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Infectious Diseases of Poverty May 2024Lao PDR has made significant progress in malaria control. The National Strategic Plans outline ambitious targets, aiming for the elimination of Plasmodium falciparum and... (Review)
Review
BACKGROUND
Lao PDR has made significant progress in malaria control. The National Strategic Plans outline ambitious targets, aiming for the elimination of Plasmodium falciparum and P. vivax malaria from all northern provinces by 2025 and national elimination by 2030. This article presents an overview of malaria epidemiology, surveillance, and response systems in Lao PDR, emphasizing experiences and achievements in transmission reduction.
METHODS
Data on surveillance, monitoring and evaluation systems, human resources, infrastructure, and community malaria knowledge during 2010-2020 were systematically gathered from the national program and relevant documents. The collected information was synthesized, and discussions on challenges and future prospects were provided.
RESULTS
Malaria control and elimination activities in Lao PDR were implemented at various levels, with a focus on health facility catchment areas. There has been significant progress in reducing malaria transmission throughout the country. Targeted interventions, such as case management, vector control, and community engagement, using stratification of control interventions by catchment areas have contributed to the decline in malaria cases. In elimination areas, active surveillance strategies, including case and foci investigation, are implemented to identify and stop transmission. The surveillance system has facilitated timely detection and response to malaria cases, enabling these targeted interventions in higher-risk areas.
CONCLUSIONS
The malaria surveillance and response system in Lao PDR has played a crucial role in reducing transmission and advancing the country towards elimination. Challenges such as importation, drug resistance, and sustaining support require ongoing efforts. Further strengthening surveillance, improving access to services, and addressing transmission determinants are key areas of focus to achieve malaria elimination and enhance population health in Lao PDR.
Topics: Laos; Humans; Disease Eradication; Malaria; Epidemiological Monitoring; Malaria, Vivax; Population Surveillance; Malaria, Falciparum
PubMed: 38783374
DOI: 10.1186/s40249-024-01202-7 -
Malaria Journal May 2024Plasmodium vivax represents the most geographically widespread human malaria parasite affecting civilian and military populations in endemic areas. Targeting the...
Evaluation of naturally acquired immune responses against novel pre-erythrocytic Plasmodium vivax proteins in a low endemic malaria population located in the Peruvian Amazon Basin.
BACKGROUND
Plasmodium vivax represents the most geographically widespread human malaria parasite affecting civilian and military populations in endemic areas. Targeting the pre-erythrocytic (PE) stage of the parasite life cycle is especially appealing for developing P. vivax vaccines as it would prevent disease and transmission. Here, naturally acquired immunity to a panel of P. vivax PE antigens was explored, which may facilitate vaccine development and lead to a better understanding of naturally acquired PE immunity.
METHODS
Twelve P. vivax PE antigens orthologous to a panel of P. falciparum antigens previously identified as highly immunogenic in protected subjects after immunization with radiation attenuated sporozoites (RAS) were used for evaluation of humoral and cellular immunity by ELISA and IFN-γ ELISpot. Samples from P. vivax infected individuals (n = 76) from a low endemic malaria region in the Peruvian Amazon Basin were used.
RESULTS
In those clinical samples, all PE antigens evaluated showed positive IgG antibody reactivity with a variable prevalence of 58-99% in recently P. vivax diagnosed patients. The magnitude of the IgG antibody response against PE antigens was lower compared with blood stage antigens MSP1 and DBP-II, although antibody levels persisted better for PE antigens (average decrease of 6% for PE antigens and 43% for MSP1, p < 0.05). Higher IgG antibodies was associated with one or more previous malaria episodes only for blood stage antigens (p < 0.001). High IgG responders across PE and blood stage antigens showed significantly lower parasitaemia compared to low IgG responders (median 1,921 vs 4,663 par/µl, p < 0.05). In a subgroup of volunteers (n = 17),positive IFN-γ T cell response by ELISPOT was observed in 35% vs 9-35% against blood stage MSP1 and PE antigens, respectively, but no correlation with IgG responses.
CONCLUSIONS
These results demonstrate clear humoral and T cell responses against P. vivax PE antigens in individuals naturally infected with P. vivax. These data identify novel attractive PE antigens suitable for use in the potential development and selection of new malaria vaccine candidates which can be used as a part of malaria prevention strategies in civilian and military populations living in P. vivax endemic areas.
