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  1. Fulltext Importance of kelch 13 C580Y mutation in the studies of artemisinin resistance in Plasmodium falciparum in Greater Mekong Subregion
    Zaw MT, Lin Z, Emran NA
    J Microbiol Immunol Infect, 2020 Oct;53(5):676-681.
    PMID: 31563454 DOI: 10.1016/j.jmii.2019.07.006
    The mortality caused by Plasmodium falciparum was reduced by Artemisinin (ART) and ART combination therapy (ACT). However, Artemisinin resistance (ART-R) emerge during 2008 in Cambodia and spread to Greater Mekong Subregion (GMS). ART-R was confirmed not to spread to India, a gateway to whole Africa. The whole genome sequencing approach of P. falciparum assumed the k13 gene encoded Kelch protein was discovered to be associated with ART-R. Of the single nucleotide polymorphisms (SNPs) of k13 gene, C580Y mutant was commonly dominant in Cambodia, Myanmar, Thailand, Laos and Vietnam and assumed to be one of strong molecular markers for ART-R in P. falciparum isolates in GMS. Literatures published between 2017 and 2018 were reviewed in this work. F446I is observed to be doubtful molecular marker as ART-R marker. Transgenic experiment showed that parasite with F446I mutation displayed prolonged clearance in respond to ART while C580Y was applied as positive control mutant. Furthermore, study of C580Y allele in four countries Cambodia, Thailand, Laos resulted in single origin whereas the parasite with this allele showed multi-origin in three Provinces of Vietnam. As artemisinin was short acting drug, the role of long acting partner drug was studied by using transgenic C580Y mutant and C580 to leave recrudescent P. falciparum. Recently, there was treatment failure with ACT in some countries in GMS. In this review, the importance of C580Y mutation in the study of ART-R was discussed.
    Matched MeSH terms: Malaria, Falciparum/parasitology
  2. Shift in parasitic infections during the Corona pandemic: a hospital-based retrospective study
    Hawash Y, Ismail KH, Abdel-Wahab M
    Trop Biomed, 2021 Jun 01;38(2):94-101.
    PMID: 34172696 DOI: 10.47665/tb.38.2.038
    The Corona pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) calls on the Saudi government to take action to control the infection. The government closed borders, prohibited travel, limited outdoor movements, and told primary and secondary care facilities to reduce all regular non-urgent health services. It is not known whether these measures have impacted the prevalence of parasitic intestinal infections. This study has therefore been carried out to investigate this issue. Dataset of 217 stool samples submitted to the King Faisal Medical Complex (KFMC) Microbiology Laboratory in Taif, Saudi Arabia for parasitological examination during the pandemic (January-June 2020) and 649 samples submitted during the corresponding months of the previous year (January-June 2019) were extracted and analyzed. Overall, 24.1% (209/866) of samples were parasitespositives; 26.6% (173/649) before and 16.5% (36/217) during the pandemic, with 79% reduction. There was a significant difference in gender-parasitism between the two periods where the majority of parasitism were for males (p<0.001). Infections were frequent in patients aged 5- 14 years both before (84/649; 12.9%) and during (12/217; 5.5%) the pandemic, with significant difference observed between the two cohorts (p<0.002). Moreover, the majority of infected patients were non-Saudi (67.9%; 142/209), with a significant difference in nationality reported, (p=0.024). Protozoa were identified in 21.8% (189) of all samples investigated, of which, Blastocystis hominis, Entamoeba coli, Giardia lamblia, Entamoeba histolytica/dispar and Cryptosporidium species were identified in 6.1% (53), 5.4% (47), 5.0% (44), 2.8% (25), and 2.3% (20), respectively. Helminths were diagnosed in 2.3% (20/866) of samples. Eggs of hookworm, Ascaris, Taenia spp, and Hymenolepis nana were detected in 0.9% (8), 0.5% (5), 0.3% (3) and 0.4% (4), respectively. In parallel with our research hypothesis, a substantial decrease in the burden of intestinal parasitic infections was recorded with the lock-down measures taken during the Corona pandemic.
