Browse publications by year: 2023

  1. Abstracts of the 13th Asia-Pacific International Academy of Pathology Congress 2023 held 16th to 18th June 2023
    Malays J Pathol, 2023 Aug;45(2):299-313.
    PMID: 37658541
    No abstract available.
    MeSH terms: Asia; Humans
  2. Fulltext Detection of novel coronaviruses from dusky fruit bat (Penthetor lucasi) in Sarawak, Malaysian Borneo
    Habeebur-Rahman SP, Noni V, Khan FAA, Tan CS
    Vet Med Sci, 2023 Nov;9(6):2634-2641.
    PMID: 37658663 DOI: 10.1002/vms3.1251
    BACKGROUND: Sarawak has one of the highest diversity of fruit bats species (family Pteropodidae) in Malaysia, with 19 species described. Most coronavirus (CoV) studies have mainly focused on insectivorous bats, resulting in a lack of information on CoVs present in frugivorous bats. In addition, bat CoV surveillance activities are lacking in Malaysia.

    OBJECTIVES: Our study focuses on determining the presence of bat CoVs in dusky fruit bat (Penthetor lucasi).

    METHODS: Guano samples belonging to P. lucasi were collected from Wind Cave Nature Reserve. The samples were screened for the presence of CoVs using validated hemi-nested consensus RNA-dependent RNA polymerase consensus primers.

    RESULTS: The bat CoV positivity rate was 38.5% (n = 15/39), with the viruses belonging to two subgenera: Alphacoronavirus (α-CoV) and Betacoronavirus (β-CoV). Phylogenetic analysis revealed that CoVs from 14 samples of P. lucasi belong to the genus α-CoV and may represent previously described genetic lineages in insectivorous bats in Wind Cave. However, only one sample of P. lucasi was detected with β-CoV which is closely related to subgenus Nobecovirus, which is commonly seen in frugivorous bats.

    CONCLUSIONS: This study provides the first available data on CoVs circulating in P. lucasi.

    MeSH terms: Animals; Borneo; Chiroptera*; Malaysia; Phylogeny
  3. In silico screening of plant peptides against the envelope protein of dengue virus
    Reena G, Ranjani R, Goutham KD, Sangeetha K
    Trop Biomed, 2023 Jun 01;40(2):124-128.
    PMID: 37650397 DOI: 10.47665/tb.40.2.001
    Peptide therapeutics are found to be an emerging and attractive class of treatment due to their highly specific and safe nature. Hence twenty plant peptides were subjected to screening by molecular docking against the envelope protein of the dengue virus using Clus Pro, Patch Dock, and HADDOCK servers. Physicochemical parameters, allergenicity, and toxicity profile of the plant peptides were estimated by Protparam analysis, AllergenFP, and ToxinPred web servers. Six potential compounds namely Ginkbilobin, Cycloviolin-D, Circulin-B, Circulin-A, Cycloviolacin-013, and Circulin-C showed the highest binding energy with both nonallergenic and nontoxic properties. They also exhibited desirable half-lives extending to 30 hrs except for Ginkbilobin, which showed the least half-life of 4.4 hours and non-polar activity. The residues of Ala-4 of Ginkbilobin; Arg-30 of Cycloviolin D; Arg-29 of Circulin A and C interacted with the Try 101 of the domain II of Envelope protein, implying the possible inhibition of the insertion process of the trimeric E protein during fusion with the host cells. Thus, the identified plant peptides could serve as potential leads upon further subjection to in vitro studies.
    MeSH terms: Dengue Virus*; Molecular Docking Simulation
  4. Design of a multi-epitope subunit vaccine candidate for chikungunya virus using computational methodology
    Tongco AMP, Rivera WL
    Trop Biomed, 2023 Jun 01;40(2):129-137.
