Northern Cameroon Research Articles

Neuro-Architecture in Service of the Autism Spectrum: Designing a School Complex Adapted to Autistic Children in Northern Cameroon

This research explores the application of neuro-architecture in the design of a school complex adapted for autistic children in the northern region of Cameroon. The literature review highlights the specific characteristics of autism spectrum disorders (ASD) and the particular sensory needs of children with this condition in an educational setting. It analyzes how architecture, through the management of light, colors, materials, and spatial arrangement, can positively influence the well-being and learning of these children. By integrating the principles of neuro-architecture, the design of optimized school spaces can help reduce sensory overload and improve the social and educational inclusion of autistic children. This review also examines international case studies and potential adaptations to the geographic and cultural context of northern Cameroon, which is characterized by a lack of suitable educational infrastructure. The objective of this research is to propose architectural design solutions that meet the specific needs of autistic children while considering local constraints.

Evaluation of the insecticidal efficacy of four plants to protect stored Bambara groundnuts [Vigna subterranea (L.) Verdc. (Fabaceae)

Bambara groundnuts [Vigna subterranean] is one of the main legumes consumed in Northern Cameroon. However, stored nuts by farmers are quickly destroyed by pests leading to low yields. To overcome this constraint, the efficient control of stored grains from insect pests is dependent on synthetic insecticides. To reduce post-harvest losses of stored voandzou seeds, four botanicals insecticides have been developed and evaluated on the main pest. Plant powders prepared from Piper nigrum Linn. (Pipericaceae), Syzygium aromaticum (L.) Merr. & L.M.Perry (Myrtaceae), Xylopia aethiopica Dunal (Annonaceae) and Phaseolus vulgaris L.( Fabaceae), at different doses were tested on Callosobruchus maculatus Fabricius under laboratory conditions. The rest of the study involved combining black bean powder with the three condiment species in different proportions. The analysis shows a highly significant difference (p < 0.0001) between the mortality induced by formulations on day two of exposure with the lowest dose (0.5 g). These mortalities are 100%, 94.44 ± 3.79%, 72.5 ± 96 and 8.33 ± 4.77, respectively for S. aromaticum, P. nigrum, X. aethiopica and P. vulgaris powders. In relation to the formulation, the results show S. aromaticum powder induced 100% mortality compared with 94.44%, 72.59% and 8.33% respectively for P. nigrum, X. aethiopica and P. vulgaris plant powder at a dose of 5%. The results show that the natural substances used had a good insecticidal action against bruchid. The persistent compounds present in the studied spice plant powders are not toxic for human consumption at the concentrations used, but rather a beneficial effect. Key words: botanical insecticide, aromatic plants, powder, seeds, storage, insect pest.

Emergency Preparedness for Waterborne Diseases in the Wake of Floods in Northern Cameroon: A Call for Immediate Action

Severe flooding in Northern Regions of Cameroon (Far North, North and Adamawa Regions), triggered by torrential rains, has led to widespread displacement, destruction of infrastructure, and significant disruptions in essential services, particularly water, sanitation, and healthcare. This article, issued by public health researchers from Science For Life Foundation and Pinnacle University Institute, highlights the heightened risk of waterborne diseases following the recent floods and underscores the urgent need for enhanced emergency preparedness and response measures. Floods create conditions conducive to the spread of diseases such as cholera, typhoid fever, dysentery, and viral hepatitis by contaminating drinking water supplies with sewage and waste. Vulnerable populations, including children, pregnant women, the elderly, and those with pre-existing health conditions, are at increased risk. Overcrowding in temporary shelters further exacerbates the potential for disease outbreaks. The impact of climate change is intensifying the frequency and severity of such flooding events, making timely and effective intervention critical. This article reviews best practices for preventing and mitigating waterborne disease outbreaks, offering guidance to government authorities, health agencies, humanitarian organizations, and local communities. It aims to catalyze immediate action to safeguard public health and prevent a major crisis in the aftermath of the flooding Keywords: Waterborne Diseases, Flooding, Emergency Preparedness.

