Naegleria fowleri is a free-living amoeba that causes a rare but almost always fatal brain infection known as primary amoebic meningoencephalitis (PAM). Although amphotericin B (AmB) is considered the primary treatment for PAM, it is often recommended in combination with several other drugs due to side effects associated with high concentrations. In this study, we investigated whether histone deacetylase inhibitors (HDACis) enhance the amoebicidal activity of AmB against N. fowleri. Anti-proliferative and cytotoxic activities were assessed using the cell counting kit and lactate dehydrogenase assays, respectively, and apoptosis induction was evaluated by flow cytometry. Class-specific HDACis, including class I inhibitors MS275 and MGCD0103 and a class II inhibitor MC1568, showed minimal effects on trophozoite viability. In contrast, the pan-HDACis SAHA and JNJ significantly reduced trophozoite viability in a dose- and time-dependent manner. Furthermore, 10 μM SAHA and JNJ significantly reduced the encystation ratio of N. fowleri. Combined treatment with low doses of HDACi (1 μM) and AmB (0.5 μM) produced stronger amoebicidal and pro-apoptotic effects than either agent alone. These combination treatments also exhibited low cytopathic effects on human brain tumor cells. These findings suggest that SAHA and JNJ, particularly in combination with AmB, hold promise as therapeutic candidates against N. fowleri infection while potentially mitigating the severe side effects associated with AmB.

Naegleria fowleri, the causative agent of primary amoebic meningoencephalitis, produces an acute infection of the central nervous system. Although human cases are rare, the rapid progression and more than 95% mortality rate have made the disease an important subject of neuropathological research. Here, we discuss an integrated comparative review of the pathology of N. fowleri infection in humans and animals, highlighting conserved routes of neuroinvasion, shared patterns of necrotising and haemorrhagic meningoencephalitis, and cross-species similarities in inflammatory and vascular injury. The broadly consistent pathological features caused by this devastating pathogen, observed across a wide range of mammals, confirm the validity of animal models for both mechanistic studies and therapeutic development.

The pathogenic free-living amoeba Naegleria fowleri is the cause of primary amebic meningoencephalitis (PAM), a central nervous system infection that is almost always lethal. One of the unusual features of the amoebae is the presence of ~4000 copies of a nucleolar-localized closed circular extrachromosomal ribosomal DNA element (CERE) that encodes the cell's ribosomal RNA repertoire. It has historically been challenging to purify large quantities of CERE, limiting our understanding of the nucleic acid. Here, we describe a methodology for CERE purification that improves yield, reduces processing times, and maintains the integrity of the plasmid. This approach will enable the study of this unique DNA architecture, advancing our understanding of the pathobiology of the organism.

Neuroinvasive free-living amoebae (FLA), particularly Naegleria fowleri and Acanthamoeba spp., are responsible for rare but devastating infections of the central nervous system (CNS). Approximately 480 cases of primary amoebic meningoencephalitis (PAM) and fewer than 200 well-documented cases of Acanthamoeba-associated granulomatous amoebic encephalitis (GAE) have been reported worldwide. Mortality rates frequently exceed 90%. PAM typically develops following exposure to warm freshwater contaminated with N. fowleri and progresses rapidly in otherwise healthy individuals. In contrast, GAE usually follows a more indolent course and occurs predominantly in immunocompromised hosts. Despite their distinct clinical courses, both infections are characterized by CNS invasion, amoeba-mediated tissue destruction, blood-brain barrier (BBB) disruption, and host inflammatory responses. These processes drive neuroinflammation, neuronal injury, and neurological deterioration. Early diagnosis remains challenging because clinical manifestations are nonspecific and disease progression can be either fulminant or initially subtle. Therapeutic management is hindered by poor CNS drug penetration, limited efficacy of currently available therapies, treatment-related toxicity, and the absence of standardized treatment protocols or controlled clinical trials. This narrative review critically synthesizes current evidence on CNS invasion, neuroinflammation, neuropathology, diagnostic challenges, and therapeutic strategies in neuroinvasive FLA infections. It also highlights key translational priorities, including earlier diagnosis, standardized treatment protocols, stronger clinical evidence, and improved CNS-targeted drug delivery.

