Tropical biomedicine最新文献

Four new species of black flies are described based on the females, males and pupae from Sumatra, Indonesia, and are assigned to three species-groups in two subgenera of the genus Simulium Latreille s. l.: Simulium (Gomphostilbia) kandisense sp. nov. in the S. asakoae species-group, S. (Simulium) kotsuboyui sp. nov. and S. (S.) solokense sp. nov. in the S. iridescens species-group, and S. (S.) bengkuruense sp. nov. in the S. striatum species-group. The two new species in the S. iridescens species-group and one new species in the S. striatum species-group were formerly regarded as S. (S.) iridescens De Meijere and S. (S.) argyrocinctum De Meijere, respectively, in Sumatra, although these two species were originally described from Java and later recorded from Sumatra. The number of male upper-eye (large) facets, the presence or absence of tubercles on the pupal head and thorax, and the arrangement and relative thickness of pupal gill filaments were useful for separating these three new species from the two known species. This study increased the number of species of black flies in Sumatra from 27 to 31. However, records of some old species including S. (S.) iridescens and S. (S.) argyrocinctum should be reconfirmed for their distribution in Sumatra by future surveys.

Pediculosis capitis remains a neglected public health issue in Malaysia, particularly among disadvantaged children. While the genetic diversity of head lice is well studied, their associated microbiome and links to socio-sanitary conditions remain unclear. This study examined 266 children from ten children's establishments in Klang Valley and Greater Kuala Lumpur, of whom 89 (33.46%) were positive for pediculosis capitis. Cytochrome c oxidase subunit I (COI) barcoding identified two clades: A (36%) and C (64%). 16S rRNA metagenomic profiling of pooled samples revealed higher microbial diversity in Clade C compared to Clade A, with opportunistic bacteria, including Propionibacterium acnes, Streptococcus spp., Bacteroides fragilis, and Staphylococcus aureus being detected. Logistic regression identified age, head lice awareness, and eating with hands as significant predictors of infection. These findings demonstrate that head lice not only cluster genetically but also may harbour clade-dependent microbiomes, with potential health implications. The integration of genetic diversity, microbial variation, and socio-sanitary data highlights the multifactorial risks of pediculosis capitis in vulnerable populations, underscoring the importance of combined ectoparasite control and hygiene interventions.

Human brucellosis is an acute febrile illness responsible of causing serious threats to pregnant women and their developing fetus. It is a neglected disease having zoonotic potential resulting in variety of complications. The present study aimed to detect sero-prevalence of brucellosis in pregnant women and to find out the role of various demographic and potential risk factors associated with this disease during January to July 2024. In this cross-sectional study (n=300) blood samples were collected from pregnant women ranging from 18 to 45 years of age. The information about personal data, demographics and risk factors was gathered via pre-designed structured questionnaire. The anti-Brucella antibodies were detected using Rose Bengal Plate test (RBPT) followed by enzyme linked immunosorbent assay (ELISA). The seropositive samples were subjected to qRT-PCR for molecular detection of Brucella. The data was subjected to descriptive statistics, Chi square test and Odds ratio using Minitab version 18. The result of study showed the sero-prevalence of brucellosis 9.33% among pregnant women with higher 11.36% in age group (18-28 years). Among the demographic factors, the occupation of farming (P =0.005; OR = 3.51, 95%CI: 1.56-7.85) and absence of education (P = 0.001; OR = 7.20, 95%CI: 2.79-18.59) showed significant association with human brucellosis. Additionally, of the potential risk factors analyzed, keeping animals at home (P =0.001; OR = 4.64, 95%CI: 2.05-10.50), and lack of knowledge about brucellosis (P =0.047; OR = 3.53, 95%CI: 1.03-12.03) were found statistically significant. A comprehensive awareness should be given to females regarding risk factors and spread of brucellosis. Consumption of pasteurized dairy products and adopting personal protection while dealing with animals will prevent pregnant women and their unborn from human brucellosis and its complications.

