Browse publications by year: 2020

  1. Rangkakulnuwat P, Sanit S, Lao-Araya M
    Trop Biomed, 2020 Jun 01;37(2):318-323.
    PMID: 33612801
    Domestic mites have been recognized as the most common allergen responsible for respiratory allergy. Herein, we report a case of anaphylaxis due to ingestion of dust mitecontaminated food. A 14-year-old boy presented to the Emergency Department with chest discomfort, wheezing, eyelid angioedema, and urticarial rash twice in a month after eating meals, including tempura fried squids and onion fritters (containing wheat flour, eggs, squid, and onion). Anaphylaxis had been diagnosed and successfully treated. The investigations showed that the patient was sensitive to house dust mites. Positive skin prick-to-prick test response to incriminated flour and negative tests to wheat allergen extract and uncontaminated flour were demonstrated. The microscopic analysis of causative cooking flour identified the presence of Dermatophagoides farinae. During the oral food challenge test, the patient was able to eat tempura-fried squids and onion fritters, made with uncontaminated flour, without any adverse reaction. Hence, oral ingestion of dust mite-contaminated food was the culprit of this severe allergic reaction.
    MeSH terms: Adolescent; Anaphylaxis/etiology*; Angioedema; Animals; Food Contamination*; Humans; Male; Skin Tests; Thailand; Urticaria; Triticum; Antigens, Dermatophagoides; Dermatophagoides farinae*
  2. De Silva JR, Ching XT, Lau YL
    Trop Biomed, 2020 Jun 01;37(2):324-332.
    PMID: 33612802
    The focus of the current study was to disrupt the Toxo 5699 gene via CRISPR/Cas9 to evaluate the effects of gene disruption on the parasite lytic cycle. In the present work, a single plasmid expressing both the guide RNA and Cas9 nuclease together with a selectable marker of human dihydrofolate reductase (DHFR) was introduced into Toxoplasma gondii. Targeted disruption of the Toxo 5699 gene was carried out via the CRISPR/Cas9 system and confirmed by PCR, sequencing, and immunofluorescence microscopy. Disrupted and nondisrupted control parasites were allowed to invade HS27 cell monolayers and plaques were counted. The average number of plaques from three replicates per group was obtained between the disrupted and non-disrupted T. gondii RH strain and was compared using a onetailed t-test. It was observed that there was a significant decrease in number and size of plaque formation in the Toxo 5699 gene disrupted parasite line. This is an indication that the Toxo 5699 gene may play a role in the lytic cycle of the parasite, particularly during the replication phase and thus would be a novel target for disruption or silencing. The Toxo 5699 gene presented in the current work is an important part of the T. gondii lytic cycle, therefore meriting further inquiry into its potential as a target for further genetic-silencing or disruption studies.
    MeSH terms: Base Sequence; Cell Line; Humans; Plasmids; Toxoplasma/genetics*; Toxoplasma/pathogenicity*; Genes, Protozoan*; CRISPR-Cas Systems
  3. Nordin NH, Ahmad UK, Abdul Rahim NA, Kamaluddin MR, Ismail D, Muda NW, et al.
    Trop Biomed, 2020 Jun 01;37(2):333-356.
    PMID: 33612803
    In addition to the scarcity of forensic entomology baseline data on oviposition of necrophagous insects and completion of their life cycles in the Borneo region, similar data derived from caves remain unreported. Since entomological baseline data can differ from one biogeoclimatic region to another, the lack of such data would limit the practical values of applying entomological evidence in estimating minimum postmortem interval (mPMI). Therefore, this present research that investigated oviposition and completion of life cycles of necrophagous flies infesting rabbit carcasses decomposing in Mount Kapur Cave and its surrounding forest habitat in Kuching, Sarawak merits forensic consideration. In general, 13 taxa of necrophagous flies were identified viz. Hypopygiopsis violacea, Hypopygiopsis fumipennis, Hemipyrellia ligurriens, Hemipyrellia tagaliana, Chrysomya megacephala, Chrysomya villeneuvi, Chrysomya rufifacies, Chrysomya chani, Chrysomya pinguis, Chrysomya nigripes, Ophyra spinigera and Ophyra chalcogaster, as well as unidentified Sarcophagidae. In addition, Hyp. violacea and Hyp. fumipennis were the two earlier necrophagous flies that oviposited in all rabbit carcasses decomposing in both habitats. While all these necrophagous flies were observed infesting carcasses in Mount Kapur Cave, Hem. ligurriens and Hem. tagaliana were not found infesting carcasses in the surrounding forest habitat. Complete life cycles for six and five different necrophagous fly species were successfully observed in Mount Kapur Cave and its surrounding forest habitat, respectively. Significant delay in oviposition, as well as longer durations for completing the life cycles in several necrophagous fly species were observed in Mount Kapur Cave when compared with those of surrounding forest habitat (p < 0.05). These findings deserve consideration as the first ever forensic empirical baseline data on oviposition and completion of life cycles for necrophagous flies in Sarawak as well as in a cave habitat, in view of its practical values for estimating mPMI for forensic practical caseworks.