Study of knowledge, attitudes and practices of self-medication among pregnant women in the town of Mokolo in Northern Cameroon

Self-medication is a major public health problem worldwide, given the consequences it can have. However, its consequences seem to be poorly understood by the general public. The aim of this study was to investigate the knowledge, attitudes and practices of self-medication among pregnant women, by identifying the reasons for this practice, the most commonly consumed drugs and their origin. This was an analytical cross-sectional study using a structured questionnaire among women in the town of Mokolo in northern Cameroon. Data were collected and analyzed using SPSS 25. A total of 300 pregnant women were included in the study, 189 of whom were self-medicating, representing a prevalence of 63.00%. The reasons given by these women were: economic difficulties (55.56%), previous experience of treating a similar illness (20.11%), difficulties in accessing a healthcare professional (15.34%) and the feeling that the condition/illness was benign and therefore did not require a medical consultation (8.99%). The drugs most concerned were paracetamol (47.7%), amoxicillin (7.67%), diclofenac (5.67%) and aluminum hydroxide (5.67%). In addition to these pharmaceutical products, some pregnant women also used herbal preparations for treatment. Self-medication was highest in the first trimester of pregnancy (79.89%). Pregnant women who were most likely to self-medicate were those who were unaware of the dangers of self-medication and those with non-formal, primary education. Patient knowledge of self-medication during pregnancy was poor in 224 women (74.67%). More than three-quarters of patients (75.33%) had negative attitudes to self-medication during pregnancy. More than half (52.33%) had inadequate practices.

Assessment of land cover degradation due to mining activities using remote sensing and digital photogrammetry

Appropriate environment management requires an understanding of how mining activity alters environmental characteristics and how those changes affect an area. Therefore, to reduce the adverse effects of mining activity on the land, it becomes crucial to have relevant information about responses to environmental degradation. This study aims to assess the impact of semi-mechanised and artisanal mining activities on the land cover using remote sensing data and photogrammetric analysis, in the Mbale locality, Northern Cameroon. For this purpose, the maximum likelihood classification algorithm of the supervised classification method combined with field surveys was used to map environmental changes, based on Sentinel-2 images of 2019, 2021, and 2023. Normalized Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI), Brithness index (BI), and Soil crust index (SCI), were calculated to assess changes in vegetation, bare soil, water body, and exploited area. The orthophoto obtained from photogrammetric processing was performed to outline river network change through visual interpretation techniques and to calculate the volume of pits created by mining. The result of classified images indicated that vegetation cover decreased by 11.74% over the studied years. However, bare soil and exploited areas increased by 9.2% and 5.4% respectively. The calculated spectral indices show that between 2019 and 2023 the locality of Mbale considerably lost its vegetation cover, in favor of bare soil. The color of the soil and the granulometric size of the topsoil have also changed. The photogrammetry analysis highlighted the deviation of the main river and estimated the volume of pits created by mining activity to 22188.7 m3. The mining activities caused a loss of the vegetation cover, generated big pits, and multiple deviations of the Lom River from its natural course, which have a substantial negative influence on the ecosystem. Such data can be used for long-term environmental management, reclamation and rehabilitation monitoring, and mining area restoration.

Unveiling the traditional preparation, biochemical, phytochemical components, antioxidant and microbial properties of “jenja”, a ready-to-serve ginger-based beverage vended and consumed in northern Cameroon

“Jenja” is a refreshing yellow to brownish coloured beverage rudimentary made from ginger rhizomes. Given a paucity of data on the quality features of this spiced beverage, the current study was done to unveil its characteristics and safety status. A field survey was conducted with 35 producers and 70 consumers, followed by the collection of 10 samples from various locations for analysis. The surveys showed that traditional preparation of “jenja” incorporates simple unit operations. The spicy beverage had an acidic pH of 4.4 ± 0.9, with average reducing sugar, soluble protein, free amino acid and ash contents of 10.3 ± 2.3 mg/mL, 18.2 ± 9.9 mg/mL, 10.4 ± 3.8 mg/mL, 4.7 ± 2.6 %, respectively. The total phenolic content (TPC), total flavonoid content (TFC), and total condensed tannin content (TTC) were 44.0 ± 6.1 mgPGE/mL, 10.3 ± 2.5 mgQE/mL and 7.2 ± 5.7 mgCE/mL, respectively. The beverage demonstrated in-vitro DPPH and FRAP antioxidant activities with average values of 45.5 ± 5.3 and 68.3 ± 14.1 mgTE/mL, respectively. “Jenja” beverage had a poor microbiological quality and unsatisfactory safety status. Given all of the foregoing, “jenja” has the potential to be a powerful functional beverage if additional modifications are made to improve its preparation, microbiological profile and safety status.

