Tropical biomedicine最新文献

The community that progressively colonizes a decaying corpse can be considered a small ecosystem mostly composed of sarcosaprophagous arthropods belonging to the orders Diptera and Coleoptera. Studies on these species are often performed through animal models to obtain data on their succession, behaviour and life cycle, together with information on habitat, corpse conditions, season and association with other species. These data may be relevant for forensic investigations, especially concerning the estimation of Post Mortem Interval (PMI). An investigation on the sarcosaprophagous insect community in a rural area was set in Calabria (Southern Italy), using a pig, Sus scrofa Linnaeus, 1758 (Artiodactyla: Suidae) as experimental model. Analyses of the community of Diptera and Coleoptera revealed the massive presence of Necrodes littoralis (Linnaeus, 1758) (Coleoptera: Silphidae). Adults of this species reached the carcass during the bloated stage and a large amount of larvae was detected from the decay stage onwards, simultaneous to the sharp decrease in dipteran larvae and pupae. The occurrence and the activity of N. littoralis should be considered to avoid misinterpretation and errors in estimating PMI in forensic investigation.

Chrysomya megacephala larvae can easily be identified using cheap traditional microscopy techniques. Nevertheless, identification using taxonomy keys may be hampered, if the morphological characteristics of the larvae are incomplete, or immature for microscopic identification. To overcome the difficulty of species determination, molecular identification has gained relevance and is applied in forensic investigations. This study aimed to identify a novel target gene, known as the gustatory receptor 1 gene (CmegGr1), which has never been used for identification. The third instar larvae of Ch. megacephala (n = 30) and eight other forensically important fly species were obtained from two sources; rabbit carcasses and the Forensic Entomology Unit collection. Their DNAs were extracted and the CmegGr1 gene was amplified using polymerase chain reaction (PCR). The resulting sequences were subjected to phylogenetic analysis. A 209 bp fragment of the CmegGr1 gene was successfully amplified in 80% (24/30) of Ch. megacephala samples, while all of the non-Ch. megacephala species were not amplified. The phylogenetic analysis revealed that the evolutionary tree of CmegGr1 shares many traits with the 21a gustatory receptors of Calliphora stygia and Lucilia cuprina (Gr21a), which are also classified as necrophagous fly species. The high specificity of species identification was demonstrated in the present study using DNA barcoding, which led to the conclusion that the CmegGr1 gene could serve as an alternative marker for identifying Ch. megacephala.

Cytoform C, one of three cytoforms in the Simulium angulistylum Takaoka & Davies complex from a high mountain in northeastern Thailand was morphologically and molecularly investigated. All known life stages (larva, pupa, adult male and female except egg) were morphologically similar to, but distinguishable from S. angulistylum s. str. and S. isanense Takaoka, Srisuka & Saeung in the adults by the relative length of the fore and hind basitarsi and relative length of the tooth to the claw. It is also morphologically distinct from other species of the S. epistum species-group. Here, it is formally described as a new species, S. prayooki. Molecular genetic data based on mitochondrial cytochrome c oxidase subunit I (COI) also supported the morphological similarity between the new species and the two related known species (S. angulistylum s. str. and S. isanense) as phylogenetic analysis retrieved them all from a single clade and with a low level of interspecific genetic divergence (1.74%). This might possibly have resulted from incomplete lineage sorting as they are likely to share a recent common ancestor. Despite limitation of molecular genetic differentiation, the new species was distinctly different from two other cytoforms of S. angulistylum complex based on polytene chromosome banding patterns and ecology of the immature stages. Thus, this study highlights the necessity of using an integrated approach for fully understanding black fly biodiversity.

Birds are known to be the most mobile hosts and are therefore considered to be hosts with potential to contribute to the long-distance spread and transmission of tick-borne pathogens. In the present study, ticks were collected from a hornbill nest at Chaiyaphum Province, Thailand. They were screened for the presence of Coxiella bacteria using conventional PCR. The evolutionary relationships of positive Coxiella-like bacteria (CLB) were analysed based on the gene sequences of 16S rRNA, groEL and rpoB. Among all 22 tested ticks, CLB infections were found in 2 Haemaphysalis wellingtoni individuals. In a phylogenetic analysis, the Coxiella 16S rRNA gene detected in this study formed a separate clade from sequences found in ticks of the same genus. In contrast, the phylogenetic relationships based on groEL and rpoB revealed that these two genes from H. wellingtoni ticks grouped with CLB from the same tick genus (Haemaphysalis). This study is the first to report the presence of CLB in H. wellingtoni ticks associated with the Great Hornbill, Buceros bicornis in Thailand. Three genes of CLB studied herein were grouped separately with Coxiella burnetii (pathogenic strain). The effects of CLB in the ticks and Buceros bicornis require further investigation.

