Clinical and laboratory characteristics of tick-borne rickettsiosis related to Rickettsia sibirica and Candidatus Rickettsia tarasevichiae

• Published in: Russian Journal of Infection and Immunity
• Main Authors: N. V. Rudakov, I. E. Samoylenko, S. V. Shtrek, S. A. Rudakova, L. V. Kumpan, Ya. P. Igolkina, V. A. Rar, E. V. Zhirakovskaya, S. E. Tkachev, N. V. Tikunova, T. V. Kostrykina, I. A. Blokhina, P. A. Lents
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Sankt-Peterburg : NIIÈM imeni Pastera 2022
• Subjects: candidatus rickettsia tarasevichiae; rickettsia sibirica; etiological agents; rickettsioses; clinical manifestations; ixodid ticks; Infectious and parasitic diseases; RC109-216; Krasnoyarsk Krai; Siberia
• Online Access: https://doi.org/10.15789/2220-7619-CAL-1597; https://doaj.org/article/80b483822ff548a18ff76326598b4de8

The Siberian tick-borne typhus (STT) is the most common tick-borne rickettsiosis (TBR) in Russia, registered in 17 administrative territories of the Southern Siberia and the Far East. The aim of this study was to describe clinical picture, pathological data and results of laboratory diagnostics during fatal mixed infection caused by two Rickettsia species most common in Russia — pathogenic Rickettsia sibirica and poorly examined Candidatus R. tarasevichiae, including identification of its etiological agents. A four-year-old girl in Krasnoyarsk Krai in a hyperendemic focus of the Siberian tick-borne typhus after tick sucking revealed typical TBR symptoms (scab at the site of tick suction, fever, spotted rash, myalgia) and meningeal syndrome, which is not typical for the Siberian tick-borne typhus. The child died on the seventh day of illness. Autopsy data (hepatosplenomegaly; cerebral edema, which was the immediate cause of death) and the results of histological examination (productive vasculitis of the brain, spinal cord and skin, polymorphic cell perivascular infiltrates in the liver and lungs, serous meningitis, myeloid hyperplasia of the spleen and lymph nodes, interstitial lymphoid infiltration in the myocardium) confirmed the clinical diagnosis of tick-borne rickettsiosis. The patient’s blood and brain samples were tested for a wide range of tick-borne pathogens and enteric viruses that cause brain damage using PCR followed by sequencing of the positive samples. The DNA of Rickettsia sibirica and Candidatus Rickettsia tarasevichiae was found in both blood and brain samples. R. sibirica was identified by the nucleotide sequences of gene fragments gltA, ompA and ompB, and Candidatus R. tarasevichiae — by the gltA and ompB genes using nested PCR and sequencing. All amplified fragments were sequenced in both directions; the obtained sequences were deposited in the GenBank database under the inventory numbers MK048467–MK048475. We have not identified other tick-borne pathogens or intestinal viruses in the ...