Malaria Journal最新文献

Background: Larval source management (LSM) is re-emerging as a critical malaria intervention to address challenges associated with core vector control tools, such as insecticide-treated nets (ITNs), and to accelerate progress towards elimination. Presently, LSM is not widely used in rural settings and is instead more commonly applied in urban and arid settings. A systematic entomological assessment was conducted in rural communities of southeastern Tanzania, where insecticide-treated nets (ITNs) are widely used, to explore opportunities for deploying LSM to improve malaria control.

Methods: Aquatic habitat surveys were conducted in 2022 and 2023 to understand habitat usage by different mosquito vectors, covering five villages during the rainy season and seven villages during the dry season. Additionally, samples of adult mosquitoes were collected to assess the role of various Anopheles species in malaria transmission in the area, and to explore opportunities for species sanitation using targeted LSM.

Results: Adult mosquito surveys showed that in this area, the total entomological inoculation rates (EIR) for indoor collections were 20.1 and 6.5 infectious bites per person per year for outdoors. Anopheles funestus and Anopheles arabiensis were the only Anopheles vectors identified. Anopheles funestus was responsible for over 97.6% of the malaria transmission indoors and 95.4% outdoors. The concurrent larval surveys found that habitats with late instar An. arabiensis and An. funestus comprised only a small subset of 11.2%-16.5% of all water bodies in the rainy season, and 9.7%-15.2% in the dry season. In terms of size, these habitats covered 66.4%-68.2% of the total habitat areas in the wet season, reducing to 33.9%-40.6% in the dry season. From the rainy season to the dry season, the surface area of habitats occupied by An. arabiensis and An. funestus decreased by 92.0% to 97.5%, while the number of habitats occupied by An. arabiensis and An. funestus decreased by 38.0% to 57.3%. Anopheles funestus preferred large, permanent habitats with clear water and vegetation year-round, while An. arabiensis showed contrasting seasonal preferences, favouring sunlit still waters in the rainy season and larger, opaque habitats in the dry season.

Conclusion: These findings suggest that An. funestus, which is the dominant malaria vector in the area, mediating over 95% of malaria transmission, preferentially occupies only a small subset of uniquely identifiable aquatic habitats in both wet and dry seasons. This presents an opportunity to expand LSM in rural settings by carefully targeting An. funestus habitats, which might be effective and logistically feasible as a complementary approach alongside existing interventions. Further research should assess the impact of targeted LSM for species sanitation compared to blanket LSM.

Background: Attractive targeted sugar bait (ATSB) stations containing bait (to attract) and ingestion toxicant (to kill) sugar-foraging mosquitoes are hypothesized to reduce malaria transmission by shortening the lifespan of Anopheles vectors.

Methods: A two-arm cluster-randomized controlled trial (cRCT) was conducted in Western Province Zambia. Seventy clusters of 250-350 households were assigned (1:1) by restricted randomization to an intervention arm (ATSB) or control arm (no ATSB) in the context of standard of care vector control (insecticide-treated nets and/or indoor residual spraying). Two ATSB stations (Westham Sarabi, 0.11% dinotefuran w/w) were maintained on exterior walls of eligible household structures for a 7-month deployment period (December-June) during the high malaria transmission season. The primary outcome was clinical malaria incidence among two consecutive seasonal cohorts of children aged 1-14 years, followed-up monthly from January-June in 2022 and 2023. Secondary outcome was Plasmodium falciparum prevalence among individuals aged over six months. Analysis compared clinical malaria incidence and prevalence between arms among the intention-to-treat population.

Results: ATSB coverage, assessed by cross-sectional survey, was 98.3% in March-April 2022 and 89.5% in March-April 2023. 4494 children contributed any follow-up time to the cohort, with 2313 incident malaria cases in the intervention arm (1.28 per child per six-month transmission season), and 2449 in the control arm (1.38 per child-season). The incidence rate ratio between the two arms was 0.91 (95% CI 0.72-1.15, p = 0.42). 2536 individuals participated in cross-sectional surveys, with prevalence of P. falciparum 50.7% in the intervention arm and 53.5% in the control arm. The odds ratio between the two arms was 0.89 (95% CI 0.66-1.18, p = 0.42). Secondary covariable-adjusted and subgroup analyses did not substantially alter the findings. No serious adverse events associated with the intervention were reported.