    Matched MeSH terms: Feces/parasitology
  3. Fulltext Curcuma longa ethanol extract and Curcumin inhibit the growth of Acanthamoeba triangularis trophozoites and cysts isolated from water reservoirs at Walailak University, Thailand
    Mitsuwan W, Bunsuwansakul C, Leonard TE, Laohaprapanon S, Hounkong K, Bunluepuech K, et al.
    Pathog Glob Health, 2020 05 18;114(4):194-204.
    PMID: 32315247 DOI: 10.1080/20477724.2020.1755551
    CURCUMA LONGA: (C. longa) rhizome extract has been traditionally used to treat many infections. Curcumin, a pure compound isolated from the plant, has been documented to possess a wide spectrum of pharmacological effects. The present study aimed to investigate the effects of Thai medicinal plant extracts including C. longa extract and Curcumin on Acanthamoeba triangularis, a causative agent of human Acanthamoeba keratitis. The parasite was isolated from the recreational reservoir at Walailak University, Thailand. The organism was identified as A. triangularis using morphology and 18S rDNA nucleotide sequences. The pathogen was tested for their susceptibility to ethanol extracts of Thai medicinal plants based on eye infection treatment. The ethanol C. longa extract showed the strongest anti-Acanthamoeba activity against both the trophozoites and cysts, followed by Coscinium fenestratum, Coccinia grandis, and Acmella oleracea extracts, respectively. After 24 h, 95% reduction of trophozoite viability was significantly decreased following the treatment with C. longa extract at 125 µg/mL, compared with the control (P 
    Matched MeSH terms: Fresh Water/parasitology
  4. Entamoeba infections and associated risk factors among migrant workers in Peninsular Malaysia
    Sahimin N, Yunus MH, Douadi B, Yvonne Lim AL, Noordin R, Behnke JM, et al.
    Trop Biomed, 2019 Dec 01;36(4):1014-1026.
    PMID: 33597471
    The influx of low skilled migrant workers to Malaysia from low socio-economic countries where gastrointestinal parasitic infections are prevalent has raised concerns about transmission to the local population. Three methods for detection (serology, microscopy and molecular techniques) were utilized to identify Entamoeba infections amongst the targeted cohort and determine risk factors associated with infection. Serological screening of 484 migrant workers from five working sectors in Peninsular Malaysia using IgG4 ELISA based on the rPPDK antigen showed an overall seroprevalence of 7.4% (n = 36; CL95 = 5.3-10.1%) with only one factor statistically associated with seropositivity of anti-amoebic antibodies, i.e. years of residence in Malaysia (χ2 1 = 4.007, p = 0.045). Microscopic examination of 388 faecal samples for protozoan cysts and trophozoites showed a slightly higher prevalence (11.6%; n=45; CL95: 8.4-14.8%). Meanwhile, amplification of the 16S rDNA gene detected two species i.e. Entamoeba dispar (23/388; 5.9%; CL95: 3.6-8.3%) and E. histolytica (11/388; 2.8%; CL95: 1.2-4.5%) and mixed infections with both parasites in only three samples (3/388; 0.8%; CL95: 0.2-2.2%). Entamoeba dispar infection was significantly associated with those employed in food and domestic services (χ2 4 = 12.879, p = 0.012). However, none of the factors affected the prevalence of E. histolytica infection. Despite the low prevalence of E. histolytica in faecal samples of the study cohort, the presence of this pathogenic parasite still poses potential public health risks and calls for tighter control strategies based on better availability of chemotherapeutic treatment and accessibility to appropriate health education.
    Matched MeSH terms: Feces/parasitology
  5. Multidisciplinary biomarkers aggrieve morbidity in schistosomiasis
    Noha MA, Enas AE, Aly E, Mohamed AE
    Trop Biomed, 2019 Dec 01;36(4):833-844.
    PMID: 33597455
    BACKGROUND: Biomarkers by definition are measurable molecules that mark the evidence of certain pathological processes. Collaboration of various biomarkers influences morbidity of schsitosomiasis in Egypt.

