Journal of Tropical Medicine最新文献

Silymarin is a polyphenolic flavonoid extracted from milk thistle. It has potent immunomodulatory effects and can inhibit the replication of influenza A virus (IAV). The present study aimed to determine the inflammatory and anti-inflammatory cytokine secretion patterns in mice before and after silibinin treatment. For this, bronchoalveolar lavage (BAL) fluids were collected from the thoracic cavity 5 days after the intervention, and viral quantification was performed using TaqMan Real-time PCR. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate IFN-γ and IL-10 levels in serum and BAL samples. Finally, pathological damage to lung tissue was assessed by pathologists. The results reveal that silibinin pretreatment exhibits a dose-dependent immunomodulatory effect on IFN-γ and IL-10 levels. After the virus challenge, silibinin reduced immune cell infiltration in mouse BAL fluid. These data similarly suggest a remarkable immunomodulatory effect of silibinin. Silibinin also decreased lung damage following the virus challenge in the post-treatment group, but its lung protective properties seem to be due to a different mechanism than when it was administered before infection. Finally, high doses of silibinin (post-treatment) significantly reduced viral load in BAL fluid compared to the virus challenge group. These results support the idea that therapies aimed at moderating immune and inflammatory responses are essential to decrease the mortality rate caused by IAV infection. Silibinin has strong immunomodulatory properties, can inhibit IAV infection, and reduces lung tissue damage in a dose-dependent manner.

Glycosaminoglycan (GAG) molecules on the surface of red blood cells play an important regulatory role in the invasion of merozoites of apicomplexan protozoa. Heparan sulfate, a type of GAG molecule, has been identified as an important receptor facilitating the invasion of red blood cells by these parasites. Proteins in the parasite that exhibit strong affinity for heparin may play a pivotal role in this invasion process. This study aims to use proteomics to identify Babesia microti proteins with high binding affinity to heparin. Bioinformatics was utilized to analyze the subcellular localization and biological functions of these proteins. Candidate genes encoding proteins with strong heparin affinity will be expressed in a prokaryotic system to produce recombinant proteins. The interaction between these recombinant proteins and heparin will be characterized through heparin-binding experiments and other methods. Initially, a mouse model of B. microti was established and high-density B. microti were obtained. Heparin affinity chromatography was then used to purify natural B. microti proteins that can bind to heparin, identifying 186 B. microti proteins via ESI-MS that specifically interact with heparin. Further studies were carried out to analyze those specific proteins with unique peptide segments of two or more, yielding 15 B. microti proteins, most of which are cell surface proteins and secretory proteins. Based on mass spectrometry identification and subsequent analyses, BMSA5-1-1, B. microti peptidyl-prolyl cis-trans isomerase (BmPPIase), and chaperonin were selected for further study due to their potential impact on the invasion of red blood cells by B. microti. These candidate proteins were expressed as recombinant proteins using a prokaryotic expression system. In vitro heparin-binding assays demonstrated that these recombinant proteins specifically bind to heparin. Notably, BmPPIase and chaperonin recombinant proteins exhibited activity in specific heparin binding. Molecular interaction studies further confirmed the strong interaction between BmPPIase and heparin. In conclusion, this study used proteomic methods to identify 186 specific B. microti proteins with specific binding affinity to heparin, providing in-depth analysis of 15 key proteins. The findings confirmed that BmPPIase and chaperonin specifically bind to heparin, with molecular interaction experiments substantiating the strong interaction between BmPPIase and heparin.

