Search Results (337)

Groundwater is one of the basic requirements for life, economic and social developments in the Bazo River catchment, Rift Valley, Southern Ethiopia. In the study area, availability of water is faced with several problems, such as quality issues due to high levels of fluoride in some samples, spring scarcity in the lowlands, unprotected river water used for drinking, and high demand for good quality water. The aim of this study was to investigate the hydrogeochemical characteristics and to evaluate groundwater quality for domestic and irrigation uses. Thirty-four primary groundwater samples were collected from the field and analyzed in the water quality lab of Arba Minch University. Two water quality indices (WQI and EWQI), a variety of irrigation water quality indices, and GIS-based spatial analysis were utilized in this study. Cations were present in the descending order of Na > Ca > Mg > K > Fe, and anions were HCO₃⁻ > Cl > SO₄ > NO₃⁻ > F. Excepting two samples (BH8 and SP3), the water samples were acceptable for drinking. Sodium, TDS, and fluoride levels were over the limit of drinking water in BH8 and SP3. Rock–water interaction, cation exchange, and silicate mineral weathering were the main hydrogeochemical reactions that controlled groundwater composition in the area, based on Gibb’s diagram, chloro-alkaline indices, and major ions ratios. Groundwater facies were identified as Ca.HCO₃, Na.HCO₃ and mixed Ca-Na/Ca.Mg.Na.HCO₃ types using a Piper plot. The water quality index was computed, and its spatial variations were mapped using GIS. About 82.35% of groundwater samples were excellent for drinking use and 94.12% (SAR) of groundwater were acceptable for irrigation. These study results are useful to help develop inclusive strategies and interventions to address groundwater quality aspects in the study area, underlining the significance of managing and monitoring water resources. The findings underscore the need for effective management and monitoring strategies to ensure sustainable groundwater resources in the Bazo River catchment. Full article

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that causes severe illness in livestock and humans, with significant economic and health repercussions. Mauritania is considered an RVF focus in West Africa. A cross-sectional survey was conducted in 2023 in 12 of Mauritania’s 15 provinces. Serum samples from 849 small ruminants (428 goats and 421 sheep) were analyzed by ELISA for IgG and IgM antibodies against RVF virus. Logistic regression analyses were performed to assess associations between seropositivity and species, age, sex, season, and geographic location. In total, 14.1% of the animals tested were positive for anti-RVFV IgG antibodies. There was no association between anti-RVFV IgG positivity and the ruminant species, the sex, the age and the season. Hodh El Gharbi had the highest seroprevalence (40.5%), followed by Adrar (19.8%) and Tagant (19.7%). The lowest levels were recorded in Tiris Zemmour (2%) and Inchiri (3%). Only two animals tested positive for IgM, suggesting limited recent viral activity. This nationwide survey confirms widespread exposure of small ruminants to RVFV in Mauritania. Strengthening longitudinal serological monitoring and integrating ecological and entomological data within the “One Health” approach will be essential to preventing future epidemics and protecting animal and human health. Full article

Background/Objectives: Emerging viral zoonoses represent a growing threat to global public health, with most newly emerging infectious diseases originating from animal reservoirs. Recent outbreaks of monkeypox, Ebola virus disease, Marburg virus disease, Rift Valley fever, and avian influenza highlight the capacity of zoonotic viruses to cross species barriers, spread internationally, and generate substantial health, social, and economic consequences. This review examines the ecological, epidemiological, and biological determinants of viral zoonotic emergence and transmission, with particular emphasis on vaccination and outbreak prevention strategies. Methods: A structured narrative review was conducted using a predefined literature search strategy across major scientific databases. Peer-reviewed epidemiological, clinical, and public health publications published between January 2000 and February 2026 were screened and selected according to predefined relevance criteria. Results: The emergence of viral zoonoses is driven by complex interactions among animal reservoirs, environmental and climatic changes, human behavior, and viral adaptation. Although transmission pathways and clinical outcomes differ among pathogens, common determinants of spillover and outbreak amplification were identified. Current evidence supports the importance of integrated surveillance, genomic monitoring, vaccination strategies, and community engagement as key components of preparedness and response. Emerging preventive approaches targeting pathogen transmission, including transmission-blocking strategies and vector-associated microbiota interventions, may provide additional opportunities for disease control. Conclusions: Strengthening preparedness for emerging viral zoonoses requires coordinated One Health approaches integrating human, animal, and environmental health. Future priorities include the development of next-generation vaccines, expansion of digital and genomic surveillance systems, improved equitable access to vaccines, and innovative interventions aimed at reducing zoonotic spillover and interrupting pathogen transmission. Full article

