-
ELife May 2024Zoonotic disease dynamics in wildlife hosts are rarely quantified at macroecological scales due to the lack of systematic surveys. Non-human primates (NHPs) host a... (Meta-Analysis)
Meta-Analysis
Zoonotic disease dynamics in wildlife hosts are rarely quantified at macroecological scales due to the lack of systematic surveys. Non-human primates (NHPs) host a zoonotic malaria of public health concern and the main barrier to malaria elimination in Southeast Asia. Understanding of regional infection dynamics in wildlife is limited. Here, we systematically assemble reports of NHP and investigate geographic determinants of prevalence in reservoir species. Meta-analysis of 6322 NHPs from 148 sites reveals that prevalence is heterogeneous across Southeast Asia, with low overall prevalence and high estimates for Malaysian Borneo. We find that regions exhibiting higher prevalence in NHPs overlap with human infection hotspots. In wildlife and humans, parasite transmission is linked to land conversion and fragmentation. By assembling remote sensing data and fitting statistical models to prevalence at multiple spatial scales, we identify novel relationships between in NHPs and forest fragmentation. This suggests that higher prevalence may be contingent on habitat complexity, which would begin to explain observed geographic variation in parasite burden. These findings address critical gaps in understanding regional epidemiology and indicate that prevalence in simian reservoirs may be a key spatial driver of human spillover risk.
Topics: Animals; Humans; Asia, Southeastern; Ecosystem; Malaria; Plasmodium knowlesi; Prevalence; Primate Diseases; Primates; Zoonoses
PubMed: 38753426
DOI: 10.7554/eLife.88616 -
BMC Public Health Jan 2024Zoonotic malaria is a growing public health threat in the WHO Southeast Asia (SEA) and Western Pacific (WP) regions. Despite vector-control measures, the distribution of...
BACKGROUND
Zoonotic malaria is a growing public health threat in the WHO Southeast Asia (SEA) and Western Pacific (WP) regions. Despite vector-control measures, the distribution of Macaque fascicularis and M. nemestrina, and Anopheles mosquitoes carrying non-human simian malaria parasites poses challenges to malaria elimination. The systematic review assesses the literature on knowledge and malaria-preventive practices in zoonotic malaria-affected areas across the WHO SEA and WP, aiming to identify challenges for malaria control.
METHODS
Peer-reviewed articles published in English, Malay and Indonesian between January 2010 and December 2022 were searched in OVID Medline, Scopus, Web of Science, and Google Scholar. Studies of any design-excluding reviews, conference proceedings, and reports from all WHO SEA and WP countries vulnerable to zoonotic malaria-were included. Backwards-reference screening and thematic analysis were conducted.
RESULTS
Among 4,174 initially searched articles, 22 peer-reviewed articles met the inclusion criteria. An additional seven articles were identified through backwards-reference screening, resulting in a total of 29 articles for this review. Half of these studies were conducted in Cambodia, Myanmar, Malaysia, and Thailand, mainly in forests and remote communities. The review highlighted inconsistencies in the operationalization of knowledge, and five major themes were identified related to knowledge: causation and transmission, symptoms, treatment, severity and complications, and malaria prevention. While participants generally had some understanding of malaria causation/transmission, minority and indigenous ethnic groups demonstrated limited knowledge and held misconceptions, such as attributing malaria to drinking dirty water. Preventive practices included traditional and non-traditional or modern methods-with a preference for traditional approaches to avoid mosquito bites. Challenges to malaria control included feasibility, cost, and access to healthcare services.
CONCLUSION
This review provides insights into knowledge, local understandings, and preventive practices related to malaria in the WHO SEA and WP regions. The findings highlight the need for future research to explore the knowledge of at-risk communities regarding zoonotic malaria, their perceive threat of the disease and factors exposing them to zoonotic malaria. New strategies must be developed for zoonotic malaria programs tailored to local contexts, emphasizing the significance of community participation, health education, and socio-behavioural change initiatives. It is important to consider the interconnectedness of human health, environmental and non-human primates conservation. Socio-cultural nuances should also be carefully considered in the design and implementation of these programs to ensure their effect tailored to local contexts.
