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Parasitology Jul 2020Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent,... (Review)
Review
Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO2, suggesting that CO2 plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO2. Here, we review the diverse responses of parasitic and free-living nematodes to CO2. We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO2 detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO2.
Topics: Ancylostomatoidea; Animals; Behavior; Caenorhabditis elegans; Carbon Dioxide; Chemotaxis; Host-Parasite Interactions; Humans; Life Cycle Stages; Nematoda; Strongyloides
PubMed: 31601281
DOI: 10.1017/S0031182019001422 -
MMW Fortschritte Der Medizin Jun 2021
Review
Topics: Ancylostomatoidea; Animals; Coronavirus; Coronavirus Infections; Hookworm Infections; Humans; Ivermectin
PubMed: 34086220
DOI: 10.1007/s15006-021-0066-6 -
Parasites & Vectors Mar 2020Hookworm infection is a major public health problem that threatens about 500 million people throughout tropical areas of the world. Adult hookworms survive for many... (Review)
Review
Hookworm infection is a major public health problem that threatens about 500 million people throughout tropical areas of the world. Adult hookworms survive for many years in the host intestine, where they suck blood, causing iron deficiency anemia and malnutrition. Numerous molecules, named excretory/secretory (ES) products, are secreted by hookworm adults and/or larvae to aid in parasite survival and pathobiology. Although the molecular cloning and characterization of hookworm ES products began 25 years ago, the biological role and molecular nature of many of them are still unclear. Hookworm ES products, with distinct structures and functions, have been linked to many essential events in the disease pathogenesis. These events include host invasion and tissue migration, parasite nourishment and reproduction, and immune modulation. Several of these products represent promising vaccine targets for controlling hookworm disease and therapeutic targets for many inflammatory diseases. This review aims to summarize our present knowledge about hookworm ES products, including their role in parasite biology, host-parasite interactions, and as vaccine and pharmaceutical targets and to identify research gaps and future research directions in this field.
Topics: Ancylostoma; Ancylostomatoidea; Animals; Antioxidants; Body Fluids; Cloning, Molecular; Female; Helminth Proteins; Hookworm Infections; Host-Parasite Interactions; Humans; Immunologic Factors; Male; Peptide Hydrolases; Protease Inhibitors; Vaccines
PubMed: 32171305
DOI: 10.1186/s13071-020-04010-8 -
Parasites & Vectors Apr 2022Little is known about the prevalence of Ancylostoma in dogs in the Caribbean. In view of the number of owned free-roaming and feral dogs within the islands and the ideal... (Review)
Review
BACKGROUND
Little is known about the prevalence of Ancylostoma in dogs in the Caribbean. In view of the number of owned free-roaming and feral dogs within the islands and the ideal subtropical climate for parasite development and environmental survival, Ancylostoma could pose a threat to the health of the dogs as well as a zoonotic risk to people.
METHODS
To determine whether generalities about Ancylostoma in dogs in the Caribbean could be made and to obtain a better understanding of the prevalence, published (Scielo, Scopus, and PubMed databases) and gray (e.g., student theses, conference presentations) literature was reviewed. Retrieved manuscripts were screened, and relevant data (year, location, dog population, method of diagnosis, positivity rate) were extracted. Data from two dog populations on St. Kitts also were included: a 2014 field study involving dogs with limited veterinary care and data from the Ross University School of Veterinary Medicine's Veterinary Clinic records for 2018-2019.
RESULTS
Fourteen manuscripts from the 1950s to 2019, representing ten of the Caribbean islands/countries and the Bahamas, were identified. Methods of diagnosing infection status ranged from simple qualitative or quantitative flotation methods to centrifugation with Sheather's sugar flotation solution or necropsy. Dog populations sampled included stray, owned free-roaming, and owned confined. Reported rates of Ancylostoma infection ranged from 10 to 91%. Studies from the last 10 years indicate positivity rates of 21 to 73%. Ancylostoma positivity rates in the St. Kitts' populations were 61% and 10% for the 2014 and 2018-2019 populations, respectively.