    PMID: 37650398 DOI: 10.47665/tb.40.2.002
    Chikungunya virus (CHIKV) is a neglected tropical pathogen that causes fever and long-lasting severe arthralgia. Despite its high morbidity, there is still no licensed specific therapeutic option for it. This study proposes a multi-epitope subunit vaccine candidate for CHIKV, designed using computational methods. It was based on the E2 spike glycoprotein in CHIKV, from which T- and B-cell epitopes were predicted and then refined. The pan HLA DR-binding epitope (PADRE) was added to this refined construct, then simulated compared with the native protein, where it was predicted to elicit more than twice the number of antibody titers. Thus, this construct is potentially effective against CHIKV, which further experimentation using live models would be able to verify. This study also demonstrates the feasibility of using rational tools in the future to further optimize vaccine design.
    MeSH terms: Chikungunya virus*; Fever; Humans; Epitopes, B-Lymphocyte; Vaccines, Subunit
  5. Current status of infectious diseases among migrants and non-citizens in Malaysia
    Mohd Putera NWS, Azman AS, Mohd Zain SN, Yahaya H, Lewis JW, Sahimin N
    Trop Biomed, 2023 Jun 01;40(2):138-151.
    PMID: 37650399 DOI: 10.47665/tb.40.2.003
    The mass movement of migrants to Malaysia for employment is one of the factors contributing to the emergence and re-emergence of infectious diseases in this country. Despite mandatory health screening for migrants seeking employment, prevalence records of infectious diseases amongst migrant populations in Malaysia are still within negligible proportions. Therefore, the present review highlights the incidence, mortality and overall status of infectious diseases amongst migrants' populations in Malaysia, which maybe be useful for impeding exacerbation of inequalities among them and improving our national health system thru robust and effective emergency responses in controlling the prevalent diseases found among these populations and maybe, Malaysian citizens too. Peer-reviewed articles from January 2016 to December 2020 were searched through online platform including SCOPUS, PubMed, Science Direct, and Google Scholar. Non-peer-reviewed reports and publications from ministry and government websites including data from related agencies were also scoured from in order to ensure that there are no cases being overlooked, as most published articles did not have migrants as the research subjects. A total of 29 studies had been selected in the final analysis. Migrants in Malaysia were at higher risk for tuberculosis, malaria, lymphatic filariasis, cholera, leprosy and leptospirosis. Lymphatic filariasis was still endemic among this population while thousand cases of TB and cholera had been reported among them due to cramp living conditions and poor sanitation in their settlements respectively. While malaria had gradually decreased and become sporadic, the influx of migrant workers had led to the rising of imported malaria cases. Low cases of leprosy had been recorded in Malaysia but a significant proportion of it was contributed by migrant workers. As for leptospirosis, studies found that there are prominent cases among migrant workers, which particularly highest within workers with lower educational attainment. Infectious diseases are still prevalent among migrants in Malaysia due to various interplay factors including their working sectors, country of origin, immunization status, type of settlement, impoverished living conditions, and language and cultural barriers that impeding access to health facilities.
    MeSH terms: Cholera*; Elephantiasis, Filarial*; Humans; Malaysia/epidemiology; Transients and Migrants*
  6. Antibacterial and antibiotic potentiating capabilities of extracts isolated from Burkillanthus malaccensis, Diospyros hasseltii and Cleisthanthus bracteosus against human pathogenic bacteria
    Kathirvalu G, Chandramathi S, S A A, Atiya N, Begum S, Christophe W, et al.
    Trop Biomed, 2023 Jun 01;40(2):152-159.
    PMID: 37650400 DOI: 10.47665/tb.40.2.004
    Antibiotics which once a boon in medicine and saved millions of lives are now facing an ever-growing menace of antibacterial resistance, which desperately needs new antibacterial drugs which are innovative in chemistry and mode of action. For many years, the world has turned to natural plants with antibacterial properties to combat antibiotic resistance. On that basis, we aimed to identify plants with antibacterial and antibiotic potentiating properties. Seventeen different extracts of 3 plants namely Burkillanthus malaccensis, Diospyros hasseltii and Cleisthanthus bracteosus were tested against multi-drug resistant Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Methicillinresistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA). Antibacterial activity of hexane, methanol and chloroform extracts of bark, seed, fruit, flesh and leaves from these plants were tested using, disk diffusion assay, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Antibiotic potentiating capabilities were tested using time-kill assay. B. malaccensis fruit chloroform extract showed the biggest zone of inhibition against MRSA (13.00±0.0 mm) but C. bracteosus bark methanol extract showed the biggest inhibition zone against MSSA (15.33±0.6 mm). Interestingly, bark methanol extract of C. bracteosus was active against MRSA (8.7±0.6 mm), MSSA (7.7±0.6 mm) (Gram-positive) and A. baumannii (7.7±0.6 mm) (Gram-negative). Overall, the leaf methanol and bark methanol extract of C. bracteosus warrants further investigation such as compound isolation and mechanism of action for validating its therapeutic use as antibiotic potentiator importantly against MRSA and A. baumannii.
