Transmission characteristics and prevention measures of Naegleria fowleri： a review / 上海预防医学

Objective To review the Naegleria fowleri and primary amoebic meningoencephalitis caused by the naegleria fowleri， so as to strengthen the public awareness of the disease and its prevention. Methods We reviewed the literatures and reports， and summarized the following information： epidemic status， life cycle and characteristics， environmental distribution and infection routes， pathogenesis and clinical manifestations， diagnosis and treatment， prevention and control measures. Results Primary amoeba meningoencephalitis is a water-borne disease caused by the Naegleria fowleri， which enters human body through the nose and arrives at the central nervous system through olfactory nerve， leading to hemorrhagic and necrotic meningitis. Although the disease is rare， it has a fatality rate of 95%. Most of the patients reported were healthy children or young adults who had nasal contact with water contaminated with Naegleria fowleri a week before symptoms appeared. At present， its pathology can be divided into contact mechanism and non-contact mechanism. In contact mechanism， the Naegleria fowleri relies on the phagocytosis of food cup on its surface and the release of cytolytic molecules that directly destroy host cells. In non-contact mechanism， the Naegleria fowleri has toxic effects by secreting proteins. The clinical symptoms are episodic， with an average time of five days from illness to death. At beginning， the symptoms may include headache， vomiting， fever and other influenza-like symptoms， followed by central nervous system symptoms， such as stiff neck， drowsiness， anorexia， fear and so on. Intravenous or intrathecal injection of amphotericin B is considered to be the basic treatment of this disease， which can be combined with other adjunct therapies such as ventricular shunt and cooling to reduce encephaledema. Conclusion Primary amoebic meningoencephalitis is a rare but highly fatal disease. We should strengthen the public awareness of the disease and its prevention， especially to avoid nasal contact with contaminated water. We should also strengthen scientific research， improve the level of diagnosis， and develop effective drugs to prevent the disease before it happens.

Primary amoebic meningoencephalitis in children: a case report and literature review / 中华实用儿科临床杂志

A case of primary amoebic meningoencephalitis (PAM) treated in the First Affiliated Hospital of Xinxiang Medical University in March 6, 2022 was reported.The proband was a 14-year-old boy, who was admitted to the hospital because of " fever, headache and vomiting for 2 days" . Metagenomic next-generation sequencing (mNGS) was consequently conducted to examine the pathogens in cerebrospinal fluid.Naegleria infection was detected, so the child was diagnosed with PAM.The disease developed rapidly, and the patient died 29 hours after admission.In the paper, a total of 13 studies were reviewed, and 15 children with PAM were reported.Of the reported cases, only 1 case survived, 14 cases died.PAM had a low incidence, a dangerous condition, and high mortality.Most cases were diagnosed by autopsy or pathogen diagnosis in cerebrospinal fluid.This case is confirmed by mNGS of pathogens, and it is rarely reported at home and abroad.

Various brain-eating amoebae: the protozoa, the pathogenesis, and the disease / 医学前沿

Among various genera of free-living amoebae prevalent in nature, some members are identified as causative agents of human encephalitis, in which Naegleria fowleri followed by Acanthamoeba spp. and Balamuthia mandrillaris have been successively discovered. As the three dominant genera responsible for infections, Acanthamoeba and Balamuthia work as opportunistic pathogens of granulomatous amoebic encephalitis in immunocompetent and immunocompromised individuals, whereas Naegleria induces primary amoebic meningoencephalitis mostly in healthy children and young adults as a more violent and deadly disease. Due to the lack of typical symptoms and laboratory findings, all these amoebic encephalitic diseases are difficult to diagnose. Considering that subsequent therapies are also affected, all these brain infections cause significant mortality worldwide, with more than 90% of the cases being fatal. Along with global warming and population explosion, expanding areas of human and amoebae activity in some regions lead to increased contact, resulting in more serious infections and drawing increased public attention. In this review, we summarize the present information of these pathogenic free-living amoebae, including their phylogeny, classification, biology, and ecology. The mechanisms of pathogenesis, immunology, pathophysiology, clinical manifestations, epidemiology, diagnosis, and therapies are also discussed.

Occurrence of The Pathogenic Amoeba Naegleria fowleri, Pathogenesis, Diagnosis, and Treatment Options

@#Naegleria fowleri is the causative agent of primary amoebic meningoencephalitis (PAM) that infects the central nervous system (CNS). The amoeba is present ubiquitously. The infection is rare but has a high mortality rate. The pathogenic amoeba reaches the host through the nasal passage and migrates along the olfactory nerves to reach the human brain and cause severe destruction of the CNS. As Malaysia has a large population that practising ablutions in daily routine, the risk of infection increases. Two mechanisms associated with the infection include contact-dependent and contact-independent. Signs and symptoms vary from early stage to later stage of infection. CSF and brain biopsy are the common specimens collected used to diagnose the PAM infection and usually detect and identify by PCR method. As for treatment, the CDC of United States America has recommended the usage of miltefosine that provides promising in vitro therapy against N. fowleri. This review will discuss more on the occurrence of N. fowleri, pathogenicity, diagnostic tools, and pharmacotherapy approach against N. fowleri infection.