Congenital toxoplasmosis has become rare in France. Primary prevention is based on hygiene and dietary measures. Serological screening is mandatory in France. When maternal infection occurs in pregnancy, prophylactic treatment (spiramycin for first trimester; pyrimethamine and sulfonamide for second or third-trimester infections) reduces the risk of placental transmission. Prenatal diagnosis is performed by amniocentesis. In case of congenital toxoplasmosis, prompt treatment with pyrimethamine and sulphonamide reduces the risks of brain or eye damage; long-term follow-up of the child is required.

Cerebral malaria (CM), the most severe neurological manifestation of Plasmodium infection, is characterized by microglial activation that plays a pivotal role in initiating pathogenic neuroinflammatory cascades. Tunneling nanotubes (TNTs) are dynamic F-actin-based intercellular connections which transfer mitochondria and pathogenic factors. Although TNTs have been implicated in various neuropathological conditions, their precise involvement in CM pathogenesis, particularly in relation to microglial activation, remains undefined. In this study, single-cell RNA-sequencing (scRNA-seq) revealed significant dysregulation of TNT-associated genes and actin cytoskeleton pathway remodeling in microglia of ECM model. In vitro studies demonstrated that Plasmodium-infected red blood cells (pRBCs)-stimulated primary microglia formed extensive F-actin-rich tunneling nanotubes, which mediated the bidirectional transfer for mitochondria and facilitated intercellular trafficking of lysosomal contents and malarial pigment. These TNT-mediated intercellular communication amplified microglial activation, as evidenced by: (i) lipid peroxidation, (ii) mitochondrial dysfunction, and (iii) autophagosome (LC3+) accumulation. This process further amplifies neuroinflammation through TNFα/IL-6 secretion and expansion of CD45high microglial populations. Pharmacological TNT inhibition restores microglial homeostasis in ECM model. In conclusion, TNTs mediate neuroinflammation in the ECM model by transferring mitochondria and malarial pigment between microglia. Although mitochondrial transfer may transiently support cellular homeostasis, progressive malarial pigment accumulation triggers lipid metabolism dysregulation and amplified neuroinflammation. Inhibiting TNTs formation attenuates microglial hyperactivation, highlighting targeted regulation of TNT-mediated intercellular communication as a potential therapeutic approach for CM-associated neuropathology.

Primary amebic meningoencephalitis (PAM), caused by the thermophilic amoeba Naegleria fowleri, is a rare but almost invariably fatal neurological infection. Unlike classical communicable diseases, PAM transmission is exclusively environmentally driven, with no human-to-human transmission. This paper develops and rigorously analyzes a novel susceptible-exposed-infected-dead-water (SEIDW) epidemic model that explicitly couples human infection dynamics with an environmental reservoir of N. fowleri. We establish the fundamental properties of the model including positivity, boundedness, and invariance of solutions. Unlike classical SIR-type models where the basic reproduction number R e derives from human-to-human transmission cycles, the one-directional transmission structure of PAM (environment → human only, with no human-to-environment feedback) renders the standard next-generation matrix approach inapplicable. We instead derive the environmental reproduction number R e = r W / (δ W + κ C w) via Jacobian eigenvalue analysis and demonstrate that it serves as a sharp threshold parameter: when R e < 1 , the disease-free equilibrium is globally asymptotically stable; when R e > 1 , a unique endemic equilibrium exists and is globally asymptotically stable under biologically plausible conditions. We conduct a complete bifurcation analysis revealing that the model undergoes a forward transcritical bifurcation at R e = 1 . Sensitivity analysis reveals that R e depends exclusively on environmental parameters (r W , δ W , κC w), while human parameters (β, σ, α) affect disease burden but not persistence-a finding with profound public health implications. We extend the model to include time-dependent optimal control strategies representing behavioral interventions, environmental sanitation, and personal protective measures. Pontryagin's maximum principle yields characterization of optimal controls, and numerical simulations demonstrate that integrated environmental management is substantially more effective than clinical interventions alone. PRCC and variance-based sensitivity analysis via Latin Hypercube Sampling confirms model robustness under parameter variability. This mathematical framework provides rigorous foundations for designing evidence-based PAM prevention strategies.

