Tropical biomedicine最新文献

Nipah virus (NiV), a highly pathogenic henipavirus of the family Paramyxoviridae, which causes fatal encephalitis in 40-70% of affected patients, was first reported in Malaysia over 20 years ago. Pteropid bats are the natural hosts of henipaviruses, and ticks have been proposed as a possible link between bats and mammalian hosts. To investigate this hypothesis, infection of the tick cell line IDE8 with NiV was examined. Presence of viral RNA and antigen in the NiV-infected tick cells was confirmed. Infectious virions were recovered from NiV-infected tick cells and ultrastructural features of NiV were observed by electron microscopy. These results suggest that ticks could support NiV infection, potentially playing a role in transmission.

Blow flies, flesh flies, and house flies can provide excellent evidence for forensic entomologists and are also essential to the fields of public health, medicine, and animal health. In all questions, the correct identification of fly species is an important initial step. The usual methods based on morphology or even molecular approaches can reach their limits here, especially when dealing with larger numbers of specimens. Since machine learning already plays a major role in many areas of daily life, such as education, business, industry, science, and medicine, applications for the classification of insects have been reported. Here, we applied the decision tree method with wing morphometric data to construct a model for discriminating flies of three families [Calliphoridae, Sarcophagidae, Muscidae] and seven species [Chrysomya megacephala (Fabricius), Chrysomya rufifacies (Macquart), Chrysomya (Ceylonomyia) nigripes Aubertin, Lucilia cuprina (Wiedemann), Hemipyrellia ligurriens (Wiedemann), Musca domestica Linneaus, and Parasarcophaga (Liosarcophaga) dux Thomson]. One hundred percent overall accuracy was obtained at a family level, followed by 83.33% at a species level. The results of this study suggest that non-experts might utilize this identification tool. However, more species and also samples per specimens should be studied to create a model that can be applied to the different fly species in Thailand.

The estimation of the postmortem interval (PMI) is an essential information in death investigations. It is necessary to know the developmental data of the most important necrophagous insect species in every geographical area. Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) is one of the most common species associated with human body decomposition, especially in the tropics, so a precise knowledge of its life cycle is crucial. However, despite its ubiquity, developmental data in a range of tropical temperatures is scarce. For this reason, the aim of this study is to provide the developmental data of the blowfly, C. megacephala, in a range of tropical temperatures and to apply these data in forensic entomology. Four temperatures were examined (i.e., 27.0°C 29.5°C, 32.0°C and 34.5°C) and the time of developments from egg to adult were recorded. To build the growth curves, five larvae per day were measured with a digital caliper. Accumulated degree-days were calculated and the isomorphen diagram for this species was plotted. As we predicted, the results showed that the life cycle of this species was affected by the increasing temperature. The implications of these new data for determining the minimum PMI in forensic entomology were discussed.

Over the last decades, the epidemiology of human brucellosis globally has been subjected to significant changes, with the eradication of many existing endemic hot spots. This paper describes three cases with initial misdiagnosis of brucellosis that were managed during 2011-2017 in Republic of North Macedonia, country that until recently has been declared as endemic region. In spite of the fever, constitutional symptoms, focal disease (spondylitis, pneumonia and orchitis) and previous contact with domestic animals, brucellosis was not initially recognized, and patients were inadequately managed. Brucellosis should be part of differential diagnostic considerations in patients exposed to contacts with animals, with osteoarticular symptoms and signs, constitutional manifestations and different organ involvements in endemic regions where its incidence is diminishing.

Antimicrobial resistance (AMR) is a global health crisis. Despite the drug discovery efforts, AMR is increasing, and discoveries are nearly nil. It is thus critical to design new strategies. Probiotics are tapped as alternatives to antibiotics for the treatment of gut-associated diseases. Lactobacillus species, common in food products, can inhibit the growth of gut pathogens. Here, we demonstrate the antimicrobial activities of Lactobacillus species - Lactobacillus paracasei, Lactobacillus casei, and Lactobacillus delbrueckii subsp. bulgaricus are enhanced when cocultured with Salmonella enterica subsp. enterica serovar Typhimurium. Cell-free culture supernatants (CFCS) from cocultures of Lactobacillus spp. and Salmonella enterica serovar Typhimurium more potently inhibit pathogen growth than their monoculture counterparts. Interestingly, we discovered that Salmonella enterica serovar Typhimurium could enhance the production of antimicrobials from Lactobacillus spp., most evident in L. delbrueckii subsp. bulgaricus. Also, L. delbrueckii subsp. bulgaricus CFCS upregulates key Salmonella virulence genes, hilA and sipA. Whether this increases Salmonella's pathogenicity in vivo or reduces pathogen fitness and growth inhibition in vitro warrants further investigation. We propose that these probiotic isolates may be utilized for innovative natural food processing and preservation strategies to control Salmonella food contaminations. Importantly, our findings that Salmonella elicits an enhanced antimicrobial activity from Lactobacillus spp. provide evidence of a pathogen-mediated elicitation of antimicrobial production. Therefore, extending this phenomenon to other microbial interactions may help augment the strategies for drug discovery.

