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.
METHODS: An outbreak was declared following the detection of P. malariae in July 2020 and active case detection for malaria was performed by collecting blood samples from residents residing within 2 km radius of Moyog village. Vector prevalence and the efficacy of residual insecticides were determined. Health awareness programmes were implemented to prevent future outbreaks. A survey was conducted among villagers to understand risk behaviour and beliefs concerning malaria.
RESULTS: A total of 5254 blood samples collected from 19 villages. Among them, 19 P. malariae cases were identified, including the index case, which originated from a man who returned from Indonesia. His return from Indonesia and healthcare facilities visit coincided with the movement control order during COVID-19 pandemic when the healthcare facilities stretched its capacity and only serious cases were given priority. Despite the index case being a returnee from a malaria endemic area presenting with mild fever, no malaria test was performed at local healthcare facilities. All cases were symptomatic and uncomplicated except for a pregnant woman with severe malaria. There were no deaths; all patients recovered following treatment with artemether-lumefantrine combination therapy. Anopheles balabacensis and Anopheles barbirostris were detected in ponds, puddles and riverbeds. The survey revealed that fishing and hunting during night, and self-treatment for mild symptoms contributed to the outbreak. Despite the index case being a returnee from a malaria-endemic area presenting with mild fever, no malaria test was performed at local healthcare facilities.
CONCLUSION: The outbreak occurred during a COVID-19 movement control order, which strained healthcare facilities, prioritizing only serious cases. Healthcare workers need to be more aware of the risk of malaria from individuals who return from malaria endemic areas. To achieve malaria elimination and prevention of disease reintroduction, new strategies that include multisectoral agencies and active community participation are essential for a more sustainable malaria control programme.
METHODS: The suitability of the polymorphic P. falciparum histidine-rich protein 2 (pfhrp2) gene was assessed to serve as an alternative marker using a PCR-sequencing or a PCR-RFLP protocol for genotyping of samples in drug efficacy clinical trials. The value of pfhrp2 was validated by side-by-side analyses of 5 admission-recrudescence sample pairs from Yemeni malaria patients.
RESULTS: The outcome of the single pfhrp2 gene discrimination analysis has been found consistent with msp1, msp2 and glurp pool genotyping analysis for the differentiation of recrudescence from new infection.
CONCLUSION: The findings suggest that under the appropriate circumstances, pfhrp2 can serve as an additional molecular marker for monitoring anti-malarials efficacy. However, its use is restricted to endemic areas where only a minority of P. falciparum parasites lack the pfhrp2 gene.
METHODS: In 2013, a total of 1744 dried blood spots (DBS) were obtained from residents of 8 longhouses who appeared healthy. Subsequently, 251 venous blood samples were collected from residents of 2 localities in 2014 based on the highest number of submicroscopic cases from prior findings. Thin and thick blood films were prepared from blood obtained from all participants in this study. Microscopic examination were carried out on all samples and a nested and nested multiplex PCR were performed on samples collected in 2013 and 2014 respectively.
RESULTS: No malaria parasites were detected in all the Giemsa-stained blood films. However, of the 1744 samples, 29 (1.7%) were positive for Plasmodium vivax by PCR. Additionally, of the 251 samples, the most prevalent mono-infection detected by PCR was Plasmodium falciparum 50 (20%), followed by P. vivax 39 (16%), P. knowlesi 9 (4%), and mixed infections 20 (8%).
CONCLUSIONS: This research findings conclude evidence of Plasmodium by PCR, among samples previously undetectable by routine blood film microscopic examination, in local ethnic minority who are clinically healthy. SMM in Belaga district is attributed not only to P. vivax, but also to P. falciparum and P. knowlesi. In complementing efforts of programme managers, there is a need to increase surveillance for SMM nationwide to estimate the degree of SMM that warrant measures to block new transmission of malaria.
