Tropical Medicine and Health最新文献

Background: Nigeria accounts for the greatest burden of malaria disease globally. Malaria control requires an effective treatment after diagnosis. The efficacy of antimalarial drugs can be assessed through the analysis of genetic changes associated with reduced drug sensitivity.

Methods: This study includes the analysis of the markers associated with artemisinin (pfk13), sulfadoxine-pyrimethamine (pfdhfr and pfdhps), and chloroquine and its derivatives (pfmdr1 and pfcrt) resistances, in blood samples collected from asymptomatic children in south-western Nigeria.

Results: The 25.95% of samples showed a number of mutations in pfk13 gene. Among those, the validated, C580Y, and the candidate, R515K, mutations by WHO were detected. Twenty-seven pfdhps different haplotypes were observed, with the haplotype ISGKAA as the most prevalent (18.80%), followed by IFGKAA (12.78%) and IAGKAA (11.28%). The VAGKGS was the most common haplotype carrying the I431V mutation (10.53%). Combinations of alleles in pfdhfr and pfdhps genes provided a 40.98% of samples with the partially resistant haplotype (IRNG). No samples exhibited the 'fully resistant' or 'super resistant' pfdhprf-pfdhps combinations, but one sample contained mutations at pfdhfr 51I, 59R, and 108N with pfdhps 431V, 436A, A437G and 540E. The analysis of pfcrt 72-76 variants disclosed a 12.12% of samples with the mutant-type (CVIET). No double mutant pfmdr1 haplotypes 86Y/1246Y (YY) were detected, nor was the haplotype formed by the alleles 86Y pfmdr1 + pfcrt 76 T (YT).

Conclusions: There was no evidence of parasite genomes harbouring multilocus mutations conferring multidrug resistance, although evidence of a validated (C580Y) and a candidate (R515K) mutation in pfk13 gene, high frequency pfdhfr mutant alleles and high variability of pfdhps haplotypes were found in this study, which provides a baseline information essential in monitoring P. falciparum resistances.

Background: Malaria is one of the most infectious life-threatening vector-borne diseases affected by climate change. Because of the emerging climate change problem, it was thought prudent to identify prevalent mosquito species and find the malaria parasite's presence in field-collected mosquitoes in Odisha.

Material and methods: The study was undertaken at four villages in the Rourkela, Sundergarh district of Odisha, India, from January 2018 to January 2020, generating entomological and climatic data. Field-collected mosquitoes were processed, and DNA was extracted, followed by multiplex PCR for differentiation of sibling species for Anopheles culicifacies and Anopheles fluviatilis mosquitoes. Enzyme-Linked immunosorbent assay was also performed for detection of circumsporozoite proteins of Plasmodium. Sequencing was performed, and a phylogenetic tree was constructed using the neighbor-joining method.

Results: For Anopheles culicifacies, 43.25% of mosquitoes belonged to sibling species C, followed by species B, A, and D. Similarly, for Anopheles fluviatilis, sibling species T was found in 57.5%, followed by species U and S. Sibling species were confirmed on the difference in the sequences of conserved regions of the 28S rDNA.

Conclusions: We can conclude that sibling species C (Anopheles culicifacies) was predominant in Rourkela, and sequencing further confirmed the presence of parasites (Plasmodium vivax) in Anopheles culicifacies as sibling species C.