    MeSH terms: Animals; Cadaver; Diptera/classification*; Female; Larva; Malaysia; Oviposition; Rabbits; Caves*
  4. Ilham NE, Joseph NSM, Bahtiar Affendy N, Mohd Taib N, Vasantha KN, Masri SN
    Trop Biomed, 2020 Jun 01;37(2):357-362.
    PMID: 33612804
    Leptospirosis is a common febrile illness in Malaysia. The disease is caused by pathogenic bacteria called leptospires that are transmitted directly or indirectly from animals to humans via contaminated water or soil. It is a potentially serious but treatable disease. Its symptoms may mimic those of other unrelated febrile illnesses such as dengue, influenza, meningitis, hepatitis or viral haemorrhagic fevers. The spectrum of the disease is extremely wide, ranging from subclinical infection to a severe syndrome of multiorgan infection with high mortality. The diagnosis requires high suspicion with history of exposure to water or environment possibly contaminated with infected animal urine. This is a case of a 13 year-oldgirl with no known medical illness, and a history of exposure to outdoor activities. However, paired sera for leptospirosis serology was not diagnostic. She then developed septic shock on day 14 of illness. But due to high suspicion of leptospirosis, antibiotic therapy was upgraded to ceftriaxone and samples were sent for further testing which revealed that leptospires were detected in the urine, using molecular technique. She improved after treated as leptospirosis.
    MeSH terms: Adolescent; Female; Humans; Leptospirosis/diagnosis*; Malaysia; Serologic Tests; Shock, Septic/microbiology; Molecular Diagnostic Techniques
  5. Sahimin N, Abd Khalil NS, Lewis JW, Mohd Zain SN
    Trop Biomed, 2020 Jun 01;37(2):363-371.
    PMID: 33612805
    The health impact of a Malaysian national helminth control program which provided school-based anthelmintic chemotherapy from 1974 to 1983 was re-visited after three decades post MDA and associated risk factors amongst urban poor communities identified. Stool samples collected were screened using the formalin ethyl-acetate concentration technique recovered at least one species of helminth and/or protozoan. Despite a steady decline observed between 1974-1983 however, post MDA infections continue to persist in pockets of communities moderately (18.9%; n=39/206) with higher infection recorded amongst PPR flat residents (22.5%, n=16/71). Among risk factors identified, waste management method was the primary factor for Ascaris lumbricoides infections (n=33; 16.0%), whereas age, education, employment and source of drinking water were significant risk factors for cryptosporidiosis. Despite the government's efforts to improve health through the provision of basic amenities to the general public, higher prevalence values amongst PPR flat dwellers suggests the need to implement targeted chemotherapeutic treatment of, once a year deworming as recommended by World Health Organization when the baseline prevalence of soil-transmitted helminth infections in the community is over 20%, in addition to preventive measures though improvements in health awareness programs and improved waste management methods.
    MeSH terms: Adolescent; Adult; Anthelmintics/administration & dosage*; Anthelmintics/therapeutic use; Child; Female; Humans; Intestinal Diseases, Parasitic/drug therapy*; Intestinal Diseases, Parasitic/epidemiology; Health Knowledge, Attitudes, Practice; Life Style; Malaysia/epidemiology; Male; Middle Aged; Poverty Areas; Risk Factors; Soil/parasitology; Urban Population; Prevalence; Vulnerable Populations; Young Adult
  6. Nguyen MH, Dao QM, Bui TTH, Le VHT
    Trop Biomed, 2020 Jun 01;37(2):372-378.