Conclusions: Two ATSB stations deployed per eligible structure for two consecutive transmission seasons did not result in a statistically significant reduction in clinical malaria incidence among children aged 1-14 years or in P. falciparum prevalence in rural western Zambia. Further studies are needed to assess the efficacy of ATSB stations in different settings and with different deployment strategies.

Trial registration: The trial is registered with Clinicaltrials.gov (NCT04800055).

Background: Recent reports from Thailand reveal a substantial surge in Plasmodium knowlesi cases over the past decades, with a more than eightfold increase in incidence by 2023 compared to 2018. This study investigates temporal changes in genetic polymorphism associated with the escalating transmission of P. knowlesi malaria in Thailand over time using the prominent vaccine candidate, pkmsp1 as a marker.

Methods: Twenty-five P. knowlesi samples collected in 2018-2023 were sequenced for the 42-kDa region of pkmsp1 and compared with 24 retrieved sequences in 2000-2009, focusing on nucleotide diversity, natural selection, recombination rate, and population differentiation.

Results: Seven unique haplotypes were identified in recent samples, compared to 15 in earlier samples. Nucleotide and haplotype diversity were lower in recent samples (π = 0.016, Hd = 0.817) than in earlier samples (π = 0.018, Hd = 0.942). Significantly higher synonymous substitution rates were observed in both sample sets (d_S-d_N = 2.77 and 2.43, p < 0.05), indicating purifying selection and reduced genetic diversity over time. Additionally, 8 out of 17 mutation points were located on predicted B-cell epitopes, suggesting an adaptive response by the parasites to evade immune recognition. Population differentiation analysis using the fixation index (F_st) revealed high genetic differentiation between parasite populations in central and southern Thailand or Malaysia. Conversely, the relatively lower F_st value between southern Thailand and Malaysia suggests a closer genetic relationship, possibly reflecting historical gene flow.

Conclusion: This study highlights a decline in genetic diversity and evidence of purifying selection associated with the recently increased incidence of P. knowlesi malaria in Thailand. The minor genetic differentiation between P. knowlesi populations from southern Thailand and Malaysia suggests a shared recent ancestry of these parasites and underscores the need for coordinated efforts between the two countries for the elimination of P. knowlesi.

Background: In 2020, Malawi had 6.9 million malaria cases and 2551 deaths, mainly in children under five years of age. The 2017-2022 Malawi malaria control strategic plan promoted the consistent use of insecticide-treated nets through free distribution and mass campaigns. Despite widespread availability of the control strategy plan, Chikwawa District continues to suffer from high malaria burden especially among under five children, due to inconsistent insecticide-treated (ITN) net usage. For this reason, this study aimed at exploring caregivers' perceptions on insecticide-treated net utilisation and also find out about its effectiveness among those who consistently use them.

Methods: This study used a sequential exploratory mixed methods design. The data used for quantitative analysis was drawn from the population of under-five children's caregivers within the catchment area of Chikwawa district hospital. The sample size was 96 participants, as determined by Cochran's formula. The data collection lasted from December 2023 to April 2024 and included four in-depth interviews and three focus group discussions to address the objectives qualitatively.

Results: The study revealed that 91.67% of households used ITNs, with 87.50% using them daily. The significant factors influencing ITN utilisation included the number of nets, user satisfaction, perceived impact, user habits, acquisition method, and usage frequency (all p values < 0.001). Under-five malaria cases were also significant (p = 0.025). The odds of the perceived net impact influencing utilisation were 4.956 times greater. Non-usage was due to heat, quality concerns, limited access, breathing difficulties, health conditions such as asthma, and misconceptions about net treatment.

Conclusion: The study revealed a strong belief in insecticide-treated net efficacy. However, some challenges such as access, durability, and misinformation of insecticide-treated nets were discovered. These challenges affected utilisation of insecticide-treated nets in agreement with some literature reviewed. The insights found in this study will help policymakers in addressing health interventions for the reduction of malaria cases in Malawi.

Background: Essential oils of Cymbopogon citratus and Hyptis suaveolens are known for their insecticidal properties, but remain ineffective against mosquitoes resistant to synthetic insecticides. In order to improve insecticidal properties of these plants, this study aimed to investigate the chemical composition and insecticidal activity against Anopheles gambiae mosquitoes of essential oil obtained by co-distillation of dry leaves of C. citratus and H. suaveolens.

