Peninsular Malaysia map showing states (divided into administrative levels of district) and federal territories.

Peninsular Malaysia map showing states (divided into administrative levels of district) and federal territories.

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The life-threatening zoonotic malaria cases caused by Plasmodium knowlesi in Malaysia has recently been reported to be the highest among all malaria cases; however, previous studies have mainly focused on the transmission of P. knowlesi in Malaysian Borneo (East Malaysia). This study aimed to describe the transmission patterns of P. knowlesi infect...

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... study area primarily focused on Peninsular Malaysia which spreads from latitude 1 • 15 50.0 N to 6 • 43 36 N and from longitude 99 • 35 E to 104 • 36 E. Peninsular Malaysia covers a land area of 13.21 million hectares (Figure 1) [18]. Forested areas account for approximately 5.76 million hectares, which is equivalent to 43.6% of the land area of Peninsular Malaysia [18]. ...
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... mean daily temperature ranges from 25 to 28 °C. Peninsular Malaysia is divided into 11 states (Perlis, Kedah, Pulau Pinang, Perak, Selangor, Negeri Sembilan, Melaka, Johor, Kelantan, Terengganu, and Pahang) and 2 federal territories (Kuala Lumpur and Putrajaya) (Figure 1). Approximately 24.7% of the population of Peninsular Malaysia reside in sub-urban and rural areas. ...
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... indigenous malaria case is a case contracted locally with no evidence of importation and no direct link to transmission from an imported case, whereas an imported malaria is a case in which the infection was acquired outside the area in which it was diagnosed [22]. The case Peninsular Malaysia is divided into 11 states (Perlis, Kedah, Pulau Pinang, Perak, Selangor, Negeri Sembilan, Melaka, Johor, Kelantan, Terengganu, and Pahang) and 2 federal territories (Kuala Lumpur and Putrajaya) (Figure 1). Approximately 24.7% of the population of Peninsular Malaysia reside in sub-urban and rural areas. ...
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... number of indigenous P. knowlesi cases was apparently higher than other indigenous human malaria cases (P. malariae, P. falciparum, and P. vivax) in most years except 2011 and 2016 ( Figure A1). Although fewer females were infected with P. knowlesi as compared to males, female patients (median 39 years, interquartile range 23-52 years) were generally older than the males (median 34 years, interquartile range 25.5-45 years). ...

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... Furthermore, the influx of migrant workers from malaria-endemic countries and challenges of drug resistance have exacerbated the risk of re-emergence of the disease. Due to the large-scale clearing of forest areas for logging and agricultural purposes, Malaysia faces the problem of increasing cases of simian malaria driven by the migration of macaques to human settlements, particularly in the remote areas where the aboriginal populations live [3,5,8,10]. Although Malaysia has been recognized as one of the countries free from indigenous human malaria since 2018 [1], it is essential to acknowledge the prevalence of non-human malaria and strengthen the effectiveness of the national elimination program. ...
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Malaria remains a public health problem in many parts of the world, including Malaysia. Although Malaysia has been recognized as one of the countries free from indigenous human malaria since 2018, the rising trend of zoonotic malaria, particularly Plasmodium knowlesi cases, poses a threat to public health and is of great concern to the country’s healthcare system. We reviewed previously scattered information on zoonotic malaria infections in both Peninsular Malaysia and Malaysian Borneo to determine the epidemiology and distribution of emerging zoonotic malaria infections. Given the high prevalence of zoonotic malaria in Malaysia, efforts should be made to detect zoonotic malaria in humans, mosquito vectors, and natural hosts to ensure the success of the National Malaria Elimination Strategic Plan.
... From 2011 to 2019, 36.6% (189) of all malaria cases reported in Johor were caused by P. knowlesi. As the human malaria cases reduced over the years, the cases of P. knowlesi malaria have increased in Peninsular Malaysia [31]. Thus, the distribution and bionomics of simian malaria vectors are significant aspects required for zoonotic malaria prevention. ...
