Displaying publications 141 - 160 of 164 in total

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  1. Cheong FW, Fong MY, Lau YL
    Acta Trop, 2016 Feb;154:89-94.
    PMID: 26624919 DOI: 10.1016/j.actatropica.2015.11.005
    Plasmodium knowlesi can cause potentially life threatening human malaria. The Plasmodium merozoite surface protein-142 (MSP-142) is a potential target for malaria blood stage vaccine, and for diagnosis of malaria. Two epitope mapping techniques were used to identify the potential epitopes within P. knowlesi MSP-142. Nine and 14 potential epitopes were identified using overlapping synthetic peptide library and phage display library, respectively. Two regions on P. knowlesi MSP-142 (amino acid residues 37-95 and residues 240-289) were identified to be the potential dominant epitope regions. Two of the prominent epitopes, P10 (TAKDGMEYYNKMGELYKQ) and P31 (RCLLGFKEVGGKCVPASI), were evaluated using mouse model. P10- and P31-immunized mouse sera reacted with recombinant P. knowlesi MSP-142, with the IgG isotype distribution of IgG2b>IgG1>IgG2a>IgG3. Significant higher level of cytokines interferon-gamma and interleukin-2 was detected in P31-immunized mice. Both P10 and P31 could be the suitable epitope candidates to be used in malaria vaccine designs and immunodiagnostic assays, provided further evaluation is needed to validate the potential uses of these epitopes.
  2. Cheong FW, Dzul S, Fong MY, Lau YL, Ponnampalavanar S
    Acta Trop, 2020 Jun;206:105454.
    PMID: 32205132 DOI: 10.1016/j.actatropica.2020.105454
    Transmission of Plasmodium vivax still persist in Malaysia despite the government's aim to eliminate malaria in 2020. High treatment failure rate of chloroquine monotherapy was reported recently. Hence, parasite drug susceptibility should be kept under close monitoring. Mutation analysis of the drug resistance markers is useful for reconnaissance of anti-malarial drug resistance. Hitherto, information on P. vivax drug resistance marker in Malaysia are limited. This study aims to evaluate the mutations in four P. vivax drug resistance markers pvcrt-o (putative), pvmdr1 (putative), pvdhfr and pvdhps in 44 isolates from Malaysia. Finding indicates that 27.3%, 100%, 47.7%, and 27.3% of the isolates were carrying mutant allele in pvcrt-o, pvmdr1, pvdhfr and pvdhps genes, respectively. Most of the mutant isolates had multiple point mutations rather than single point mutation in pvmdr1 (41/44) and pvdhfr (19/21). One novel point mutation V111I was detected in pvdhfr. Allelic combination analysis shows significant strong association between mutations in pvcrt-o and pvmdr1 (X2 = 9.521, P < 0.05). In the present study, 65.9% of the patients are non-Malaysians, with few of them arrived in Malaysia 1-2 weeks before the onset of clinical manifestations, or had previous history of malaria infection. Besides, few Malaysian patients had travel history to vivax-endemic countries, suggesting that these patients might have acquired the infections during their travel. All these possible imported cases could have placed Malaysia in a risk to have local transmission or outbreak of malaria. Six isolates were found to have mutations in all four drug resistance markers, suggesting that the multiple-drugs resistant P. vivax strains are circulating in Malaysia.
  3. Chan LL, Mak JW, Low YT, Koh TT, Ithoi I, Mohamed SM
    Acta Trop, 2011 Jan;117(1):23-30.
    PMID: 20858455 DOI: 10.1016/j.actatropica.2010.09.004
    During a study on the quality of the indoor environment, Acanthamoeba spp. were detected in 20 out of 87 dust samples collected from air-conditioners installed in a four-story campus building located in Kuala Lumpur, Malaysia. Twenty-one cloned Acanthamoeba isolates designated as IMU1 to IMU21 were established from the positive primary cultures. Five species were identified from the 16 isolates according to the morphological criteria of Pussard and Pons; i.e. A. castellanii, A. culbertsoni, A. griffini, A. hatchetti and A. polyphaga. Species identities for the remaining five isolates (IMU4, IMU5, IMU15, IMU20 and IMU21), however, could not be determined morphologically. At genotypic characterization, these isolates were placed into T3 (IMU14); T5 (IMU16 and IMU17) and T4 (all the remaining isolates). To predict the potential pathogenicity of these Acanthamoeba isolates, thermo- and osmotolerance tests were employed; many isolates were predicted as potential human pathogens based on the outcome of these tests. This is the first time potentially pathogenic Acanthamoeba have been isolated from air-conditioners in Malaysia.
