Tropical biomedicine最新文献

{"title":"Molecular evidence of knockdown resistance (kdr) mutations in the head lice (Pediculus humanus capitis) collected from disadvantaged children in Klang Valley, Malaysia.","authors":"A S Mokhtar, N A H Norza, A Zahanuddin, N Sahimin, Y L Lau","doi":"10.47665/tb.42.4.009","DOIUrl":"10.47665/tb.42.4.009","url":null,"abstract":"<p><p>Pediculosis capitis, caused by infestation of the human head louse Pediculus humanus capitis is endemic all over the world, and Malaysia is no exception. Permethrin is recommended as one of the first-line treatments for pediculosis capitis. However, after decades of intensive and continuous use, numerous treatment failures and recurrent cases have been reported globally due to established evidence of permethrin resistance. The fact that permethrin-based products are still widely used and available over the counter prompted this study to investigate the genotypic basis of permethrin resistance and to identify kdr alleles in head lice collected from seven children shelters located across Klang Valley, Malaysia. The PCR-RFLP employed in this study successfully demonstrated the kdr T917I mutation in head lice resulting in two genotypes: 31 (49.21%) homozygous susceptible (SS) and 32 (50.79%) heterozygous resistant (RS). These findings provide baseline data on permethrin resistance in Malaysia, which has not been previously investigated.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"430-434"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Taenia saginata Infection in a 25-Year-Old Immigrant in Malaysia: A Case Study.","authors":"K K Lim, J P Karshini, M Y Lai, Y L Lau, T J Tee","doi":"10.47665/tb.42.4.003","DOIUrl":"10.47665/tb.42.4.003","url":null,"abstract":"<p><p>Taeniasis is a parasitic infection in humans by tapeworm species typically acquired through the ingestion of undercooked pork or beef leading to infections with Taenia solium, Taenia asiatica or Taenia saginata. We reported a case of taeniasis in a young man of Chinese nationality who presented with recurrent episodes of expelling proglottids. He was at risk due to his preference for consuming undercooked beef. He remained asymptomatic and his physical examination was unremarkable. A 330 cm tapeworm was recovered; each mature proglottid contained 12-30 primary lateral uterine branches. Stool examination revealed eggs consistent with Taenia species. DNA sequencing from the isolate confirmed the identification of T. saginata.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"379-383"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Rinconada Lake System (RLS) as a Potential Reservoir of Protozoan Parasites in Camarines Sur, Philippines.","authors":"J M Q Paet, S M Rojas, J F Torres","doi":"10.47665/tb.42.4.001","DOIUrl":"10.47665/tb.42.4.001","url":null,"abstract":"<p><p>Protozoan and helminthic parasitism remain significant health and economic burdens, particularly in developing countries such as the Philippines. This study evaluated the Rinconada Lake System (RLS) in Camarines Sur, comprising Lakes Buhi, Bato, and Baao, as a potential reservoir for medically important parasites. Microscopic examination of surface water samples from 20 stations revealed no helminthic ova, which may have settled in sediments, but detected potential coccidian oocysts of Cryptosporidium spp. (55%, 11/20) and Cyclospora sp. (40%, 8/20). Culture-based detection of free-living amoeba was at 60% (36/60), showing organisms resembling Acanthamoeba spp. (35% or 21/60) significantly linked to Lake Baao and Lake Bato (P < 0.01) likely reflecting greater anthropogenic influence. The metabarcoding confirmed the presence of protozoan parasites in the lakes, such as Echinamoeba sp. and Vermamoeba vermiformis, while no helminthic parasites were detected using current methods. Additional microbial eukaryotes of medical relevance, such as fungi and algae, were also identified. Retrospective analysis of the available health records from surrounding communities showed that Entamoeba histolytica was the most documented case for 4 years (47.8% or 75/157), followed by various helminthic infections (49.7% or 78/157), predominantly caused by Ascaris lumbriocoides. There was no significant association with the patient's residence or sex, except for significantly higher cases in those aged 0-10 years. In conclusion, findings suggest that the RLS may serve as an environmental reservoir for opportunistic protozoan parasites, while its role in helminthic transmission requires further investigation. Based on current evidence, emphasis on surveillance and mitigation strategies in communities surrounding the RLS, especially for protozoan parasites, is highly recommended.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"361-369"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular surveillance of insecticide resistance: High frequency of kdr mutations in permethrin-exposed Aedes mosquitoes from Kuala Lumpur and Selangor, Malaysia.","authors":"N S N Saiful Anuar, F Izzat, Z Rahman, I A Salim, I H Ishak, O Q Junaid, F W Cheong, R Ravi","doi":"10.47665/tb.42.4.006","DOIUrl":"10.47665/tb.42.4.006","url":null,"abstract":"<p><p>Despite ongoing vector control programs, dengue incidence in Malaysia continues to rise. A significant contributing factor is the emergence of insecticide resistance in Aedes mosquitoes, particularly against pyrethroids such as permethrin. This study aimed to evaluate permethrin resistance in Aedes aegypti and Aedes albopictus from Kuala Lumpur and Selangor and to investigate the prevalence of knockdown resistance (kdr) mutations in the voltage-gated sodium channel (Vgsc) gene. Due to limited sample quantity and quality, molecular assessment of kdr mutations was performed only for Ae. aegypti. Ovitraps were deployed in three dengue