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An Overview of Parasite Diversity
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
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.
Central Nervous System Infections
Published in Miriam Orcutt, Clare Shortall, Sarah Walpole, Aula Abbara, Sylvia Garry, Rita Issa, Alimuddin Zumla, Ibrahim Abubakar, Handbook of Refugee Health, 2021
Meningoencephalitis is defined as inflammation of both the meninges and the brain. Most organisms that can cause meningitis or encephalitis can cause meningoencephalitis. Rarer aetiologies to consider include primary amoebic meningoencephalitis, which is associated with swimming in warm fresh water, and Naegleria fowleri, which is transmitted intranasally, leading to CNS invasion. Meningoencephalitis presents with fever, meningism and convulsions.
Diagnosing Parasitic Infections
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
Schistosomal infections can cause tropical spastic paraplegia. Primary amoebic meningoencephalitis occurs when Naegleria fowleri gains entrance to the brain through the nose after exposure to contaminated water.
Inhibition studies of the protozoan α-carbonic anhydrase from Trypanosoma cruzi with phenols
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Alessandro Bonardi, Seppo Parkkila, Claudiu T. Supuran
Protozoans are microscopic, nonfilamentous protists belonging to a multitude of phyla, with many genera and species described so far, many of which possess ecological and industrial relevance. However, they sometimes produce disease in vertebrates, which may range from mild to moderate, such as those induced by Toxoplasma gondii or Entamoeba histolytica, or may lead to more serious conditions, in the case of infections due to Cryptosporidium parvum, Giardia lamblia, Trichomonas vaginalis, Babesia spp., but also very serious and widespread ones, such as malaria, leishmaniasis, Chagas disease, and African sleeping disease1,2. Although rare, there are also several fatal protozoal diseases, mostly provoked by amoebae belonging to Naegleria fowleri, Acanthamoeba spp. and Balamuthia mandrillaris genera/species1. Few effective therapeutic approaches are available so far for treating most diseases provoked by protozoans1. Albeit all 12 protozoans genera which produce human disease are well studied by now, there are few drugs useful for treating them. Furthermore, these drugs have been available for many decades, generally show high toxicity and low therapeutic indexes, and more concerning, extensive resistance to these treatment options has developed in the last period1,2.
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.
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.