Water-based disease and microbial growth *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Naegleria fowleri occurs in low numbers in surface waters; however, when the water temperature exceeds 35 oC (hot springs, lakes, groundwater) it can grow to large numbers (Percival et al., 2004). It is an amoeboflagellate, changing forms between cysts, amoeba and a free-swimming flagellate. Infection occurs by the flagellate form entering the nose (usually during head immersion while swimming) where it sheds its flagella. The amoeba form follows the nerves to the brain, where it begins to destroy the brain tissue, causing primary amoebic meningoencephalitis (PAM). Death usually follows within four to six days with 98 per cent mortality. It usually infects young children and young adults, although infant cases have been reported in India. Cases have been reported in Australia and the United States related to the use of treated tap water for nasal cleaning. The illness is rare, with only a little over 400 cases reported worldwide. The organism has similar resistance to free chlorine as Giardia cysts, but is much more resistant to UV light disinfection.
An Overview of Parasite Diversity
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2023
Discoba is an example of a group of organisms strongly supported and united by similar sequences in a number of genes but for which it is hard to define a unifying morphological trait. Nonetheless, included are some important parasite groups. One representative of note is Naegleria fowleri (Figure 2.9B) which typically dwells in warm, aerobic aquatic habitats, including some swimming pools. It can assume an amoeboid morphology, may transiently grow two flagella for swimming and dispersal and then disassemble them, or it can round up and encyst. It is worth mentioning here because occasionally people swimming in a habitat occupied by N. fowleri snuff this organism deep into their nasal chambers. If so, it can move through the small passages in the cribiform plate that separates the nasal chamber from the brain. It then begins to phagocytose cells of the brain, an ailment called primary amebic meningoencephalitis, or PAM. N. fowleri is frequently characterized as an opportunistic parasite though human infections for the otherwise free-living organism are a dead end. Infections, though rare, are almost always fatal for the affected person.
Liposomal Amphotericin B
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
Naegleria fowleri is a free-living amoeba that can cause primary amoebic meningoencephalitis (PAM), an extremely rare yet almost universally fatal infection of the CNS. DAmB has been part of treatment regimens in the few cases of survival (Vargas-Zepeda et al., 2005). A mouse model found LAmB to be less effective than DAmB in vitro (Goswick and Brenner, 2003); therefore liposomal formulations of AmB are generally avoided in the treatment of PAM.
Brain-eating amoebae: is killing the parasite our only option to prevent death?
Published in Expert Review of Anti-infective Therapy, 2022
Naveed Ahmed Khan, Jibran Sualeh Muhammad, Ruqaiyyah Siddiqui
Naegleria fowleri is a free-living protist pathogen with the ability to produce fatal infection of the central nervous system with over 95% mortality rate [1–3]. It is considered to be one of the deadliest parasites known to humans, i.e., if contracted, it almost always results in death. Being free-living, it is widely distributed in the environment, particularly in warm freshwater [1–3]. Humans and animals contract this parasite when exposed to contaminated water. Parasites enter via the nose and then traverse the olfactory neuroepithelial route to invade the central nervous system (CNS) via porous cribriform. Once there is involvement of the CNS, it almost always warrants mortality. This is owing to the inefficacy of drugs to kill the parasite effectively [1]. Although advances in antimicrobial therapy over the past several decades have been made, it is distressing that the mortality rate has remained significant, suggesting the need to find effective therapies. A complete understanding of the biology of the parasite and its pathogenetic mechanisms will elucidate targets for the rational development of therapeutic interventions.
Opportunistic free-living amoebal pathogens
Published in Pathogens and Global Health, 2022
Mohammad Ridwane Mungroo, Naveed Ahmed Khan, Sutherland Maciver, Ruqaiyyah Siddiqui
Pathogenic free-living amoebae, such as Acanthamoeba spp., Naegleria fowleri and Balamuthia mandrillaris, cause infection of the central nervous system (CNS) [1, 2]. The detection of brain-eating amoebae in drinking water supplies is of concern, which further indicates the severe threat posed by free-living amoebae to communities [3–6]. Furthermore, infection of the CNS with Acanthamoeba spp., Naegleria fowleri and Balamuthia mandrillaris almost always leads to mortality [7]. Moreover, cases of amoebic infection are under-reported worldwide, because of lack of awareness and diagnostic modalities, as well as misdiagnosis, due to similarity in symptoms, of amoebic infection of CNS to other common CNS infections such as bacterial meningitis, and thus, the true burden of cases due to these amoebae is unknown [8,9].
Naegleria fowleri: diagnosis, treatment options and pathogenesis
Published in Expert Opinion on Orphan Drugs, 2019
Mohammad Ridwane Mungroo, Naveed Ahmed Khan, Ruqaiyyah Siddiqui
Initially discovered in 1899, Naegleria fowleri is known to instigate fatal infection of the central nervous system, identified as primary amoebic meningoencephalitis (PAM) [1,2]. These ‘brain-eating amoebae’ invade the nervous system via the nose, after contaminated water is powerfully inhaled into the nose, and slowly creep up into the brain tissue resulting in severe hemorrhaging and inflammation leading to extensive brain tissue devastation within days [3]. In spite of improvements in diagnostics, antimicrobial chemotherapy and supportive care, the mortality linked with PAM has remained more than 95% indicating (i) the virulent nature of this pathogen, and (ii) the lack of effective treatment against this disease [4]. N. fowleri infections have been reported in healthy individuals, mainly children and young adults, who have a history of swimming, bathing, ritual ablution or nasal irrigation. Numerous cases of PAM have been described globally, with mortality rates of more than 90% [5]. These amoebae and associated infections have gathered growing scientific/medical interest in recent years due to poor prognosis, i.e. less than 5% survival if early intervention is not initiated [3]. In addition to poor prognosis, cases of PAM are frequently under-reported and under-recognized worldwide due to lack of awareness, advent or availability of diagnostic measures, limitation in treatment modalities, access to wide distribution of knowledge on public health issues especially in developing countries and similarity of symptomatology with other common causes of CNS infections such as bacterial meningitis [3]. Moreover, a comprehensive understanding of the pathogenesis and pathophysiology of CNS infection due to N. fowleri is incompletely understood. The purpose of this review is to provide the current understanding of N. fowleri pathogenesis, diagnosis and treatment.
Related Knowledge Centers
- Amoeba
- Bacteria
- Cerebrospinal Fluid
- Flagellate
- Trophozoite
- Cell Nucleus
- Pathogen
- Naegleriasis
- Water Chlorination
- Microbial Cyst