Successful Treatment of Confirmed Naegleria fowleri Primary Amebic Meningoencephalitis

Primary amebic meningoencephalitis caused by Naegleria fowleri is a rare but nearly always fatal parasitic infection of the brain. Globally, few survivors have been reported, and the disease has no specific treatment. We report a confirmed case in Pakistan in a 22-year-old man who survived after aggressive therapy.

Metagenomic next-generation sequencing for diagnosis of fatal Balamuthia amoebic encephalitis

INTRODUCTION

Balamuthia amoebic encephalitis (BAE), caused by Balamuthia mandrillaris, is a rare and life-threatening infectious disease with no specific and effective treatments available. The diagnosis of BAE at an early stage is difficult because of the non-specific clinical manifestations and neuroimaging.

CASE DESCRIPTION

A 52-year-old male patient, who had no previous history of skin lesions, presented to the emergency department with an acute headache, walking difficulties, and disturbance of consciousness. The patient underwent a series of examinations, including regular cerebrospinal fluid (CSF) studies and magnetic resonance imaging, and tuberculous meningoencephalitis was suspected. Despite being treated with anti-TB drugs, no clinical improvement was observed in the patient. Following corticosteroid therapy, the patient developed a rapid deterioration in consciousness with dilated pupils. Metagenomic next-generation sequencing (mNGS) revealed an unexpected central nervous system (CNS) amoebic infection, and the patient died soon after the confirmed diagnosis.

CONCLUSION

This study highlights the application of mNGS for the diagnosis of patients with suspected encephalitis or meningitis, especially those caused by rare opportunistic infections.

Unexpected trends of amoebic encephalitis in Pakistan

Annual reported cases of Naegleria fowleri (NF), popularly known as brain eating amoeba, are becoming a huge challenge for Pakistani health authorities. Karachi has seen cases regularly up till the present but Lahore has not. The spread of this amoeba in non-chlorinated water is a major concern for the authorities. NF is an amoeba commonly found in warm freshwater environments such as lakes, hot springs and poorly chlorinated swimming pools. It poses a significant risk during hot weather when water-related recreational activities are popular. Where there is a non-chlorinated water supply, its spread is aggravated.

Naegleria fowleri in 2023: A rising threat to Pakistan

Madam, Naegleria fowleri, i.e., brain-eating amoeba, is a single-cell, free-living parasite that resides in soil and warm freshwater bodies such as lakes, rivers, and hot springs. It enters the nasal cavity from contaminated water, uses the olfactory nerve to reach the brain, and causes a deadly infection called primary amoebic meningoencephalitis (PAM), with a mortality rate higher than 97% even with treatment. (1,2) It causes symptoms similar to those of other bacterial and viral meningitis, such as fever, headache, vomiting, altered level of consciousness and coma, followed by death in the span of a week to 10 days. (1)  There are 20 strains of Naegleria world worldwide, but only N. fowleri is dangerous to humans. (1) In 2008, the first case was reported from Karachi, Pakistan. (2) By 2019, the number had reached 146, (2) and the cases have been increasing until now. In 2023, eight cases have been reported from May to August, among which seven are from the province of Sindh and one from Punjab. (3, 4, 6) The available data shows that two deaths were due to recreational water activities and others because of contaminated tap water.(3,4) This pathogenic amoeba commonly infects men, and the majority of cases were in people aged 26 to 45 years.(1) Of all the reported cases this year, one was a 32-year-old female, and seven were males in the aged  19-45 years.(3,4, 6) The increasing global warming and higher authorities’ negligence towards WHO recommended chlorination (0.1-10 mg/L) of domestic water supply are contributing factors to the higher burden of Naegleria fowleri cases in Karachi, the largest metropolitan city of Pakistan .(5) The new lethal strain of N. fowleri, named as Karachi-NF001, has been found in one patient who traveled from Saudi Arabia to Karachi in 2019. (2) These emerging cases concern strict actions against this problem and the need to alert the Karachi Water and Sewerage Board (KWSB) regarding consistent chlorination from April to October. (5) The monsoon season (May to September) is the best time to spread awareness regarding its prevention and update the current status of N. fowleri in our country. The general public should be encouraged to use boiled or sterilised water for ablution and avoid aquatic activities in non-chlorinated water during the summer season. (3) Besides that, all underground and overhead water tanks in homes, hospitals, shopping malls, schools, offices, etc. should be cleaned once a year. (3)

Case Report: A Series of Three Meningoencephalitis Cases Caused by Acanthamoeba spp. from Eastern India

Acanthamoeba spp. are rare etiological agents of meningoencephalitis with high mortality. We present three cases of Acanthamoeba meningoencephalitis in immunocompetent individuals from Eastern India. The first patient presented with fever and headache; the second with headache, visual disturbance, and squint; and the third presented in a drowsy state. The cases presented on March 3, 18, and 21, 2023 respectively. The first two patients had concomitant tubercular meningitis for which they received antitubercular therapy and steroid. Their cerebrospinal fluid showed slight lymphocytic pleocytosis and increased protein. The diagnosis was done by microscopy, culture, and polymerase chain reaction. They received a combination therapy comprising rifampicin, fluconazole, and trimethoprim-sulfamethoxazole. The first patient additionally received miltefosine. She responded well to therapy and survived, but the other two patients died despite intensive care. Detection of three cases within a period of 1 month from Eastern India is unusual. It is imperative to sensitize healthcare providers about Acanthamoeba meningoencephalitis to facilitate timely diagnosis and treatment of the disease.

