California encephalitis orthobunyaviruses in northern Europe

Inkoo virus (INKV) is a mosquito-borne virus belonging to the California serogroup (genus Orthobunyavirus, family Bunyaviridae) which includes many important human pathogens described especially in the USA. The association of INKV infection with clinical disease has not been confirmed, but occasional cases of meningitis and encephalitis have been diagnosed. However, the true incidence of acute infections is not known because ongoing research and laboratory diagnostics of INKV infections have been neglected for decades in the countries where the virus circulates. We established a serological test (IFA) to detect INKV antibodies, and studied protein-specific antibody responses. Antibody prevalence in humans in Finland and Sweden showed that 40-50% of the population had been infected with INKV or a related California serogroup virus. The seroprevalence was higher in older age groups, and in Finland, the prevalence increased northwards. We found that acute-phase sera had a distinct granular fluorescence pattern in IgG IFA, whereas those with pre-existing immunity showed a diffuse pattern. Using recombinant INKV proteins as antigens, the antibody response was showed predominantly to be against the N protein in early infection and also towards the Gc protein in the later stages of infection. We discovered a new California encephalitis virus isolate of the genus Orthobunyavirus in Finland from mosquitoes collected in 2007 and 2008 from the Ilomantsi and Sotkamo municipalities in Eastern Finland. The new isolates were named the Möhkö isolates of Chatanga virus (CHATV) since the genetic and serological findings suggested that the new virus isolates were most closely related to clusters of Russian orthobunyavirus CHATV isolates (99% N protein identity). Using samples from patients with febrile illness or neurological symptoms collected in the summertime between 2001 and 2013, we studied the frequency of acute INKV infections and the clinical picture of the patients. We found the frequency to be under 1%, but interestingly, not only INKV but also CHATV were confirmed to cause human infections. Most patients were not hospitalized, and they had visited a doctor most often once. The patients suffered from fever, headache, vomiting, disorientation, and seizures. INKV infections were more severe in children under 16 years, and CHATV infections were more severe in adults. In conclusion, we found a new mosquito-borne virus from Finland and showed for the first time that this virus was associated with a clinical disease. In addition, we described the clinical picture of INKV infection and showed that the infection is more severe in children if neurologic symptoms appear. These viruses are common in Finland, and their association with clinical disease in the summertime should not be forgotten.Hyttysvälitteinen Inkoo virus kuuluu Kalifornian enkefaliittiryhmään (Orthobunyavirus-suku, Bunyaviridae-heimo), joka sisältää monia tärkeitä patogeenejä etenkin Yhdysvalloissa. Inkoo virusinfektion yhteyttä kliiniseen tautiin ei ole vahvistettu, mutta satunnaisia aivokalvontulehdus- ja aivotulehdustapauksia on osoitettu. Todellista taudin esiintyvyyttä ja yleisyyttä ei tiedetä, koska Inkoo viruksen tutkimus ja laboratorio diagnostiikka on laiminlyöty vuosikymmeniä maissa, jossa virusta esiintyy. Tässä tutkimuksessa pystytettiin serologinen testi Inkoo virus vasta-aineiden osoittamiseksi ja tutkittiin vasta-aineiden yleisyyttä ihmisillä sekä proteiinivastetta Inkoo virusinfektiossa. Vasta-aineiden yleisyyttä tutkittiin Suomessa ja Ruotsissa ja todettiin että 40-50 % väestöstä oli kohdannut Inkoo viruksen tai toisen Kalifornian enkefaliittiryhmän viruksen. Seropositiivisuus oli korkeampi vanhemmissa ikäryhmissä, ja Suomessa se kasvoi pohjoiseen mentäessä. Osoitimme että vasta-ainevaste on infektio alkuvaiheessa pääasiassa N proteiinia vastaan, ja infektion edetessä vaste tulee myös Gc-proteiinia vastaan. Tutkimuksessa löysimme Suomesta uuden Kalifornian enkefaliittiryhmän viruksen hyttysistä, jotka oli kerätty vuosina 2007 ja 2008 Ilomantsin ja Sotkamon kunnista Itä-Suomesta. Uusi virus nimettiin Chatanga viruksen Möhkö kannaksi fylogeneettisten ja serologisten tulosten perusteella. Uusi viruskanta oli läheisintä sukua Venäjältä eristetylle orthobunyavirus-suvun Chatanga virukselle (N proteiini identiteetti 99 %). Akuutin Inkoo virusinfektion yleisyyttä ja potilaiden taudinkuvaa tutkittiin potilasnäytteistä, joita oli kerätty kesäisin 2001-2013. Potilailla oli todettu kuumetauti tai neurologisia oireita, mutta taudinaiheuttaja oli jäänyt epäselväksi. Löysimme Inkoo viruksen IgM-vasta-aineita alle 1 %, mutta Inkoo viruksen lisäksi osoitimme ensimmäistä kertaa, että myös Chatanga virus aiheuttaa infektioita ihmisessä. Potilaiden oireisiin kuului kuume, päänsärky, oksentelu ja sekavuus sekä potilailla havaittiin kouristuksia. Inkoo virusinfektiot olivat vakavampia alle 16-vuotiailla lapsilla, kun taas Chatanga virusinfektiot aikuisilla. Tässä tutkimuksessa löydettiin uusi hyttysvälitteinen virus (Chatanga virus) Suomesta ja osoitti ensimmäisen kerran, että tämä virus aiheuttaa tautia ihmisellä. Lisäksi kuvattiin Inkoo virusinfektion taudinkuvaa ja osoitettiin, että infektio on vakavampi lapsilla, jos neurologisia oireita esiintyy. Nämä virukset ovat yleisiä Suomessa ja niiden merkitystä kesäaikaisten infektioiden aiheuttajina ei pitäisi unohtaa