5 Soil-transmitted helminth (STH) infections remain a significant global health concern due to their high prevalence in many areas and ease of transmission via the fecal-oral route. To control and enhance the declining helminth infection rate in children, Indonesia initiated a nationwide mass drug administration (MDA) in 2017, encompassing rural areas such as Southwest Sumba (SWS). Nevertheless, the prevalence of STH in SWS remained at 54% by 2021. Children are particularly susceptible owing to frequent exposure to helminth-egg-contaminated environments, which may lead to nutrient deficiencies. Therefore, we sought to assess STH prevalence in this post-MDA period and to investigate the impact of STH infection on anemia, nutritional status, and hygiene practices among preschool-aged children (PAC) and schoolaged children (SAC) in Hameli Ate and Homba Karipit Villages, North Kodi District. A total of 223 stool samples were examined using the Kato-Katz technique, revealing an overall STH prevalence of 58.3%, with the majority of children exhibiting light infections (Ascaris lumbricoides: 37.7%; Trichuris trichiura: 26.5%). Infection rates were notably higher in younger SAC (26.6%; 34/128) and older SAC (40%; 10/25) compared to PAC (21.1%; 8/38) groups. Despite this, 67.9% of the children had normal nutritional status, and 61.5% were found to be non-anemic. There was a significant correlation between maternal education and STH infections (OR = 0.4; 95%CI = 0.2-0.79; p = 0.016). A highly educated mother would improve children's hygiene, subsequently contribute to the reduction of infection severity and enhance the child's health. Altogether, our findings indicate the high burden of STH infection on children in this rural area. Thus, this study emphasize the importance of the re-evaluation of the MDA program and improvement of hygiene facilities, such as clean water and sanitation, to mitigate disease risk and promote children's health.

Malaria is a global public health concern, where Plasmodium knowlesi contributes to most human malaria cases in Malaysia. The leaves of Vernonia amygdalina (Delile) were found to exhibit significant anti-plasmodial properties and are commonly used in sub-Saharan Africa countries for malaria treatment. Nonetheless, studies are lacking in the effect of this plant against P. knowlesi specifically. This study aimed to investigate the in vitro anti-plasmodial activity of crude extracts from V. amygdalina (Delile) against P. knowlesi. The fresh leaves of V. amygdalina were sequentially extracted in three solvents, dichloromethane (DCM), methanol (MeOH) and water (H₂O) to attain the crude extracts. Schizont maturation inhibition assays were performed using in vitro P. knowlesi culture (A1H1) to evaluate the anti-plasmodial activities. The in vitro cytotoxicity of the plant extracts was also evaluated with Vero cell line using MTT assay. Plant extracts in all solvents showed good to moderate anti-plasmodial activity against P. knowlesi, with concentration of drug required for 50% growth inhibition (IC₅₀) of 1.356 ± 0.23 μg/mL, 1.131 ± 0.16 μg/mL and 1.973 ± 0.30 μg/mL for DCM, MeOH and H2O extracts, respectively. The concentration of drug that is cytotoxic to 50% cell populations (CC₅₀) for each extract is DCM = 48.61 ± 0.64 µg/mL, MeOH = 63.73 ± 0.78 µg/mL and H₂O = 86.91 ± 1.03 µg/mL, indicating the MeOH and H2O extracts were likely non-toxic to the mammalian cells. In the present study, all crude extracts exhibited Selectivity Index (SI) values above 10, with MeOH extract having the highest selectivity towards malaria parasites. These findings suggest that the extracts of V. amygdalina leaves exhibit anti-plasmodial properties against P. knowlesi even in the crude form and may be a potential candidate for the development of new antiplasmodial drug. This provides scientific evidence for usage of this plant in traditional medicine, and further studies are needed for identification and purification of the active metabolites.

Streptomyces sp. KSF103 has demonstrated promising insecticidal properties, prompting a subsequent study to evaluate the in vitro effects of its ethyl acetate (EA) extract on dengue virus type 2 (DENV-2) replication in Aedes albopictus C6/36 cells. Pre- and post-treatment assays revealed significant inhibition of viral replication, indicating that the EA extract disrupts both viral entry and adsorption in pre-treated cells, as well as intracellular replication in post-treated cells. Chemical profiling using liquid chromatography-mass spectrometry (LC-MS) identified several bioactive compounds in the extract, including pentanamide, C17 sphinganine, dichamanetin, dodemorph, and antillatoxin B. Further in silico molecular docking analysis targeting DENV-2 NS2B/NS3 protease, NS5 polymerase, and envelope (E) protein revealed that antillatoxin B and dichamanetin exhibit strong binding affinities, supporting their potential antiviral activity. These findings align with the observed inhibitory effects of the EA extract and highlight its potential as a source of potent DENV-2 inhibitors.