Balamuthia mandrillaris amoebic encephalitis mimicking tuberculous meningitis

A 76-year-old female with no apparent immunosuppressive conditions and no history of exposure to freshwater and international travel presented with headache and nausea 3 weeks before the presentation. On admission, her consciousness was E4V4V6. Cerebrospinal fluid analysis showed pleocytosis with mononuclear cell predominance, elevated protein, and decreased glucose. Despite antibiotic and antiviral therapy, her consciousness and neck stiffness gradually worsened, right eye-movement restriction appeared, and the right direct light reflex became absent. Brain magnetic resonance imaging revealed hydrocephalus in the inferior horn of the left lateral ventricle and meningeal enhancement around the brainstem and cerebellum. Tuberculous meningitis was suspected, and pyrazinamide, ethambutol, rifampicin, isoniazid, and dexamethasone were started. In addition, endoscopic biopsy was performed from the white matter around the inferior horn of the left lateral ventricle to exclude brain tumor. A brain biopsy specimen revealed eosinophilic round cytoplasm with vacuoles around blood vessels, and we diagnosed with amoebic encephalitis. We started azithromycin, flucytosine, rifampicin, and fluconazole, but her symptoms did not improve. She died 42 days after admission. In autopsy, the brain had not retained its structure due to autolysis. Hematoxylin and eosin staining of her brain biopsy specimen showed numerous amoebic cysts in the perivascular brain tissue. Analysis of the 16S ribosomal RNA region of amoebas from brain biopsy and autopsy specimens revealed a sequence consistent with Balamuthia mandrillaris. Amoebic meningoencephalitis can present with features characteristic of tuberculous meningitis, such as cranial nerve palsies, hydrocephalus, and basal meningeal enhancement. Difficulties in diagnosing amoebic meningoencephalitis are attributed to the following factors: (1) excluding tuberculous meningitis by microbial testing is difficult, (2) amoebic meningoencephalitis has low incidence and can occur without obvious exposure history, (3) invasive brain biopsy is essential in diagnosing amoebic meningoencephalitis. We should recognize the possibility of amoebic meningoencephalitis when evidence of tuberculosis meningitis cannot be demonstrated.

Primary amebic meningoencephalitis: a review of Naegleria fowleri and analysis of successfully treated cases

Primary amebic meningoencephalitis (PAM) is a necrotizing and hemorrhagic inflammation of the brain and meninges caused by Naegleria fowleri, a free-living thermophilic ameba of freshwater systems. PAM remains a neglected disease that disproportionately affects children in tropical and subtropical climates, with an estimated mortality rate of 95-98%. Due to anthropogenic climate change, the average temperature in the USA has increased by 0.72 to 1.06 °C in the last century, promoting the poleward spread of N. fowleri. PAM is often misdiagnosed as bacterial meningitis or viral encephalitis, which shortens the window for potentially life-saving treatment. Diagnosis relies on the patient's history of freshwater exposure and the physician's high index of suspicion, supported by cerebrospinal fluid studies. While no experimental trials have been conducted to assess the relative efficacy of treatment regimens, anti-amebic therapy with adjunctive neuroprotection is standard treatment in the USA. We performed a literature review and identified five patients from North America between 1962 and 2022 who survived PAM with various degrees of sequelae.

High-Throughput Screen of Microbial Metabolites Identifies F1FO ATP Synthase Inhibitors as New Leads for Naegleria fowleri Infection

Primary amebic meningoencephalitis (PAM), a brain infection caused by a free-living ameba Naegleria fowleri, leads to an extensive inflammation of the brain and death within 1-18 (median 5) days after symptoms begin. Although natural products have played a significant role in the development of drugs for over a century, research focusing on identifying new natural product-based anti-N. fowleri agents is limited. We undertook a large-scale ATP bioluminescence-based screen of about 10,000 unique marine microbial metabolite mixtures against the trophozoites of N. fowleri. Our screen identified about 100 test materials with >90% inhibition at 50 μg/mL and a dose-response study found 20 of these active test materials exhibiting an EC50 ranging from 0.2 to 2 μg/mL. Examination of four of these potent metabolite mixtures, derived from our actinomycete strains CNT671, CNT756, and CNH301, resulted in the isolation of a pure metabolite identified as oligomycin D. Oligomycin D exhibited nanomolar potency on multiple genotypes of N. fowleri, and it was five- or 850-times more potent than the recommended drugs amphotericin B or miltefosine. Oligomycin D is fast-acting and reached its EC50 in 10 h, and it was also able to inhibit the invasiveness of N. fowleri significantly when tested on a matrigel invasion assay. Since oligomycin is known to manifest inhibitory activity against F1FO ATP synthase, we tested different F1FO ATP synthase inhibitors and identified a natural peptide leucinostatin as a fast-acting amebicidal compound with nanomolar potency on multiple strains.

