Acta tropica最新文献

Background: India has made remarkable progress in lowering the incidence of malaria cases. Epidemiological investigation of performance matrices and spatiotemporal characteristics, particularly at the district and sub-district levels is crucial for proper allocation of resources. This study aims to identify hotspot in context of malaria endemic Sonbhadra district to set an exemplar to guide targeted interventions.

Methods: Malaria surveillance data spanning 2017 to 2024, were analyzed to estimate future case scenario. Kulldorf scanning with discrete Poission probability model was used for detection of high-risk malaria clusters. Mean Annual Rate of Change (AROC) and Maximum AROC were calculated to project the year of zero malaria case status.

Results: A total of 18217 malaria cases were reported during 2017 to 2024 from this district. A decrease was observed in test positivity rates (TPR) with 95% reduction in cases during the study period. Annual parasite incidences (API) decreased from 2.7 in 2017 to 0.1 in 2024 and annual falciparum incidence (AFI) showed a late-period fluctuation, rising to 0.09 in 2024 after a near total suppression in 2022 and 2023. The most significant malaria hotspot was present at western part of this district at Chopan block. Presence of high-risk clusters of both Plasmodium falciparum and P. vivax at sub-district level was alarming for the maintenance of sustainable malaria reduction goals.

Conclusion: This study provides an insight to identify local malaria foci at micro-level for evidence-based targeting of resources using spatiotemporal epidemiology, and facilitating multisectoral coordination involving community to accelerate micro-level elimination targets.

African swine fever virus (ASFV), the sole known DNA arbovirus, causes acute hemorrhagic fever in domestic pigs with case fatality rates approaching case fatality 100%. While less contagiously transmitted than viral agents like foot-and-mouth disease virus, ASFV's epidemiological significance stems from its complex transmission ecology involving soft ticks. Ornithodoros ticks are established biological vectors, with eight species confirmed globally. However, potential vectors in China, where Ornithodoros lahorensis (O. lahorensis) is endemic and remain uncharacterized. This study tested the hypothesis that O. lahorensis serves as a competent biological vector for ASFV under laboratory conditions. We hypothesized that vector competence, defined as the ability to acquire, maintain, and transmit infectious African swine fever virus, differs between soft (O. lahorensis, Argas persicus) and hard (H. longicornis, R. sanguineus, D. silvarum) tick species, and tested this using experimental transmission assays. Results demonstrated that O. lahorensis efficiently supported transstadial persistence and transovarial transmission of ASFV. Naïve pigs exposed to infected O. lahorensis developed acute ASF with case fatality 100%. Viral replication in salivary glands, midgut, and Malpighian tubules was confirmed by qPCR and transmission electron microscopy, with no significant fitness costs to ticks. In contrast, A. persicus and all ixodid species failed to transmit. Here identifies O. lahorensis as a critical ASFV vector in China, informing targeted acaricidal control in endemic regions.

Minute intestinal flukes in the family Plagiorchiidae have received limited research attention, leading to a lack of molecular data and life cycle details. In this study, nuclear ribosomal DNA (rDNA), mitochondrial genome, and morphological analyses were integrated to characterize Plagiorchis species infecting the lymnaeid snail Orientogalba (Austropeplea) viridis in Thailand. Analysis of the nuclear rDNA region (18S, ITS1, 5.8S, ITS2, and 28S) provided complementary genetic evidence supporting the taxonomic placement within Plagiorchis. The complete mitochondrial genome was 14,051 bp in length and exhibited a gene content and organization typical of Plagiorchis, comprising 12 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes (12S and 16S rRNAs), and non-coding regions, with all genes transcribed in the same direction. ATG was the predominant initiation codon, with GTG also used, whereas TAG and TAA were the only termination codons detected. Phylogenetic analyses based on mitochondrial sequences placed the identified Plagiorchis PYO isolate as a sister lineage to P. multiglandularis, indicating a close evolutionary relationship. Experimental infections and detailed morphological examinations of larval stages in both the snail host and the second intermediate host identified culicine mosquito larvae as a potential second intermediate host. This study provides the first combined nuclear rDNA and complete mitochondrial genome data for Plagiorchis spp. in Thailand, together with comprehensive morphological documentation of larval stages from redia to metacercaria. Collectively, these findings expand genetic resources for Plagiorchis, clarify key aspects of its life cycle, and establish a robust framework for molecular identification and future evolutionary and epidemiological studies.

