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At least 847 records · Page 47Linked to original sources
PubMed1996

Cytokine control of parasite-specific anergy in human urinary schistosomiasis. IL-10 modulates lymphocyte reactivity.

Humans chronically infected with schistosomiasis usually have impaired parasite Ag-specific lymphocyte proliferation and IFN-gamma production that may facilitate persistence of the parasite while producing little clinical disease. The mechanisms that contribute to the immunologic hyporesponsiveness in these patients remain undefined. IL-10 has been shown to exert an inhibitory effect on cell-mediated immunity. To determine whether endogenous IL-10 has a role in regulating parasite-specific anergy in schistosomiasis, neutralizing anti-IL-10 added to PBMC from Schistosoma haematobium patients' enhanced adult worm (SWAP)- or egg Ag (SEA)-driven lymphocyte proliferation and/or IFN-gamma production by 2- to >100-fold in 32 of 38 subjects. In contrast, anti-IL-10 failed to significantly augment the mycobacterial Ag, purified protein derivative (PPD)-driven lymphocyte proliferation, or IFN-gamma production in 9 or 10 of 14 individuals, respectively. SWAP or SEA triggered IL-10 release from PBMC of both patients and healthy individuals; however, CD4+ cells were a significant source of IL-10 only in infected subjects. PPD relative to SWAP induced fivefold less IL-10 release by CD4+ cells (p < 0.01). A possible mechanism whereby IL-10 suppressed Ag-specific T cell responses was demonstrated by the ability of SWAP and not PPD to suppress B7 expression on PBMC. Anti-IL-10 completely inhibited the parasite Ag-induced down-regulation of B7 expression. These studies indicate that IL-10 contributes to parasite Ag-induced T cell hyporesponsiveness observed in patients with chronic schistosomiasis hematobia.

Adolescent↗
PubMed2006

From discovery to development: current industry perspectives for the development of novel methods of helminth control in livestock.

Despite the extraordinary success in the development of anthelmintics in the latter part of the last century, helminth parasites of domestic ruminants continue to pose the greatest infectious disease problem in grazing livestock systems worldwide. Newly emerged threats to continuing successful livestock production, particularly with small ruminants, are the failure of this chemotherapeutic arsenal due to the widespread development of anthelmintic resistance at a time when the likelihood of new products becoming commercially available seems more remote. Changing public attitudes with regards to animal welfare, food preferences and safety will also significantly impact on the ways in which livestock are managed and their parasites are controlled. Superimposed on this are changes in livestock demographics internationally, in response to evolving trade policies and demands for livestock products. In addition, is the apparently ever-diminishing numbers of veterinary parasitology researchers in both the public and private sectors. Industries, whether being the livestock industries, the public research industries, or the pharmaceutical industries that provide animal health products, must adapt to these changes. In the context of helminth control in ruminant livestock, the mind-set of 'suppression' needs to be replaced by 'management' of parasites to maintain long-term profitable livestock production. Existing effective chemical groups need to be carefully husbanded and non-chemotherapeutic methods of parasite control need to be further researched and adopted, if and when, they become commercially available. This will require veterinary parasitology researchers from both the public and private sectors to work in close co-operation to ensure 'sustainability' - not only of the livestock industries that they service - but also for their very own activities and enterprises.

Animal Welfare↗
PubMed2002

Resistance to antiparasitic drugs: the role of molecular diagnosis.

Chemotherapy is central to the control of many parasite infections of both medical and veterinary importance. However, control has been compromised by the emergence of drug resistance in several important parasite species. Such parasites cover a broad phylogenetic range and include protozoa, helminths and arthropods. In order to achieve effective parasite control in the future, the recognition and diagnosis of resistance will be crucial. This demand for early, accurate diagnosis of resistance to specific drugs in different parasite species can potentially be met by modern molecular techniques. This paper summarises the resistance status of a range of important parasites and reviews the available molecular techniques for resistance diagnosis. Opportunities for applying successes in some species to other species where resistance is less well understood are explored. The practical application of molecular techniques and the impact of the technology on improving parasite control are discussed.

Animals↗
PubMed1986

[Controllable infections and the self-regulation of parasitic systems].

The control of the epidemic process is based on the knowledge of the mechanisms of self-regulation, developed in the process of evolution, in the relationship of the host and parasite populations under the changing conditions of the social and natural environment. The problem of the global and regional liquidation of infections controllable by means of immunoprophylactic measures is considered.

Animals↗
PubMed1994

[Ectoparasites of animals: methods of ecological, biological, genetic and mechanical control].

The use of insecticides is still the basic procedure for controlling most ectoparasites, but various methods are being developed to act in addition to, or in synergy with these products, so as to enhance the efficacy and reduce the adverse effects of insecticides, by contributing to ecologically acceptable strategies. These methods are classified as ecological control (modification of the environment of the parasite), biological control (predation, parasitism, action of pathogens, etc.), genetic control (release of sterile males, hybridisation, genetic manipulations) and mechanical control (insect traps, use of repellents). The application of such methods depends on the biological and ecological characteristics of the ectoparasite, and they may act directly or indirectly, affecting mortality and/or reproduction. The authors review the principal methods applicable to major groups of ectoparasites of veterinary interest. Non-chemical methods are the subject of wide-ranging and promising research, particularly in view of recent developments in biotechnology.

Animals↗
PubMed1989

Man and his parasites: integration of biomedical and social approaches to transmission and control.