Clinical manifestations and outcome of patients with primary amoebic meningoencephalitis in Pakistan. A single-center experience

Primary amoebic meningoencephalitis (PAM) is a rapidly progressing central nervous system (CNS) infection caused by Naegleria fowleri, a free-living amoeba found in warm freshwater. The disease progression is very rapid, and the outcome is nearly always fatal. We aim to describe the disease course in patients admitted with PAM in a tertiary care center in Karachi, Pakistan between the periods of 2010 to 2021. A total of 39 patients were included in the study, 33 males (84.6%). The median age of the patients was 34 years. The most frequent presenting complaint was fever, which was found in 37 patients (94.9%) followed by headache in 28 patients (71.8%), nausea and vomiting in 27 patients (69.2%), and seizures in 10 patients (25.6%). Overall, 39 patients underwent lumbar puncture, 27 patients (69.2%) had a positive motile trophozoites on CSF wet preparation microscopy, 18 patients (46.2%) had a positive culture, and 10 patients had a positive PCR. CSF analysis resembled bacterial meningitis with elevated white blood cell counts with predominantly neutrophils (median, 3000 [range, 1350-7500] cells/μL), low glucose levels median, 14 [range, 1-92] mg/dL), and elevated protein levels (median, 344 [range, 289-405] mg/dL). Imaging results were abnormal in approximately three-fourths of the patients which included cerebral edema (66.7%), hydrocephalus (25.6%), and cerebral infarctions (12.8%). Only one patient survived. PAM is a fatal illness with limited treatment success. Early diagnosis and prompt initiation of treatment can improve the survival of the patients and reduce mortality.

Naegleria fowleri outbreak in Pakistan: unveiling the crisis and path to recovery

The outbreak of Naegleria fowleri in Pakistan presents a significant public health concern due to its high fatality rate and limited treatment options. This review explores the impact of the outbreak on communities and the challenges faced in combating the disease. It evaluates available treatment options and highlights the need for early diagnosis and intervention. The study proposes recommendations to improve public health preparedness, including public awareness campaigns, enhanced healthcare infrastructure, and robust water surveillance systems. Collaboration between research institutions and public health organizations is emphasized to develop effective outbreak response strategies.

A primary amoebic meningoencephalitis case associated with swimming in seawater

This case report describes a 62-year-old male fisherman who presented with persistent vomiting, headache, and behavior changes. Despite initial antibiotic and corticosteroid treatment, his condition worsened, leading to coma and subsequent death. Macro-genome sequencing of cerebrospinal fluid (CSF) revealed the presence of Naegleria fowleri infection, which had been missed during initial laboratory tests. The patient's exposure history included sea-swimming near Zhoushan Island.

Fatal Primary Amebic Meningoencephalitis due to Naegleria fowleri: The First Imported Case in Korea

Primary amebic meningoencephalitis (PAM) is a rare, but almost always fatal, central nervous system infection caused by Naegleria fowleri, which are thermophilic free-living amoeba. Here, we report the first case of PAM detected in South Korea, probably imported from Thailand. Despite antimicrobial treatment for N. fowleri infection with a combination of intravenous liposomal amphotericin B, fluconazole, azithromycin, and oral rifampin, the patient died 13 days after the onset of symptoms. Clinicians in South Korea treating severe meningoencephalitis, especially in individuals returning from tropical areas, are encouraged to include PAM in the differential diagnoses, given the accelerated global warming and increased overseas trips.

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.

Clinical Reasoning: A 67-Year-Old Man With Multiple Intracranial Lesions

A wide variety of diseases present with intracranial lesions. In this case report, a 67-year-old man initially presented to an outside hospital with nausea, headache, and ataxia and was found to have multiple intracranial lesions. Diagnostic workup was ultimately unrevealing, and his condition improved after a course of steroids and antibiotics. Unfortunately, symptoms returned 3 months later. MRI of the brain revealed progression of his intracranial lesions. This case highlights a diagnostic approach and general management strategy for patients presenting with undifferentiated intracranial pathology. A final diagnosis is ultimately reached and raises further discussion.