Avian haemosporidians (order Haemosporida), including the genera Plasmodium and Haemoproteus, are widespread vector-borne parasites that infect a broad range of bird species and can adversely affect host fitness, survival, and population dynamics. Although the Neotropics harbor a high diversity of avian hemoparasites, molecular studies in Colombia remain scarce, particularly in highly threatened ecosystems such as tropical dry forests. This study aimed to evaluate the presence and diversity of avian hemoparasites in birds inhabiting an urban fragment of tropical dry forest in northern Colombia. Birds were captured using mist nets, and blood samples were obtained by brachial or jugular venipuncture. Samples were collected from 217 individuals, comprising 27 resident species and 7 boreal migratory species. Genomic DNA was extracted and screened for haemosporidian infections using PCR targeting the cytochrome b (Cytb) and 18SrRNA genes. Phylogenetic analyses were performed using maximum likelihood and Bayesian inference. Infections with Haemoproteus (Parahaemoproteus) spp. or Plasmodium spp. were detected in eleven individuals representing six species, including both resident and migratory birds, resulting in an overall prevalence of 5.1%. Several of the documented host-parasite associations represent new records for Colombia. This study highlights the potential of tropical dry forest fragments to reveal novel avian host-parasite interactions and underscores the importance of integrating multiple molecular markers for accurate hemoparasite identification.

In tropical regions, arboviruses and Plasmodium co-circulate frequently, and co-infection with these pathogens can complicate clinical diagnosis. This study aimed to estimate the prevalence of arbovirus and malaria coinfection and identify associated risk factors. A cross-sectional study was conducted among patients with suspected dengue or malaria who presented at Centres Médicaux avec Antenne Chirurgicale (CMA) of Do (Bobo-Dioulasso) and Houndé between June and September 2023. Blood samples were collected from participants. Serum was used for dengue rapid diagnostic test and RT-PCR assays for molecular detection of dengue and chikungunya virus. Malaria diagnosis was performed through identification of Plasmodium in thick and thin blood smears by microscopy and confirmed by PCR assay using whole blood. C-reactive protein (CRP) level was measured in samples from dengue and malaria coinfection and each mono-infection group. Serology-based coinfection was considered indicative of recent/past dengue exposure, whereas RT-PCR and PCR-based detection indicated acute dengue and malaria infection. A total of 408 samples were analyzed, and the prevalence of coinfection between recent dengue infection (NS1 and/or IgM positive) and malaria (microscopy and/or PCR positive) was 17. 64% (72/408). Acute DENV (RT-PCR positive) and malaria co-infections were observed in 7.10% (29/408) of cases. Among RT-PCR positive dengue cases, coinfection with Plasmodium detected by PCR was observed in 100% (29/29), whereas 68.96% (20/29) were positive by malaria microscopy. Elevated axillary temperature and high CRP level (mean 83.79 mg/l) were associated with acute dengue and malaria coinfection. Multiplex RT-PCR improved the detection of acute dengue-malaria coinfection.

Cobras (Naja spp.) account for a significant number of snakebite incidents in Thailand. The monocled cobra (Naja kaouthia) has historically been considered the only non-spitting species, but recent evidence indicates population-level diversification in central and southern regions. Additionally, a newly described non-spitting species, the mountain cobra (Naja fuxi), has been identified in mountainous areas. This study investigates venom variation among Thai Naja species and populations and evaluates the efficacy of monovalent and polyvalent Thai antivenoms. Proteomic analyses revealed that three-finger toxins dominate Naja venoms, whereas N. fuxi exhibits a distinct profile enriched in snake venom metalloproteinases and cysteine-rich secretory proteins, suggesting evolutionary divergence. Electrophoretic and enzymatic assays demonstrated species- and population-specific differences in phospholipase A₂, acetylcholinesterase, hyaluronidase, L-amino acid oxidase, phosphodiesterase, and protease activities. Cytotoxicity assays on human fibroblasts and mouse myoblasts showed that N. kaouthia (southern) and N. fuxi venoms caused the most potent and time-dependent cell damage, whereas central N. kaouthia and king cobra (Ophiophagus hannah) venoms were less cytotoxic. Immunoreactivity and neutralisation assays indicated that the species-specific monovalent antivenom effectively binds and neutralises cobra venoms, while neuro-polyvalent antivenom provides moderate cross-protection, and haemato-polyvalent antivenom is highly specific to viperid venom. These findings reveal substantial inter- and intraspecific venom variation in Thai cobras, emphasising the importance of population-level considerations in antivenom design and snakebite management. Continuous evaluation of venom composition and antivenom efficacy is essential to optimise clinical outcomes across Thailand's diverse landscapes.

Specificity patterns of host parasite interactions is a key component in disease ecology, varying considerably among groups. Hematophagous flies of families Streblidae and Nycteribiidae are obligate ectoparasites of bats exhibiting high host specificity from millions of years of coevolution. Despite Brazilian megadiversity of bats and parasitic flies, knowledge about these interactions in fragmented urban environments remains limited, crucial for understanding urbanization effects. This study characterized diversity and network structure between bats and ectoparasitic flies (Diptera: Streblidae) in an urban Atlantic Forest fragment in São Paulo city. Over twelve months (from October 2015 to September 2016), 68 phyllostomid bats from three species were captured: Artibeus lituratus (n=28), A. fimbriatus (n=14), and Sturnira lilium (n=26). All individuals were parasitized (prevalence=100%), harbouring 212 flies from five Streblidae species: Paratrichobius longicrus (n=97), Megistopoda aranea (n=45), M. proxima (n=35), Aspidoptera falcata (n=34), and A. phyllostomatis (n=1). Prevalence and abundance of fly species differed significantly among hosts, with P. longicrus mainly associated with A. lituratus, M. aranea with A. fimbriatus, and M. proxima and A. falcata with S. lilium. The interaction network showed moderate specialization (H₂'=0.742) and modularity (Q=0.544), with values lower than preserved Neotropical forests. Fly species such as P. longicrus may act as bridge vector among bat species. Our results contribute to understanding host-parasite interactions in Neotropical urban environments and emphasize ecological importance in managing urban green areas harboring functional parasite communities.