Paleoenvironmental factors controlling organic-rich formations deposition in the Babouri-Figuil Basin (Northern Cameroon)

The Babouri-Figuil Basin is an intracratonic basin (half-graben) in northern Cameroon that is genetically connected to the Benue Trough from Nigeria, and is an area of interest in terms of petroleum prospectivity. Recent studies highlighted the presence of organic-rich formations in the basin. However, none of these works have identified factors that governed the accumulation of organic matter (OM) in the sediments. The main objective of this work is the characterization of these formations through palynofacies and organic geochemical techniques (total organic carbon - TOC, total sulfur, insoluble residue and biomarkers), in order to determine the organic facies, their depositional environments and the main drivers for organic enrichment in the basin. The current study reveals that black shale and massive claystone lithologies constitute the main organic-rich formations in the basin, with TOC reaching up to 26.08 wt%, being characterized by a dominance of bacterially-derived amorphous OM. Palynofacies and biomarker data revealed that these formations are positively associated with anoxic conditions and a partly highly saline and stratified lake water column. The deposition of organic-rich formations in the Babouri-Figuil Basin was mainly controlled by restriction conditions which developed in connection with the regional tectonic framework. The Lower Cretaceous rifting episode in the West and Central African Rift System (WCARS) basins led to the formation of accommodation space, a reduction in water levels, and the development of anoxic conditions within the basin, facilitating the deposition of organic-rich formations. Therefore, the organic enrichment of the Babouri-Figuil Basin has been predominantly controlled by its tectonic evolution, particularly during the syn-rift phase. This phase created favorable conditions for the deposition and preservation of OM, including the establishment of anoxic conditions. Additionally, the paleoclimate (arid conditions), the development of bacterial biomass, and the basin's paleogeography all played a significant role in this process. The organic-rich formations of the Babouri-Figuil Basin show characteristics of prospective petroleum source rocks (high organic content, high proportion of oil-prone kerogen, significant thickness and lateral extension). The combination of organic-rich formations with sandstone deposits above and extensive claystone/shale deposits on top can indicate the presence of an oil play in the basin. A detailed study with broader sampling is needed to investigate thoroughly the variation of organic facies and the influence of paleoenvironmental factors that control the deposition of thick source rock intervals.

Youth, Associational Life and Civic Engagement in Northern Cameroon: Association des Jeunes Élèves et Étudiants de la Faada

ABSTRACT This article analyses the ways in which youths in Northern Cameroon have been able to access social citizenship. Tracing the nature of this access over an extended period – from the early 1990s to the mid-2020s – I underline the importance of youth civic engagement through associational life. Associational life is a hidden or covert way of engaging in politics, and leads to a reinvention of their interaction with hegemonic power, as they are not positioning themselves as moral stakeholders in their community. Drawing on a case study involving the members of the Association des Jeunes Élèves et Étudiants de la Faada, with longitudinal ethnographic data combined with interviews, the article articulates changes and continuities in civic engagement, based on learning by doing through discursive practices (in street parliaments), physical practices (amateur football clubs) and associative practices (in non-profit associations).

The deformed alkaline Balda granite (Northern Cameroon): A witness of back-arc basin in the northern part of Central African Orogenic Belt

Located on the border between the NW Cameroon and Mayo-Kebbi domains in northern Cameroon, the Balda pluton is a deformed alkaline granite. Due to its unique location and geological features, it holds crucial information for understanding the evolution of the Central African Orogenic Belt (CAOB), which remains poorly understood. This multidisciplinary study combines field data, microscopic observations, Anisotropy of Magnetic Susceptibility (AMS), and U-Pb zircon dating to constrain the geodynamic evolution of the CAOB.The Balda pluton is a NNE-SSW elongated pluton consists mainly of aegirine-riebeckite granite and leucogranite. It displays diverse magnetic susceptibility values (Km) spanning from 0.19 x 10-3 to 21.98 x 10-3. Notably, 93 % of the Km values exceed 5 × 10-4SI, indicating a prevalence of mixed paramagnetic and ferromagnetic mineralogy (such as magnetite-rich). This observation is supported by microscopic examinations and K-T curves. An analysis of AMS unveils high P% values (2.8 to 58.7 %, with a mean of 15 %) and prevalent oblate magnetic fabrics (68 %). The magnetic foliation generally aligns with the field foliation and has steep dips ranging from NNE to NE or from SSW to SW and magnetic lineations exhibit shallow plunges (<35°) from SSW to SW. Microscopic analysis reveals high-temperature, solid-state deformation microstructures, indicating post-emplacement deformation processes and the presence of kinematic markers consistent with sinistral shear. Zircon grain analysis reveals two distinct types: “bright” and “dark.” These types differ in both their appearance under cathodoluminescence and their chemical composition. Bright zircons yield a U-Pb age of 732.7 ± 7.5 Ma, interpreted as the pluton emplacement age. Dark zircons are younger (ca. 680 Ma), suggesting a later tectono-metamorphic or alteration event.The integration of these results in a larger geodynamic context suggests that the Balda pluton formed within a syn-orogenic extensional back-arc basin. This emplacement was followed by significant post-emplacement deformation characterized by sinistral simple shear-dominated transpression likely related to the continental collision (ca. 680 Ma) of the NW Cameroon and Mayo-Kébbi domains.