    OBJECTIVES: To identify the biomarkers: CRP, IgE, hemoglobin, ferritin, vitamin D, and platelets in terms of relationship with active and chronic schistosomiasis; demographic data, and their interinfluence.

    STUDY DESIGN: A cross-sectional study.

    METHODS: Parasitological analysis of stool and urine samples, Indirect Hemagglutination Test, Enzyme linked Immunoassay, Hematology Analyzer, and Statistical Package SPSS (Statistical Package for the Social Sciences) version 25.

    RESULTS: Out of 400 participants, 25% suffered of schistosomiasis: active S. mansoni infections in 7 cases (1.75%), S. haematobium infections in 6 cases (1.5%), and chronic schistosomiasis infections in 20 cases (5%). Creactive protein (CRP) likewise IgE levels were higher in active S. mansoni and S. haematobium infections when compared with chronic schistosomiasis. IgE levels appeared to affect infection intensity in S. haematobium. Inversely, hemoglobin (Hb) values were low in active schistosomiasis and upgraded in chronic infection (*p<0.05). Ferritin levels varied in active Schistosoma infection and normalized during chronicity. Vitamin D was reduced in active and chronic schistosomiais. Platelet counts were within normal ranges throughout the study groups. Distribution of ferritin, vit D, and platelets was statistically insignificant among Schistosoma infected population. Age affected only hemoglobin, CRP, and IgE biomarkers. CRP and IgE were in direct relationship together and inversely proportional with hemoglobin (*P <0.05).

