Frédéric Nico Njayou

Hepatitis E virus (HEV) is a major zoonotic pathogen, and pigs are an important reservoir. Serology for anti-HEV antibodies poorly reflects active infection, while reverse transcription polymerase chain reaction (RT-PCR) is sensitive but not always feasible for large-scale surveillance. This study aimed to develop an immunoglobulin Y (IgY)-based sandwich enzyme-linked immunosorbent assay (ELISA) for direct detection of HEV antigen (HEV-Ag). An antigenic epitope from the HEV open reading frame 2 capsid protein was identified in silico, synthesized, and used to immunize laying hens; IgY was purified from egg yolk and characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. An in-house sandwich ELISA was subsequently developed using the anti-HEV IgY antibodies. Its diagnostic performance was evaluated against RT-PCR using 350 field-collected pig serum samples and compared with commercial anti-HEV IgG and IgM ELISA kits. Immunization yielded high-purity IgY antibodies, with antigen-specific antibody kinetics showing a significant increase in specific immunoreactivity from week 4 onward and peak sensitivity at weeks 6–8 post-immunization. The anti-HEV IgY showed high specificity, with no cross-reactivity observed against a heterologous antigen (HBsAg). The optimized sandwich ELISA detected HEV-Ag with a sensitivity of 95.4% and a specificity of 100% relative to RT-PCR. The prevalence of HEV-Ag was 17.7% (62/350), which was not significantly different from RT-PCR (18.6%, 65/350; p=0.250). In contrast, commercial IgG and IgM ELISAs showed high seroprevalence rates (34.9% and 28.3%, respectively) but exhibited significant discrepancies with RT-PCR (p<0.0001), indicating limited utility for identifying active infection. Overall, the developed IgY-based sandwich ELISA demonstrated high diagnostic performance for detecting active HEV infection. This assay represents a viable alternative to RT-PCR for large-scale surveillance, particularly in resource-constrained settings, and may contribute to improved control of zoonotic HEV transmission.

Cigarette smoking in developing countries like Cameroon is increasing with unspecified exposure levels to cadmium, a known toxic chemical. This study conducted in Buea (Southwest Region, Cameroon) aimed to estimate the risk exposure to cadmium inhalation from smoking and its association with the abnormal level of liver and kidney function biomarkers in apparently healthy smokers. A survey recruited smokers to collect data on smoking habits. Cadmium contents in the major cigarette brands selected served to estimate the cadmium Daily Exposure (DE), Weekly Inhalational Exposure (WIE) and the percentage contribution to the Tolerable Weekly Intake (TWI) of cadmium. Serum alanine aminotransferase (ALT) activity, urea, creatinine contents, and urinary albuminuria and glucosuria were measured in blood and urine samples from active and nonsmokers. The 102 smokers enrolled were categorized respectively as light (37.3%; 38/102), moderate (38.2%; 39/102), and heavy (24.5%; 25/102) smokers, smoking an average number of 4.7 ± 0.5, 9.1 ± 1.5, and 19.1 ± 3.0 cigarettes/day, respectively. Cadmium levels in cigarette brands ranged from 0.72-1.08 µg Cd per gram of tobacco removed from the cigarette. Heavy smokers exceeded the permitted cadmium No Significant Risk Level (NSRL) by up to 28-fold, contributing 4-8% to the cadmium TWI. Serum ALT activity and creatinine content were significantly higher ( P P <0.05) of displaying abnormal elevated serum urea content, positive albuminuria and glucosuria. Our findings demonstrated that healthy active smokers are highly exposed to cadmium inhalation and are at higher risk of displaying abnormally increased levels of biochemical markers of liver and kidney functions, indicating risks of organ damage.

Urease is an enzyme that plays a significant role in the pathogenesis of Helicobacter pylori responsible for numerous health issues, among which chronic gastritis, peptic ulcer disease, gastric neoplasia and even stomach cancer. Therefore, targeting urease represents a key strategy to attenuate gastritis induced by H. pylori. Khaya grandifoliola (KG) and Entada africana (EA) were prepared using methylene chloride/methanol (1:1, v/v). After that, the extracts were fractionated using a gradient of solvent and the anti-urease activities of crude extracts and fractions was evaluated. Mechanism of inhibition of urease by the most active fractions was determined using kinetic method. Polyphenols and flavonoids contents were determined. Extracts and fractions of KG and EA exhibited a significant inhibition of urease activity. The half inhibitory concentration (IC50) of KG (31.61 ± 0.23 µg/mL) and EA (35.70 ± 0.14 µg/mL) showed no significantly difference (P > 0.05) to the reference Thiourea (30.37 ± 0.30 µg/mL). In addition, the kinetic study revealed that the methanolic fraction (FMeOH) of KG and EA strongly inhibited the activity of urease with IC50 values of 31.60 ± 1.25 and 29.00 ± 1.05 µg/mL respectively. These fractions exhibited mixed-type inhibition with Kic and Kia values of 9.96 and 91.15 µg/mL for KG and 13.24 and 226.59 µg/mL for EA respectively. Both extracts contain phenolic compounds. Overall, this study indicated a high anti-urease activity of the methanolic fraction of KG and EA. Each fraction exerts a mixed inhibition on urease activity.

