Displaying publications 1 - 20 of 106 in total

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  1. 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.
    Matched MeSH terms: Malaria/diagnosis
  2. Ogunfowokan O, Ogunfowokan BA, Nwajei AI
    Afr J Prim Health Care Fam Med, 2020 Jun 17;12(1):e1-e8.
    PMID: 32634015 DOI: 10.4102/phcfm.v12i1.2212
    BACKGROUND: Malaria diagnosis using microscopy is currently the gold standard. However, malaria rapid diagnostic tests (mRDTs) were developed to simplify the diagnosis in regions without access to functional microscopy.

    AIM: The objective of this study was to compare the diagnostic accuracy of mRDT CareStatTM with microscopy.

    SETTING: This study was conducted in the paediatric primary care clinic of the Federal Medical Centre, Asaba, Nigeria.

    METHODS: A cross-sectional study for diagnostic accuracy was conducted from May 2016 to October 2016. Ninety-eight participants were involved to obtain a precision of 5%, sensitivity of mRDT CareStatTM of 95% from published work and 95% level of confidence after adjusting for 20% non-response rate or missing data. Consecutive participants were tested using both microscopy and mRDT. The results were analysed using EPI Info Version 7.

    RESULTS: A total of 98 children aged 3-59 months were enrolled. Malaria prevalence was found to be 53% (95% confidence interval [CI] = 46% - 60%), whilst sensitivity and specificity were 29% (95% CI = 20% - 38%) and 89% (95% CI = 83% - 95%), respectively. The positive and negative predictive values were 75% (95% CI = 66.4% - 83.6%) and 53% (95% CI = 46% - 60%), respectively.

    CONCLUSION: Agreement between malaria parasitaemia using microscopy and mRDT positivity increased with increase in the parasite density. The mRDT might be negative when malaria parasite density using microscopy is low.

    Matched MeSH terms: Malaria/diagnosis*
  3. Sidhu PS, Ng SC
    Ann Acad Med Singap, 1991 May;20(3):324-7.
    PMID: 1929172
    The case records of 64 patients with malaria over a five year period admitted to the University Hospital, Kuala Lumpur were examined. There were 32 cases of P. falciparum, 26 cases of P. vivax and two cases of mixed infections. Four cases of P. malariae were recorded. The clinical findings, biochemical and haematological parameters were examined for any indication of a pernicious syndrome. A high index of suspicion of a malarial infection may be based on the findings of anaemia, thrombocytopaenia, hyponatraemia, renal failure and abnormal liver function tests in the face of a negative blood film. These pernicious syndromes occur more often in malignant tertian malaria (anaemia 50%, hyponatraemia 39.1%) but a high percentage of the other malarial species show these abnormalities (P. vivax anaemia 57.7%, hyponatraemia 19.2%). When these abnormalities are present but blood films for malaria parasites are negative, repeat blood films are warranted until a parasitological diagnosis is achieved and correct treatment may be started.
    Matched MeSH terms: Malaria/diagnosis*
  4. Chen Y, Chan CK, Kerishnan JP, Lau YL, Wong YL, Gopinath SC
    BMC Infect Dis, 2015;15:49.
    PMID: 25656928 DOI: 10.1186/s12879-015-0786-2
    Plasmodium knowlesi was identified as the fifth major malaria parasite in humans. It presents severe clinical symptoms and leads to mortality as a result of hyperparasitemia in a short period of time. This study aimed to improve the current understanding of P. knowlesi and identify potential biomarkers for knowlesi malaria.
    Matched MeSH terms: Malaria/diagnosis*
  5. Fan L, Lee SY, Koay E, Harkensee C
    BMJ Case Rep, 2013;2013:bcr2013009558.
    PMID: 23608876 DOI: 10.1136/bcr-2013-009558
    Plasmodium knowlesi malaria is an uncommon, but highly prevalent parasitic infection in parts of Malaysia. This is the case of a 14-year-old Singaporean boy presenting to our emergency department with an 11-day history of fever following a school trip to Malaysia. Hepatosplenomegaly was the only clinical finding; laboratory tests showed thrombocytopaenia, lymphopaenia, mild anaemia and liver transaminitis. Specific malaria antigen tests were negative, but the peripheral blood film showed plasmodia with atypical features, with a parasite load of 0.5%. PCR confirmed the diagnosis of P knowlesi. The patient was successfully treated with chloroquine. The clinical course of P knowlesi malaria is indistinguishable from that of Plasmodium falciparum. This case highlights the importance of taking detailed travel history, careful examination of malaria blood films and judicious use of molecular techniques. Antigen tests alone may have missed a malaria diagnosis altogether, while blood film examination may wrongly identify the species as Plasmodium malariae or P falciparum. Third-generation PCR assays can be used to reliably identify P knowlesi.
    Matched MeSH terms: Malaria/diagnosis*
  6. Daneshvar C, Davis TM, Cox-Singh J, Rafa'ee MZ, Zakaria SK, Divis PC, et al.
    Clin Infect Dis, 2009 Sep 15;49(6):852-60.
    PMID: 19635025 DOI: 10.1086/605439
    BACKGROUND: Plasmodium knowlesi is increasingly recognized as a cause of human malaria in Southeast Asia but there are no detailed prospective clinical studies of naturally acquired infections.

