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Frontiers in Cellular and Infection... 2017The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen . Given their impact on human health, species and the mechanisms... (Review)
Review
The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen . Given their impact on human health, species and the mechanisms responsible for their replication within host cells are often studied in alveolar macrophages, the primary human cell type associated with disease. Despite the potential severity of individual cases of disease, are not spread from person-to-person. Thus, from the pathogen's perspective, interactions with human cells are accidents of time and space-evolutionary dead ends with no impact on 's long-term survival or pathogenic trajectory. To understand as a pathogen is to understand its interaction with its natural hosts: the polyphyletic protozoa, a group of unicellular eukaryotes with a staggering amount of evolutionary diversity. While much remains to be understood about these enigmatic hosts, we summarize the current state of knowledge concerning 's natural host range, the diversity of -protozoa interactions, the factors influencing these interactions, the importance of avoiding the generalization of protozoan-bacterial interactions based on a limited number of model hosts and the central role of protozoa to the biology, evolution, and persistence of in the environment.
Topics: Acanthamoeba; Amoeba; Amoebida; Biodiversity; Biological Evolution; Environment; Hartmannella; Host-Pathogen Interactions; Legionella; Legionella pneumophila; Legionnaires' Disease; Macrophages, Alveolar; Naegleria
PubMed: 29250488
DOI: 10.3389/fcimb.2017.00477 -
Microbiology and Molecular Biology... Dec 2012A wide spectrum of pathogenic bacteria and protozoa has adapted to an intracellular life-style, which presents several advantages, including accessibility to host cell... (Review)
Review
A wide spectrum of pathogenic bacteria and protozoa has adapted to an intracellular life-style, which presents several advantages, including accessibility to host cell metabolites and protection from the host immune system. Intracellular pathogens have developed strategies to enter and exit their host cells while optimizing survival and replication, progression through the life cycle, and transmission. Over the last decades, research has focused primarily on entry, while the exit process has suffered from neglect. However, pathogen exit is of fundamental importance because of its intimate association with dissemination, transmission, and inflammation. Hence, to fully understand virulence mechanisms of intracellular pathogens at cellular and systemic levels, it is essential to consider exit mechanisms to be a key step in infection. Exit from the host cell was initially viewed as a passive process, driven mainly by physical stress as a consequence of the explosive replication of the pathogen. It is now recognized as a complex, strategic process termed "egress," which is just as well orchestrated and temporally defined as entry into the host and relies on a dynamic interplay between host and pathogen factors. This review compares egress strategies of bacteria, pathogenic yeast, and kinetoplastid and apicomplexan parasites. Emphasis is given to recent advances in the biology of egress in mycobacteria and apicomplexans.
Topics: Animals; Apicomplexa; Bacteria; Bacterial Infections; Bacterial Physiological Phenomena; Cell Membrane; Host-Pathogen Interactions; Humans; Protozoan Infections; Vacuoles
PubMed: 23204363
DOI: 10.1128/MMBR.00024-12 -
PLoS Neglected Tropical Diseases Apr 2011Detailed investigations of multiparasitism are scarce in the Mekong River basin. We assessed helminth (trematode, nematode, and cestode), and intestinal protozoa...
BACKGROUND
Detailed investigations of multiparasitism are scarce in the Mekong River basin. We assessed helminth (trematode, nematode, and cestode), and intestinal protozoa infections, and multiparasitism in random population samples from three different eco-epidemiological settings in Champasack province, southern Lao People's Democratic Republic (Lao PDR), and determined underlying risk factors.
METHODOLOGY
Two stool samples were collected from 669 individuals aged ≥ 6 months over consecutive days and examined for helminth infections using the Kato-Katz method. Additionally, one stool sample per person was subjected to a formalin-ethyl acetate concentration technique for diagnosis of helminth and intestinal protozoa infections. Questionnaires were administered to obtain individual and household-level data pertaining to behavior, demography and socioeconomic status. Risk factors for hepato-biliary and intestinal parasitic infections and multiparasitism were determined using multiple logistic regressions analyses.
