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Evaluation of filter paper eluates for seroepidemiological studies on malaria in peninsular Malaysia

Thomas V, Chan WC

Trop Geogr Med, 1982 Jun;34(2):145-9.
PMID: 6750883
Matched MeSH terms: Malaria/parasitology
Fulltext Studies on the biology of Anopheles letifer Sandosham (Diptera, Culicidae) and its response to residual spraying, carried out in Sarawak, Malaysia

Thevasagayam ES, Liaw CF

Med J Malaysia, 1980 Mar;34(3):254-64.
PMID: 7191047
Matched MeSH terms: Malaria/parasitology
Development of an optical biosensor for the detection of Trypanosoma evansi and Plasmodium berghei

Theint HT, Walsh JE, Wong ST, Voon K, Shitan M

Spectrochim Acta A Mol Biomol Spectrosc, 2019 Jul 05;218:348-358.
PMID: 31026712 DOI: 10.1016/j.saa.2019.04.008

A laboratory prototype system that correlates murine blood absorbance with degree of infection for Plasmodium berghei and Trypanosoma avensi has been designed, constructed and tested. A population (n = 6) of control uninfected, Plasmodium infected and Trypanosoma infected BALB/c mice were developed and spectral absorption measurements pre and post infection were made every 3 days. A fibre optic spectrometer set-up was used as the basis of a laboratory prototype biosensor that uses the Beer Lambert Law to relate Ultraviolet-Visible-Near-infrared absorbance data to changes in murine blood chemistry post infection. Spectral absorption results indicate a statistically relevant correlation at a 650 nm with infection for Plasmodium from between 4 and 7 sampling days' post infection, in spite of significant standard deviations among the sample populations for control and infected mice. No significant spectral absorption change for Trypanosoma infection was been detected from the current data. Corresponding stained slides of control and infected blood at each sampling date were taken with related infected cell counts determined and these correlate well for Plasmodium absorbance at 650 nm.

Matched MeSH terms: Malaria/parasitology
Fulltext First case of Plasmodium knowlesi infection in a Japanese traveller returning from Malaysia

Tanizaki R, Ujiie M, Kato Y, Iwagami M, Hashimoto A, Kutsuna S, et al.

Malar J, 2013;12:128.
PMID: 23587117 DOI: 10.1186/1475-2875-12-128

This is the first case of Plasmodium knowlesi infection in a Japanese traveller returning from Malaysia. In September 2012, a previously healthy 35-year-old Japanese man presented to National Center for Global Health and Medicine in Tokyo with a two-day history of daily fever, mild headaches and mild arthralgia. Malaria parasites were found in the Giemsa-stained thin blood smear, which showed band forms similar to Plasmodium malariae. Although a nested PCR showed the amplification of the primer of Plasmodium vivax and Plasmodium knowlesi, he was finally diagnosed with P. knowlesi mono-infection by DNA sequencing. He was treated with mefloquine, and recovered without any complications. DNA sequencing of the PCR products is indispensable to confirm P. knowlesi infection, however there is limited access to DNA sequencing procedures in endemic areas. The extent of P. knowlesi transmission in Asia has not been clearly defined. There is limited availability of diagnostic tests and routine surveillance system for reporting an accurate diagnosis in the Asian endemic regions. Thus, reporting accurately diagnosed cases of P. knowlesi infection in travellers would be important for assessing the true nature of this emerging human infection.

Matched MeSH terms: Malaria/parasitology
Fulltext Bionomics of Anopheles latens in Kapit, Sarawak, Malaysian Borneo in relation to the transmission of zoonotic simian malaria parasite Plasmodium knowlesi

Tan CH, Vythilingam I, Matusop A, Chan ST, Singh B

Malar J, 2008;7:52.
PMID: 18377652 DOI: 10.1186/1475-2875-7-52

A large focus of human infections with Plasmodium knowlesi, a simian parasite naturally found in long-tailed and pig-tailed macaques was discovered in the Kapit Division of Sarawak, Malaysian Borneo. A study was initiated to identify the vectors of malaria, to elucidate where transmission is taking place and to understand the bionomics of the vectors in Kapit.

Matched MeSH terms: Malaria/parasitology*
Fulltext First case of detection of Plasmodium knowlesi in Spain by Real Time PCR in a traveller from Southeast Asia

Ta TT, Salas A, Ali-Tammam M, Martínez Mdel C, Lanza M, Arroyo E, et al.