    METHODS: In a systematic study of the presentation and course of patients with acute P. knowlesi infection, clinical and laboratory data were collected from previously untreated, nonpregnant adults admitted to the hospital with polymerase chain reaction-confirmed acute malaria at Kapit Hospital (Sarawak, Malaysia) from July 2006 through February 2008.

    RESULTS: Of 152 patients recruited, 107 (70%) had P. knowlesi infection, 24 (16%) had Plasmodium falciparum infection, and 21 (14%) had Plasmodium vivax. Patients with P. knowlesi infection presented with a nonspecific febrile illness, had a baseline median parasitemia value at hospital admission of 1387 parasites/microL (interquartile range, 6-222,570 parasites/microL), and all were thrombocytopenic at hospital admission or on the following day. Most (93.5%) of the patients with P. knowlesi infection had uncomplicated malaria that responded to chloroquine and primaquine treatment. Based on World Health Organization criteria for falciparum malaria, 7 patients with P. knowlesi infection (6.5%) had severe infections at hospital admission. The most frequent complication was respiratory distress, which was present at hospital admission in 4 patients and developed after admission in an additional 3 patients. P. knowlesi parasitemia at hospital admission was an independent determinant of respiratory distress, as were serum creatinine level, serum bilirubin, and platelet count at admission (p < .002 for each). Two patients with knowlesi malaria died, representing a case fatality rate of 1.8% (95% confidence interval, 0.2%-6.6%).

    CONCLUSIONS: Knowlesi malaria causes a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately 1 in 10 patients develop potentially fatal complications.