CONCLUSIONS
There was no indication that hookworm prevalence has changed over time in the Caribbean, and there were no obvious differences between owned and unowned dogs or free-roaming and confined dogs. The data from St. Kitts were on par with positivity rates from the other islands within the last 10 years and reflective of the impact that veterinary care, including anthelmintic treatment, is expected to have on parasites in pets. There is a clear need to expand the available data for the region and improve control programs for Ancylostoma infections to protect both canine and human health.
Topics: Ancylostoma; Ancylostomatoidea; Animals; Caribbean Region; Dog Diseases; Dogs; Feces; Humans; Parasites; West Indies
PubMed: 35449121
DOI: 10.1186/s13071-022-05254-2 -
The American Journal of Tropical... Nov 2017
Topics: Alabama; Ancylostomatoidea; Animals; Hookworm Infections; Humans; Parasites; Sanitation
PubMed: 29140235
DOI: 10.4269/ajtmh.17-0683 -
The American Journal of Tropical... May 2018
Topics: Albendazole; Ancylostomatoidea; Animals; Double-Blind Method; Farmers; Female; Hookworm Infections; Humans; Power, Psychological
PubMed: 29611502
DOI: 10.4269/ajtmh.17-0934 -
International Journal of Molecular... Mar 2021The integrin αIIbβ3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in... (Review)
Review
The integrin αIIbβ3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in signalling takes place leading to platelet spreading, platelet aggregation and thrombus formation. Bloodsucking parasites such as mosquitoes, leeches and ticks express anticoagulant and antiplatelet proteins, which represent major sources of lead compounds for the development of useful therapeutic agents for the treatment of haemostatic disorders or cardiovascular diseases. In addition to hematophagous parasites, snakes also possess anticoagulant and antiplatelet proteins in their salivary glands. Two snake venom proteins have been developed into two antiplatelet drugs that are currently used in the clinic. The group of proteins discussed in this review are disintegrins, low molecular weight integrin-binding cysteine-rich proteins, found in snakes, ticks, leeches, worms and horseflies. Finally, we highlight various oral antagonists, which have been tested in clinical trials but were discontinued due to an increase in mortality. No new αIIbβ3 inhibitors are developed since the approval of current platelet antagonists, and structure-function analysis of exogenous disintegrins could help find platelet antagonists with fewer adverse side effects.
Topics: Actins; Ancylostoma; Animals; Binding Sites; Blood Platelets; Diptera; Disintegrins; Drug Design; Fibrinolytic Agents; Humans; Ligands; Platelet Activation; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Platelet Glycoprotein GPIIb-IIIa Complex; Signal Transduction; Snake Venoms; Snakes; Thrombosis
PubMed: 33806083
DOI: 10.3390/ijms22073366 -
PLoS Neglected Tropical Diseases Dec 2021In 1896, a serendipitous laboratory accident led to the understanding that hookworms propagate infection by penetrating skin, a theory that was then confirmed with the... (Review)
Review
In 1896, a serendipitous laboratory accident led to the understanding that hookworms propagate infection by penetrating skin, a theory that was then confirmed with the first experimental human infection, reported in 1901. Experimental human infections undertaken in the 20th century enabled understanding of the natural history of infection and the immune response. More recently, experimental hookworm infection has been performed to investigate the immunomodulatory potential of hookworm infection and for the evaluation of hookworm vaccines and chemotherapeutic interventions. Experimental human hookworm infection has been proven to be safe, with no deaths observed in over 500 participants (although early reports predate systematic adverse event reporting) and no serious adverse events described in over 200 participants enrolled in contemporary clinical trials. While experimental human hookworm infection holds significant promise, as both a challenge model for testing anti-hookworm therapies and for treating various diseases of modernity, there are many challenges that present. These challenges include preparation and storage of larvae, which has not significantly changed since Harada and Mori first described their coproculture method in 1955. In vitro methods of hookworm larval culture, storage, and the development of meaningful potency or release assays are required. Surrogate markers of intestinal infection intensity are required because faecal egg counts or hookworm faecal DNA intensity lack the fidelity required for exploration of hookworm infection as a vaccine/drug testing platform or as a regulated therapy.