Ethnopharmacological Investigation of Plants Used in the Treatment of Breast Cancer in Northern Cameroon

IntroductionTherapeutic activities of medicinal plants are due to the different secondary metabolites, which are stored in their organs and constitute a large reservoir. These medicinal plants could allow the development of new biomolecules, which would constitute an alternative against highly toxic breast cancer chemotherapy. The present study identifies the medicinal plants used by the traditional medicine practitioners of the northern region of Cameroon in the treatment of this pathology. MethodsA semistructured questionnaire was used to collect sociodemographic information from participants as well as ethnobotanical and ethnopharmacological data of the different treatments. The approach used to conduct the survey was an interview with the traditional medicine practitioners of the region using the local language. ResultsAs a result, 131 traditional healers were interviewed; they provided 50 therapeutic recipes made from 37 plant species belonging to 21 families. The recipes presented are mainly formulated from a single plant (74%) while among the combinations, associating two plants was predominant (18%). The bark was the most used organ (46%) while the most used preparation methods were decoction (52%) and maceration (36%). Treatments were mainly administered orally for an unlimited duration (until recovery). The plants listed were found to be rich in secondary metabolites such as alkaloids, flavonoids, or tannins that revealed anticancer activities through literature. ConclusionsThe results of the present work constitute a strong basis for the search of new anticancer chemotherapeutic agents that would be more available and less invasive.

Tectonic and sedimentary evolution of the Northern Cameroon Cretaceous rift basins: A study of the Babouri-Figuil and Mayo Oulo-Lere basins

The Babouri-Figuil and Mayo Oulo-Lere basins located in Northern Cameroon are small elongated sedimentary asymmetric half-grabens associated with the development of the West and Central African Rift System (WCARS). The evolution of these basins began during the Precambrian pre-rift period and continued through the Late Jurassic - Early Cretaceous periods, although details of their development remain unclear. The aim of this study is to understand the evolution and development of the border faults and their control on syn-rift geometry, accommodation space, and the resulting stratigraphic architecture. Using a combination of multiples surface and subsurface well logs data, we demonstrate the relationship and evolution of various stages of rifting and the associated sedimentary architecture. The basin is composed of an alluvial to lacustrine succession that developed during its tectonic evolution. A 3-stage tectonic model is proposed for the evolution of the basin that uses fault propagation analysis to describe the sedimentary architecture and evolution of basin geometry. The three stages of the model are the early rift, rift climax, and late rift; here, the early rifting phase is marked by the reactivation of faults in the Lower Cretaceous. The rift climax phase resulted in the interconnection of small segmented border faults leading to the high rate of activation of major border faults and to the development of the half graben structure of the basins. The late rift stage is marked by a decrease in border fault activity and accommodation. Sediment distribution and the facies architecture are controlled by tectonic subsidence created throughout the rifting phases. The stratigraphic signature of the Babouri-Figuil and Mayo Oulo-Lere basins are punctuated by the lacustrine water transgression-regression cycles, and controlled by the balance between the rate of sediment supply and tectonic accommodation. The progressive change between overfilled to starved sedimentary architecture is illustrated by this stratigraphic succession. Additional age assessment and sub-surface data in future work could help confirm the structures identified on the surface.