Primary amoebic meningoencephalitis in an infant

Primary amoebic meningoencephalitis is rare but fatal disease encountered in immunocompetent individuals. Here, we present a case of a previously healthy 8-month-old female child, who presented with features of meningoencephalitis of 2 days' duration. Rapidly moving trophozoites of amoeba were observed in cerebrospinal fluid, which were confirmed to be Naegleria fowleri on polymerase chain reaction. Broad-spectrum antimicrobial therapy with ceftriaxone, vancomycin, amphotericin B and acyclovir was initiated. However, the patient deteriorated and left the hospital against medical advice. The isolation of N. fowleri in this case demands for increased awareness for prompt diagnosis and management in view of its high mortality.

Demostración del ameboflagelado Naegleria fowleri como agente etiológico de meningoencefalitis amébica primaria en Santiago de Cuba / Demonstration of flagellum ameba Naegleria fowleri as etiological agent of primary amebic meningoencephalitis in Santiago de Cuba

En los últimos años se ha demostrado que el amebo-flagelado Naegleria fowleri es el causante de la meningoencefalitis amébica primaria (MEAP). En Cuba ha sido mencionada la sospecha de su presencia en un líquido céfalo-raquídeo (LCR) de una ameba cuya locomoción y circunstancias sugería que pudiera ser esta ameba. Se realizó el análisis en fresco y en cultivo, con Test de Flagelación de 64 muestras de LCR seleccionadas al azar a partir de las 173 que presentaron las características de transparencia y negatividad a bacterias, requisitos iniciales en búsqueda de este agente, partiendo de una muestra inicial de 1 488 muestras de LCR procedentes de pacientes con meningoencefalitis clínicamente establecidas. De estos 64 LCR, 2 resultaron positivos a la evaluación por los diferentes métodos lo que permitió teñirlos con Giemsa, demostrar su capacidad de flagelación y su resistencia a TMT. Las características citoquímicas de los líquidos concordaban con lo planteado en la literatura y uno de los pacientes sobrevivió, el otro falleció. La patogenicidad de los ameboflagelados aislados de esas dos muestras de LCR se comprobó en el modelo animal ratón albino suizo y fueron observados al microscopio electrónico. Lo anterior confirma microbiológicamente por primera vez en el país este agente etiológico, aunque ya había elementos clínicos y de laboratorio de sospecha en casos anteriores

During the last years it has been demonstrated that the flagellae-carring ameba Naegleria fowleri is the aethiologic agent of the primary amoebic meningoencephalitis (PAME), in Cuba the suspicion of its presence has been mentioned in a Cefalo Raquideal Fluid (CRF) of an ameba whose locomotion and circumstances suggested that it could be this organism. The present work carries out the analysis in fresh CRF samples and after culture, performing the Flagelation Test of the 64 CRF that presented the characteristics of transparency and negativity to bacterial culture ,needed to suspicion of this flagellae-carring ameba, leaving of an starting sample of 1488 CRF.From this analysed sample of CRF only two were positive to the observation of amebas what allowed to tint them with Giemsa and also with Lugol, to demonstrate their flagelation capacity and their resistance to TMT in the corresponding test. The citochemical characteristics of the liquids agreed with that outlined in the literature for this organisms,and one of the patients survived, the other one died. The patogenicity of the isolated flagellae-carring amebas was proven in the animal model of Swiss albino mouse and both isolated strains were observed by the electronic microscope. This results are the basis for considering the present report the first one confirming N.Fowleri as aetiologic agent in two cases of PAME in Cuba

Survey of naegleria fowleri the causative agent of Primary Amoebic Meningoencephalitis (PAM) in stagnant waters around factory area in Thailand.

Naegleria fowleri a free-living amoeba commonly found in moist soil and fresh water, enters the body via the nasal mucosa and migrates along the olfactory nerve to the brain, where it causes fulminant meningoencephalitis that is generally fatal. From 1988 to 1992, a survey of pathogenic Naegleria sp. was carried out in the industrial areas of three provinces. Water samples from warm and fresh ponds were collected from Pathumthani (34 samples), Samutprakan (150 samples) and Lopburi (162 samples). AII specimens were cultured in non-nutrient agar Escherichia coli media (NNE) AT 37oC. The amoebae obtained from water samples were in amoeboid, flagellate and cyst form. The amoeboflagellate transformation was occurred in distilled water and amoebae saline. The amoebae from water samples in Pathumthain (70.59 per cent) and Samutprakan (69.30 per cent) were cultured in Chang’s axenic media (SCGYEM) at 37oC. Non-pathogenic and pathogenic Naeglenia sp were distinguished by the characteristics of growth properties since the pathogenic form can grow only in the SCGYEM axenic media. The percentage of amoebae from Pathumthani and Samutprakan in SCGYEM axenic media at 37oC. were 11.46% and 12.00% respectively. The amoebae from Lopburi cultured in NNE 45oC (10.49 per cent) was inoculated through nasal cavity of Rattus rattus. The result was 10.49 per cent of the amoebae also determined for the virulence and the rats were died in 5-7 days. The histological studies of mouse brain tissue sections revealed the large central karysome and halo around the nucleus of the organisms, the amount of amoebae were accumulated around perivascular space. The characteristics, pathogenicity and pathology of pathogenic Naegleria sp. are the same as Naegleria fowleri.