Topics: Ancylostomatoidea; Animals; Antigens, Helminth; Feces; Female; History, 19th Century; History, 20th Century; History, 21st Century; Hookworm Infections; Human Experimentation; Humans; Research; Vaccines
PubMed: 34882670
DOI: 10.1371/journal.pntd.0009908 -
International Journal For Parasitology Dec 2021The major soil-transmitted helminths that infect humans are the roundworms, whipworms and hookworms. Soil-transmitted helminth infections rank among the most important... (Review)
Review
The major soil-transmitted helminths that infect humans are the roundworms, whipworms and hookworms. Soil-transmitted helminth infections rank among the most important neglected tropical diseases in terms of morbidity, and almost one billion people are still infected with at least one species. While anthelmintic drugs are available, they do not offer long term protection against reinfection, precipitating the need for vaccines that provide long-term immunologic defense. Vaccine discovery and development is in advanced clinical development for hookworm infection, with a bivalent human hookworm vaccine in clinical trials in Brazil and Africa, but is in its infancy for both roundworm (ascariasis) and whipworm (trichuriasis) infections. One of the greatest hurdles to developing soil-transmitted helminth vaccines is the potent immunoregulatory properties of these helminths, creating a barrier to the induction of meaningful long-term protective immunity. While challenging for vaccinologists, this phenomenon presents unique opportunities to develop an entirely new class of anti-inflammatory drugs that capitalise on these immunomodulatory strategies. Epidemiologic studies and clinical trials employing experimental soil-transmitted helminth challenge models, when coupled with findings from animal models, show that at least some soil-transmitted helminth-derived molecules can protect against the onset of autoimmune, allergic and metabolic disorders, and several natural products with the desired bioactivity have been isolated and tested in pre-clinical settings. The yin and yang of soil-transmitted helminth infections reflect both the urgency for effective vaccines and the potential for new immunoregulatory molecules from parasite products.
Topics: Ancylostomatoidea; Animals; Ascariasis; Helminthiasis; Helminths; Hookworm Infections; Humans; Nematoda; Prevalence; Soil; Trichuriasis; Trichuris; Vaccines
PubMed: 34774540
DOI: 10.1016/j.ijpara.2021.11.001 -
International Journal For Parasitology.... Dec 2018Infection with gastrointestinal parasitic nematodes is a major cause of chronic morbidity and economic burden around the world, particularly in low-resource settings.... (Review)
Review
Infection with gastrointestinal parasitic nematodes is a major cause of chronic morbidity and economic burden around the world, particularly in low-resource settings. Some parasitic nematode species, including the human-parasitic threadworm Strongyloides stercoralis and human-parasitic hookworms in the genera Ancylostoma and Necator, feature a soil-dwelling infective larval stage that seeks out hosts for infection using a variety of host-emitted sensory cues. Here, we review our current understanding of the behavioral responses of soil-dwelling infective larvae to host-emitted sensory cues, and the molecular and cellular mechanisms that mediate these responses. We also discuss the development of methods for transgenesis and CRISPR/Cas9-mediated targeted mutagenesis in Strongyloides stercoralis and the closely related rat parasite Strongyloides ratti. These methods have established S. stercoralis and S. ratti as genetic model systems for gastrointestinal parasitic nematodes and are enabling more detailed investigations into the neural mechanisms that underlie the sensory-driven behaviors of this medically and economically important class of parasites.
Topics: Ancylostoma; Ancylostomiasis; Animals; Gastrointestinal Diseases; Host-Parasite Interactions; Humans; Larva; Necator; Nematoda; Nematode Infections; Rats; Sensation; Soil; Strongyloides ratti; Strongyloides stercoralis
PubMed: 30396862
DOI: 10.1016/j.ijpddr.2018.10.008