    PMID: 33612806
    Interleukin (IL)-1 beta (IL-1β), IL-2, Interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) in the pleural fluid are valuable biomarkers in early diagnosis of Tuberculous Pleural Effusion (TPE). This study aimed to analyze the diagnostic values of some cytokines (IFN-γ, TNF-α, IL-1β, and IL-2) in pleural fluid for identifying TPE in Vietnam. We performed a cross-sectional study on tuberculosis (TB) patients with pleural effusion. Pleural IFN-γ, TNF-α, IL-1β, IL-2 were measured by ELISA® Kit (Abcam, USA) on Biotek system. Receiver operating characteristic curves (ROC), an area under the curve (AUC), sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy (ACC) of IFN-γ, TNF-α, IL-1β, IL-2 in identifying TBE were assessed. Among 386 patients, 234 (60,6%) had TPE, and 152 (39,4%) did not have TPE. The median of IL-2, TNF-α, and IFN-γ levels were significantly higher in TPE compared to the non-TPE group (p<0.05). AUC for IL-1β, IL-2, TNF-α, and IFN-γ were 0.54, 0.57, 0.62. 0.84 (p<0.05), respectively. The sensitivity of IL-1β, IL-2, TNF-α, and IFN-γ in the diagnosis of TPE were 82.1, 53.4, 77.8, and 80.3, while the specificity was 28,4, 69.7, 47.4, and 80.9, respectively. IFN-γ and TNF-α are potential biomarkers in diagnosing TPE.
    MeSH terms: Adult; Aged; Cross-Sectional Studies; Female; Humans; Interferon-gamma; Interleukin-2; Male; Middle Aged; Pleural Effusion/diagnosis*; Predictive Value of Tests; Sensitivity and Specificity; Tuberculosis, Pleural/diagnosis*; Tumor Necrosis Factor-alpha; Vietnam; Biomarkers/analysis; Cytokines/analysis*; Area Under Curve; Interleukin-1beta
  7. Nisha M, Aiman M, Asyhira N, Syafiq H, Atiqah N, Kumarasamy V, et al.
    Trop Biomed, 2020 Jun 01;37(2):379-388.
    PMID: 33612807
    Soil-transmitted helminth (STH) could possibly cause mild to severe health effects such as diarrhea, weakness, intestinal blood loss, and impaired cognitive development and growth. In Malaysia, previous studies depicted a high prevalence rate of STH was due to poor hygiene practice and low efficacies of anthelminthic drugs. This study was conducted to investigate hand hygiene practice and WASH criteria's (Water, sanitation and hygiene) related to STH infection among two indigenous tribes in Peninsular Malaysia. A cross-sectional study was carried out to study the relationship among STH infection compared to water quality, sanitation, and hygiene conditions. A total of 190 individuals from two indigenous villages participated in the study, with ages ranging from 5 to 60 years old. In addition, Pearson's Chisquare (X2) test was utilized to test the relationship among STH with demographic socioeconomic and behavioral factors. The confidence interval (CI) of 95% is used to estimate the precision of the odds ratio (OR). Multivariate logistic regression models were also used to identify the risk factors associated with STH infections. The overall findings indicated a prevalence rate of 72% for STH, and distributed mainly among children aged < 12 years. Furthermore, multivariate analyses using logistic regression revealed chronic health problems, incorrect hand washing, and walking bare footed were associated with STH infection. Overall results indicated high prevalence of STH among the indigenous villagers, which aligns with the published literature and proves to be a problem need to be addressed as neglected disease. Interestingly, there was a significant relationship between the presences of chronic diseases and STH infection, which prompted other questions the awareness needs to be educated and the simple and low-cost intervention on the proper way of hand washing may help to reduce STH infection in these indigenous communities.
    MeSH terms: Adolescent; Adult; Aged; Child; Child, Preschool; Cross-Sectional Studies; Female; Hand Disinfection; Helminthiasis/ethnology; Helminthiasis/epidemiology*; Humans; Hygiene; Malaysia; Male; Middle Aged; Risk Factors; Rural Population; Sanitation; Soil/parasitology*; Prevalence; Young Adult
  8. Najib MA, Noor-Izani NJ, Wan-Nor-Amilah WAW, Wong WK, Faez AM
    Trop Biomed, 2020 Jun 01;37(2):389-396.