Naegleria fowleri is a highly lethal free-living protozoan responsible for primary amoebic meningoencephalitis (PAM), a rapidly progressive central nervous system infection with a mortality rate exceeding 95%, for which no licensed vaccine or effective preventive therapy currently exists. The absence of prophylactic strategies demands development of novel immunopharmacological interventions. In this study, a comprehensive pan-genomic and structure-guided immunoinformatics approach was employed to design a multi-epitope vaccine candidate against N. fowleri. Four genomes of N. fowleri were subjected to an integrative pan-genomic-immunoinformatics pipeline involving orthologous clustering, subtractive genomics, and immunological relevance screening. From 1427 predicted membrane proteins, 885 antigenic, non-allergenic, and non-toxic candidates were identified. Epitope prediction yielded 7 B-cell epitopes, 26 MHC class I-restricted CTL epitopes, and 22 MHC class II-restricted HTL epitopes, which were assembled into a multi-epitope vaccine construct with immunostimulatory adjuvants. The resulting 320-amino acid construct demonstrated high antigenicity and global population coverage of 91.75%. Structural validation confirmed 98.9% of residues in favorable Ramachandran regions and an ERRAT quality score of 92.484. Molecular docking with Toll-like receptor 3 (TLR3) revealed a highly stable complex with a weighted energy score of - 1475.4 kcal/mol, featuring 24 hydrogen bonds and 5 salt bridges. Molecular dynamics simulations over 100 ns demonstrated structural stability with low RMSD and RMSF values, indicating dynamic stability and coordinated residue motions. Immune simulations predicted strong humoral and cellular immune responses with sustained antibody levels and memory cell generation. Codon optimization achieved a CAI of 0.99 and 53.4% GC content, supporting heterologous expression in Escherichia coli. This multi-epitope vaccine candidate exhibits strong immunogenic potential, structural stability, and favorable interactions with innate immune receptors, positioning it as a promising candidate for experimental validation against N. fowleri infection.

The genus Naegleria comprises free-living amoebae characterized as amphizoic and ubiquitous microorganisms. Naegleria fowleri is the only species pathogenic to humans, causing primary amebic meningoencephalitis. The 26S proteasome represents the principal catalytic complex responsible for the degradation and recycling of intracellular proteins in eukaryotic cells. This complex consists of the 20S and 19S proteasome subunits, with the latter involved in the recognition and processing of ubiquitinated proteins and their delivery to the degradation site. Although the 26S proteasome has been characterized in various pathogenic protozoa, only the 20S proteasome has been studied within the genus Naegleria. The objective of this study was to demonstrate the presence of 19S subunits in N. fowleri. Bioinformatics analyses were employed to evaluate the presence and homology of non-ATPase subunits (Rpn10, Rpn11, and Rpn13) and ATPase subunits (Rpt2, Rpt3, and Rpt5). Additionally, the presence, localization, and correlation of 19S proteasome proteins with the 20S proteasome were assessed using experimental approaches. The results indicate that N. fowleri possesses proteins corresponding to the 19S proteasome, which, together with the 20S core particle, contribute to the formation of the 26S proteasome.

Objective:Naegleria fowleri, known as the brain-eating amoeba, is a thermophilic, freshwater amoeba causing primary amoebic meningoencephalitis (PAM), a disease that progresses rapidly from symptom onset to death. Climate change is causing surface water temperatures to increase, providing a hospitable environment for N. fowleri, possibly increasing risk factors for PAM. This review synthesizes the peer-reviewed biomedical literature published between January 2012 and December 2025, examining the risk of N. fowleri infection in the context of a warming climate. Methods: A scoping review was conducted searching PubMed, Scopus, and Environment Complete. Data were extracted using a structured coding framework, and risk dimensions were derived inductively during the coding process. Results: Twenty-seven articles met inclusion criteria. Analysis revealed four dimensions of risk (environmental, behavioral, clinical/biological, and infrastructural). The environmental risk dimension highlighted gaps in understanding geographic range expansion and organism ecology. The behavioral dimension identified recreational water exposure, sinus rinsing, and travel as primary risk drivers. The clinical/biological dimension highlighted the need for standards and capacity in diagnosis and treatment, as well as research into pathogenicity. The infrastructural dimension identified gaps in water distribution system surveillance and disinfectant efficacy at high temperatures. Discussion: This review maps environmental, behavioral, clinical/biological, and infrastructural dimensions of N. fowleri disease risk onto a hazard/exposure/vulnerability framework, highlighting major gaps surrounding exposure and vulnerability. Uncertainties remain in hazard habitat favorability factors, human behavior, and water distribution systems. Emphasis should be placed on characterizing the hazard through environmental testing and determining geographic range, and addressing vulnerability by increasing clinician awareness, which serves double duty in both initiating early empiric treatment and efforts to quantify true disease burden.

