Tropical biomedicine最新文献

Reverse transcription-polymerase chain reaction (RT-PCR) cycle threshold (Ct) value in detecting the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is inversely proportionate to the virus load in the patient's specimen. These values could be beneficial in the epidemic trajectory at the population level. The SARS-CoV-2 B.1.617.2 (Delta) variant which emerged in late 2020, caused an unprecedented exponential increase in SARS-CoV-2 infection cases worldwide. In Malaysia, the surge in coronavirus disease 2019 (COVID-19) cases and the inclining positivity rate contributed to the epidemic waves in late May 2021. Sudden surge in cases was suggested to be associated with increased transmission caused by the emergence of the B.1.617.2 variant. In the present study, Ct value distribution of the positive COVID-19 samples from 2020 and 2021 was tabulated against SARS-CoV-2 genomic variants determined from genomic sequencing. A significant decreasing pattern of median Ct values from overall 2020 and 2021 samples was evident (p<0.01). However, notable variability was observed in the Ct values between 2020 and 2021, which samples showing lower median Ct values in 2021. The percentages of SARS-CoV-2 genomic variants B.1.36 and B.1.524 were 31.6% and 68.4%, respectively, for samples obtained in October and December 2020. Whereas samples obtained in June and July 2021 were 100% of the B.1.617.2 variant. The population neutralizing antibody against SARS-CoV-2 during the initial peak of B.1.617.2 was low, however, increased during the B.1.617.2 wave. A decreasing trend in the Ct value distribution from samples tested in our laboratory correlated well with the increasing weekly COVID-19 cases reported by the Malaysia national data, which was subsequently attributed to the emergence of B.1.617.2 variant. This study proposes that analyzing Ct value distribution in screened SARS-CoV-2 samples could reveal population-level transmission dynamics and emerging variants. Coupled with genomic sequencing, it supports early control strategies against new SARS-CoV-2 strains.

Bacteremia due to Granulicatella adiacens has been rarely reported in the medical literature. A middleaged gentleman developed necrotizing fasciitis on his left second toe after stepping on a nail. A ray amputation was performed and ceftazidime-susceptible Pseudomonas aeruginosa was isolated from his bone culture. However, while receiving ceftazidime for the necrotizing fasciitis, his blood culture vial was positive for gram-positive cocci-shaped bacteria in short chains which grew as tiny non-lytic colonies on sheep blood agar only following extended incubation. There was no culture evidence of P. aeruginosa in the same blood specimen. The gram-positive organism was conclusively identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry as G. adiacens. The patient was treated with benzylpenicillin (to which the organism tested susceptible) for 14 days before he was discharged home.

We report three cases of rickettsial infections diagnosed by performing a multiplex molecular syndromic panel, in patients who presented with undifferentiated tropical fever with non-specific clinical signs and symptoms. All three patients were from regions endemic to agents of tropical fever, such as dengue fever, leptospirosis, and typhoid fever, which were considered as differential diagnoses in the initial investigative workup. These cases highlight the need for a rapid syndromic diagnostic approach for tropical fever to enable timely diagnosis and institution of appropriate antibiotic therapy, as the typical empirical antibiotics for undifferentiated febrile illness, targeting the bacterial cell wall are ineffective in treating rickettsial infections.

Salmonellosis is a major bacterial foodborne infection worldwide. Inappropriate usage of drugs, especially antimicrobial usage in animal production, is one of the leading issues of antimicrobial resistance (AMR) in Southeast Asia (SEA) countries, especially in treating Salmonella cases. The AMR issue is critical as antimicrobials have been used indiscriminately for the prevention of diseases and it is threatening food safety, especially in poultry production, which carries the largest group of Salmonella as a natural host. In SEA, the range of resistance for penicillin is 13.3% to 89.5% and for tetracycline, it is 25% to 95.7%. Therefore, to develop prompt interventions, the public health authorities must first be aware and have a complete understanding of Salmonella AMR in poultry settings. This review focuses on insight into the epidemiology of Salmonella and information on the current AMR in poultry chickens, as well as the impact on society. It emphasises the need for collaborative efforts to implement the One Health approach to mitigate the AMR of Salmonella in SEA.

