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Parasites & Vectors Jan 2021Toxoplasma gondii is a protozoan parasite with a complex life cycle and a cosmopolitan host range. The asexual part of its life cycle can be perpetually sustained in a... (Review)
Review
Toxoplasma gondii is a protozoan parasite with a complex life cycle and a cosmopolitan host range. The asexual part of its life cycle can be perpetually sustained in a variety of intermediate hosts through a combination of carnivory and vertical transmission. However, T. gondii produces gametes only in felids after the predation of infected intermediate hosts. The parasite changes the behavior of its intermediate hosts by reducing their innate fear to cat odors and thereby plausibly increasing the probability that the definitive host will devour the infected host. Here, we provide a short description of such parasitic behavioral manipulation in laboratory rodents infected with T. gondii, along with a bird's eye view of underpinning biological changes in the host. We also summarize critical gaps and opportunities for future research in this exciting research area with broad implications in the transdisciplinary study of host-parasite relationships.
Topics: Animals; Behavior, Animal; Cats; Fear; Host-Parasite Interactions; Humans; Life Cycle Stages; Odorants; Rodentia; Toxoplasma; Toxoplasmosis, Animal
PubMed: 33494777
DOI: 10.1186/s13071-020-04528-x -
The Veterinary Clinics of North... Aug 2022Advances in the understanding of equine protozoal myeloencephalitis (EPM) are reviewed. It is now apparent that EPM can be caused by either of 2 related protozoan... (Review)
Review
Advances in the understanding of equine protozoal myeloencephalitis (EPM) are reviewed. It is now apparent that EPM can be caused by either of 2 related protozoan parasites, Sarcocystis neurona and Neospora hughesi, although S neurona is the most common etiologic pathogen. Horses are commonly infected, but clinical disease occurs only infrequently; the factors influencing disease occurrence are not well understood. Epidemiologic studies have identified risk factors for the development of EPM, including the presence of opossums and prior stressful health-related events. Attempts to reproduce EPM experimentally have reliably induced antibody responses in challenged horses, but have not consistently produced neurologic disease. Diagnosis of EPM has improved by detecting intrathecal antibody production against the parasite. Sulfadiazine/pyrimethamine (ReBalance) and the triazine compounds diclazuril (Protazil) and ponazuril (Marquis) are effective anticoccidial drugs that are now available as FDA-approved treatments for EPM.
Topics: Animals; Coccidiosis; Encephalomyelitis; Horse Diseases; Horses; Sarcocystis; Sarcocystosis
PubMed: 35810151
DOI: 10.1016/j.cveq.2022.05.003 -
Trends in Parasitology Dec 2023Chicken coccidiosis, caused by infection with single or multiple Eimeria species, results in significant economic losses to the global poultry industry. Over the past... (Review)
Review
Chicken coccidiosis, caused by infection with single or multiple Eimeria species, results in significant economic losses to the global poultry industry. Over the past decades, considerable efforts have been made to generate attenuated Eimeria strains, and the use of live attenuated anticoccidial vaccines for disease prevention has achieved tremendous success. In this review, we evaluate the advantages and limitations of the methods of attenuation as well as attenuated Eimeria strains in a historical perspective. Also, we summarize the recent exciting research advances in transient/stable transfection systems and clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing developed for Eimeria parasites, and discuss trends and challenges of developing live attenuated anticoccidial vaccines based on transgenesis and genome editing.
Topics: Animals; Chickens; Vaccines, Attenuated; Poultry Diseases; Protozoan Vaccines; Coccidiosis; Eimeria
PubMed: 37770352
DOI: 10.1016/j.pt.2023.09.002 -
Clinical Microbiology Reviews Mar 2024Schistosomiasis is a neglected tropical disease caused by the helminth spp. and has the second highest global impact of all parasites. are transmitted through contact... (Review)
Review
Schistosomiasis is a neglected tropical disease caused by the helminth spp. and has the second highest global impact of all parasites. are transmitted through contact with contaminated fresh water predominantly in Africa, Asia, the Middle East, and South America. Due to the widespread prevalence of , co-infection with other infectious agents is common but often poorly described. Herein, we review recent literature describing the impact of co-infection between species and co-infection with blood-borne protozoa, soil-transmitted helminths, various intestinal protozoa, , , various urinary tract infection-causing agents, and viral pathogens. In each case, disease severity and, of particular interest, the immune landscape, are altered as a consequence of co-infection. Understanding the impact of schistosomiasis co-infections will be important when considering treatment strategies and vaccine development moving forward.