    Matched MeSH terms: Malaria/diagnosis*
  7. Singh B, Daneshvar C
    Clin Microbiol Rev, 2013 Apr;26(2):165-84.
    PMID: 23554413 DOI: 10.1128/CMR.00079-12
    Plasmodium knowlesi is a malaria parasite that is found in nature in long-tailed and pig-tailed macaques. Naturally acquired human infections were thought to be extremely rare until a large focus of human infections was reported in 2004 in Sarawak, Malaysian Borneo. Human infections have since been described throughout Southeast Asia, and P. knowlesi is now recognized as the fifth species of Plasmodium causing malaria in humans. The molecular, entomological, and epidemiological data indicate that human infections with P. knowlesi are not newly emergent and that knowlesi malaria is primarily a zoonosis. Human infections were undiagnosed until molecular detection methods that could distinguish P. knowlesi from the morphologically similar human malaria parasite P. malariae became available. P. knowlesi infections cause a spectrum of disease and are potentially fatal, but if detected early enough, infections in humans are readily treatable. In this review on knowlesi malaria, we describe the early studies on P. knowlesi and focus on the epidemiology, diagnosis, clinical aspects, and treatment of knowlesi malaria. We also discuss the gaps in our knowledge and the challenges that lie ahead in studying the epidemiology and pathogenesis of knowlesi malaria and in the prevention and control of this zoonotic infection.
    Matched MeSH terms: Malaria/diagnosis*
  8. Abdul-Nasir AS, Mashor MY, Mohamed Z
    Comput Math Methods Med, 2012;2012:637360.
    PMID: 23082089 DOI: 10.1155/2012/637360
    Malaria is one of the serious global health problem, causing widespread sufferings and deaths in various parts of the world. With the large number of cases diagnosed over the year, early detection and accurate diagnosis which facilitates prompt treatment is an essential requirement to control malaria. For centuries now, manual microscopic examination of blood slide remains the gold standard for malaria diagnosis. However, low contrast of the malaria and variable smears quality are some factors that may influence the accuracy of interpretation by microbiologists. In order to reduce this problem, this paper aims to investigate the performance of the proposed contrast enhancement techniques namely, modified global and modified linear contrast stretching as well as the conventional global and linear contrast stretching that have been applied on malaria images of P. vivax species. The results show that the proposed modified global and modified linear contrast stretching techniques have successfully increased the contrast of the parasites and the infected red blood cells compared to the conventional global and linear contrast stretching. Hence, the resultant images would become useful to microbiologists for identification of various stages and species of malaria.
    Matched MeSH terms: Malaria/diagnosis*
  9. Kantele A, Jokiranta S
    Duodecim, 2010;126(4):427-34.
    PMID: 20486493
    Four species have been known to bring on human malaria, the most severe disease being caused by Plasmodium falciparum. In 2007, after returning from Malaysia, a Finnish tourist was found to be infected with a fifth Plasmodium species, P. knowlesi which usually infects macaques. Over the past few years, hundreds of human cases have been found in Malaysia. The clinical disease caused by P. knowlesi appears less severe than P. falciparum infection, but more severe than infection with other malaria-causing species. Diagnosis is based both on PCR and microscopy. P. knowlesi is currently. considered as the fifth species causing malaria in humans.
    Matched MeSH terms: Malaria/diagnosis
  10. Barber BE, William T, Jikal M, Jilip J, Dhararaj P, Menon J, et al.
    Emerg Infect Dis, 2011 May;17(5):814-20.
    PMID: 21529389 DOI: 10.3201/eid1705.101489
