Tropical biomedicine最新文献

In Egypt, knowledge about vector-borne bacterial pathogens in camels remains limited. To address this gap, 181 blood samples from adult one-humped camels (Camelus dromedarius) in the greater Cairo metropolitan area were collected from October 2021 to March 2022. Through PCR assays, four pathogens were detected, where Anaplasmataceae being the most common (54.7%), followed by hemotropic Mycoplasma spp. (29.3%), Rickettsia spp. (12.2%), and Coxiella burnetii (1.7%). Comparative sequence analysis revealed novel findings, including: 1) the identification of two distinct hemotropic Mycoplasma spp., one closely related to bovine Mycoplasma sp. (Mycoplasma wenyonii), and the other closely related to porcine Mycoplasma sp. (Candidatus Mycoplasma haemosuis); and 2) the detection of Anaplasma bovis and Anaplasma phagocytophilum. Additionally, Anaplasma platys, Rickettsia africae, and Coxiella burnetii were identified as well. It's worth noting that these vector-borne pathogens possess zoonotic potential, emphasizing the need for adopting a "One Health" approach in Egypt to safeguard the wellbeing of both humans and animals.

Studies have suggested animals as possible reservoir hosts for flaviviruses transmitted by Aedes mosquitoes; however, there is limited evidence for the dengue virus in Malaysia. One of the possible ways to determine the zoonotic potential for any pathogen transmission is through blood meal analysis which can provide valuable insights into the feeding preferences of the mosquitoes. Unfortunately, limited information is available on the feeding preferences of Aedes mosquitoes in Malaysia. Thus, this study aimed to identify the blood-feeding preferences of Aedes aegypti and Aedes albopictus from different ecotypes in Selangor, Malaysia. The field mosquitoes were collected using a modified backpack aspirator and CDC light trap. The collected mosquitoes were initially classified based on degrees of blood digestion according to the Sella scale before extracting the DNA. The presence of vertebrate DNA was detected using nested PCR, and samples positive for vertebrate DNA were further subjected to species-specific PCR targeting the common animals found at the study locations. In general, 51 of 187 field caught Aedes mosquitoes were positive for the presence of vertebrate DNA in their blood meal. The most frequent blood meal source was human (38.2%), followed by monkey (12.7%), bovine (10.9%), chicken (7.3%) and dog (3.6%). The human blood index (HBI) of Ae. albopictus collected across the four different ecotypes revealed that, Ae. albopictus collected near human dwellings showed 100% anthropophilic tendency. Interestingly, there were two Aedes mosquitoes, Ae. aegypti (n=1) and Ae. albopictus (n=1) positive for both human and monkey blood. Since sylvatic dengue continues to flourish in Southeast Asia, this finding from blood meal analysis shows the potential for zoonotic transmission by Aedes mosquitoes in these locations. However, further research must be carried out to understand the role of animals as potential reservoir hosts for the dengue virus, especially through the detection of the virus in the blood meal.

Haplorchis taichui is the minute intestinal fluke (MIF), presents a significant public health concern in Thailand. Despite praziquantel (PZQ) being the main treatment, concerns over recurrent use and drug resistance have surfaced. Thus, local herbal alternatives effective against gastrointestinal parasites could be crucial for reducing issues, necessitating exploration of herbal sources for alternative treatments. The objective of this study is to evaluate the efficacy of crude extracts from Allium sativum, Thunbergia laurifolia, and Eurycoma longifolia against H. taichui newly excysted juveniles (NEJ). H. taichui NEJs were exposed to varying concentrations of A. sativum (5, 10, and 20 mg/ml), T. laurifolia, and E. longifolia (100, 200, and 400 mg/ml), alongside PZQ (20 mg/ml) and RPMI culture medium as controls. Motility assessment at different exposure times and morphological surface changes were conducted by scanning electron microscopy (SEM). Treatment with A. sativum, T. laurifolia, and E. longifolia inhibited motility in H. taichui NEJs, resulting in reduced relative motility (RM) values and survival index (SI). Significant differences were noted in A. sativum and E. longifolia treated groups, with T. laurifolia showing no significant differences compared to the negative control. Morphological damage, especially tegumental swelling, was evident across all treatment groups, notably severe in the A. sativum group. These findings suggest the potential effectiveness of crude extracts of A. sativum, T. laurifolia, and E. longifolia against H. taichui NEJs. However, further investigations are necessary to understand their mechanisms and key bioactive compounds for developing effective anti-parasitic agents against helminthic infections.