Topics: Animals; Humans; Antimalarials; Mosquito Vectors; Malaria; Asia, Southeastern; Cambodia
PubMed: 38287308
DOI: 10.1186/s12889-024-17792-8 -
Parasitology Nov 2023Of the 5 human malarial parasites, and are the most prevalent species globally, while and are less prevalent and typically occur as mixed-infections. , previously... (Review)
Review
Of the 5 human malarial parasites, and are the most prevalent species globally, while and are less prevalent and typically occur as mixed-infections. , previously considered a non-human primate (NHP) infecting species, is now a cause of human malaria in Malaysia. The other NHP species, , , , , and cause malaria in primates, which are mainly reported in southeast Asia and South America. The non- NHP species also emerged and were found to cross-transmit from their natural hosts (NHP) – to human hosts in natural settings. Here we have reviewed and collated data from the literature on the NHPs-to-human-transmitting species. It was observed that the natural transmission of these NHP parasites to humans had been reported from 2010 onwards. This study shows that: (1) the majority of the non- NHP mixed species infecting human cases were from Yala province of Thailand; (2) mono/mixed infections with other human-infecting species were prevalent in Malaysia and Thailand and (3) and were found in Central and South America.
Topics: Animals; Humans; Malaria; Plasmodium knowlesi; Primates; Asia, Southeastern; Plasmodium vivax
PubMed: 37929579
DOI: 10.1017/S003118202300077X -
The American Journal of Tropical... Jan 2023The five major Plasmodium spp. that cause human malaria appear similar under light microscopy, which raises the possibility that misdiagnosis could routinely occur in... (Meta-Analysis)
Meta-Analysis
The five major Plasmodium spp. that cause human malaria appear similar under light microscopy, which raises the possibility that misdiagnosis could routinely occur in clinical settings. Assessing the extent of misdiagnosis is of particular importance for monitoring P. knowlesi, which cocirculates with the other Plasmodium spp. We performed a systematic review and meta-analysis of studies comparing the performance of microscopy and polymerase chain reaction (PCR) for diagnosing malaria in settings with co-circulation of the five Plasmodium spp. We assessed the extent to which co-circulation of Plasmodium parasites affects diagnostic outcomes. We fit a Bayesian hierarchical latent class model to estimate variation in microscopy sensitivity and specificity measured against PCR as the gold standard. Mean sensitivity of microscopy was low, yet highly variable across Plasmodium spp., ranging from 65.7% (95% confidence interval: 48.1-80.3%) for P. falciparum to 0.525% (95% confidence interval 0.0210-3.11%) for P. ovale. Observed PCR prevalence was positively correlated with estimated microscopic sensitivity and negatively correlated with estimated microscopic specificity, though the strength of the associations varied by species. Our analysis suggests that cocirculation of Plasmodium spp. undermines the accuracy of microscopy. Sensitivity was considerably lower for P. knowlesi, P. malariae, and P. ovale. The negative association between specificity and prevalence imply that less frequently encountered species may be misdiagnosed as more frequently encountered species. Together, these results suggest that the burden of P. knowlesi, P. malariae, and P. ovale may be underappreciated in a clinical setting.
Topics: Humans; Bayes Theorem; Malaria; Malaria, Falciparum; Microscopy; Plasmodium knowlesi; Polymerase Chain Reaction; Communicable Diseases, Emerging; Coinfection; Diagnostic Errors; Plasmodium ovale; Plasmodium malariae
PubMed: 36509046
DOI: 10.4269/ajtmh.21-1155 -
Malaria Journal Dec 2022In the last decade Plasmodium knowlesi has been detected in humans throughout South East Asia. The highest risk groups for this infection are males, adults and those... (Review)
Review
BACKGROUND
In the last decade Plasmodium knowlesi has been detected in humans throughout South East Asia. The highest risk groups for this infection are males, adults and those performing forest-related work. Furthermore, asymptomatic cases of P. knowlesi malaria have been reported including among women and children.
METHODS
Pubmed, Scopus and the Web of Science databases for literature describing asymptomatic P. knowlesi malaria published between 2010 and 2020 were searched. A systematic literature review was conducted to identify studies reporting the prevalence and incidence of laboratory confirmed asymptomatic P. knowlesi cases in humans, their clinical and demographic characteristics, and methods used to diagnose these cases.
