Tropical biomedicine最新文献

Leishmaniasis causes significant morbidity and mortality worldwide. In our country, there has been a significant increase in the number of cases of leishmaniasis in the last decade. In our study, the effects of Hypericum thymbrifolium, Hypericum scabrum and Eryngium creticum plant extracts were tested on Leishmania major, Leishmania tropica and Leishmania infantum/donovani, which were clinically resistant by not responding to Glucantime® therapy. Cytotoxicity of these extracts were evaluated by XTT method in the human fibroblast cell line. Possible active ingredients were detected by GC-MS analysis from plant extracts. Glucantime® resistance was detected at concentrations of 50 µg/mL and lower in 4 of the 7 strains tested. No living leishmania parasites were found in leishmania strains treated with plant extracts at concentrations of 100 µg/mL or higher. The concentrations of plant extracts included in the study on the WI-38 human fibroblast cell line were not cytotoxic. According to the GC-MS analysis, several active substances with biological activities and anti-parasitic effects, such as Thiophene, Germacrene-D, trans-Geranylgeraniol, Pyridine, and Maleimides, were identified. Based on the findings of the study, it is believed that these identified active substances when supported by in-vivo studies, will pave the way for future research and have the potential to be developed as anti-leishmania drugs.

Infectious diseases with complications of sepsis are still public health concern in both developed and developing countries. Sepsis is a potentially life-threatening systemic immune response to infection that can lead to end- stage organ failure and death. Sepsis involves multiple mechanisms such as neuroendocrine, complement activation, blood coagulation, and fibrinolytic system. Reactive oxygen species (ROS) is an inflammatory mediator produced by NADPH oxidase activation. This study aimed to investigate the effects of ethanol extract of E. elatior fruits on NADPH oxidase activity. Forty Mus musculus mice were randomized divided into five groups (n=8), with the intervention group receiving an intraperitoneal injection of 0.3 mg/kg BW lipopolysaccharide (LPS). There was a normal group without LPS injection (N-1), LPS injection only (N-2), and those that received LPS injection and ethanol extracts of E. elatior fruits containing 2.1 mg/20 g (N-3), 4.2 mg/20 g (N-4), and 8.4 mg/20 g (N-5). NADPH oxidase activity were measured using ELISA. The oneway ANOVA was used to investigate the differences between the groups. After administration of the extract at a varied dose, N-5 group the lowest NADPH oxidase activity (p=0.001). The ethanol extract of E. elatior fruit has antioxidant effects. In this study, a dose of 8.4 mg/20 g of extract significantly reduced NADPH oxidase activity. The ethanol extract of E. elatior might be considered a treatment in sepsis.

Post-mortem microbiology (PMM) is an important tool in identifying possible causes of sudden unexpected death, as an infectious cause is highly suspected. However, contamination is a major problem in microbiology, and this has increased the difficulty determining the true pathogen that contributes to death in post-mortem cases. Skin commensals are common contaminants in blood cultures. This study was conducted to investigate the skin flora on early deceased bodies and observe the bacteria detected at different post-mortem intervals (PMIs). As blood is usually drawn from the neck and femoral sites for PMM examination, the two body sites were chosen as the sampling sites. Skin swab samples from the neck and femoral (n=80) of each early deceased body were collected by sterile cotton swabs. DNA was extracted from the swabs and then subjected to high-throughput 16S rRNA sequencing by using the Illumina MiSeq platform. Staphylococcus was found to be the most dominant genus in both neck and femoral sites. LEfSe results showed that Cutibacterium is significantly different at the neck site while Corynebacterium is more abundant at femoral site. There are significant differences at genus level between PMI<5H and PMI>5H at both neck and femoral sites. The findings of the present study may act as a reference for microbiologists and forensic pathologists when mixed growth or contamination occurs in post-mortem blood cultures.

Dengue is a mosquito-transmitted infection endemic in tropical and subtropical locations of the world where nearly half of the world's population resides. The disease may present as mild febrile illness to severe and can even be fatal if untreated. There are four genetically related but antigenically distinct dengue virus (DENV) serotypes. Immune responses to DENV infection are in general protective but under certain conditions, they can also aggravate the disease. The importance of the cellular immune responses and the antibody responses involving IgG and IgM has been well-studied. In contrast, not much has been described on the potential role of hypersensitivity reactions involving IgE in dengue. Several studies have shown elevated levels of IgE in patients with dengue fever, but its involvement in the immune response against the virus and disease is unknown. Activation of mast cells (MCs) and basophils mediated through dengue-specific IgE could result in the release of mediators affecting dengue virus infection. The present review explores the relationships between the induction of IgE in dengue virus infection, and the potential role of MCs and basophils, exploring both protective and pathogenic aspects, including antibody-dependent enhancement (ADE) of infection in dengue.