Malar J, 2010;9:219.
PMID: 20663184 DOI: 10.1186/1475-2875-9-219

Previously, Plasmodium knowlesi was not considered as a species of Plasmodium that could cause malaria in human beings, as it is parasite of long-tailed (Macaca fascicularis) and pig-tailed (Macaca nemestrina) macaques found in Southeast Asia. A case of infection by P. knowlesi is described in a Spanish traveller, who came back to Spain with daily fever after his last overseas travel, which was a six-month holiday in forested areas of Southeast Asia between 2008 and 2009. His P. knowlesi infection was detected by multiplex Real time quantitative PCR and confirmed by sequencing the amplified fragment. Using nested multiplex malaria PCR (reference method in Spain) and a rapid diagnostic test, the P. knowlesi infection was negative. This patient was discharged and asymptomatic when the positive result to P. knowlesi was reported. Prior to this case, there have been two more reports of European travellers with malaria caused by P. knowlesi, a Finnish man who travelled to Peninsular Malaysia during four weeks in March 2007, and a Swedish man who did a short visit to Malaysian Borneo in October 2006. Taken together with this report of P. knowlesi infection in a Spanish traveller returning from Southeast Asia, this is the third case of P. knowlesi infection in Europe, indicating that this simian parasite can infect visitors to endemic areas in Southeast Asia. This last European case is quite surprising, given that it is an untreated-symptomatic P. knowlesi in human, in contrast to what is currently known about P. knowlesi infection. Most previous reports of human P. knowlesi malaria infections were in adults, often with symptoms and relatively high parasite densities, up to the recent report in Ninh Thuan province, located in the southern part of central Vietnam, inhabited mainly by the Ra-glai ethnic minority, in which all P. knowlesi infections were asymptomatic, co-infected with P. malariae, with low parasite densities and two of the three identified cases were very young children under five years old.

Matched MeSH terms: Malaria/parasitology*
Fulltext First case of a naturally acquired human infection with Plasmodium cynomolgi

Ta TH, Hisam S, Lanza M, Jiram AI, Ismail N, Rubio JM

Malar J, 2014;13:68.
PMID: 24564912 DOI: 10.1186/1475-2875-13-68

Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans.The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods.Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax.This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax.Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its implication on human public health and in the control of human malaria.The zoonotic malaria cannot be ignored in view of increasing interactions between man and wild animals in the process of urbanization.

Matched MeSH terms: Malaria/parasitology*
Malaria, anti malarial drugs and the role of melatonin

Srinivasan V, Mohamed M, Zakaria R, Ahmad AH

Infect Disord Drug Targets, 2012 Oct;12(5):371-9.
PMID: 23082960

Malaria, one of the most deadly diseases of our time affects more than 200 million people across the globe and is responsible for about one million deaths annually. Until recently Plasmodium falciparum has been the main cause for malarial infection in human beings but now Plasmodium knowlesi from Malaysia remains as one of the most virulent parasite spreading fast not only in Malaysia but in different parts of the world. Hence there is urgent need for the global fight to control malaria. Global malaria eradication program by use of insecticide spraying has resulted in good response in the past. Treatment of malaria infected patients with anti-malarial drugs has helped to eliminate malarial infections successfully but with increased resistance displayed by malarial parasites to these drugs there is resurgence of malaria caused both by drug resistance as well as by infection caused by new malarial species like Plasmodium knowlesi. With recent advances on molecular studies on malarial parasites it is now clear that the pineal hormone melatonin acts as a cue for growth and development of Plasmodium falciparum. Same may be true for Plasmodium knowlesi also. Hence treatment modalities that can effectively block the action of melatonin on Plasmodium species during night time by way of using either bright light therapy or use of melatonin receptor blocking can be considered as useful approaches for eliminating malarial infection in man.