Morphological and microchemical signatures of alluvial gold and electrum grains from the Tcholliré gold district, northern Cameroon: Insights to potential epithermal gold system in the area

Morphological and microchemical signatures of alluvial gold and electrum grains from the Tcholliré gold district, northern Cameroon: Insights to potential epithermal gold system in the area

Impact of Plant Extracts on the Pollination Activity of &amp;lt;i&amp;gt;Apis mellifera&amp;lt;/i&amp;gt; Linnaeus, 1758 (Hymenoptera: Apidae) on Flowers of Cowpea Variety Feekem, in Dang (Adamaoua, Cameroon)

Synthetic pesticides present worldwide risks of contamination of humans, livestock and the environment due to the strong persistence and the toxic residues in fruits and vegetables. Natural biopesticides of local plant origin present low persistence and are the best alternative for the control of crop pests. In the Adamaoua region (Northern Cameroon), few studies exist concerning effects of botanical pesticides on the behavior of beneficial insects. Studies aimed to draw up a list of pollinating insects on flowers of &amp;lt;i&amp;gt;Vigna unguiculata &amp;lt;/i&amp;gt;(L.) Walp., 1843 (Fabales: Fabaceae), in situations of treatment with botanical pesticides compared to the situation of the use of synthetic insecticide and to determine the effect of the biopesticides on the behavior of the main floricultural insects. Field investigations were carried out during two cowpea cultivation campaigns (June to September 2021 and June to October 2022) in Dang (suburb of Ngaoundere) on the effect of leaves extracts of local plant origin on the foraging behavior of &amp;lt;i&amp;gt;Apis mellifera&amp;lt;/i&amp;gt; Linnaeus, 1758 (Hymenoptera: Apidae) and the main sap-sucking insect &amp;lt;i&amp;gt;Aphis craccivora &amp;lt;/i&amp;gt;Koch, 1854 (Hemiptera: Aphididae). Forty-four cowpea plots of 4x3.5 m each distributed according to the randomized complete block model (four untreated plots as negative control, four plots treated with the synthetic insecticide Parastar (40EC 535/ 10/IN, 20 g/l of imidacloprid and 20 g/l of lamda-cyhalothrin) as positive control, and 36 experimental plots treated with three concentrations (10%, 20% and 30%) of aqueous leaves extract of &amp;lt;i&amp;gt;Calotropis procera&amp;lt;/i&amp;gt; (Gentianales: Apocynaceae), &amp;lt;i&amp;gt;Eucalyptus camaldulensis &amp;lt;/i&amp;gt;(Myrtales: Myrtaceae), and &amp;lt;i&amp;gt;Tithonia diversifolia&amp;lt;/i&amp;gt; (Asterales: Asteraceae) respectively, made it possible to conduct four treatments: (1) flowers left to freely pollination, (2) flowers protected against pollinators, (3) flowers visited exclusively by &amp;lt;i&amp;gt;Ap. mellifera&amp;lt;/i&amp;gt; and (4) flowers protected against insects. Among eight species (four orders, four families and seven genera) recorded on the flowers of &amp;lt;i&amp;gt;V. unguiculata&amp;lt;/i&amp;gt;, the domestic bee &amp;lt;i&amp;gt;Ap. mellifera&amp;lt;/i&amp;gt; was the most common and collected nectar and pollen. The control plots and those treated with 10% or 20% aqueous leaves extracts allowed the bee to carry out its activity. Plots treated with 30% extract of each plant and those treated with the synthetic insecticide Parastar, drastically altered the rhythm and speed of activity in &amp;lt;i&amp;gt;Ap. mellifera&amp;lt;/i&amp;gt; foragers. This behavior became less coordinated and slow on treated plants. It would be wise to use 10% or 20% aqueous extracts as botanical insecticides and an alternative to the synthetic insecticide Parastar.

Distribution and ecological aspects of sand fly species from Kousseri, an endemic focus of visceral leishmaniasis in Northern Cameroon

IntroductionKousseri in the Far North Region of Cameroon has long been known as an endemic focus of visceral leishmaniasis (VL), although the study on sand flies in this focus is scarce. The present study investigates the spatial distribution, seasonality, and ecological aspects of sand flies from Kousseri. This study is based on the need to optimize the effectiveness of leishmaniasis control programs in the northern part of the country. MethodsSand flies were sampled monthly over 12 months in five selected sites using CDC light traps. Only captured females were morphologically identified at species level based on valid keys. Results and discussionOverall, 4,214 sand fly specimens were collected during 360 trapping nights. The male/female sex ratio slightly favored females (1:1.04). The eudominant Sergentomyia antennata followed by both dominant Sergentomyia schwetzi and Sergentomyia squamipleuris were the most common and abundant species, accounting for 76.1% of the collection. Phlebotomus duboscqi, the confirmed vector of cutaneous leishmaniasis (CL) in West African foci, although rare in the collection, was found in four of the five surveyed sites. This sand fly species with Se. schwetzi abounded in peri-urban areas and, respectively, in animal shed and in uninhabited house biotopes, while Se. antennata and Se. squamipleuris prevailed in rural areas and, respectively, in animal shelter biotopes and outside dwellings. All caught sand fly species except Se. schwetzi, Sergentomyia clydei, Sergentomyia inermis, and Sergentomyia adleri prevailed during the dry season. The highest Shannon–Wiener index of sand flies due to the maximal richness and evenness was found in the urban area, in outdoor biotopes, and during the rainy season (H′ = 1.68, 1.80, and 1.74, respectively). These data provide evidence that less urbanized areas, animal shelters around the compounds, and the absence of precipitation (dry season) favored the dispersion of abundant sand fly species in Kousseri. Based on previous reports on Leishmania transmission, a surveillance plan is required to prevent an outbreak of VL or an establishment of CL or canine leishmaniasis (CnL) in this focus. Further research identifying the blood meal source and the Leishmania parasites in these insects is critical for providing insightful data to fight leishmaniasis in Northern Cameroon.