Rift Valley fever virus (RVFV) and Crimean–Congo hemorrhagic fever virus (CCHFV) are endemic zoonotic pathogens in Senegal, transmitted by mosquitoes and ticks, respectively. Understanding the seasonal and spatial dynamics of their vectors is essential to improve targeted surveillance. This study investigated the abundance, diversity, and viral infection status of vector populations in a transboundary region (Matam) and a non-transboundary region (Thiès) over two seasons from September 2022 to March 2024. We collected mosquitoes using CO₂-baited CDC light traps and sampled ticks directly from domestic small ruminants. A total of 6558 mosquitoes across 23 species and 1904 ticks representing seven species were morphologically identified. Mosquito abundance peaked significantly during the rainy season. Conversely, tick diversity increased during the dry season, with Hyalomma rufipes emerging as the predominant species. Crucially, RVFV was detected exclusively in Aedes vexans mosquito pools from the transboundary Matam region, emphasizing the epidemiological risk associated with cross-border livestock mobility. Viral RNA of CCHFV was detected in multiple tick species across both regions and seasons, confirming a sustained, multi-vector enzootic cycle. These findings demonstrate persistent RVFV and CCHFV circulation in Senegal and highlight the critical need for integrated, season-specific vector surveillance frameworks. Full article

Background: Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic pathogen that has caused repeated epidemics across Africa and the Arabian Peninsula, posing a severe and growing threat to public health and livestock. Infection in ruminants causes high neonatal mortality and catastrophic abortion storms; human disease ranges from self-limiting febrile illness to hemorrhagic fever, encephalitis, and permanent blindness. No licensed human vaccines or specific antiviral therapeutics are available, creating an urgent unmet medical need. Methods: We systematically reviewed the peer-reviewed literature on RVFV neutralizing antibodies (NAbs), extracting and synthesizing data on antibody sources, epitope specificity, in vitro neutralizing potency, in vivo protective efficacy, and molecular mechanisms of action. Results: A growing body of work has identified potent NAbs from immunized rodents, rabbits, alpacas, non-human primates, and convalescent patients. These NAbs predominantly target the Gn and Gc envelope glycoproteins. Their mechanisms include blocking host receptor (LRP1) binding, preventing the pH-dependent conformational rearrangement of the Gn–Gc complex, and directly inhibiting viral membrane fusion. Lead candidates, such as RVFV-268 and RVFV-140, achieve sub-nanogram neutralization and confer robust protection in rodent models against lethal challenge, aerosol exposure, and vertical transmission. Bispecific antibodies and combination strategies further enhance potency and the genetic barrier to viral escape. Conclusions: Substantial progress has illuminated the epitope landscape and neutralization mechanisms of RVFV, yielding promising clinical candidates. Translational challenges remain, including viral immune escape, antibody thermostability, and the need for rigorous preclinical evaluation. Future efforts should prioritize structure-guided engineering, rational antibody combinations, and testing in clinically predictive animal models. Full article

The Central Rift Valley (CRV) of Ethiopia is an ecologically and socioeconomically important region increasingly threatened by environmental degradation driven by unsustainable land and water use, population growth, and climate variability. This review synthesizes existing literature to provide an integrated assessment of hydrological, ecological, and social dimensions in the CRV. The study draws on published data and reports to evaluate water resource depletion, pollution, biodiversity loss, wetland degradation, land use change, and their impacts on livelihoods and habitability. Results indicate that lakes and groundwater resources are under severe stress from agricultural intensification, industrial expansion, and urbanization, leading to declining water availability and deteriorating quality. Land cover change, wetland loss, and deforestation have reduced ecosystem resilience and accelerated biodiversity decline. Governance frameworks remain fragmented and often fail to address the complex interactions between hydrology, ecology, and human activities. The review concludes that adopting a Critical Zone Science (CZS) perspective offers a comprehensive framework for linking land, water, ecological, and social processes, and that integrated land and water management, ecosystem restoration, and climate-resilient strategies are essential to improve sustainability and community well-being. Full article