    MeSH terms: Methanol/pharmacology; Chloroform/pharmacology; Humans; Rutaceae/chemistry; Diospyros/chemistry; Phyllanthus/chemistry
  7. Prevalence and risk factors for infection with Entamoeba histolytica/dispar/ moshkovskii complex in people living in the slightest and outermost islands of Indonesia
    Junaidi -, Asmaruddin MS, Kurrohman T, Nurdin -, Khazanah W
    Trop Biomed, 2023 Jun 01;40(2):160-164.
    PMID: 37650401 DOI: 10.47665/tb.40.2.005
    Entamoeba histolytica (E. histolytica), the causative agent of amoebiasis, is still a global public health problem that cannot be controlled, especially in tropical and subtropical countries. This study was conducted to obtain information about the incidence of Entamoeba histolytica/dispar/ moshkovskii complex infection and the factors that influence it. The prevalence of infection with the Entamoeba histolytica/dispar/moshkovskii complex and the factors that influence it in people living on the smallest and outermost island of Indonesia, Sabang Island, Aceh Province. This study involved 335 respondents aged >= 10 years. Respondents were selected by non-probability sampling technique. Interviews and observations were conducted to identify risk factors. The Entamoeba histolytica/dispar/ moshkovskii complex was identified by direct examination, concentration, and Whitley's trichrome staining techniques. A Chi-Square test was performed to analyze the correlation of risk factors with the incidence of infection. The prevalence of infection with the Entamoeba histolytica/dispar/ moshkovskii complex in the people of Sabang Island was 26.6% (89/335). Source and adequacy of clean water correlated with the incidence of Entamoeba histolytica/dispar/moshkovskii complex infection. Demographic variables are not correlated with the incidence of infection. However, the group of women aged > 61 years, unemployed, unmarried, and earning less than the regional minimum wage tend to be more likely to be found with Entamoeba histolytica/dispar/moshkovskii complex infections. Thus it can be concluded that the prevalence of infection with the Entamoeba histolytica/dispar/moshkovskii complex on Sabang Island is in the high category. The prevalence of E. histolytica as the causative agent of amoebiasis cannot be explained with certainty because the two identical non-pathogenic Entamoeba species cannot be distinguished by microscopic identification. Sources and adequacy of clean water correlate with the incidence of Entamoeba histolytica/dispar/moshkovskii complex infection in the people of Sabang Island.
    MeSH terms: Amebiasis*; Entamoeba histolytica*; Female; Humans; Indonesia/epidemiology; Risk Factors; Water; Prevalence
  8. Post-mortem pulmonary tuberculosis: comparison of available diagnostic methods
    Chainchel Singh MK, Johari B, Naik VR, Lai PS, Siew SF
    Trop Biomed, 2023 Jun 01;40(2):165-169.
    PMID: 37650402 DOI: 10.47665/tb.40.2.006
    Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a serious public health threat with the World Health Organisation (WHO) reporting 5.8 million cases and 1.3 million deaths in the year 2020 due to TB. TB can be diagnosed by imaging, histopathological and bacteriological methods with culture remaining the gold standard. This study was performed to look at the sensitivity and specificity of post-mortem computed tomography (PMCT) imaging when compared to culture in diagnosing pulmonary tuberculosis. This was a retrospective comparative study looking at post mortem cases where lung tissue samples sent for TB culture at Hospital Kuala Lumpur were compared against PMCT imaging. Exclusion criteria included contaminated samples, decomposed cases, immunocompromised subjects and those below 18 years of age. Subjects included 80 medico-legal autopsy cases at the National Institute of Forensic Medicine, Hospital Kuala Lumpur, Malaysia who had whole body PMCT done in accordance with the Institute's protocol and tissue samples sent for bacteriology culture for tuberculosis. PMCT findings were positively associated with acid-fast organisms in 23.5 out of 33 cases (71.2%). Our study also showed that PMCT had a sensitivity of 71.3% and specificity of 54.3% (95% CI: 39.5-68.4) in diagnosing TB based on the protocol set in this study. This study showed that there was relatively good agreement between radiological PMCT findings and bacterial culture, suggesting that radiological examination is a relatively reliable tool for preliminary screening and possible diagnosis of TB prior to a postmortem examination which would be beneficial in reducing the risk of transmission of TB to health workers during autopsy.
