- Naegleria fowleri. [Journal Article]
- TPTrends Parasitol 2019 Jul 09
- Primary Amebic Meningoencephalitis: A Case Report. [Journal Article]
- KJKorean J Parasitol 2019; 57(3):291-294
- Primary amebic encephalitis (PAM) is a devastating central nervous system infection caused by Naegleria fowleri, a free-living amoeba, which can survive in soil and warm fresh water. Here, a 43-year-…
Primary amebic encephalitis (PAM) is a devastating central nervous system infection caused by Naegleria fowleri, a free-living amoeba, which can survive in soil and warm fresh water. Here, a 43-year-old healthy male was exposed to warm freshwater 5 days before the symptom onset. He rapidly developed severe cerebral edema before the diagnosis of PAM and was treated with intravenous conventional amphotericin B while died of terminal cerebral hernia finally. Comparing the patients with PAM who has similar clinical symptoms to those with other common types of meningoencephalitis, this infection is probably curable if treated early and aggressively. PAM should be considered in the differential diagnosis of purulent meningoencephalitis, especially in patients with recent freshwater-related activities during the hot season.
- Primary amebic meningoencephalomyelitis caused by Naegleria fowleri in a south-central black rhinoceros (Diceros bicornis minor). [Journal Article]
- JAJ Am Vet Med Assoc 2019 Jul 15; 255(2):219-223
- CASE DESCRIPTION A 20-year-old female south-central black rhinoceros (Diceros bicornis minor) was evaluated because of an acute onset of CNS deficits. CLINICAL FINDINGS The rhinoceros had no history…
CASE DESCRIPTION A 20-year-old female south-central black rhinoceros (Diceros bicornis minor) was evaluated because of an acute onset of CNS deficits. CLINICAL FINDINGS The rhinoceros had no history of illness. Clinical signs included acute lethargy, ataxia, and decreased appetite. Hematologic abnormalities included leukocytosis with neutrophilia and a profound left shift. Results of serum biochemical analysis revealed hypophosphatemia but no other abnormalities. Results of a quantitative PCR assay for West Nile virus and an assay for anti-Neosporum caninum antibodies in serum were negative; the patient was seropositive for multiple Leptospira serovars. TREATMENT AND OUTCOME Antimicrobials and anti-inflammatory agents were administered, but the condition of the rhinoceros worsened overnight; despite treatment with additional anti-inflammatory and antimicrobial agents, IV fluids, and thiamine, it became obtunded and died of respiratory arrest ≤ 24 hours later. Necropsy revealed severe, diffuse, suppurative, and histiocytic meningo-encephalomyelitis involving the cerebrum, cerebellum, and spinal cord. Amebic trophozoites were observed on histologic examination of affected tissue. Infection with Naegleria fowleri was confirmed by results of immuno-histochemical analysis and a multiplex real-time PCR assay. CLINICAL RELEVANCE Findings suggested that south-central black rhinoceros are susceptible to the free-living ameba N fowleri. Ameba-induced meningoencephalomyelitis should be considered as a differential diagnosis for rhinoceros that have an acute onset of neurologic signs. Diagnosis of N fowleri infection in an animal has a profound public health impact because of potential human exposure from the environment and the high fatality rate in people with N fowleri infection.
- Pathogenic free-living amoebic encephalitis in Japan. [Review]
- NNeuropathology 2019 Jun 26
- Over 600 cases of amoebic encephalitis caused by pathogenic free-living amoebas (Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri) have been reported worldwide, and in Japan, 24 case…
Over 600 cases of amoebic encephalitis caused by pathogenic free-living amoebas (Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri) have been reported worldwide, and in Japan, 24 cases have been reported from the first case in 1976 up to 2018. Among these cases, 18 were caused by B. mandrillaris, four by Acanthamoeba spp., one by N. fowleri, and one was of unknown etiology. Additionally, eight cases were diagnosed with encephalitis due to pathogenic free-living amoebas before death, but only three cases were successfully treated. Unfortunately, all other cases were diagnosed by autopsy. These facts indicate that an adequate diagnosis is difficult, because encephalitis due to pathogenic free-living amoebas does not show typical symptoms or laboratory findings. Moreover, because the number of cases is limited, other cases might have been missed outside of those diagnosed by autopsy. Cases of encephalitis caused by B. mandrillaris have been reported from all over Japan, with B. mandrillaris recently isolated from soil in Aomori prefecture. Therefore, encephalitis caused by pathogenic free-living amoebas should be added to the differential diagnosis of encephalitis patients.