Rift Valley fever (RVF) is a viral zoonosis endemic in Madagascar, threatening human and animal health as well as the economy. Trade-related livestock movements are a major factor in the spread of RVF virus. While previous RVF research in Madagascar has focused on farmers or general ecology, this study is the first to specifically target livestock traders, the primary drivers for long-distance viral spread, in the Alaotra Mangoro endemic hotspot. This study aimed to assess the level of knowledge, prevailing attitudes and current practices regarding RVF among people engaged in livestock trade in the Alaotra Mangoro region, as well as the factors associated with these KAPs. A descriptive and analytical cross-sectional survey was conducted among 406 livestock traders in five districts of the Alaotra Mangoro region, using a structured questionnaire. A multi-stage sampling approach was employed, utilising purposive selection of markets followed by snowball sampling to reach informal traders often missed by traditional surveys. Generalised linear mixed models were used to analyse factors associated with KAPs regarding RVF. Awareness of RVF was very low (only 18.5% respondents had heard of it), with significant regional disparities (0% in Anosibe An’Ala versus 51.6% in Moramanga). Veterinarians (15.5%), family (12.8%), radio (9.6%) and neighbours (9.6%) were the main sources of information. Understanding of symptoms and modes of transmission (particularly mosquito bites) was limited. Higher levels of education (OR = 181.6; 95% CI: 29.9–1123.7; p < 0.001) and older age (50–60 years) were associated with better knowledge. Proactive attitudes were scarce (21.4%), although more than half (53.4%) believed that RVF is a real disease. Perception of personal risk and the contribution of livestock trade to the spread of the disease was low. However, confidence in animal vaccination was relatively high (60.3%). Preventive practices were highly inadequate. The majority did not wear protective equipment when handling sick animals (94.6%) and rarely avoided touching aborted foetuses (12.6%). Less than half (48.3%) expressed a willingness to report sick or dead animals, and nearly half admitted to having sold or purchased sick livestock (49.5%). Cooking meat (95.1%) and using mosquito nets (74.1%) were the only well-established practices. More than half of respondents (57.9%) lived more than 5 km from veterinary services, and cost was the most frequently cited barrier to consultation. Participation in awareness campaigns was virtually non-existent (5.4%). Results revealed critical gaps in KAP that may contribute to the persistence of RVF. A “One Health” approach is imperative, integrating human, animal and environmental health. Full article

Mafic ultrapotassic volcanics (kamafugites, mafurites) are the youngest eruptives in the Bunyaruguru volcanic field, which is part of the Toro Ankole Province at the northernmost reach of the West Branch of the East African Rift Valley. We obtained new data using LA-ICP-MS on the trace element contents (rare earth, large ion lithophile, high field strength and compatible elements) in clinopyroxene phenocrysts from mafurite lava of the Bunyaruguru volcanic field. The clinopyroxenes are notable for their anomalously high zirconium contents (up to 800–1000 ppm), which is unusual in mafic silicate magmas but typical for clinopyroxenes from carbonatite lavas. This distinctive signature is not found in clinopyroxene in coeval mafic lavas from neighboring vents. Carbonate is also found in the Bunyaruguru volcanic rocks in the form of inclusions in high-Mg olivine phenocrysts, suggesting carbonated material exists in the source of kamafugite magmas. Carbonatites are widespread in the neighboring Fort Portal volcanic field, and we interpret the high-zirconium clinopyroxene as evidence for mixing of mafurite magmas with carbonatite melts. Full article

Background: Malaria remains hyperendemic in the Democratic Republic of the Congo, while arboviral infections are increasingly reported but remain under-surveilled, particularly in remote regions. Overlapping ecological niches and non-specific clinical presentations complicate case management and surveillance. Methods: A cross-sectional door-to-door survey was conducted in December 2023 in Inkanamongo village (Lokolia Health Area, Boende Health Zone, Tshuapa Province). Blood samples were collected from 379 adults; malaria infection was assessed by using HRP2-based rapid diagnostic tests, and arboviral IgG antibodies were measured on dried blood spots using Luminex^® multiplex immunoassay. Sociodemographic data were collected via standardized questionnaires. Results: Malaria prevalence was 51.7% (95%CI: 46.7–56.7). Overall arboviral seroprevalence reached 78.4% (95%CI: 73.1–81.5), dominated by O’nyong-nyong virus, 42.8% (95%CI: 37.6–47.5), Rift Valley fever virus, 32.0% (95%CI: 26.9–36.2), and chikungunya virus, 23.4% (95%CI: 19.0–27.4). Concurrent malaria infection and arboviral exposure were observed in 40.4% (95%CI: 35.6–45.4) of participants. No sociodemographic factors were significantly associated with co-exposure in the multivariable analysis. Conclusions: Substantial co-exposure of malaria and multiple arboviruses occurs in this remote Congo Basin setting. Integrated surveillance and improved diagnostics are urgently needed to guide febrile illness management and preparedness in under-resourced regions. Full article