Mpox has re-emerged as a significant public health threat, particularly in Africa. This study explores the key drivers behind the recent resurgence, focusing on epidemiological trends, transmission dynamics, and lessons learned from recent outbreaks. The research involved a comprehensive review of recent mpox outbreaks, analyzing factors, such as socio-economic conditions, environmental influences, and genetic evolution. Findings indicate that the resurgence is linked to the cessation of smallpox vaccination, increased human-wildlife interactions, and rapid urbanization in endemic regions. The virus, which was previously confined to rural areas, has now spread to urban populations, and crossed national borders, driven by high population mobility and socio-economic instability. A notable shift in transmission dynamics has been observed, with increased human-to-human transmission, particularly among men who have sex with men (MSM), contributing to more severe and widespread outbreaks. The study highlights the urgent need to strengthen health systems in Africa, particularly in the areas of diagnostics, surveillance, and public health preparedness. Challenges such as inadequate laboratory infrastructure and delayed response mechanisms have exposed vulnerabilities in current public health frameworks. To prevent future outbreaks, targeted strategies must be implemented, including enhanced community engagement, improved access to vaccines and treatments, and timely, accurate reporting of cases. Coordinated global action is essential to prevent mpox from becoming a more persistent and widespread public health threat. This research discusses the importance of proactive measures and international cooperation in addressing the ongoing threat posed by mpox, particularly in regions with limited healthcare resources.

Background: Dengue fever remains a significant public health challenge in Bangladesh. This study aimed to characterize the clinical and epidemiological profiles of confirmed dengue cases during the 2024 outbreak in Bangladesh.

Methods: This observational study was conducted from June to September 2024 in four tertiary care hospitals across Bangladesh located in four administrative divisions. A total of 401 laboratory-confirmed (NS1- or IgM-positive) dengue patients aged ≥ 12 years were included. Demographic data, clinical presentations, and laboratory findings were collected through face‒to-face interviews. The revised WHO 2009 dengue case classification was used for severity assessment of dengue patients. Descriptive and inferential statistics were used to summarize the results.

Results: The mean age of patients with dengue fever was 29.81 ± 11.64 (SD) years, with 7.2% of the patients being adolescents (aged 12-17 years). A clear male predominance (88.3%) was observed. Overall, 65.6% of patients had dengue with warning signs, and 9% had severe dengue. Fever (94.3%), headache (70.3%), myalgia (66.1%), and gastrointestinal symptoms such as nausea (49.9%) and abdominal pain (43.9%) were common symptoms. The median in-hospital stay of both non-severe and severe cases were 4 & 5 days, respectively. The in-hospital mortality rate was 0.75%, which was significantly higher among severe dengue patients (5.6%).

Conclusion: The 2024 dengue outbreak in Bangladesh predominantly affected young adult males, with a notable prevalence of gastrointestinal symptoms alongside classic dengue manifestations.

Background: Schistosomiasis control relies primarily on mass drug administration with praziquantel. However, persistent reinfection and high treatment costs remain significant challenges. Current strategies largely overlook intermediate host molluscs and infected larvae, which are critical sources of transmission. Niclosamide, the only widely used molluscicide, is limited by its high environmental toxicity and cost, creating a need for safer and more sustainable alternatives.

Methods: In this study, we investigated the effects of a spirulina-based feed derived from the cyanobacterium Arthrospira platensis on infected snails. Laboratory experiments were conducted to assess the impact of spirulina on cercariae release from infected snails. We further examined the safety profile of spirulina by testing its effects on both snails and Japanese medaka. Additionally, the direct effects of spirulina constituents on cercariae viability were evaluated.

Results: Snails fed spirulina presented a significant reduction in cercariae output, with reductions of up to 88%. The reduction was concentration dependent and more pronounced during the early stages of infection. Spirulina had no toxic effects on either snails or Japanese medakas. Further analysis revealed that the active ingredient causing the increase in mortality in cercaria was linoleic acid, a common ingredient in both the spirulina feed and the base feed, and a direct anti-parasitic effect of linoleic acid was confirmed.

Conclusion: Spirulina represents a promising, environmentally safe feed that can reduce the transmission of schistosomiasis by directly impacting schistosome larvae within infected snails and reducing the release of cercariae. This novel approach offers a sustainable and nontoxic alternative to current molluscicidal strategies and may contribute to more effective and environmentally friendly schistosomiasis control.