  4. Chan LL, Toh HC, Jaikwang K, Loo EM, Wong JH, Liew YK, et al.
    Acta Trop, 2022 Feb 16.
    PMID: 35182491 DOI: 10.1016/j.actatropica.2022.106372
    Pathogenic Acanthamoeba species are the causative agents of Acanthamoeba keratitis and granulomatous amoebic encephalitis. Members of this amoeba genus are ubiquitous in the environments. In Malaysia, most environmental studies performed to date have targeted the detection and characterisation of Acanthamoeba sp. in different water sources, dust and soil samples collected near human habitats. However, no local study has yet to examine these amoebae in a forest, an isolated terrestrial environment, where human activity is relatively scarce. Further, there are also limited studies to investigate the same globally. The current study reported the isolation, morphological and genotypic characterisations of eleven Acanthamoeba sp. isolated from soils of the Payeh Maga Highland forest, Sarawak, Malaysia. Morphological analysis revealed that nine isolates belonged to Group II, whereas two isolates belonged to Group III as defined by the criteria of Pussard and Pons. The phylogenetic analysis based on complete 18S rRNA gene sequences showed that the isolates belonged to the rare T1 (six isolates), T6 (two isolates) and T13 (three isolates) genotypes. To the best of our knowledge, this is the first report about the detection of T6 Acanthamoeba sp. in this country. Overall, the current findings have enriched the knowledge pertaining to the occurrence, morphological and genotypic characteristics of Acanthamoeba sp. in an isolated terrestrial environment of Malaysia.
  5. 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.
  6. Bänziger H
    Acta Trop, 1975;32(2):125-44.
    PMID: 240258
    The Noctuid Calpe [Calyptral] eustrigata Hmps. was reported as a skin-piercing blood-sucking moth for the first time in Malaya (Bänziger, 1968) and is so far the only lepidopteran proved to suck blood by means of a piercing act. A few field observations and the description of the piercing behaviour of caged moths were given. Apart from a taxonomic study of the genus Calpe (Berio, 1956), a single record (Büttiker, 1969) and some notes on the moth's proboscis and possible evolutionary pathway (Bänziger, 1970, 1971, 1972) to our knowledge no other data have been published on the moth after its description as a new species (Hampson, 1926). The life cycle is completely unknown. From the scanty museum specimens available, it appears that the species inhabits South and Southeast Asia. A closely related, though less rare species, the fruit-piercing C. thalictri Bkh., has been used for a detailed study of the piercing mechanism likely to be adopted by Calpe (Bänziger, 1970); the feeding turned out to be as unusual as the feeding habits. Little or nothing is known about other Calpe species. C. eustrigata is not the only adult lepidopterous parasite of mammals. Lachryphagous ("eye-frequenting") moths feed as "marginal" parasites upon eye-secretions of ungulates, elephants and occasionally man (Shannon, 1928; Reid, 1954; Büttiker, 1964, 1967; Bänziger, 1966). Arcyophora species and the eulachryphagous Noctuid Lobocraspis graseifusa Hmps. which apparently feeds exclusively upon eye discharges, are suspected as vectors of eye diseases (Guilbride et al., 1959, Büttiker, 1964; Bänziger, 1972). While no lachryphagous moth is able to suck blood by a piercing act, there are a number of facultative lachryphagous moths which lick up the blood freely present at wounds, or that excreted anally by mosquitoes (Bänziger, 1969, 1972). Because of the scientific interest in C. eustrigata, research has been carried out to investigate different biological aspects of the species in Malaysia, Thailand. Laos and Indonesia (May 1971-May 1973). The first account presented here will be continued with a paper (in prep.) on the piercing mechanism and soon, it is hoped, with more information on the physiology, life cycle and medical importance of the moth.