Topics: Plasmodium vivax; Peru; Humans; Malaria, Vivax; Adult; Male; Young Adult; Adolescent; Female; Middle Aged; Protozoan Proteins; Antigens, Protozoan; Immunoglobulin G; Antibodies, Protozoan; Enzyme-Linked Immunosorbent Assay; Child; Aged; Enzyme-Linked Immunospot Assay
PubMed: 38783317
DOI: 10.1186/s12936-024-04978-z -
Journal of Parasitology Research 2024Malaria is one of the major public health problems in sub-Saharan Africa, including Ethiopia. Children under the age of five are immunologically naive to plasmodium...
Malaria is one of the major public health problems in sub-Saharan Africa, including Ethiopia. Children under the age of five are immunologically naive to plasmodium parasites, making them the most vulnerable group to clinical manifestations of malaria infection. Despite the severity of the disease in children under five years of age, most studies on malaria focus on the adult population. In the present study, a cross-sectional study design based on health facilities was used during the minor malaria season from February 18 to May 28, 2023, at Mohammed Akile Memorial General Hospital, in Afar Regional State, district of Amibara located in the town of Berta. The finding revealed that 19.8% prevalence among symptomatic children with 61.04% and 38.96% of and , respectively. In the present study area, malaria infection in children under five years of age is significantly associated with the presence of stagnant water in the residential area, inappropriate or no use of insecticide-treated net, and indoor residual spraying (IRS). The prevalence of malaria among symptomatic children under five years of age is higher compared to the national prevalence of malaria among the general population. Therefore, community mobilization through health promotion, aiming to interrupt the transmission of malaria at the community level, is paramount.
PubMed: 38774540
DOI: 10.1155/2024/6365077 -
Journal of Parasitology Research 2024Despite extensive efforts and achievements made in prevention and control, malaria is still a public health problem in Ethiopia. Currently, the case number has been...
BACKGROUND
Despite extensive efforts and achievements made in prevention and control, malaria is still a public health problem in Ethiopia. Currently, the case number has been climbing, even changing the epidemiology to the previously low-burden reporting locations. Therefore, our study is aimed at assessing malaria prevalence and associated risk factors in outpatients, Northwest Ethiopia.
METHODS
A facility-based cross-sectional study was conducted among 318 malaria-suspected outpatients from October 22 to December 15, 2022, at Teda Health Center, Northwest Ethiopia. Sociodemographic characteristics and malaria risk factors were assessed by a face-to-face interview using a pretested questionnaire. parasites were detected by using microscopy on a blood film stained with 10% and 3% Giemsa stain. The data were analyzed using Statistical Package for Social Sciences software version 25, and statistical significance was reported at a value < 0.05.
RESULTS
Of the 318 study participants, 124 (39.0%; 95%CI = 33.6% - 44.6%) tested positive for infection. , , and mixed infections were identified in 71 (57.3%), 47 (37.9%), and 6 (4.8%), respectively, among positive study participants. Individuals above the age of 15 (AOR = 2.704, 95% CI 1.370-5.336) were more likely to be infected with than under-five-year-old individuals. Rural residents (AOR = 2.56, 95% CI 1.281-5.098), those who sleep or work outside at night (AOR = 1.99, 95% CI 1.020-3.875), and individuals who did not use long-lasting insecticide-treated net (AOR = 3.26, 95% CI 1.633-6.499) and had a family member with a history of malaria (AOR = 2.902, 95%CI = 1.671 - 5.041) had higher odds of acquiring infection than their counterparts.
CONCLUSION
In our study area, malaria was a major health problem, with being the dominant species. Multiple environmental and behavioural factors were associated with the infection acquisition. Therefore, urgent holistic intervention is required.
PubMed: 38774539
DOI: 10.1155/2024/8919098 -
Journal of Mathematical Biology May 2024Malaria is a vector-borne disease that exacts a grave toll in the Global South. The epidemiology of Plasmodium vivax, the most geographically expansive agent of human...
