Search

Six months following the national launch of COVID-19 vaccinations in Cameroon, only 1.1% of the target population was fully vaccinated, with women representing less than one-third of the vaccinated population regardless of age, profession, or comorbidities. Hence, the aim of this study was to understand the low COVID-19 vaccination rate of women in order to enhance vaccine uptake. A cross-sectional study was conducted between July and October 2021 through an online survey. Additionally, a retrospective analysis of the Cameroon Ministry of Public Health (MINSANTE) database of the pandemic (COVID-19) for the period of March 2020 to October 2021 was simultaneously carried out. Our sample consisted of 249 responders aged between 18 and 50 years enrolled in the 10 regions of Cameroon, with 142 (57%) who were female. We assessed factors related to having been vaccinated against COVID-19 and predictors of COVID-19 vaccination among non-vaccinated people. Concerning COVID-19 vaccination, 39.2% were not vaccinated. Non-vaccination was statistically associated with being female, being a healthcare worker, fear of adverse effects, and not believing in the vaccine. In the qualitative analysis, women identified themselves as being anti-COVID-19-vaccine for several reasons, including doubts about the quality or safety of the vaccine; the perception that COVID-19 vaccines are presented as being an obligation; and regarding the multitude of vaccines on the market, the belief that there are "more local" effective alternatives to the vaccine. The implementation of the gender approach to COVID-19 vaccination is one factor influencing its effectiveness and sustainability. [ABSTRACT FROM AUTHOR]

The Douala-Buea Region (DBR; 4°–5°N, 9°–10°30′E), a portion of the southern Cameroon passive margin, developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcano-sedimentary cover, was explored in order to evaluate the lithology and tectonics controls on its landscape using the qualitative and quantitative geomorphological analyses based on 30 m resolution Digital Elevation Models (DEM) and field evidences. This area displays an uneven and complex landscape differentiated into four morphological units: Douala, Nkondjock, Kumba and Buea Units. The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Campo sedimentary basin. The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement. The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau. The Buea Unit corresponds to the Mount Cameroon stratovolcano. The relief analysis through mountain-front sinuosity (Smf, 1.19–1.43) and relative relief ratio (Rr, 0.10–2.31) vary from one unit to another. The drainage network analysis including drainage patterns, stepped longitudinal river profiles, the associated morphometric indexes, notably the concavity index (IC, 0.56–0.88), deviation (D, 267–2912 m), basin asymmetry factor (Af, 6.37–42.12), hypsometric integral (HI, 0.10–0.29), valley floor width to valley height ratio (Vf, 0.36–2.75), elongation ratio (Re, 0.30–0.50), watershed slope (S, 6.88–88.88) and stream length gradient index (SL, 0–3332) vary from one basin to another too. These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics. The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points, asymmetric basins, and fault reactivations, and highlights the tectonics activity that used to occur through the time and their control on the morphology. Together, they document the lithostructural controls on the DBR landscape evolution, extendable in the whole SW Cameroon margin. [ABSTRACT FROM AUTHOR]

Background: Mycobacterium ulcerans is the causative agent of the necrotizing skin disease Buruli ulcer (BU), which has been reported from over 30 countries worldwide. The majority of notified patients come from West African countries, such as Côte d'Ivoire, Ghana, Benin and Cameroon. All clinical isolates of M. ulcerans from these countries are closely related and their genomes differ only in a limited number of single nucleotide polymorphisms (SNPs). Methodology/Principal Findings: We performed a molecular epidemiological study with clinical isolates from patients from two distinct BU endemic regions of Cameroon, the Nyong and the Mapé river basins. Whole genome sequencing of the M. ulcerans strains from these two BU endemic areas revealed the presence of two phylogenetically distinct clonal complexes. The strains from the Nyong river basin were genetically more diverse and less closely related to the M. ulcerans strain circulating in Ghana and Benin than the strains causing BU in the Mapé river basin. Conclusions: Our comparative genomic analysis revealed that M. ulcerans clones diversify locally by the accumulation of SNPs. Case isolates coming from more recently emerging BU endemic areas, such as the Mapé river basin, may be less diverse than populations from longer standing disease foci, such as the Nyong river basin. Exchange of strains between distinct endemic areas seems to be rare and local clonal complexes can be easily distinguished by whole genome sequencing. Author Summary: Buruli ulcer (BU) is a progressively necrotizing disease of the skin, caused by infection with Mycobacterium ulcerans. BU occurs very focally with highest incidence in West Africa. The mode of transmission and the nature and role of potential environmental reservoirs are currently not entirely understood. In this study we sequenced whole genomes of sets of M. ulcerans case isolates from two BU endemic regions in Cameroon. We identified two distinct phylogenetic lineages, which directly correlated with the two endemic regions. Furthermore, we showed that the genetic diversity of M. ulcerans is higher in the older endemic region of Cameroon (Nyong river basin) compared to the more recently emerged infection focus in the same country (Mapé river basin). Together, our results demonstrate that M. ulcerans is developing local clonal complexes by the accumulation of single nucleotide polymorphisms (SNPs) and that these complexes often remain confined to individual endemic foci. The gene encoding for rpoB, which is known to harbour drug resistance mutations against rifampicin in M. tuberculosis, was not affected by SNPs in any of the analysed M. ulcerans strains. [ABSTRACT FROM AUTHOR]

