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Ticks
Published in Jerome Goddard, Public Health Entomology, 2022
Spotted fever group rickettsioses. Ticks may transmit a wide variety of rickettsial organisms, classified by scientists into several distinct groups. One of the main groups, the spotted fever group (SFG), contains rickettsial species related to the agent of Rocky Mountain spotted fever (RMSF), Rickettsia rickettsii. But there are many other rickettsial species in the SFG (Figure 10.10); it contains at least 8 disease agents and 15 others with low or no pathogenicity to humans. RMSF is the most frequently reported rickettsial disease in the United States, with several thousand cases reported each year. In 2018, there were 5,544 cases of spotted fever rickettsiosis reported in the United States.4 At the time of initial presentation, there is often the classic triad of RMSF: fever, headache, and rash (Figure 10.11). Other characteristics are malaise, chills, myalgias, and gastrointestinal symptoms. Sometimes RMSF leads to coma and death, and the mortality rate is about 5% even with treatment.
Encephalitis and Its Mimics in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Patients with rickettsia (particularly Rocky Mountain spotted fever [RMSF]) and ehrlichia/anaplasma (particularly human monocytic and granulocytic ehrlichiosis) infected patients can have severe headaches and prominent mental status changes. In both, the disorder caused by these intracellular organisms probably is less an encephalitis than an infectious vasculitis. Rocky Mountain spotted fever in particular can be associated with significant cerebral edema and stupor. Cerebrospinal fluid typically demonstrates a modest lymphocytic pleocytosis and increased protein; CSF glucose is most often normal. Autopsy studies demonstrate perivascular inflammatory infiltrates and occasionally intravascular thrombi in the brain, pathologic changes that could easily explain the seizures that sometime accompany RMSF. Focal CNS findings are relatively infrequent in patients with these infections, and survivors typically do not have prominent neurologic sequelae. Whether ehrlichia infections have significant neurologic involvement remains unclear—although headaches and alterations of consciousness are described frequently, only a few case reports have described focal brain abnormalities.
Arthropod-borne virus encephalitis
Published in Avindra Nath, Joseph R. Berger, Clinical Neurovirology, 2020
Colorado tick fever (CTF) is usually a self-limited febrile illness, but it can be complicated by neurological involvement [97]. Caused by a virus in the Coltivirus genus of the Reoviridae family, it is transmitted by Dermacentor andersoni ticks [98]. Often found in persons who work or have recreation in the Rocky Mountains [99], it has for years been confused with Rocky Mountain spotted fever. However, CTF is often distinguished by a biphasic, or saddlebacked, fever pattern and leukopenia. Rash, while occasionally found, is infrequent. The onset is abrupt with fever, headache and muscle aches. Duration of illness is seven to 10 days, punctuated often by a two to three day afebrile period midway in the course. Neurological complications include meningitis, meningoencephalitis, and encephalitis [97,98,100]. Virus isolation can be achieved from the blood throughout the febrile course. No treatment or preventative measure is currently available for CTF [101].
Prevalence of Spotted Fever Group Rickettsia in North-Eastern Poland
Published in Infectious Diseases, 2019
Karol Borawski, Justyna Dunaj, Piotr Czupryna, Sławomir Pancewicz, Renata Świerzbińska, Agnieszka Żebrowska, Anna Moniuszko-Malinowska
Rickettsia taxonomy includes four groups: Typhus group, Spotted Fever Group, Rickettsia bellii and Rickettsia canadensis groups. Rickettsia is small (0.3–0.5; 0.8–2.0 μm Gram-negative obligate intracellular bacilli. Spotted Fever Group rickettsiosis belongs to tick-borne diseases. In Poland three species are considered to be the etiological agents of Spotted Fever Group infections: Rickettsia slovaca, Rickettsia raoultii and Rickettsia helvetica. They are transmitted by Ixodes and Dermacentor ticks [5]. Ticks can be infected with Rickettsia spp. transovarially and transstadially [8,9]. The Spotted Fever Group Rickettsia commonly present with non-specific clinical signs and symptoms. Average incubation period is 3–12 d after a tick bite. Symptoms include fever, headache, muscle and articular pain, maculopapular or papulovesicular rash, in some cases – black eschar or ulcerative skin lesion in the bitten area. Lymph nodes enlargement is observed [10].
Spotted fever diagnosis: Experience from a South Indian center
Published in Pathogens and Global Health, 2021
Elangovan D, Perumalla S, Gunasekaran K, Rose W, Verghese V p, Abhilash K Pp, Prakash Jaj, Dumler Js
In a majority (≈90%), a macular or maculopapular rash appeared by the fifth day as reported in the literature [7,27]. Most of the cases of spotted fever occurred in cooler months as reported earlier [24]. The increase in spotted fever in cooler months is likely to be related to increased tick activity as described by Latha et al. in 2004 [28]. None of our cases had eschars; similar findings have been reported previously from India [8,9,11,16]. Our data suggest a strong association of rash on the palms and soles, in an individual with a febrile rash, with a diagnosis of spotted fever. These findings are similar to that reported earlier from our center [8,29] and by others [30–32].
Seropositivity to Midichloria mitochondrii (order Rickettsiales) as a marker to determine the exposure of humans to tick bite
Published in Pathogens and Global Health, 2019
Valentina Serra, Viktoria Krey, Christina Daschkin, Alessandra Cafiso, Davide Sassera, Horst-Günter Maxeiner, Letizia Modeo, Carsten Nicolaus, Claudio Bandi, Chiara Bazzocchi
Ixodes ricinus, the main vector of LB in Europe [5], presents a wide geographical distribution throughout the European continent [8–10]. Moreover, this tick is responsible for the transmission of over 90% of the TBDs occurring in this area [11], being also a competent vector of other pathogens, including spotted fever group Rickettsia species, Borrelia miyamotoi, Anaplasma phagocytophilum, Babesia divergens and Babesia microti. Human cases of parasitism by I. ricinus are rising, and many factors are involved in the current spread of this species [12,13] leading to a higher risk of tick bite exposure.