Malaria is a vector-borne disease that exacts a grave toll in the Global South. The epidemiology of Plasmodium vivax, the most geographically expansive agent of human malaria, is characterised by the accrual of a reservoir of dormant parasites known as hypnozoites. Relapses, arising from hypnozoite activation events, comprise the majority of the blood-stage infection burden, with implications for the acquisition of immunity and the distribution of superinfection. Here, we construct a novel model for the transmission of P. vivax that concurrently accounts for the accrual of the hypnozoite reservoir, (blood-stage) superinfection and the acquisition of immunity. We begin by using an infinite-server queueing network model to characterise the within-host dynamics as a function of mosquito-to-human transmission intensity, extending our previous model to capture a discretised immunity level. To model transmission-blocking and antidisease immunity, we allow for geometric decay in the respective probabilities of successful human-to-mosquito transmission and symptomatic blood-stage infection as a function of this immunity level. Under a hybrid approximation-whereby probabilistic within-host distributions are cast as expected population-level proportions-we couple host and vector dynamics to recover a deterministic compartmental model in line with Ross-Macdonald theory. We then perform a steady-state analysis for this compartmental model, informed by the (analytic) distributions derived at the within-host level. To characterise transient dynamics, we derive a reduced system of integrodifferential equations, likewise informed by our within-host queueing network, allowing us to recover population-level distributions for various quantities of epidemiological interest. In capturing the interplay between hypnozoite accrual, superinfection and acquired immunity-and providing, to the best of our knowledge, the most complete population-level distributions for a range of epidemiological values-our model provides insights into important, but poorly understood, epidemiological features of P. vivax.
Topics: Humans; Plasmodium vivax; Superinfection; Malaria, Vivax; Animals; Mathematical Concepts; Mosquito Vectors; Disease Reservoirs; Models, Biological; Computer Simulation; Anopheles
PubMed: 38772937
DOI: 10.1007/s00285-024-02088-7 -
PLOS Global Public Health 2024Sensitive and accurate malaria diagnosis is required for case management to accelerate control efforts. Diagnosis is particularly challenging where multiple Plasmodium...
Sensitive and accurate malaria diagnosis is required for case management to accelerate control efforts. Diagnosis is particularly challenging where multiple Plasmodium species are endemic, and where P. falciparum hrp2/3 deletions are frequent. The Noul miLab is a fully automated portable digital microscope that prepares a blood film from a droplet of blood, followed by staining and detection of parasites by an algorithm. Infected red blood cells are displayed on the screen of the instrument. Time-to-result is approximately 20 minutes, with less than two minutes hands-on time. We evaluated the miLab among 659 suspected malaria patients in Gondar, Ethiopia, where P. falciparum and P. vivax are endemic, and the frequency of hrp2/3 deletions is high, and 991 patients in Ghana, where P. falciparum transmission is intense. Across both countries combined, the sensitivity of the miLab for P. falciparum was 94.3% at densities >200 parasites/μL by qPCR, and 83% at densities >20 parasites/μL. The miLab was more sensitive than local microscopy, and comparable to RDT. In Ethiopia, the miLab diagnosed 51/52 (98.1%) of P. falciparum infections with hrp2 deletion at densities >20 parasites/μL. Specificity of the miLab was 94.0%. For P. vivax diagnosis in Ethiopia, the sensitivity of the miLab was 97.0% at densities >200 parasites/μL (RDT: 76.8%, microscopy: 67.0%), 93.9% at densities >20 parasites/μL, and specificity was 97.6%. In Ethiopia, where P. falciparum and P. vivax were frequent, the miLab assigned the wrong species to 15/195 mono-infections at densities >20 parasites/μL by qPCR, and identified only 5/18 mixed-species infections correctly. In conclusion, the miLab was more sensitive than microscopy and thus is a valuable addition to the toolkit for malaria diagnosis, particularly for areas with high frequencies of hrp2/3 deletions.
PubMed: 38768243
DOI: 10.1371/journal.pgph.0003091 -
SAGE Open Medicine 2024In the Eastern Mediterranean region, Afghanistan ranks third for the world's highest burden of malaria. The vast majority (95%) of malaria cases in Afghanistan are...