    PMID: 33612808
    Human fascioliasis is a public health problem particularly in areas where ruminants are raised. The aims of this study were to determine the seroprevalence of anti-Fasciola antibody and the associated risk factors among cattle farm workers and dwellers in Kelantan. A total of 90 blood samples were collected in this cross-sectional study. A set of validated questionnaire was used to obtain information on socio-demographic profiles and dietary habits of participants. The sera were subjected to enzyme linked immunosorbent assay (ELISA) for the detection of anti-Fasciola IgG antibody. The association between seropositivity and the significant risk factors were determined via logistic regression. From the result, serological screening revealed 60 (67%) participants positive for anti-Fasciola IgG antibody. The factors found to be significantly associated with seropositivity against anti-Fasciola IgG antibody were the age group of 18 years old and above with calculated odds ratio of 3.2 times (p=0.032) and the duration of farming activities of more than 5 years with calculated odds ratio of 2.6 times (p=0.036). In conclusion, Fasciola infection is prevalent among cattle farm workers and dwellers in Kelantan.
    MeSH terms: Farmers*; Adolescent; Adult; Aged; Animals; Antibodies, Helminth/blood; Cattle; Child; Cross-Sectional Studies; Enzyme-Linked Immunosorbent Assay; Fascioliasis/diagnosis*; Fascioliasis/epidemiology; Female; Humans; Immunoglobulin G/blood; Malaysia/epidemiology; Male; Middle Aged; Seroepidemiologic Studies; Young Adult
  9. Kittiwattanawong K, Ponlawat A, Boonrotpong S, Nanakorn N, Kongchouy N, Moonmake S, et al.
    Trop Biomed, 2020 Jun 01;37(2):397-408.
    PMID: 33612809
    The Anopheles dirus mosquito is a primary malaria vector that transmits many species of Plasmodium parasites in Thailand and is widely spread across its geographic area. In the current study, the levels of expression of the suppressor of cytokine signaling (SOCS) gene in An. dirus mosquitoes infected with P. vivax were examined. The level of the gene's expression determined by mRNA extraction in An. dirus females (n=2,400) was studied at different times (0, 12, 24, 36, and 48 h after feeding), with different types of blood feeding (non-feeding, parasite-negative blood feeding, parasite-positive blood feeding) and in different parts of the body of mosquito samples (thorax and abdomen). The datasets were analyzed based on their relative expression ratio by the 2-ΔΔCT method and were tested for significant differences with ANOVA. The results showed that the An. dirus SOCS gene was stimulated in the abdomen 12 h and 24 h after blood feeding about three times more highly than in unfed females, with the difference being significant. At 24 h after P. vivax-infected blood feeding, the SOCS gene in the abdomen was expressed more highly than 24 h after parasite-negative blood feeding and expression was almost 36 times higher than in the control group who were not fed blood. However, in the thorax at all times after feeding and non-feeding, there was no expression of the SOCS gene. Therefore, the SOCS gene in An. dirus was most highly expressed 24 h post-feeding with a P. vivax-infected bloodmeal, which indicates that the SOCS gene in the major malaria vector in Thailand plays an important role in its immune system and its response to P. vivax infection.
    MeSH terms: Animals; Anopheles/genetics*; Anopheles/parasitology*; Feeding Behavior; Female; Insect Vectors/parasitology; Plasmodium vivax*; Thailand; Insect Proteins/genetics*; Suppressor of Cytokine Signaling Proteins/genetics*; Mosquito Vectors/parasitology
  10. Daha SK, Koirala B, Chapagain D, Lohani P, Acharya S, Sharma P
    Trop Biomed, 2020 Jun 01;37(2):409-420.
    PMID: 33612810
    Novel coronavirus disease, the latest world pandemic is one of the most contagious viral infections to date. There has been a lack of uniformity on recognizing this condition clinically because of poorly understood pathophysiology and clinical nature. Also due to ongoing clinical trials, its management is also varied. This is a systematic review from evidence-based studies until March 1st, 2020, covering an update on its clinical features and management. This study shows the multisystem involvement of COVID-19 with dominant respiratory features followed by the musculoskeletal, gastrointestinal system and others. The clinical features varied from asymptomatic to severe forms. Major causes of fatality were acute respiratory distress syndrome, shock, acute cardiac injury, acute kidney injury, rhabdomyolysis, and arrhythmia. Major modalities of management included supportive, antiviral and antibiotic therapy. There was no direct relationship between the specific treatment and the outcome.