MAIN TEXT: Plasmodium knowlesi is the most common cause of malaria in Malaysia, and cases have also been reported in nearly all countries of Southeast Asia. Outside of Malaysia, P. knowlesi is frequently misdiagnosed by microscopy as Plasmodium falciparum or Plasmodium vivax. Thus, P. knowlesi may be underdiagnosed in affected regions and its true incidence underestimated. Acknowledgement in the World Malaria Report of the regional importance of P. knowlesi will facilitate efforts to improve surveillance of this emerging parasite. Furthermore, increased recognition will likely lead to improved delivery of effective treatment for this potentially fatal infection, as has occurred in Malaysia where P. knowlesi case-fatality rates have fallen despite rising incidence. In a number of knowlesi-endemic countries, substantial progress has been made towards the elimination of P. vivax and P. falciparum. However, efforts to eliminate these human-only species should not preclude efforts to reduce human malaria from P. knowlesi. The regional importance of knowlesi malaria was recognized by the WHO with its recent Evidence Review Group meeting on knowlesi malaria to address strategies for prevention and mitigation.
CONCLUSION: The WHO World Malaria Report has an appropriate focus on falciparum and vivax malaria, the major causes of global mortality and morbidity. However, the authors hope that in future years this important publication will also incorporate data on the progress and challenges in reducing knowlesi malaria in regions where transmission occurs.
CASE PRESENTATION: A 61 years old asplenic man was admitted to a tertiary referral hospital in Sabah, Malaysia, with severe knowlesi malaria characterized by hyperparasitaemia (7.9 %), jaundice, respiratory distress, metabolic acidosis, and acute kidney injury. He was commenced on intravenous artesunate, but1 day later developed haemoglobinuria, associated with a 22 % reduction in admission haemoglobin. Additional investigations, including a cell-free haemoglobin of 10.2 × 10(5) ng/mL and an undetectable haptoglobin, confirmed intravascular haemolysis. The patient continued on intravenous artesunate for a total of 48 h prior to substitution with artemether-lumefantrine, and made a good recovery with resolution of his haemoglobinuria and improvement of his kidney function by day 3.
CONCLUSIONS: An asplenic patient with hyperparasitaemic severe knowlesi malaria developed haemoglobinuria after treatment with intravenous artesunate. There are plausible mechanisms for increased haemolysis with hyperparasitaemia, and following both splenectomy and artesunate. Although in this case the patient made a rapid recovery, knowlesi malaria patients with this unusual complication should be closely monitored for potential deterioration.
METHODS: A clinical efficacy study of oral artesunate (total target dose 12 mg/kg) daily for 3 days was conducted in patients with uncomplicated falciparum malaria and a parasite count
METHODS: This was a randomized controlled parallel-group trial in which 372 antenatal care attendees were randomly assigned to either an intervention or control group after collecting baseline data using a structured questionnaire. The intervention group received a 4-h health education on malaria, guided by a module developed based on the IMB theory, while the control group received health education on breastfeeding for a similar duration and by the same facilitator. Follow-up data were subsequently collected at 2 months and at 4 months post-intervention using the same questionnaire. The generalized linear mixed models analysis was used to determine the between-group and within-group effects of the intervention. The intention-to-treat analysis was used after missing data had been replaced. This was followed by a sensitivity analysis, where the analyses were repeated without replacing the missing values.
RESULTS: The intervention was significant in achieving a 12.75% (p
METHODS: The study utilized a cross-sectional study design, using a structured and pre-tested questionnaire to obtain information from 380 respondents. Respondents were classified as ITN users if they slept under an ITN for at least 3 days in a week, while those who did not at all, or slept under it less frequently were classified as ITN non-users. Chi squared test was performed to test the bivariate association between ITN use and each of the items of the questionnaire. A further multivariate logistic regression was performed to determine the predictors of ITN use.