    CONCLUSION: Anemia increased proportionally with biomarkers of inflammatory stress (CRP and IgE) in early infections. Meanwhile, Hb and ferritin (iron stores) improved during chronicity. Hypovitaminosis-D associated the entire course of schistosomiasis while platelet counts were not affected.

    Matched MeSH terms: Anemia/parasitology
  6. Identification and characterization of Leishmania amastigote and axenic form antigens
    Abdelhaleem AA, Elamin EM, Bakheit SM, Mukhtar MM
    Trop Biomed, 2019 Dec 01;36(4):866-873.
    PMID: 33597459
    This study was aimed to identify and characterize Leishmania amastigote, and axenic form antigens. Two in vitro techniques were used to change leishmania parasite isolates from promastigote form to amastigotes and amastigote like (axenic) forms. The main strategy relied upon in vitro infection of murine macrophages cell line J774 with leishmania promastigote, at 37°C with 5% CO2, while the second technique relied upon the culture of promastigote at 37°C with low pH (5.5), and 5-10% CO2. Proteins were extracted and fractionated utilizing 12% Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS PAGE). Antigens were recognized using both immune dot blot and western blot procedures. PCR was performed for recognition of leishmania parasites in infected J774 macrophages. L. major was quicker in infectivity of macrophages cell line than L. donovani. Shared proteins ranging from 26-116 kDa were identified by SDS PAGE in all stages. Immune Dot-blot method showed positive outcomes, while western blot identified an exceptional antigen band of 16 kDa in amastigote, this unique band could be of value in diagnosis and vaccination of leishmaniasis. PCR results confirmed presence of both isolates demonstrating that coinfection is conceivable, and no indications of hereditary recombination at kinetoplast DNA (kDNA) were identified in macrophages simultaneously infected by L. major and L. donovani.
    Matched MeSH terms: Macrophages/parasitology*
  7. Fulltext Distribution and prevalence of malaria parasites among long-tailed macaques (Macaca fascicularis) in regional populations across Southeast Asia
    Zhang X, Kadir KA, Quintanilla-Zariñan LF, Villano J, Houghton P, Du H, et al.
    Malar J, 2016 09 02;15(1):450.
    PMID: 27590474 DOI: 10.1186/s12936-016-1494-0
    BACKGROUND: Plasmodium knowlesi and Plasmodium cynomolgi are two malaria parasites naturally transmissible between humans and wild macaque through mosquito vectors, while Plasmodium inui can be experimentally transmitted from macaques to humans. One of their major natural hosts, the long-tailed macaque (Macaca fascicularis), is host to two other species of Plasmodium (Plasmodium fieldi and Plasmodium coatneyi) and is widely distributed in Southeast Asia. This study aims to determine the distribution of wild macaques infected with malarial parasites by examining samples derived from seven populations in five countries across Southeast Asia.

    METHODS: Plasmodium knowlesi, P. cynomolgi, P. coatneyi, P. inui and P. fieldi, were detected using nested PCR assays in DNA samples from 276 wild-caught long-tailed macaques. These samples had been derived from macaques captured at seven locations, two each in the Philippines (n = 68) and Indonesia (n = 70), and one each in Cambodia (n = 54), Singapore (n = 40) and Laos (n = 44). The results were compared with previous studies of malaria parasites in long-tailed macaques from other locations in Southeast Asia. Fisher exact test and Chi square test were used to examine the geographic bias of the distribution of Plasmodium species in the macaque populations.

    RESULTS: Out of 276 samples tested, 177 were Plasmodium-positive, with P. cynomolgi being the most common and widely distributed among all long-tailed macaque populations (53.3 %) and occurring in all populations examined, followed by P. coatneyi (20.4 %), P. inui (12.3 %), P. fieldi (3.4 %) and P. knowlesi (0.4 %). One P. knowlesi infection was detected in a macaque from Laos, representing the first documented case of P. knowlesi in wildlife in Laos. Chi square test showed three of the five parasites (P. knowlesi, P. coatneyi, P. cynomolgi) with significant bias in prevalence towards macaques from Malaysian Borneo, Cambodia, and Southern Sumatra, respectively.

    CONCLUSIONS: The prevalence of malaria parasites, including those that are transmissible to humans, varied among all sampled regional populations of long-tailed macaques in Southeast Asia. The new discovery of P. knowlesi infection in Laos, and the high prevalence of P. cynomolgi infections in wild macaques in general, indicate the strong need of public advocacy in related countries.

