Prompt diagnosis and extraordinary survival from Naegleria fowleri meningitis: A rare case report

Laboratory Diagnosis of Primary Amoebic Meningoencephalitis

Primary amebic meningoencephalitis (PAM) is a fulminant fatal human disease caused by the free-living amoeba Naegleria fowleri. Infection occurs after inhalation of water containing the amoeba, typically after swimming in bodies of warm freshwater. N. fowleri migrates to the brain where it incites meningoencephalitis and cerebral edema leading to death of the patient 7 to 10 days postinfection. Although the disease is rare, it is almost always fatal and believed to be underreported. The incidence of PAM in countries other than the United States is unclear and possibly on track to being an emerging disease. Poor prognosis is caused by rapid progression, suboptimal treatment, and underdiagnosis. As diagnosis is often performed postmortem and testing is only performed by a few laboratories, more accessible testing is necessary. This article reviews the current methods used in the screening and confirmation of PAM and makes recommendations for improved diagnostic practices and awareness.

The 4-Aminomethylphenoxy-Benzoxaborole AN3057 as a Potential Treatment Option for Primary Amoebic Meningoencephalitis

Primary amoebic meningoencephalitis is a rare but fatal central nervous system (CNS) disease caused by the "brain-eating amoeba" Naegleria fowleri. A major obstacle is the requirement for drugs with the ability to cross the blood-brain barrier, which are used in extremely high doses, cause severe side effects, and are usually ineffective. We discovered that the 4-aminomethylphenoxy-benzoxaborole AN3057 exhibits nanomolar potency against N. fowleri, and experimental treatment of infected mice significantly prolonged survival and demonstrated a 28% relapse-free cure rate.

Systematic Review of Brain-Eating Amoeba: A Decade Update

INTRODUCTION

Primary amoebic meningoencephalitis (PAM) is a rare but lethal infection of the brain caused by a eukaryote called Naegleria fowleri (N. fowleri). The aim of this review is to consolidate the recently published case reports of N. fowleri infection by describing its epidemiology and clinical features with the goal of ultimately disseminating this information to healthcare personnel.

METHODS

A comprehensive literature search was carried out using PubMed, Web of Science, Scopus, and OVID databases until 31 December 2022 by two independent reviewers. All studies from the year 2013 were extracted, and quality assessments were carried out meticulously prior to their inclusion in the final analysis.

RESULTS

A total of 21 studies were selected for qualitative analyses out of the 461 studies extracted. The cases were distributed globally, and 72.7% of the cases succumbed to mortality. The youngest case was an 11-day-old boy, while the eldest was a 75-year-old. Significant exposure to freshwater either from recreational activities or from a habit of irrigating the nostrils preceded onset. The symptoms at early presentation included fever, headache, and vomiting, while late sequalae showed neurological manifestation. An accurate diagnosis remains a challenge, as the symptoms mimic bacterial meningitis. Confirmatory tests include the direct visualisation of the amoeba or the use of the polymerase chain reaction method.

CONCLUSIONS

N. fowleri infection is rare but leads to PAM. Its occurrence is worldwide with a significant risk of fatality. The suggested probable case definition based on the findings is the acute onset of fever, headache, and vomiting with meningeal symptoms following exposure to freshwater within the previous 14 days. Continuous health promotion and health education activities for the public can help to improve knowledge and awareness prior to engagement in freshwater activities.

Case Report and Literature Review: Bacterial Meningoencephalitis or Not? Naegleria fowleri Related Primary Amoebic Meningoencephalitis in China

In China, a 9-year-old boy was transferred to the hospital with fever, vomiting, and headache. The disease rapidly deteriorated into vague consciousness. Applying conventional clinical examinations such as blood and cerebrospinal fluid (CSF) tests, the diagnosis of bacterial meningoencephalitis was first drawn, and expectant treatments were adopted immediately. However, the symptoms did not alleviate, adversely, this boy died 3 days after admission. Considering the skeptical points of the duration, such as the unknown infectious bacteria and the pathogen invasion path, blood and CSF samples were then sent for metagenomic next-generation sequencing (mNGS) to ascertain the cause of death. The 42,899 and 1,337 specific sequences of N. fowleri were detected by mNGS in the CSF sample and the blood sample, respectively. PCR results and pathological smear subsequently confirmed the mNGS detection. The patient was finally diagnosed as primary amoebic meningoencephalitis. Besides, in this article, 15 similar child infection cases in the past 10 years are summarized and analyzed to promote the early diagnosis of this rare disease.