... This kind of landscape provides clean and suitable water bodies for the breeding of the Anopheles mosquitoes. Based on previous studies [31,41,42], the current results concur that people working in the jungle like police or army and people involved in the agricultural sector were more likely to be exposed to the infection than other occupations. The number of males infected with knowlesi malaria was higher than the female because of their type of profession. ...
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Background Plasmodium knowlesi, a simian malaria parasite infection, increases as Plasmodium falciparum and Plasmodium vivax infections decrease in Johor, Malaysia. Therefore, this study aimed to identify the distribution of vectors involved in knowlesi malaria transmission in Johor. This finding is vital in estimating hotspot areas for targeted control strategies. Methods Anopheles mosquitoes were collected from the location where P. knowlesi cases were reported. Cases of knowlesi malaria from 2011 to 2019 in Johor were analyzed. Internal transcribed spacers 2 ( ITS2 ) and cytochrome c oxidase subunit I ( COI ) genes were used to identify the Leucosphyrus Group of Anopheles mosquitoes. In addition, spatial analysis was carried out on the knowlesi cases and vectors in Johor. Results One hundred and eighty-nine cases of P. knowlesi were reported in Johor over 10 years. Young adults between the ages of 20–39 years comprised 65% of the cases. Most infected individuals were involved in agriculture and army-related occupations (22% and 32%, respectively). Four hundred and eighteen Leucosphyrus Group Anopheles mosquitoes were captured during the study. Anopheles introlatus was the predominant species, followed by Anopheles latens . Spatial analysis by Kriging interpolation found that hotspot regions of P. knowlesi overlapped or were close to the areas where An. introlatus and An. latens were found. A significantly high number of vectors and P. knowlesi cases were found near the road within 0–5 km. Conclusions This study describes the distribution of P. knowlesi cases and Anopheles species in malaria-endemic transmission areas in Johor. Geospatial analysis is a valuable tool for studying the relationship between vectors and P. knowlesi cases. This study further supports that the Leucosphyrus Group of mosquitoes might be involved in transmitting knowlesi malaria cases in Johor. These findings may provide initial evidence to prioritize diseases and vector surveillance.
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Background The aim of Malaysia to eliminate malaria nationwide by 2020 seems need to be prolonged. Whilst Malaysia has successfully eliminated human malaria transmission, simian malaria parasites such as Plasmodium knowlesi , P . cynomolgi , P . inui and P . cynomolgi are the emerging cause of malaria in humans. The epidemiological study of simian malaria in primates provides useful information in identifying the risk of human-macaques Plasmodium infection. Methodology/Principal findings This study was performed to gather all available data in terms of simian malaria epidemiology study among macaques in Malaysia over the last two decades. This systematic review was conducted according to the PRISMA guidelines to select appropriate articles as references. Data searches were performed through international databases such as Google Scholar, PubMed, CrossRef, Scopus, Web of Science and Science Direct for original articles published from 2000 until 2021. The review identified seven simian malaria epidemiology studies in Malaysia over the 20-year study period. Most studies were conducted in Peninsular Malaysia (5/7; 71%) followed by East Malaysia (2/7; 29%). All studies showed positive detection of Plasmodium parasites in macaques. The most prevalent Plasmodium species in macaques was P . inui (49.27%) and the least prevalent was P . fieldi (4.76%). The prevalence of simian malaria was higher in East Malaysia compared to Peninsular Malaysia. The mono, dual and triple infection types were the most common among macaques. Conclusion/Significance The non-human primates like macaques are the reservoir of simian plasmodium in Malaysia. Hence, the study of host epidemiology is an important insight to public health management as there is a high occurrence of simian malaria in Malaysia. The right measurement can be taken as well to prevent the transmission of simian malaria from macaques to humans.