Avian infectious bronchitis (IB), a Gammacoronavirus, is a highly contagious upper respiratory disease, affecting chickens of all ages with a significant economic threat to the poultry industry. In February 2020, a specimen of imported chicken meat product was received and requested for coronavirus testing. The result was positive for the avian coronavirus, the IB virus (IBV) by molecular detection in the pre-screening test. Thus, this study aimed to isolate and characterize the IBV from the specimen. Virus isolation via egg inoculation was attempted and IBV was successfully isolated. The S1 subunit of the spike (S) gene of the IBV was amplified, sequenced, and the Basic Local Alignment Search Tool (BLAST) analysis showed that the IBV has 99% and 98% nucleotide similarity with the Malaysian and China IBVs, respectively. The phylogenetic analysis indicated that the virus belongs to the GI-19 lineage (also known as the QX strain) and is grouped with other IBVs from Malaysia and China. The GI-19 lineage is one of the primary IB strains that circulate in Malaysia. The recovery of the virus may be due to the persistence characteristic of the virus on meat; and the cold chain practices in the imported food product prolong the survival of this coronavirus. Though IBV is not identified as a hazard in chicken meat or meat products, raw food should be cooked thoroughly before being consumed. With the increase in international trade in poultry and poultry products, disease screening at the entry point and import risk analysis is crucial to ensure food safety and prevent the introduction of new viruses into Malaysia.

Streptococcus suis is a bacterium of clinical importance in diverse animal hosts including companion animals and humans. Companion animals are closely associated in the living environment of humans and are potential reservoirs for zoonotic pathogens. Given the zoonotic potential of S. suis, it is crucial to determine whether this bacterium is present among the companion animal population. This study aimed to detect Streptococcus suis in companion animals namely cats and dogs of the central west coast of Peninsular Malaysia and further characterize the positive isolates via molecular and genomic approach. The detection of S. suis was done via bacterial isolation and polymerase chain reaction assay of gdh and recN gene from oral swabs. Characterization was done by multiplex PCR serotyping, as well as muti-locus sequence typing, AMR gene prediction, MGE identification and phylogenomic analysis on whole genome sequence acquired from Illumina and Oxford Nanopore sequencing. Among the 115 samples, PCR assay detected 2/59 of the cats were positive for S. suis serotype 8 while all screened dog samples were negative. This study further described the first complete whole genome of S. suis strain SS/UPM/MY/F001 isolated from the oral cavity of a companion cat. Genomic analysis revealed a novel strain of S. suis having a unique MLST profile and antimicrobial resistance genes of mefA, msrD, patA, patB and vanY. Mobile genetic elements were described, and pathogenic determinants matched to human and swine strains were identified. Phylogenetic tree analysis on the core genome alignment revealed strain SS/UPM/MY/F001 was distinct from other S. suis strains. This study provided insight into the detection and genomic features of the S. suis isolate of a companion cat and highlighted its potential for antimicrobial resistance and pathogenicity.

The study aimed to compare and correlate serum levels of IL-6, 10, and 25-hydroxycholecalciferol in individuals with asthma with and without post-COVID condition (PCC). The study was designed to investigate the inflammatory response and serum 25-hydroxycholecalciferol status in asthmatics with and without PCC. A cross-sectional study of 252 subjects (128 asthmatics and 124 non-asthmatic subjects) was carried out. Interleukins and 25-hydroxycholecalciferol levels were estimated on ELISA. The principle findings were that IL-6 and 25-hydroxycholecalciferol levels were significantly increased (p<0.001), while IL-10 levels were non-significant in asthmatics with PCC compared to those without PCC. However, 25-hydroxycholecalciferol levels were significantly increased, but no significant change was observed in IL-6, and IL-10 levels in non-asthmatics with and without chronic PCC. A significant positive correlation (r = 0.258) was found between 25-hydroxycholecalciferol and IL-6 but a significant negative correlation (r = -0.227) with IL-10 in asthmatics with PCC. Similarly, a significant negative correlation (r = -0.285) was found between 25-hydroxycholecalciferol and IL-10 but was non-significant with IL-6 in asthmatics without PCC. The correlation of 25-hydroxycholecalciferol with IL-10 was significant (0.683), but IL-6 was non-significant in non-asthmatics with PCC. Multiple regression analysis showed that age, IL-6, gender, and PCC were significantly related in adjusted values to 25-hydroxycholecalciferol. This study sheds light on the complex liaison between 25-hydroxycholecalciferol levels and inflammatory responses in asthmatics, especially those with PCC. The findings suggest that although asthmatics with PCC maintain sufficient levels of 25-hydroxycholecalciferol, they show a substantial increase in the proinflammatory response. This suggests that PCC exacerbates the pro-inflammatory response in asthma. Moreover, the study reveals that asthmatics, whether with or without PCC, display a negative correlation between 25-hydroxycholecalciferol and the anti-inflammatory response. This emphasizes the main influence of asthma on the overall inflammatory response. These findings reveal a complex interplay between vitamin D levels and inflammatory mediators in asthmatic individuals with and without PCC.