Matched MeSH terms: Malaria/parasitology
Detection of human malaria using recombinant Plasmodium knowlesi merozoire surface protein-1 (MSP-1₁₉) expressed in Escherichia coli

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/parasitology
Detection of malaria in Malaysia by nested polymerase chain reaction amplification of dried blood spots on filter papers

Singh B, Cox-Singh J, Miller AO, Abdullah MS, Snounou G, Rahman HA

Trans R Soc Trop Med Hyg, 1996 9 1;90(5):519-21.
PMID: 8944260

A modified nested polymerase chain reaction (PCR) method for detection of Plasmodium falciparum, P. vivax and P. malariae was combined with a simple blood collection and deoxyribonucleic acid (DNA) extraction method and evaluated in Malaysia. Finger-prick blood samples from 46 hospital patients and 120 individuals living in malaria endemic areas were spotted on filter papers and dried. The simple Chelex method was used to prepare DNA templates for the nested PCR assay. Higher malaria prevalence rates for both clinical (78.2%) and field samples (30.8%) were obtained with the nested PCR method than by microscopy (76.1% and 27.5%, respectively). Nested PCR was more sensitive than microscopy in detecting mixed P. falciparum and P. vivax infections, detected 5 more malaria samples than microscopy on the first round of microscopical examination, and detected malaria in 3 microscopically negative samples. Nested PCR failed to detect parasite DNA in 2 microscopically positive samples, an overall sensitivity of 97.4% compared to microscopy. The nested PCR method, when coupled with simple dried blood spot sampling, is a useful tool for collecting accurate malaria epidemiological data, particularly in remote regions of the world.

Matched MeSH terms: Malaria/parasitology
A large focus of naturally acquired Plasmodium knowlesi infections in human beings

Singh B, Kim Sung L, Matusop A, Radhakrishnan A, Shamsul SS, Cox-Singh J, et al.

Lancet, 2004 Mar 27;363(9414):1017-24.
PMID: 15051281

About a fifth of malaria cases in 1999 for the Kapit division of Malaysian Borneo had routinely been identified by microscopy as Plasmodium malariae, although these infections appeared atypical and a nested PCR assay failed to identify P malariae DNA. We aimed to investigate whether such infections could be attributable to a variant form of P malariae or a newly emergent Plasmodium species.

Matched MeSH terms: Malaria/parasitology*
Fulltext Orangutans not infected with Plasmodium vivax or P. cynomolgi, Indonesia

Singh B, Simon Divis PC

Emerg Infect Dis, 2009 Oct;15(10):1657-8.
PMID: 19861067 DOI: 10.3201/eid1510.090364

After orangutans in Indonesia were reported as infected with Plasmodium cynomolgi and P. vivax, we conducted phylogenetic analyses of small subunit ribosomal RNA gene sequences of Plasmodium spp. We found that these orangutans are not hosts of P. cynomolgi and P. vivax. Analysis of >or=1 genes is needed to identify Plasmodium spp. infecting orangutans.

Matched MeSH terms: Malaria/parasitology
Fulltext Absence of Plasmodium inui and Plasmodium cynomolgi, but detection of Plasmodium knowlesi and Plasmodium vivax infections in asymptomatic humans in the Betong division of Sarawak, Malaysian Borneo

Siner A, Liew ST, Kadir KA, Mohamad DSA, Thomas FK, Zulkarnaen M, et al.

Malar J, 2017 Oct 17;16(1):417.
PMID: 29041929 DOI: 10.1186/s12936-017-2064-9

BACKGROUND: Plasmodium knowlesi, a simian malaria parasite, has become the main cause of malaria in Sarawak, Malaysian Borneo. Epidemiological data on malaria for Sarawak has been derived solely from hospitalized patients, and more accurate epidemiological data on malaria is necessary. Therefore, a longitudinal study of communities affected by knowlesi malaria was undertaken.
METHODS: A total of 3002 blood samples on filter paper were collected from 555 inhabitants of 8 longhouses with recently reported knowlesi malaria cases in the Betong Division of Sarawak, Malaysian Borneo. Each longhouse was visited bimonthly for a total of 10 times during a 21-month study period (Jan 2014-Oct 2015). DNA extracted from blood spots were examined by a nested PCR assay for Plasmodium and positive samples were then examined by nested PCR assays for Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, Plasmodium knowlesi, Plasmodium cynomolgi and Plasmodium inui. Blood films of samples positive by PCR were also examined by microscopy.
RESULTS: Genus-specific PCR assay detected Plasmodium DNA in 9 out of 3002 samples. Species-specific PCR identified 7 P. knowlesi and one P. vivax. Malaria parasites were observed in 5 thick blood films of the PCR positive samples. No parasites were observed in blood films from one knowlesi-, one vivax- and the genus-positive samples. Only one of 7 P. knowlesi-infected individual was febrile and had sought medical treatment at Betong Hospital the day after sampling. The 6 knowlesi-, one vivax- and one Plasmodium-infected individuals were afebrile and did not seek any medical treatment.
CONCLUSIONS: Asymptomatic human P. knowlesi and P. vivax malaria infections, but not P. cynomolgi and P. inui infections, are occurring within communities affected with malaria.