Methods: Essential oils were extracted by hydrodistillation from dry leaves of C. citratus and H. suaveolens, separately, then from the mixture of the dry leaves of the two plants in mass ratio 50/50. Each pure essential oil and the mixture obtained either by co-distillation or by combining pure essential oils in volume ratio 50/50 were then analysed by GC/MS. All essential oils and Deltamethrin 0.05% (positive control) were tested on two species of mosquitoes of the genus Anopheles gambiae according to the World Health Organization standard methods.

Results: Essential oil obtained by co-distillation mainly contained piperitone (40.80%), 1,8-cineole (24.64%), p-menth-4(8)-ene (13.20%), limonene (6.09%) and α-pinene (4.73%). However, the mixture of pure essential oils of these two plants mostly contained geranial (20.74%), neral (16.42%), 1,8-cineole (19.79%), sabinene (6.03%) and β-pinene (3.87%). The essential oil of C. citratus mainly contained geranial (41.49%), neral (32.83%), β-myrcene (13.66%) and geraniol (3.49%) while the major constituents of essential oil of H. suaveolens were 1,8-cineole (39.58%), sabinene (12.06%), β-pinene (7.73%), α-terpinolene (6.72%) and (E)-caryophyllene (7.49%). At the dose of 1%, all essential oils, except that of H. suaveolens, induced about 100% of mortality on the sensitive species of An. gambiae. However, on the resistant species at the same dose, the essential oil obtained by co-distillation induced the highest mortality (53.44%). The essential oils of C. citratus, H. suaveolens and the mixture of the two pure essential oils caused respectively 2.47, 15.28 and 18.33% of mortality. The synthetic insecticide caused 100 and 14.84% of mortality respectively on the sensitive and resistant species of An. gambiae.

Conclusion: Essential oil obtained by co-distillation showed good insecticidal efficacy against a resistant species of An. gambiae and might constitute a new solution to fight against mosquitoes resistant to synthetic insecticides.

Background: Malaria remains a significant concern for children under five in malaria-endemic regions. Rwanda's successful efforts in malaria treatment reduced nationwide cases, but high mortality persists in the Eastern and Southern provinces. This study aimed to investigate the clinical features of severe malaria and to identify the death risk factors among under-five children in Eastern province Hospitals.

Methods: This cross-sectional study assessed severe malaria-related mortality and associated factors among children aged under five years in hospitals of Eastern Province, Rwanda, from 2017 to 2021. Data were collected from hospital records, and descriptive statistics and logistic regression were used for data analysis.

Results: Factors associated with severe malaria-related mortality included coma (aOR: 10, 95% CI: 1.2-82.5, p = 0.03), Vomiting (aOR: 5.2, 95% CI: 1.0-26.0, p = 0.04), four or more days of illness before consultation (aOR: 30.9, 95% CI: 8.7-109.9, p < 0.01). On the other hand, a low parasitaemia level (aOR: 0.01, 95% CI: 0.0-0.1, p < 0.01).

Conclusion: In conclusion, coma, vomiting, and healthcare delays increased mortality in children with severe malaria. Prompt treatment, proper assessments, protocol adherence, and caregiver education on early symptom recognition are crucial for improving outcomes.

Background: Malaria remains a significant public health burden, necessitating evidence-based strategies to reduce prevalence and associated morbidity. This study explores the potential of integrated healthcare, encompassing both modern and traditional herbal medicine (THM), for malaria control in Ghana.

Methods: Employing a qualitative approach, semi-structured interviews were conducted with medical doctors, pharmacists, and THM providers. Thematic analysis approach was utilized to inductively analyse interview data and integrate participants' lived experiences and suggestions.

Results: Six themes emerged: Standardization of THM practice; Training on THM broadened; Research on THM expanded; Increasing awareness of THM integration hospitals and inclusion of THM in national health insurance scheme; Constant supply of certified herbal medications; and Tax relief provision. These recommendations form the 'STRICT' framework for developing functional health system for promoting an effective malaria control through integrated healthcare in Ghana.

Conclusion: It was evident that the 'STRICT' framework can potentially transform healthcare delivery and improve service quality for malaria patients. Policymakers, healthcare providers, and managers can utilize these insights to advocate for and implement integrated healthcare strategies, ultimately enhancing service delivery for all Ghanaians, particularly those suffering from malaria.