Topics: Humans; Coinfection; Schistosomiasis; Africa; Soil; Prevalence; Helminthiasis
PubMed: 38319102
DOI: 10.1128/cmr.00098-23 -
Journal of Neurovirology Dec 2022The report of death of a person from amebic meningoencephalitis, the proverbial "brain-eating ameba," Naegleria fowleri, acquired in a state park lake in Iowa in July... (Review)
Review
The report of death of a person from amebic meningoencephalitis, the proverbial "brain-eating ameba," Naegleria fowleri, acquired in a state park lake in Iowa in July 2022 has once again raised the seasonal alarms about this pathogen. While exceptionally rare, its nearly universal fatality rate has panicked the public and made for good copy for the news media. This review will address free-living ameba that have been identified as causing CNS invasion in man, namely, Naegleria fowleri, Acanthamoeba species, Balamuthia mandrillaris, and Sappinia diploidea (Table 1). Of note, several Acanthamoeba spp. and Balamuthia mandrillaris may also be associated with localized extra-CNS infections in individuals who are immunocompetent and disseminated disease in immunocompromised hosts. These ameba are unique from other protozoa in that they are free-living, have no known insect vector, do not result in a human carrier state, and are typically unassociated with poor sanitation. Table 1 Free-living ameba that have been identified as causing CNS invasion in man, namely, Naegleria fowleri, Acanthamoeba species, Balamuthia mandrillaris, and Sappinia diploidea Entity Pathogenic ameba Predisposing disorders Portal of entry Incubation period Clinical features Radiographic findings CSF finding Diagnostic measures Primary amebic meningoencephalitis Naegleria fowleri; N. australiensis; N. italica Previously healthy children or young adults Olfactory epithelium 2-14 days (average 5 days) Headache, fever, altered mental status, meningeal signs; seizures Brain edema; meningeal enhancement; hydrocephalus; basal ganglia infarctions Increased opening pressure; neutrophilic pleocytosis (~ 1000 cells/cu mm); low glucose Brain biopsy, CSF wet prep, IIF culture or PCR Granulomatous amebic encephalitis Acanthamoeba spp.; Balamuthia mandrillaris; Sappinia diploidea Typically, immunocompromised individual Skin sinuses; olfactory epithelium respiratory tract Weeks to months Headache; altered mental status seizures, focal neurological findings Focal parenchymal lesions with edema; hemorrhagic infarctions; meningeal enhancement Generally, LP contraindicated; when performed lymphocytic pleocytosis; increased protein; low glucose Brain biopsy, CSF culture, wet prep, IIF, or PCR IIF indirect immunofluorescence, LP lumbar puncture, PCR polymerase chain reaction.
Topics: Child; Humans; Leukocytosis; Amebiasis; Amoeba; Acanthamoeba; Naegleria fowleri; Central Nervous System; Headache; Infarction; Glucose
PubMed: 36098909
DOI: 10.1007/s13365-022-01096-x -
Frontiers in Cellular and Infection... 2022Parasitic infections caused by protozoans that infect the mucosal surfaces are widely neglected worldwide. Collectively, spp. and infect more than a billion people in... (Review)
Review
Parasitic infections caused by protozoans that infect the mucosal surfaces are widely neglected worldwide. Collectively, spp. and infect more than a billion people in the world, being a public health problem mainly in developing countries. However, the exact incidence and prevalence data depend on the population examined. These parasites ultimately cause pathologies that culminate in liver abscesses, malabsorption syndrome, vaginitis, and urethritis, respectively. Despite this, the antimicrobial agents currently used to treat these diseases are limited and often associated with adverse side effects and refractory cases due to the development of resistant parasites. The paucity of drug treatments, absence of vaccines and increasing problems of drug resistance are major concerns for their control and eradication. Herein, potential candidates are reviewed with the overall aim of determining the knowledge gaps and suggest future perspectives for research. This review focuses on this public health problem and focuses on the progress of drug repositioning as a potential strategy for the treatment of mucosal parasites.