The loa22 protein is highly conserved among pathogenic Leptospira serovars and it is expressed during both acute and chronic infections. The aim of this study was to clone and sequence of the loa22 protein-encoding gene of Leptospira serovars. In this study, 23 pathogenic Leptospira serovars and two nonpathogenic Leptospira serovars were used. These serovars were obtained from the microbial culture collection of Leptospira Reference Laboratory, Department of Microbiology, Razi Vaccine and Serum Research Institute, Karaj, Iran. Three serovars, including L. Sejroe Hardjo-bovis, L. Grippotyphosa, L. Canicola, are used in the preparation of the trivalent vaccine. The loa22 gene was amplified by specific primers and the PCR products were then purified using kit and were cloned into a pTZ57R/T vector and transformed in competent E. coli DH5α cells. The cells were then plated onto LB agar containing ampicillin and recombinant colonies subjected to colony PCR to confirm the presence of the Leptospiral gene. Positive colonies plasmid vector was isolated from cells by High Pure Plasmid Isolation Kit. The loa22 gene was detected in all 23 pathogenic serovars, while this gene was not observed in nonpathogenic L. biflexa. It was determined that the similarity percentage of the sequenced pathogenic serovars is between 95.5% and 100%. The results concluded that the loa22 gene was highly conserved among various pathogenic Leptospira serovars and can be used to develop an effective recombinant vaccine.

Background: Dengue virus infection is a major source of morbidity and mortality in the majority of tropical and subtropical nations. In Nepal, the first case of dengue was reported in 2004, followed by numerous outbreaks exerting a critical impact on public health. This study aims to describe the clinical and laboratory characteristics of dengue patients visiting a tertiary care hospital to see the trend of presentation. Method: Hospital based cross-sectional study was conducted among diagnosed cases of dengue from April 2023 to September 2023. A total of 692 patients undergoing testing by commercially available dengue rapid diagnostic tests were recruited and categorized dengue positive (if NS1 and/or IgM positive) and dengue negative (NS1, IgM, and IgG all negative or only IgG positive). The dengue-positive cases were further subdivided into three groups (only NS1 positive, only IgM positive, both NS1 and IgM positive). Additionally, biochemical and hematological analyses were performed, and results were compared between positive and negative cases by using Mann-Whitney U test while subgroups of dengue-positive cases were compared using Kruskal-Wallis H test. Results: Most common symptoms were fever (94.5%) followed by headache (79.8%) and myalgia (74.7%). Among 346 dengue-positive subjects, 53.2% (n = 184) were NS1-only positive, 21.7% (n = 75) were IgM-only positive, and 25.1% (n = 87) were both NS1+IgM positive. Thrombocytopenia (n = 179, 51.7%), leucopenia (n = 99, 28.6%), increased SGPT (n = 182, 52.6%), increased SGOT (n = 188, 54.3%) were seen among dengue positive patients. Leukopenia was more severe in patients with only NS1 positive cases (p = 0.008) whereas thrombocytopenia (p ≤ 0.001) was more severe in patients with both IgM and NS1 positive cases. Conclusion: Our study depicted there is a marked alteration in biochemical and hematological parameters specifically thrombocytopenia, leukopenia, increased transaminase levels, and high prothrombin time seen in dengue positive cases.

Background: A diverse range of pollutants, including heavy metals, agrochemicals, pharmaceutical residues, illicit drugs, personal care products, and other anthropogenic contaminants, pose a significant threat to aquatic ecosystems. The Winam Gulf of Lake Victoria, heavily impacted by surrounding human activities, faces potential contamination from these pollutants. However, studies exploring the presence of antibiotic resistance genes (ARGs) in the lake remain limited. In the current study, a shotgun metagenomics approach was employed to identify ARGs and related pathways. Genomic DNA was extracted from water and sediment samples and sequenced using the high-throughput Illumina NovaSeq platform. Additionally, phenotypic antibiotic resistance was assessed using the disk diffusion method with commonly used antibiotics. Results: The analysis of metagenomes sequences from the Gulf ecosystem and Comprehensive Antibiotic Resistance Database (CARD) revealed worrying levels of ARGs in the lake. The study reported nine ARGs from the 37 high-risk resistant gene families previously documented by the World Health Organization (WHO). Proteobacteria had the highest relative abundance of antibiotic resistance (53%), Bacteriodes (4%), Verrucomicrobia (2%), Planctomycetes Chloroflexi, Firmicutes (2%), and other unclassified bacteria (39%). Genes that target protection, replacement, change, and antibiotic-resistant efflux were listed in order of dominance. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed antibiotic resistance to beta-lactamase and vancomycin. Phenotypic resistance to vancomycin, tetracycline, sulfamethoxazole, erythromycin, trimethoprim, tetracycline, and penicillin was reported through the zone of inhibition. Conclusions: This study highlights that the Winam Gulf of Lake Victoria in Kenya harbors a diverse array of antibiotic-resistant genes, including those conferring multidrug resistance. These findings suggest that the Gulf could be serving as a reservoir for more antibiotic-resistant genes, posing potential risks to both human health and aquatic biodiversity. The insights gained from this research can guide policy development for managing antibiotic resistance in Kenya.