Pathogenic free-living amoebae (FLA), namely Acanthamoeba sp., Naegleria fowleri and Balamuthia mandrillaris are distributed worldwide. These neurotropic amoebae can cause fatal central nervous system (CNS) infections in humans. This review deals with the demographic characteristics, symptoms, diagnosis, and treatment outcomes of patients with CNS infections caused by FLA documented in India. There have been 42, 25, and 4 case reports of Acanthamoeba granulomatous amoebic encephalitis (GAE), N. fowleri primary amoebic meningoencephalitis (PAM), and B. mandrillaris meningoencephalitis (BAE), respectively. Overall, 17% of Acanthamoeba GAE patients and one of the four BAE patients had some form of immunosuppression, and more than half of the N. fowleri PAM cases had history of exposure to freshwater. Acanthamoeba GAE, PAM, and BAE were most commonly seen in males. Fever, headache, vomiting, seizures, and altered sensorium appear to be common symptoms in these patients. Some patients showed multiple lesions with edema, exudates or hydrocephalus in their brain CT/MRI. The cerebrospinal fluid (CSF) of these patients showed elevated protein and WBC levels. Direct microscopy of CSF was positive for amoebic trophozoites in 69% of Acanthamoeba GAE and 96% of PAM patients. One-fourth of the Acanthamoeba GAE and all the BAE patients were diagnosed only by histopathology following autopsy/biopsy samples. Twenty-one Acanthamoeba GAE survivors were treated with cotrimoxazole, rifampicin, and ketoconazole/amphotericin B, and all eleven PAM survivors were treated with amphotericin B alongside other drugs. A thorough search for these organisms in CNS samples is necessary to develop optimum treatment strategies.

Plants are alternative source of natural medicines due to secondary active metabolites. Fagonia cretica extracts and Gradient High-Pressure Liquid Chromatography fractionations were checked against multidrug-resistant gastrointestinal pathogens including, Salmonella typhi, Escherichia coli and Shigella flexneri. ESI-MS/MS analysis of bioactive HPLC fractions was performed to elucidate antibacterial compounds. F. cretica extracts exhibited potential antibacterial activity. Twenty-four (24) HPLC fractions were obtained from methanol, ethanol and aqueous extracts of F. cretica. Eighteen (18) fractions showed antibacterial activity, while no activity was observed by the remaining six (6) fractions. HPLC fractions, F1 (25^g ± 0.20 mm) and F2 (15^f ± 0.12 mm) of aqueous extract exhibited activity against multidrug resistant GI pathogens. Gallic acid, quinic acid, cyclo-l-leu-l-pro, vidalenolone, liquirtigenin, rosmarinic acid and cerebronic acid were identified in F1 fraction of aqueous extract, while succinic acid, cyclo (l-Leul-Pro) and liquirtigenin were identified in F2 fraction of aqueous extract through ESI-MS/MS analysis. F. cretica extracts and HPLC fractions showed potential activity against MDR GI pathogens. Vidalenolone, Cyclo-1-leu-1-pro and Cerebronic acid are first time reported in F. cretica. Further characterization of bioactive compounds from F. cretica may be helpful to elucidate antibacterial therapeutic molecules.