We discuss some of the major cerebral parasites responsible for neglected diseases affecting humanity, especially in low-income countries. The World Health Organization states that cerebral malaria caused by Plasmodium falciparum is responsible for over 20% of deaths, especially in paediatric age. In addition to microscopy and molecular techniques, diagnosis can also be made with fundus magnetic resonance imaging and retinal fluorescein angiography, which have recently proven useful for assessing and understanding the clinical status of brain malaria. Currently, the best available treatment is combination therapy with artemisinin derivatives. Experimental drugs that prevent the development of malaria and blood-brain barrier dysfunction will be discussed. Neurocysticercosis is the most common helminthic infection of the central nervous system and a major cause of acquired epilepsy in resource-limited countries. Imported cases are increasing in Europe. Neuroimaging supported by immunodiagnostic tests with purified parasite antigens is the most important diagnostic test. Clinical management includes antiparasitic treatment, antiepileptic drugs, anti-inflammatories and surgery for obstructive hydrocephalus. In cerebral hydatidosis, brain involvement occurs primarily in childhood. Diagnosis is usually made through clinical, laboratory and imaging tests. The opportunistic toxoplasmic encephalitis is due to reactivation and can still be observed in AIDS patients with low access to antiretroviral therapy. Less common cerebral parasitic diseases include schistosomiasis, toxocariasis and amoebiasis, of which primary amoebic meningoencephalitis (Naegleria fowleri) has a very high mortality rate and treatment remains challenging in the absence of new drugs. The modification of existing drugs using nanotechnology offers promising prospects in the development of therapeutic interventions against these parasitic diseases.

The genus Naegleria is a taxonomic subfamily consisting of 47 free-living amoebae. The genus can be found in warm aqueous or soil habitats worldwide. The species Naegleria fowleri is probably the best-known species of this genus. As a facultative parasite, the protist is not dependent on hosts to complete its life cycle. However, it can infect humans by entering the nose during water contact, such as swimming, and travel along the olfactory nerve to the brain. There it causes a purulent meningitis (primary amoebic meningoencephalitis or PAME). Symptoms are severe and death usually occurs within the first week. PAME is a frightening infectious disease for which there is neither a proven cure nor a vaccine. In order to contain the disease and give patients any chance to survival, action must be taken quickly. A rapid diagnosis is therefore crucial. PAME is diagnosed by the detection of amoebae in the liquor and later in the cerebrospinal fluid. For this purpose, CSF samples are cultured and stained and finally examined microscopically. Molecular techniques such as PCR or ELISA support the microscopic analysis and secure the diagnosis.

Primary amoebic meningoencephalitis (PAM) or "brain-eating amoeba disease" is a relatively rare but typically fatal infectious disease of increasing global concern. Discovery of PAM and that Naegleria fowleri is the causative agent responsible are frequently credited to a paper published by the Australian pathologists Malcolm Fowler and Rodney F. Carter in 1965. It was significant as confirmation of an earlier suspicion that free-living, non-parasitic amoebae may be opportunistic pathogens of the human central nervous system. Like many discoveries, however, the historical details are rather more complicated and involved a number of researchers and clinicians working over a decade from 1958 to 1971. Philosophical accounts of scientific discovery since Kuhn (Science, 136, 760-764, 1962) agree that discovery requires both recognition that something exists and understanding what it is. But there is little agreement about how much or what kind of understanding is required. This paper (i) excavates the complex array of observations, inferences, experiments, re-evaluations, and public statements by a number of scientific researchers and physicians that collectively resulted in the recognition of PAM as a novel form of central nervous system infection caused by a novel species of free-living amoeba; and (ii) considers how well several recent accounts of discovery apply to these achievements.