The Effects of Mayors’ Human Capital on Investments in Northern Cameroonian Municipalities

The objective of this paper is to examine the effects of mayors’ human capital on the investments of northern Cameroonian municipalities. The human capital of mayors is operationalized in terms of the level of education (diploma), training, and age. The data in the study are from 46 councils in northern Cameroon, including 21 in the Adamawa region, 12 in the north, and 13 in the far north. After carrying out the preliminary statistical tests (multicollinearity and homoscedasticity) for the cross-sectional data, the result of OLS shows that the human capital of mayors has an effect on the investments of northern Cameroonian municipalities. Particularly, the level of education of mayor (as measured by the diploma) has positive effects on municipal investments. However, the coefficients of educational attainment and age of mayors are not significant. The result also shows that the coefficients of some control variables are statistically significant.

The internal transcribed spacer 1 sequence polymorphism brings updates to tsetse species distribution in the northern Cameroon: Importance in planning efficient vector control.

Vector control remains one of the best strategies to prevent the transmission of trypanosome infections in humans and livestock and, thus, a good way to achieve the elimination of human African trypanosomiasis and animal African trypanosomiasis. A key prerequisite for the success of any vector control strategy is the accurate identification and correct mapping of tsetse species. In this work, we updated the tsetse fly species identification and distribution in many geographical areas in Cameroon. Tsetse flies were captured from six localities in Cameroon, and their species were morphologically identified. Thereafter, DNA was extracted from legs of each tsetse fly and the length polymorphism of internal transcribed spacer-1 (ITS1) region of each fly was investigated using PCR. ITS1 DNA fragments of each tsetse species were sequenced. The sequences obtained were analysed and compared to those available in GenBank. This enabled to confirm/infirm results of the morphologic identification and then, to establish the phylogenetic relationships between tsetse species. Morphologic features allowed to clearly distinguish all the tsetse species captured in the South Region of Cameroon, that is, Glossina palpalis palpalis, G. pallicera, G. caliginea and G. nigrofusca. In the northern area, G. morsitans submorsitans could also be distinguished from G. palpalis palpalis, G. tachinoides and G. fuscipes, but these three later could not be distinguished with routine morphological characters. The ITS1 length polymorphism was high among most of the studied species and allowed to identify the following similar species with a single PCR, that is, G. palpalis palpalis with 241 or 242 bp and G. tachinoides with 221 or 222 bp, G. fuscipes with 236 or 237 bp. We also updated the old distribution of tsetse species in the areas assessed, highlighting the presence of G. palpalis palpalis instead of G. fuscipes in Mbakaou, or in sympatry with G. morsitans submorsitans in Dodeo (northern Cameroon). This study confirms the presence of G. palpalis palpalis in the Adamawa Region of Cameroon. It highlights the limits of using morphological criteria to differentiate some tsetse species. Molecular tools based on the polymorphism of ITS1 of tsetse flies can differentiate tsetse species through a simple PCR before downstream analyses or vector control planning.