Topics: Animals; Cryptosporidiosis; Cryptosporidium; Entamoeba histolytica; Feces; Female; Giardia lamblia; Humans; Mucous Membrane; Parasites
PubMed: 35548465
DOI: 10.3389/fcimb.2022.860442 -
Current Opinion in Microbiology Dec 2019Many microbial eukaryotes exhibit cell-cell communication to co-ordinate group behaviours as a strategy to exploit a changed environment, adapt to adverse conditions or... (Review)
Review
Many microbial eukaryotes exhibit cell-cell communication to co-ordinate group behaviours as a strategy to exploit a changed environment, adapt to adverse conditions or regulate developmental responses. Although best characterised in bacteria, eukaryotic microbes have also been revealed to cooperate to optimise their survival or dissemination. An excellent model for these processes are African trypanosomes, protozoa responsible for important human and animal disease in sub Saharan Africa. These unicellular parasites use density sensing in their mammalian host to prepare for transmission. Recently, the signal and signal transduction pathway underlying this activity have been elucidated, revealing that the parasite exploits oligopeptide signals generated by released peptidases to monitor cell density and so generate transmission stages. Here we review the evidence for this elegant quorum sensing mechanism and its parallels with similar mechanisms in other microbial systems. We also discuss its implications for disease spread in the context of coinfections involving different trypanosome species.
Topics: Africa South of the Sahara; Animals; Coinfection; Humans; Quorum Sensing; Signal Transduction; Trypanosoma brucei brucei; Trypanosomiasis, African
PubMed: 31442903
DOI: 10.1016/j.mib.2019.07.001 -
Trends in Parasitology Jul 2023Piroplasmids of the genera Babesia, Theileria, and Cytauxzoon are tick-transmitted parasites with a high impact on animals and humans. They have complex life cycles in... (Review)
Review
Piroplasmids of the genera Babesia, Theileria, and Cytauxzoon are tick-transmitted parasites with a high impact on animals and humans. They have complex life cycles in their definitive arthropod and intermediate vertebrate hosts involving numerous processes, including invasion of, and egress from, host cells, parasite growth, transformation, and migration. Like other parasitic protozoa, piroplasmids are equipped with different types of protease to fulfill many of such essential processes. Blockade of some key proteases, using inhibitors or antibodies, hinders piroplasmid growth, highlighting their potential usefulness in drug therapies and vaccine development. A better understanding of the functional significance of these enzymes will contribute to the development of improved control measures for the devastating animal and human diseases caused by these pathogens.
Topics: Animals; Humans; Peptide Hydrolases; Babesia; Piroplasmida; Theileria; Ticks; Babesiosis
PubMed: 37271664
DOI: 10.1016/j.pt.2023.04.010 -
Frontiers in Molecular Biosciences 2024
PubMed: 38800093
DOI: 10.3389/fmolb.2024.1422955 -
Gastroenterology Clinics of North... Jun 2020Hepatosplenic candidiasis and other fungal infections of the liver are uncommon in healthy individuals; however, high index of suspicion is essential in... (Review)
Review
Hepatosplenic candidiasis and other fungal infections of the liver are uncommon in healthy individuals; however, high index of suspicion is essential in immunocompromised patients with prolonged fever. Parasitic infections are protozoan or helminthic; their distribution and epidemiology are variable among different world regions. Clonorchiasis, opisthorchiasis, fascioliasis, and ascariasis are helminthic infections that commonly involve the biliary systems. Signs and symptoms of cholangitis require prompt management to relieve biliary obstruction; addition of antihelminthic agents is essential. Parasitic infections are mostly transmitted to humans by fecally contaminated food and water. Proper hand and food sanitation measures are essential in preventing disease transmission.
Topics: Anthelmintics; Ascariasis; Cholangiopancreatography, Endoscopic Retrograde; Cholestasis; Clonorchiasis; Fascioliasis; Fever; Helminthiasis; Hepatitis; Humans; Immunocompromised Host; Liver Diseases, Parasitic; Mycoses; Opisthorchiasis
PubMed: 32389369
DOI: 10.1016/j.gtc.2020.01.009