Viral load non-suppression remains a major challenge among people living with HIV receiving antiretroviral therapy, despite widespread use of fixed-dose combination regimens. Evidence on factors with viral load non-suppression in eastern Indonesia remains limited. The study aims to assess the prevalence of viral load non-suppression and its associated factors among people living with HIV receiving fixed dose combination regimen in Jayapura City, Indonesia. A cross-sectional study was conducted among HIV patients receiving antiretroviral therapy from March to June 2024. Viral load status was classified as suppressed or non-suppressed. Bivariate associations were assessed using Chi-square tests and presented as prevalence ratios (PRs) with 95% confidence intervals (CIs). Multivariable analysis was examined using logistic regression, with result reported as adjusted odds ratios (aORs). In bivariate analysis, viral load non-suppression was more common among participants aged > 35 years (PR = 1.91;95% CI: 1.20-3.05), those who were underweight (PR = 1.81; 95% CI: 1.09-3.01), and individuals on the TLE regimen compared with TLD (PR=1.81; 95% CI: 1.02-3.21). In multivariable analysis, participants aged 17-35 years had lower odds of viral load non-suppression (aOR = 0.30; 95% CI: 0.12-0.75), whereas receipt of the TLE regimen remained independently associated with higher odds of non-suppression (aOR = 3.10; 95% CI: 1.19-8.11). Body mass index showed no independent association after adjustment. Viral load non-suppression was associated with age and antiretroviral regimen, with a robust association observed for the TLE regimen. These findings highlight the need for careful regimen selection and enhanced monitoring in routine HIV management.

Climate change is altering ecosystems, posing a risk of major impact for both human and animal health. Emerging zoonotic diseases, such as anthrax, are particularly vulnerable to changes in climate and biodiversity. anthrax, a classic zoonotic disease, disproportionately affects vulnerable pastoralist communities. This research assessed how changing climatic variables influence the geographical spread of anthrax outbreaks in the Indian condition, a region confronting rapid climate impacts. The study also compared the effect of climate variables with traditional factors like livestock population distribution and soil-moisture balance in determining anthrax risk. MaxEnt, a machine learning model which maximizes entropy of the probability distribution was used to predict anthrax suitability under Indian climatic conditions. The results identified climatic variables like rainfall, soil moisture, soil pH, temperature humidity index (THI), land surface temperature (LST) and livestock density are critical in modeling anthrax suitability. These outcomes emphasize the key role of warming climatic events driven by raising temperature and more frequent and intense extreme weather events heatwaves, droughts and floods in shaping anthrax ecology in India. Further indicate that strategies targeting conserving megafauna diversity in agriculture ecosystems and enhancing livestock health in small and medium-sized herds could mitigate the disease's risks. This study underscores the growing significance of climate in anthrax distribution and suggests that biodiversity conservation and better livestock management could play key roles in reducing future anthrax incidences.

Echinococcosis in humans caused by hydatid cyst of Echinococcus spp., remains a significant public health concern in Mongolia. In this study, we aimed to characterize the epidemiology, histopathological features, and molecular diversity of Echinococcus isolates from human infections. A retrospective analysis of surgically confirmed cases diagnosed between 2010 and 2024 was conducted. A histopathological examination of resected or biopsied cyst material was employed to assess cyst morphology and associated tissue responses. Molecular identification was performed using PCR amplification and sequencing of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene, followed by Bayesian phylogenetic analysis. A total of 311 human echinococcosis cases from multiple provinces were analyzed. Furthermore, COX1 sequences identified 181 isolates of Echinococcus granulosus sensu stricto (G1), 106 of E. canadensis (G6/7), 19 of E. canadensis (G10), and 5 of E. multilocularis, revealing 11 haplotypes. Geographic clustering of selected genotypes was observed. Bayesian phylogenetic reconstruction demonstrated clustering of Mongolian isolates within established Echinococcus lineages. Time-scaled analyses provided insights into the relative temporal relationships among lineages; however, divergence time estimates were interpreted cautiously owing to reliance on a substitution rate prior and single mitochondrial marker. These findings provide updated epidemiological and molecular data on human echinococcosis in Mongolia. However, given the single-locus design and exclusive use of human-derived samples, interpretations regarding transmission dynamics remain inferential and require confirmation through integrated host-based studies.