Background: Borneo, the third largest island in the world, is facing a significant burden of emerging and re-emerging vector-borne diseases due to rapid changes in primary tropical rainforests and urban landscapes. These vector-borne diseases include the endemic epidemic cycles that occur in the more populated and urbanized areas, as well as the possible transmission through enzootic and sylvatic transmission cycles that occur mainly in the overlapping landscapes or among the indigenous population in the forest. The island will be changed significantly in the future due to the increase in human activities, especially mega events such as the relocation of the Indonesian capital to Nusantara in East Kalimantan Borneo, increasing urbanization, agriculture, hydropower projects, ecotourism activities in Sabah, North Borneo, and Sarawak, Central and South Borneo. Therefore, an overview of the current situation of vector-borne diseases is crucial for the next possible epidemic preparedness.

Methods: This study conducted the PRISMA-ScR scoping review and formulated a set of research questions to identify current trends in vector-borne diseases in Borneo. These questions aim to identify which diseases have been studied, what geographical areas have been covered by the research, how the One Health approach-encompassing human, animal and environmental factors-is integrated, and what gaps and challenges exist in addressing these diseases.

Results: A total of 2241 references were screened for eligibility and 117 articles were selected for review. The majority of the materials focused on mosquitoes and malaria, and the One Health elements focused mainly on humans.

Conclusions: This review has identified the most and least studied vector-borne diseases and highlighted some of the gaps in knowledge and research on vector-borne diseases on the island of Borneo. Future studies should particularly focus on other neglected diseases such as Zika, chikungunya, Japanese encephalitis, filariasis and tick-borne diseases. In addition, advanced surveillance systems will be developed to improve early detection and response specifically for remote regions where vector-borne diseases are endemic or emerging.

Background: Malaria continues to be a significant global health concern, and developing effective therapeutic strategies requires an understanding of the immune response to the disease. This systematic review synthesized the current body of research on the role of regulated on activation, normal T cell expressed and secreted (RANTES)-in the pathogenesis and disease severity of malaria.

Methods: A systematic review protocol was registered with PROSPERO under the registration number CRD42024535822. The systematic review was conducted following PRISMA guidelines to identify studies examining RANTES levels in individuals infected with Plasmodium species. Searches were performed across multiple databases, including ProQuest, Journals@Ovid, Embase, Scopus, PubMed, and MEDLINE. Further searches were performed in Google Scholar. Quality assessment was done using the Joanna Briggs Institute (JBI) critical appraisal tools. Alterations in RANTES levels in patients with malaria were synthesized narratively.

Results: A comprehensive search of major databases identified 22 studies meeting inclusion criteria, predominantly focusing on Plasmodium falciparum and Plasmodium vivax infections. RANTES levels were found to vary significantly across different severities of malaria, with several studies reporting lower levels in severe cases compared to non-malarial controls. However, inconsistencies were observed in the alterations of RANTES levels between severe and non-severe malaria cases.

Conclusion: Taken together, the finding of this systematic review underscore the complex regulation of RANTES in malaria pathophysiology. Future research should focus on longitudinal assessments to elucidate the dynamic role of RANTES throughout the course of malaria and recovery, to potentially inform the design of novel therapeutic strategies.

Background: Malaria is a major cause of ill health and death in children in Africa. The disease also imposes a severe social and economic burden on households and health systems and is strongly associated with poverty. This study summarizes the most up-to-date cost of treating severe malaria in children in Africa.

Methods: A systematic search was conducted in PubMed, Embase, Cinahl, and Web of Science databases. Google and Google Scholar were searched for grey literature followed by scanning of the reference lists of the previous systematic reviews. The search was limited to children < 12 years, malaria-endemic countries in Africa, and the English language. All costs were adjusted to the year 2023.

Results: 19 studies conducted in 12 countries were identified: 14 reported provider costs, and 11 household costs. Out of the 19 studies found, 11 were published before 2018 while 11 reported data that are currently more than ten years old. Studies varied methodologically and in the scope of resources included to estimate the cost. The provider costs ranged from USD 27 in Uganda to USD 165 per patient in Kenya (median value USD 90), while household costs ranged from USD 13 in Kenya to USD 245 per patient in Gabon (median value USD 50). All identified household malaria treatment costs except one represented catastrophic health expenditure, making out more than 10% of the monthly Gross National Income per capita in the respective countries.

Conclusion: Evidence on the cost of treating severe malaria in children in Africa is scarce. However, the few existing studies show that severe malaria in children imposes a significant economic burden on the providers and households. More studies are needed, particularly in high-burden high-impact countries, to inform resource allocation decisions.