RESULTS: The respondents' ages ranged from 15 to 45 years, with median (interquartile range) age of 25 (8) years. Eighty percent of them were aware of ITN, but 50.5% believed ITNs could be dangerous. Only 5.5% and 0.8% respectively felt that sleeping under and ITN was either just bad or very bad for their health. Thirty-five percent of the respondents were ITN users. Not having a previous miscarriage (OR = 2.38; 95% CI 1.41-4.03, p = 0.001), knowledge that ITNs were not to be washed after every 1 month (OR = 3.60; 95% CI 1.18-11.06), significant others thinking they should sleep under an ITN (OR = 3.06; 95% CI 1.35-6.96), ability to effectively persuade others to sleep under an ITN (OR = 2.37; 95% CI 1.14-4.94) were significantly associated with ITN use.
CONCLUSIONS: A large proportion of pregnant women in this study were not sleeping under ITNs. The development of health promotion interventions aimed at boosting their self-efficacies for ITN use, and improving social support from their spouses are, therefore, recommended. Health education on ITN use should also be incorporated into post-abortal management.
METHODS: The study was a randomized controlled parallel-group study, where 372 randomly selected antenatal care attendees were randomly assigned to one of either two groups after collecting baseline data. The intervention group then received a four-hour health education intervention in Hausa language, which was developed based on the IMB model, while the control group received a similarly designed health education on breastfeeding. Follow up data were then collected from the participants at a first (2 months post-intervention) and second (4 months post-intervention) follow up, and at the end of their pregnancies.
RESULTS: For both groups, reported ITN use had increased from baseline (Intervention: Often-14.0%, Almost always-9.1; Control: Often-12.4%; Almost always 16.1%) to the time of second follow up (Intervention: Often -28.10%, Almost always-24.5; Control: Often-17.2%; Almost always 19.5%). Reported IPTp uptake at second follow up was also higher for the intervention group (Intervention: Two doses-59.0%, Three doses 22.3%; Control group: Two doses-48.4%, Three doses-7.0%). The drop in the haematocrit levels was greater for the control group (32.42% to 30.63%) compared to the intervention group (33.09% to 31.93%). The Generalized Linear Mixed Models (GLMM) analysis revealed that the intervention had significantly improved reported ITN use, reported IPTp uptake, and haematocrit levels, but had no significant effect on the incidence of reported malaria diagnosis or babies' birth weights.
CONCLUSIONS: The intervention was effective in improving ITN use, IPTp uptake, and haematocrit levels. It is, therefore, recommended for the modules to be adopted and incorporated into the routine antenatal care programmes in health centres with predominantly Hausa speaking clients.
TRIAL REGISTRATION: Pan African Clinical Trial Registry, PACTR201610001823405. Registered 26 October 2016, www.pactr.org .
METHODS: Relevant case-control studies that assessed the association between TLR 4/9 and malaria either in susceptibility or progression were searched in health-related electronic databases. Quality of included studies was evaluated with Newcastle-Ottawa scale. Pooled analyses for specific genetic polymorphisms were done under five genetic models. Stratified analysis was done by age and geographical region (Asian countries vs non-Asian countries).
RESULTS: Eleven studies (2716 cases and 2376 controls) from nine endemic countries were identified. Five studies (45.4%) obtained high score in quality assessment. Overall, a significant association between TLR9 (T1486C) and severity of malaria is observed in allele model (OR: 1.26, 95% CI: 1.08-1.48, I2 = 0%) or homozygous model (OR: 1.55, 95% CI: 1.08-2.28, I2 = 0%). For TLR9 (T1237C), a significant association with severity of malaria is observed in in heterozygous model (OR:1.89, 95% CI: 1.11-3.22, I2 = 75%). On stratifications, TLR9 (T1486C) is only significantly associated with a subgroup of children of non-Asian countries under allele model (OR: 1.25, 95% CI: 1.02-1.38), while 1237 is with a subgroup of adults from Asian countries under heterozygous model (OR: 2.0, 95% CI: 1.09-3.64, I2 = 39%). Regarding the susceptibility to malaria, TLR9 (T1237C) is significantly associated only with the children group under recessive model (OR: 2.21, 95% CI: 1.06-4.57, I2=85%) and homozygous model (OR: 1.49, 95% CI: 1.09-2.0, I2 = 0%). For TLR4 (D299G, T399I), none is significantly associated with either severity of malaria or susceptibility to malaria under any genetic models.