  7. Braima KA, Muslimin M, M Ghazali AR, Wan-Nor F, Wilson JJ, Jeffery J, et al.
    Acta Trop, 2017 Jul;171:138-140.
    PMID: 28359829 DOI: 10.1016/j.actatropica.2017.03.025
    Mosquitoes are vectors of various human diseases in the tropics including yellow fever, dengue, malaria and West Nile virus. Mosquitoes can act as vectors between wildlife and humans, which is particularly important for diseases where wild animals serve as reservoirs of parasites in the absence of human infections. Research has mainly focused on the medical impacts of Anopheles, Aedes, Mansonia and Culex, however, very little attention has been directed towards other mosquito genera, especially those which act as vectors of diseases of wildlife. We have observed adults of Mimomyia (Etorleptiomyia) luzonensis (Ludlow, 1905) feeding on a toad, Ingerophrynus parvus, near an oil palm plantation settlement in Setia Alam, Selangor state, Peninsular Malaysia. Mimomyia is known to feed on reptiles and amphibians, and is a documented vector of several arboviruses, including West Nile virus. The observation of Mimomyia feeding on a common toad near a human settlement highlights a need to understand the relationships between mosquitoes, toads and humans from an ecological perspective. We report on-site observations of the feeding habit of Mimomyia; the first records from Malaysia.
  8. Benacer D, Thong KL, Min NC, Bin Verasahib K, Galloway RL, Hartskeerl RA, et al.
    Acta Trop, 2016 May;157:162-8.
    PMID: 26844370 DOI: 10.1016/j.actatropica.2016.01.031
    Leptospirosis is an emerging disease, especially in countries with a tropical climate such as Malaysia. A dramatic increase in the number of cases has been reported over the last decade; however, information on the epidemiological trends of this disease is lacking. The objective of this study is to provide an epidemiological description of human leptospirosis cases over a 9-year period (2004-2012) and disease relationship with meteorological, geographical, and demographical information. A retrospective study was undertaken to describe the patterns of human leptospirosis cases and their association with intrinsic (sex, age, and ethnicity) and extrinsic (location, rainfall, and temperature) factors. Data was grouped according to age, sex, ethnicity, seasonality and geographical distribution, and analyzed using statistical tools to understand the influence of all the different factors on disease incidence. A total of 12,325 cases of leptospirosis were reported between 2004 and 2012 with an upward trend in disease incidence, with the highest in 2012. Three hundred thirty-eight deaths were reported with an overall case fatality rate of 2.74%, with higher incidence in males (9696; 78.7%) compared with female patients (2629; 21.3%), and overall male to female ratio of 3.69:1. Patients aged cohorts between 30-39 years old (16.22 per 100,000 population) had the highest disease incidence while the lowest incidence occurred between <1 to 9 years old (3.44 per 100,000 population). The average incidence was highest amongst Malays (10.97 per 100,000 population), followed by Indians (7.95 per 100,000 population). Stratification according to geographical distribution showed that the state of Malacca had the highest average disease incidence (11.12 per 100,000 population) followed by Pahang (10.08 per 100,000 population). The states of Terengganu, Kelantan, and Perak recorded similar rates of incidence (≈8.00 per 100,000 population), while Johor with the least number of reported cases (1.80 per 100,000 population). Positive relationships were recorded between the number of reported cases with the number of raining days per month and monthly average temperature (p-value<0.05). However, no significant association was noted between rainfall volume and number of reported Leptospirosis cases. This collaborative efforts between medical, academic and governmental institutions has enabled the construction of this comprehensive database that is essential to understand the disease trends in Malaysia and add insights into the prevention and control of this disease.
  9. Basher MHA, Ithoi I, Mahmud R, Abdulsalam AM, Foead AI, Dawaki S, et al.
    Acta Trop, 2018 Feb;178:219-228.