Circumsporozoite protein (CSP) central repeat region is one of the main target regions of the RTS,S/AS01 vaccine for falciparum infection as it consists of immunodominant B cell epitopes. However, there is a lack of study for P. knowlesi CSP central repeat region. This study aims to characterise the CSP repeat motifs of P. knowlesi isolates in Peninsular Malaysia. CSP repeat motifs of 64 P. knowlesi isolates were identified using Rapid Automatic Detection and Alignment of Repeats (RADAR). Antigenicity of the repeat motifs and linear B cell epitopes were predicted using VaxiJen 2.0, BepiPred-2.0 and BCPred, respectively. A total of 35 dominant repeat motifs were identified. The repeat motif "AGQPQAQGDGANAGQPQAQGDGAN" has the highest repeat frequency (n=15) and antigenicity index of 1.7986. All the repeat regions were predicted as B cell epitopes. In silico approaches revealed that all repeat motifs were antigenic and consisted of B cell epitopes which could be designed as knowlesi malaria vaccine.

Haemonchus contortus (Hc) is a hematophagous parasite affecting the health and productivity of flocks. The administration of chemical anthelmintic drugs (AH) is the common method of deworming; however, generates resistance in the parasites to AH and it is a public health risk due to drug residues in milk, meat and sub-products. Natural compounds from plants are explored to diminish this parasitosis, improving their health and productivity, without the negative effects of AH. Ipomoea genus is a group of climbing plants belonging to the Convulvulaceae family possessing perennial leaves and tuberous roots. Medicinal properties has been attributed to this plant including nutritional agents, emetics, diuretics, diaphoretics, purgatives and pesticides. The objective of this study was assessing the in vitro nematocidal activity of a hydroalcoholic extract (HA-E) obtained from Ipomoea pauciflora (Cazahuate) flowers against Hc infective larvae (L3) and to identify its phytochemical profile (PhC-P). The assay was carried out using microtiter plates (MTP). Four HA-E concentrations were assessed and Ivermectin and distilled water were used as positive and negative control groups, respectively. Approximately 100 Hc L3 were deposited in each well (n=12) and incubated at 25-35°C for 7 days. Data were analyzed using ANOVA and a General Linear Model (GLM) followed by Tukey test (P<0.05). The treatments showing a concentration-dependent effect (CDE) were analyzed to identify their 50% and 90% lethal concentrations (CL50, 90) via a Probit Analysis. The highest mortality was observed at 50 mg/mL (82.64 ± 0.71%) and the lowest at 6.25 mg/mL (56.46 ± 2.49%), showing a CDE with increasing mortality from 6.25 to 50 mg/mL. The PhC-P revealed the presence of alkaloids, coumarins, flavonoids, tannins and triterpenes/ sterols. A HA-E from flowers of I. pauciflora will be considered to assess its potential use in the control of haemonchosis in small ruminants.

Anaplasma marginale is the most prevalent tick-borne haemoparasite of cattle and causes huge economic losses to the dairy industry worldwide. This study aimed to determine the occurrence of A. marginale infection in blood and tick samples collected from livestock animals in the districts located in Khyber Pakhtunkhwa (KPK), Pakistan. A total of 184 blood and 370 tick samples were included in this study. It has never been reported that sheep, goats, and cattle in Tank, Ghulam Khan, Birmil and Miran Shah areas were infected with A. marginale. All samples of blood and ticks were collected through random sampling from March 2021 to January 2022 from cattle, sheep and goats and screened through PCR for anaplasmosis by using primer pairs of Anaplasma spp. Three hundred and seventy ticks were collected from infested hosts (120/184, 64.21%). Among the four morphologically identified tick species, the highest occurrence was recorded for Rhipicephalus sanguineus (n=138, 37.29%), followed by Rhipicephalus microplus (n=131, 35.4%), Rhipicephalus annulatus (n=40, 10.81%), Hyalomma anatolicum (n=31, 8.37%), and Hyalomma marginatum (n=30, 8.1%). The occurrence of female tick was highest (n=160, 43.24%), followed by nymphs (n=140, 37.38%) and males ticks (n=70, 18.9%). Among these ticks, A. marginale was detected in female ticks of R. microplus, and R. sanguineus. Molecular identification of A. marginale was confirmed in 120 out of 184 blood samples and 6 out of 74 tick samples. Overall, occurrence of A. marginale in blood and tick samples was found to be 65.21% and 8.1% respectively. Species-wise occurrence in blood samples of goats were 71.11% followed by sheep 68.31% and cattle 50%. Specie-wise occurrence of A. marginale in tick samples of cattle were 12.5% followed by goats 6.89%. The obtained sequence showed similarity with A. marginale reported from Kenya and USA. We report the first PCR based detection of A. marginale infection in blood samples and in R. sanguineus ticks of goats simultaneously.

Toxoplasma gondii, the etiologic agent of toxoplasmosis, infects about 30 - 50% of the world population. The currently available anti-Toxoplasma agents have serious limitations. The present study aimed to investigate the effects of two antimalarials; buparvaquone (BPQ) and chloroquine (CQ), on immunocompromised mice with chronic cerebral toxoplasmosis, using spiramycin as a reference drug. The assessed parameters included the estimation of mortality rates (MR) among mice of the different study groups, in addition to the examination of the ultrastructural changes in the brain tissues by transmission electron microscopy. The results showed that only CQ treatment could decrease the MR significantly with zero deaths, while both spiramycin and BPQ caused an insignificant reduction of MR compared to the infected non-treated group. All the used drugs decreased the number of mature ruptured cysts significantly compared to the infected non-treated group, while only CQ increased the number of atrophic and necrotic cysts significantly. Furthermore, both spiramycin and BPQ improved the microvasculopathy and neurodegeneration accompanying the infection with different degrees of reactive astrocytosis and neuronal damage with the best results regarding the repair of the microvascular damage with less active glial cells, and normal neurons in the CQ-treated group. In conclusion, this study sheds light on CQ and its excellent impact on treating chronic cerebral toxoplasmosis in an immunocompromised mouse model.