A previous survey for clinical cases of Buruli ulcer (BU) in the Mapé Basin of Cameroon suggested that, compared to older age groups, very young children may be less exposed to Mycobacterium ulcerans. Here we determined serum IgG titres against the 18 kDa small heat shock protein (shsp) of M. ulcerans in 875 individuals living in the BU endemic river basins of the Mapé in Cameroon and the Densu in Ghana. While none of the sera collected from children below the age of four contained significant amounts of 18 kDa shsp specific antibodies, the majority of sera had high IgG titres against the Plasmodium falciparum merozoite surface protein 1 (MSP-1). These data suggest that exposure to M. ulcerans increases at an age which coincides with the children moving further away from their homes and having more intense environmental contact, including exposure to water bodies at the periphery of their villages. Author Summary: Although M. ulcerans, the causative agent of Buruli ulcer (BU), was identified in 1948, its transmission pathways and environmental reservoirs remain poorly understood. The occurrence of M. ulcerans infections in endemic countries in West and Central Africa is highly focal and associated with stagnant and slow flowing water bodies. BU is often described as a disease mainly affecting children <15 years of age. However, taking the population age distribution into account, our recent longitudinal survey for BU in the Mapé Dam Region of Cameroon revealed that clinical cases of BU among children <5 years are relatively rare. In accordance with these findings, data of the present sero-epidemiological study indicate that children <4 years old are less exposed to M. ulcerans than older children. Sero-conversion is associated with age, which may be due to age-related changes in behavioural factors, such as a wider movement radius of older children, including more frequent contact with water bodies at the periphery of their villages. [ABSTRACT FROM AUTHOR]

A previous survey for clinical cases of Buruli ulcer (BU) in the Mapé Basin of Cameroon suggested that, compared to older age groups, very young children may be less exposed to Mycobacterium ulcerans. Here we determined serum IgG titres against the 18 kDa small heat shock protein (shsp) of M. ulcerans in 875 individuals living in the BU endemic river basins of the Mapé in Cameroon and the Densu in Ghana. While none of the sera collected from children below the age of four contained significant amounts of 18 kDa shsp specific antibodies, the majority of sera had high IgG titres against the Plasmodium falciparum merozoite surface protein 1 (MSP-1). These data suggest that exposure to M. ulcerans increases at an age which coincides with the children moving further away from their homes and having more intense environmental contact, including exposure to water bodies at the periphery of their villages. [ABSTRACT FROM AUTHOR]

Buruli ulcer (BU), a neglected tropical disease of the skin and subcutaneous tissue, is caused by Mycobacterium ulcerans and is the third most common mycobacterial disease after tuberculosis and leprosy. While there is a strong association of the occurrence of the disease with stagnant or slow flowing water bodies, the exact mode of transmission of BU is not clear. M. ulcerans has emerged from the environmental fish pathogen M. marinum by acquisition of a virulence plasmid encoding the enzymes required for the production of the cytotoxic macrolide toxin mycolactone, which is a key factor in the pathogenesis of BU. Comparative genomic studies have further shown extensive pseudogene formation and downsizing of the M. ulcerans genome, indicative for an adaptation to a more stable ecological niche. This has raised the question whether this pathogen is still present in water-associated environmental reservoirs. Here we show persistence of M. ulcerans specific DNA sequences over a period of more than two years at a water contact location of BU patients in an endemic village of Cameroon. At defined positions in a shallow water hole used by the villagers for washing and bathing, detritus remained consistently positive for M. ulcerans DNA. The observed mean real-time PCR Ct difference of 1.45 between the insertion sequences IS2606 and IS2404 indicated that lineage 3 M. ulcerans, which cause human disease, persisted in this environment after successful treatment of all local patients. Underwater decaying organic matter may therefore represent a reservoir of M. ulcerans for direct infection of skin lesions or vector-associated transmission. Author Summary: Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans which affects mainly children in West Africa. Although it is commonly believed that the infection originates from an environmental source, both the reservoir of M. ulcerans and the mode of transmission to human patients remain to be elucidated. Previous investigations indicated that transmission likely takes place away from the homes of patients. We therefore screened the farms as well as village and farm water locations of 46 laboratory confirmed BU patients of the Mapé Basin of Cameroon for the presence of M. ulcerans DNA by real-time PCR. In this analysis three positive village water locations were identified. By studying one of these locations in great detail we found that M. ulcerans DNA persists in underwater detritus in one section of the village water location even after all local cases had been treated. The detritus may represent a reservoir of M. ulcerans from where infection could take place through either direct contamination of skin lesions or through contamination or colonization of insect vectors. [ABSTRACT FROM AUTHOR]