    Matched MeSH terms: Malaria/parasitology
  8. Development of a thermostabilised triplex LAMP assay with dry-reagent four target lateral flow dipstick for detection of Entamoeba histolytica and non-pathogenic Entamoeba spp
    Foo PC, Chan YY, Mohamed M, Wong WK, Nurul Najian AB, Lim BH
    Anal Chim Acta, 2017 May 08;966:71-80.
    PMID: 28372729 DOI: 10.1016/j.aca.2017.02.019
    This study highlighted the development of a four target nitrocellulose-based nucleic acid lateral flow immunoassay biosensor in a dry-reagent strip format for interpretation of double-labelled double-stranded amplicons from thermostabilised triplex loop-mediated isothermal amplification assay. The DNA biosensor contained two test lines which captured biotin and texas red labelled amplicons; a LAMP internal amplification control line that captured digoxigenin labelled amplicon; and a chromatography control line that validated the functionality of the conjugated gold nanoparticles and membrane. The red lines on detection pad were generated when the gold nanoparticles conjugated antibody bound to the fluorescein labelled amplicons, and the capture agents bound to their specific hapten on the other 5' end of the double-stranded amplicon. The applicability of this DNA biosensor was demonstrated using amoebiasis-causing Entamoeba histolytica simultaneously with the non-pathogenic but morphologically identical Entamoeba dispar and Entamoeba moshkovskii. The biosensor detection limit was 10 E. histolytica trophozoites, and revealed 100% specificity when it was evaluated against 3 medically important Entamoeba species and 75 other pathogenic microorganisms. Heat stability test showed that the biosensor was stable for at least 181 days at ambient temperature. This ready-to-use and cold-chain-free biosensor facilitated the post-LAMP analysis based on visualisation of lines on strip instead of observation of amplicon patterns in agarose gel.
    Matched MeSH terms: Feces/parasitology
  9. Skin-piercing blood-sucking moths II: Studies on a further 3 adult Calyptra [Calpe] sp. (Lepid., Noctuidae)
    Bänziger H
    Acta Trop, 1979 Mar;36(1):23-37.
    PMID: 35931
    1. Of the scarce Calyptra minuticornis, C. orthograpta and C. labilis, 51, 24, and 7 adults, respectively, were observed during some 600 night inspections at over 100 sites in 1965--1967 and 1971--1977. 2. Hitherto biologically completely unknown, and not recorded before in S.E. Asia, the latter two species flew in or near tropical monsoon forests in hilly regions (300--600 m) of N. Thailand (C. orthograpta also N. Laos). C. minuticornis was found in these and in tropical evergreen and semi-evergreen rain forests of S. Thailand and N.W. Malaysia. 3. In N. Thailand the three species were more common at the end of the cool season/start of the hot season and at the start of the rainy season. They were active mainly during the first half of the night 4. Flight and piercing behaviour, alighting, resting, enemies, and the lack of females, were similar to virtually identical with the "classical" skin-piercing blood-sucking C. eustrigata. 5. C. labilis was seen attacking elephant, C. orthograpta also water buffalo and sambar, C. minuticornis also zebu and tapir but not sambar. C. minuticornis settled on man also but did not pierce. 6. Through no piercing of hosts' skin has actually been seen in nature, indirect evidence suggests that the 3 moths are likely to be occasional blood-suckers. They pierced and sucked blood from the author's skin in experiments. 7. Reasons for lack of direct evidence may be: less developed hematophagy, less favoured hosts, lack of easy-to-pierce injured skin (which also trigger the piercing response), different climatic and phytoecological environment, fewer specimens than in the case of C. eustrigata. 8. Field observations and experiments indicate that the closely related, fruit-piercing Oraesia emarginata is not skin-piercing blood-sucking--a habit likely to be exhibited mainly in humid equatorial regions by a few Calyptra only.
    Matched MeSH terms: Buffaloes/parasitology
  10. Parasite fauna of the house rat Rattus rattus diardii in Kuala Lumpur and nearby villages
    Leong Tak Seng, Lim Boo Liat, Yap LF, Krishnasamy M
    Southeast Asian J. Trop. Med. Public Health, 1979 Mar;10(1):122-6.
    PMID: 483007
    One hundred and fifty one house rats, Rattus rattus diardii from five different localities, Jinjang, Dato Keramat, Kuala Lumpur, Sungai Besi and Selayang Baru, were examined for parasites. Nineteen species of parasites were recovered. Hymenolepis diminuta and Nippostrongylus brasiliensis are the predominant species. The dominancy of the parasite species in the rats differed in each locality: Hymenolepis diminuta in Dato Keramat and Kuala Lumpur; Nippostrongylus brasiliensis in Sungai Besi; Gongylomena neoplasticum in Jinjang and Selayang Baru. The influences of human habitats on the parasite fauna of house rats are discussed.
    Matched MeSH terms: Rats/parasitology*
  11. Malaria of the orang-utan (Pongo pygmaeus) in Borneo
    Peters W
    Philos Trans R Soc Lond B Biol Sci, 1976 Sep 28;275(941):439-82.
    PMID: 10589
    The primary objective of this project was to study the life cycle and ecology of Plasmodium pitheci, a malaria parasite of the orang-utan. The field work was based on the orang-utan rehabilitation centre in the Sepilok Forest Reserve of eastern Sabah. Two visits were made to Sepilok, the first in February and March, 1972, and the second (by W.P.) in January 1974. On the first visit two species of "surrogate host" were taken to Sabah, i.e. chimpanzees and Aotus monkeys for experimental work. The arboreal habitat of the orang-utan in the dipterocarp forests of eastern Sabah is described. In the Sepilok Forest Reserve dwell gibbons and leaf-monkeys, in addition to a small population of semi-domesticated and wild, free-ranging orang-utans of various ages. Although numerous species of anopheline mosquitoes have been collected in eastern Sabah, longitudinal studies are not available. Anopheles balabacensis was caught both attracted to orang-utans and to man at