The human liver fluke, Opisthorchis viverrini, is a significant risk factor for cholangiocarcinoma (CCA) in Thailand. Praziquantel (PZQ) is the primary treatment for opisthorchiasis but is associated with adverse effects and the potential development of CCA amid chronic infection and reinfection, prompting the search for alternative treatments. Thunbergia laurifolia is widely used for detoxification from lead poisoning and other toxins. The bioactive compounds of T. laurifolia are categorized into sterols, phenolics, carotenoids, glycosides, and unclassified steroids. It is considered an herb that contains a variety of active compounds, which may demonstrate effectiveness in eliminating parasites. This study evaluated the anthelmintic efficacy of crude extracts of Thunbergia laurifolia on newly excysted juveniles (NEJs) and adult stages of O. viverrini.The experiments were involved treating O. viverrini NEJs and adult worms with various concentrations of the crude extracts (NEJs: 5, 10, 20, 40 mg/ml; adult worms: 20, 30, 40 mg/ml), with PZQ and RPMI-1640 medium serving as positive and negative controls, respectively. An assessment of relative motility (RM) and survival index (SI) was conducted, along with a morphological evaluation using scanning electron microscopy (SEM) and biochemical tests to evaluate the generation of reactive oxygen species (ROS) as a response to stress. Results showed that T. laurifolia crude extract reduced RM and SI of the O. viverrini NEJs and adult worms. SEM revealed minimal tegumental damage when compared to the positive control group. Elevated ROS levels were significantly higher, suggesting oxidative stress as a potential mechanism of action. These findings suggest that T. laurifolia possess promising anthelmintic properties against O. viverrini, meriting further research to isolate active compounds and elucidate their mechanisms. Such studies could lead to the development of novel herbal treatments for opisthorchiasis.

Medicinal plants are an important source of bioactive compounds that have various biological effects on pests and diseases of agricultural and livestock importance. The present study evaluated the nematicidal and insecticidal effects of the acetone extract (E-Ac) of Prosopis laevigata leaves. The tests were carried out under in vitro conditions. E-Ac had 100% nematicidal activity against Haemonchus contortus at 40 and 20 mg/mL, while at 10 mg/mL it had nearly 60% mortality against L₃ H. contortus larvae. When E-Ac was incorporated into an artificial diet, it had an 88% insecticidal effect against Melanaphis sorghi at 72 h at 10 mg/mL. The phytochemical profile of E-Ac revealed the presence of alkaloids, flavonoids, coumarins, tannins, sterols/terpenes and saponins. The results of the present study reveal that E-Ac has secondary metabolites with anthelmintic activity against L₃ larvae of H. contortus and insecticidal activity against adults of M. sorghi, which could represent a viable and affordable allelopathic tool in the control of gastrointestinal nematodiasis in small ruminants and against aphids of agricultural importance.

Canine haemotrophic mycoplasmosis is caused by mycoplasma haemopathogens, which includes Mycoplasma haemocanis (Mhc) and Candidatus Mycoplasma haematoparvum (CMhp). The Mhc and CMhp pose a health risk to dogs, particularly in immunocompromised and splenectomised dogs, as they lead to haemolytic anaemia. There is scarce information on the detection of Mycoplasma in dogs in Malaysia. Therefore, this study aims to detect the presence of Mycoplasma in the blood of shelter and pet dogs and identify associated risk factors in Malaysian dog populations. Blood samples from shelter dogs in Selangor (n = 71) and pet dogs in Johor Bahru (n = 169) were collected. Conventional polymerase chain reaction (PCR) was used to detect Mycoplasma 16S rRNA. Overall, 21.7% of the tested samples were positive, with a higher prevalence among the shelter dogs (45.1%) than pet dogs (11.8%). The Mhc was the predominant species detected, with only one case of CMhp. Risk factors associated with Mycoplasma infection in shelter dogs included urban areas, and the presence of rodents, and wild animals, but no significant associations with tick infestations were detected. These findings necessitate the importance of Mycoplasma transmission dynamics among Malaysian dog populations to assist in the implementation of control measures.