Matched MeSH terms: Malaria/parasitology
Fulltext Estimating Geographical Variation in the Risk of Zoonotic Plasmodium knowlesi Infection in Countries Eliminating Malaria

Shearer FM, Huang Z, Weiss DJ, Wiebe A, Gibson HS, Battle KE, et al.

PLoS Negl Trop Dis, 2016 Aug;10(8):e0004915.
PMID: 27494405 DOI: 10.1371/journal.pntd.0004915

BACKGROUND: Infection by the simian malaria parasite, Plasmodium knowlesi, can lead to severe and fatal disease in humans, and is the most common cause of malaria in parts of Malaysia. Despite being a serious public health concern, the geographical distribution of P. knowlesi malaria risk is poorly understood because the parasite is often misidentified as one of the human malarias. Human cases have been confirmed in at least nine Southeast Asian countries, many of which are making progress towards eliminating the human malarias. Understanding the geographical distribution of P. knowlesi is important for identifying areas where malaria transmission will continue after the human malarias have been eliminated.
METHODOLOGY/PRINCIPAL FINDINGS: A total of 439 records of P. knowlesi infections in humans, macaque reservoir and vector species were collated. To predict spatial variation in disease risk, a model was fitted using records from countries where the infection data coverage is high. Predictions were then made throughout Southeast Asia, including regions where infection data are sparse. The resulting map predicts areas of high risk for P. knowlesi infection in a number of countries that are forecast to be malaria-free by 2025 (Malaysia, Cambodia, Thailand and Vietnam) as well as countries projected to be eliminating malaria (Myanmar, Laos, Indonesia and the Philippines).
CONCLUSIONS/SIGNIFICANCE: We have produced the first map of P. knowlesi malaria risk, at a fine-scale resolution, to identify priority areas for surveillance based on regions with sparse data and high estimated risk. Our map provides an initial evidence base to better understand the spatial distribution of this disease and its potential wider contribution to malaria incidence. Considering malaria elimination goals, areas for prioritised surveillance are identified.

Matched MeSH terms: Malaria/parasitology
Fulltext Characterization of malaria infection at two border areas of Thailand adjoining with Myanmar and Malaysia

Sermwittayawong N, Nishibuchi M, Sawangjaroen N, Vuddhakul V

Southeast Asian J. Trop. Med. Public Health, 2015 Jul;46(4):551-7.
PMID: 26867373

During 2009 to 2010, a total of 408 blood samples collected from malaria patients in Ranong (149) and Yala (259) Provinces, Thailand were investigated for Plasmodium spp using microscopic examination. There are no statistical differences in the prevalence of P. falciparum and P. vivax in samples collected from Ranong and Yala (46% vs 52%, and 54% vs 45%, respectively). Single nucleotide polymorphism of codon 86 in pfmdr1 (encoding P. falciparum multidrug resistance protein 1) was investigated among 75 samples of P. falciparum and 2 samples of P. knowlesi. A pfmdr1 N86Y mutation was detected in 1 out of 29 samples and 45 out of 46 samples obtained from Ranong and Yala Provinces, respectively. It is interesting that pfmdr1 was detected in two P. knowlesi DNA samples obtained previously from Ranong Province which was 99% homologous to pfmdr1 obtained from falciparum parasites in the same area but the mutation was not observed. The difference in multidrug resistance protein in Plasmodium obtained from those two border areas of Thailand will be of use in monitoring drug resistance in these border regions of the country.

Matched MeSH terms: Malaria/parasitology
Plasmodium knowlesi: from Malaysia, a novel health care threat