    MeSH terms: Autopsy; Health Personnel; Humans; Retrospective Studies; Tomography, X-Ray Computed
  9. Bullous cellulitis as an extraordinary manifestation of a Vibrio cholerae O1 Ogawa infection
    Ummu SF, Ding CH, Wahab AA, Tzar MN
    Trop Biomed, 2023 Jun 01;40(2):170-173.
    PMID: 37650403 DOI: 10.47665/tb.40.2.007
    Vibrio cholerae is a gram-negative bacterium synonymous with its namesake disease, cholera. Thus, gastrointestinal symptoms are the norm and V. cholerae is very rarely associated with skin and soft tissue infections. We describe a case of a 63-year-old Chinese woman with multiple medical comorbidities on corticosteroid therapy who developed fever and a painful swelling on her left leg after being pricked by a branch while gardening. There was no abdominal pain, vomiting or diarrhea. A diagnosis of bullous cellulitis was made clinically, and blood was sent for bacteriological culture. A beta-hemolytic commashaped gram-negative bacillus was isolated from the blood. It was also oxidase-positive and produced an acid/alkaline (A/K) reaction on triple sugar iron agar. It was identified biochemically as Vibrio cholerae. After additional testing, it was found to be of the O1 serogroup and Ogawa serotype. The infection resolved following a 10-day course of high-dose co-trimoxazole therapy.
    MeSH terms: Cellulitis/diagnosis; Cellulitis/drug therapy; Female; Humans; Middle Aged; Skin; Abdominal Pain; Vibrio cholerae O1*
  10. Antimicrobial activity of essential oils of Curcuma longa and Syzygium aromaticum against multiple drug-resistant pathogenic bacteria
    Zeshan MQ, Ashraf M, Omer MO, Anjum AA, Ali MA, Najeeb M, et al.
    Trop Biomed, 2023 Jun 01;40(2):174-182.
    PMID: 37650404 DOI: 10.47665/tb.40.2.008
    The present study was conducted to investigate the antimicrobial potential of essential oils of Curcuma longa and Syzygium aromaticum against multidrug-resistant pathogenic bacteria. Four identified bacterial isolates including Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii were selected and their antibiotic sensitivity was checked by disc diffusion assay. C. longa and S. aromaticum were subjected to steam distillation to obtain their essential oils. The crude essential oils were fractioned by employing column chromatography. Crude essential oils and their fractions were evaluated for their antibacterial activity by agar well diffusion assay and minimum inhibitory concentrations were calculated. All the selected bacterial isolates showed resistance to three or more than three antibiotic groups and were declared as multidrugresistant (MDRs). Crude essential oils of C. longa and S. aromaticum exhibited antimicrobial activity against all selected isolates but S. aromaticum activity was better than the C. longa with a maximum 19.3±1.50 mm zone of inhibition against A. baumannii at 1.04 µL/mL MIC. GC/MS analysis revealed the abundance of components including eugenol, eugenyl acetate, b- caryophyllene, and a- Humulene in both crude oil and fractions of S. aromaticum. While the main components of C. longa essential oil were Ar-tumerone, a-tumerone, b- Tumerone, I-Phellandrene, a-zingibirene, b- sesquiphellandrene, and p- Cymene. This study highlights that plant-based essential oils could be a promising alternative to antibiotics for which pathogens have developed resistance. C. longa and S. aromaticum carry compounds that have antimicrobial potential against multiple drug-resistant bacteria including MRSA. E. coli, K. pneumoniae and A. baumannii.
