Short report: Semi-quantitative scoring of an immunochromatographic test for circulating filarial antigen

The value of a semi-quantitative scoring of the filarial antigen test (Binax Now Filariasis card test, ICT) results was evaluated during a field survey in. the Republic of Congo. One hundred and thirty-four (134) of 774 tests (17.3%) were clearly positive and were scored 1, 2, or 3; and 11 (1.4%) had questionable results. Wuchereria bancrofti microfilariae (mf) were detected in 41 of those 133 individuals with an ICT test score 1 who also had a night blood smear; none of the 11 individuals with questionable ICT results harbored night mf. Cuzick's test showed a significant trend for higher microfilarial densities in groups with higher ICT scores (P < 0.001). The ICT scores were also significantly correlated with blood mf counts. Because filarial antigen levels provide an indication of adult worm infection intensity, our results suggest that semi-quantitative reading of the ICT may be useful for grading the intensity of filarial infections in individuals and populations

Evidence of variability in the structure and recruitment of rhizospheric and endophytic bacterial communities associated with arable sweet sorghum (Sorghum bicolor (L) Moench)

Sorghum is the second most cultivated crop in Africa and is a staple food source of many African communities. Exploiting the associated plant growth promoting bacteria (PGPB) has potential as an agricultural biotechnology strategy to enhance sorghum growth, yield and nutritional properties. Here we use Terminal-Restriction Fragment Length Polymorphism (TRFLP) and Denaturing Gradient Gel Electrophoresis (DGGE) to evaluate the factors that potentially shape rhizospheric and endophytic bacterial communities associated with sorghum farmed in South Africa. Microbial diversity was typically higher in the rhizosphere and rhizoplane compared to the endophytic zones (root, shoot and stem). Geographical location was one of the main drivers in describing microbial community assemblages found in rhizospheric and endophytic sorghum-linked niches. NO3-N, total nitrogen and pH were clearly identified as the main abiotic factors shaping sorghum-associated soil communities. Our results also suggest that specific bacterial taxa with potential N-fixing capacities (Acetobacter sp., Azospirillum sp., Pantoea sp., Bacillus sp. and cyanobacteria) are consistently detected in sorghum-created rhizospheric and endophytic environments, irrespective of environmental factor effects.The South African National Research Foundation (NRF)http://link.springer.com/journal/11104hb2016Genetic

The impact of two semiannual treatments with albendazole alone on lymphatic filariasis and soil-transmitted helminth infections: A community-based study in the Republic of Congo

Implementation of mass drug administration (MDA) with ivermectin plus albendazole (ALB) for lymphatic filariasis (LF) has been delayed in central Africa because of the risk of serious adverse events in subjects with high Loa loa microfilaremia. We conducted a community trial to assess the impact of semiannual MDA with ALB (400 mg) alone on LF and soil-transmitted helminth (STH) infections in the Republic of Congo. Evaluation at 12 months showed that ALB MDA had not significantly reduced Wuchereria bancrofti antigenemia or microfilaria (mf) rates in the community (from 17.3% to 16.6% and from 5.3% to 4.2%, respectively). However, the geometric mean mf count in mf-positive subjects was reduced from 202.2 to 80.9 mf/mL (60% reduction, P = 0.01). The effect of ALB was impressive in 38 subjects who were mf-positive at baseline and retested at 12 months: 37% had total mf clearance, and individual mf densities were reduced by 73.0%. MDA also dramatically reduced the hookworm infection rate in the community from 6.5% to 0.6% (91% reduction), with less impressive effects on Ascaris and Trichuris. These preliminary results suggest that semiannual community MDA with ALB is a promising strategy for controlling LF and STH in areas with coendemic loiasis

Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity

Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana-exposed to more than a decade of regular ivermectin treatment-have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread.Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR.This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations

Prevalence and intensity of human soil transmitted helminth infections in the Akonolinga health district (Centre Region, Cameroon): Are adult hosts contributing in the persistence of the transmission?