Fatal Primary Amebic Meningoencephalitis in Nebraska: Case Report and Environmental Investigation, August 2022

Primary amebic meningoencephalitis (PAM) is a rare and lethal infection caused by Naegleria fowleri. We report an epidemiological and environmental investigation relating to a case of PAM in a previously healthy boy age 8 years. An interview of the patient's family was conducted to determine the likely exposure site and to assess risk factors. Data from the United States Geological Survey site at Waterloo, NE, on the Elkhorn River were used to estimate water temperature and streamflow at the time and site of exposure. Data from the National Weather Service were used to estimate precipitation and ambient air temperature at the time and site of exposure. Despite conventional treatment, the patient died 2 days after hospital admission. The patient participated in recreational water activities in the Elkhorn River in northeastern Nebraska 5 days before symptom onset. In the week before exposure, water and ambient air high temperatures reached annual highs, averaging 32.4°C and 35.8°C, respectively. The day before infection, 2.2 cm of precipitation was reported. Streamflow was low (407 ft3/s). Infections in several northern states, including Nebraska, suggest an expanding geographic range of N. fowleri transmission, which may lead to increased incidence of PAM in the United States. Similar environmental investigations at suspected exposure sites of future cases will allow data aggregation, enabling investigators to correlate environmental factors with infection risk accurately.

Amebic encephalitis and meningoencephalitis: an update on epidemiology, diagnostic methods, and treatment

PURPOSE OF REVIEW

Free-living amebae (FLA) including Naegleria fowleri , Balamuthia mandrillaris , and Acanthamoeba species can cause rare, yet severe infections that are nearly always fatal. This review describes recent developments in epidemiology, diagnosis, and treatment of amebic meningoencephalitis.

RECENT FINDINGS

Despite similarities among the three pathogenic FLA, there are notable variations in disease presentations, routes of transmission, populations at risk, and outcomes for each. Recently, molecular diagnostic tools have been used to diagnose a greater number of FLA infections. Treatment regimens for FLA have historically relied on survivor reports; more data is needed about novel treatments, including nitroxoline.

SUMMARY

Research to identify new drugs and guide treatment regimens for amebic meningoencephalitis is lacking. However, improved diagnostic capabilities may lead to earlier diagnoses, allowing earlier treatment initiation and improved outcomes. Public health practitioners should continue to prioritize increasing awareness and providing education to clinicians, laboratorians, and the public about amebic infections.

Acanthamoeba meningoencephalitis causing secondary hemophagocytic lymphohistiocytosis in an immunocompetent patient: A first case report

Acanthamoeba is a rare cause of granulomatous amoebic encephalitis (GAE) associated with high mortality. There have been few case reports of Acanthamoeba meningoencephalitis worldwide. Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory condition caused by abnormally active macrophages and cytotoxic T lymphocytes; its secondary form is due to infections or malignancies. However, HLH is rather an unknown complication of GAE. We describe an unusual and previously unreported case of Acanthamoeba meningoencephalitis in a young immunocompetent female culminating in secondary HLH.

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.

Primary Amoebic Meningoencephalitis by Naegleria fowleri: Pathogenesis and Treatments

Naegleria fowleri is a free-living amoeba (FLA) that is commonly known as the "brain-eating amoeba." This parasite can invade the central nervous system (CNS), causing an acute and fulminating infection known as primary amoebic meningoencephalitis (PAM). Even though PAM is characterized by low morbidity, it has shown a mortality rate of 98%, usually causing death in less than two weeks after the initial exposure. This review summarizes the most recent information about N. fowleri, its pathogenic molecular mechanisms, and the neuropathological processes implicated. Additionally, this review includes the main therapeutic strategies described in case reports and preclinical studies, including the possible use of immunomodulatory agents to decrease neurological damage.

Angiostrongylus cantonensis Infection of Central Nervous System, Guiana Shield

We report a case of eosinophilic meningitis complicated by transverse myelitis caused by Angiostrongylus cantonensis in a 10-year-old boy from Brazil who had traveled to Suriname. We confirmed diagnosis by serology and real-time PCR in the cerebrospinal fluid. The medical community should be aware of angiostrongyliasis in the Guiana Shield.

Estimation of Undiagnosed Naegleria fowleri Primary Amebic Meningoencephalitis, United States1

Primary amebic meningoencephalitis is an acute, rare, typically fatal disease. We used epidemiologic risk factors and multiple cause-of-death mortality data to estimate the number of deaths that fit the typical pattern for primary amebic meningoencephalitis; we estimated an annual average of 16 deaths (8 male, 8 female) in the United States.

A case of Naegleria fowleri related primary amoebic meningoencephalitis in China diagnosed by next-generation sequencing

BACKGROUND

Primary amoebic meningoencephalitis (PAM), caused by Naegleria fowleri, is a rare protozoan infectious disease in China. A fatality rate of over 95% had been reported due to extremely rapid disease progression in the USA and other countries. Rapid and precise identification of the causative agent is very important to clinicians for guiding their choices for administering countermeasures in the clinic. In this report, we applied the next-generation sequencing (NGS) method to rapidly show that N. fowleri was the causative agent of a fatal case involving a 42-year-old man with severe PAM disease, the first reported in mainland China.