PRINCIPAL FINDINGS
MULTIPLE SPECIES INTESTINAL PARASITE INFECTIONS WERE COMMON: 86.6% of the study participants harbored at least two and up to seven different parasites concurrently. Regarding nematode infections, hookworm was the most prevalent species (76.8%), followed by Ascaris lumbricoides (31.7%) and Trichuris trichiura (25.0%). Regarding trematodes, Opisthorchis viverrini and Schistosoma mekongi infections were found in 64.3% and 24.2% of the participants, respectively. Infections with intestinal protozoa were rare.
CONCLUSIONS/SIGNIFICANCE
There is a pressing need to intensify and sustain helminth control interventions in the southern part of Lao PDR. Given the high prevalence with nematode and trematode infections and the extent of multiparasitism, preventive chemotherapy is warranted. This intervention should be coupled with health education and improved access to clean water and adequate sanitation to consolidate morbidity control and enhance sustainability.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Child; Child, Preschool; Comorbidity; Feces; Female; Helminthiasis; Helminths; Humans; Infant; Intestinal Diseases, Parasitic; Laos; Male; Middle Aged; Protozoan Infections; Risk Factors; Surveys and Questionnaires; Young Adult
PubMed: 21532735
DOI: 10.1371/journal.pntd.0001037 -
Lipids in Health and Disease May 2005The requirement of cholesterol for internalization of eukaryotic pathogens like protozoa (Leishmaniasis, Malaria and Toxoplasmosis) and the exchange of cholesterol along... (Review)
Review
The requirement of cholesterol for internalization of eukaryotic pathogens like protozoa (Leishmaniasis, Malaria and Toxoplasmosis) and the exchange of cholesterol along with other metabolites during reproduction in Schistosomes (helminths) under variable circumstances are poorly understood. In patients infected with some other helminthes, alterations in the lipid profile have been observed. Also, the mechanisms involved in lipid changes especially in membrane proteins related to parasite infections remain uncertain. Present review of literature shows that parasites induce significant changes in lipid parameters, as has been shown in the in vitro study where substitution of serum by lipid/cholesterol in medium and in experimental models (in vivo). Thus changes in lipid profile occur in patients having active infections with most of the parasites. Membrane proteins are probably involved in such reactions. All parasites may be metabolising cholesterol, but the exact relationship with pathogenic mechanism is not clear. So far, studies suggest that there may be some factors or enzymes, which allow the parasite to breakup and consume lipid/cholesterol. Further studies are needed for better understanding of the mechanisms involved in vivo. The present review analysis the various studies till date and the role of cholesterol in pathogenesis of different parasitic infections.
Topics: Animals; Cholesterol; Eukaryota; Humans; Oxygen; Parasitic Diseases
PubMed: 15882457
DOI: 10.1186/1476-511X-4-10 -
International Journal of Environmental... Mar 2018Improved water, sanitation and hygiene (WASH) are significant in preventing diarrhea morbidity and mortality caused by protozoa in low- and middle-income countries. Due... (Review)
Review
Improved water, sanitation and hygiene (WASH) are significant in preventing diarrhea morbidity and mortality caused by protozoa in low- and middle-income countries. Due to the intimate and complex relationships between the different WASH components, it is often necessary to improve not just one but all of these components to have sustainable results. The objective of this paper was to review the current state of WASH-related health problems caused by parasitic protozoa by: giving an overview and classification of protozoa and their effect on people's health, discussing different ways to improve accessibility to safe drinking water, sanitation services and personal hygiene behavior; and suggesting an institutional approach to ensure improved WASH. The findings indicate that and are more often identified during waterborne or water-washed outbreaks and they are less sensitive than most of the bacteria and viruses to conventional drinking water and wastewater treatment methods. There are various institutions of control and prevention of water-related diseases caused by protozoa in developed countries. Unfortunately, the developing regions do not have comparable systems. Consequently, the institutional and systems approach to WASH is necessary in these countries.