    MeSH terms: Humans; Musculoskeletal System/physiopathology; Musculoskeletal System/virology; Respiratory System/physiopathology; Respiratory System/virology; Gastrointestinal Tract/physiopathology; Gastrointestinal Tract/virology; Pandemics*
  11. Hangsawek A, Chutasripanich S, Kammaled P, Rawangchue T, Jirapattharasate C, Moonarmart W, et al.
    Trop Biomed, 2020 Jun 01;37(2):421-432.
    PMID: 33612811
    The occurrence of canine hepatozoonosis in Thailand is primarily caused by Hepatozoon canis. Recently, the relationship of hematology and biochemistry with this disease has been studied, but knowledge regarding the relationship between the quantity of H. canis intracellular gamonts and the hematological profile has not yet been reported. The objective of this study was to investigate the clinical, hematological and biochemical profile of H. canis-positive dogs and the relationship of the number of H. canis gamonts, animal signalment, and hematological and biochemical values. A total of 185 H. canis-positive blood samples were examined, including buffy coat smears and comprehensive data. The number of gamonts was randomly counted from buffy coat smears samples (75/185). The dogs infected with H. canis presented to the animal hospital mostly for health status checks, anorexia, or accidents. Observations from the physical examination on the first day of registration included systemic abnormalities such as digestive, integument, respiratory, urogenital, etc. Most of the dogs showed clinical signs of systemic abnormality in more than one system. Our study shows that plasma proteins are correlated with the number of H. canis gamonts, using Spearman's rho correlation coefficient with significant difference (p <0.05). This finding could be applied to improve the diagnosis and treatment of canine hepatozoonosis.
    MeSH terms: Animals; Coccidiosis/epidemiology; Coccidiosis/veterinary*; Dog Diseases/epidemiology*; Dog Diseases/parasitology; Dogs; Female; Male; Thailand/epidemiology; Prevalence; Eucoccidiida*
  12. Shezryna S, Anisah N, Saleh I, Syamsa RA
    Trop Biomed, 2020 Jun 01;37(2):433-442.
    PMID: 33612812
    Rhipicephalus (Boophilus) microplus serves as an important ectoparasite of livestock and a vector of several pathogens resulting in diseases, subsequently affecting the agricultural field as well as the economy. The extensive use of synthetic acaricides is known to cause resistance over time and therefore a much safer, effective and environmentally friendly alternative to overcome tick infestation should be implemented. Larval immersion tests (LIT) were done to evaluate the effects of Citrus hystrix (Family: Rutaceae) and Cymbopogon citratus (Family: Poaceae) essential oils (EOs) for their individual and combined (1:1) acaricidal activity against the cattle tick. Results showed that LC50 and LC90 values in 24 and 48 hours for Cit. hystrix EO were 11.98% and 24.84%, and 10.95% and 21.71% respectively. LC50 and LC90 values for Cym. citratus EO were 1.21% and 6.28%, and 1.05% and 6.12% respectively. The mixture of EOs from two plants in 1:1 ratio (Cit. hystrix 50%: Cym. citratus 50%) was found to exhibit antagonistic effect (synergistic factor < 1). The 24 hours and 48 hours LC50 and LC90 values for combined EOs were 1.52% and 2.84%, and 1.50% and 2.76% respectively. Individual and combined essential oils were subjected to qualitative analysis using gas chromatography-mass spectrometry (GC-MS) to screen the chemical components present in EOs. Our results showed that the combination of Cit. hystrix and Cym. citratus at 1:1 ratio resulted in an antagonistic effect and the use of Cym. citratus alone is more toxic to R. (B.) microplus, making it a better alternative to chemical based acaricide.
    MeSH terms: Animals; Citrus/chemistry*; Larva; Malaysia; Oils, Volatile/pharmacology*; Plant Oils/pharmacology; Cymbopogon/chemistry*; Rhipicephalus/drug effects*; Acaricides/pharmacology*
  13. Khoa DV, Hoa DT, Anh DN, Van NT, Dung DT, Huong LTT, et al.
    Trop Biomed, 2020 Jun 01;37(2):443-451.