CASE PRESENTATION

A 42-year old male in a deep coma was admitted to Shenzhen Third People's Hospital, a special medical care unit with expertise in infectious diseases. Increased intracranial pressure was detected. The cerebrospinal fluid (CSF) sample was found to be red and cloudy with increased leukocyte and protein levels. While bacterial cultures with CSF were negative, N. fowleri was determined to be the causative agent with NGS. Amphotericin B (AmB), a drug with anti-amoeba activity, was used immediately, but the treatment came too late and the patient died 2 days after the NGS confirmation.

CONCLUSION

In this paper, we reported a case of PAM disease for the first time in mainland China. NGS was used for rapid diagnosis and provided guidance for prescribing medications. However, the patient died due to a late admission amid advanced PAM disease. Early detection of N. fowleri is necessary in order to select effective drug treatments and control the disease progression. Despite the negative survival outcome, NGS was shown to be a promising method of rapid and precise identification of N. fowleri.

Canine amoebic meningoencephalitis due to Balamuthia mandrillaris

A 1-year-old Siberian Husky dog with acute-onset of seizures, recumbency, paddling, and muscular fasciculations was autopsied. A locally extensive hemorrhagic and malacic focus was noted in the right cerebral frontal cortex, and severe necrotizing and hemorrhagic, neutrophilic meningoencephalitis was diagnosed microscopically. Amoebic trophozoites and cysts were identified within the affected cerebral parenchyma and confirmed by indirect immunofluorescence assay and real-time PCR as Balamuthia mandrillaris. B. mandrillaris is found in soil and water and the infection has been reported in both immunocompromised and immunocompetent humans and rarely in the dog.

Identification and molecular typing of Naegleria fowleri from a patient with primary amebic meningoencephalitis in China

Naegleria fowleri is the only Naegleria spp. known to cause an acute, fulminant, and rapidly fatal central nervous system infection in humans called primary amebic meningoencephalitis (PAM). In 2016, a patient with suspected PAM was found in Zhejiang Province of China. The pathogen was identified by microscopic examination and PCR. The positive PCR products were sequenced and the sequences were aligned using the NCBI BLAST program. The homologous and phylogenetic analysis was conducted using MEGA 6 program. On microscopy of direct smears, motile cells with pseudopodia were observed, and the motion characteristics of the pseudopodia as well as the cell morphology suggested that the pathogens were amoeba trophozoites. Wright-Giemsa-stained smears showed amoeba trophozoites of various shapes, which measured 10-25μm in size; these were characterized by a prominent, centrally placed nucleolus and a vacuolated cytoplasm. PCR was negative for Entamoeba histolytica and Entamoeba dispar, but positive for Naegleria spp. and N. fowleri. The nucleotide sequences acquired in this study have been submitted to GenBank with accession numbers KX909928 and KX909927, respectively. The BLAST analysis revealed that the sequences of KX909928 and KX909927 had 100% similarity with the sequence of the N. fowleri gene (KT375442.1). Sequence alignment and the phylogenetic tree revealed that the N. fowleri collected in this study was classified as genotype 2 and was most closely related to Naegleria lovaniensis. This study confirmed N. fowleri as the agent responsible for the infection in this patient. PAM normally progresses rapidly and is generally universally fatal within a week. Unfortunately this patient died at 2 weeks after the onset of symptoms.

Evaluation of Five Diagnostic Methods for the Detection and Quantification of Myxobolus Cerebralis

Diagnostic methods were used to identify and quantify Myxobolus cerebralis, a myxozoan parasite of salmonid fish. In this study, 7-week-old, pathogen-free rainbow trout ( Oncorhynchus mykiss) were experimentally infected with M. cerebralis and at 7 months postinfection were evaluated with 5 diagnostic assays: 1) pepsin–trypsin digest (PTD) to detect and enumerate spores found in cranial cartilage, 2) 2 different histopathology grading scales that provide a numerical score for severity of microscopic lesions in the head, 3) a conventional single-round polymerase chain reaction (PCR), 4) a nested PCR assay, and 5) a newly developed quantitative real-time TaqMan PCR. There were no significant differences ( P > 0.05) among the 5 diagnostic assays in distinguishing between experimentally infected and uninfected control fish. The 2 histopathology grading scales were highly correlated ( P < 0.001) for assessment of microscopic lesion severity. Quantification of parasite levels in cranial tissues using PTD and real-time TaqMan PCR was significantly correlated r = 0.540 ( P < 0.001). Lastly, 104 copies of the 18S rDNA gene are present in the M. cerebralis genome, a feature that makes this gene an excellent target for PCR-based diagnostic assays. Also, 2 copies of the insulin growth factor–I gene are found in the rainbow trout genome, whose detection can serve both as an internal quality control for amplifiable DNA and as a basis to quantify pathogen genome equivalents present in quantitative PCR assays.