CONCLUSIONS: The findings suggest that TLR 9 (T1486C and T1237C) seems to influence the progression of malaria, under certain genetic models and in specific age group of people from specific geographical region. TLR 9 (T1237C) also plays a role in susceptibility to malaria under certain genetic models and only with children of non-Asian countries. To substantiate these, future well designed studies with larger samples across endemic countries are needed.
CASE PRESENTATION: A 23-year old splenectomized patient with beta thalassaemia major presented with fever 11 days after receiving a blood transfusion from a pre-symptomatic donor who presented with knowlesi malaria 12 days following blood donation. The infection resulted in severe disease in the recipient, with a parasite count of 84,000/µL and associated metabolic acidosis and multi-organ failure. She was treated with intravenous artesunate and made a good recovery. Sequencing of a highly diverse 649-base pair fragment of the P. knowlesi bifunctional dihydrofolate reductase-thymidylate synthase gene (pkdhfr) revealed that the recipient and donor shared the same haplotype.
CONCLUSIONS: This case demonstrates that acquisition of P. knowlesi from blood transfusion can occur, and that clinical consequences can be severe. Furthermore, this case raises the possibility that thalassaemic patients, particularly those who are splenectomized, may represent a high-risk group for TTM and severe malaria. With rising P. knowlesi incidence, further studies in Sabah are required to determine the risk of TTM in order to guide screening strategies for blood transfusion services.
METHODS: Plasmodium berghei infection in male ICR mice was used as the rodent model of choice. The time course of IL-35 expression in the systemic circulation and tissues of P. berghei infected mice as well as their healthy control counterparts was assessed by enzyme linked immunosorbent assay and immunohistochemistry respectively. The effect of modulating IL-35 by recombinant IL-35 protein or neutralizing anti-Epstein-Barr virus-induced gene 3 antibody on the cytokine environment during P. berghei infection was assessed by flow cytometry. Furthermore, the influence of modulating IL-35 on histopathological hallmarks of malaria and disease progression was evaluated.
RESULTS: Interleukin-35 was significantly up regulated in serum and tissues of P. berghei infected mice and correlated with parasitaemia. Neutralization of IL-35 significantly enhanced the release of IFN-γ, decreased the expression of IL-6 and decreased parasitaemia patency. Neutralization of IL-35 was also associated with a tendency towards increased survival as well as the absence of pathological features associated with malaria infection unlike recombinant IL-35 protein administration which sustained a normal course of infection and unfavourable malaria associated histological outcomes in P. berghei infected mice.
CONCLUSION: These results indicate the involvement of IL-35 in P. berghei induced malaria infection. IL-35 neutralization strategies may represent viable therapeutic modalities beneficial for the resolution of malaria infection.
METHODS: The expression of CRP CR1, CD55, CD59, and the phagocytic regulator CD47, on uninfected normocytes and reticulocytes were assessed in individuals from two study populations: (1) P. falciparum and P. vivax-infected patients from a low transmission setting in Sabah, Malaysia; and, (2) malaria-naïve volunteers undergoing P. falciparum induced blood-stage malaria (IBSM). For clinical infections, individuals were categorized into anaemia severity categories based on haemoglobin levels. For IBSM, associations between CRPs and haemoglobin level were investigated.
RESULTS: CRP expression on RBC was lower in Malaysian individuals with P. falciparum and P. vivax mild malarial anaemia compared to healthy controls. CRP expression was also reduced on RBCs from volunteers during IBSM. Reduction occurred on normocytes and reticulocytes. However, there was no significant association between reduced CRPs and haemoglobin during IBSM.
CONCLUSIONS: Removal of CRPs occurs on both RBCs and reticulocytes during Plasmodium infection even in mild malarial anaemia and at low levels of parasitaemia.