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Ticks
Published in Jerome Goddard, Public Health Entomology, 2022
Tick paralysis. Tick paralysis is characterized by an acute, ascending, flaccid motor paralysis that may terminate fatally if the tick is not located and removed. The causative agent is believed to be a salivary toxin produced by ticks when they feed. Many hard tick species may be involved, but Dermacentor andersoni, D. variabilis, and Ixodes holocyclus are notorious offenders. The disease is especially common in Australia. In North America, hundreds of cases have been documented from the Montana–British Columbia region.21,22 Tick paralysis may occur in the southeastern United States as well. The author has seen two documented cases in young children admitted to the University of Mississippi Medical Center in Jackson, MS. Sporadic cases may occur elsewhere, such as Europe, Africa, and South America.
Diagnostic Approach to Rash and Fever in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Lee S. Engel, Charles V. Sanders, Fred A. Lopez
Rocky Mountain spotted fever, the most lethal rickettsial disease in the United States, is caused by Rickettsia rickettsii [31–36]. Infection occurs approximately 7 days after a bite by a tick vector (Dermacentor or Rhipicephalus). As of 2010, cases of RMSF are reported as spotted fever rickettsiosis (SFR) to capture cases of RMSF, R. parkeri rickettsiosis, Pacific Coast tick fever, and rickettsialpox [37]. The incidence of SFR has increased since 2000 from 495 reported cases to 4269 reported cases in 2016 [38]. Patients who have frequent exposure to dogs and live near wooded areas or areas with high grass may be at an increased risk of infection. The RMSF is more common in men and is most prevalent in the southern Atlantic and southern central states. North Carolina and Oklahoma are the states with the highest incidence, accounting for over 35% of the cases. Greater than 90% of patients are infected between April and September. During this season, there are increased numbers of ticks. Furthermore, research has demonstrated a link between warmer temperatures and increased tick aggressiveness [39].
Unexplained Fever In Infectious Diseases: Section 2: Commonly Encountered Aerobic, Facultative Anaerobic, And Strict Anaerobic Bacteria, Spirochetes, And Parasites
Published in Benedict Isaac, Serge Kernbaum, Michael Burke, Unexplained Fever, 2019
Babesiosis is a disease which often evolves with fever. It is caused by intraerythroeitic protozoan parasites of the genus Babesia. This infection is common in both domestic and wild animals. The parasite is transmitted from animal to man by the bite of ticks (of the genera Ixodes, Dermacentor, Rhipicephalus). The most important causative agents are bovine parasites (B. bovis, B. divergens) or rodent parasites (B. microti). Babesiosis should be considered in any patient with fever, a history of tick bite, a prior splenectomy, a blood transfusion, or sojourn in endemic areas (in U.S.: Nantucket, Massachusetts, New York, Long Island Sound; in Europe: Yugoslavia, USSR, France, Scotland, Ireland). An associated hemolytic anemia is very suggestive.117
How relevant are in vitro culture models for study of tick-pathogen interactions?
Published in Pathogens and Global Health, 2021
Cristiano Salata, Sara Moutailler, Houssam Attoui, Erich Zweygarth, Lygia Decker, Lesley Bell-Sakyi
An interesting study compared the ability to phagocytose and destroy live B. burgdorferi s.s. spirochetes of vector (IDE12 and ISE6) and non-vector (DAE15) tick cell lines [162]. IDE12 and DAE15 cells were highly phagocytic, with over 80% of cells containing spirochetes after 24 h, while with ISE6 cells the spirochetes remained extracellular and appeared viable. DAE15 cells phagocytosed spirochetes faster and in higher numbers than IDE12 cells. The ability of the non-vector D. andersoni DAE15 cells to rapidly ingest and destroy B. burgdorferi in vitro [162] reflects the reported ability of non-vector Dermacentor variabilis ticks to destroy inoculated spirochetes using both cellular and humoral responses [163]. More recently, siRNA-mediated RNAi transcript knockdown in ISE6 cells and in I. scapularis and D. andersoni ticks was used to examine the role of components of the tick IMD pathway in infection with B. burgdorferi s.s., A. phagocytophilum and A. marginale [133]. Good agreement was obtained between the in vitro ISE6 model and live, intact ticks inoculated with siRNAs for several IMD pathway genes identified as having positive or negative effects on replication of all three pathogens.
Management strategies for human babesiosis
Published in Expert Review of Anti-infective Therapy, 2020
Robert P. Smith, Klaus-Peter Hunfeld, Peter J Krause
Babesia duncani is the second most important cause of human babesiosis in the US after B. microti, although less than 20 cases have been reported [113]. Recent epidemiological studies provide evidence that the tick vector is Dermacentor albipictus. The reservoir host is likely the mule deer (Odocoileus hemionus) whose broad occurrence covers a large portion of far-western North America [114] B. duncani also can be transmitted through blood transfusion [12,66,115]. B. duncani causes an array of disease severity from asymptomatic infection to fatal disease [12,13,62,108,115]. An in vitro B. duncani human red blood cell culture system demonstrated low susceptibility to standard agents such as atovaquone, azithromycin, clindamycin, and quinine [116]. Clinical experience with treatment of infection due to B. duncani with a course of clindamycin and either quinine or quinidine is limited but generally successful [12,13,115]. In one case, symptoms relapsed and the patient was successfully treated with high dose intravenous clindamycin and oral quinine. In severe cases, red blood cell exchange transfusion and hemodialysis have been instituted [12,13,115,117].
Modeling tick vaccines: a key tool to improve protection efficacy
Published in Expert Review of Vaccines, 2020
José de la Fuente, Agustin Estrada-Peña, Marinela Contreras
In this section, we will use as a proof-of-concept the development of vaccination strategies for the control of a potentially lethal tick-borne zoonosis: the Crimean-Congo hemorrhagic fever (CCHF) transmitted by ticks of the genus Hyalomma. The CCHF affects humans and is caused by the Orthonairovirus CCHF virus (CCHFv) transmitted mainly by tick bites but also by sprays from infected animals (i.e. at abattoirs) [19–21]. The virus has the widest known worldwide distribution of any tick-transmitted virus [45]. Additionally, laboratory studies demonstrated that other tick species of the genera Rhipicephalus and Dermacentor could also be involved in the natural cycle of the virus [45]. The CCHFv is a paradigm in vaccinology due to ongoing efforts to develop vaccines applied to vertebrate animal hosts (and not to humans) and because the challenge that poses to effective vaccination schemes the dual life cycle of the tick vectors (immatures feeding on small animals and adults on ungulates). Additionally, discussions exist about the suitability to include in the same scheme a combination of anti-viral and anti-tick vaccines.