    Plasmodium knowlesi can cause severe malaria in adults; however, descriptions of clinical disease in children are lacking. We reviewed case records of children (age <15 years) with a malaria diagnosis at Kudat District Hospital, serving a largely deforested area of Sabah, Malaysia, during January-November 2009. Sixteen children with PCR-confirmed P. knowlesi monoinfection were compared with 14 children with P. falciparum monoinfection diagnosed by microscopy or PCR. Four children with knowlesi malaria had a hemoglobin level at admission of <10.0 g/dL (minimum lowest level 6.4 g/dL). Minimum level platelet counts were lower in knowlesi than in falciparum malaria (median 76,500/μL vs. 156,000/mL; p = 0.01). Most (81%) children with P. knowlesi malaria received chloroquine and primaquine; median parasite clearance time was 2 days (range 1-5 days). P. knowlesi is the most common cause of childhood malaria in Kudat. Although infection is generally uncomplicated, anemia is common and thrombocytopenia universal. Transmission dynamics in this region require additional investigation.
    Matched MeSH terms: Malaria/diagnosis
  11. Lau YL, Tan LH, Chin LC, Fong MY, Noraishah MA, Rohela M
    Emerg Infect Dis, 2011 Jul;17(7):1314-5.
    PMID: 21762601 DOI: 10.3201/eid1707.101295
    Matched MeSH terms: Malaria/diagnosis*
  12. Hartmeyer GN, Stensvold CR, Fabricius T, Marmolin ES, Hoegh SV, Nielsen HV, et al.
    Emerg Infect Dis, 2019 10;25(10):1936-1939.
    PMID: 31538931 DOI: 10.3201/eid2510.190448
    We report human infection with simian Plasmodium cynomolgi in a tourist from Denmark who had visited forested areas in peninsular Malaysia and Thailand in August and September 2018. Because P. cynomolgi may go unnoticed by standard malaria diagnostics, this malaria species may be more common in humans than was previously thought.
    Matched MeSH terms: Malaria/diagnosis
  13. Sonaimuthu P, Cheong FW, Chin LC, Mahmud R, Fong MY, Lau YL
    Exp Parasitol, 2015 Jun;153:118-22.
    PMID: 25812552 DOI: 10.1016/j.exppara.2015.03.010
    Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Human infection with Plasmodium knowlesi is widely distributed in Southeast Asia. Merozoite surface protein-1₁₉ (MSP-1₁₉), which plays an important role in protective immunity against asexual blood stage malaria parasites, appears as a leading immunogenic antigen of Plasmodium sp. We evaluated the sensitivity and specificity of recombinant P. knowlesi MSP-1₁₉ (rMSP-1₁₉) for detection of malarial infection. rMSP-1₁₉ was expressed in Escherichia coli expression system and the purified rMSP-1₁₉ was evaluated with malaria, non-malaria and healthy human serum samples (n = 215) in immunoblots. The sensitivity of rMSP-1₁₉ for detection of P. knowlesi, Plasmodium falciparum, Plasmodium  vivax and Plasmodium  ovale infection was 95.5%, 75.0%, 85.7% and 100%, respectively. rMSP-1₁₉ did not react with all the non-malaria and healthy donor sera, which represents 100% specificity. The rMSP-1₁₉ could be used as a potential antigen in serodiagnosis of malarial infection in humans.
    Matched MeSH terms: Malaria/diagnosis
  14. Kojom Foko LP, Kouemo Motse FD, Kamgain Mawabo L, Pande V, Singh V
    Infect Genet Evol, 2021 07;91:104797.
    PMID: 33676011 DOI: 10.1016/j.meegid.2021.104797
    The performances of a commonly used Plasmodium falciparum-detecting rapid diagnostic test (RDT) were determined in symptomatic individuals living in Cameroon. Discrepancies between RDT and light microscopy (LM) results were further investigated, with a focus on non-falciparum malaria (NFM) which are still largely understudied in sub-Saharan Africa (sSA) countries. In the present study, a total of 355 individuals aged 1-65 years were enrolled in the study. Their signs/symptoms and sociodemographic characteristics were documented. The RDT reliability was evaluated using LM as gold standard method. Polymerase chain reaction (PCR) of Plasmodium 18S gene was performed for samples with discordant results between LM and RDT (i.e., RDT-/LM+, and RDT+/LM-). The PCR amplicons of NFM species were sequenced and BLASTed. The prevalence of malaria infection by LM was 95.7% (95% CI: 93.1-97.4%). The sensitivity and specificity of RDT for P. falciparum detection was 94.0% and 66.7%, respectively. By PCR assay, P. ovale curtisi (PoC) was found in 5 of the 30 discordant samples, and on sequence analysis these isolates were found to be phylogenetically closer to sequences reported from China-Myanmar border and Malaysia. This is the first report on molecular characterization of P. ovale subspecies in Cameroon. The study also outlines the good diagnostic performances of the RDT for detection of P. falciparum. Though, the presence of PoC indicated the importance of having RDTs targeting the NFM species in malaria diagnosis and treatment, which is presently limited in the country.