Malaria remains a significant global health challenge, with the deadliest infections caused by Plasmodium falciparum. In light of the escalating drug resistance and the limited effectiveness of available vaccines, innovative treatment approaches are urgently needed. This study explores the potential of the probiotic Limosilactobacillus fermentum YZ01, isolated from traditionally fermented kindirmo milk, to modify host responses to Plasmodium berghei ANKA infection. Twenty-five male BALB/c mice were grouped and administered various treatments, including probiotic-enriched yogurt alone or in combination with antibiotics. Parameters assessed included gut lactic acid bacteria (LAB) composition, parasitaemia progression, survival rates, and immune response dynamics over a 21-day postinfection period. The probiotic treatment significantly altered gut microbiota, evidenced by increased LAB counts and modulated immune responses, notably enhancing IgM and IL-4 production while reducing IFN-γ levels. Mice receiving prolonged probiotic treatment exhibited delayed parasitaemia onset, reduced mortality rates, and a more robust immune response compared to control groups. These outcomes suggest that probiotic intervention not only tempers the pathological effects of malaria but also enhances host resilience against infection. This study underscores the role of gut microbiota in infectious disease pathogenesis and supports probiotics as a promising adjunct therapy for malaria management.

Enteric fever is a significant health problem in developing countries caused by Salmonella enterica serovars Typhi and Paratyphi. Unfortunately, the burden of the disease remains high not only because of the complications related to the disease but also, especially, because of the spread of the strains of Salmonella resistant to antibiotics. The aim of the present study was to evaluate the antibiotic resistance patterns of Salmonella Typhi and Paratyphi clinical isolates as well as the risk factors associated with infection. This cross-sectional study was conducted from June 2020 to September 2021. One thousand and seventy-six patients in the age range (1- ≥ 50 years) were recruited including 423 (39.31%) infected with S. Typhi, 115 (10.68%) infected with S. Paratyphi, and 538 (50%) noninfected after obtaining their informed consent using a face-to-face interview and questionnaire. The stool samples were collected in clean and sterile boxes reserved for this purpose and were cultured. Demographic parameters such as sex, age, occupation, water source, level of education, as well as clinical signs and symptoms were obtained. The resistance profile determination was carried out by the disk diffusion method. A multivariate logistic regression analysis was performed to identify factors associated with infection. Results of multivariate logistic regression analysis showed positive and significant associations (OR > 1; p < 0.05) between enteric fever and women among the age groups: 1-10 years, 11-20 years, and 21-30 years. These positive associations were also noted in patients who ate shellfish, salads, fruits, and vegetables; in patients who consumed ice cubes; as well as those who consumed food and drinks offered by ambulant merchants. This indicated that they are more likely to be infected by S. enterica than others. The level of multidrug-resistant (MDR) S. enterica to first-line antimicrobial agents ampicillin, chloramphenicol, and co-trimoxazole was high and selectively distributed according to age groups, marital status, profession, level of education, source of water, and lifestyle. The results highlighted the emergence of MDR S. enterica isolated in the study population, demonstrating resistance to first-line drugs, fluoroquinolones, and third-generation cephalosporins. Further studies with large-scale samples are needed to validate the present results and to monitor MDR S. Typhi and S. Paratyphi serovars in other parts of Cameroon.

