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.

Naegleria fowleri-associated meningoencephalitis in a cow in Southern Brazil-first molecular detection of N. fowleri in Brazil.

Naegleria fowleri, a free-living and thermophilic ameba, is the etiological agent of primary amebic meningoencephalitis (PAM). PAM is a rare and highly fatal neurologic disease in humans, and has been rarely documented in animal species. This report describes the pathological and etiological findings of a fatal case of N. fowleri-associated meningoencephalitis in a cow in Southern Brazil. Microscopic findings were consistent with severe, multifocal, hemorrhagic, and necrosuppurative meningoencephalitis associated with a large number of amebic trophozoites compatible with N. fowleri. Brain samples subjected to molecular assays generated a 315 bp fragment, which presented 99% identity with a N. fowleri sequence previously deposited in GenBank. This is the first study reporting the molecular detection of N. fowleri in a case of cattle meningoencephalitis in Latin America, and the obtained sequence represents the first GenBank deposit of N. fowleri identified in Brazil to this day. Additionally, the case reported is the second occurrence of N. fowleri-associated disease in the same city, drawing attention to the local importance of infection by this ameba and potential risk for human infections.

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.

Detection of serum antibodies in children and adolescents against Balamuthia mandrillaris, Naegleria fowleri and Acanthamoeba T4.

The presence of free-living amoebae of the genera Naegleria, Acanthamoeba and Balamuthia, which contain pathogenic species for humans and animals, has been demonstrated several times and in different natural aquatic environments in the northwest of Mexico. With the aim of continuing the addition of knowledge about immunology of pathogenic free-living amoebae, 118 sera from children and adolescents, living in three villages, were studied. Humoral IgG response against B. mandrillaris, N. fowleri and Acanthamoeba sp. genotype T4, was analyzed in duplicate to titers 1: 100 and 1: 500 by enzyme-linked immunosorbent assay (ELISA). Children and adolescents ages ranged between 5 and 16 years old, with a mean of 9 years old, 55% males. All tested sera were positive for the 1: 100 dilution, and in the results obtained with the 1: 500 dilution, 116 of 118 (98.3%) were seropositive for N. fowleri, 101 of 118 (85.6%) were seropositive for Acanthamoeba sp. genotype T4, and 43 of 118 (36.4%) were seropositive for B. mandrillaris. The statistical analysis showed different distributions among the three communities and for the three species of pathogenic free-living amoebae, including age. Lysed and complete cells used as Balamuthia antigens gave differences in seropositivity.

Survey of Naegleria fowleri in geothermal recreational waters of Guadeloupe (French West Indies).

In 2008 a fatal case of primary amoebic meningoencephalitis, due to the amoeboflagellate Naegleria fowleri, occurred in Guadeloupe, French West Indies, after a child swam in a bath fed with geothermal water. In order to improve the knowledge on free-living amoebae in this tropical part of France, we investigated on a monthly basis, the presence of Naegleria spp. in the recreational baths, and stream waters which feed them. A total of 73 water samples, 48 sediments and 54 swabs samples were collected from 6 sampling points between June 2011 and July 2012. The water samples were filtered and the filters transferred to non-nutrient agar plates seeded with a heat-killed suspension of Escherichia coli while sediment and swab samples were placed directly on these plates. The plates were incubated at 44°C for the selective isolation of thermophilic Naegleria. To identify the Naegleria isolates the internal transcribed spacers, including the 5.8S rDNA, were amplified by polymerase chain reaction and the sequence of the PCR products was determined. Thermophilic amoebae were present at nearly all collection sites. The pathogenic N. fowleri was the most frequently encountered thermophilic species followed by N. lovaniensis. The concentration of N. fowleri was rather low in most water samples, ranging from 0 to 22 per liter. Sequencing revealed that all N. fowleri isolates belonged to a common Euro-American genotype, the same as detected in the human case in Guadeloupe. These investigations need to be continued in order to counsel the health authorities about prevention measures, because these recreational thermal baths are used daily by local people and tourists.

Balamuthia mandrillaris infection of the skin and central nervous system: an emerging disease of concern to many specialties in medicine.