Article
Objectives: To characterise the state-wide epidemiology of indigenous knowlesi malaria in Sarawak from 2011 to 2019. Methods: Longitudinal retrospective study was conducted based on Sarawak knowlesi malaria surveillance data recorded from 2011-2019. Only indigenous cases were included and information extracted for analysis comprised age, sex, occupation, ethnicity, case severity, hospital admission and parasite density. Results: Over the 9 years, 8473 indigenous knowlesi malaria cases were recorded. Age group 40-49 years, males, plantation workers and Iban communities recorded the highest percentage of cases in each demographic variable. Most of the cases were uncomplicated (n = 7292; 86.1%) and 89.6% (n = 7589) of the total cases were reported with ≤20 000 parasites/μl of blood. Age group and ethnic group are associated with the severity of knowlesi malaria in Sarawak. Multivariable logistic regression indicated that the age group 60+ years had the highest odds of developing severe knowlesi malaria compared with other age groups (AOR 2.48; 95% CI 1.22, 5.02; p = 0.012). Bidayuh patients were more likely to develop severe knowlesi malaria than Ibans, the largest ethnic group among knowlesi malaria patients (AOR 1.97; 95% CI 1.31, 2.97; p = 0.001). Conclusions: Identification of risk groups is important for the implementation of prevention programs and treatments targeting at specific group to combat knowlesi malaria effectively.
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Plasmodium knowlesi is a zoonotic malaria parasite that has gained increasing medical interest over the past two decades. This zoonotic parasitic infection is prevalent in Southeast Asia and causes many cases with fulminant pathology. Despite several biogeographical restrictions that limit its distribution, knowlesi malaria cases have been reported in different parts of the world due to travelling and tourism activities. Here, breakthroughs and key information generated from recent (over the past five years, but not limited to) studies conducted on P. knowlesi were reviewed, and the knowledge gap in various research aspects that need to be filled was discussed. Besides, challenges and strategies required to control and eradicate human malaria with this emerging and potentially fatal zoonosis were described.
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The global malaria burden sometimes obscures that the genus Plasmodium comprises diverse clades with lineages that independently gave origin to the extant human parasites. Indeed, the differences between the human malaria parasites were highlighted in the classical taxonomy by dividing them into two subgenera, the subgenus Plasmodium , which included all the human parasites but Plasmodium falciparum that was placed in its separate subgenus, Laverania . Here, the evolution of Plasmodium in primates will be discussed in terms of their species diversity and some of their distinct phenotypes, putative molecular adaptations, and host–parasite biocenosis. Thus, in addition to a current phylogeny using genome-level data, some specific molecular features will be discussed as examples of how these parasites have diverged. The two subgenera of malaria parasites found in primates, Plasmodium and Laverania , reflect extant monophyletic groups that originated in Africa. However, the subgenus Plasmodium involves species in Southeast Asia that were likely the result of adaptive radiation. Such events led to the Plasmodium vivax lineage. Although the Laverania species, including P. falciparum , has been considered to share “avian characteristics,” molecular traits that were likely in the common ancestor of primate and avian parasites are sometimes kept in the Plasmodium subgenus while being lost in Laverania . Assessing how molecular traits in the primate malaria clades originated is a fundamental science problem that will likely provide new targets for interventions. However, given that the genus Plasmodium is paraphyletic (some descendant groups are in other genera), understanding the evolution of malaria parasites will benefit from studying “non- Plasmodium ” Haemosporida.
Chapter
Within the past two decades, incidence of human cases of the zoonotic malaria Plasmodium knowlesi has increased markedly. P. knowlesi is now the most common cause of human malaria in Malaysia and threatens to undermine malaria control programmes across Southeast Asia. The emergence of zoonotic malaria corresponds to a period of rapid deforestation within this region. These environmental changes impact the distribution and behaviour of the simian hosts, mosquito vector species and human populations, creating new opportunities for P. knowlesi transmission. Here, we review how landscape changes can drive zoonotic disease emergence, examine the extent and causes of these changes across Southeast and identify how these mechanisms may be impacting P. knowlesi dynamics. We review the current spatial epidemiology of reported P. knowlesi infections in people and assess how these demographic and environmental changes may lead to changes in transmission patterns. Finally, we identify opportunities to improve P. knowlesi surveillance and develop targeted ecological interventions within these landscapes.