Ophiolites are the remnants of ancient oceanic crust that can serve as tools to reconstruct the evolutionary history of fossil oceans. At Boumnyebel, the western part of the Yaoundé group, the sole of the lower unit (magnesian mica-schists and gneiss) of the Pan-African nappes is made up of ophiolitic rocks (talc schists, chlorite schists, serpentinites, amphibolites, pyroxenites, hornblendites). Structurally, the lower unit has a flat-lying schistosity with some recumbent folds while the underlying TTG gneisses are marked by a high-dipping foliation at Mapan. The contact between the Pan-African mica schists and the basement formations (Congo craton) is therefore discordant. In ophiolitic rocks, amphibole is actinolite, tremolite or magnesio-riebeckite. Chlorite compositions correspond to clinochlore. Talc shows notable substitution of Mg by Fe whereas substitution of Mg by Fe and Al prevails in serpentine. Spinel compositions are either Cr-rich with high FeO/Fe 2 O 3 values (peridotitic spinels) or Cr-poor with low FeO/Fe 2 O 3 values (melt-derived or magmatic spinels). Main mineral features indicate a metamorphic retromorphosis of the original lherzolites, harzburgites, dunites and pyroxenites to hornblendites and serpentinites. This is followed by hydrothermal alteration (at various temperatures: 250–570 °C and low pressure: < 2 kbar) that yielded chlorite schists and talc schists. Chemically, talc schists are made up of SiO 2 , MgO and minor FeO and Al 2 O 3 , while chlorite schists and hornblendites contain notable amounts of Al 2 O 3 and CaO, respectively. All the ultramafic rocks display the same range of high Ni, Cr, Co contents with various LREE enrichments but flat HREE patterns. Multi-element patterns show that most talc schist are depleted in almost all elements. All the ultramafic rocks are marked by deep Nb, Ta, K, Pb, Sr, Ti, Zr and Hf troughs suggesting that the ultramafic rocks possibly derived from heterogeneous mantle sources varying from fertile to refractory peridotites. Amphibolites are generated from N-MORB, IAT or CA geotectonic settings. The compositions of spinel and ultramafic whole rocks reveal an arc setting that has evolved from divergent plate setting (oceanisation, N-MORB) to convergent plate (IAT, CA, SSZ D-MORB) settings. In summary, ophiolites emplaced in various geotectonic settings and were amalgamated during the Pan-African collision. • Ophiolitic rocks of Mapan area in the Yaoundé group, Cameroon. • Petrology and geochemistry of talc-schists and related rocks. • Hydrothermal P-T conditions. • Geotectonic settings. • Pan-African orogeny in Cameroon. [ABSTRACT FROM AUTHOR]

Buruli ulcer (BU), a neglected tropical disease of the skin, caused by Mycobacterium ulcerans, occurs most frequently in children in West Africa. Risk factors for BU include proximity to slow flowing water, poor wound care and not wearing protective clothing. Man-made alterations of the environment have been suggested to lead to increased BU incidence. M. ulcerans DNA has been detected in the environment, water bugs and recently also in mosquitoes. Despite these findings, the mode of transmission of BU remains poorly understood and both transmission by insects or direct inoculation from contaminated environment have been suggested. Here, we investigated the BU epidemiology in the Mapé basin of Cameroon where the damming of the Mapé River since 1988 is believed to have increased the incidence of BU. Through a house-by-house survey in spring 2010, which also examined the local population for leprosy and yaws, and continued surveillance thereafter, we identified, till June 2012, altogether 88 RT-PCR positive cases of BU. We found that the age adjusted cumulative incidence of BU was highest in young teenagers and in individuals above the age of 50 and that very young children (<5) were underrepresented among cases. BU lesions clustered around the ankles and at the back of the elbows. This pattern neither matches any of the published mosquito biting site patterns, nor the published distribution of small skin injuries in children, where lesions on the knees are much more frequent. The option of multiple modes of transmission should thus be considered. Analyzing the geographic distribution of cases in the Mapé Dam area revealed a closer association with the Mbam River than with the artificial lake. Author Summary: Buruli ulcer (BU) is an infectious disease caused by Mycobacterium ulcerans that is affecting mostly children in endemic areas of West Africa. Proximity to slow flowing water is a risk factor, but the exact mode of transmission of BU remains unclear. Man-made environmental changes, such as sand mining, damming of rivers and irrigation have been implicated with increases in disease incidence. Here, we report findings from a survey for BU and continued case detection thereafter in the Bankim Health District of Cameroon. In this area, the local population believed that the damming of the Mapé River has led to the emergence of BU. In 28 months we identified 88 laboratory confirmed cases of BU. Studying these cases, we found that the age adjusted cumulative incidence of BU in the elderly is similar to that in children and that the distribution pattern of BU lesions neither matches mosquito biting patterns nor the distribution of small skin injuries. Multiple modes of transmission should therefore be considered. Our data further showed that the patients appear to have closer contact to the local Mbam River than to the artificial Mapé dam reservoir. [ABSTRACT FROM AUTHOR]