    MeSH terms: Anti-Bacterial Agents/pharmacology; Bacteria; Escherichia coli; Plant Oils; Syzygium*; Curcuma; Methicillin-Resistant Staphylococcus aureus*
  11. Transferable mechanisms of quinolone resistance are more frequent among enterotoxigenic Escherichia coli isolates displaying low-level quinolone resistance
    Medina AM, Rivera FP, Riveros M, Ochoa TJ, Pons MJ, Ruiz J
    Trop Biomed, 2023 Jun 01;40(2):183-187.
    PMID: 37650405 DOI: 10.47665/tb.40.2.009
    This study analysed the mechanisms of quinolone resistance among enterotoxigenic Escherichia coli (ETEC) in a periurban area of Lima, Peru. The susceptibility to nalidixic acid and ciprofloxacin, the role of Phe-Arg-b-Naphtylamyde inhibitable-(PAbN) efflux pumps, the presence of mutations in gyrA and parC as well as the presence of aac(6')Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, qnrVC and oqxAB were determined in 31 ETEC from previous case/control studies of children's diarrhoea. Discordances between disk diffusion, with all isolates showing intermediate or fully resistance to nalidixic acid, and minimal inhibitory concentration (MIC), with 7 isolates being below considered resistance breakpoint, were observed. Twenty-one isolates possessed gyrA mutations (19 S83L, 2 S83A). AAC(6') Ib-cr, QnrS, QnrB and QepA were found in 7, 6, 2 and 1 isolates respectively, with 3 isolates presenting 2 transferable mechanisms of quinolone resistance (TMQR) concomitantly. TMQR were more frequent among isolates with MIC to nalidixic acid ranging from 2 to 16 mg/L (p=0.03), while gyrA mutations were more frequent among isolates with nalidixic acid MIC >= 128 mg/L (p=0.0002). In summary, the mechanisms of quinolone resistance present in ETEC isolates in Peru have been described. Differences in the prevalence of underlying mechanisms associated with final MIC levels were observed. The results suggest two different evolutive strategies to survive in the presence of quinolones related to specific bacterial genetic background.
    MeSH terms: Child; Ciprofloxacin; Humans; Nalidixic Acid/pharmacology; Case-Control Studies
  12. Molecular detection of filarial nematode from Culicoides biting midges (Diptera: Ceratopogonidae) in northeastern Thailand
    Pramual P, Khamluea S, Butlun P, Promdungdee A
    Trop Biomed, 2023 Jun 01;40(2):188-193.
    PMID: 37650406 DOI: 10.47665/tb.40.2.010
    Culicoides Latreille biting midges are important blood feeding insects. Many species are pests and vectors of the disease causing agents including viruses, protozoa and filarial nematodes which can be transmitted to humans and other animals. However, knowledge of the role of Culicoides as vectors of filarial nematodes is limited, particular in Thailand, where at least 100 species of the genus Culicoides have been reported. In this study, a molecular approach using the 12S rRNA gene sequence was used to detecting the filarial nematode in four common biting midge species, C. actoni Smith, C. oxystoma Kieffer, C. peregrinus Kieffer and C. mahasarakhamense Pramual, Jomkumsing, Piraonapicha & Jumpato in animal shelters from northeastern Thailand. A total of 1,721 specimens were used for molecular screening. An unidentified Onchocercidae sp. was detected in a specimen of C. mahasarakhamense collected from Maha Sarakham province. This filarial species shows 93% sequence similarity with an unidentified Onchocercidae sp. isolated from Culex mosquitoes. Phylogenetic analyses revealed that Onchocercidae sp. from C. mahasarakhamense formed a clade with strong bootstrap support (100%) with filarial species detected in birds. Thus, it is very likely that the Onchocercidae sp. found in this study employes birds as vertebrate hosts which agrees with feeding behavior of C. mahasarakhamense which is known to feed on chicken. Further study is requiring to examine whether this biting midge species is a competent vector of this Onchocercidae sp.
    MeSH terms: Animals; Ceratopogonidae*; Humans; Nematoda*; Phylogeny; Thailand; Mosquito Vectors
  13. Molecular identification and in vitro assessment of zoonotic-potential of a novel Orthobunyavirus isolated from broiler chicken in Malaysia
    M M, Azmi MA, Sani NI, Gilbert G, Reduan MHF
    Trop Biomed, 2023 Jun 01;40(2):194-198.