    PMID: 33612813
    Raw or undercooked fish dishes are the major sources of human infection of fishborne trematodes (FBT) and the situation of metacercarial infection in fish greatly affect the prevalence in humans, especially those fish that are commonly used for raw consumption. To investigate the situation of infection with metacercaria of FBT in fish often used to prepare raw fish dishes by local people to assess the risk of infection to humans in Ninh Binh province, Vietnam. 345 fish belonging to five species of freshwater and one species of brackish water fish were collected from fishermen or small-scale fish dealers in Kim Son and Yen Khanh districts, Ninh Binh province between May 2017 and May 2018. Metacercaria of FBT was discovered by pepsin and hydrochloric acid digestion techniques and identified by the morphological and molecular analysis. Among examined fish, 44.06% infected with FBT metacercaria and the highest prevalence was in Cyprinus carpio (86.54%), Ctenopharyngodon idellus (78.43%) and Hypophthalmichthys molitrix (66.67%) while Konosirus punctatus - the brackish water fish - were free from infection. Three species of FBT were found; namely Haplorchis pumilio (accounting for 99.84% of collected metacercariae), Haplorchis taichui and Clonorchis sinensis. The average density was 1.06 metacercariae per gram of freshwater fish and the highest number was of C. idellus (6.38 cysts/gram) followed by Cirrhinus molitorella and C. carpio. Results of the study show the high prevalence of infection of FBT metacercariae among freshwater fish often used to prepare raw fish dishes in Ninh Binh province. These findings suggest the need for greater awareness of the risk from raw fish dishes among public health authorities and people.
    MeSH terms: Animals; Clonorchis sinensis/isolation & purification; Cross-Sectional Studies; Fish Diseases/parasitology*; Fishes/parasitology*; Food Contamination; Heterophyidae/isolation & purification; Trematoda/isolation & purification*; Vietnam; Metacercariae
  14. Shen ZZ, Li K, Li ZJ, Shang XL, Hu F, Zhou WJ, et al.
    Trop Biomed, 2020 Jun 01;37(2):452-457.
    PMID: 33612814
    Toxoplasma gondii is a world-widely spread zoonotic parasite. However, scarce knowledge is known about the prevalence of T. gondii infection in people in Hubei province, China. This study herein was to perform epidemiological investigation of T. gondii infection in people in this region. A total 12527 blood samples were obtained during 2015-2018, and were assayed for T. gondii antibodies of IgG and IgM, respectively by employing an indirect hemagglutination test (IHA). The results discovered that the prevalence of T. gondii in people was 2.44% and 6.1%, respectively based on antibodies of IgG and IgM, respectively. The prevalence was ranged from 0.3% to 5.4% during 2015-2018 based on IgM antibodies. For genders, the prevalence was 0.7% and 2.6% in males and females, respectively based on IgM antibodies. In different years, the prevalence was ranged from 4.9% to 14.0% based on IgG antibodies. The prevalence of T. gondii was 4.9% and 6.6% in males and femalesy based on IgG antibodies. The current results may be helpful for the implementation of preventive measures against Toxoplasma infection among people living in this region.
    MeSH terms: Antibodies, Protozoan/blood; China/epidemiology; Female; Hemagglutination Tests; Humans; Immunoglobulin G/blood; Immunoglobulin M/blood; Male; Toxoplasma; Toxoplasmosis/epidemiology*; Prevalence; Seroepidemiologic Studies
  15. Yang F, Guo KX, Yang DQ, Liu RD, Long SR, Zhang X, et al.
    Trop Biomed, 2020 Jun 01;37(2):458-470.
    PMID: 33612815
    A T. spiralis serine protease 1.2 (TsSP1.2) was identified in the muscle larvae (ML) and intestinal larvae surface/excretory-secretory (ES) proteins by immunoproteomics. The aim of this study was to determine the TsSP1.2 function in the process of T. spiralis intrusion, growth and reproduction by using RNA interference (RNAi). RNAi was used to silence the expression of TsSP1.2 mRNA and protein in the nematode. On 2 days after the ML were electroporated with 2 µM of TsSP1.2-specific siRNA 534, TsSP1.2 mRNA and protein expression declined in 56.44 and 84.48%, respectively, compared with untreated ML. Although TsSP1.2 silencing did not impair worm viability, larval intrusion of intestinal epithelium cells (IEC) was suppressed by 57.18% (P < 0.01) and the suppression was siRNA-dose dependent (r = 0.976). Infection of mice with siRNA 534 transfected ML produced a 57.16% reduction of enteral adult burden and 71.46% reduction of muscle larva burden (P < 0.05). Moreover, silencing of TsSP1.2 gene in ML resulted in worm development impediment and reduction of female fertility. The results showed that silencing of TsSP1.2 by RNAi inhibited larval intrusion and development, and reduced female fecundity. TsSP1.2 plays a crucial role for worm invasion and development in T. spiralis life cycle, and is a potential vaccine/drug target against Trichinella infection.