The significance of sociocultural and behavioural factors in the transmission and control of parasitic infections has been underestimated. Explanations for this neglect include the failure of communication between biomedics and social scientists and reliance on control measures such as mass chemotherapeutic and anti-vector programmes which do not involve the participation of the community at risk. The need for an integrated approach to both the impact of parasitic infections and their control is now being recognised. Given their very high prevalence and the background socio-economic and other factors which exacerbate the problem, parasites of the subtropical and tropical countries will be the main emphasis of this discussion. The paper will illustrate a number of methodologies employed to look at the relationship between sociocultural and parasitic infections rather than provide a catalogue of interesting and yet isolated examples of human risk behaviours. These methodologies will include assessments of both individual risk factors and a broader framework to include larger social groupings including 'outsiders' involved in control programmes. Finally, the importance of this type of emphasis within control strategies will be discussed and a concluding section on research priorities and recommendations will be presented.

Cultural Characteristics↗
PubMed1985

Research needs and priorities for swine internal parasites in the United States.

The swine industry in the United States is increasing in the Southeast. The proportion of pigs raised in confinement has increased to 25% and the trend is expected to continue. Changes in geographic origin and in management have affected the swine parasite fauna. A few parasites have almost disappeared and others have gained new prominence. Prevention and control of parasites are accomplished by feed additives and routine therapeutic treatments. Knowledge of the epizootiologic factors governing parasite transmission, in relation to climate and management systems, may lead to improvements in the prevention and control of swine parasites. Opportunities exist for developing biological, chemical, and managerial practices that can be integrated economically into management systems to control parasites and improve performance through decreases in mortality and morbidity and increases in daily gain and feed conversion efficiency.

Animal Husbandry↗
PubMed2003

Trypanosoma cruzi infection: a continuous invader-host cell cross talk with participation of extracellular matrix and adhesion and chemoattractant molecules.

Several lines of evidence have shown that Trypanosoma cruzi interacts with host extracellular matrix (ECM) components producing breakdown products that play an important role in parasite mobilization and infectivity. Parasite-released antigens also modulate ECM expression that could participate in cell-cell and/or cell-parasite interactions. Increased expression of ECM components has been described in the cardiac tissue of chronic chagasic patients and diverse target tissues including heart, thymus, central nervous system and skeletal muscle of experimentally T. cruzi-infected mice. ECM components may adsorb parasite antigens and cytokines that could contribute to the establishment and perpetuation of inflammation. Furthermore, T. cruzi-infected mammalian cells produce cytokines and chemokines that not only participate in the control of parasitism but also contribute to the establishment of chronic inflammatory lesions in several target tissues and most frequently lead to severe myocarditis. T. cruzi-driven cytokines and chemokines may also modulate VCAM-1 and ICAM-1 adhesion molecules on endothelial cells of target tissues and play a key role in cell recruitment, especially of activated VLA-4+LFA-1+CD8+ T lymphocytes, resulting in a predominance of this cell population in the inflamed heart, central nervous system and skeletal muscle. The VLA-4+-invading cells are surrounded by a fine network of fibronectin that could contribute to cell anchorage, activation and effector functions. Since persistent "danger signals" triggered by the parasite and its antigens are required for the establishment of inflammation and ECM alterations, therapeutic interventions that control parasitism and selectively modulate cell migration improve ECM abnormalities, paving the way for the development of new therapeutic strategies improving the prognosis of T. cruzi-infected individuals.

Animals↗
PubMed2004

Immune responses to fleas in two rodent species differing in natural prevalence of infestation and diversity of flea assemblages.

We studied in vivo immune response to fleas in two gerbils, Gerbillus dasyurus and Gerbillus andersoni allenbyi, which differed in their natural species richness of flea assemblages and prevalence of infestation. G.dasyurus is parasitized naturally by several flea species, but the prevalence of infestation is low, whereas G. a. allenbyi is parasitized by a single flea species, with high prevalence of infestation. We hypothesized that immunological parameters and the cell-mediated specific immune response to an antigen from an unfamiliar flea species differ between the two gerbil species. Parasitized and control gerbils of both species demonstrated similar, relatively low levels of spontaneous glucose consumption. The same was true for the phytohemagglutinin treatment. Responses to antigen from unfamiliar flea species were higher than both spontaneous glucose consumption and response to phytohemagglutinin in parasitized and control G. a. allenbyi and parasitized G. dasyurus. However, no significant difference in the spontaneous blast transformation index and responses to both phytohemagglutinin and flea antigen was found in control G. dasyurus. The number of white blood cells was significantly lower in control than in parasitized G. dasyurus, whereas no difference in the number of white blood cells was found between control and parasitized G. a. allenbyi. The levels of circulating immune complexes and concentrations of immunoglobulins did not differ between parasitized and control individuals in both species. Phagocytic activity was significantly higher in males than in females of G. a. allenbyi but not of G. dasyurus. In addition, phagocytes of G. dasyurus appeared to be significantly more active than those of G. a. allenbyi.

Animals↗
PubMed1989

History of veterinary parasitology in France.

The history of veterinary parasitology in France can be divided into three parts. (1) The early period of veterinary education, and development of sections on parasites and parasitic diseases, immediately following the creation of the veterinary colleges in France in 1762-1765 by Cl. Bourgelat until the beginning of the 19th century. This was the period of academics, naturalists and zoologists, with the exception of P. Chabert who, as early as 1782, directed attention to the harmful effects of parasites on animals and tried to control them. (2) Identification and establishment of the field of veterinary parasitology and the development of specific research work, mostly in veterinary colleges, on the biology and systematic control of parasites. This period was dominated by the tremendous amount of work carried out by L.G. Neumann and A. Railliet in every topic of veterinary parasitology. (3) The modern period of veterinary parasitology (before and after World War II). This period is characterized by the increasing development of the most sophisticated techniques in fundamental and applied research to provide efficient cheap and practical means for the diagnosis and control of parasitic diseases in animals.

Animals↗