    Matched MeSH terms: Malaria/diagnosis*
  15. Singh B
    Int J Parasitol, 1997 Oct;27(10):1135-45.
    PMID: 9394184
    Direct microscopy is widely used for the diagnosis of parasitic infections although it often requires an experienced microscopist for accurate diagnosis, is labour intensive and not very sensitive. In order to overcome some of these shortcomings, molecular or nucleic acid-based diagnostic methods for parasitic infections have been developed over the past 12 years. The parasites which have been studied with these techniques include the human Plasmodia, Leishmania, the trypanosomes, Toxoplasma gondii, Entamoeba histolytica, Giardia, Trichomonas vaginalis, Cryptosporidium parvum, Taenia, Echinococcus, Brugia malayi, Wuchereria bancrofti, Loa loa and Onchocerca volvulus. Early methods, which involved hybridisation of specific probes (radiolabelled and non-radiolabelled) to target deoxyribonucleic acid (DNA), have been replaced by more sensitive polymerase chain reaction (PCR)-based assays. Other methods, such as PCR-hybridisation assays, PCR-restriction fragment length polymorphism (PCR-RFLP) assays and random amplified polymorphic DNA (RAPD) analysis have also proved valuable for epidemiological studies of parasites. The general principles and development of DNA-based methods for diagnosis and epidemiological studies will be described, with particular reference to malaria. These methods will probably not replace current methods for routine diagnosis of parasitic infections in developing countries where parasitic diseases are endemic, due to high costs. However, they will be extremely useful for genotyping parasite strains and vectors, and for accurate parasite detection in both humans and vectors during epidemiological studies.
    Matched MeSH terms: Malaria/diagnosis
  16. Lee KS, Cox-Singh J, Brooke G, Matusop A, Singh B
    Int J Parasitol, 2009 Aug;39(10):1125-8.
    PMID: 19358848 DOI: 10.1016/j.ijpara.2009.03.003
    Human infections with Plasmodium knowlesi have been misdiagnosed by microscopy as Plasmodium malariae due to their morphological similarities. Although microscopy-identified P. malariae cases have been reported in the state of Sarawak (Malaysian Borneo) as early as 1952, recent epidemiological studies suggest the absence of indigenous P. malariae infections. The present study aimed to determine the past incidence and distribution of P. knowlesi infections in the state of Sarawak based on archival blood films from patients diagnosed by microscopy as having P. malariae infections. Nested PCR assays were used to identify Plasmodium species in DNA extracted from 47 thick blood films collected in 1996 from patients in seven different divisions throughout the state of Sarawak. Plasmodium knowlesi DNA was detected in 35 (97.2%) of 36 blood films that were positive for Plasmodium DNA, with patients originating from all seven divisions. Only one sample was positive for P. malariae DNA. This study provides further evidence of the widespread distribution of human infections with P. knowlesi in Sarawak and its past occurrence. Taken together with data from previous studies, our findings suggest that P. knowlesi malaria is not a newly emergent disease in humans.
    Matched MeSH terms: Malaria/diagnosis*
  17. Cho SJ, Lee J, Lee HJ, Jo HY, Sinniah M, Kim HY, et al.
    Int J Biol Sci, 2016;12(7):824-35.
    PMID: 27313496 DOI: 10.7150/ijbs.14408
    Rapid diagnostic tests (RDTs) can detect anti-malaria antibodies in human blood. As they can detect parasite infection at the low parasite density, they are useful in endemic areas where light infection and/or re-infection of parasites are common. Thus, malaria antibody tests can be used for screening bloods in blood banks to prevent transfusion-transmitted malaria (TTM), an emerging problem in malaria endemic areas. However, only a few malaria antibody tests are available in the microwell-based assay format and these are not suitable for field application. A novel malaria antibody (Ab)-based RDT using a differential diagnostic marker for falciparum and vivax malaria was developed as a suitable high-throughput assay that is sensitive and practical for blood screening. The marker, merozoite surface protein 1 (MSP1) was discovered by generation of a Plasmodium-specific network and the hierarchical organization of modularity in the network. Clinical evaluation revealed that the novel Malaria Pf/Pv Ab RDT shows improved sensitivity (98%) and specificity (99.7%) compared with the performance of a commercial kit, SD BioLine Malaria P.f/P.v (95.1% sensitivity and 99.1% specificity). The novel Malaria Pf/Pv Ab RDT has potential for use as a cost-effective blood-screening tool for malaria and in turn, reduces TTM risk in endemic areas.