    MeSH terms: Animals; Female; Intestinal Mucosa/parasitology; Larva; Male; Mice, Inbred BALB C; Muscles/parasitology; Helminth Proteins/genetics; Helminth Proteins/metabolism*; Trichinella spiralis/enzymology*; Trichinella spiralis/genetics; RNA Interference; RNA, Small Interfering; Mice; Serine Proteases/genetics; Serine Proteases/metabolism*
  16. Rasidin RSM, Suhaili Z, Mohamed AFS, Hod R, Neela V, Amin-Nordin S
    Trop Biomed, 2020 Jun 01;37(2):471-481.
    PMID: 33612816
    Nosocomial infection caused by Acinetobacter baumannii is common among immunocompromised patients. Treatment strategy is limited due to rapid resistance development and lack of novel antibiotic. Colistin has been the last line therapy with good in vitro activity against infections caused by multi-drug resistance A. baumannii. However, pharmacological updates are required to support dosing optimisation. This study aimed to determine the time-kill kinetic and resistance development after antibiotic exposure as well as post-antibiotic effect of colistin at different static concentrations in in vitro A. baumannii system. The static in vitro time-kill and post-antibiotic effect experiments were conducted against two clinical isolates as well as one reference isolate ATCC 19606. Time-kill and postantibiotic effect were studied at colistin concentrations ranging from 0.25MIC to 16.0MIC and 0.5MIC to 4.0MIC, respectively. Post-exposure resistance development was examined in time-kill study. Killing activity and post-antibiotic effect were in a concentration-dependent manner. However, delayed killing activity indicates colistin tolerance. Development of resistance after exposure was not detected except for the ATCC 19606 strain. Dosing suggestion based on the observations include administration of supplemental dose 3 MIU at 12 hours after loading dose, administration of maintenance dose 9 MIU in two divided doses and application of extended interval in renal adjustment dose. However, the information is applicable for non-colistin-heteroresistance A. baumannii with colistin MIC < 1.0 mg/L. As for heteroresistance and strain with colistin MIC > 1.0 mg/L, combination therapy would be the more appropriate treatment strategy.
    MeSH terms: Anti-Bacterial Agents/pharmacology*; Colistin/pharmacology*; Microbial Sensitivity Tests*; Drug Resistance, Bacterial; Acinetobacter baumannii/drug effects*
  17. Saleem S, Iqbal A, Hasnain S
    Trop Biomed, 2020 Jun 01;37(2):482-488.
    PMID: 33612817
    Bacterial mediated Silver nanoparticles is considered as an emerging Ecofriendly approach to eradicate human pathogens. This paper aims to provide the biological approach for the synthesis of silver nanoparticles from indigenously isolated bacteria. This study will be beneficial to control the nosocomial infections triggered by MRSA (Methicillin-resistant Staphylococcus aureus). The current study is the extracellular synthesis of silver nanoparticles by using the cell free filtrate of bacterial strains isolated from the soil. The optimization study was also carried out to obtain the maximum production of silver nanoparticles. Nanoparticles were confirmed and characterized by UV-Vis spectroscopy and Transmission Electron Microscopy (TEM) having the plasmon resonance peak between 420-450nm with 10-60nm in size range and most were spherical in shape. Synthesized silver nanoparticles showed a potential antibacterial activity against MRSA (Methicillin Resistant Staphylococcus aureus) in-vitro study. This is the green approach for the production of AgNPs, as there was no previous work done on the synthesis of silver nanoparticles by bacteria in this region of Southern Punjab, Pakistan and these nanoparticles can be used to treat nosocomial infection. These silver nanoparticles can be used in effective disease management as antimicrobial agent.
    MeSH terms: Anti-Bacterial Agents/pharmacology*; Particle Size; Silver/pharmacology*; Soil Microbiology; Microscopy, Electron, Transmission; Metal Nanoparticles/chemistry; Methicillin-Resistant Staphylococcus aureus/drug effects*
  18. Xia NB, Lu Y, Zhao PF, Wang CF, Li YY, Tan L, et al.
    Trop Biomed, 2020 Jun 01;37(2):489-498.