BACKGROUND
In the Eastern Mediterranean region, Afghanistan ranks third for the world's highest burden of malaria. The vast majority (95%) of malaria cases in Afghanistan are attributed to and 5% to . Most cases occur in low-altitude regions, especially in the eastern province of Nangarhar, where agriculture and farming are predominant. To better understand the public sentiment toward malaria, this study aimed to understand the knowledge, attitude, and practice of patients toward malaria who visited public and private hospitals of Nangarhar province.
METHODS
A cross-sectional descriptive study was conducted on Nangarhar residents who visited the adult Outpatient departments of eight local public and private health facilities. Data collection took place from 1st August 2022 to 15th September 2022.
RESULTS
Of 700 participants, 37.9% ( = 265) identified as male and 62.1% ( = 435) identified as female. The majority of participants (84.6 %) were within the (18-40) age range, followed by 12.7% in the (41-60) age range, and 2.7% were aged 61 years or older. Moreover, 99.7% ( = 698) of the participants had heard of malaria. The main sources of information about malaria were family members (31.3%, = 219), television (32.6%, = 228), Internet (12.6%, = 88), school (11.3%, = 79), and health facilities (31.4%, = 220). Most respondents correctly identified mosquito bites as the primary mode of malaria transmission (72.6%, = 508). Others suggested that transmission could occur by close contact with a malaria patient (14.0%, = 98) and drinking contaminated water (17.3%, = 121). The majority of participants (70.6%) agreed that malaria is a serious and life-threatening disease. A significant number of participants (96.6%) reported owning an insecticide-treated mosquito net at home, and 87.0% reported using the net.
CONCLUSION
Overall, participants reported good knowledge, attitude, and practice toward malaria. This may be linked to the awareness campaigns and preventive programs in Nangarhar province that have contributed to participant's willingness to prevent malaria and treat themselves if they get infected. Public health campaigns are difficult in Afghanistan with weak governance and conflict, and thus, populations may find themselves at risk if health promotion activities are stopped.
PubMed: 38764536
DOI: 10.1177/20503121241251758 -
Communications Medicine May 2024Five years after successful malaria elimination, Aneityum Island in Vanuatu experienced an outbreak of Plasmodium vivax of unknown origin in 2002. Epidemiological...
BACKGROUND
Five years after successful malaria elimination, Aneityum Island in Vanuatu experienced an outbreak of Plasmodium vivax of unknown origin in 2002. Epidemiological investigations revealed several potential sources of P. vivax. We aimed to identify the genetic origin of P. vivax responsible for the resurgence.
METHODS
Five P. vivax microsatellite markers were genotyped using DNA extracted from archived blood samples. A total of 69 samples from four P. vivax populations was included: 29 from the outbreak in 2002, seven from Aneityum in 1999 and 2000, 18 from visitors to Aneityum in 2000, and 15 from nearby Tanna Island in 2002. A neighbour-joining phylogenetic tree was constructed to elucidate the relationships among P. vivax isolates. STRUCTURE and principal component analysis were used to assess patterns of genetic structure.
RESULTS
Here we show distinct genetic origins of P. vivax during the outbreak on Aneityum. While the origin of most P. vivax lineages found during the outbreak remains unidentified, limited genetic diversity among these lineages is consistent with a rapid expansion from a recent common ancestor. Contemporaneous P. vivax from neighboring Tanna and potential relapse of P. vivax acquired from other islands in 1999 and 2000 are also identified as minor contributors to the outbreak.
CONCLUSIONS
Multiple reintroductions of P. vivax after elimination highlight the high receptivity and vulnerability to malaria resurgence in island settings of Vanuatu, despite robust surveillance and high community compliance to control measures.
PubMed: 38762604
DOI: 10.1038/s43856-024-00524-9 -
Infection, Genetics and Evolution :... Aug 2024Plasmodium vivax Merozoite Surface Protein 8 (PvMSP8) is a promising candidate target for the development of multi-component vaccines. Therefore, determining the genetic...