Sepilok. This species which is the main vector of human malaria in the north of Borneo, is suspected also of transmitting orang-utan malaria in this part of Sabah. Repeated blood examinations have been made on a number of orang-utans in the centre since 1966 and a high prevalence of infection was recorded with Plasmodium pitheci. In 1966 10 out of 19 animals had demonstrable parasitaemia. Detailed case histories are presented to show the course of parasitaemia in several orang-utans. Infections of P. pitheci were found to run a very chronic course. During the 1972 expedition a second, previously undescribed malaria parasite of the orang-utan was discovered, and was named P. silvaticum. The new parasite was successfully transmitted both by blood inoculation and, later, by sporozoite inoculation, into splenectomized chimpanzees. Although both species of malaria parasite may cause transitory signs of illness, orang-utans in general appear to be little discomforted by the infection. The animals do however suffer from other infectious diseases such as amoebic and balantidial dysentery, and melioidosis is a serious natural hazard which may have accounted for several deaths of wild orang-utans. An unidentified, intraerythrocytic structure that appeared in the blood of one chimpanzee, which had been inoculated with blood from an orang-utan, may have contributed to its death. Detailed descriptions and illustrations of P. pitheci and P. silvaticum are given. All stages of the life cycle of P. silvaticum are known (the tissue stages having been described in the liver of a "surrogate host", the chimpanzee) but only the blood and sporogonic stages of P. pitheci have been seen. This species was not infective to a chimpanzee, although there is an earlier report of a transient infection in this host by other workers. In the blood both parasites showed a tertian periodicity. From the appearance of the tissue schizonts on the seventh day it was estimated that the complete pre-erythrocytic cycle of P. silvaticum in the chimpanzee would occupy 8 days. P...
    Matched MeSH terms: Hylobates/parasitology
  12. Angiostrongylus malaysiensis from Tuaran, Sabah, with reference to the distribution of the parasite in Malaysia
    Liat LB, Wah LT, Cheah W, Cheah W, Fong YL, Fong YL
    Southeast Asian J. Trop. Med. Public Health, 1976 Sep;7(3):384-9.
    PMID: 1030843
    A survey of Angiostrongylus malaysiensis among wild rodent and molluscan hosts was made in the Tuaran Central Agricultural Research Station and within the vicinity of Tuaran, Sabah. Three of 19 Rattus rattus diardii, one of 2 R. exulans and one R. argentiventer were found naturally infected with the parasite. In this survey 56 of 382 molluscs comprising of Pila scutata, Achatina fulica and two species of land slugs, Laevicaulis alte and Microparmarion malayanus, were found naturally infected with the parasite. Samples of larvae from each of these molluscs were experimentally transferred to laboratory albino rats and adult worms consistent with A. malaysiensis were recovered. Comparison of the rat hosts and the molluscan intermediate hosts of the parasite in Peninsular Malaysia, Sarawak and Sabah was made, and the finding of A. malaysiensis in Tuaran is the first report of the parasite from Sabah. The distribution of the parasite throughout Malaysia is discussed. Observation on the human consumption of the freshwater snail, P. scutata, was made. Although the infection rate of this snail is low compared with other molluscan hosts examined. The importance of this mollusc as a potential source of human infection should not be overlooked. Hospital records for 1974 and 1975 were examined and clinical human angiostrongyliasis was rarely recorded in Sabah.
    Matched MeSH terms: Snails/parasitology
  13. Increased frequency of chloroquine resistant P. falciparum on a rubber estate in Peninsular Malaysia during two years of systematic chloroquine treatment
    Dondero TJ, Parsons RE, O'Holohan DR
    Southeast Asian J. Trop. Med. Public Health, 1975 Dec;6(4):488-94.
    PMID: 775652
    Chloroquine pressure was applied over a 22 month period on a somewhat isolated, malarious rubber estate by examination of residents at 4-week intervals and treatment of parasitaemias with chloroquine. During this time the monthly attack rate for P. falciparum rose four-fold to an average of nearly 18% per month, while that of P. vivax remained relatively constant at about 8%. Eight in vivo chloroquine resistance studies, which allowed both detection of late recrudescing R-I resistance and estimation of the risk of reinfection, showed an apparent rise in the drug resistance rate, from 12% to 20% prior to the study to the range of 40-50%. Virtually all resistance encountered was R-I in nature. There was no convincing evidence of chloroquine resistance among 148 tested P. vivax infections.
    Matched MeSH terms: Blood/parasitology
  14. The problem of soil transmitted helminths in squatter areas around Kualalumpur
    Yan CW, Ishak F, Hee GL, Devaraj JM, Ismail K, Jalleh RP, et al.
    Med J Malaysia, 1978 Sep;33(1):34-43.
    PMID: 571513
    Matched MeSH terms: Feces/parasitology
  15. Fulltext Malaria parasites of long-tailed macaques in Sarawak, Malaysian Borneo: a novel species and demographic and evolutionary histories
    Nada Raja T, Hu TH, Zainudin R, Lee KS, Perkins SL, Singh B
    BMC Evol. Biol., 2018 04 10;18(1):49.
    PMID: 29636003 DOI: 10.1186/s12862-018-1170-9
    BACKGROUND: Non-human primates have long been identified to harbour different species of Plasmodium. Long-tailed macaques (Macaca fascicularis), in particular, are reservoirs for P. knowlesi, P. inui, P. cynomolgi, P. coatneyi and P. fieldi. A previous study conducted in Sarawak, Malaysian Borneo, however revealed that long-tailed macaques could potentially harbour novel species of Plasmodium based on sequences of small subunit ribosomal RNA and circumsporozoite genes. To further validate this finding, the mitochondrial genome and the apicoplast caseinolytic protease M genes of Plasmodium spp. were sequenced from 43 long-tailed macaque blood samples.