    PMID: 29203378 DOI: 10.1016/j.actatropica.2017.11.015
    Acanthamoeba species are ubiquitous free-living protozoa that can be found worldwide. Occasionally, it can become parasitic and the causative agent of acanthamoebic keratitis (AK) and Granulomatous Amoebic Encephalitis (GAE) in man. A total of 160 environmental samples and 225 naturally-infected animal corneal swabs were collected for Acanthamoeba cultivation. Acanthamoeba was found to be high in samples collected from environments (85%, 136/160) compared to infected animal corneas (24.89%, 56/225) by microscopic examination. Analysis of nucleotide sequence of 18S rRNA gene of all the 192 cultivable Acanthamoeba isolates revealed 4 genotypes (T3, T4. T5 and T15) with T4 as the most prevalent (69.27%, 133/192) followed by T5 (20.31%), T15 (9.90%) and T3 (0.52%). Genotype T4 was from the strain of A. castellanii U07401 (44.27%), A. castellanii U07409 (20.83%) and A. polyphagaAY026243 (4.17%), but interestingly, only A. castellanii U07401 was detected in naturally infected corneal samples. In environmental samples, T4 was commonly detected in all samples including dry soil, dust, wet debris, wet soil and water. Among the T4, A. castellanii (U07409) strains were detected high occurrence in dry (45%) followed by aquatic (32.50%) and moist (22.50%) samples but however A. castellanii (U07401) strains were dominant in dry samples of soil and dust (93.10%). Subsequently, genotype T5 of A. lenticulata (U94741) strains were dominant in samples collected from aquatic environments (58.97%). In summary, A. castellanii (U07401) strains were found dominant in both environmental and corneal swab samples. Therefore, these strains are possibly the most virulent and dry soil or dusts are the most possible source of Acanthamoeba infection in cats and dogs corneas.
  10. Bamaga OA, Mahdy MA, Lim YA
    Acta Trop, 2015 Sep;149:59-63.
    PMID: 26001972 DOI: 10.1016/j.actatropica.2015.05.013
    Malaria is still a major public health problem in Yemen. More than 95% of the malaria cases are due to Plasmodium ‎falciparum‎. Recently in Yemen, the antimalarial treatment policy was changed from chloroquine (CQ) to artemisinin combination therapy (ACTs). However, CQ is still available and prescribed in the Yemeni market. The persistence of CQ resistance will be prolonged if the shift to ACT and the simultaneous withdrawal of CQ are not rigorously implemented. The aim of the current survey is to detect chloroquine-resistant mutations in P. falciparum chloroquine-resistance transporter (pfcrt) and P. falciparum multi-drug resistance-1 (pfmdr1) genes. These data will be important for future monitoring and assessment of antimalarial drug policy in Yemen. Blood specimens were collected from 735 individuals from different districts of the Hadhramout province, Yemen by house-to-house visit. Mutation-specific nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) methods were used to investigate the mutations in the pfmdr1(codons 86 and 1246) and pfcrt (codons 76, 271, 326, 356 and 371) genes. The overall prevalence of pfcrt mutations at codons 76, 271, 326 and 371 were 50.4%, 58.7%, 54.3% and 44.9%, respectively. All isolates had wild-type pfcrt 356 allele. The majority of pfmdr1 86 alleles (83.3%) and all pfmdr1 1246 alleles were wild type. There was no association between pfcrt mutations and symptomatology, gender and age groups. In conclusion, point mutations in codons 76, 271, 326 and 371 of pfcrt of P. falciparum are high suggesting a sustained high CQ resistance even after 4 years of shifting to ACTs. These findings warrant complete withdrawal of CQ use from the Yemeni market for P. falciparum and careful usage of CQ for treating Plasmodium vivax.
  11. Balachandra D, Rahumatullah A, Lim TS, Mustafa FH, Ahmad H, Anuar NS, et al.
    Acta Trop, 2021 Sep;221:105986.