The present study aimed at exploring whether sunlight exposure might account for the relative difference in COVID-19-related morbidity and mortality between tropical and non-tropical countries. A retrospective observational study was designed and data from the World Health Organization weekly COVID-19 epidemiological update was compiled. We examined the total number of confirmed COVID-19 cases per 100 000 population, as well as the total number of COVID-19-related mortalities per 100 000 population. Solar variables data were obtained from the Global Solar Atlas website (https://globalsolaratlas.info/). These data were analyzed to determine the association of sunlight exposure to COVID-19-related morbidity and mortality in tropical and non-tropical countries. Results revealed a statistically significant decrease in the number of confirmed COVID-19 cases per 100 000 population (P<0.001), as well as the number of COVID-19-related mortalities per 100 000 population (P<0.001) between tropical and non-tropical countries. Analyses of sunlight exposure data found that specific photovoltaic power output, global horizontal irradiation, diffuse horizontal irradiation and global tilted irradiation at optimum angle were significantly inversely correlated to COVID-19-related morbidity and mortality. This suggests that stronger sunlight exposure potentially leads to lower COVID-19-related morbidity and mortality. Findings from this study suggest that the relatively low COVID-19-related morbidity and mortality in tropical countries were possibly due to better sunlight exposure that translates into adequate vitamin D status.

Water pollution in developing countries continues to be a major health problem due to various anthropological activities that contribute to the spread of many parasitic diseases, including those caused by helminths. The aim of this study is to explore the ability of ozone and peroxone to disinfect drinking water contaminated samples with Toxocara canis eggs. The oxidants used were ozone and ozone-hydrogen peroxide combination. The treatment of Toxocara canis eggs was carried out in a 50 ml reactor with an operating volume of 10 ml. The pH conditions (5, 7 and 10) were varied for each treatment. The treatment effect was calculated by counting eggs and examining the condition of the larvae larval condition (whole, broken and hatched larvae) using an optical microscope. The experiment was carried out by exposing the eggs for 60 and 120 minutes to ozone and peroxone. The best results were obtained for helminths treated with the ozone/hydrogen peroxide combination at pH 10, with an inactivation of 79.2%. The synergistic effect of ozone combined with hydrogen peroxide allows higher helminth egg inactivation rates, demonstrating that advanced oxidation processes are a real alternative to apply in the inactivation of Toxocara canis eggs. The results obtained in this study show that the ozone and peroxone treatment could be a useful disinfection process to destroy or inactivate Toxocara canis eggs in processes commonly applied in water treatment.

Culicoides oxystoma Kieffer is a vector of viruses, filarial nematodes and protozoa of the genus Leishmania transmitted to humans and other animals. Understanding genetic diversity, genetic structure and genetic relationships among geographically widespread populations will provide important information related to disease epidemiology. In this study, genetic diversity, genetic structure and genetic relationships between Thai C. oxystoma and those reported from other countries were inferred based on mitochondrial cytochrome oxidase I (COI) and nuclear internal transcribed spacer 1 (ITS-1) sequences. A high level of genetic diversity was found in C. oxystoma from Thailand. The maximum K2P intraspecific genetic divergence for COI gene and ITS-1 sequences were 4.29% and 6.55%, respectively. Despite high genetic diversity, no significant genetic differentiation was found within the 13 Thai populations. This could be a result of unspecialized habitat requirement of the larval habitat, abundance and continuous distribution of host blood sources, potential for long distance movement with host via trading. Mitochondrial genealogy analysis of the global population of C. oxystoma revealed three (A, B and C) genetically divergent lineages. Specimens from Thailand were included in the main lineage (A) with those from all other countries except those from Senegal that formed lineage B and those of Lineage C that was exclusively found in Bangladesh. The nuclear (ITS-1) genetic markers genealogy indicated that Thai C. oxystoma belong to the same genet.