Comparison of the clinical presentations of Naegleria fowleri primary amoebic meningoencephalitis with pneumococcal meningitis: a case-control study

BACKGROUND

Primary amoebic meningoencephalitis (PAM) is a rare but fatal infection caused by Naegleria fowleri. The infection is acquired by deep nasal irrigation with infected water. Patients present with signs and symptoms similar to pneumococcal meningitis, leading to delayed diagnosis and treatment and hence high mortality.

METHODS

We conducted a case-control study comparing culture proven cases of PAM with pneumococcal meningitis presenting to our center between April 2008 and September 2014. Only patients with blood and/or cerebrospinal fluid cultures positive for Streptococcus pneumoniae during the same time period were included for comparison.

RESULTS

There were 19 cases of PAM and pneumococcal meningitis, each. When comparing PAM with pneumococcal meningitis, patients with PAM were more likely to be male (89.5 vs. 36.8 %), younger (mean age: 30 vs. 59 years), present with seizures (42.1 vs. 5.3 %). Both groups of patients presented with similar vital signs and there were no remarkable differences on physical examinations, Glasgow Coma Scale scores, laboratory and radiological investigations and cerebrospinal fluid parameters. PAM was also more likely to present if the city's average maximum temperature was higher in the previous week (mean: 34.6 vs. 30 °C). There was history of fresh water contact in only one patient. On multivariate analysis, PAM was more likely if patients presented when the city's average maximum temperature was high, being young males.

CONCLUSION

PAM and pneumococcal meningitis remain virtually indistinguishable; however, these predictive features should be validated in a prospective study and may lead to a viable algorithm for early management of these patients.

Fatal primary meningoencephalitis caused by Naegleria fowleri

Naegleria fowleri is a free living parasite which habitats in fresh water reservoirs. It causes a fatal nervous system infection known as primary amoebic meningoencephalitis by invading through cribriform plate of nose and gaining entry into brain. We report a case of primary amoebic meningoencephalitis caused by Naegleria fowleri in Karachi, Pakistan, in a 42 years old male poultry farm worker having no history of swimming. Clinical course was fulminant and death occurred within one week of hospital admission. Naegleria fowleri was detected by wet mount technique in the sample of cerebrospinal fluid collected by lumbar puncture of patient. This is a serious problem and requires immediate steps to prevent general population to get affected by this lethal neurological infection.

NAEGLARIA FOWLERI: THE BRAIN EATING AMOEBA OR AN ENIGMA?

Naeglaria fowleri (N. fowleri), popularly known as the brain eating amoeba is the causative agent of the fulminant disease, primary amoebic meningoencephalitis (PAM). Although a rare disease, it is a threat to human health with a case fatality rate ranging from 95-99%. PAM cases have been reported from the United States of America, Australia, Europe and Asia. From 1962 to 2014, 133 people have been infected by N. fowleri in the USA, out of which only three have survived. None of the PAM cases reported in Pakistan so far has survived. This underscores the importance to identify factors, which have led to the failure in decreasing case fatality associated with N. fowleri despite major advances in medical technology, health care; and prevention and control strategies since the first reported case in 1965. We need to focus on eliciting risk factors of the disease prevalent in our part of the world, which are at variance with the developed world. A predominant number. of PAM cases in the West are reported in young males who had participated in recreational activities. However, majority of cases reported in Pakistan are also among young males but they were linked with the religious practice of ablution. What is required to better understand and hence manage this enigma is further research. Further research is to be conducted to discover potent antimicrobials, to test the effectiveness of the new transcribial device in managing PAM, and to identify host factors, which make an individual susceptible to N. fowleri. Investigation of environmental factors related to N. fowleri also needs to be done. Doing so is of paramount importance, as it will help identify the preventive strategies to be employed against N. fowleri.

Primary Amoebic Meningoencephalitis

Primary amoebic meningoencephalitis due to free living amoeba, also called 'brain eating amoeba', Naegleria fowleri, was detected in retroviral disease patient of 40 years who has history of using well water. Patient was admitted with severe headache, fever intermittent, nausea, vomiting and slurring of speech. CT scan and MRI scan findings were normal. CSF examination showed increased protein, low sugar and predominant lymphocytes. CSF was negative for cryptococcal antigen but wet mount preparation showed highly motile free living amoeba Naegleria fowleri. Patient was put on Amphotericin B, Metronidazole, Rifampicin in addition to ART and ATT and other supportive medications. His headache was relieved and patient improved and was discharged on request. Earlier eight cases have been reported from India of which four cases survived the acute episode.

