Establishing associated risk factors, including fungal and parasitic infections among Malaysians living with schizophrenia

The aetiology of schizophrenia is multifactorial, and the identification of its risk factors are scarce and highly variable. A cross-sectional study was conducted to investigate the risk factors associated with schizophrenia among Malaysian sub-population. A total of 120 individuals diagnosed with schizophrenia (SZ) and 180 non-schizophrenic (NS) individuals participated in a questionnaire-based survey. Data of complete questionnaire responses obtained from 91 SZ and 120 NS participants were used in statistical analyses. Stool samples were obtained from the participants and screened for gut parasites and fungi using conventional polymerase chain reaction (PCR). The median age were 46 years (interquartile range (IQR) 37 to 60 years) and 35 years (IQR 24 to 47.75 years) for SZ and NS respectively. Multivariable binary logistic regression showed that the factors associated with increased risk of SZ were age, sex, unemployment, presence of other chronic ailment, smoking, and high dairy consumption per week. These factors, except sex, were positively associated with the severity of SZ. Breastfed at infancy as well as vitamin and supplement consumption showed a protective effect against SZ. After data clean-up, fungal or parasitic infections were found in 98% (39/42). of SZ participants and 6.1% (3/49) of NS participants. Our findings identified non-modifiable risk factors (age and sex) and modifiable lifestyle-related risk factors (unemployment, presence of other chronic ailment, smoking, and high dairy consumption per week) associated with SZ and implicate the need for medical attention in preventing fungal and parasitic infections in SZ.

Simian malaria: a narrative review on emergence, epidemiology and threat to global malaria elimination

Simian malaria from wild non-human primate populations is increasingly recognised as a public health threat and is now the main cause of human malaria in Malaysia and some regions of Brazil. In 2022, Malaysia became the first country not to achieve malaria elimination due to zoonotic simian malaria. We review the global distribution and drivers of simian malaria and identify priorities for diagnosis, treatment, surveillance, and control. Environmental change is driving closer interactions between humans and wildlife, with malaria parasites from non-human primates spilling over into human populations and human malaria parasites spilling back into wild non-human primate populations. These complex transmission cycles require new molecular and epidemiological approaches to track parasite spread. Current methods of malaria control are ineffective, with wildlife reservoirs and primarily outdoor-biting mosquito vectors urgently requiring the development of novel control strategies. Without these, simian malaria has the potential to undermine malaria elimination globally.

Profiling the imported human malaria in Sarawak, Malaysia in 2011-2019

OBJECTIVES

Malaysia has achieved the status of zero indigenous human malaria cases. Nevertheless, imported human malaria has increasingly been reported in Sarawak, Malaysian Borneo. As zoonotic malaria caused by Plasmodium knowlesi remains a major public health problem in Sarawak, the threat of imported malaria must be addressed as it can cause human malaria reintroduction, sustain transmission, and lead to complications. The objectives of this study were to investigate the epidemiological characteristics of imported malaria cases reported in Sarawak and to underline the challenge posed by imported malaria towards malaria elimination efforts.

METHODS

Imported malaria cases reported in Sarawak from 2011 to 2019 were collected from Sarawak State Health Department and analysed in this longitudinal retrospective study.

RESULTS

A total of 2058 imported malaria cases were registered in all districts in Sarawak. Highest number of cases were reported in Kapit (n = 559; 27.16%), followed by Sibu (n = 424; 20.6%), and Miri (n = 166; 8.07%). Based on the demographic profile, most of the patients constituted of either male sex (98.49%), age group of 40-49 years (39.6%), Iban ethnic (57.92%), worked in logging industry (88.58%), Malaysian nationals (91.84%), contracted malaria in Papua New Guinea (46.11%), uncomplicated disease (77.89%), or hospitalised cases (97.86%). The most prominent Plasmodium species diagnosed were P. vivax (52.67%) and P. falciparum (35.81%).

CONCLUSIONS

Surveillance, disease detection, and medical follow-up must be carried out thoroughly for individuals who returned from malaria-endemic countries. It is also necessary to promote pre-travel preventive education as well as chemoprophylaxis to travellers heading to endemic areas.

Corrigendum: Predicting Plasmodium knowlesi transmission risk across Peninsular Malaysia using machine learning-based ecological niche modeling approaches

[This corrects the article DOI: 10.3389/fmicb.2023.1126418.].

Predicting Plasmodium knowlesi transmission risk across Peninsular Malaysia using machine learning-based ecological niche modeling approaches

The emergence of potentially life-threatening zoonotic malaria caused by Plasmodium knowlesi nearly two decades ago has continued to challenge Malaysia healthcare. With a total of 376 P. knowlesi infections notified in 2008, the number increased to 2,609 cases in 2020 nationwide. Numerous studies have been conducted in Malaysian Borneo to determine the association between environmental factors and knowlesi malaria transmission. However, there is still a lack of understanding of the environmental influence on knowlesi malaria transmission in Peninsular Malaysia. Therefore, our study aimed to investigate the ecological distribution of human P. knowlesi malaria in relation to environmental factors in Peninsular Malaysia. A total of 2,873 records of human P. knowlesi infections in Peninsular Malaysia from 1st January 2011 to 31st December 2019 were collated from the Ministry of Health Malaysia and geolocated. Three machine learning-based models, maximum entropy (MaxEnt), extreme gradient boosting (XGBoost), and ensemble modeling approach, were applied to predict the spatial variation of P. knowlesi disease risk. Multiple environmental parameters including climate factors, landscape characteristics, and anthropogenic factors were included as predictors in both predictive models. Subsequently, an ensemble model was developed based on the output of both MaxEnt and XGBoost. Comparison between models indicated that the XGBoost has higher performance as compared to MaxEnt and ensemble model, with AUC_ROC values of 0.933 ± 0.002 and 0.854 ± 0.007 for train and test datasets, respectively. Key environmental covariates affecting human P. knowlesi occurrence were distance to the coastline, elevation, tree cover, annual precipitation, tree loss, and distance to the forest. Our models indicated that the disease risk areas were mainly distributed in low elevation (75-345 m above mean sea level) areas along the Titiwangsa mountain range and inland central-northern region of Peninsular Malaysia. The high-resolution risk map of human knowlesi malaria constructed in this study can be further utilized for multi-pronged interventions targeting community at-risk, macaque populations, and mosquito vectors.