    PMID: 34058161 DOI: 10.1016/j.actatropica.2021.105986
    Serodiagnosis is an essential component of the laboratory diagnosis of Strongyloides infection and is usually performed using an indirect IgG antibody test. A direct antigen detection method can complement the IgG assay, particularly for detecting early infection and post-treatment follow-up. In the present study, a recombinant scFv monoclonal antibody against NIE recombinant protein (rMAb23) that we had previously produced was used to develop a Strongyloides antigen detection ELISA (SsAg-ELISA). The assay is based on detecting immune complexes of circulating NIE antigens bound to Strongyloides-specific IgG antibodies. The optimized ELISA parameters were 10 µg/mL of rMAb23 coated on microtitre plate wells, 2% skim milk as blocking reagent, 1:100 serum dilution, and 1:1000 goat anti-human IgG F(ab')2 conjugated to horseradish peroxidase. Four groups of serum samples were used, i.e., Strongyloides-positive serum samples categorized into Groups IA and IB; the former were from probable chronic infections and the latter from probable early/acute infections. Strongyloides-negative samples comprising Groups II (healthy samples) and III (other infections); the latter were from eleven different types of other parasitic infections. The receiver operating characteristic (ROC) curve showed an area under the curve (AUC) of 1.00, cut-off optical density (OD405) of 0.5002, and 100% diagnostic sensitivity and specificity. The results of the commercial IgG-ELISA and SsAg-ELISA from Group IA were found to be moderately correlated (r = 0.416; p 
  12. Azhari NN, Ramli SNA, Joseph N, Philip N, Mustapha NF, Ishak SN, et al.
    Acta Trop, 2018 Dec;188:68-77.
    PMID: 30145261 DOI: 10.1016/j.actatropica.2018.08.020
    Leptospirosis is caused by the spirochetal bacterium Leptospira of which rodents are considered the most important reservoir. This study aims to determine and characterize virulent Leptospira species among rodents and small mammals found in human settlements and recreational spots within the Hulu Langat and Gombak districts of Selangor, Malaysia; regions that frequently report probable human leptospirosis cases. Molecular analysis revealed an overall Leptospira detection rate of 14.3% among the 266 small mammals captured, and the human settlements were found to have the highest number of isolates (15.1%), followed by recreational sites (14.5%). The molecular characterization conducted based on the lipL32, secY genes and MLST revealed that the strains belonged to four different species, including; Leptospira interrogans (29; 76.3%; ST50, ST238, ST243), L. kirschneri (5; 13.15%; ST110), L. borgpetersenii (3; 8%; ST143) and L. weilii (1; 2.63%; ST242). The study revealed genotypes of circulating strains among small mammals in Malaysia, which include Leptospira locus ST110 L. kirschneri, ST 50 L. interrogans, ST143 L. borgpetersenii and ST242 L. weilii. Among the small mammals studied, 17/105 (16.2%) Rattus norvegicus, 7/59 (11.9%) of Rattus rattus, 5/24 (20.8%) of Maxomys whiteheadi, 4/18 (22.2%) of Sundamys muelleri, 2/22 (9%), Tupaia gliss, 2/16 (12.5%) Rattus tiomanicus and 1/4 (25%) of Suncus murinus carried pathogenic leptospires. The data from the present study may imply that, in addition to rodents, other small mammals also serve as maintenance hosts for Leptospira. Hence, much remains unknown about Leptospira maintenance hosts, and there is need for further investigation to ascertain the prevailing serovars of pathogenic Leptospira in Malaysia. This will assist in the development of efficient diagnostic assays with improved microscopic agglutination test (MAT) panels, and in the implementation of suitable prevention and control measures.
  13. Aupalee K, Saeung A, Srisuka W, Fukuda M, Junkum A, Pitasawat B, et al.
    Acta Trop, 2020 Nov;211:105625.
    PMID: 32649996 DOI: 10.1016/j.actatropica.2020.105625
    Three new species of black flies from Thailand, Simulium wangkwaiense, S. tadtonense and S. maeklongkeense, are described based on their adults, pupal exuviae and cocoons. All three new species are assigned to the Simulium (Simulium) striatum species-group, bringing its total number in Thailand to seven. Simulium wangkwaiense sp. nov. is the species formerly called S. quinquestriatum in Thailand. Certain male and pupal morphological characteristics are shown to separate all seven Thai species of this species-group. All of the three new species have been analyzed genetically for their phylogenetic relationships, with three known related species (except for S. thailandicum), by using the fast-evolving nuclear big zinc finger (BZF) gene.