New and published geochemical, petrologic, and geo-thermobarometric data of meta-basites were combined to constrain the geodynamic evolution of the Paleoproterozoic Nyong complex (NyC) in southwestern Cameroon, a part of the Central African tectonic belt. Their geochemical signatures, including (La/Yb) N = 0.53–56.26, slightly positive Eu anomalies (0.21–1.04), abundance of Pb and U, negative Nb–Ta anomalies, and REE depletion, suggest various degrees of partial melting of mostly spinel-bearing mantle sources. In addition, the meta-basite protoliths can be classified as IAB-, E-MORB-, N-MORB-, and exceptionally OIB-compositional types with minor crustal contamination. Petrologically, the meta-basites are characterized by coronitic textures, marked by microblasts and porphyroblasts of garnet surrounded by plagioclase or by both plagioclase and clinopyroxene, indicating metamorphic recrystallization under decompression. Our new geo-thermobarometric data outline various segments of an overall clockwise pressure‒temperature path. In the different meta-basite samples, the pressure peak at eclogite-facies conditions (∼625 °C, 11.7 kbar) was followed by nearly isobaric heating to amphibolite-facies conditions (600–690 °C, 11.5 kbar) or decompression and heating to amphibolite- (∼740 °C, 10.8 kbar) and granulite-facies (∼800 °C, 10.0 kbar) conditions. The retrograde path evolved from granulite- (850–750 °C, 11.3–7.6 kbar) and amphibolite- (790–550 °C; 12.4–3.0 kbar) to epidote-amphibolite- (∼600‒490 °C, 8.0–7.6 kbar) and greenschist-facies (∼400 °C, 4.2 kbar) conditions. Combining the new with published, in general high to middle temperature-middle pressure data from various rock types, with published high temperature-high pressure data from eclogites highlights distinct burial-exhumation paths for the NyC rocks: these paths document a clockwise pressure-temperature evolution, typical for a collisional setting associated with the Rhyacian-Orosirian Eburnean/Trans-Amazonian orogeny in Cameroon. The eclogite data outline a deep burial–isothermal decompression evolution, typical for a subduction setting predating the collisional setting. [Display omitted] • Nyong complex contains the suture zone between the Congo and the São Francisco cratons. • Paleoproterozoic Nyong complex provides a record of the Eburnean orogeny. • Nyong meta-basite protoliths derived from various IAB, E-MORB, N-MORB and OIB sources. • Nyong meta-basites were overprinted in subduction and continental collision settings. • Nyong meta-basites experienced clock-wise eclogite-, granulite-to amphibolite- and greenschist facies metamorphism. [ABSTRACT FROM AUTHOR]

The antimicrobial activities of 10 plant species (Voacanga africana, Crepis cameroonica, Plagiostyles africana, Crotalaria retusa, Mammea africana, Lophira lanceolata, Ochna afzelii, Ouratea elongata, Ou. flava and Ou. sulcata), each of which is currently used in the traditional medicine of Cameroon, were investigated in vitro. The activities of a methanol extract of each plant were tested, in disc-diffusion assays, against 37 reference or laboratory strains of seven species of microorganism (Staphylococcus aureus, S. epidermidis, Enterococcus hirae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans). The minimal inhibitory concentrations of each extract were then estimated, against each of the more susceptible microorganisms (i.e. those giving an inhibition zone measuring at least 9 mm in diameter in the disc-diffusion assays), by agar dilution. Although, in the disc-diffusion assays, each of the 10 methanol extracts investigated displayed some degree of antimicrobial activity against at least one species of microorganism, no activity against the Gram-negative bacteria (Es. coli, K. pneumoniae and Ps. aeruginosa) was observed. The extract with the greatest antimicrobial activity was that of Pl. africana (Euphorbiaceae). [ABSTRACT FROM AUTHOR]