- Meningoencephalitis due to Naegleria fowleri in cattle in southern Brazil. [Journal Article]
- RBRev Bras Parasitol Vet 2019 Jun 06
- Naegleria fowleri is a free-living amoeba commonly found in the environment, mainly in fresh water and soil. This protozoon is occasionally involved in cases of fatal central nervous system disease i…
Naegleria fowleri is a free-living amoeba commonly found in the environment, mainly in fresh water and soil. This protozoon is occasionally involved in cases of fatal central nervous system disease in humans and other animal species. We describe here a case of meningoencephalitis due to Naegleria fowleri in cattle, in southern Brazil. A four-year-old Angus cow presented a clinical history of initial mild neurological signs that progressed to paddling movements, opisthotonus and lateral recumbency after five days. This animal had been kept in an irrigated rice stubble paddock. Grossly, the main lesions consisted of multiple areas of malacia in the right olfactory bulb, piriform lobes, hippocampus, frontal lobe cortex and fornix, along with severe thickening of the mesencephalon and rhombencephalon leptomeninges. Microscopically, severe multifocal necrosuppurative and hemorrhagic meningoencephalitis associated with a large quantity of amoebic trophozoites was present. The latter were confirmed to be Naegleria spp., through immunohistochemistry. Based on the strong congruence with the histopathological data of known cases reported in the literature, a probable association with Naegleria fowleri was established. To our knowledge, this is only the second report of Naegleria fowleri-associated meningoencephalitis in cattle in South America, and it is the first in southern Brazil.
- Killer amoebas: Primary amoebic meningoencephalitis in a changing climate. [Journal Article]
- JJAAPA 2019; 32(6):30-35
- Primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri is a rare and deadly disease that requires prompt treatment with multiple therapies. Although N. fowleri previously was only foun…
Primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri is a rare and deadly disease that requires prompt treatment with multiple therapies. Although N. fowleri previously was only found in warmer areas, climate change appears to be contributing to its geographic spread. Clinicians should consider PAM when faced with a patient with meningitis, especially if the patient participates in outdoor water activities or practices nasal rinsing.
- Cellular characterization of actin gene concerned with contact-dependent mechanisms in Naegleria fowleri. [Journal Article]
- PIParasite Immunol 2019 May 11; :e12631
- Free-living amoeba, Naegleria fowleri, destroys target cells through contact-dependent mechanisms, such as phagocytosis and/or trogocytosis. A previous experiment showed that the nf-actin gene consis…
Free-living amoeba, Naegleria fowleri, destroys target cells through contact-dependent mechanisms, such as phagocytosis and/or trogocytosis. A previous experiment showed that the nf-actin gene consisted of 1.2 kbp, produced a 50.1 kDa recombinant protein (Nf-actin), and was localized on the cytoskeleton, pseudopodia and amoebastome. In this study, cellular characterization of the nf-actin gene concerned with contact-dependent mechanisms in N fowleri was performed. The nf-actin gene was amplified from a gene-cloned vector, pEXQP5-T7/NT TOPO. The nf-actin gene was introduced into the Ubi-pEGFP-C2 vector, and Ubi-pEGFP-C2/nf-actin was transfected into N fowleri trophozoites. Strong GFP fluorescence was detected in N fowleri trophozoites transfected with Ubi-pEGFP-C2/nf-actin. Expression of EGFP-Nf-actin protein was detected by Western blot analysis. The nf-actin-overexpressing N fowleri showed significantly increased adhesion activity against extracellular matrix components, fibronectin, collagen I and fibrinogen, compared with wild-type N fowleri. Moreover, nf-actin-overexpressing N fowleri showed increased phagocytic activity and cytotoxicity in comparison with wild-type N fowleri. In summary, the overexpressed nf-actin gene has an important function in ability to increase cell adhesion, cytotoxicity and phagocytosis by N fowleri.