    PMID: 33612818
    Toxoplasma gondii, a ubiquitous pathogen that infects nearly all warm-blooded animals and humans, can cause severe complications to the infected people and animals as well as serious economic losses and social problems. Here, one local strain (TgPIG-WH1) was isolated from an aborted pig fetus, and the genotype of this strain was identified as ToxoDB #3 by the PCR RFLP typing method using 10 molecular markers (SAG1, SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, C22-8, C29-2 and Apico). A comparison of the virulence of this isolate with other strains in both mice and piglets showed that TgPIG-WH1 was less virulent than type 1 strain RH and type 2 strain ME49 in mice, and caused similar symptoms to those of ME49 such as fever in piglets. Additionally, in piglet infection with both strains, the TgPIG-WH1 caused a higher IgG response and more severe pathological damages than ME49. Furthermore, TgPIG-WH1 caused one death in the 5 infected piglets, whereas ME49 did not, suggesting the higher virulence of TgPIG-WH1 than ME49 during piglet infection. Experimental infections indicate that the virulence of TgPIG-WH1 relative to ME49 is weaker in mice, but higher in pigs. This is probably the first report regarding a ToxoDB #3 strain from pigs in Hubei, China. These data will facilitate the understanding of genetic diversity of Toxoplasma strains in China as well as the prevention and control of porcine toxoplasmosis in the local region.
    MeSH terms: Animals; Antibodies, Protozoan/blood; China; Genotype; Immunoglobulin G/blood; Immunoglobulin M/blood; Polymorphism, Restriction Fragment Length; Swine; Swine Diseases/parasitology*; Toxoplasma/genetics*; Toxoplasmosis, Animal/parasitology*; Virulence; Sus scrofa/parasitology*; Mice
  19. Alahmed AM, Nasser MG, Sallam MF, Dawah H, Kheir S, AlAshaal SA
    Trop Biomed, 2020 Jun 01;37(2):499-512.
    PMID: 33612819
    Despite the medical, veterinary and forensic relevance of myiasis-causing flies, knowledge of their diversity in Saudi Arabia is limited especially in the southern region. Therefore, a survey of myiasis-causing flies in the Jazan region was carried out using Red Top Fly Catcher traps baited with either decomposing beef liver or a lure composed primarily from fishmeal during the period April 2013-March 2014. Twelve known species were identified and recorded in this study, seven species of them belonging to Calliphoridae (Chrysomya, Lucilia, and Hemipyrella) and five species belonging to Sarcophagidae (Sarcophaga). Two of these species were recorded for the first time for Saudi Arabia, namely Hemipyrella pulchra (Wiedemann, 1830) and Sarcophaga (Liosarcophaga) exuberans Pandellé, 1896. Images of the species recorded are also provided for the first time. The results expand the knowledge of geographical distribution, fauna, and habitat of the myiasis-causing flies in Saudi Arabia. Biological information and world-wide geographical distribution of these species are included together with some taxonomic remarks.
    MeSH terms: Animals; Goats/parasitology*; Myiasis/veterinary*; Saudi Arabia; Sheep/parasitology*; Sarcophagidae/classification*
  20. Eamsobhana P, Yong HS, Roongruangchai K, Tungtrongchitr A, Wanachiwanawin D
    Trop Biomed, 2020 Jun 01;37(2):536-541.
    PMID: 33612820
    Two female and one male adult hookworms were recovered from a female patient in Thailand. Based on gross and microscopic morphology, the three hookworms are members of Necator americanus. Phylogenetic reconstruction based on partial NADH dehydrogenase subunit 1 (nad1) mitochondrial gene sequences shows that these hookworms belong to the same genetic lineage as N. americanus adult worm from Zhejiang, China. The male and female hookworms were genetically distinct, belonging to two different nad1-haplotypes. This is the first report targeting the nad1 gene on the identification and genetic characterization of the human hookworms originated from infected patient. The nad1 gene marker is useful for species and higher taxa differentiation of hookworms.
    MeSH terms: Aged; Animals; Base Sequence; DNA, Mitochondrial/genetics; Female; Haplotypes; Humans; Male; NADH Dehydrogenase/genetics*; Thailand; Genetic Variation*; Necator americanus/enzymology*; Necator americanus/genetics; Genes, Mitochondrial*
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