Sabbatani S, Fiorino S, Manfredi R

Infez Med, 2012 Mar;20(1):5-11.
PMID: 22475654

Epidemic foci of Plasmodium knowlesi malaria have been identified during the past ten years in Malaysia, in particular in the States of Sarawak and Sabah (Malaysia Borneo), and in the Pahang region (peninsular Malaysia). Based on a review of the available recent international literature, the authors underline the importance of molecular biology examinations, polymerase chain reactions (PCR), performed with primers specific for P. knowlesi, since the current microscopic examination (haemoscope) may fail to distinguish P. knowlesi from Plasmodium malariae, due to the very similar appearance of the two parasites. P. knowlesi has been described as the causal agent of life-threatening and lethal forms of malaria: its clinical picture is more severe when compared with that of P. malariae, since the disease is characterized by greater parasitaemia, as opposed to that documented in the course of P. malariae disease. The most effective carrier is Anopheles leucosphyrus: this mosquito is attracted by both humans and monkeys. Among primates, the natural hosts of P. knowlesi are Macaca fascicularis and Macaca nemestina, while Saimiri scirea and Macaca mulatta, which cannot become infected in nature, may be useful in experimental models. When underlining the potentially severe evolution, we note the key role played by prompt disease recognition, which is expected to be more straightforward in patients monitored in endemic countries at high risk, but should be carefully implemented for subjects being admitted to hospital in Western countries suffering from the typical signs and symptoms of malaria, after travelling in South-East Asia where they were engaged in excursions in the tropical forest (trekking, and similar outdoor activities). In these cases, the diagnosis should be prompt, and suitable treatment should follow. According to data in the literature, in non-severe cases chloroquine proves very effective against P. knowlesi, achieving the disappearance of signs and symptoms in 96% of cases after only 24 hours after treatment start. In the light of the emerging epidemiological data, P. knowlesi should be added to Plasmodium vivax, Plasmodium ovale, P. malariae, and Plasmodium falciparum, as the fifth aetiological agent of malaria. During the next few years, it will become mandatory to plan an appropriate surveillance program of the epidemiological evolution, paying also great attention to the clinical features of patients affected by P. knowlesi malaria, which are expected to worsen according to the time elapsed; some studies seem to point out greater severity according to increased parasitaemia, paralleling the increased interhuman infectious passages of the plasmodium.

Matched MeSH terms: Malaria/parasitology*
Fulltext The emerging of the fifth malaria parasite (Plasmodium knowlesi): a public health concern?

Sabbatani S, Fiorino S, Manfredi R

Braz J Infect Dis, 2010 May-Jun;14(3):299-309.
PMID: 20835518

After examining the most recent scientific evidences, which assessed the role of some malaria plasmodia that have monkeys as natural reservoirs, the authors focus their attention on Plasmodium knowlesi. The infective foci attributable to this last Plasmodium species have been identified during the last decade in Malaysia, in particular in the states of Sarawak and Sabah (Malaysian Borneo), and in the Pahang region (peninsular Malaysia). The significant relevance of molecular biology assays (polymerase chain reaction, or PCR, performed with specific primers for P. knowlesi), is underlined, since the traditional microscopic examination does not offer distinguishing features, especially when the differential diagnosis with Plasmodium malariae is of concern. Furthermore, Plasmodium knowlesi disease may be responsible of fatal cases, since its clinical presentation and course is more severe compared with those caused by P. malariae, paralleling a more elevated parasitemia. The most effective mosquito vector is represented by Anopheles latens; this mosquito is a parasite of both humans and monkeys. Among primates, the natural hosts are Macaca fascicularis, M. nemestina, M. inus, and Saimiri scirea. When remarking the possible severe evolution of P. knowlesi malaria, we underline the importance of an early recognition and a timely management, especially in patients who have their first onset in Western Hospitals, after journeys in Southeast Asian countries, and eventually participated in trekking excursions in the tropical forest. When malaria-like signs and symptoms are present, a timely diagnosis and treatment become crucial. In the light of its emerging epidemiological features, P. knowlesi may be added to the reknown human malaria parasites, whith includes P. vivax, P. ovale, P. malariae, and P. falciparum, as the fifth potential ethiologic agent of human malaria. Over the next few years, it will be mandatory to support an adequate surveillance and epidemiological network. In parallel with epidemiological and health care policy studies, also an accurate appraisal of the clinical features of P. knowlesi-affected patients will be strongly needed, since some preliminary experiences seem to show an increased disease severity, associated with increased parasitemia, in parallel with the progressive increase of inter-human infectious passages of this emerging Plasmodium.