  14. Archibald CP, Mak JW, Mathias RG, Selvajothi S
    Acta Trop, 1990 Dec;48(2):149-57.
    PMID: 1980570
    Indirect fluorescent antibody (IFA) tests and enzyme-linked immunosorbent assays (ELISA) were used to measure antibodies to Plasmodium falciparum in an indigenous population in an area of Malaysia with high malaria prevalence. The results of three surveys were analyzed to examine the relation of these serologic measures with age, parasite rate, and spleen size. For children 0-4 years old, increasing spleen size was associated with an increasing likelihood of malaria parasitemia, while for 5-9 year olds the two variables were unrelated. Parasite rate declined with age and ELISA titre increased with age in all surveys; IFA titre was consistently high and did not vary with age. Neither antibody measure was significantly correlated with either the presence or the actual density of parasitemia. These antibody measures are most useful as adjuncts to the more traditional techniques of malaria assessment.
  15. Antinori S, Galimberti L, Milazzo L, Corbellino M
    Acta Trop, 2013 Feb;125(2):191-201.
    PMID: 23088834 DOI: 10.1016/j.actatropica.2012.10.008
    Plasmodium knowlesi was initially identified in the 30s as a natural Plasmodium of Macaca fascicularis monkey also capable of experimentally infecting humans. It gained a relative notoriety in the mid-30s as an alternative to Plasmodium vivax in the treatment of the general paralysis of the insane (neurosyphilis). In 1965 the first natural human infection was described in a US military surveyor coming back from the Pahang jungle of the Malaysian peninsula. P. knowlesi was again brought to the attention of the medical community when in 2004, Balbir Singh and his co-workers reported that about 58% of malaria cases observed in the Kapit district of the Malaysian Borneo were actually caused by P. knowlesi. In the following years several reports showed that P. knowlesi is much more widespread than initially thought with cases reported across Southeast Asia. This infection should also be considered in the differential diagnosis of any febrile travellers coming back from a recent travel to forested areas of Southeast Asia. P. knowlesi can cause severe malaria with a rate of 6-9% and with a case fatality rate of 3%. Respiratory distress, acute renal failure, shock and hyperbilirubinemia are the most frequently observed complications of severe P. knowlesi malaria. Chloroquine is considered the treatment of choice of uncomplicated malaria caused by P. knowlesi.
  16. Amir A, Shahari S, Liew JWK, de Silva JR, Khan MB, Lai MY, et al.
    Acta Trop, 2020 Nov;211:105596.
    PMID: 32589995 DOI: 10.1016/j.actatropica.2020.105596
    Zoonotic cases of Plasmodium knowlesi account for most malaria cases in Malaysia, and humans infected with P. cynomolgi, another parasite of macaques have recently been reported in Sarawak. To date the epidemiology of malaria in its natural Macaca reservoir hosts remains little investigated. In this study we surveyed the prevalence of simian malaria in wild macaques of three states in Peninsular Malaysia, namely Pahang, Perak and Johor using blood samples from 103 wild macaques (collected by the Department of Wildlife and National Parks Peninsular Malaysia) subjected to microscopic examination and nested PCR targeting the Plasmodium small subunit ribosomal RNA gene. As expected, PCR analysis yielded significantly higher prevalence (64/103) as compared to microscopic examination (27/103). No relationship between the age and/or sex of the macaques with the parasitaemia and the Plasmodium species infecting the macaques could be identified. Wild macaques in Pahang had the highest prevalence of Plasmodium parasites (89.7%), followed by those of Perak (69.2%) and Johor (28.9%). Plasmodium inui and P. cynomolgi were the two most prevalent species infecting the macaques from all three states. Half of the macaques (33/64) harboured two or more Plasmodium species. These data provide a baseline survey, which should be extended by further longitudinal investigations that should be associated with studies on the bionomics of the anopheline vectors. This information will allow an accurate evaluation of the risk of zoonotic transmission to humans, and to elaborate effective strategies to control simian malaria.