Novel insights about petroleum systems from source and reservoir rock characterization, Cretaceous Deposits, Babouri-Figuil Basin, Northern Cameroon

The Babouri-Figuil Basin (BFB) is a frontier basin for petroleum in Cameroon. It belongs to the series of Cretaceous rift basins of the West and Central Rift System (WCARS), the origin of which is related to the opening of the South Atlantic. Within the same rift system, commercial hydrocarbon accumulations have been discovered in Chad, Sudan, Niger and, more recently, in Nigeria (Gongola Basin). The study of the geology of the BFB just recently received considerable attention, mainly because of its presumed hydrocarbon potential. In the pursuit of researching possible petroleum systems in the BFB, the current study provides a first look into the characterization of source and reservoir rock and its integration into a 2D lithostratigraphic model. The study was solely based on outcrop samples. Black shale and massive claystone are good to excellent hydrocarbon source rocks [e.g., up to 38 wt% total organic carbon (TOC), up to 943 mg/g hydrogen index, up to 85 m thickness, up to 20–30 km lateral extension], with moderate to high values of extractable organic matter (e.g., >10,000 ppm). Calcareous claystone, on the other hand, are poor source rocks [e.g., <0.20 wt% TOC]. The samples are thermally immature, except for those located close to volcanic intrusion at Golombe that have reached the threshold for oil generation (Tmax >435 °C, production index >0.1). The petrographic analysis of sandstone revealed that they are fine-grained to coarse-grained, poorly to moderately sorted, texturally and compositionally immature to submature, subarkosic to arkosic arenites. The main diagenetic processes that affected sandstones are as follows: moderate to intense compaction characterized by the development of long, concavo-convex, and sutured contacts between grains; cementation through calcite, iron oxide, and quartz cements; alteration of mica and feldspar grains; partial to complete dissolution of feldspar, mica, amphibole grains, and calcite cement; and the replacement of feldspar and mica grains by clay minerals. Alteration and dissolution increase the porosity of sandstone through the creation of secondary pores. However, mechanical compaction through the development of a pseudomatrix and cementation as pore-filling materials have significantly reduced the quality of sandstone beds as conventional petroleum reservoirs. Hence, the best reservoir-quality sandstones in the basin are generally located in the upper portion of the basin in terms of its lithostratigraphic model. They are the cleanest sandstones with the smallest amount of cement and the lowest ductile grain content (pseudomatrix), with a thickness that varies from 3 m to 120 m and a lateral extension of 20 km. The lithostratigraphic model of the basin is characterized by an extensive lacustrine environment that provided a thick sequence of organic-rich formations; sand deposited as extensive reservoirs sandwiched between shale/claystone beds; the development of stratigraphic traps through lateral facies change; and the widespread deposition of lacustrine and floodplain claystone that provide regional seals. The similarities between the Babouri-Figuil Basin and proven petroleum systems in other WCARS rift basins suggest that the basin may host at least one petroleum system where actively generating source rocks are present.

Supergene gold transformations of the placer gold deposits from the Gamba district in northern Cameroon: Implications for secondary and nano-particulate gold formations

The northern part of Cameroon is a Sudanese or Sudano-Sahelian type characterized mainly by a dry climate, a significant landscape position, and distance from the primary gold (Au) sources, giving the occasion to explore the study of complex supergene Au transformations. This study on the biogeochemical transformation of Au in Cameroon will expand understanding of this process and provide advantageous results for Au recovery from materials that are ultimately regarded as waste. In this study, placer Au particles were collected from four individual sites, Djaba, Bigbal, Bougma, and Mayo Salah, and analyzed using a scanning electron microscope (SEM), electron probe microanalysis (EPMA) and LA-ICP-MS Time of Flight (ToF) to observe nanometer-sized Au grain morphologies, the Au mobility and spatial association between Au and related major and minor elements by element distributions in Au particles, respectively. The results from the examination of Au samples across all sampling sites show that Au particles are formed by the binary Au/Ag alloys and that the formation of Au nano- and micro-particles is associated with Au/Ag dissolution and Au re-precipitation. The abundant nano- and micro-particles of Au morphotypes within the cavities of primary Au grains across all the sampling locations were associated with the polymorphic layers formed by clays, iron-oxides, and silicate minerals. The nano- and micro-particles of Au overgrow as colloids and crystalline phases of triangular, spherical, hexagonal, and octahedral platelet aggregates of bacteriomorphic Au and were indicative of biogeochemical transformation. The high Au concentrations in the rim suggest the dissolution of Ag and Cu involving Au mobility identified in placer Au grains across the individual sites. Hence, the minor elements, such as Ag and Cu, occur in solid solution in the Au cores, while trace elements, such as Si, Al, Fe, Cr, Ti, Ga, Ni, Pb, Mn, V, and As, form impurities or micro inclusions in the rim of native gold which was interpreted as evidence of Au mobility. Furthermore, the Au grains are commonly associated with pyrite, chalcopyrite, bornite, and galena. This can only be attributed to the hypogene orogenic precipitation environment, implying that Au grains were transported from primary sources. Overall, the Au particle transformation and mobility of placer Au highlighted in this study was a good indicator for understanding biogeochemical mechanisms affecting gold particles in the northern Cameroon supergene environments.