Drugs used for the treatment of cerebral and disseminated infections caused by free-living amoebae

Free‐living amoebae (FLAs) are protozoa developing autonomously in diverse natural or artificial environments. The FLAs Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri represent a risk for human health as they can become pathogenic and cause severe cerebral infections, named granulomatous amoebic encephalitis (GAE), Balamuthia amoebic encephalitis (BAE), and primary amoebic meningoencephalitis (PAM), respectively. Additionally, Acanthamoeba sp. can also rarely disseminate to diverse organs, such as the skin, sinuses, or bones, and cause extracerebral disseminated acanthamebiasis (EDA). No consensus treatment has been established for cerebral FLA infections or EDA. The therapy of cerebral and disseminated FLA infections often empirically associates a large diversity of drugs, all exhibiting a high toxicity. Nevertheless, these pathologies lead to a high mortality, above 90% of the cases, even in the presence of a treatment. In the present work, a total of 474 clinical cases of FLA infections gathered from the literature allowed to determine the frequency of usage, as well as the efficacy of the main drugs and drug combinations used in the treatment of these pathologies. The efficacy of drug usage was determined based on the survival rate after drug administration. The most efficient drugs, drug combinations, and their mechanism of action were discussed in regard to the present recommendations for the treatment of GAE, EDA, BAE, and PAM. At the end, this review aims to provide a useful tool for physicians in their choice to optimize the treatment of FLA infections.

The type 2 statins, cerivastatin, rosuvastatin and pitavastatin eliminate Naegleria fowleri at low concentrations and by induction of programmed cell death (PCD)

Primary Amoebic Encephalitis due to Naegleria fowleri species is a fatal infection of the Central Nervous System mostly affecting children and young adults. Infections often occur after performance of risk activities in aquatic habitats such as swimming and splashing. PAḾs therapy remain a key issue to be solved which needs an urgent development. Recently, statins have been highlighted as possible novel compounds to treat PAM. Furthermore, type 2 statins due to improved pharmacological properties and lower toxicity could be use in the future. In the present work, three type 2 statins were checked for their activity against two type strains of N. fowleri. In addition, the effects at the cellular level triggered in treated amoebae were checked in order to evaluate if programmed cell death was induced. The obtained results showed that the tested statins, rosuvastatin, pitavastatin and cerivastatin were able to eliminate N. fowleri trophozoites and also induced PCD. Therefore, type 2 statins could be used in the near future for the treatment of PAM.

Laurinterol from Laurencia johnstonii eliminates Naegleria fowleri triggering PCD by inhibition of ATPases

Primary amoebic encephalitis (PAM) is a lethal disease caused by the opportunistic pathogen, Naegleria fowleri. This amoebic species is able to live freely in warm aquatic habitats and to infect children and young adults when they perform risk activities in these water bodies such as swimming or splashing. Besides the need to increase awareness of PAM which will allow an early diagnosis, the development of fully effective therapeutic agents is needed. Current treatment options are amphotericin B and miltefosine which are not fully effective and also present toxicity issues. In this study, the in vitro activity of various sesquiterpenes isolated from the red alga Laurencia johnstonii were tested against the trophozoite stage of a strain of Naegleria fowleri. Moreover, the induced effects (apoptotic cell death) of the most active compound, laurinterol (1), was evaluated by measuring DNA condensation, damages at the mitochondrial level, cell membrane disruption and production of reactive oxygen species (ROS). The obtained results demonstrated that laurinterol was able to eliminate the amoebae at concentrations of 13.42 ± 2.57 µM and also to induced programmed cell death (PCD) in the treated amoebae. Moreover, since ATP levels were highly affected and laurinterol has been previously reported as an inhibitor of the Na⁺/K⁺-ATPase sodium–potassium ion pump, comparison with known inhibitors of ATPases were carried out. Our results points out that laurinterol was able to inhibit ENA ATPase pump at concentrations 100 times lower than furosemide.

Understanding the true burden of "Naegleria fowleri" (Vahlkampfiidae) in patients from Northern states of India: Source tracking and significance

The present study is an attempt to investigate the presence of Naegleria fowleri in Indian population. A total of 307 patients were enrolled and water samples were collected from both residential and surrounding areas of patients found positive for N. fowleri. The different species of Naegleria from both clinical and water samples were identified taxonomically. Recommended microbiological conventional techniques were used to identify different Naegleria stages and other free-living amoebae from the samples. PCR assays, using both genus and species specific primers were also optimized. None of the samples were positive by conventional microbiological examinations. However, PCR assays detected only three samples positive for N. fowleri. A total of 10 water bodies (ponds), that were used by Naegleria positive patients were examined. The pH and temperature of the water samples collected from water bodies ranged between 5.6-7.2 and 25-32 °C respectively. Among all the 10 water samples tested, four samples were positive for genus Naegleria by PCR assay, of which only two samples, showed positive amplification for N. fowleri. The sequence analysis of N. fowleri strain belonged to genotype II.