Background: Bithynia spp., a key intermediate host of Opisthorchis viverrini, is widely distributed in the lower Mekong sub-region, where opisthorchiasis remains a major public health concern. Understanding the genetic diversity and population structure of these snails is crucial for disease control. Bithynia siamensis sensu lato has been classified into three genetic lineages (I-III) based on cytochrome c oxidase subunit 1 (cox1) and 16S ribosomal RNA (16S rRNA) sequence analysis. This study focuses on Champasak Province, Laos, a highly endemic area of opisthorchiasis with limited genetic data on Bithynia spp.

Methods: Bithynia snails were collected from 12 villages in Khong and Mounlapamok districts, Champasak Province, Laos, between February and August 2024. To compare with previous reports, a total of 246 and 139 samples were analyzed using cox1 and 16S rRNA markers, respectively. Genetic diversity, genetic differentiation, and genetic structure were assessed based on these markers. Haplotype networks were constructed based on cox1 and 16S RNA sequences to elucidate the genetic lineage of these samples.

Results: In the present study, only Bithynia siamensis goniomphalos was identified, while B. s. siamensis and B. funiculata were not found. Our findings revealed that both cox1 and 16S rRNA sequences exhibited high haplotype diversity among populations but relatively low nucleotide diversity. Two lineages of B. s. goniomphalos (lineages II and III) were detected in the studied areas, exhibiting significant genetic structuring among groups of snail populations from different villages in each lineage. Notably, lineage II was identified in Laos for the first time. The distribution of lineage II was observed near the southern border of Laos and Cambodia.

Conclusions: This study is the first to use DNA analysis to investigate Bithynia spp. in opisthorchiasis-endemic areas of Champasak Province, where B. s. goniomphalos lineages II and III were detected, but lineage I was not found. Our finding suggested that geographic or environmental factors influence the distribution of specific Bithynia lineages in this region. Many O. viverrini endemic areas in Southeast Asia still lack genetic data on Bithynia snails which could provide valuable insights into the transmission dynamics of opisthorchiasis. Therefore, further investigations should be conducted in these areas using cox1 and 16S rRNA sequences for comparison with previous studies.

Background: Cholera outbreaks have plagued Zambia for decades, with Lusaka district, the capital, being particularly vulnerable. Although the lack of sanitary toilet facilities and inadequate drainage systems were shown to be associated with the high cholera incidence in the early 2000s, it is unknown whether these environmental risk factors persisted in the outbreak that occurred in 2023-2024, which turned out to be the largest outbreak in the country's history. We investigated the geospatial patterns of cholera cases and associated environmental factors during the October 2023 to March 2024 cholera outbreak.

Methods: We conducted a geospatial analysis of the suspected cholera cases in Lusaka district, comprising seven constituencies and 94 townships. Patient information and geocoordinates were collected from suspected cases using electronic surveillance tools. The space-time scan statistics was performed to detect spatial and temporal clusters of cases. Spearman's rank correlation coefficient, were employed to examine the relationship between cholera incidence and various environmental factors, including access to Water, Sanitation, and Hygiene (WASH) facilities and equipment.

Results: Over the study period, 4,591 suspected cholera cases with geocoordinate data were identified, with incidence rates varying across the constituencies. Median cholera incidence (IQR) was 0.55 (0.27-1.44) in Lusaka, with higher incidence rates observed in unplanned residential areas. After the first case identification in Kanyama, cases and clusters were observed in different parts of Lusaka. Among 94 townships in Lusaka, cholera-suspected cases were identified in 86 of them. Among environmental factors analyzed for associations with the high cholera incidence, the proportion of individuals without soap and detergent at home (ρ = 0.457, p < 0.001) and those without water for hand washing at home (ρ = 0.421, p < 0.001) were significantly associated with increased cholera incidence.

Conclusion: The findings underscore the significance of environmental factors in cholera transmission, particularly in unplanned residential areas with inadequate access to WASH facilities which persist in the area. Improving WASH infrastructure and implementing tailored public health strategies, particularly for high-risk areas (e.g., unplanned residential areas), are crucial for mitigating cholera outbreaks in Lusaka District.

