Tropical biomedicine最新文献

Mosquito-borne diseases have wreaked havoc on human health, with consequences dramatically increasing in recent years. The incidence of mosquito-borne diseases is closely linked to the locations that are chosen for urban development. The aim of this study was to provide characteristics of mosquito breeding sites in northern and southern China and to document the most important arbovirus vectors found in the study area, the evidence generated here is critical for early prevention and control inter ventions. This research involved a random selection of various sites across four provinces, spanning both the northern and southern regions of China. The dwellings and accessible water storage containers in these sites were investigated to detect the presence of immature mosquitoes. Samples were then collected, mosquitoes were nurtured to adulthood, and the species that were present were identified. A total of 1 249 samples were collected during this survey of the mosquito breeding sites. A total of 80 samples were processed using the Chelex method to extract mosquito DNA from all the samples. The ITS2 gene fragment was then amplified by PCR and sequenced. A subsequent BLAST comparison allowed the identification of the mosquito species, and MEGA11 software was used for phylogenetic analysis. The results showed that there were four species of mosquitoes, including Aedes albopictus, Culex quinquefasciatus, Lutzia fuscanus and Armigeres subalbatus. The primary mosquito breeding grounds in the four provinces of China consisted of storm drains, discarded containers, garbage bins, and areas with standing water. Still-water environments, such as rice fields were the primary breeding locations in the southern cities. In contrast, in the northern regions, most breeding occurred at construction sites, and in similar water-prone areas. The most prevalent mosquitoes in the four provinces of China were of the genus Aedes, with a significant number originating from Fujian Province, China. This information sheds light on the migration patterns of mosquitoes and significantly enhances community-based protection measures and mobilization efforts.

The increasing prevalence of multidrug-resistant bacteria necessitates the exploration of novel antimicrobial agents. This study aims to investigate the antibacterial and antibiofilm properties of mucus from Helix aspersa, a species of terrestrial snail, against multidrug resistant Staphylococcus aureus strains. The antibacterial effect was assessed using well diffusion, microdilution, and time kill assays. The antibiofilm effect was assessed using crystal violet staining. Protein profiling was conducted through SDS-PAGE Electrophosis to determine the molecular weights of the mucus proteins. The results show that Helix aspersa mucus has potent anibacterial properties with inhibitory diameters ranging from 18.67±1.53 to 25.16±1.04 mm, and MIC and MBC values ranging from 3.12 to 6.25 (v/v). The MBC/MIC values from 1 to 2 and the time kill curve demonstrated that Helix aspersa mucus has a bactericidal effect. It has also a significant antibiofilm effect as it could inhibit the formation of biofilms at percentages ranging from 88.46±0.96% to 94.93±1.48% and eliminate biofilm at percentages ranging from 79.69±1.36% to 91.38±1.80%. Protein profiling of the mucus revealed the presence of three distinct proteins with molecular weights of 29.0, 81.1, and 106.4 kDa, which are likely responsible for these bioactive properties. Helix aspersa mucus could serve as a promising natural antimicrobial agent, offering potential applications in treating infected wounds caused by multidrug resistant bacteria.

Strongyloidiasis is a parasitic nematode infection mainly caused by Strongyloides stercoralis. Immunocompromised conditions, particularly cancer patients treated with chemotherapy and corticosteroids, have a significant risk of developing Strongyloides hyperinfection. The lack of a gold standard laboratory method to rule out this infection and the insensitivity of microscopic stool examination due to low and intermittent larvae output in stool contribute to the low detection rate of this infection. We present three cases of strongyloidiasis in adults with haematological malignancies and significant eosinophilia in the early course of their cancer. Two patients were diagnosed with a combination of serological and molecular tests, and one was diagnosed serologically. Ivermectin at 200 mcg/kg/day for two days was commenced for all patients; unfortunately, one patient succumbed.