    PMID: 37650407 DOI: 10.47665/tb.40.2.011
    We have previously isolated a novel avian Orthobunyavirus, Kedah Fatal Kidney Syndrome (KFKS) virus from a broiler farm in Kedah, Malaysia in 2020 with a severe kidney lesion in chickens. The virus was designated as KFKS2_CS virus. Sequence analysis of partial nucleocapsid (N) and nonstructural (NSs) sequence of this virus showed the highest sequence identity with previous KFKS1 from Malaysia (100%) and 97% with a zoonotic Umbre (UMB) virus, which was reported to cause encephalitis in immunocompromised humans in India. Phylogenetic analysis revealed that this virus was clustered together with previous KFKS1 virus from Malaysia, UMB and Cristoli viruses. This study aimed to assess the zoonotic potential of this KFKS2_CS virus in vitro by determining its ability to inhibit the production of interferon (IFN) in human glioblastoma multiforme (GBM) brain cells using reverse-transcriptase polymerase reaction (RT-PCR). This virus blocked the production of interferon-a in this human brain cells. In conclusion, this KFKS2_CS virus may have a zoonotic potential and become a public health concern in the future.
    MeSH terms: Animals; Chickens; Humans; Interferons; Malaysia; Phylogeny; Orthobunyavirus*
  14. Post-COVID-19 cryptosporidiosis: A serious risk or mere association?
    Enas AE, Hadel MA, Emad AA, Ibrahim BE, Morsy S, Noha MA
    Trop Biomed, 2023 Jun 01;40(2):199-207.
    PMID: 37650408 DOI: 10.47665/tb.40.2.012
    Post-COVID-19 conditions encompass a wide range of health problems, including enteritis, but their association with parasitic infections has not yet been investigated. This study analyzed gastrointestinal symptoms, medical histories, fecal Cryptosporidium oocysts, and the history of COVID-19 infection in patients who attended the Faculty of Medicine, Cairo University, from January to July 2021. Fecal biomarkers, including H. pylori, occult blood, fecal calprotectin (FCAL), and TNF-a, were measured, and Cryptosporidium spp. genotypes were molecularly characterized among post-COVID-19 patients using RFLP. Preliminary results from 210 post-COVID-19 patients revealed that group 1 (Cryptosporidiumpositive) (n = 49) and group 2 (Cryptosporidium-negative) (n = 161) showed no significant difference in the prevalence rate of diabetes mellitus (DM). While group 2 was linked to diarrhea, only infections with Cryptosporidium post-COVID-19 were related to chronic diarrhea, vomiting, and weight loss. A total of 220 healthy subjects served as negative controls. Administering azithromycin, hydroxychloroquine, and ivermectin was significantly related to an increased risk of Cryptosporidium infection in group 1, whereas only azithromycin was more frequently recorded in group 2. Antioxidant supplementation insignificantly affected the incidence of cryptosporidiosis. Cryptosporidiosis with a history of COVID-19 was linked to H. pylori infections, increased inflammatory biomarkers (FCAL and TNF-a), and occult blood when compared with group 2. Cryptosporidium genotype 1 was the most commonly occurring subset in individuals with post-COVID-19. The findings demonstrated that aggravating gastrointestinal manifestations, increased fecal biomarkers and anti-COVID-19 therapeutic interventions are significantly related to the existence of Cryptosporidium oocysts in patients with post-COVID-19, indicating the predominance of.
    MeSH terms: Cryptosporidium*; Diarrhea; Humans; Azithromycin/therapeutic use
  15. An automated malaria cells detection from thin blood smear images using deep learning
    Sukumarran D, Hasikin K, Mohd Khairuddin AS, Ngui R, Wan Sulaiman WY, Vythilingam I, et al.
    Trop Biomed, 2023 Jun 01;40(2):208-219.
