Until recently, the epidemiology and control of schistosomiasis in sub-Saharan Africa have focused primarily on infections in school-aged children and to a lesser extent on adults. Now there is growing evidence and reports of infection in infants and pre-school-aged children (≤ 6 years old) in Ghana, Kenya, Mali, Niger, Nigeria and Uganda, with reported prevalence from 14% to 86%. In this review, we provide available information on the epidemiology, transmission and control of schistosomiasis in this age group, generally not considered or included in national schistosomiasis control programmes that are being implemented in several sub-Saharan African countries. Contrary to previous assumptions, we show that schistosomiasis infection starts from early childhood in many endemic communities and factors associated with exposure of infants and pre-school-aged children to infection are yet to be determined. The development of morbidity early in childhood may contribute to long-term clinical impact and severity of schistosomiasis before they receive treatment. Consistently, these issues are overlooked in most schistosomiasis control programmes. It is, therefore, necessary to review current policy of schistosomiasis control programmes in sub-Saharan Africa to consider the treatment of infant and pre-school-aged children and the health education to mothers.

BackgroundThe acceleration of the control of soil-transmitted helminth (STH) infections in Nigeria, emphasizing preventive chemotherapy, has become imperative in light of the global fight against neglected tropical diseases. Predictive risk maps are an important tool to guide and support control activities.MethodologySTH infection prevalence data were obtained from surveys carried out in 2011 using standard protocols. Data were geo-referenced and collated in a nationwide, geographic information system database. Bayesian geostatistical models with remotely sensed environmental covariates and variable selection procedures were utilized to predict the spatial distribution of STH infections in Nigeria.Principal FindingsWe found that hookworm, Ascaris lumbricoides, and Trichuris trichiura infections are endemic in 482 (86.8%), 305 (55.0%), and 55 (9.9%) locations, respectively. Hookworm and A. lumbricoides infection co-exist in 16 states, while the three species are co-endemic in 12 states. Overall, STHs are endemic in 20 of the 36 states of Nigeria, including the Federal Capital Territory of Abuja. The observed prevalence at endemic locations ranged from 1.7% to 51.7% for hookworm, from 1.6% to 77.8% for A. lumbricoides, and from 1.0% to 25.5% for T. trichiura. Model-based predictions ranged from 0.7% to 51.0% for hookworm, from 0.1% to 82.6% for A. lumbricoides, and from 0.0% to 18.5% for T. trichiura. Our models suggest that day land surface temperature and dense vegetation are important predictors of the spatial distribution of STH infection in Nigeria. In 2011, a total of 5.7 million (13.8%) school-aged children were predicted to be infected with STHs in Nigeria. Mass treatment at the local government area level for annual or bi-annual treatment of the school-aged population in Nigeria in 2011, based on World Health Organization prevalence thresholds, were estimated at 10.2 million tablets.Conclusions/SignificanceThe predictive risk maps and estimated deworming needs presented here will be helpful for escalating the control and spatial targeting of interventions against STH infections in Nigeria.

Background Achatina fulica, the giant African snail, is the largest terrestrial mollusk species. Owing to its voracious appetite, wide environmental adaptability, high growth rate, and reproductive capacity, it has become an invasive species across the world, mainly in Southeast Asia, Japan, the western Pacific islands, and China. This pest can damage agricultural crops and is an intermediate host of many parasites that can threaten human health. However, genomic information of A. fulica remains limited, hindering genetic and genomic studies for invasion control and management of the species.FindingsUsing a k-mer–based method, we estimated the A. fulica genome size to be 2.12 Gb, with a high repeat content up to 71%. Roughly 101.6 Gb genomic long-read data of A. fulica were generated from the Pacific Biosciences sequencing platform and assembled to produce a first A. fulica genome of 1.85 Gb with a contig N50 length of 726 kb. Using contact information from the Hi-C sequencing data, we successfully anchored 99.32% contig sequences into 31 chromosomes, leading to the final contig and scaffold N50 length of 721 kb and 59.6 Mb, respectively. The continuity, completeness, and accuracy were evaluated by genome comparison with other mollusk genomes, BUSCO assessment, and genomic read mapping. A total of 23,726 protein-coding genes were predicted from the assembled genome, among which 96.34% of the genes were functionally annotated. The phylogenetic analysis using whole-genome protein-coding genes revealed that A. fulica separated from a common ancestor with Biomphalaria glabrata ∼182 million years ago.ConclusionTo our knowledge, the A. fulica genome is the first terrestrial mollusk genome published to date. The chromosome sequence of A. fulica will provide the research community with a valuable resource for population genetics and environmental adaptation studies for the species, as well as investigations of the chromosome-level of evolution within mollusks.