Leptospirosis is a severe and potentially fatal re-emerging zoonotic and waterborne disease caused by pathogenic and intermediate species of Leptospira. Given the high global rates of morbidity and mortality associated with this disease, there is an urgent need to explore alternative therapeutic agents to enhance treatment options. This study investigates the anti-leptospiral efficacy of several common antibiotics-penicillin G, doxycycline, ampicillin, amoxicillin, cefotaxime, chloramphenicol, and erythromycin, as well as extracts from local herbs, Hydnophytum formicarum Jack and Boesenbergia stenophylla, against pathogenic and intermediate Leptospira strains. A broth microdilution method determined the minimum inhibitory concentration (MIC) for the antibiotics and herb extracts. Both herbs were extracted using four different solvents: ethyl acetate, methanol, hexane, and chloroform. The extracts were then analysed using gas chromatography-mass spectrometry (GC-MS) to identify their phytochemical compounds. The results demonstrated that cefotaxime and erythromycin exhibited the highest anti-leptospiral activity, with MIC values of 0.2 µg/mL. This was followed by amoxicillin and ampicillin (0.2-0.39 µg/mL), penicillin G (0.39-3.13 µg/mL), chloramphenicol (0.78-3.13 µg/mL), and doxycycline (0.78-12.5 µg/mL). H. formicarum Jack and B. stenophylla extract extractions displayed the lowest MICs (62.5 µg/mL) for the ethyl acetate, methanol, and hexane extracts. They contained various phytochemical constituents, including some with anti-leptospiral properties. These findings indicate that different strains of Leptospira respond with varying levels of inhibition to the antibiotics and herb extracts studied. The extracts from H. formicarum Jack and B. stenophylla may have potential as anti-leptospiral drugs. However, further in-vivo studies are needed to better understand their efficacy against Leptospira.

The use of Streptomyces secondary metabolites for mosquito control has recently received positive attention. Accordingly, this study was performed to elucidate the cellular, genomic and biochemical responses of Aedes mosquitoes to Streptomyces sp. KSF103 ethyl acetate (EA) extract, a mixture previously characterized for its potential bioactivity. Through flow-cytometry based apoptosis assay, EA extract elicited apoptosis-mediated cell death in C6/36 cells of Aedes albopictus. Microarray analysis on Ae. aegypti larvae and adults revealed the potential involvement of tropomodulin and sestrin, which was validated by quantitative real-time RT-PCR, suggesting apoptosis induction in response to the EA extract. Functional analysis suggested that MAPK and Notch signaling pathways are linked to apoptosis. On the other hand, biochemical assays demonstrated acetylcholinesterase (AChE) inhibition in both larvae and adults, suggesting the toxicity disrupted their nervous system. In conclusion, this study has revealed the promising bioactivities of a Streptomyces-derived insecticide, providing insights into the mechanisms involved and emphasizing its potential significance in mosquito control.

Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection, with resistance to antimalarial drugs, including artemisinin-based combination therapies(ACTs), posing a significant threat. CD4+ naive cells expressing CCR7 are known to play a protective role, as they readily migrate to secondary lymphoid tissues activated by CCL19 chemokines. In an effort to address this challenge, we investigated the impact of Annona muricata, an herbaceous and immunomodulatory plant, on CCL19 concentration. We conducted experiments on 24 mice, dividing them into four groups: one control group and three treatment groups. Groups 1 and 3 received a daily dose of 4.68 mg of Annona muricata leaf water extract (AM) for seven days before CM infection. After seven days of treatment, all groups were infected with CM. Groups 1 and 3 continued with a 9.36 mg AM dosage for an additional seven days, while groups 2 and 3 received a 0.819 mg ACTs dosage on the fourth day post-infection. We analyzed the CCL19 content in the mice's spleens and evaluated the data using Bonferroni post hoc, Kruskal-Wallis, and Mann-Whitney U tests. Our results demonstrated that the CCL19 levels in the AM-ACTs group significantly surpassed those in both the control group (p = 0.009) and the ACTs group (p = 0.002). This suggests that the combination of AM and ACTs led to a notable increase in CCL19 levels in Swiss mice afflicted with CM. While further research is necessary to validate and expand upon these findings, our study highlights the potential of AM to enhance CCL19 production, potentially facilitating the migration of naive T cells and reinforcing the immune response.

The deer fly (Diptera, Tabanidae), Chrysops dispar Fabricius is a common and widespread pest and vector species transmitting pathogens to animals including economically significant livestock. However, there is only limited information on genetic diversity, which crucial for understanding disease epidemiology. In this study, we examined genetic diversity of C. dispar collected from northeastern Thailand and compared with Indian material, from where this species was originally described. A molecular approach was used to screen for trypanosome. High genetic diversity was found within Thai C. dispar specimens with maximum 3.10% intraspecific genetic divergence due to the existence of two cryptic genetic lineages. Because these lineages coexist geographically, this indicates some degree of isolation, or the early stage of speciation. Phylogenetic analyses between Thai and Indian C. dispar populations revealed that they are genetically clearly distinct with minimum genetic divergence of 2.59%. A molecular species delimitation analysis supported that they belong to different species. Molecular screening of trypanosomes revealed that 20 of 90 specimens were positive and 16 of these were successfully sequenced. Based on sequence similarity, all were belonging to Trypanosoma theileri complex detected in cattle, the first report of this parasite in C. dispar. Phylogenetic analyses revealed that they belonged to two lineages (TthI and TthII) of this protozoa, corresponding to the occurrence of this parasite found in cattle in Thailand.