    PMID: 37650409 DOI: 10.47665/tb.40.2.013
    Timely and rapid diagnosis is crucial for faster and proper malaria treatment planning. Microscopic examination is the gold standard for malaria diagnosis, where hundreds of millions of blood films are examined annually. However, this method's effectiveness depends on the trained microscopist's skills. With the increasing interest in applying deep learning in malaria diagnosis, this study aims to determine the most suitable deep-learning object detection architecture and their applicability to detect and distinguish red blood cells as either malaria-infected or non-infected cells. The object detectors Yolov4, Faster R-CNN, and SSD 300 are trained with images infected by all five malaria parasites and from four stages of infection with 80/20 train and test data partition. The performance of object detectors is evaluated, and hyperparameters are optimized to select the best-performing model. The best-performing model was also assessed with an independent dataset to verify the models' ability to generalize in different domains. The results show that upon training, the Yolov4 model achieves a precision of 83%, recall of 95%, F1-score of 89%, and mean average precision of 93.87% at a threshold of 0.5. Conclusively, Yolov4 can act as an alternative in detecting the infected cells from whole thin blood smear images. Object detectors can complement a deep learning classification model in detecting infected cells since they eliminate the need to train on single-cell images and have been demonstrated to be more feasible for a different target domain.
    MeSH terms: Erythrocytes; Humans
  16. Molecular characterization and phylogenetic analysis of avian influenza H3N8 virus isolated from imported waterfowl in Malaysia
    Leow BL, Shohaimi SA, Mohd Yusop FF, Sidik MR, Mohd Saeid FH
    Trop Biomed, 2023 Jun 01;40(2):220-235.
    PMID: 37650410 DOI: 10.47665/tb.40.2.014
    Wild aquatic birds are natural reservoirs of influenza A viruses and H3 subtype is one of the most prevalent subtypes in waterfowl. Two H3N8 viruses of low pathogenic avian influenza (LPAI) were isolated via egg inoculation technique from the fecal swab specimens from imported barnacle goose and paradise shelduck in Veterinary Research Institute Ipoh, Malaysia. The full length of eight gene segments of the two viruses were amplified and sequenced with specific primers. The sequences were molecularly characterized, and the sequence identity were assessed with other published sequences. The two viruses are identical and they possess the same amino acid sequences for all the eight gene segments. The viruses were highly similar to the H3 virus from Netherlands and N8 virus from Belgium respectively. Phylogenetic analysis revealed that all the eight gene segments were grouped in the Eurasian lineage, and genetic reassortment may occur between the internal genes of the H3 viruses and other AI subtypes. Though four amino acid substitutions were identified in the hemagglutinin gene, the viruses retained most of the avian-type receptor binding preference. Few amino acid substitutions were observed in all internal genes. Most of the neuraminidase inhibitors and adamantine resistance related mutation were not seen in the viruses. The replicative capacity, cross species transmissibility, and potential zoonotic risk of the viruses are worth further investigation. As H3 virus poses potential threats to both human and animals, and with the increase in the international trade of birds; strict quarantine practice at the entry point and good laboratory diagnostic capabilities is crucial to prevent the introduction of new AI virus into our country.
    MeSH terms: Animals; Birds; Malaysia; Phylogeny; Internationality
  17. Theileria orientalis Buffeli pathotype in cows in a theileriosis-endemic region of India
    Sahoo S, Sahoo N, Biswal S, Mohanty BN, Behera B, Pahari A
    Trop Biomed, 2023 Jun 01;40(2):236-240.
    PMID: 37650411 DOI: 10.47665/tb.40.2.015
    Oriental theileriosis caused by Theileria orientalis is a growing health concern of lactating cows in its endemic areas. Rapid and sensitive diagnostic tests are demand areas for appropriate and effective prophylactic and therapeutic measures. Quantitative polymerase chain reaction (qPCR) is the answer for both detection and quantification of parasites. Present study deals with qPCR for detection of parasitemia level of T. orientalis in apparently healthy and clinically affected cows. Major piroplasm surface protein (MPSP) gene present in T. orientalis was cloned in pUC57 vector and transformed into E. coli Top 10 cells. Single and mixed infections of hemoprotozoa other than T. orientalis, causing anemia were differentiated through blood smear examination and PCR tests. T. orientalis was detected in 108 (63.15%) ill and 48 (26.66%) healthy cows. Piroplasms detected per 1000 red blood cells (RBCs) was 0-1 in the healthy group as compared to 3-22 in those showing clinical signs. Parasitemia in ill cows ranged between 6.9 × 102 and 4.5 × 103 parasites / µl of blood which was significantly higher (p<0.05) than healthy group (2.6 × 102 - 5.7 × 102 parasites / µl of blood). Phylogenetic study of the isolates showed similarity with Buffeli type that unfolded its pathogenic form in apparently healthy and ill cows.