- Neuroleptic Drug Targets a Brain-Eating Amoeba: Effects of Promethazine on Neurotropic Acanthamoeba castellanii. [Journal Article]
- ACACS Chem Neurosci 2019 Jun 19; 10(6):2868-2876
- Acanthamoeba spp. has recently been reported to express diverse group of ion channels and receptors that are expressed by human cells which bind drugs that are used in noninfectious diseases. Bioinfo…
Acanthamoeba spp. has recently been reported to express diverse group of ion channels and receptors that are expressed by human cells which bind drugs that are used in noninfectious diseases. Bioinformatics computational tools, growth assays, and 3D structural modeling have enabled the discovery of primitive muscarinic receptors, voltage-gated calcium channels, and ion transport pumps such as Na-K ATPase in this protist pathogen. The significance of the reported receptors and ion channels in the biology of Acanthamoeba is yet to be determined. We selected promethazine, which is a known antagonist of proteins like dopaminergic, histaminergic, muscarinic receptors, and calmodulin, to determine its effects on the growth and proliferation of trophozoites and cysts of Acanthamoeba spp. In order to elucidate the receptors involved in the effects produced by promethazine, we also performed individual experiments on Acanthamoeba trophozoites and cysts in the presence of the agonist of the above-mentioned receptors. Our results show that promethazine in the range of 60-100 μg/mL proved to be amoebicidal for Acanthamoeba trophozoites and at slightly higher doses ranging around 125-250 μg/mL also showed partial cysticidal effects. We also show the evidence of homology between the human targets of promethazine and similar targets in Acanthamoeba by the use of bioinformatic computational tools and 3D modeling. Promethazine and its structural analogs, because of being FDA-approved, have a wider margin of safety that can be tested as potential anti- Acanthamoeba agents in diseases like keratitis and encephalitis caused by this protist pathogen.
- trans-Cinnamic Acid Conjugated Gold Nanoparticles as Potent Therapeutics against Brain-Eating Amoeba Naegleria fowleri. [Journal Article]
- ACACS Chem Neurosci 2019 Jun 19; 10(6):2692-2696
- Primary amoebic meningoencephalitis (PAM), a deadly brain infection, is caused by brain-eating amoeba Naegleria fowleri. The current first line of treatment against PAM is a mixture of amphotericin B…
Primary amoebic meningoencephalitis (PAM), a deadly brain infection, is caused by brain-eating amoeba Naegleria fowleri. The current first line of treatment against PAM is a mixture of amphotericin B, rifampin, and miltefosine. Since, no single effective drug has been developed so far, the mortality rate is above 95%. Moreover, severe adverse side effects are associated with these drugs. Nanotechnology has provided several advances in biomedical applications especially in drug delivery and diagnosis. Herein, for the first time we report antiamoebic properties of cinnamic acid (CA) and gold nanoparticles conjugated with CA (CA-AuNPs) against N. fowleri. CA-AuNPs were successfully synthesized by sodium borohydride reduction of tetrachloroauric acid. Size and morphology were determined by atomic force microscopy (AFM) while the surface plasmon resonance band was analyzed by ultraviolet-visible (UV-vis) spectrophotometry for the characterization of the nanoparticles. Amoebicidal and cytopathogenicity (host cell cytotoxicity) assays revealed that both CA and CA-AuNPs displayed significant anti- N. fowleri properties (P < 0.05), whereas nanoparticles conjugation further enhanced the anti- N. fowleri effects of CA. This study established a potential drug lead, while CA-AuNPs appear to be promising candidate for drug discovery against PAM.
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- Proposals for Amendments in the Diagnosis and Treatment of Encephalitis caused by Free-living Amoebae. [Journal Article]
- IDInfect Disord Drug Targets 2019 Apr 05
- Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95-98%, a fraction that has not changed in the past decades. Pathogenic FLA include Acanthamoeba, Balamuthia mandrillar…
Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95-98%, a fraction that has not changed in the past decades. Pathogenic FLA include Acanthamoeba, Balamuthia mandrillaris, and Naegleria fowleri that are known to target the brain after an extra cerebral infection in the case of Acanthamoeba and Balamuthia mandrillaris, or directly the brain, as in the case of the Naegleria fowleri. The Acanthamoeba spp. and Balamuthia mandrillaris cause granulomatous amoebic encephalitis (GAE) while Naegleria fowleri, the so termed "brain eating amoeba" causes primary amoebic meningoencephalitis (PAM). The attempts to obtain a speedy diagnosis and an aggressive treatment protocol are the areas where advances can make a difference and reduce the mortality rates. At first, we highlight the reasons behind the diagnostic delays and treatment failures and provide proposals to establish a quick diagnosis in both PAM and GAE. Secondly, we emphasize the use of a transcribrial device, and a prompt, but vigilant surgical reduction of the intracranial pressure in these patients which could be life-saving. We also debate that an exudate obtained from the olfactory region by irrigation via a modified transcribrial device or by conventional methods, instead of a cerebrospinal fluid sample, could serve as a source of obtaining amoeba in PAM for a real-time polymerase chain reaction-based definitive diagnosis of PAM. Also introduced is the rationale that has the potential to deliver the drugs to the brain in patients with PAM and the GAE localized to the frontal lobe of the brain, by bypassing the blood brain barrier. We put forward these proposals for debate and deliberation to our fellow colleagues in order to spot the potential of their application to reduce the mortality rates caused by the rare but fatal encephalitis caused by these FLA.