House Dust Mites (HDMs) like Dermatophagoides farinae (D. farinae), Dermatophagoides pteronyssinus (D. pteronyssinus) and Blomia tropicalis (B. tropicalis) were found all over the world. Their relationship with allergy diseases was one of the focal points of epidemiological investigations spanning various geographical regions globally but specifically in regions with warm temperatures. Their omnipresence underscores their pivotal role in the etiology and exacerbation of some respiratory disorders, emphasizing their significance as environmental allergens. Despite the availability of numerous eradication treatments ranging from sun exposure to ozone-based approaches, the quest for efficacious HDM eradication encounters obstacles due to the diversity in study methodologies employed to evaluate these different intervention strategies. This methodological heterogeneity complicates the quantification of treatment efficacy, impeding the establishment of definitive criteria distinguishing "effective" from "ineffective" approaches. Despite the urgency of developing solutions, current efforts are hindered by this lack of consensus. This review aims to bridge this gap by synthesizing existing knowledge on HDM eradication strategies and discussing their efficacy, safety, and practicality. By addressing these discrepancies, this article endeavors to provide insights and clues for the future development of evidence-based interventions aimed at mitigating HDM infestations and ultimately reducing its sensitization rate worldwide.

Migratory birds are potential vectors transmitting zoonotic parasites, bacteria, and viruses that can significantly affect human health. Over 60 diseases have been identified to be associated with these birds. Given their close proximity to human habitation, the potential transmission of zoonotic diseases is a major concern for the public. In this study, we aimed to assess the prevalence of intestinal parasites in the droppings of the Barn Swallow, Hirundo rustica, a bird species that annually migrates to Malaysia. Eighty droppings from H. rustica were collected; 13.75% of the samples were found to be positive for various parasites, including Ascaridia galli (8.75%), Eimeria sp. (2.5%), Hymenolepis spp. (1.25%), and Toxocara spp. (1.25%). These findings offer valuable insights into the current prevalence of bird parasitic infections. They can serve as a crucial resource for implementing effective control measures, devising prevention strategies, and predicting future outbreaks of parasite infections transmitted by birds.

Opisthorchis viverrini poses a substantial risk for cholangiocarcinoma (CCA) in Thailand. Despite praziquantel (PZQ) remains the primary treatment for opisthorchiasis, its association with adverse effects and potential CCA development during prolonged treatment, particularly in cases of reinfection and chronic infection, underscores the imperative for alternative herbal interventions with anthelmintic potential. In this context, a prior study suggested the inhibitory effects of Allium sativum L. (garlic) on various protozoa and helminths, prompting the investigation of its efficacy against O. viverrini in this study. Therefore, this study aimed to assess the efficacy of garlic against O. viverrini. O. viverrini adult worms were exposed to varying concentrations of garlic crude extract (20, 30, and 40 mg/ml). As comparators, another set of adult worms was treated with PZQ (20 mg/ml) and Roswell Park Memorial Institute 1640 medium, serving as the positive and negative control groups. The quantification of reactive oxygen species (ROS) as markers of oxidative stress was executed using 2',7'-Dichlorodihydrofluorescein diacetate staining. Morphological damage of O. viverrini adult worms were evaluated through scanning electron microscopy. Additionally, motility assessment was conducted at various exposure times (0, 30 minutes, 1, 2, 3, 6, 12, and 24 hours) by estimating relative motility values and survival index. The results revealed significantly elevated ROS levels and distinctive morphological damage, characterized by swelling of microvilli and papillae in the garlic-treated groups. In contrast, the positive control group exhibited minor morphological damage, while the negative control group did not display such alterations. The reduction in movement and increased mortality were observed in the groups treated with garlic, as evidenced by the RM and SI values, in comparison to both the positive and negative control groups. These findings suggest that garlic extract possesses potent anthelmintic properties against O. viverrini adult worms and holds promise as an alternative therapeutic avenue for Opisthorchiasis.