Clinical Toxicology of Tick Bites
Jürg Meier, Julian White in 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)
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2015
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).
Omsk Hemorrhagic Fever and Kyasanur Forest Disease
James H. S. Gear in 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.
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.
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).
The knowns and unknowns of West Nile virus in Europe: what did we learn from the 2018 outbreak?
Published in Expert Review of Anti-infective Therapy, 2020
Jeremy V Camp, Norbert Nowotny
West Nile virus (‘WNV’, Family Flaviviridae) is a remarkable virus. First isolated from a febrile patient in Uganda (1937) and later from mosquitoes, birds, and human patients in Egypt (1950s), its success as a ‘generalist’ arbovirus has since been well documented [1,2,3]. Perhaps owing to the large number of organisms the virus can infect – mosquitoes (Diptera: Culicidae), hard and soft ticks (Acari: Ixodidae and Argasidae), birds, reptiles, amphibians, and mammals – the virus has spread throughout the globe [1]. After sporadic outbreaks in Africa and Eurasia in the 60 years following its first isolation, the last 20 years have seen the (re)emergence of WNV on every continent except Antarctica and the increased frequency of outbreaks in humans, birds, and horses [2].