RESULTS
By analysing over 102 papers, thirteen were eligible for this review. Asymptomatic P. knowlesi infections have been detected in 0.03%-4.0% of the population depending on region, and infections have been described in children as young as 2 years old. Various different diagnostic methods were used to detect P. knowlesi cases and there were differing definitions of asymptomatic cases in these studies. The literature indicates that regionally-differing immune-related mechanisms may play a part on the prevalence of asymptomatic P. knowlesi.
CONCLUSION
Differing epidemiological characteristics of asymptomatic P. knowlesi malaria in different regions reinforces the need to further investigate disease transmission mechanics. Effective public health responses to changes in P. knowlesi epidemiology require proactive intervention and multisectoral collaboration.
Topics: Child; Humans; Female; Child, Preschool; Plasmodium knowlesi; Communicable Diseases, Emerging
PubMed: 36474243
DOI: 10.1186/s12936-022-04339-8 -
Parasites & Vectors Dec 2022The production of Plasmodium gametocytes in vitro is a real challenge. Many protocols have been described, but few have resulted in the production of viable and... (Review)
Review
BACKGROUND
The production of Plasmodium gametocytes in vitro is a real challenge. Many protocols have been described, but few have resulted in the production of viable and infectious gametocytes in sufficient quantities to conduct research on-but not limited to-transmission-blocking drug and vaccine development. The aim of this review was to identify and discuss gametocyte production protocols that have been developed over the last two decades.
METHODS
We analyzed the original gametocyte production protocols published from 2000 onwards based on a literature search and a thorough review. A systematic review was performed of relevant articles identified in the PubMed, Web of Sciences and ScienceDirect databases.
RESULTS
A total 23 studies on the production of Plasmodium gametocytes were identified, 19 involving in vitro Plasmodium falciparum, one involving Plasmodium knowlesi and three involving ex vivo Plasmodium vivax. Of the in vitro studies, 90% used environmental stressors to trigger gametocytogenesis. Mature gametocytemia of up to 4% was reported.
CONCLUSIONS
Several biological parameters contribute to an optimal production in vitro of viable and infectious mature gametocytes. The knowledge gained from this systematic review on the molecular mechanisms involved in gametocytogenesis enables reproducible gametocyte protocols with transgenic parasite lines to be set up. This review highlights the need for additional gametocyte production protocols for Plasmodium species other than P. falciparum.
Topics: Humans; Malaria, Falciparum; Plasmodium falciparum; Plasmodium knowlesi; Plasmodium vivax; Systematic Reviews as Topic
PubMed: 36471426
DOI: 10.1186/s13071-022-05566-3 -
Parasites & Vectors Jul 2022The Indonesian Republic plans to relocate its capital from Jakarta to East Kalimantan, Borneo Island, in the next few years. This relocation may be associated with...
BACKGROUND
The Indonesian Republic plans to relocate its capital from Jakarta to East Kalimantan, Borneo Island, in the next few years. This relocation may be associated with deforestation, decreased biodiversity, and an increased risk of emerging zoonotic infections, including Plasmodium knowlesi malaria. The Malaysian part of Borneo Island is one of the main hotspots of P. knowlesi malaria.
METHODS
Considering this risk, we evaluated the transmission dynamics of P. knowlesi in the Indonesian Archipelago based on a literature search and extensive review of data from the Indonesian Ministry of Health.
RESULTS
We report that 545 P. knowlesi cases were documented in Indonesia, mainly in the Aceh and North Sumatra provinces, with 95% of these occurring in the last 4 years.
CONCLUSIONS
The main P. knowlesi vectors are present in the area of the future capital, requiring strengthened surveillance to reduce the risk of emerging cases in a rapidly growing population.
Topics: Animals; Humans; Borneo; Indonesia; Malaria; Malaysia; Plasmodium knowlesi; Zoonoses
PubMed: 35850777
DOI: 10.1186/s13071-022-05375-8 -
PLoS Neglected Tropical Diseases Jul 2022The aim of Malaysia to eliminate malaria nationwide by 2020 seems need to be prolonged. Whilst Malaysia has successfully eliminated human malaria transmission, simian...