Malaria and typhoid fever remain major health issues in developing countries like Cameroon, with frequent co-infections. The potential liver damage caused by their respective causative pathogens is overlooked in health management, posing a significant risk of severe liver injury and worsening patient conditions. Accordingly, this study investigated the risk factors associated with liver damage in febrile patients with malaria, typhoid fever, or co-infection at the Obili District Medical Center and Mvog-Betsi Dominican Hospital Center, Yaoundé, Cameroon. Over 8 months, 350 febrile patients were evaluated for their adherence to preventive measures concerning malaria and typhoid fever using a structured questionnaire. Blood samples were analyzed for Plasmodium species and Salmonella antibodies and liver enzyme levels were measured. Liver damage was assessed using the Roussel Uclaf Causality Assessment Method. Risk factors for infections and liver damage were identified using Fisher’s Exact and Chi-Square tests, with significance set at P < 0.05. Among participants tested, 129 (36.86%) and 106 (30.29%) were positive for malaria and typhoid, respectively, while 56 (16.00%) were co-infected. Men (49.2% and 37.3%) were more affected than women (30.6% and 26.7%) for both malaria and typhoid, respectively. Participants aged between 20 and 40 years were the most affected by malaria (21.4%) and typhoid fever (17.4%). The non-use of mosquito nets, presence of standing water, bushes, and garbage dumps near residences were significant risk factors (Relative risk: RR > 2.1; P < 0.0001) for contracting malaria or typhoid fever. The co-infection status (Chi-2 = 18.30; P < 0.0001), parasite density (Chi-2 = 9.8; P = 0.0074), and delay before consulting (Chi-2 = 13.23; P = 0.0013) were significant risk factors for the occurrence of liver injuries. Our findings demonstrated that the alteration of liver enzyme activity, reflecting liver damage among patients with malaria, typhoid, or malaria-typhoid co-infection, is a reality and should be considered during the patient treatment.

The development of multifunctional drugs from anti-inflammatory agents is a promising strategy for people with several inflammation-related comorbidities since such medicines could reduce complications, improve health outcomes and lower healthcare costs. In this study, esters of ibuprofen, cinnamic and salicylic acids were synthesized and characterized by spectroscopic methods, with six new compounds identified. Cytotoxicity and anti-inflammatory properties were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay in mouse-derived peritoneal macrophages, which were obtained following an intraperitoneal injection of 0.5 ml of a 2% starch solution. All the tested compounds were safe up to 50% concentrations (2.41 × 10⁻⁴ to 2.41 mM), and monoethylene glycol di-ibuprofen ( 2 ) displayed the highest toxicity (IC ₅₀ = 4.90 mM). Most compounds were non-toxic below 2.41 mM, and all inhibited nitric oxide (NO) production in a concentration-dependent manner at 0.24 mM. Ibuprofen and cinnamic acid derivatives ( 2 , 3 , 5a and 14 ) exhibited enhanced anti-inflammatory effects, with IC ₅₀ = 0.002 mM for monoethylene glycol mono-ibuprofen ( 3 ), while fatty-acid ester salicylates ( DEW4 ) demonstrated weaker NO inhibition. Antioxidant tests (2,2-diphenyl-1-picrylhydrazyl, ferric reducing ability of plasma and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS)) showed limited activities, with few compounds reducing the ABTS+ radical (0.1 ˂ SC ₅₀ ˂ 0.2 mM). Compounds 3 , 5a , 7 , 12 and 14 are potential new anti-inflammatory drugs, while 2 may have anti-cancer properties.

Malaria and typhoid fever remain major health issues in developing countries like Cameroon, with frequent co-infections. The potential liver damage caused by their respective causative pathogens is overlooked in health management, posing a significant risk of severe liver injury and worsening patient conditions. Accordingly, this study investigated the risk factors associated to liver damage in febrile patients with malaria, typhoid fever, or co-infection at the Obili District Medical Center and Mvog-Betsi Dominican Hospital Center, Yaoundé, Cameroon. During 8 months, 350 febrile patients were evaluated for their adherence to preventive measures concerning malaria and typhoid fever using a structured questionnaire. Blood samples were analyzed for Plasmodium species and Salmonella antibodies and liver enzyme levels were measured. Liver damage was assessed employing the Roussel Uclaf Causality Assessment Method. Risk factors for infections and liver damage were identified using Fisher’s Exact and Chi-Square tests, with significance set at P2.1; P<0.0001) for contracting malaria or typhoid fever. The co-infection status (Chi-2 = 18.30; P<0.0001), parasite density (Chi-2 = 9.8; P=0.0074), and delay before consulting (Chi-2 = 13.23; P=0.0013) were significant risk factors for the occurrence of liver injuries. Our findings demonstrated that the alteration of liver enzyme activities, reflecting liver damages among patients with malaria, typhoid, or malaria-typhoid co-infection, is a reality and should be considered during the patient’s treatment.