Ticks
Gail Miriam Moraru, Jerome Goddard in The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
The term tick-borne encephalitis (TBE) is generally used to describe disease entities caused by at least three subtypes of a flavivirus: European tick-borne encephalitis (TBEV-Eur), Siberian (TBEV-Sib), and Far Eastern (TBEV-FE). A couple of these agents, however, occur in the Western Hemisphere (see below). The three Old World TBE diseases differ in severity, with the Far Eastern form, sometimes known as Russian spring–summer encephalitis (RSSE), being the worst. In Central Europe, the typical case shows a biphasic course with an early, viremic, flulike stage, followed about a week later by the appearance of signs of meningoencephalitis.82 CNS disease is relatively mild, but occasional severe motor dysfunction and permanent disability occur. The case fatality rate is 1 to 5%.83 On the other hand, TBEV-FE is characterized by violent headache, high fever, nausea, and vomiting. Delirium, coma, paralysis, and death may follow; the mortality rate is about 25 to 30%. A recent report showed that new variants of TBE virus in Russia may produce a hemorrhagic syndrome.84,85 Another member of the TBE serocomplex is called louping ill—named after a Scottish sheep disease—which, in humans, also displays a biphasic pattern and is generally mild. As mentioned, the virus infects sheep; few cases are actually ever reported in humans.
Scrapie in Britain, 1730–1960
Kiheung Kim in The Social Construction of Disease, 2006
During the 1940s and 1950s, the Moredun Institute conducted a variety of research projects on scrapie, and brought to light some puzzling features of the disease. David Wilson's work and the louping-ill vaccine incident provided valuable experimental data for subsequent researchers, and valuable primary knowledge for the understanding of the disease. Furthermore, in the 1950s, the ARC decided to set up new research programmes on scrapie in Edinburgh and Compton. These projects would produce valuable results and controversial hypotheses. During the 1960s, the newly launched large-scale programmes in the UK produced valuable research outcomes and speculations. As we shall discuss in Chapter 3, the two research teams suggested quite opposite and con-flicting ideas about the nature of the disease. Although the research programmes discovered the unusual properties of scrapie, which could help to understand the mechanism of the disease, the relations between the two centres quickly became strained, and eventually led to open controversy and rivalry during the 1960s and 1970s.
Toxoplasma gondii
Peter D. Walzer, Robert M. Genta in Parasitic Infections in the Compromised Host, 2020
Acute and chronic infection with Toxoplasma have paradoxical effects on the cell-mediated immune system. Chronic infection with Toxoplasma confers upon mice nonspecific resistance to a variety of intracellular pathogens and to transplantable and autochthonous tumors. However, acute and chronic infection with Toxoplasma also appear to have a profound immunosuppressive effect on other immunological functions. Strickland et al. (146) and Huldt (147) demonstrated that the primary humoral response to immunization with sheep red blood cells in mice chronically infected with Toxoplasma was depressed compared with uninfected controls. In addition, Huldt et al. noted severe atrophy of the thymus associated with acute infection (148). Hibbs et al. (149) also showed that chronically infected mice that were reinfected with the same strain of Toxoplasma had a suppressed primary antibody response to sheep red blood cells and to tetanus toxoid; however, the secondary antibody response to both sheep red blood cells and tetanus toxoid remained intact. In addition, primary humoral response in mice to Clostridium welchii typhii vaccine, louping ill virus vaccine, bovine serum albumin, and live louping ill virus has been depressed in mice with Toxoplasma (150). Buxton et al. (151) demonstrated that the antibody response to enzootic abortion vaccine and louping ill vaccine was significantly depressed in sheep infected for 7 or 28 days with Toxoplasma compared with uninfected controls.
Interactomics and tick vaccine development: new directions for the control of tick-borne diseases
Published in Expert Review of Proteomics, 2018
Sara Artigas-Jerónimo, José De La Fuente, Margarita Villar
Vaccines represent one of the biggest advances regarding the improvement of human and animal health. In the last years, vaccines have been shown to be the most efficient, cost-effective, and environmentally friendly approach for the control of ticks and the prevention of TBDs, especially in regions with high risk of infection or with severe disease symptoms [4,19]. Unfortunately, mainly due to safety issues to date only tick vaccines based on cattle tick, Rhipicephalus microplus, BM86 or BM95 recombinant antigens have been commercialized for the control of tick infestations showing a dual effect on reducing the prevalence of several TBDs in cattle [20–22]. Other potential recombinant antigens have been identified and tested showing a variable range of protective efficacy against different tick species, but the effect on pathogen infection and transmission has been only reported in few of them [4,23–25]. Moreover, vaccines for the control of some of the most dangerous and widespread TBDs, such as tick-borne encephalitis, Spanish goat encephalitis, Lyme disease or borreliosis, Louping ill, and Crimean-Congo hemorrhagic fever, have been developed with various efficacy and safety ranges [26–29].
Low prevalence of tick-borne encephalitis virus antibodies in Norwegian blood donors
Published in Infectious Diseases, 2021
Åshild Marvik, Yngvar Tveten, Anne-Berit Pedersen, Karin Stiasny, Åshild Kristine Andreassen, Nils Grude
Interference caused by flavivirus cross-reactive antibodies, due to common antigenic sites within the E protein, is well documented with the ELISA method among several flaviviruses that infect humans, like Japanese encephalitis virus, dengue virus and yellow fever virus [38,43–45]. A comparative study of different commercial TBEV IgG-ELISA kits, including Enzygnost, revealed particularly specificity problems with dengue virus IgG [45]. In the current study, exposure to other flaviviruses, either through vaccination or undergone infections, were obtained. Two of the three donors with a history of dengue fever had a reactive TBEV IgG ELISA due to cross-reactivity. In addition, at least two other donors had a reactive ELISA due to vaccination against Japanese encephalitis and/or yellow fever. Thus, at least four cases of flavivirus cross-reactive antibodies were observed. Skarpaas et al. did not assess false-positive TBEV IgG ELISA results due to any flavivirus exposure, while Thortveit et al. obtained information about TBE and/or yellow fever vaccinations. According to the literature, and our observations, a history of dengue fever is an important flavivirus exposure to identify. Louping-ill virus (LIV) is another flavivirus transmitted by I. ricinus ticks and is antigenically closely related to TBEV [44]. LIV can cause encephalomyelitis of sheep and is mainly restricted to the British Isles. However, LIV infections in sheep have been reported in Norway although the last case was in 1991 [46,47]. LIV is a rare cause of human disease and no human cases have ever been reported in Norway [48]. Thus, at present, cross-reactivity due to LIV antibodies is not a current issue.
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