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.
Topics: Animals; Humans; Macaca; Malaria; Malaysia; Parasites; Plasmodium knowlesi; Prevalence
PubMed: 35849568
DOI: 10.1371/journal.pntd.0010527 -
International Journal of Environmental... Mar 2022is a non-human parasite that causes zoonotic disease in humans. This systematic review aims to highlight and summarize studies describing human behaviors and activities... (Review)
Review
OBJECTIVES
is a non-human parasite that causes zoonotic disease in humans. This systematic review aims to highlight and summarize studies describing human behaviors and activities that expose humans to mosquito bites. English entries in PubMed, Web of Science, and Science Direct from 2010 to 2020 were systematically perused, and the results were synthesized. Methodological quality was assessed using the Joanna Briggs Institute quality appraisal checklists.
SETTING
Studies that described malaria preventive measures were included. Laboratory, in vivo, in vitro, and animal studies were excluded.
PRIMARY AND SECONDARY OUTCOME MEASURES
The main outcome of the review was findings from studies describing the behavior that exposed a person or a group to infection.
RESULTS
Twelve eligible studies were of good or medium quality. Attitude, disease misconceptions, perceived threat of disease, lack of motivation, and supernatural or traditional beliefs causing individuals to seek treatment from traditional healers influenced the exposure of individuals or communities to malaria. Other factors were forestry activities (2.48, 1.45-4.23,95% CI, = 0.0010) and sleeping outdoors (3.611, 1.48-8.85, 95% CI, = 0.0049).
CONCLUSIONS
Future studies must consider the importance of human behavior and community perspective on the infection to provide novel information to improve the current zoonotic malaria programs. Policymakers should concentrate on understanding human behavior and activities that expose individuals or communities to mosquito bites, in order to better design socially feasible interventions.
Topics: Animals; Humans; Insect Bites and Stings; Malaria; Motivation; Plasmodium knowlesi; Zoonoses
PubMed: 35329359
DOI: 10.3390/ijerph19063675 -
Malaria Journal Mar 2022The zoonotic malaria parasite Plasmodium knowlesi has emerged across Southeast Asia and is now the main cause of malaria in humans in Malaysia. A critical priority for...
BACKGROUND
The zoonotic malaria parasite Plasmodium knowlesi has emerged across Southeast Asia and is now the main cause of malaria in humans in Malaysia. A critical priority for P. knowlesi surveillance and control is understanding whether transmission is entirely zoonotic or is also occurring through human-mosquito-human transmission.
METHODS
A systematic literature review was performed to evaluate existing evidence which refutes or supports the occurrence of sustained human-mosquito-human transmission of P. knowlesi. Possible evidence categories and study types which would support or refute non-zoonotic transmission were identified and ranked. A literature search was conducted on Medline, EMBASE and Web of Science using a broad search strategy to identify any possible published literature. Results were synthesized using the Synthesis Without Meta-analysis (SWiM) framework, using vote counting to combine the evidence within specific categories.
RESULTS
Of an initial 7,299 studies screened, 131 studies were included within this review: 87 studies of P. knowlesi prevalence in humans, 14 studies in non-human primates, 13 studies in mosquitoes, and 29 studies with direct evidence refuting or supporting non-zoonotic transmission. Overall, the evidence showed that human-mosquito-human transmission is biologically possible, but there is limited evidence of widespread occurrence in endemic areas. Specific areas of research were identified that require further attention, notably quantitative analyses of potential transmission dynamics, epidemiological and entomological surveys, and ecological studies into the sylvatic cycle of the disease.
CONCLUSION
There are key questions about P. knowlesi that remain within the areas of research that require more attention. These questions have significant implications for malaria elimination and eradication programs. This paper considers limited but varied research and provides a methodological framework for assessing the likelihood of different transmission patterns for emerging zoonotic diseases.
Topics: Animals; Asia, Southeastern; Culicidae; Humans; Malaria; Plasmodium knowlesi; Zoonoses
PubMed: 35300703
DOI: 10.1186/s12936-022-04110-z