PURPOSE OF REVIEW: Balamuthia mandrillaris infection of the skin and central nervous system has been increasingly reported in the last decade, making this entity a genuine emerging disease. The ability of the clinician in recognizing the skin lesion early in the course of the disease may lead to a successful therapeutic intervention in an otherwise fatal disease. RECENT FINDINGS: In the past years, advances have been made regarding knowledge about the ubiquity of the ameba in the environment, its worldwide distribution (with higher prevalence in South America), the patients at risk (particularly those of Hispanic origin), the diagnostic methods (including those based on molecular biology) and the different therapeutic strategies that have resulted in survival of patients. A recent report dealing with organ transplant transmission of this infection has made it a subject of interest in transplant medicine. SUMMARY: The present review will allow readers from different fields (clinician, dermatologist, neurologist, infectious disease and transplant specialist) to become familiar with the clinical aspect of the disease, including diagnosis and therapy.

Reactivation of Chagas disease with central nervous system involvement in HIV-infected patients in Argentina, 1992-2007.

OBJECTIVES: The objective of this study was to evaluate clinical and microbiological characteristics of Chagas disease (ChD) with central nervous system (CNS) involvement in AIDS patients. METHODS: This was a retrospective study of clinical and laboratory findings of HIV-infected patients with a confirmed diagnosis of ChD involving the CNS during the period 1992-2007 at the "Francisco J. Muñiz" Infectious Diseases Hospital, Buenos Aires, Argentina. RESULTS: Of a total of 15 patients, 14 were male and the median age was 33 years (range 25-54 years). Seven out of nine had lived in a Chagas endemic area and 7/10 were intravenous drug users (IDUs). The disease was reactivated during corticosteroid therapy in three patients. Clinical manifestations were: headache (11/15), focal neurological deficits (9/15), fever (9/15), meningismus (7/15), seizures (7/15), altered mental status (5/15), and cardiac involvement (3/10). The median CD4 T-cell count at the time of reactivation was 64cells/microl (range 1-240). Twelve of 14 had positive serology for Trypanosoma cruzi; the two negative were IDUs. Cerebrospinal fluid (CSF) findings (median (range)): cell count 5/mm(3) (2-90), protein level 0.68g/l (0.1-1.84), and glucose level 0.45g/l (0.13-0.73). CSF direct examination for T. cruzi was positive in 11/13. Neuroimaging findings showed a single hypodense lesion in 7/14 and normal images in 2/14. Twelve patients were treated with benznidazole. The global mortality was 79% (11/14). CONCLUSIONS: ChD reactivation should be considered as a differential diagnosis of meningoencephalitis in HIV patients with low CD4 T-cell counts, previous residency in an endemic area, and/or IDUs. Whenever possible, lumbar puncture should be performed because of the high accuracy for early diagnosis.

[Granulomatous amebic encephalitis caused by Balamuthia mandrillaris. First case diagnosed in Chile]. / Encefalitis amebiana granulomatosa por Balamuthia mandrillaris. Primer caso diagnosticado en Chile.

The case of a 7 month-old baby boy is presented, with a history of several weeks of evolution of personality changes, convulsions and fever. While he was hospitalized, the brain image study showed multifocal cavity lesions, which varied from millimeters to 4 cm of diameter, not producing mass effect. Their biopsy revealed necrotizing encephalitis. In spite of treatment, the lesions progressed and the boy died. The autopsy demonstrated an extensive necrotizing encephalitis with fibrinoid necrotic arteritis, signs of organization, and the presence of parasitic elements with characteristics of trophozoites and cysts of free-living amoebas belonging to the genus Acanthamoeba or Balamuthia. In addition, hypoplasia-dysplasia of the thymus and signs of shock were found. The morphologic elements correspond to the disease described as granulomatous amebic encephalitis and the agent found was identified as Balamuthia mandrillaris (Centers for Diseases Control and Prevention, Atlanta, USA ).

AIDS and Chagas' disease.

Chagas' disease can reactivate in patients with AIDS and present as a brain mass lesion or an acute diffuse meningoencephalitis indistinguishable from other opportunistic infections or neoplastic processes, such as toxoplasma encephalitis or central nervous system (CNS) primary lymphoma. The CNS tumor-like lesion is the most common manifestation of Chagas' disease reactivation in AIDS patients. The prognosis of untreated cases is grim and underscore the need for safe and effective therapeutic agents.