In 2024 Kenya had a population of 4.78 million camels that contributed to the livelihoods of pastoralist communities in northern Kenya. Previous studies in Kenya, Saudi Arabia and eastern Africa demonstrated high seroprevalence of Middle East respiratory syndrome coronavirus (MERS-CoV)-specific antibodies in dromedary camels, as well as sporadic transmission of MERS-CoV from camels to humans. Based on the MERS-CoV data and the very close contact between owners and their camels in northern Kenya, we speculated that camels may also transmit other zoonotic viruses, such as Rift Valley fever virus (RVFV). In this study, 493 camel and 197 human sera were collected in Marsabit, Kenya, through a cross-sectional survey in 2018 and analyzed for the presence of RVFV IgG antibodies using a laboratory-developed indirect enzyme-linked immunosorbent assay (ELISA). Overall, 15.6% of camels and 7.6% of humans were RVFV IgG-positive; IgG-positive camels were predominantly females in large population herds and IgG-positive humans were engaged in farming-related activities and were greater than 18 years old. Of the eight location groups sampled, two had high camel (site 2 and site 6) and two had high human (site 5 and site 6) RVFV seropositivity rates. These data suggest that camelids, such as dromedary camels, may serve as amplifying hosts for vector-borne zoonotic diseases, such as RVFV, and that humans with frequent farming and camel meat, milk, or camel product contact may have increased risk for RVFV exposure or infection. Full article

This study of the Ethiopian Rift Valley meso-climate (5° N–9° N, 37° E–40° E) employed space–time statistical methods over the period 1981–2025. Links between weather conditions at Hawassa (7.1° N, 38.5° E, 1700 m) and the Indian Ocean Dipole (IOD) were uncovered, among 3–4 yr oscillations and a weak upward trend. Seasonal anomalies of local dewpoint temperature (Td) and IOD cross-correlated at R = 0.61 over the four-decade study. Mean annual cycling revealed a narrow range for Td from April to October, in contrast with bi-modal rainfall and asymmetric runoff. Diurnal cycle analysis indicated that evening rainfall was driven by midday heat (0.6 mm/h) and moisture fluxes (0.1 mm/h). A case study revealed how shallow cloud bands extend westward from cool, forested highlands to the warm Rift Valley. Composite differences between warm and cool IOD events exhibited contrasting effects for zonal and meridional airflows, which explains why the equatorial trough and its associated rainfall are confined to the southeastern escarpment of Ethiopia. While earlier studies had anticipated drying trends, wetter conditions during the warm IOD events of 2019 and 2023 resulted in rising lake levels (1.8 m) and crop yields (4 T/ha). These findings enhance our understanding of regional climate dynamics to support adaptive management. Full article

Rift Valley fever virus (RVFV) and Crimean-Congo hemorrhagic fever virus (CCHFV) are designated by the World Health Organization as priority pathogens due to their epidemic potential, zoonotic transmission, and the absence of licensed therapeutics or vaccines. The development of effective antivirals critically relies on robust in vitro and in vivo models; however, progress is limited by the requirement for high-containment facilities. In this review, we provide a comprehensive overview of the experimental models currently available for RVFV and CCHFV, ranging from cell-based assays to animal models, and discuss their respective advantages, limitations, and translational relevance. We further highlight strategies allowing for BSL-2 experimentations, thereby expanding research accessibility, and accelerating the development of countermeasures against these high-priority pathogens. Full article