Plasmodium vivax Merozoite Surface Protein 8 (PvMSP8) is a promising candidate target for the development of multi-component vaccines. Therefore, determining the genetic variation pattern of Pvmsp8 is essential in providing a reference for the rational design of the P. vivax malaria vaccines. This study delves into the genetic characteristics of the Pvmsp8 gene, specifically focusing on samples from the China-Myanmar border (CMB) region, and contrasts these findings with broader global patterns. The study uncovers that Pvmsp8 exhibits a notable level of conservation across different populations, with limited polymorphisms and relatively low nucleotide diversity (0.00023-0.00120). This conservation contrasts starkly with the high polymorphisms found in other P. vivax antigens such as Pvmsp1. A total of 25 haplotypes and 14 amino acid mutation sites were identified in the global populations, and all mutation sites were confined to non-functional regions. The study also notes that most CMB Pvmsp8 haplotypes are shared among Burmese, Cambodian, Thai, and Vietnamese populations, indicating less geographical variance, but differ notably from those found in Pacific island regions or the Panama. The findings underscore the importance of considering regional genetic diversity in P. vivax when developing targeted malaria vaccines. Non departure from neutral evolution were found by Tajima's D test, however, statistically significant differences were observed between the kn/ks rates. The study's findings are crucial in understanding the evolution and population structure of the Pvmsp8 gene, particularly during regional malaria elimination efforts. The highly conserved nature of Pvmsp8, combined with the lack of mutations in its functional domain, presents it as a promising candidate for developing a broad and effective P. vivax vaccine. This research thus lays a foundation for the rational development of multivalent malaria vaccines targeting this genetically stable antigen.
Topics: Plasmodium vivax; Selection, Genetic; Protozoan Proteins; Haplotypes; Humans; Genetic Variation; Malaria, Vivax; Mutation; Phylogeny; Antigens, Protozoan
PubMed: 38759940
DOI: 10.1016/j.meegid.2024.105605 -
Malaria Journal May 2024Malaria is a major public health concern in Ethiopia, where more than half of the population lives in malaria risk areas. While several studies have been conducted in...
BACKGROUND
Malaria is a major public health concern in Ethiopia, where more than half of the population lives in malaria risk areas. While several studies have been conducted in different eco-epidemiological settings in Ethiopia, there is a notable scarcity of data on the prevalence of malaria in the Gindabarat district. Therefore, this study aimed to analyse 10-year trend of malaria prevalence in Gindabarat district, West Shawa Zone of Oromia, Western Ethiopia.
METHODS
A retrospective laboratory record review was conducted at Gindabarat General Hospital and Gindabarat District Health Office from September 2011 to August 2020. The retrieved data included the date of examination, age, sex and laboratory results of the blood smears, including the Plasmodium species identified. Data were summarized and presented in the form of tables, figures, and frequencies to present the results. The data were analysed using SPSS (version 25.0) and Microsoft Excel.
RESULTS
Over the course of 10 years, a total of 11,478 blood smears were examined in the public health facilities in the district. Of the total blood smears examined, 1372 (11.95%) were microscopically confirmed malaria. Plasmodium falciparum, Plasmodium vivax and mixed infections (P. falciparum and P. vivax) accounted for 70.77%, 20.55% and 8.67% of the cases, respectively. Malaria prevalence was significantly higher among individuals aged ≥ 15 years (12.60%, x = 13.6, df = 2, p = 0.001) and males (14.21%, x = 59.7, df = 1, p = 0.001). The highest number of malaria cases was recorded from September to November.
CONCLUSION
Malaria remains a public health problem in the district. P. falciparum was the most predominant parasite species in the area. Malaria prevalence was significantly higher among individuals aged ≥ 15 years and males. There was a remarkable fluctuation in the number of malaria cases in different months and years. In the study area malaria cases peaked in 2015 and 2017 then decreasing from 2017 to 2019, with sharp increase in 2020. Moreover, this study showed malaria cases were reported in all seasons and months, but the highest was observed from September to November. Strengthening malaria control activities is essential to further reduce the burden of malaria and pave the way for the anticipated elimination.
Topics: Ethiopia; Prevalence; Male; Humans; Female; Retrospective Studies; Adolescent; Adult; Young Adult; Child; Child, Preschool; Malaria, Vivax; Middle Aged; Infant; Malaria, Falciparum; Plasmodium vivax; Plasmodium falciparum; Aged; Infant, Newborn; Aged, 80 and over
PubMed: 38755638
DOI: 10.1186/s12936-024-04975-2