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Omsk Hemorrhagic Fever and Kyasanur Forest Disease
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The cycle of KFD virus is also markedly influenced by manmade factors. It first manifested itself by an abnormal mortality among monkeys, i.e., Presbytis entellus ana Macaca radiata, in Kyasanur Forest. Since then, the disease has become known in the enzootic areas as “monkey disease,” justifiably so, in view of the decimation it has continually caused among monkeys in affected areas. It remains a matter for speculation whether this was a new disease or whether it had occurred but failed to be recognized before. The chief vectors are juvenile ticks of the genus Haemaphysalis and Ixodes, although only the former genus is important in the transmission of the virus to man. Argasid ticks have also been found infected.
Clinical Toxicology of Tick Bites
Published in Jürg Meier, Julian White, Handbook of: Clinical Toxicology of Animal Venoms and Poisons, 2017
Ticks are invertebrates, members of the class Arachnida, subclass Acari, order Meostigmata. They have 4 pairs of walking legs and no antennae, a feeding device (hypostoma) and are all ectoparasites of terrestrial vertebrates, particularly mammals. Ticks of medical importance are found in two distinct families; Ixodidae (hard ticks) and Argasidae (soft ticks). The Ixodid ticks are in the majority (at least 644 species2). They have a hard body plate, or cuticle, unlike the Argasid ticks (at least 149 species2), the cuticle of which is not rigid, and “leathery”. Argasid ticks feed, then drop off the host, the feeding process often taking only 5 to 25 mins. In contrast, Ixodid ticks in the adult phase (females) may remain attached to the host, feeding, for a considerably longer period of time, up to 11 days, possibly more. In general, it appears that the longer the period of attachment, the more likely is paralysis. Tick paralysis is a phenomenon associated with Ixodid ticks, and the following description of feeding biology relates to this group.
Ticks (order Ixodida)
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Hosts and transmission Although they may have preferred hosts, most ixodid ticks feed opportunistically on a wide range of hosts (Figure 3). Because they are generalist feeders and because they are competent vectors for many pathogens, they are important in the transmission of many viral, bacterial, and protozoan pathogens to humans and domestic animals. A few of the diseases transmitted by ixodid ticks as well as the principal genera of vectors include: Lyme disease, Theileria microti and ehrlichiosis (transmitted by members of genus Ixodes); tularemia and Rocky Mountain spotted fever (genus Dermacentor and genus Amblyomma); East Coast fever (Theileria parva) in cattle (genus Rhipicephalus); Crimean-Congo hemorrhagic fever (genus Hyalomma); and Babesia bigemina, the cattle disease red water fever (genus Rhipicephalus (Boophilus)). Argasid ticks in the genus Ornithodoros may transmit relapsing fever (Borrelia hermsi).
Additional considerations for anti-tick vaccine research
Published in Expert Review of Vaccines, 2022
José de la Fuente, Marinela Contreras
Recent publications and particularly a recent paper by Ndawula, Jr [1]. provided a comprehensive review on anti-tick vaccine research and results. In this review, the author addressed the limitations in tick vaccine research with emphasis on the methodology for the evaluation of vaccine efficacy and effectiveness and the need to advance in the characterization of the immunological mechanisms mediating vaccine efficacy for the control of both ixodid and argasid tick infestations. We agree on this proposal for the evaluation of vaccine efficacy and effectiveness. However, additional considerations disclosed here using our research based on the Subolesin tick antigen model are relevant for the development of effective and safe vaccines for the control of tick infestations and tick-borne diseases (TBD).
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
Previous reports based only on the detection of viral RNA from tick specimens collected while feeding on infested hosts may be regarded as preliminary until additional evidences are provided. It has been demonstrated that soft ticks (family Argasidae) cannot transmit the virus [45]. Ticks are considered to be both reservoirs and vectors of the virus because of the short period of viremia observed in vertebrates. In this context, the co-feeding transmission seems to be a very efficient route, together with the transovarial transmission of the virus from engorged ticks to eggs [46]. Co-feeding transmission is a special mechanism of virus circulation in which infected ticks, feeding together with uninfected ones, can transmit the virus to the naïve ticks that feed on the same ‘pool.’ Ticks tend to be highly aggregated on the skin of the hosts and therefore the opportunities for the virus to enter the feeding pool and infect co-feeding ticks are high.
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
During the last two decades, the rate of emergence of vector-borne diseases has increased worldwide presenting a significant global economic burden. Ticks are second only to insects as vectors of human diseases, and are the most important vectors of livestock diseases especially in tropical countries [1]. Ticks, hematophagous ectoparasitic arthropods belonging to the order Ixodida of the class Arachnida, comprise two main families: the Argasidae (soft ticks) with 218 species [2] and the Ixodidae (hard ticks) with 742 species [3]. Ticks are widely distributed around the world, in particular in countries with warm, humid climates. As obligate bloodfeeders, ticks can acquire a variety of pathogenic bacteria, viruses, protozoa, and helminths from their hosts during feeding [4], and subsequently transmit the pathogens during their next blood meal. Once infected, ticks may remain infective for a single stage or for life, depending on the pathogen species, and can transmit to vertebrate hosts and/or other ticks. Other ticks may be infected by the venereal route or by co-feeding in which the pathogen transmission occurs when a naïve tick acquires an infection after feeding in close proximity to an infected tick while the vertebrate host may remain uninfected [5]. In addition, numerous tick-borne pathogens can be passed vertically from adult females to their offspring, which can then transmit during their first or subsequent blood meal. Although the vertical transmission efficiency appears to be low for some microorganisms, it is essential for the persistence of pathogens for which ticks also represent the natural reservoir [6].