    MeSH terms: Animals; Cattle; Escherichia coli; Female; India/epidemiology; Lactation; Phylogeny; Parasitemia/veterinary
  18. Insecticidal activity and physiopathological effects of Cotula cinerea crude extract against Culex pipiens
    Trop Biomed, 2023 Jun 01;40(2):241-249.
    PMID: 37650412 DOI: 10.47665/tb.40.2.016
    The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.
    MeSH terms: Acetylcholinesterase; Animals; Culex*; Larva; Asteraceae*; Benzoic Acid
  19. A case report of an uncommon presentation of cutaneous leishmaniasis: A nose lesion
    Alamin AA, Gebreyesus MW, Mohamed I
    Trop Biomed, 2023 Jun 01;40(2):250-252.
    PMID: 37650413 DOI: 10.47665/tb.40.2.017
    Leishmaniasis is a widely spread zoonotic disease caused by the bite of infected sandflies, particularly in developing countries. Cutaneous leishmaniasis can have a diverse range of presentations, ranging from minor skin nodules to significant mucosal damage. However, nose involvement is infrequent. Our report highlights a 15-year-old female patient with a persistent skin lesion on her nose for three months, which is a rare manifestation of cutaneous leishmaniasis. The lesion started as a raised spot with a brownish-red color and a crust but eventually developed into an ulcer that spread over the entire lobe of the nose and even moved toward the eye. Microscopic examination revealed the presence of Leishmania amastigotes, and a biopsy confirmed a diagnosis of cutaneous leishmaniasis. The patient received daily intravenous sodium stibogluconate doses of 9 mg/kg for 20 days, and three weeks later, there was a significant clinical improvement, with the ulcer beginning to heal and no more amastigotes visible on microscopic examination. It is crucial to keep cutaneous leishmaniasis in mind as a possible diagnosis for patients with skin lesions, even in regions where the condition is not prevalent.
    MeSH terms: Adolescent; Animals; Antimony Sodium Gluconate/therapeutic use; Female; Humans; Leishmania*; Ulcer; Zoonoses
  20. Antibiosis interaction of black soldier flies (Hermetia illucens) (Diptera: Stratiomyidae) with house fly (Musca domestica) (Diptera: Muscidae)
    Tangkawanit U, Ardburai W
    Trop Biomed, 2023 Jun 01;40(2):253-258.
    PMID: 37650414 DOI: 10.47665/tb.40.2.018
    Black soldier fly (Hermetia illucens (Linnaeus, 1758)) larvae inhibit oviposition of house fly (Musca domestica Linnaeus, 1758) by releasing a semiochemical, although in some situations, inhibition is only partial. We hypothesized that there is a certain period in the life cycle of black soldier fly when it can cause antibiosis of the house fly. Choice and non-choice tests were used to separately examine the effectiveness of each developmental stage of black soldier fly (egg, larval (phase I, II, and III), prepupal and pupal stages) and crude extract of larvae on house fly oviposition. Tests using each developmental stage were compared with controls lacking black soldier fly. The effects of black soldier fly on the number of newly hatched house fly larvae were evaluated and there was a significant difference between the test and control in the number of eggs laid by house fly for all phases of the black soldier fly larval stage. Strong inhibition was found in some black soldier fly larval phases. Significant differences in the numbers of house fly eggs oviposited in food containers treated with crude extract were found when compared with a control, confirming that chemicals from black soldier fly larvae resulted in inhibition of oviposition of house fly. The results from experiment also indicated that chemicals from black soldier larvae influenced the number of house fly larvae newly hatched from eggs.
    MeSH terms: Animals; Antibiosis*; Female; Houseflies*; Larva; Oviposition; Simuliidae*
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