Neurotropic T-cell-rich B-cell lymphoma in a 14-year-old Morgan gelding

A 14-year-old Morgan gelding was presented for progressive weakness and muscle atrophy. The horse was initially diagnosed with equine protozoal myelitis based on history, physical examination, and laboratory diagnostics. Despite therapy, the horse declined clinically and was euthanized. Necropsy revealed a rare form of neurotropic lymphoma, described in this report.

Emerging trends in free-living amebic infections of the brain: implications for organ transplantation

This epidemiological review analyzed cases of Naegleria fowleri primary amebic meningoencephalitis (PAM) and Balamuthia mandrillaris granulomatous amebic encephalitis (GAE) for behavioral and demographic risk factors for pathogen exposures and potential transmission by organ transplantation. The Centers for Disease Control and Prevention (CDC) Naegleria Workgroup Registry provided 121 cases of laboratory-confirmed PAM over the period, 1937-2007. The CDC and the California Encephalitis Project provided 28 cases of GAE over the period, 1994-2010. There was a statistically significant increase in clusters of PAM cases between the periods, 1937-1996 and 1997-2007. Risk factors for PAM included male gender, freshwater exposures, summer exposures, and exposures in southern-tier US (United States) states. Risk factors for GAE included male gender, exposures in southern-tier US states, Hispanic ethnicity in California, occupational or recreational contacts with soil, and recent organ transplantation. Fatal free-living amebic infections of the brain are increasing today due to more frequent environmental, recreational, and occupational exposures; organ transplantation; and unanticipated clusters of PAM due to N. fowleri inoculations following nasal sinus irrigation using neti pots filled with municipal tap water. Potential organ donors dying from meningoencephalitis of unexplained causes should be screened for free-living amebic infections of the brain capable of hematogenous dissemination in organ recipients.

Primary amebic meningoencephalitis in Florida: a case report and epidemiological review of Florida cases

Primary amebic meningoencephalitis (PAM) is a rare but nearly always fatal infection of the central nervous system caused by the thermophilic, free-living ameba Naegleria fowleri. Since its first description in 1965 through 2010, 118 cases have been reported in the U.S.; all cases are related to environmental exposure to warm freshwater; most have occurred in children and adolescents and are associated with recreational water activities, such as swimming, diving, or playing in freshwater lakes, ponds, or rivers. Over one-fourth of all national PAM cases have occurred in Florida. The authors describe here a fatal case of PAM in a resident of northeast Florida and the ensuing environmental and public health investigation; they also provide a review of all cases of PAM in Florida from 1962 to 2010 and discuss public health responses to PAM in Florida, highlighting opportunities for positive collaboration between state and local environmental health specialists, epidemiologists, and the Centers for Disease Control and Prevention.

Youngest survivor of naegleria meningitis

Primary amebic meningoencephalitis (PAME) is a rare condition, usually caused by free living motile amebae. These are universally fatal infections with very few survivors reported till now. The authors report a 25-d-old boy, the youngest survivor of Naegleria meningitis. The child was admitted with a diagnosis of partially treated meningitis. Cerebro-spinal fluid wet mount examination revealed free living motile amebae resembling Naegleria, which was further confirmed by culture. He was treated with amphoterecin B, rifampicin and fluconazole for 4 wk and ventriculoperitoneal shunt for obstructive hydrocephalous. At 8 mo follow up, child has survived with neurological sequlae.

Acanthamoeba meningoencephalitis presenting as neuropsychiatric lupus in a pediatric patient

We present the case of a 16-year-old patient with systemic lupus erythematosus who presented with altered mental status and regressive behaviour. She was worked up and empirically treated for common and opportunistic infectious agents. All work-up was negative and after an extensive course of antibiotics she was treated for neuropsychiatric lupus with cytoxan. She initially responded, but this was short-lived and she eventually became comatose and passed away. On brain biopsy she was found to have numerous trophozoites with round nucleus, prominent nucleolus and thin nuclear membrane. Methenamine silver stain showed encysted amoeba, corresponding with a diagnosis of acanthamoeba meningoencephalitis. Making the diagnosis of acanthamoeba meningoencephalitis requires a high degree of suspicion. Specific serum antibodies may not be a reliable measure in immunocompromised patients and trophozoites in CSF can be confused with monocytes. Brain biopsy may be required to make a definitive diagnosis. It is important for clinicians treating immunocompromised patients to keep this agent in mind in an immunocompromised patient with neurological manifestations. Acanthamoeba infections have only been reported in a small handful of patients and, to our knowledge, this is the first reported case in the United States.

Primary amoebic meningo-encephalitis due to Naegleria fowleri

Primary amoebic meningo-encephalitis is a fulminant, often rapidly fatal infection affecting individuals with a recent history of swimming in warm fresh water. A fatal case of primary amoebic meningoencephalitis due to Naegleria fowleri in a 35 years old male suffering from human immunodeficiency virus with pulmonary tuberculosis infection is reported. Naegleria fowleri was diagnosed by wet mount examination of cerebrospinal fluid and the diagnosis was confirmed by culture of the cerebrospinal fluid on non-nutrient agar layered with Escherichia coli. The patient was treated with amphotericin B and antituberculous treatment but the outcome was fatal. Primary amoebic meningo-encephalitis should be suspected in every case of pyogenic meningo-encephalitis in which no bacteria or fungus is found on cerebrospinal fluid examination.