Matched MeSH terms: Malaria/parasitology*
Demographic, clinical and laboratory features of leptospirosis-malaria co-infections in Peninsular Malaysia

Rao M, Atiqah N, Dasiman M, Amran F

J Med Microbiol, 2020 Mar;69(3):451-456.
PMID: 31846413 DOI: 10.1099/jmm.0.001127

Introduction. Co-infection of leptospirosis-malaria is not uncommon due to their overlapping geographical distribution in the tropics.Aim. This study aimed to describe and compare the demographic, clinical and laboratory features of leptospirosis-malaria co-infection (LMCI) against leptospirosis mono-infection (LMI) in Peninsular Malaysia.Methodology. Data of patients admitted to various hospitals in Peninsular Malaysia from 2011 to 2014 diagnosed with leptospirosis in our laboratory were obtained from their admission records. Co-infections with malaria were identified via blood film for malaria parasites (BFMP). Description with inferential statistics analysis and multiple logistic regressions were used to distinguish features between dual and mono-infections.Results. Of 111 leptospirosis-positive patients, 26 (23.4 %) tested positive for malaria. Co-infections were predominant among male patients with a mean age of 33 years and were prevalent among immigrant populations who had settled in high-density suburban areas. Chills and rigor with splenomegaly were the only significant distinguishing clinical features of LMCI while leukocytosis and raised transaminases were significant laboratory parameters. Only chills and rigor demonstrated a predictive value for LMCI from analysis of multiple logistic regressions. No death was attributed to co-infection in this study, in contrast to LMI (11.8 %, n=10).Conclusion. The significant prevalence of LMCI found in this study with overlapping demographic, clinical and laboratory parameters makes diagnosis of co-infection challenging. It is essential to evaluate co-infection in endemic areas. Strengthened awareness of LMCI, comprehensive diagnostic services and further prospective studies are warranted.

Matched MeSH terms: Malaria/parasitology
Assessment of Commercial Real-Time PCR Assays for Detection of Malaria Infection in a Non-Endemic Setting

Ramírez AM, Tang THT, Suárez ML, Fernández AÁ, García CM, Hisam S, et al.

Am J Trop Med Hyg, 2021 Oct 12;105(6):1732-1737.
PMID: 34662870 DOI: 10.4269/ajtmh.21-0406

Malaria control and elimination require prompt diagnosis and accurate treatment. Conventional methods such as rapid diagnostic tests (RDTs) and microscopy lack the characteristics to detect low parasitemias, commonly found in asymptomatic parasitemias and/or submicroscopic malaria carriers. On the contrary, molecular methods have higher sensitivity and specificity. This study evaluated the performance of two commercial real-time polymerase chain reaction (PCR) assays, RealStar® Malaria PCR (RealStar-genus) and RealStar Malaria Screen&Type PCR (RealStar-species), compared with the reference Nested Multiplex Malaria PCR, for the detection of the main five Plasmodium species affecting humans. A total of 121 samples were evaluated. Values of sensitivity (98.9% and 97.8%) and specificity (100% and 96.7%) of the RealStar-genus and the RealStar-species assays, respectively, were very good. The limit of detection (LoD) for the RealStar-genus assay showed a mean value of 0.28 parasites/µL with Plasmodium falciparum samples; while, the LoD of the RealStar-species assay ranged from 0.09 parasites/µL for P. vivax to two parasites/µL for P. ovale. The time to complete a diagnosis was established in 4 hours. Our findings showed a very good concordance of both assays compared with the reference method, with a very good analytical sensitivity. RealStar-species assay was able to correctly characterize double and triple infections. Therefore, these RealStar assays have shown to be useful tools in malaria diagnosis in non-endemic countries and even endemic countries, and for malaria control in general, detecting low parasitemias with sensitivity similar to the most sensitive methods as nested PCR, but with lower time to get the results.

Matched MeSH terms: Malaria/parasitology
Fulltext Deaths due to Plasmodium knowlesi malaria in Sabah, Malaysia: association with reporting as Plasmodium malariae and delayed parenteral artesunate

Rajahram GS, Barber BE, William T, Menon J, Anstey NM, Yeo TW

Malar J, 2012;11:284.
PMID: 22905799 DOI: 10.1186/1475-2875-11-284

The simian parasite Plasmodium knowlesi is recognized as a common cause of severe and fatal human malaria in Sabah, Malaysia, but is morphologically indistinguishable from and still commonly reported as Plasmodium malariae, despite the paucity of this species in Sabah. Since December 2008 Sabah Department of Health has recommended intravenous artesunate and referral to a general hospital for all severe malaria cases of any species. This paper reviews all malaria deaths in Sabah subsequent to the introduction of these measures. Reporting of malaria deaths in Malaysia is mandatory.

Matched MeSH terms: Malaria/parasitology*

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