Snakebites are a significant health issue, especially in tropical and subtropical regions. Envenomation from snakebites is a clinical emergency requiring prompt treatment. Recently, a new species of blunt-nosed viper, Macrovipera razii, was identified in central and southern Iran through morphological and molecular studies. This large, dangerous viper can deliver substantial amounts of venom. Following reports to the Faculty of Health at Shiraz University of Medical Science (SUMS), the identification of venomous snakes involved in envenomation cases in Fars province was undertaken. Approximately 20 snakes were captured and presented by locals, while others provided photos. Despite some information being photo-based, the data highlighted the significant role of this viper in envenomation cases. Macrovipera razii is now recorded from 12 counties in Fars province. One incident involved a male bitten in Shiraz, and another case led to a male needing limb amputation. This study emphasizes the importance of this newly described viper in recent snakebite envenomations in the region and reviews its distribution within the Fars province.

Background: Visceral leishmaniasis (VL) is one of the public health issues in some areas of Ethiopia, and over 3.2 million people are at risk with an estimated 4000 new cases occurring each year in the country. This study was conducted to determine the prevalence of VL and its associated risk factors in Addis Zemen Health Center, Northwest Ethiopia. Methods: Data were collected from Addis Zemen Health Center and meteorological office in Addis Ababa from 2012 to 2016. Univariate and multivariate analyses were conducted to identify the determinants of VL. According to the result obtained from the retrospective data analysis, a total of 4100 suspected VL patients diagnosed by rk39 in Addis Zemen Health Center from Libokemkem and nearby districts. Results: The overall prevalence of VL among study participants were 30% (1230/4100). Of this, the prevalence of VL among male and female study participants was 86.8% and 13.2%, respectively. The proportion of sex infected by VL was 3.26 times higher in male than female (AOR = 3.26, 95% CI: 2.42-4.40). The risk of acquiring VL in those people living in rural area was 62% more likely than those residing in urban (AOR = 1.62, 95% CI: 1.29-2.04). People that were traveled to the endemic area of VL were 18.44 times more likely to be affected than the people who have not traveled once (AOR = : 18.44, 95% CI: 14.49-23.47). Age, sex, residence, season, travel history to endemic areas, and mean monthly precipitation were found to be statistically significant for VL at 5% significance level. Conclusion and Recommendation: The prevalence of VL in the present study was high with the highest prevalence in the rural areas. Therefore, there is a need of the immediate establishment of sound control and prevention program in rural areas.

Malaria remains a critical global health issue, particularly in tropical and subtropical regions. The disease, caused by Plasmodium parasites, is transmitted by Anopheles mosquitoes and can lead to severe complications and death if untreated. The emergence of drug-resistant strains highlights the urgent need for new antimalarial agents. Gnetum gnemon, a plant native to Southeast Asia, has shown promise due to its rich bioactive compounds. This study aims to evaluate the suppressive, curative, and prophylactic antimalarial potential of Gnetum gnemon leaf extract (GGE) against Plasmodium berghei in mice. GGE was prepared using a combination of hot water extraction and microwave-assisted heating. Acute toxicity tests revealed no significant adverse effects at a dose of 3000 mg/kg. The doses of 100, 200, and 400 mg/kg were selected based on preliminary toxicity assessments to systematically investigate the dose-dependent antimalarial efficacy of the extract. Suppressive tests showed that GGE at doses of 100, 200, and 400 mg/kg significantly reduced parasitemia levels, with the highest dose achieving a 63.97% inhibition. In these tests, GGE also increased the mean survival time (MST) of treated mice compared to untreated controls. However, GGE did not exhibit significant curative effects, as parasitemia levels in the treated groups were similar to the untreated control group. Prophylactic tests indicated that GGE pretreatment did not significantly reduce parasitemia levels or improve MST compared to controls, unlike chloroquine (CQ), which demonstrated potent prophylactic efficacy with a significant increase in MST. These findings suggest that while GGE has notable suppressive antimalarial activity, it does not exhibit strong curative or prophylactic effects at the tested doses. This study contributes to the understanding of plant-based antimalarial agents and underscores the importance of continued exploration of natural products for malaria treatment.