Ticks exert a significant economic impact on the livestock industry, particularly in Asian regions. Presently, chemical acaricides constitute the primary method employed to combat tick infestations in livestock, but their use carries adverse environmental consequences. Overreliance on acaricides has contaminated milk and meat products with chemical residues while fostering tick resistance to these agents due to improper and intensive application. Various alternative methods have been explored, including using vaccines to manage tick populations. However, the efficacy of these treatments varies and is often limited when applied separately. Among these alternatives, entomopathogenic fungi like Metarhizium anisopliae appear to be a promising candidate for tick population control. This fungus can be used independently and in conjunction with other products. This review article explores the current and future prospects of M. anisopliae, where the existing gaps and future directives for using this fungus to control hard ticks in Asian countries are highlighted.

Scrub typhus is an infectious disease caused by Orientia tsutsugamushi. It is transmitted through bite of chigger mite larvae and presents with symptoms such as fever, myalgia, headache, rash, and a characteristic eschar at the site of mite bites. This report details the case of a woman exhibiting acute febrile illness, bilateral pneumonia, and severe hypoxemia, prompting suspicion of scrub typhus due to the presence of a typical eschar on the pubic mound. The patient underwent combined therapy with azithromycin and doxycycline, alongside supplemental oxygen and prone positioning, with continuous monitoring facilitated by Electrical Impedance Tomography (EIT). Eventually the patient's symptoms improved. This case highlights the importance of timely identification of ARDS in scrub typhus patients and the utility of EIT in monitoring disease progression.

Bovine anaplasmosis is a tick-borne disease in cattle which is mainly caused by Anaplasma marginale and Anaplasma centrale. It poses significant economic burdens and threat on livestock industries worldwide. This study aimed to identify Anaplasma spp. infecting the commercial Mafriwal cattle in Johor, Malaysia and investigate their phylogenetic relationship in the population. In this study, polymerase chain reaction (PCR) targeting the MSP4 gene for A. marginale and the 16s rRNA gene for A. centrale were performed. These assays were conducted on blood samples collected from 242 Mafriwal cattle. BLAST analysis and phylogenetic trees were constructed to analyze the genetic relationships between the Anaplasma spp. The results revealed 57.85% of the sampled population were infected with Anaplasma spp., 21.90% with A. marginale, 9.50% with A. centrale and 26.45% with both A. marginale and A. centrale. BLAST analysis showed 100% similarities between A. marginale sequences from this study and the sequence from a goat in Brazil. Similarly, A. centrale sequences were closely related to strains from tick vector, Rhipicephalus (Boophilus) microplus in Panama with 100% similarity. Phylogenetic analysis confirmed distinct clades for A. marginale and A. centrale, indicating genetic diversity and specific species differentiation. The findings highlight the endemicity of bovine anaplasmosis in Malaysian cattle populations and potential cross-border transmission routes. Moreover, this study provides the first report of A. centrale prevalence in Malaysia, emphasizing the importance of ongoing surveillance and management efforts. Understanding the genetic diversity and species differentiation of these pathogens is crucial for designing effective control strategies and vaccine development. In conclusion, this study enhances our understanding of the prevalence and genetic dynamics of bovine anaplasmosis among Mafriwal cattle in its largest population in Malaysia for better diagnosis and effective control measures.

Anaplasma species are obligate rickettsial intraerythrocytic pathogens that cause an important tick-borne disease of economic importance in livestock production in many countries. Anaplasma species have been detected from farm animals worldwide, there is a paucity of information on Anaplasma infections in goats from Malaysia. Thus, this study aimed to assess the infection rate and identify Anaplasma species and some selected risk factors in goats across selected districts in Kelantan, Malaysia. A total of 411 blood samples were collected from goats and analysed for Anaplasma species targeting the msp4 gene using conventional PCR and sequencing. The infection risk was determined by breed, age, management system and location. Our results indicate an overall infection rate of 30.9% for Anaplasma species detected. Interestingly, sequencing of selected amplicons revealed the presence of Anaplasma ovis and A. marginale. Data analysis revealed a marked statistically significant association between Anaplasma infection and some variables such as location (district), farm management system, breed, and age (P < 0.05). Specifically, goats raised on intensive management had the highest prevalence of 46.25% (37/80) compared to other management types. Also, with regards to district, goats raised in the coastal region had a higher prevalence of 39.23% (71/181) compared to those raised in inland region 24.35% (56/230). Regarding breed, goats that were of the pure breed had a higher prevalence of Anaplasma species infection 38.19% (97/254) compared to crossbreeds with a prevalence of 19.11% (30/157). Lastly, goats 3 years had the least prevalence 18.99% (34/179). To the best of our knowledge, this is the first report of A. marginale and A. ovis in goats from northeastern Peninsular Malaysia. The infected goats were clinically healthy; this revealed the role of goats as a potential reservoir for A. marginale and the presence of A. ovis in goats in Malaysia. Continuous efforts towards tick control must be sustained to ensure high productive yield and reduced disease burden associated with TBPs of goats in the study area.