    Matched MeSH terms: Malaria/diagnosis*
  18. Oluchi SE, Manaf RA, Ismail S, Udeani TK
    PMID: 31590340 DOI: 10.3390/ijerph16193752
    Fever is one of the most common symptoms of pediatric illnesses; it is an important early symptom of malaria. Fever had served as the entry point for presumptive treatment of malaria among children in Nigerian. Appropriate HSB is important when seeking treatment for fever among under-five children; this will help for better prognosis because treatment will be initiated early. This study attempted to identify caregiver's HSB for under-five children with fever. A cross-sectional study was conducted in Imo-State, Nigeria. Appropriate HSB was operationally defined as seeking treatment from health facility within 24 h of fever. Data were obtained using pretested self-administered questionnaire. Data were analyzed using SPSS version 22. Simple and multiple logistic regression were used to determine predictors of appropriate HSB. A total of 559 eligible respondents were recruited; 103 (18.6%) caregivers had appropriate HSB. The predictors of HSB are being male child (aOR = 2.760; 95% CI:1.536-4.958), the age of child younger than 27 months (aOR = 2.804; 95% CI:1.485-5.295), employed caregivers (aOR = 1.882; 95% CI:1.014-3.493), number of household members (aOR = 2.504; 95% CI:1.464-4.283), and caregivers who decided to seek treatment at early stage (aOR = 7.060; 95% CI:1.616-30.852). Only 18.6% caregivers practiced appropriate HSB for fever cases among under-five children. It is essential to educate caregivers and emphasise on early treatment of fever and appropriate use of health facilities for fever. The findings will be used to improve intervention at the community level and will be compared with follow-up data to evaluate their effectiveness.
    Matched MeSH terms: Malaria/diagnosis*
  19. Müller M, Schlagenhauf P
    Int J Infect Dis, 2014 May;22:55-64.
    PMID: 24631521 DOI: 10.1016/j.ijid.2013.12.016
    Since the initial discovery of Plasmodium knowlesi in Malaysia, cases have been reported from several neighbouring countries. Tourism has also resulted in an increasing number of cases diagnosed in Europe, America, and Oceania. In this review we focus on the risk of the travel-associated acquisition of P. knowlesi malaria.
    Matched MeSH terms: Malaria/diagnosis*
  20. Mu AK, Bee PC, Lau YL, Chen Y
    Int J Mol Sci, 2014;15(11):19952-61.
    PMID: 25372941 DOI: 10.3390/ijms151119952
    Malaria is caused by parasitic protozoans of the genus Plasmodium and is one of the most prevalent infectious diseases in tropical and subtropical regions. For this reason, effective and practical diagnostic methods are urgently needed to control the spread of malaria. The aim of the current study was to identify a panel of new malarial markers, which could be used to diagnose patients infected with various Plasmodium species, including P. knowlesi, P. vivax and P. falciparum. Sera from malaria-infected patients were pooled and compared to control sera obtained from healthy individuals using the isobaric tags for relative and absolute quantitation (iTRAQ) technique. Mass spectrometry was used to identify serum proteins and quantify their relative abundance. We found that the levels of several proteins were increased in pooled serum from infected patients, including cell adhesion molecule-4 and C-reactive protein. In contrast, the serum concentration of haptoglobin was reduced in malaria-infected individuals, which we verified by western blot assay. Therefore, these proteins might represent infectious markers of malaria, which could be used to develop novel diagnostic tools for detecting P. knowlesi, P. vivax and P. falciparum. However, these potential malarial markers will need to be validated in a larger population of infected individuals.
    Matched MeSH terms: Malaria/diagnosis*
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