The increasing prevalence of mosquito-borne diseases such as dengue fever necessitates the development of effective and safe repellents. This study evaluated the repellent efficacy of Coleus amboinicus essential oil (CAEO) against Aedes aegypti, a primary vector of dengue in Malaysia. Essential oil was extracted via hydrodistillation and analyzed using GC-MS, revealing 17 compounds, with carbamic acid (30.75%) as the major constituent, followed by caryophyllene (6.52%) and ρ-cymene (6.40%). Repellency assays were conducted using human volunteers at concentrations of 2.5%, 5.0%, 10.0%, and 20.0% CAEO and DEET. Results indicated that CAEO exhibited a concentration-dependent repellent effect comparable to DEET, with 20% CAEO offering 95.83% repellency. Complete protection time evaluation showed CAEO provided 100% protection for 30 minutes and >80% efficacy for up to 3.5 hours, while DEET offered complete protection for 4 hours. The findings highlight CAEO's potential as a natural repellent alternative, although variability in composition and efficacy underscores the need for further research, including field trials and formulation enhancements to improve longevity and effectiveness.

This study evaluated soil-transmitted helminth (STH) infections among the Kensiu Negrito indigenous community in Kampung Lubuk Legong, Kedah, Malaysia, before and after the COVID-19 pandemic. A total of 70 and 87 participants were examined in 2020 and 2022, respectively. STH infections were detected using the Kato-Katz and formalin-ether concentration methods. The overall prevalence declined from 85.7% in 2020 to 65.5% in 2022, a statistically significant reduction (p = 0.0054). Trichuris trichiura remained the most common STH infection (year 2020: 84.3%; year 2022: 63.2%), followed by Ascaris lumbricoides (2020: 32.9%; 2022: 24.1%) and hookworm (2020: 21.4%; 2022: 25.3%). A statistically significant decrease was observed for T. trichiura overall (p = 0.0039) and in moderate infections (p < 0.0001), while the changes in A. lumbricoides and hookworm were not significant. The study employed a descriptive design and statistical comparisons were limited due to the small sample size. Despite this, the findings suggest an overall improvement in STH prevalence post-pandemic. Continued monitoring and culturally sensitive interventions remain essential to address persistent infection and promote long-term health improvements in Orang Asli communities.

The presence of chemical substances can interfere with the insect activities, affecting the decomposition duration of carrion, thus under-estimating the minimum post-mortem interval. This study investigates the effects of coumarin an active ingredient in anti-coagulant rodenticide, on carrion decomposition and secondary bioaccumulation in fly larvae tissue. Twenty-four rat carcasses were divided into control (CR) and coumarin-treated (TR) groups, and their decomposition stages were observed under identical environmental conditions. Results indicate that coumarin delayed the decomposition by approximately four days, primarily due to its impact on insect arrival and larval activity. Chrysomya rufifacies (Macquart, 1843) (Diptera: Calliphoridae) was the predominant species in both groups, with slower larval feeding on TR carcasses prolonging the transition from active to advanced decay. Secondary bioaccumulation of coumarin in third-instar larvae was detected using Gas Chromatography-Mass Spectrometry (GC-MS). These findings highlight coumarin's potential to alter insect succession patterns and its implications for minimum post-mortem interval (minPMI) estimation in forensic investigations.

The Kinabatangan Wildlife Sanctuary is internationally known for its biodiversity and is recognized as one of an Important Bird Area (IBA). There are eight species of hornbills that persist in the fragmented landscape of Kinabatangan, Sabah. While the lack of nesting sites, food resources and hunting threats have been well described, little is known about the health status of these birds in the wild. Accordingly, the present study aimed to determine the occurrence of Cryptosporidium and Giardia genotypes in the wild populations of hornbills in Sabah, East Malaysia as it may have implications to current conservation strategies. Understanding the distribution of parasites in wildlife is a crucial area of study, as parasites can have a substantial impact on the health and viability of wild animals, as well as zoonotic consequences. At the time of writing, the occurrence of Cryptosporidium and Giardia protozoa in wildlife has been understudied and poorly documented in Southeast Asia. This study provides the first molecular evidence of zoonotic Giardia duodenalis assemblages A and B in hornbills. These findings are important to assess the health of wild populations of endangered hornbills. In addition, to emphasize the importance of monitoring the distribution of assemblages of G. duodenalis with a broad host distribution as top priority for the development of appropriate public health policies to reduce the potential transmission of this enteric protozoan.