    RESULTS: Apart from several named species of malaria parasites, long-tailed macaques were found to be potentially infected with novel species of Plasmodium, namely one we refer to as "P. inui-like." This group of parasites bifurcated into two monophyletic clades indicating the presence of two distinct sub-populations. Further analyses, which relied on the assumption of strict co-phylogeny between hosts and parasites, estimated a population expansion event of between 150,000 to 250,000 years before present of one of these sub-populations that preceded that of the expansion of P. knowlesi. Furthermore, both sub-populations were found to have diverged from a common ancestor of P. inui approximately 1.5 million years ago. In addition, the phylogenetic analyses also demonstrated that long-tailed macaques are new hosts for P. simiovale.

    CONCLUSIONS: Malaria infections of long-tailed macaques of Sarawak, Malaysian Borneo are complex and include a novel species of Plasmodium that is phylogenetically distinct from P. inui. These macaques are new natural hosts of P. simiovale, a species previously described only in toque monkeys (Macaca sinica) in Sri Lanka. The results suggest that ecological factors could affect the evolution of malaria parasites.

    Matched MeSH terms: Malaria/parasitology*
  16. Genetic diversity in the C-terminus of merozoite surface protein 1 among Plasmodium knowlesi isolates from Selangor and Sabah Borneo, Malaysia
    Yap NJ, Goh XT, Koehler AV, William T, Yeo TW, Vythilingam I, et al.
    Infect Genet Evol, 2017 10;54:39-46.
    PMID: 28634105 DOI: 10.1016/j.meegid.2017.06.019
    Plasmodium knowlesi, a malaria parasite of macaques, has emerged as an important parasite of humans. Despite the significance of P. knowlesi malaria in parts of Southeast Asia, very little is known about the genetic variation in this parasite. Our aim here was to explore sequence variation in a molecule called the 42kDa merozoite surface protein-1 (MSP-1), which is found on the surface of blood stages of Plasmodium spp. and plays a key role in erythrocyte invasion. Several studies of P. falciparum have reported that the C-terminus (a 42kDa fragment) of merozoite surface protein-1 (MSP-142; consisting of MSP-119 and MSP-133) is a potential candidate for a malaria vaccine. However, to date, no study has yet investigated the sequence diversity of the gene encoding P. knowlesi MSP-142 (comprising Pk-msp-119 and Pk-msp-133) among isolates in Malaysia. The present study explored this aspect. Twelve P. knowlesi isolates were collected from patients from hospitals in Selangor and Sabah Borneo, Malaysia, between 2012 and 2014. The Pk-msp-142 gene was amplified by PCR and directly sequenced. Haplotype diversity (Hd) and nucleotide diversity (л) were studied among the isolates. There was relatively high genetic variation among P. knowlesi isolates; overall Hd and л were 1±0.034 and 0.01132±0.00124, respectively. A total of nine different haplotypes related to amino acid alterations at 13 positions, and the Pk-MSP-119 sequence was found to be more conserved than Pk-msp-133. We have found evidence for negative selection in Pk-msp-42 as well as the 33kDa and 19kDa fragments by comparing the rate of non-synonymous versus synonymous substitutions. Future investigations should study large numbers of samples from disparate geographical locations to critically assess whether this molecule might be a potential vaccine target for P. knowlesi.
    Matched MeSH terms: Malaria/parasitology*
  17. Hookworm infections among migrant workers in Malaysia: Molecular identification of Necator americanus and Ancylostoma duodenale
    Sahimin N, Lim YAL, Douadi B, Mohd Khalid MKN, Wilson JJ, Behnke JM, et al.
    Acta Trop, 2017 Sep;173:109-115.
    PMID: 28610937 DOI: 10.1016/j.actatropica.2017.06.011
    Ongoing urbanisation of the working population as well as cross-border migration of workers particularly into large cities has contributed to the development and growth of urban slums. These deprived areas are conducive for the transmission of intestinal pathogens including hookworm. The aim of this study was to determine both the prevalence and species identity of hookworm infections among the migrant worker community in Malaysia. A total of 388 faecal samples were collected from migrant workers between September 2014 and August 2015, representing workers from five employment sectors: construction, manufacturing, agriculture and plantations, food services and domestic services. Faecal samples were examined by microscopy and positive samples were subjected to molecular analysis. A total of 51 samples (13.1%) were positive by microscopy for hookworm infections. A two-step PCR based method amplifying a fragment of the 28S rRNA-ITS2 region was used to identify infections by Necator americanus and Ancylostoma spp. PCR products positive for Ancylostoma spp. were sequenced bidirectionally, and sequences analysed through BLAST and phylogenetic analysis. Samples containing Ancylostoma duodenale were further characterized by amplification and sequencing a fragment of cytochrome c oxidase subunit 1 (cox1) gene. PCR amplicons were successfully obtained from 42 (82.4%) of 51 samples, with 81.0% (34 of 42) identified as Necator americanus, 16.7% (7 of 42) as Ancylostoma spp. and 2.4% (1 of 42) as mixed infections of both species. All eight Ancylostoma spp. were confirmed to be Ancylostoma duodenale and this is the first time A. duodenale was reported in Malaysia. Samples containing A. duodenale from Nepalese and Indonesian workers shared high-similarity and were distinct compared to sequences from other countries. This study highlights the prevalence of hookworm infections among migrant workers living in Malaysia. Our findings underscore the necessity of screening migrant workers for hookworm infections, particularly those working in food-related services and industries.
    Matched MeSH terms: Hookworm Infections/parasitology*
  18. Fulltext Development of Loop-Mediated Isothermal Amplification-Based Lateral Flow Device Method for the Detection of Malaria
    Mallepaddi PC, Lai MY, Podha S, Ooi CH, Liew JW, Polavarapu R, et al.
    Am J Trop Med Hyg, 2018 09;99(3):704-708.
    PMID: 29943720 DOI: 10.4269/ajtmh.18-0177
    The present study aims to develop a method for rapid diagnosis of malaria using loop-mediated isothermal amplification (LAMP) combined with a lateral flow device (LFD). By adding the biotin-labeled and fluorescein amidite-labeled loop primers to the LAMP reaction solution, the end product can be visualized on a LFD. The entire procedure takes approximately 42 minutes to complete, LAMP assay exhibited high sensitivity, as the detection limit was 0.01 pg/μL for all five Plasmodium species. It was demonstrated that all Plasmodium knowlesi (N = 90) and Plasmodium vivax (N = 56) were positively amplified by LAMP-LFD assay, whereas healthy donor samples (N = 8) were negative. However, not all mixed infections were positive, and other infected nonmalaria samples were negative. Loop-mediated isothermal amplification-LFD represents a robust approach with potential suitability for use in resource-constrained laboratories. We believe that LAMP-LFD has a potential to be developed as point-of-care diagnostic tool in future.
    Matched MeSH terms: Malaria/parasitology*
  19. Fulltext In vitro invasion inhibition assay using antibodies against Plasmodium knowlesi Duffy binding protein alpha and apical membrane antigen protein 1 in human erythrocyte-adapted P. knowlesi A1-H.1 strain
    Muh F, Lee SK, Hoque MR, Han JH, Park JH, Firdaus ER, et al.
    Malar J, 2018 Jul 27;17(1):272.
    PMID: 30049277 DOI: 10.1186/s12936-018-2420-4
    BACKGROUND: The rapid process of malaria erythrocyte invasion involves ligand-receptor interactions. Inducing antibodies against specific ligands or receptors that abrogate the invasion process is a key challenge for blood stage vaccine development. However, few candidates were reported and remain to be validated for the discovery of new vaccine candidates in Plasmodium knowlesi.