Topics: Cryptosporidiosis; Cryptosporidium; Developing Countries; Disease Outbreaks; Drinking Water; Giardia; Giardiasis; Hygiene; Sanitation; Waste Disposal, Fluid; Water Purification; Water Quality
PubMed: 29534511
DOI: 10.3390/ijerph15030495 -
Clinical Microbiology Reviews Oct 2010There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain... (Review)
Review
There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.
Topics: Africa South of the Sahara; Amoeba; Antiretroviral Therapy, Highly Active; Female; HIV Infections; Humans; Immunocompromised Host; Plasmodium; Pregnancy; Protozoan Infections; Trypanosomatina
PubMed: 20930074
DOI: 10.1128/CMR.00001-10 -
Parasite (Paris, France) 2018Giardia duodenalis, Cryptosporidium spp. and Toxoplasma gondii are protozoan parasites that have been highlighted as emerging foodborne pathogens by the Food and... (Review)
Review
Assessing viability and infectivity of foodborne and waterborne stages (cysts/oocysts) of Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii: a review of methods.
Giardia duodenalis, Cryptosporidium spp. and Toxoplasma gondii are protozoan parasites that have been highlighted as emerging foodborne pathogens by the Food and Agriculture Organization of the United Nations and the World Health Organization. According to the European Food Safety Authority, 4786 foodborne and waterborne outbreaks were reported in Europe in 2016, of which 0.4% were attributed to parasites including Cryptosporidium, Giardia and Trichinella. Until 2016, no standardized methods were available to detect Giardia, Cryptosporidium and Toxoplasma (oo)cysts in food. Therefore, no regulation exists regarding these biohazards. Nevertheless, considering their low infective dose, ingestion of foodstuffs contaminated by low quantities of these three parasites can lead to human infection. To evaluate the risk of protozoan parasites in food, efforts must be made towards exposure assessment to estimate the contamination along the food chain, from raw products to consumers. This requires determining: (i) the occurrence of infective protozoan (oo)cysts in foods, and (ii) the efficacy of control measures to eliminate this contamination. In order to conduct such assessments, methods for identification of viable (i.e. live) and infective parasites are required. This review describes the methods currently available to evaluate infectivity and viability of G. duodenalis cysts, Cryptosporidium spp. and T. gondii oocysts, and their potential for application in exposure assessment to determine the presence of the infective protozoa and/or to characterize the efficacy of control measures. Advantages and limits of each method are highlighted and an analytical strategy is proposed to assess exposure to these protozoa.
Topics: Animals; Biological Assay; Cells, Cultured; Cryptosporidiosis; Cryptosporidium; Food Parasitology; Genetic Techniques; Giardia lamblia; Giardiasis; Humans; Oocysts; Risk Assessment; Toxoplasma; Toxoplasmosis; Water
PubMed: 29553366
DOI: 10.1051/parasite/2018009 -
The impact of water crises and climate changes on the transmission of protozoan parasites in Africa.Pathogens and Global Health Sep 2018Waterborne protozoa (WBP) are important cause of several outbreaks all over the world. The report system of WBP in Africa is weak. More than one third of African... (Review)
Review
Waterborne protozoa (WBP) are important cause of several outbreaks all over the world. The report system of WBP in Africa is weak. More than one third of African countries (21/54) reported WBP with absent reports in the remaining countries (33/54). The top reported WBP were Cryptosporidium, Giardia, FLA and Entamoeba contaminating different African water resources. Other protozoa were less documented even though it is abundant and robust. More than one protozoa were detected in contaminated African water including drinking sources, a prediction index to popular epidemics and real presence of undocumented WBP outbreaks. Risk factors in Africa were observed to be abundant and multi-factorial 'socioeconomic, governmental, pathogen in water and climate change. Climate change is an important factor impacting Africa. Increasing droughts in Africa with other extreme weather events will lead to water crises. Incidence and transmission of WBP will change, with new manifested strains/species. Recognizing future consequences of water crises in Africa are important. Governments and population unity will be needed to protect against expected raise and spread of WBP diseases and water shortages.