Cestode infections is widely reported in rodents, however species identification remains problematic due to the genetic or interspecies variation. Therefore, this study was aimed to verify the Cyclophyllidean parasites recovered from wild rats captured from different forest types using molecular based methods. Maximum-likelihood (ML) and neighbour-joining (NJ) trees were constructed inferred from 18 small subunit nuclear ribosomal RNA gene (18SrDNA) and mitochondrial cytochrome c oxidase subunit one gene (COX1) sequences of cestode worms recovered from 124 individuals from four rat species. Sequences obtained from both Hymenolepis diminuta and Hydatigera parva represents the first records in Malaysia. All the sequences were successfully amplified with product with total length of 205 and 1202 base pairs (bp), respectively. Three cestode species from the Family Hymenolepididae (Hymenolepis diminuta) and Family Taeniidae (Hydatigera parva; Hydatigera taeniaeformis) were successfully characterized using phylogenetic analyses and haplotype networking. Phylogenetic analysis showed that H. diminuta, Hydatigera parva (Hy. parva) and Hydatigera taeniaeformis (Hy. taeniaeformis) formed its own monophyletic clade in 18SrDNA analyses. Results also showed that Hy. taeniaeformis shared the same haplotype group with Hy. taeniaeformis from China (COX1) and linked with Hy. taeniaeformis from Japan (18SrDNA) while the Malaysian H. diminuta clearly formed a separate haplotype and networked with other regions. The Malaysian Hy. parva isolation, on the other hand, appeared to be genetically distinct from the European Hy. parva (Spain) strain, but closely linked to the local isolates. Molecular methods employed successfully improved in the detection of complex species in this group. The findings showed that molecular data can be useful to deeply study intra-specific variation in other cestode worms.

Coronavirus Disease 2019 (COVID-19) pandemic has become a global concern. Recently, Indonesia contributed the third-highest number of new COVID-19 cases in the world. We provide supporting information for COVID-19 management. This retrospective cohort study was conducted at Dr. Soetomo General Hospital. Researchers collected demographics, comorbidity, initial laboratory tests, and complications data of patients. This study performed a comparative, survival, and Receiver Operating Characteristic (ROC) curve analysis. Survival analysis showed a decrease in the probability of survival associated with an increase in the variables of age, diabetes, white blood cell (WBC) count, and neutrophils percentage, and a decrease in lymphocytes percentage during hospitalization. Lymphocyte percentage, neutrophil-lymphocyte ratio (NLR), WBC count, neutrophil percentage, had an accuracy 0.727 (95%CI 0.642-0.812; p<0.001), 0.726 (95%CI 0.641-0.812; p<0.001), 0.706 (95%CI 0.615-0.796; p<0.001), and 0.700 (95%CI 0.612-0.788; p<0.001) respectively, in predicting worse outcome. Our study suggests routine complete blood count tests in the admission of a patient with COVID-19 infections, which can be used to determine the survival and prognosis of hospitalized patients.

This is the first documentation of parasitic mite, Leptus sp., found on a necrophagous blowfly, Chrysomya villeneuvi collected from a decomposing wild boar carcass placed in Taman Negara (National Park), Kuala Keniam, Pahang, Malaysia. Blowflies around the carcass were captured using an insect net before being examined under a stereomicroscope. Upon microscopic observation, we found a mite attached on the scutellum of C. villeneuvi adult. The mite was carefully removed and preserved in 70% ethanol subsequently. Then, the mite was cleared in lactophenol before being mounted in Hoyer's medium. The morphological identification of the mite was conducted and Leptus sp. was identified. The species belongs to the phalangii species group and the aldonae species subgroup. This study highlights the new association of Leptus sp. and C. villeneuvi for the first time.

Circumsporozoite protein (CSP) is a sporozoite major surface protein of Plasmodium species. The protein showed promising protection level as a vaccine candidate against Plasmodium falciparum infection. There is a lack of studies on P. knowlesi CSP (PkCSP) as a vaccine candidate due to the high polymorphic characteristic of central repeat region. Recent studies showed the protein has a relatively conserved region at the C-terminal, which consists of T- and B-cell epitopes. This could be the target region for vaccine development against the pre-erythrocytic stage of the parasite. In this study, recombinant PkCSP was expressed using Escherichia coli system. Recombinant PkCSP was immunized in animal models and the antiserum was evaluated using immunoblot analysis. Results showed that PkCSP can be successfully expressed using the bacterial system. Endpoint titre of the antiserum were ranged up to 1:819200. Immunoblot analysis showed the antiserum recognized recombinant PkCSP but not total protein extract from P. knowlesi erythrocytic stage. In conclusion, PkCSP could elicit strong immune response in animal models. However, serum antibodies could not recognize protein from the parasite's erythrocytic stage extract indicating it is not expressed at the erythrocytic stage. Therefore, PkCSP remains as a potential pre-erythrocytic vaccine candidate against P. knowlesi infection.