    METHODS: In order to investigate the efficacy of pre-clinical vaccine candidates in P. knowlesi-infected human cases, this study describes an in vitro invasion inhibition assay, using a P. knowlesi strain adapted to in vitro growth in human erythrocytes, PkA1-H.1. Recombinant proteins of P. knowlesi Duffy binding protein alpha (PkDBPα) and apical membrane antigen 1 (PkAMA1) were produced in Escherichia coli system and rabbit antibodies were generated from immune animals.

    RESULTS: PkDBPα and PkAMA1 recombinant proteins were expressed as insoluble and produced as a functional refolded form for this study. Antibodies against PkDBPα and PkAMA1 specifically recognized recombinant proteins and native parasite proteins in schizont-stage parasites on the merozoite organelles. Single and combination of anti-PkDBPα and anti-PkAMA1 antibodies elicited strong growth inhibitory effects on the parasite in concentration-dependent manner. Meanwhile, IgG prevalence of PkDBPα and PkAMA1 were observed in 13.0 and 46.7% in human clinical patients, respectively.

    CONCLUSION: These data provide support for the validation of in vitro growth inhibition assay using antibodies of DBPα and AMA1 in human-adapted P. knowlesi parasite PkA1-H.1 strain.

    Matched MeSH terms: Erythrocytes/parasitology*
  20. Genomic evaluations of Wolbachia and mtDNA in the population of coconut hispine beetle, Brontispa longissima (Coleoptera: Chrysomelidae)
    Ali H, Muhammad A, Bala NS, Wang G, Chen Z, Peng Z, et al.
    Mol Phylogenet Evol, 2018 10;127:1000-1009.
    PMID: 29981933 DOI: 10.1016/j.ympev.2018.07.003
    Wolbachia pipientis is a diverse, ubiquitous and most prevalent intracellular bacterial group of alpha-Proteobacteria that is concerned with many biological processes in arthropods. The coconut hispine beetle (CHB), Brontispa longissima (Gestro) is an economically important pest of palm cultivation worldwide. In the present study, we comprehensively surveyed the Wolbachia-infection prevalence and mitochondrial DNA (mtDNA) polymorphism in CHB from five different geographical locations, including China's Mainland and Taiwan, Vietnam, Thailand, Malaysia and Indonesia. A total of 540 sequences were screened in this study through three different genes, i.e., cytochrome oxidase subunit I (COI), Wolbachia outer surface protein (wsp) and multilocus sequencing type (MLST) genes. The COI genetic divergence ranges from 0.08% to 0.67%, and likewise, a significant genetic diversity (π = 0.00082; P = 0.049) was noted within and between all analyzed samples. In the meantime, ten different haplotypes (H) were characterized (haplotype diversity = 0.4379) from 21 different locations, and among them, H6 (46 individuals) have shown a maximum number of population clusters than others. Subsequently, Wolbachia-prevalence results indicated that all tested specimens of CHB were found positive (100%), which suggested that CHB was naturally infected with Wolbachia. Wolbachia sequence results (wsp gene) revealed a high level of nucleotide diversity (π = 0.00047) under Tajima's D test (P = 0.049). Meanwhile, the same trend of nucleotide diversity (π = 0.00041) was observed in Wolbachia concatenated MLST locus. Furthermore, phylogenetic analysis (wsp and concatenated MLST genes) revealed that all collected samples of CHB attributed to same Wolbachia B-supergroup. Our results strongly suggest that Wolbachia bacteria and mtDNA were highly concordant with each other and Wolbachia can affect the genetic structure and diversity within the CHB populations.
    Matched MeSH terms: Cocos/parasitology*
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