Background: Hypertension in pregnancy serves to screen for adverse perinatal outcomes. In 2017, the American College of Cardiology and American Heart Association recommended a new blood pressure category with lower hypertension thresholds, excluding pregnancy. This study aimed to explore the association between the 2017 redefined blood pressure categories in pregnancy and neonatal outcomes such as preterm birth and low birth weight.

Methods: This retrospective study used electronic records of the Maternal and Child Health Handbook registered by the Women and Infant Registration System. All women who had at least one antenatal care visit and delivery between January 2017 and April 2020 and between May and December 2022 were included in the study. A birth of less than 37 weeks was defined as preterm delivery. LBW was identified based on a newborn's birthweight of less than 2500 g. The maximum blood pressure across all antenatal care visits was classified based on the newly recommended criteria. A generalized linear model with binomial distribution and logit link function was used to evaluate the association between new blood pressure categories and neonatal outcomes at different levels of health facilities.

Results: We analyzed data from 825 women. Of these, the prevalence was 13.7% for elevated blood pressure, 15.2% for stage 1 hypertension, 4.5% for non-severe stage 2 hypertension and 1.2% for severe stage 2 hypertension. For lower-level facilities, no significant associations were identified between the redefined blood pressure category and preterm birth or low birthweight. At higher-level facilities, preterm birth was only significantly associated with severe stage 2 hypertension (adjusted odds ratio:10.94; 95% confidence interval:1.08-110.93; P = 0.04) and low birthweight showed no association with the redefined category.

Conclusion: This study revealed no association between redefined lower blood pressure threshold and preterm birth and low birthweight in under-resourced settings. However, previous studies in well-resourced countries with larger sample sizes also reported a significant association. Therefore, further investigations are required.

Background: The genus Chilomastix, including C. mesnili, consists of protozoa that parasitize the gastrointestinal tracts of various host organisms, including mammals (humans and non-human primates [NHP]), birds, and amphibians. Despite its widespread presence, Chilomastix spp. are generally considered non-pathogenic, which has led to limited molecular epidemiological studies on this genus. Consequently, genetic reference data for this genus remain scarce in GenBank. In this study, we aimed to establish a molecular classification for Chilomastix spp. by investigating the genetic diversity of isolates from humans and animals in a parasite-endemic region of Indonesia.

Methods: A cross-sectional molecular investigation was conducted in Wainyapu Village, Sumba Island, Indonesia. Stool samples were collected annually from 2013 to 2016 and screened using polymerase chain reaction (PCR) targeting the 18S small subunit ribosomal RNA gene (18S rRNA) of Chilomastix spp., followed by direct and subcloning sequencing. Genetic haplotypes of the partial 18S rRNA sequence (1386-1953 bp) from humans (n = 25), dogs (n = 1), pigs (n = 23), rats (n = 38), water buffaloes (n = 3), chickens (n = 10), and ducks (n = 1) were analyzed alongside reference sequences from humans, guinea pigs, leeches, frogs, and water sources using phylogenetic analyses.

Results: The prevalence of Chilomastix spp. was 7.0% (25/356) in humans and 19.7% (75/380) in animals. Phylogenetic analyses revealed the following monophyletic clusters as subtypes (STs): C. mesnili ST1 (human-NHP genotype), C. mesnili ST2-1 (human genotype), and C. mesnili ST2-2 (pig genotype). In addition, C. gallinarum-like haplotypes (chicken genotype) and C. bettencourti-like haplotypes, including ST1 (rat genotype) and ST2 (rat-buffalo genotype), were also identified.

Conclusions: The genetic references registered in this study, along with the revealed molecular classification of Chilomastix spp., are crucial for understanding the genetic diversity and host-specific dynamics of these parasites in endemic regions.