Topics: Africa; Climate Change; Disease Transmission, Infectious; Humans; Incidence; Protozoan Infections; Risk Factors; Water; Water Pollution; Water Supply
PubMed: 30332341
DOI: 10.1080/20477724.2018.1523778 -
PloS One 2013More than 1 billion people are currently infected with soil-transmitted helminths and schistosomes. The global strategy to control helminthiases is the regular...
BACKGROUND
More than 1 billion people are currently infected with soil-transmitted helminths and schistosomes. The global strategy to control helminthiases is the regular administration of anthelmintic drugs to at-risk populations. However, rapid re-infection occurs in areas where hygiene, access to clean water, and sanitation are inadequate.
METHODOLOGY
In July 2011, inhabitants from two villages and seven hamlets of the Taabo health demographic surveillance system in south-central Côte d'Ivoire provided stool and urine samples. Kato-Katz and ether-concentration methods were used for the diagnosis of Schistosoma mansoni, soil-transmitted helminths (Ascaris lumbricoides, Trichuris trichiura, and hookworm), and intestinal protozoa. Urine samples were subjected to a filtration method for the diagnosis of Schistosoma haematobium. A questionnaire was administered to households to obtain information on knowledge, attitude, practice, and beliefs in relation to hygiene, sanitation, and defecation behavior. Logistic regression models were employed to assess for associations between questionnaire data and parasitic infections.
PRINCIPAL FINDINGS
A total of 1,894 participants had complete data records. Parasitological examinations revealed prevalences of hookworm, S. haematobium, T. trichiura, S. mansoni, and A. lumbricoides of 33.5%, 7.0%, 1.6%, 1.3% and 0.8%, respectively. Giardia intestinalis and Entamoeba histolytica/E. dispar were detected in 15.0% and 14.4% of the participants, respectively. Only one out of five households reported the presence of a latrine, and hence, open defecation was common. Logistic regression analysis revealed that age, sex, socioeconomic status, hygiene, and defecation behavior are determinants for helminths and intestinal protozoa infections.
CONCLUSIONS/SIGNIFICANCE
We found that inadequate sanitation and hygiene behavior are associated with soil-transmitted helminths and intestinal protozoa infections in the Taabo area of south-central Côte d'Ivoire. Our data will serve as a benchmark to monitor the effect of community-led total sanitation and hygiene education to reduce the transmission of helminthiases and intestinal protozoa infections.
Topics: Adolescent; Adult; Age Distribution; Animals; Child; Child, Preschool; Cote d'Ivoire; Defecation; Entamoeba histolytica; Environmental Exposure; Feces; Female; Giardia lamblia; Health Literacy; Helminthiasis; Helminths; Humans; Hygiene; Intestinal Diseases, Parasitic; Male; Prevalence; Rural Population; Sanitation; Surveys and Questionnaires; Young Adult
PubMed: 23840358
DOI: 10.1371/journal.pone.0065722 -
Enfermedades Infecciosas Y... 2009Acute gastrointestinal tract infections are among the most common infectious diseases. In the present review, the different methods of diagnosing gastrointestinal... (Review)
Review
Acute gastrointestinal tract infections are among the most common infectious diseases. In the present review, the different methods of diagnosing gastrointestinal infections caused by bacteria, viruses, and parasites are examined. Stool culture is the method of choice for diagnosing bacterial intestinal infections; however, infections caused by Clostridium difficile can be diagnosed by detection of toxins A and B in stools, and infections caused by diarrheagenic Escherichia coli by PCR detection of specific virulence factor genes harbored by several E. coli pathotypes. The techniques used to diagnose viral gastrointestinal infections include detection of viral antigens and nucleic acids. Finally, gastrointestinal infections caused by parasites can be diagnosed by testing for trophozoites and cysts of protozoa, or larvae and eggs of helminths in stools by direct microscopic examination, with concentration techniques, or by specific stains.
Topics: Adult; Aged; Animals; Child, Preschool; Cross Infection; Feces; Female; Gastroenteritis; Gastrointestinal Diseases; Humans; Infant; Intestinal Diseases, Parasitic; Male; Microbiological Techniques; Parasitology; Virology
PubMed: 19477556
DOI: 10.1016/j.eimc.2008.11.009