Cerebrospinal fluid cytology in nonmalignant aseptic meningeal disorders

Cerebrospinal fluid cytology examination is a common and reliable primary and/or complementary procedure for the diagnosis of central nervous system (CNS) disorders. This review provides an update of aseptic meningeal disorders that may be encountered in cytopathology practice. The article covers the cytological findings and helpful ancillary studies needed of nonmalignant aseptic CNS disorders such as viral, bacterial, fungal and parasitic infections, and other noninfectious diseases, such as Mollaret's meningitis (recurrent benign lymphocytic meningitis), Guillain-Barré syndrome, multiple Sclerosis, subarachnoid haemorrhage, and drug-induced disorders.

Primary amoebic meningoencephalitis in North Queensland: the paediatric experience

Primary amoebic meningoencephalitis (PAM) is a fulminant, diffuse haemorrhagic meningoencephalitis caused by Naegleria fowleri, with an almost invariably fatal outcome. In Australia and the developed world, PAM remains a rare disease, although it is very likely that large numbers of cases go undetected in developing countries. N. fowleri is a thermophilic, free-living amoeba with a worldwide distribution. It is acquired when contaminated fresh water is flushed into the nose and penetrates the central nervous system via the cribriform plate. Clinical features are similar to those of bacterial meningitis, but it does not respond to standard therapy and rapid progression to death occurs in most cases. Some survivors have been reported; these patients received early treatment with amphotericin B in combination with a variety of other medications. Our review describes the local and worldwide experience of this disease and its clinical features, and discusses the associated diagnostic challenges. We hope that by detailing the local response to a recent case, and the outcomes of our public health campaign, we can improve the knowledge of this rare disease for doctors working in rural and remote Australia.

Naegleria fowleri after 50 years: is it a neglected pathogen?

It has been 50 years since the first case of primary amoebic meningoencephalitis (PAM), an acute and rapidly fatal disease of the central nervous system (CNS), was reported in Australia. It is now known that the aetiological agent of PAM is Naegleria fowleri, an amoeba that is commonly known as 'the brain-eating amoeba'. N. fowleri infects humans of different ages who are in contact with water contaminated with this micro-organism. N. fowleri is distributed worldwide and is found growing in bodies of freshwater in tropical and subtropical environments. The number of PAM cases has recently increased, and the rate of recovery from PAM has been estimated at only 5 %. Amphotericin B has been used to treat patients with PAM. However, it is important to note that there is no specific treatment for PAM. Moreover, this amoeba is considered a neglected micro-organism. Researchers have exerted great effort to design effective drugs to treat PAM and to understand the pathogenesis of PAM over the past 50 years, such as its pathology, molecular and cellular biology, diagnosis and prevention, and its biological implications, including its pathogenic genotypes, its distribution and its ecology. Given the rapid progression of PAM and its high mortality rate, it is important that investigations continue and that researchers collaborate to gain better understanding of the pathogenesis of this disease and, consequently, to improve the diagnosis and treatment of this devastating infection of the CNS.

Prevalence of Naegleria fowleri in Environmental Samples from Northern Part of India

Naegleria fowleri the causative agent of Primary Amoebic Meningoencephalitis, is ubiquitously distributed worldwide in various warm aquatic environments and soil habitats. The present study reports on the presence of Naegleria spp. in various water bodies present in Rohtak and Jhajjar district, of state Haryana, India. A total of 107 water reservoirs were screened from summer till autumn (2012 and 2013). In order to isolate Naegleria spp. from the collected water samples, the water samples were filtered and the trapped debris after processing were transferred to non-nutrient agar plates already seeded with lawn culture of Escherichia coli. Out of total 107 water samples, 43 (40%) samples were positive by culture for free living amoeba after incubation for 14 days at 37°C. To identify the isolates, the ITS1, 5.8SrDNA and ITS2 regions were targeted for PCR assay. Out of total 43 positive samples, 37 isolates were positive for Naegleria spp. using genus specific primers and the most frequently isolated species was Naegleria australiensis. Out of 37 Naegleria spp. positive isolates, 1 isolate was positive for Naegleria fowleri. The sequence analysis revealed that the Naegleria fowleri strain belonged to Type 2.