hotspot areas to collect Aedes eggs. Eggs were reared to adulthood under controlled laboratory conditions. Adult female mosquitoes were subjected to the WHO tube bioassay using permethrin to assess phenotypic resistance. Genomic DNA was extracted from individual Ae. aegypti, and polymerase chain reaction (PCR) was conducted to amplify target regions of the Vgsc gene using published kdr-associated primers. Direct sequencing of PCR products was performed to identify point mutations associated with pyrethroid resistance. Both Ae. aegypti and Ae. albopictus populations showed high levels of permethrin resistance, with mortality rates of <5% and <50%, respectively, indicating confirmed resistance. Sequencing of Ae. aegypti revealed the presence of pyrethroid resistance-associated kdr mutations, including S989P, A1007G, V1016G, and F1534C. These findings suggest strong selective pressure on local Ae. aegypti populations, reflecting ongoing adaptation to insecticidal interventions. The identification of these mutations emphasizes the challenges faced by current vector control strategies relying predominantly on chemical control.The detection of both phenotypic permethrin resistance and kdr mutations in Ae. aegypti populations from Kuala Lumpur and Selangor highlights the urgent need to revise and diversify vector control strategies. Improved sampling and molecular surveillance of Ae. albopictus are recommended to provide a more comprehensive understanding of insecticide resistance dynamics in Malaysian dengue vectors.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"408-414"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Four new species of black flies (Diptera: Simuliidae) from Sumatra, Indonesia.","authors":"H Takaoka","doi":"10.47665/tb.42.4.005","DOIUrl":"10.47665/tb.42.4.005","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"391-407"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic diversity, microbiome composition and socio-sanitary predictors of head lice (Pediculus humanus capitis) among disadvantaged children in Klang Valley, Malaysia.","authors":"A Zahanuddin, F F Rahim, Y L Lau, A S Mokhtar","doi":"10.47665/tb.42.4.010","DOIUrl":"10.47665/tb.42.4.010","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"435-445"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing ovitrap design: the role of ovistrip texture, colour, and water in modulating oviposition behavior of Aedes vector mosquitoes.","authors":"A P S Perera, K O Bandaranayaka, M M S M B Marasinghe, S N Weerakoon, H T R Jayasooriya","doi":"10.47665/tb.42.4.012","DOIUrl":"10.47665/tb.42.4.012","url":null,"abstract":"<p><p>Ovitrap surveillance of Aedes vectors in Sri Lanka needs improvement to effectively monitor vector abundance in dengue high-risk areas and detect emerging infestation zones. A study was conducted in two dengue high-risk areas, Narahenpita and Battaramulla in the Western Province, to assess the influence of ovistrip texture, color, and water type on Aedes oviposition, while adhering to WHO guidelines. The relationship of OI and the mean number of eggs per trap with ovitrap designs were determined by General Linear Model (GLM), which revealed a significant difference in the OI between the two study sites (P=0.005), while the mean number of eggs per ovitrap did not differ significantly (P=0.134). Water type had no significant influence on OI and mean number of eggs per ovitraps. A significant effect of ovistrip type (F=6.73, P<0.001) was found on OI and mean egg per trap (F=9.85, P<0.001), where filter paper exhibited the largest coefficient in magnitude (-0.1698), indicating a strong negative correlation with OI and mean eggs per trap (-2.445) while white fabric showed a strong positive co-efficient magnitude with OI (0.1108) and mean egg per trap (1.605). According to Spearman's rank correlation, the rainfall did not have a statistically significant effect on the number of eggs collected or the OI. The study suggested that fabric ovistrips colored white combined with rainwater or tap water, make ovitraps highly effective for Aedes vector surveillance, while the currently used filter paper ovistrip having a negative effect on the egg number laid.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 4","pages":"459-466"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cross sectional epidemiological investigations of human brucellosis in pregnant women of Punjab, Pakistan.","authors":"F Nisar, Z Nawaz, A B Siddique, M A Zahoor, M Khurshid, A Yasmin, S Ali","doi":"10.47665/tb.42.3.009","DOIUrl":"https://doi.org/10.47665/tb.42.3.009","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 3","pages":"307-312"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145319052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High burden of soil-transmitted helminth infections among preschool and school aged-children in North Kodi, Southwest Sumba, Indonesia: A crosssectional study.","authors":"S Ali, F Anggraini, F Kurniawan, H Kristin, A Hengestu, Y K Lede, G Kerans, A A L Jerawu, F S Joprang, M M M Kaisar","doi":"10.47665/tb.42.3.014","DOIUrl":"https://doi.org/10.47665/tb.42.3.014","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 3","pages":"344-355"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145318794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vernonia amygdalina (Delile) exhibits in vitro anti-plasmodial activities against Plasmodium knowlesi.","authors":"N Z Zulkefli, F W Cheong, A Amir, Y L Lau","doi":"10.47665/tb.42.3.002","DOIUrl":"https://doi.org/10.47665/tb.42.3.002","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":101343,"journal":{"name":"Tropical biomedicine","volume":"42 3","pages":"242-249"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145318948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}