In light of the adverse effects of chemical insecticides on the environment and human health, as well as the development of mosquito resistance to them, this study explores the potential of methanol and aqueous flower extracts from Lavandula dentata and Nerium oleander as bioinsecticides against Culiseta longiareolata mosquitoes. Additionally, it aims to assess the impact of these extracts on enzymatic biomarkers and biochemical composition of fourth instar larvae of Culiseta longiareolata.Qualitative analysis revealed the presence of flavonoids, terpenes, gallic and catechic tannins in both plant extracts. Sterols and quinones were exclusively found in L. dentata, while saponins were identified in N. oleander. methanolic extracts demonstrated higher yields compared to aqueous extracts. The results showed significant larvicidal activity for all the tested extracts, the LC₅₀ values after 24 hours are: 463.8; 338.1; 760.9 and 99.64 ppm for the aqueous and methanolic extract of L. dentata and N. oleander respectively. This proves that the methanolic extracts of N. oleander and L. dentata have higher efficacy against C. longiareolata compared to the aqueous extracts. Enzymatic activity assays conducted on larvae treated with various extracts, particularly at LC₂₅ and LC₅₀ concentrations, indicated an induction of the detoxification system, evidenced by increased glutathione S-transferases (GSTs) and catalase activity. Morphometric analysis revealed a significant reduction in the growth of fourth-stage larvae treated with these extracts. As well as a notable decrease of a percentage ranging from 44.23 to 83.30% in protein content; a reduction between 38.15-78.57% in carbohydrates and a percentage decrease of 23.85 to 63.58% in lipids. These findings suggest that the observed effects may be attributed to the stressful conditions imposed by the treatment, necessitating additional energy supply from carbohydrate and lipid metabolism in the larvae.

Dengue, caused by the dengue virus (DENV), poses a significant global health challenge. Effective vaccines and treatments for dengue are lacking due to gaps in understanding its pathogenesis and mechanisms in severe cases. This study investigates the role of immunoglobulin E (IgE) in dengue, focusing on its potential association with virus neutralization and antibody-dependent enhancement (ADE) in DENV replication. Serum samples were obtained from dengue-positive (dengue-IgG positive), SLE (dengue-IgG negative), and control (dengue-IgG and SLE-negative) individuals. SLE sera were included as a control for their high total IgE levels. Total IgE and dengue-specific IgE levels were measured using ELISA. Neutralization assays in Vero and KU812 cells were conducted to assess virus neutralization and ADE, respectively. Dengue-positive and SLE sera showed higher total IgE levels than control sera, although there was no significance seen. Dengue-positive sera showed the presence of dengue-specific IgE, whereas SLE and control sera exhibited negligible levels. Neutralization assay in dengue-positive sera revealed no correlation between IgE levels and virus inhibition. SLE sera, however, demonstrated an inverse correlation between total IgE levels and DENV neutralization, suggesting a potential involvement of total IgE in DENV replication in the context of SLE. Seventy-eight percent of SLE sera, 65% of denguepositive and 54% of control sera exhibited enhanced virus replication in KU812 cells with serum compared to virus alone, indicating the highest occurrence of ADE in SLE, followed by dengue-positive and control sera. DENV expression in KU812 cells was notably higher in SLE sera, indicating increased ADE risk. However, no association was found between IgE levels and virus expression in KU812 cells across all groups. The inverse correlation between total IgE levels and DENV neutralization in SLE sera suggests that IgE may facilitate virus replication. Further comprehensive exploration is needed to fully understand the role of IgE in dengue pathogenesis.

Numerous human diseases, including those caused by viruses like Nipah virus and SARS-CoV, can be traced back to bats as their origin. Malaysia, notably Sabah and Sarawak in Borneo Island, is home to a rich diversity of bats that serve as hosts for various viruses. This comprehensive review represents the inaugural exploration of viruses found in Malaysian bats, as documented in scientific journals. It also encompasses documented instances of bat virus-related disease outbreaks in Malaysia up to the present day, along with an analysis of the risk factors associated with virus spillover events. Furthermore, this review offers insights into prospective research areas of significance and suggests potential mitigation strategies.