Background: Soil-transmitted helminthiases (STHs) are among the most prevalent afflictions of the developing world, with approximately 2 billion people infected worldwide. Heavily infected individuals suffer from severe morbidity that can result in death. These parasitic diseases also impair physical and mental growth in childhood, thwart educational advancement, and hinder economic development. Periodic deworming with Albendazole or Mebendazole of high-risk groups (school-age children, preschool children, and pregnant women) can significantly lower the levels of infections below the threshold associated with morbidity. However, an important proportion of the population (adults) is excluded from this high-risk group treatment based-strategy, and might lead to the persistence of these diseases in endemic areas despite the repeated treatments. The main objective of this study was to evaluate the contribution of this neglected at-risk group in the spread and persistence of STH in Cameroon. Methods: A cross sectional survey was conducted in the Akonolinga health district (Centre Region, Cameroon) to assess the prevalence and intensity of these helminth infections. Stool samples were collected from males and females, aged 18 years and over, and analyzed using the Kato-Katz technique. Results: A total of 334 patients, among which 181 (54.2%) females and 153 (45.8%) males, were examined. The STH of major concern was found in this group of individuals, with overall prevalence equal to 18.0% (95% CI: 14.2–22.4) for Ascaris lumbricoides, 43.7% (95% CI: 38.5–49.1) for Trichuris trichiura, and 7.5% (95% CI: 5.1–10.8) for Necator americanus. Conclusion: This study reveals that STH infections are prevalent in adults in the Akonolinga health district, with moderate to high risk and light intensity of infection. These infected adults might constitute a potential parasite reservoir and a source of dissemination and persistence of these infections, highlighting the need to really take into account this neglected group of individuals in the mass treatment policy

A Second Population-Based Cohort Study in Cameroon Confirms the Temporal Relationship Between Onchocerciasis and Epilepsy

International audienceTo confirm our earlier evidence of a temporal and dose–response relationship between onchocerciasis and epilepsy, we conducted another cohort study in a different setting in Cameroon. Individuals whose Onchocerca volvulus microfilarial density (Ov-MFD) was measured in 1992–1994 when they were children were revisited in 2019 to determine if they acquired epilepsy. With reference to individuals with no microfilariae in 1992–1994, the relative risks of acquiring epilepsy were 0.96, 2.76, 3.67, and 11.87 in subjects with initial Ov-MFD of 1–7, 8–70, 71–200, and > 200 microfilariae per skin snip, respectively. This study further demonstrates reproducibility using the Bradford Hill’s criteria for causality

Impact of Cultivation Area on the Physical, Chemical, and Mechanical Properties of Banana Pseudo-Stems Fibers in Cameroon

Cellulosic fibers were extracted from the pseudo-stem of Musa sapientum cultivated in two different sites in Cameroon. The FBY (Yaounde Banana Fibers) and FBP (Penja Banana Fibers) studied in this work were obtained by a bio-extraction method and characterized. The apparent densities of FBP and FBY were 0.90 ± 0.02 g/cm3 and 1.03 ± 0.04 g/cm3, while the moisture contents were 10.6 ± 0.2% and 12.4 ± 0.3%, respectively. Their chemical compositions were as follows: extracts 15.32% and 17.79%; pectin 5.7% and 14.77%; lignin 10.1% and 9.8%; and cellulose 47.1% and 58.3%, respectively. The water absorption rate at saturation was 140% and 170% by mass and was reached rapidly in the first 30 min of immersion. The tensile strengths of fibers were 743.9 MPa and 730.6 MPa, the elastic moduli were 260 MPa and 242 MPa, and the elongations at break were 2.8% and 2.2%, respectively. From the thermal analysis, the fibers’ stability temperatures were in the neighborhood of 250°C. Only slight differences were noticed in the properties of both fibers. Long outdoor conservation of the banana pseudo-stems before processing provided fibers with properties comparable to the properties of natural fibers reported in the literature. Independently of the harvesting locations, both fibers can be envisaged as cost-cutting fillers in the plastic industry

Additional file 1: Dataset S1. of Loss of sensitivity of immunochromatographic test (ICT) for lymphatic filariasis diagnosis in low prevalence settings: consequence in the monitoring and evaluation procedures

Database for lymphatic filariasis survey in four health districts in the Far North Region of Cameroon (XLS). NA: non applicable; 0: negative; 1: positive. (XLS 92 kb