  17. Alareqi LMQ, Mahdy MAK, Lau YL, Fong MY, Abdul-Ghani R, Mahmud R
    Acta Trop, 2016 Oct;162:174-179.
    PMID: 27343362 DOI: 10.1016/j.actatropica.2016.06.016
    Since 2005, artesunate (AS) plus sulfadoxine/pyrimethamine (SP) combination has been adopted as the first-line treatment for uncomplicated malaria in Yemen in response to the high level of Plasmodium falciparum resistance to chloroquine (CQ). Therefore, the aim of the present study was to determine the frequency distribution of molecular markers associated with resistance to CQ and AS plus SP combination among P. falciparum isolates from a malaria-endemic area in Taiz governorate, Yemen. Fifty P. falciparum isolates were collected during a cross-sectional study in Mawza district, Taiz, in the period from October 2013 to April 2014. The isolates were investigated for drug resistance-associated molecular markers in five genes, including P. falciparum CQ resistance transporter (pfcrt) 76T and P. falciparum multidrug resistance 1 (pfmdr1) 86Y as markers of resistance to CQ, mutations in the Kelch 13 (K13) propeller domain for resistance to AS, and P. falciparum dihydrofolate reductase (pfdhfr) and P. falciparum dihydropteroate synthase (pfdhps) genes for resistance to SP. Nested polymerase chain reaction was used to amplify target genes in DNA extracts of the isolates followed by restriction fragment length polymorphism for detecting 76T and 86Y mutations in pfcrt and pfmdr1, respectively, and by DNA sequencing for detecting mutations in K13, pfdhfr and pfdhps. All the investigated isolates from Mawza district were harboring the pfcrt 76T mutant and the pfmdr1 N86 wild-type alleles. The pfdhfr 51I/108N double mutant allele was found in 2.2% (1/45) of the isolates; however, no mutations were detected at codons 436, 437, 540, 581 and 613 of pfdhps. All P. falciparum isolates that were successfully sequenced (n=47) showed the K13 Y493, R539, I543 and C580 wild-type alleles. In conclusion, the pfcrt 76T mutant allele is fixed in the study area about six years after the official withdrawal of CQ, possibly indicating its over-the-counter availability and continued use as a self-medication in the study area. However, the almost predominant wild-type alleles of the genes associated with resistance to AS and SP among P. falciparum isolates in the present study indicates the sustained efficacy of the currently adopted first-line treatment of AS plus SP in the study area.
  18. Alam MT, Das MK, Ansari MA, Sharma YD
    Acta Trop, 2006 Jan;97(1):10-8.
    PMID: 16125659
    Anopheles (Cellia) sundaicus (Rodenwaldt) is an important malaria vector in the Andaman and Nicobar islands of India where it breeds in freshwater as well as in brackish water. To establish the molecular identity of An. sundaicus on these islands we analyzed samples from four geographically isolated areas-Teressa, Nancowry, Car Nicobar and Katchal islands. PCR-amplification and nucleotide sequence analysis were performed for internal transcribed spacer 2 (ITS2) and domain-3 (D3) of 28S rRNA. The ITS2 region of An. sundaicus from all four islands was identical but different from An. sundaicus A of Vietnam and An. sundaicus s.s of Malaysia. Furthermore, freshwater and brackish water forms of An. sundaicus did not reveal any sequence variation. Similarly, the D3 sequences were identical among all An. sundaicus samples from the four islands. D3 sequences for a species of the Sundaicus Complex are reported here for the first time and thus could not be compared with other regional isolates of this species. In conclusion, probably only one member of the Sundaicus Complex exists on the Andaman and Nicobar islands, which breeds in freshwater as well as in brackish water and is different from the An. sundaicus A and Malaysian An. sundaicus s.s. The identification of a new sibling species of the Sundaicus Complex in these islands is significant from the viewpoint of vector control strategies.
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