Exploring the molecular mechanisms of increased intensity of pyrethroid resistance in Central African population of a major malaria vector Anopheles coluzzii.

Molecular mechanisms driving the escalation of pyrethroid resistance in the major malaria mosquitoes of Central Africa remain largely uncharacterized, hindering effective management strategies. Here, resistance intensity and the molecular mechanisms driving it were investigated in a population of Anopheles coluzzii from northern Cameroon. High levels of pyrethroid and organochloride resistance were observed in An. coluzzii population, with no mortality for 1× permethrin; only 11% and 33% mortalities for 5× and 10× permethrin diagnostic concentrations, and <2% mortalities for deltamethrin and DDT, respectively. Moderate bendiocarb resistance (88% mortality) and full susceptibility to malathion were observed. Synergist bioassays with piperonyl butoxide recovered permethrin susceptibility, with mortalities increasing to 53.39%, and 87.30% for 5× and 10× permethrin, respectively, implicating P450 monooxygenases. Synergist bioassays with diethyl maleate (DEM) recovered permethrin and DDT susceptibilities (mortalities increasing to 34.75% and 14.88%, respectively), implicating glutathione S-transferases. RNA-seq-based genome-wide transcriptional analyses supported by quantitative PCR identified glutathione S-transferase, GSTe2 (RNA-seqFC = 2.93 and qRT-PCRFC = 8.4, p < 0.0043) and CYP450, CYP6Z2 (RNA-seqFC = 2.39 and qRT-PCRFC = 11.7, p < 0.0177) as the most overexpressed detoxification genes in the pyrethroid-resistant mosquitoes, compared to mosquitoes of the susceptible Ngousso colony. Other overexpressed genes include P450s, CYP6M2 (FC = 1.68, p < 0.0114), CYP4G16 (FC = 2.02, p < 0.0005), and CYP4G17 (FC = 1.86, p < 0.0276). While high frequency of the 1014F kdr mutation (50%) and low frequencies of 1014S (6.61%) and 1575Y (10.29%) were observed, no ace-1 mutation was detected in bendiocarb-resistant populations, suggesting the preeminent role of metabolic mechanism. Overexpression of metabolic resistance genes (including GSTe2 and CYP6Z2 known to confer resistance to multiple insecticides) in An. coluzzii from the Sudan Savannah of Cameroon highlights the need for alternative management strategies to reduce malaria burden in northern Cameroon.

In Vitro Filaricidal Properties of Aqueous Extracts of Combretum nigricans (Combretaceae) on Onchocerca ochengi (Onchocercidae).

Onchocerciasis is an endemic parasitic disease in sub-Saharan Africa that significantly impacts animal and human health. In Northern Cameroon, medicinal plants from the Combretum genus are used for onchocerciasis traditional treatment although there is no scientific evidence of their antifilarial potential. This study evaluates the in vitro macro- and microfilaricidal properties of water extracts from Combretum nigricans in Onchocerca ochengi. Material and Methods. O. ochengi microfilariae and adult male worms were recovered from cowhide fragments. Oxidative stress indicators and motility tests were used to assess the filaricidal impact. Female albino rats were used to test for acute toxicity. The contents of secondary metabolites were quantified. The bark aqueous extract was more active on macrofilariae at 1 mg/mL for 24 h (100%) than the leaf (63.9%) and root (75%) extracts at the same concentration. Likewise, a stronger microfilaricidal effect was found with this extract at 0.5 mg/mL for 1 h (100%) compared to root and leaf extracts. The dose-response effect with the bark extract gave an inhibitory concentration 50 (IC50) of 351 μg/mL vs. 113 μg/mL for flubendazole after 24 h incubation, while the microfilaricidal efficacy revealed an IC50 of 158.7 μg/mL vs. 54.09 μg/mL for ivermectin after one-hour incubation. Examining stress indicators on parasite homogenates showed that macrofilaricidal activity is associated with a significant increase in nitric oxide, glutathione, and malondialdehyde generation and a decrease in catalase activity. At 2000 mg/kg, rats showed no harm. The phytochemical investigation revealed that the barks contained more phenolic acids, condensed tannins, flavonoids, and saponins than the leaves (p < 0.001). These findings support C. nigricans' antifilarial activity and identify oxidative stress indicators as prospective treatment targets in O. ochengi. It would be interesting to conduct in vivo studies to understand their antifilarial activity better.