[Amebic meningoencephalitis]

It has been reported that amebic meningoencephalitis is caused by some rhizopods, which are taxonomically different from Entamoeba histolytica which is well known as the causative agent of amebic dysentery. Different types of human meningoencephalitis have been reported to be caused by amphizoic amebae, which are not obligatorily parasitic (endozoic) but are usually free-living (exozoic) in nature, i.e., in environmental water and soil: Naegleria fowleri causes acute primary amebic meningoencephalitis (PAM). Acanthamoeba spp. and Balamuthia mandrillaris produce chronic and opportunistic granulomatous amebic (meningo) encephalitis (GAE). Further, most recently, Sappinia diploidea has been identified as an agent that causes comparatively acute type of encephalitis.

Primary amoebic meningoencephalitis due to Naegleria fowleri

Primary amoebic meningoencephalitis (PAM) due to Naegleria fowleri was detected in a 36-year-old, Indian countryman who had a history of taking bath in the village pond. He was admitted in a semi comatosed condition with severe frontal headache, neck stiffness, intermittent fever, nausea, vomiting, left hemiparesis and seizures. Computerized tomography (CT) scan of brain showed a soft tissue non-enhancing mass with erosion of sphenoid sinus. However CSF findings showed no fungal or bacterial pathogen. Trophozoites of Naegleria fowleri were detected in the direct microscopic examination of CSF and these were grown in culture on non-nutrient agar. The patient was put on amphotericin-B, rifampicin and ceftazidime but his condition deteriorated and was taken home by his relatives in a moribund condition against medical advice and subsequently died. A literature review of 7 previous reports of PAM in India is also presented. Four of theses eight cases were non lethal. The mean age was 13.06 years with male: female ratio of 7:1. History of contact with water was present in four cases. Trophozoites could be identified in all 8 cases in this series.

[Criteria for diagnosis of the neurological stage of human African trypanosomiasis: update and perspectives]

Sleeping sickness or human African trypanosomiasis (HAT) is due to parasite infection by a sanguicolous flagellate protozoan of the Trypanosoma brucei genus. The disease is classically divided into two stages, i.e., the hemolymphatic stage and the CNS stage. Disease staging is currently a major challenge for therapeutic decision-making. In the field, diagnosis is based solely on white blood cell (WBC) count and detection of the parasite in the patient's cerebrospinal fluid (CSF). This technique is unreliable and invasive. Numerous studies are now under way to adapt staging to field conditions and to develop a reliable, low-cost, non-invasive test. This article describes the mechanisms underlying CNS involvement during HAT and reviews the different techniques now being studied to simplify and improve diagnosis of the CNS stage.

Molecular identification of Trypanosoma cruzi I tropism for central nervous system in Chagas reactivation due to AIDS

Trypanosoma cruzi lineages, microsatellite allelic polymorphism, and mithocondrial gene haplotypes were directly typified from peripheral blood and cerebrospinal fluid specimens of a Bolivian patient with Chagas disease with accompanying AIDS and central nervous system severe involvement. Of note, the patient's blood was infected by a mixture of T. cruzi I and T. cruzi IId/e polyclonal populations while the cerebrospinal fluid showed only a monoclonal T. cruzi I population. Our findings do not corroborate the original assumption of innocuity for T. cruzi I in the southern cone of the Americas and highlight lineage I tropism for central nervous system causing lethal Chagas reactivation.

Plasmodium vivax cerebral malaria

We report two cases of Plasmodium vivax malaria (both aged 12 years) complicated by seizures and symptoms of diffuse meningoencephalitis. One had predominantly meningeal signs while in the other, purely encephalitis features were present. Both cases were treated with artesunate. Rarely, cerebral malaria is a presenting complication or occurs during the course of P. vivax infection.

Disseminated acanthamoeba infection in a renal transplant recipient: a case report

Acanthamoeba species are free-living amoebae that are the causative agents of chronic granulomatous meningoencephalitis, amoebic keratitis, pulmonary lesions, cutaneous lesions and sinusitis. Immunocompromised individuals are particularly susceptible to infections with Acanthamoeba, which can be disseminated at times. We herewith report the autopsy findings of disseminated Acanthamoeba infection in a 36-year-old female, a renal transplant recipient on immunosupressants for last four years. Central nervous system showed Acanthamoeba associated chronic granulomatous meningoencephalitis, with predominant perivascular infiltrate of amoebic cysts, trophozoites and inflammatory cells. Both lungs and pancreas also showed infiltration with Acanthamoeba.