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Background Vector surveillance is essential in determining the geographical distribution of mosquito vectors and understanding the dynamics of malaria transmission. With the elimination of human malaria cases, knowlesi malaria cases in humans are increasing in Malaysia. This necessitates intensive vector studies using safer trapping methods which are both field efficient and able to attract the local vector populations. Thus, this study evaluated the potential of Mosquito Magnet as a collection tool for Anopheles mosquito vectors of simian malaria along with other known collection methods. Methods A randomized 4 × 4 Latin square designed experiment was conducted to compare the efficiency of the Mosquito Magnet against three other common trapping methods: human landing catch (HLC), CDC light trap and human baited trap (HBT). The experiment was conducted over six replicates where sampling within each replicate was carried out for 4 consecutive nights. An additional 4 nights of sampling was used to further evaluate the Mosquito Magnet against the “gold standard” HLC. The abundance of Anopheles sampled by different methods was compared and evaluated with focus on the Anopheles from the Leucosphyrus group, the vectors of knowlesi malaria. Results The Latin square designed experiment showed HLC caught the greatest number of Anopheles mosquitoes ( n = 321) compared to the HBT ( n = 87), Mosquito Magnet ( n = 58) and CDC light trap ( n = 13). The GLMM analysis showed that the HLC method caught significantly more Anopheles mosquitoes compared to Mosquito Magnet ( P = 0.049). However, there was no significant difference in mean nightly catch of Anopheles mosquitoes between Mosquito Magnet and the other two trapping methods, HBT ( P = 0.646) and CDC light traps ( P = 0.197). The mean nightly catch for both An. introlatus (9.33 ± 4.341) and An. cracens (4.00 ± 2.273) caught using HLC was higher than that of Mosquito Magnet, though the differences were not statistically significant ( P > 0.05). This is in contrast to the mean nightly catch of An. sinensis (15.75 ± 5.640) and An. maculatus (15.78 ± 3.479) where HLC showed significantly more mosquito catches compared to Mosquito Magnet ( P < 0.05). Conclusions Mosquito Magnet has a promising ability to catch An. introlatus and An. cracens , the important vectors of knowlesi and other simian malarias in Peninsular Malaysia. The ability of Mosquito Magnet to catch some of the Anopheles mosquito species is comparable to HLC and makes it an ethical and safer alternative. Graphic Abstract
Article
Zoonotic knowlesi malaria has replaced human malaria as the most prevalent malaria disease in Malaysia. The persistence of knowlesi malaria in high-risk transmission areas or hotspots can be discouraging to existing malaria elimination efforts. In this study, retrospective data of laboratory-confirmed knowlesi malaria cases were obtained from the Sarawak Health Department to investigate the spatiotemporal patterns and clustering of knowlesi malaria in the state of Sarawak from 2008 to 2017. Purely spatial, purely temporal, and spatiotemporal analyses were performed using SaTScan software to define clustering of knowlesi malaria incidence. Purely spatial and spatiotemporal analyses indicated most likely clusters of knowlesi malaria in the northern region of Sarawak, along the Sarawak–Kalimantan border, and the inner central region of Sarawak between 2008 and 2017. Temporal cluster was detected between September 2016 and December 2017. This study provides evidence of the existence of statistically significant Plasmodium knowlesi malaria clusters in Sarawak, Malaysia. The analysis approach applied in this study showed potential in establishing surveillance and risk management system for knowlesi malaria control as Malaysia approaches human malaria elimination.