The constituent elements of source-to-sink systems and their coupling relationships are key controls on the development of sedimentary systems and the spatial distribution of sand bodies. Taking the Paleogene strata in the southern Laizhouwan Sag of the Bohai Bay Basin as a case study, we integrate drilling, logging, core, thin-section, and high-resolution 3D seismic data to quantitatively characterize basement lithology and effective provenance area, drainage-unit subdivision, types and scales of sediment transport pathways, and geometric parameters of depositional fans, within a source-to-sink analytical framework. The results show that: (1) Two distinct provenance types are developed in the southern Laizhouwan Sag, including Proterozoic granitic–gneissic basement and Mesozoic volcanic–clastic basement. These provenance types exhibit pronounced differences in effective source area, vertical relief, and drainage-network configuration across different sequence stages. (2) Two main categories of sediment transport pathways are identified, namely paleo-valleys and fault-controlled troughs. V-shaped, U-shaped, and W-shaped paleo-valleys show systematic morphological transitions along topographic gradients. The width-to-depth ratio of transport channels exerts a significant control on depositional fan scale, with U-shaped valleys exhibiting the highest sediment transport efficiency. Finally, (3) the depositional domain is dominated by near-source fan-delta systems, whose scale shows a strong positive correlation with effective provenance area and transport-channel morphology. Overall, the southern Laizhouwan Sag is characterized by a typical fault-controlled, steep-slope source-to-sink system, in which sedimentary system distribution is jointly governed by effective provenance area, sediment transport pathway geometry, and fault-related slope-break zones. This study provides a quantitative example and methodological reference for source-to-sink system characterization and prediction of favorable sand body distribution in continental rift basins. Full article

Rift Valley fever virus (RVFV) is a re-emerging, vector-borne pathogen endemic to Africa and the Arabian Peninsula, posing an increasing threat to human and animal health. Outbreaks have severe economic and social impacts on farmers, communities, and governments. Current diagnostic methods rely on PCR and ELISA; however, rapid pen-side tests would enable faster, cost-effective monitoring and outbreak control. Here, a species- and immunoglobulin class-independent capillary flow immunodiagnostic assay (lateral flow test; LFT) for detecting RVFV-specific antibodies is described. The assay uses a double-antigen approach, coupling the RVFV nucleocapsid protein, a major viral antigen, both to carbon nanoparticles and to a nitrocellulose membrane. The method was qualified with immune sera from sheep, calves, goats, and humans and benchmarked against a newly developed double-antigen ELISA and a commercial competition ELISA. Both the LFT and double-antigen ELISA demonstrated high specificity and sensitivity. This advancement brings RVFV-specific pen-side testing significantly closer to practical implementation. Full article

Background: Rift Valley fever virus (RVFV) is a significant mosquito-borne zoonotic virus with high public health and veterinary importance in Africa and the Middle East. Reliable diagnostic assays for detecting antibodies and assessing their functional neutralizing capacity are essential for surveillance programs, vaccine monitoring, and outbreak preparedness. Objective: This study evaluates and compares the analytical performance of a competitive enzyme-linked immunosorbent assay (cELISA) and a virus neutralization test (VNT) for detecting RVFV antibodies in vaccinated sheep sera, establishing an integrated laboratory workflow for virus titration, serological detection, and functional neutralization. Methods: Twenty serum samples were collected from sheep pre-vaccination and one month post-vaccination with Smithburn live attenuated RVFV vaccine. Sera were tested using a commercial multispecies RVFV competitive ELISA to detect antibodies specific to the viral nucleocapsid protein. Viral titration was conducted in Vero cells, and 50% tissue culture infective dose (TCID₅₀/0.1 mL) was calculated using the Reed and Muench method. VNT was performed at 24, 48, 72, and 96 h after infection with different viral doses (10² to 10⁵ TCID₅₀/0.1 mL), and the neutralizing ability of serial serum dilutions (1:2 to 1:1024) was tested. Compared with the control, protection was determined by cytopathic effect (CPE) inhibition. Results: ELISA revealed robust antibody signals up to a 1:32 dilution, with signal-to-noise (S/N) < 40%, whereas for higher dilutions, antibody detection became inconclusive or negative. Virus titration was performed to verify a stock concentration of 10^6.5 TCID₅₀/0.1 mL. The VNT exhibited time- and dose-dependent kinetics; high protection rates (≥97) were observed at 1:2–1:8 dilutions against 10²–10³ TCID₅₀/0.1 mL challenge doses; however, neutralizing efficacy decreased significantly at higher viral loads and higher serum dilutions. While cELISA and VNT results correlated strongly at low serum dilutions, the cELISA showed decreased sensitivity at dilutions ≥ 1:64, where the VNT remained capable of detecting functional neutralizing activity. Conclusions/Discussion: The results demonstrate that while both assays correlate well at high antibody concentrations, they diverge at lower concentrations. This discrepancy highlights the functional difference between binding antibodies (N-protein) and neutralizing antibodies (Gn/Gc glycoproteins). Consequently, the cELISA is ideal for rapid screening, whereas the VNT is indispensable for confirming functional immunity. Integrating both assays provides a more accurate immunological profile for RVFV surveillance and vaccine evaluation. Full article