistosoma mansoni. One euro makes possible to perform 60,000 DNA extraction reactions at top speed (only 15 min of incubation and 5 handling steps).

The use of MapPop1.0 for choosing a QTL mapping sample from an advanced backcross population.

QTL detection is a good way to assess the genetic basis of quantitative traits such as the plant response to its environment, but requires large mapping populations. Experimental constraints, however, may require a restriction of the population size, risking a decrease in the quality level of QTL mapping. The purpose of this paper was to test if an advanced backcross population sample chosen by MapPop 1.0 could limit the effect of size restriction and improve the QTL detection when compared to random samples. We used the genotypic and phenotypic data obtained for 280 genotypes, considered as the reference population. The "MapPop sample" of 100 genotypes was first compared to the reference population, and genetic maps, genotypic and phenotypic data and QTL results were analysed. Despite the increase in donor allele frequency in the MapPop sample, this did not lead to an increase of the genetic map length or a biased phenotypic distribution. Three QTL among the 10 QTL found in the reference population were also detected in the MapPop sample. Next, the MapPop sample results were compared to those from 500 random samples of the same size. The main conclusion was that the MapPop software avoided the selection of biased samples and the detection of false QTL and appears particularly interesting to select a sample from an unbalanced population.

Gene discovery and expression analysis of immune-relevant genes from Biomphalaria glabrata hemocytes.

The immune effector cells (hemocytes) of the snail host Biomphalaria glabrata are known to play a key role in recognition and elimination of larval helminths such as the human blood fluke Schistosoma mansoni. To identify novel immune-relevant genes, we undertook an expressed sequence tag program. A hemocyte cDNA library was constructed using snails that were not exposed to a particular pathogen or parasite but maintained in non-axenic conditions. Putative function could be assigned to 53% of the 1613 high quality cDNAs analysed. Based on sequence similarities, we identified 31 immune-relevant genes corresponding either to cellular defence effectors, proteases and protease inhibitors, pattern recognition receptors, cell adhesion molecules or immune regulators. In order to further investigate the potential involvement of these genes in snail-trematode immunobiological interactions, we analysed their expression in unchallenged and parasite-challenged snails, using the immunosuppressive trematode Echinostoma caproni and snail strains selected for resistance or susceptibility to this parasite. Real-time PCR analysis of expression ratios at 7 time-points post-exposure revealed both (i) genes displaying constitutive expression differences between the two strains; and (ii) genes differentially modulated after parasite exposure.

Schistosoma mansoni and Echinostoma caproni excretory-secretory products differentially affect gene expression in Biomphalaria glabrata embryonic cells.

Biomphalaria glabrata embryonic (Bge) cells have been shown to be a valuable in vitro cellular model for the study of snail host-parasite interactions. They both promote the growth and differentiation of various trematode species including Schistosoma mansoni, and Echinostoma caproni and share some morphological and functional features with circulating haemocytes. As an approach to investigate snail genes potentially regulated following exposure to trematode excretory-secretory (ES) products, we compared gene expression profiles of Bge cells exposed to saline solution, or saline solution containing ES products from S. mansoni or E. caproni, two trematode species parasitizing B. glabrata. Following differential display RT-PCR analysis we characterized 23 differentially displayed cDNAs and we focussed on the 5 cDNAs showing sequence similarity to known genes for expression validation. Using RT-PCR, we confirmed that ES products from S. mansoni and E. caproni differentially affect the expression levels of 4 out of the 5 transcripts. These partial transcripts corresponded to novel B. glabrata sequences, and showed significant sequence similarity to genes coding for (i) cytochrome C, (ii) methyl-binding proteins, (iii) glutamine synthetases, and (iv) protease inhibitors from the Kunitz family. The possible significance of these gene expression changes in host-parasite molecular interactions is discussed.