Ticks are obligate hematophagous arachnids that feed on both humans and animals. Despite the extensive research on detection of bacteria in ixodid ticks in Malaysia, there remains limited knowledge about the detection of protozoa in these ectoparasites, especially in those that feed on farm ruminants. In this study, 1,241 ticks belonging to four species (Rhipicephalus microplus, R. haemaphysaloides, Haemaphysalis bispinosa, and H. wellingtoni) were collected from 674 farm ruminants across Peninsular Malaysia. The ticks were pooled and subjected to DNA extraction, followed by protozoal screening using 18S rRNA gene polymerase chain reaction (PCR). Of the 130 tick pools tested, 15 were positive for Babesia (11.54%) and ten for Theileria (7.69%). No Hepatozoon protozoa were detected. All positive pools consisted solely of R. microplus ticks, with no protozoa found in the other three tick species. BLAST analyses revealed that the Babesia sequences were identical to Babesia bigemina, while the Theileria sequences closely resembled Theileria orientalis and Theileria sinensis. This paper presents the first nationwide screening of Babesia, Hepatozoon, and Theileria in ticks infesting farm ruminants from Peninsular Malaysia.

This research aimed to find indigenous plants and suitable solvents to extract substances with the capacity to suppress the immature stages of house fly populations in animal farms and urban areas. Seven native Thai plants were tested: Alstonia scholaris (L.) R.Br., Murraya paniculata (L.) Jack, Citrus aurantium L., Colocasia esculenta (L.) Schott, Limnophila aromatica (Lam.) Merr., Persicaria odorata (Lour.), and Manihot esculenta Crantz. Solvents with different polarities were used in series (hexane, ethyl acetate, acetone, ethanol, and water) to extract the active compounds from the plant tissues. The effects of extracts on immature stage were assessed separately in vitro using a completely randomized design with 5 replicates. The effects of each plant extract on the house fly stages varied depending on the solvent utilized. Extracts with high polarity solvents (ethanol and acetone) showed strong ovicidal activity but for larval and pupal stages, hexane, a low polarity solvent, demonstrated significant larvicidal and pupicidal activity. Acetone and ethanol solvents of P. odorata and L. aromatica caused notable mortality rate for the egg stage. Hexane extracts of M. paniculata and both hexane and ethyl acetate extracts of C. aurantium induced the highest percentage of larval mortality. Even if other plant extracts have less of an impact on the mortality of house fly eggs or larvae, they have an impact on the growth and development. The results showed that most plant extracts based on various solvents caused considerable mortality in house fly pupa. In this study, the hatching percentage of adult females was lower than the adult males after specific plant extracts were applied throughout the larval and pupal phases. High-efficiency plant extracts' LC50 and LC90 values for house fly immature stages were calculated. The acetone extract of P. odorata during the egg stage had LC50 and LC90 values of 7.816 and 31.117 mg/mL, respectively. At the larval stage, M. paniculata's hexane extract had concentrations of 4.865 and 22.284 mg/mL, while C. aurantium's ethly acetate extract had concentrations of 26.424 and 61.801 mg/mL. Significant active chemicals discovered by GC-MS analysis were included bioactive substances with insecticidal properties, including flavonoids, alkanes, coumarins, etc., were identified by GC-MS analysis.

Examining the co-circulation of various serotypes and finding serotypes linked to illness severity were the main objectives of this study, which sought to investigate the epidemiology and serotype distribution of dengue in Haryana, North India. The cross-sectional study, which was carried out in a tertiary care hospital between September 2021 and April 2023, enrolled participants who met WHO criteria for probable dengue fever. Blood samples underwent molecular and serological diagnostics, such as immunochromatographic testing, VIDAS® Dengue NS1 assays, and TRUPCR® Dengue Detection and serotyping kits, in addition to the collection of clinical and demographic data. Dengue was found to be present in 212 of the 536 probable cases, with serotype DENV-2 being the most common. There have also been reports of mixed DENV-1 and DENV-2 infections. Different serotypes caused different lengths of sickness; DENV-2 showed a sustained high RT-PCR positivity. The severity of the disease was linked to distinct serotypes based on significant differences in aspartate aminotransferase (AST) levels between individuals with dengue fever (DF) and dengue haemorrhagic fever (DHF). The study emphasizes how complicated dengue virus infections can be because of the co-circulation of several serotypes and the possibility of mixed infections. Serotypes and illness severity are correlated, which emphasizes the necessity of continuous surveillance and monitoring to improve outbreak prediction and management. These results are critical for guiding clinical judgments and public health policy, especially with relation to the possible introduction of a dengue vaccine.