First Indications of Omsk Haemorrhagic Fever Virus beyond Russia

Abstract

Omsk haemorrhagic fever virus (OHFV) is the agent leading to Omsk haemorrhagic fever (OHF), a viral disease currently only known in Western Siberia in Russia. The symptoms include fever, headache, nausea, muscle pain, cough and haemorrhages. The transmission cycle of OHFV is complex. Tick bites or contact with infected small mammals are the main source of infection. The Republic of Kazakhstan is adjacent to the endemic areas of OHFV in Russia and febrile diseases with haemorrhages occur throughout the country—often with unclear aetiology. In this study, we examined human cerebrospinal fluid samples of patients with suspected meningitis or meningoencephalitis with unknown origins for the presence of OHFV RNA. Further, reservoir hosts such as rodents and ticks from four Kazakhstan regions were screened for OHFV RNA to clarify if this virus could be the causative agent for many undiagnosed cases of febrile diseases in humans in Kazakhstan. Out of 130 cerebrospinal fluid samples, two patients (1.53%) originating from Almaty city were positive for OHFV RNA. Screening of tick samples revealed positive pools from different areas in the Akmola region. Of the caught rodents, 1.1% out of 621 were positive for OHFV at four trapping areas from the West Kazakhstan region. In this paper, we present a broad investigation of the spread of OHFV in Kazakhstan in human cerebrospinal fluid samples, rodents and ticks. Our study shows for the first time that OHFV can not only be found in the area of Western Siberia in Russia, but can also be detected up to 1.600 km away in the Almaty region in patients and natural foci.

Geographical distribution and pathogenesis of ticks and tick-borne viral diseases

“…OHFV is a type of flavivirus that causes hemorrhagic fever primarily in the western Siberian region, including Omsk, Novosibirsk, Kurgan, and Tyumen ( Růžek et al, 2010 ; Zhang et al, 2019 ). Ticks ( D. reticulatus , D. marginatus , and I. persulcatus ) transmit OHFV to humans and animals after feeding on infected hosts ( Wagner et al, 2022 ). The D. reticulatus has evolved several extraordinary characteristics; for example, it has a high reproduction rate, a rapid life cycle completion, can survive underwater for months, and has a diverse host range ( Földvári et al, 2016 ), which could enable OHFV transmission outside Russia ( Wagner et al, 2022 ).…”

“…Ticks ( D. reticulatus , D. marginatus , and I. persulcatus ) transmit OHFV to humans and animals after feeding on infected hosts ( Wagner et al, 2022 ). The D. reticulatus has evolved several extraordinary characteristics; for example, it has a high reproduction rate, a rapid life cycle completion, can survive underwater for months, and has a diverse host range ( Földvári et al, 2016 ), which could enable OHFV transmission outside Russia ( Wagner et al, 2022 ). In Russia, Dermacentor ticks serve as parasites that feed on small mammals, wild ungulates, domestic animals, and humans throughout their life cycle ( Růžek et al, 2010 ), as shown in Figure 1C .…”

“…According to evidence, ticks transmit OHFV to rodents (muskrats, narrow-skulled voles, and water voles) after feeding on an infected host. Moreover, OHFV has also been isolated from mosquitoes, Coquilletidia richiardii , Ochlerotatus excruciates , and yellow pygmy rice rat, Oligoryzomys flavescens ( Wagner et al, 2022 ). Findings also show that OHFV isolated from different ticks and hosts differs from the early isolated strains ( Růžek et al, 2010 ; Zhang et al, 2019 ).…”

“…It was speculated that the introduction of muskrats to Siberia might be responsible for the OHFV emergence, as the area was disease-free before ( Růžek et al, 2010 ). Russians and Kazakhstanis have reportedly been aware of OFHV’s chronic and fatal infections ( Ruzek et al, 2013 ; Wagner et al, 2022 ). Recently, Wagner and researchers reported OHFV incidence outside Russia (i.e., in the Republic of Kazakhstan) ( Wagner et al, 2022 ).…”

Ophthalmic consequences of viral hemorrhagic fevers: Insights from the clinic and laboratory

“…For example, only one study has been published regarding ocular manifestations in Omsk hemorrhagic fever, which noted subconjunctival hemorrhages in the early phases and scleral injection in the later phases (38). Since the second phase of illness includes meningo-encephalitis, it seems probable that this phase could manifest with posterior segment inflammation or hemorrhage (39,40). Similarly, Alkhurma hemorrhagic fever has been known to cause ocular symptoms including orbital pain, photophobia and conjunctival injection, but comprehensive ophthalmic exams in exposed patients would be useful to establish whether inflammatory changes are present within the eye and orbit, as photophobia and orbital pain usually indicate an inflammatory or uveitic process (41, 42).…”