Epidemiology of indigenous Plasmodium knowlesi infection in Sarawak, 2011-2019

OBJECTIVES

To characterize the state-wide epidemiology of indigenous knowlesi malaria in Sarawak from 2011-2019.

METHODS

Longitudinal retrospective study based on Sarawak knowlesi malaria surveillance data recorded 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 to 49 years, males, plantation workers, and Iban communities recorded the highest percentage of cases in each demographic variable. Most of the cases were uncomplicated (85.9%) and 89.5% of the total cases were reported with ≤20,000 parasites/μL of blood. Age group and ethnic group are associated with 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 to 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.

Plasmodium knowlesi: the game changer for malaria eradication

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.

Genetic polymorphism of circumsporozoite protein (CSP) in Plasmodium malariae isolates from Malaysia

Information about Plasmodium malariae is scanty worldwide due to its "benign" nature and low infection rates. Consequently, studies on the genetic polymorphisms of P. malariae are lacking. Here, we report genetic polymorphisms of 28 P. malariae circumsporozoite protein (Pmcsp) isolates from Malaysia which were compared with those in other regions in Asia as well as those from Africa. Phylogenetic analysis revealed that most Malaysian P. malariae isolates clustered together but independently from other Asian isolates. Low nucleotide diversity was observed in Pmcsp non-repeat regions in contrast to high nucleotide diversity observed in non-repeat regions of Plasmodium knowlesi CSP gene, the current major cause of malaria in Malaysia. This study contributes to the characterisation of naturally occurring polymorphisms in the P. malariae CSP gene.

Natural Plasmodium inui Infections in Humans and Anopheles cracens Mosquito, Malaysia

We detected 2 natural, asymptomatic Plasmodium inui monoinfections in humans in Malaysia by using nested PCR on concentrated high-volume blood samples. We found a P. inui-positive Anopheles cracens mosquito in the same site as the human infections. Investigators should use ultrasensitive detection methods to identify simian malaria parasite transmission in humans.

Spatial and Temporal Patterns of Plasmodium knowlesi Malaria in Sarawak from 2008 to 2017

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.

Improved Aedes/dengue field surveillance using Gravid Oviposition Sticky trap and dengue NS1 tests: Epidemiological, entomological outcomes and community acceptance

The aim of this study is to investigate the feasibility and outcomes of using Gravid Oviposition Sticky (GOS) trap and dengue NS1 antigen tests for indoor and outdoor dengue/Aedes surveillance in the field. A one-year community-based study was carried out at Sungai Buloh Hospital Quarters, Selangor, Malaysia. GOS traps were first placed outdoors in three apartment blocks (Anggerik, Bunga Raya and Mawar). Beginning 29th week of the study, indoor traps were set in two apartment units on every floor in Anggerik. All female Aedes mosquitoes caught were tested for the presence of dengue NS1 antigen. Dengue seroprevalence and knowledge, attitude and practices on dengue prevention of the community and their reception to the surveillance approach were also assessed. Dengue-positive mosquitoes were detected at least 1 week before a dengue onset. More mosquitoes were caught indoors than outdoors in block Anggerik, but the total number of mosquitoes caught in all 3 blocks were similar. There was a significant difference in distribution of Ae. aegypti and Ae. albopictus between the 3 blocks. 66.1% and 3.4% of the community were positive for dengue IgG and IgM, respectively. Most respondents think that this surveillance method is Good (89%) and support its use nationwide. Dengue case ratio in the study apartment blocks decreased from year 2018 to 2019. This study demonstrated the practicality of performing proactive dengue/Aedes surveillance inside apartment units using the GOS traps. This surveillance method can be performed with immediate result output in the field.

Spatial and Temporal Analysis of Plasmodium knowlesi Infection in Peninsular Malaysia, 2011 to 2018

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 infection in Peninsular Malaysia (West Malaysia). The spatial distribution of P. knowlesi was mapped across Peninsular Malaysia using Geographic Information System techniques. Local indicators of spatial associations were used to evaluate spatial patterns of P. knowlesi incidence. Seasonal autoregressive integrated moving average models were utilized to analyze the monthly incidence of knowlesi malaria in the hotspot region from 2012 to 2017 and to forecast subsequent incidence in 2018. Spatial analysis revealed that hotspots were clustered in the central-northern region of Peninsular Malaysia. Time series analysis revealed the strong seasonality of transmission from January to March. This study provides fundamental information on the spatial distribution and temporal dynamic of P. knowlesi in Peninsular Malaysia from 2011 to 2018. Current control policy should consider different strategies to prevent the transmission of both human and zoonotic malaria, particularly in the hotspot region, to ensure a successful elimination of malaria in the future.