Seroprevalence and Risk Factors of Inkoo Virus in Northern Sweden

The mosquito-borne Inkoo virus (INKV) is a member of the California serogroup in the family Bunyaviridae, genus Orthobunyavirus. These viruses are associated with fever and encephalitis, although INKV infections are not usually reported and the incidence is largely unknown. The aim of the study was to determine the prevalence of anti-INKV antibodies and associated risk factors in humans living in northern Sweden. Seroprevalence was investigated using the World Health Organization Monitoring of Trends and Determinants in Cardiovascular Disease study, where a randomly selected population aged between 25 and 74 years (N = 1,607) was invited to participate. The presence of anti-INKV IgG antibodies was determined by immunofluorescence assay. Seropositivity for anti-INKV was significantly higher in men (46.9%) than in women (34.8%; P <0.001). In women, but not in men, the prevalence increased somewhat with age (P = 0.06). The peak in seropositivity was 45-54 years for men and 55-64 years for women. Living in rural areas was associated with a higher seroprevalence. In conclusion, the prevalence of anti-INKV antibodies was high in northern Sweden and was associated with male sex, older age, and rural living. The age distribution indicates exposure to INKV at a relatively early age. These findings will be important for future epidemiological and clinical investigations of this relatively unknown mosquito-borne virus.Peer reviewe

Lymphocytic choriomeningitis, Ljungan and orthopoxvirus seroconversions in patients hospitalized due to acute Puumala hantavirus infection

Background: The emergence and re-emergence of zoonotic and vector-borne diseases are increasing in Europe. Prominent rodent-borne zoonotic viruses include Puumala hantavirus (PUUV; the causative agent of nephropathia epidemica, NE), lymphocytic choriomeningitis virus (LCMV), and orthopoxviruses (OPV). In addition, Ljungan virus (LV) is considered a potentially zoonotic virus. Objective: The aim of this study was to compare clinical picture between acute PUUV patients with and without additional rodent-borne viral infections, to investigate if concurrent infections influence disease severity. Study design: We evaluated seroprevalence of and seroconversions to LCMV, LV and OPV in 116 patients hospitalized for NE. Clinical and laboratory variables were closely monitored during hospital care. Results: A total of five LCMV, 15 LV, and one OPV seroconversions occurred. NE patients with LCMV seroconversions were younger, and had lower plasma creatinine concentrations and platelet counts than patients without LCMV seroconversions. No differences occurred in clinical or laboratory findings between patients with and without seroconversions to LV and OPV. We report, for the first time, LCMV seroprevalence in Finland, with 8.5% of NE patients seropositive for this virus. Seroprevalences for LV and OPV were 47.8% and 32.4%, respectively. Conclusion: Cases with LCMV seroconversions were statistically younger, had milder acute kidney injury and more severe thrombocytopenia than patients without LCMV. However, the low number of seroconversion cases precludes firm conclusions. Concurrent LV or OPV infections do not appear to influence clinical picture for NE patients. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe

Infection with Possible Novel Parapoxvirus in Horse, Finland, 2013

A horse in Finland exhibited generalized granulomatous inflammation and severe proliferative dermatitis. After euthanization, we detected poxvirus DNA from a skin lesion sample. The virus sequence grouped with parapoxviruses, closely resembling a novel poxvirus detected in humans in the United States after horse contact. Our findings indicate horses may be a reservoir for zoonotic parapoxvirus.Peer reviewe

Acute Human Inkoo and Chatanga Virus Infections, Finland

Inkoo virus (INKV) and Chatanga virus (CHATV), which are circulating in Finland, are mosquitoborne California serogroup orthobunyaviruses that have a high seroprevalence among humans. Worldwide, INKV infection has been poorly described, and CHATV infection has been unknown. Using serum samples collected in Finland from 7,961 patients suspected of having viral neurologic disease or Puumala virus infection during the summers of 2001-2013, we analyzed the samples to detect California serogroup infections. IgM seropositivity revealed 17 acute infections, and cross neutralization tests confirmed presence of INKV or CHATV infections. All children (Peer reviewe

Infection with possible novel parapoxvirus in horse, Finland, 2013

A horse in Finland exhibited generalized granulomatous inflammation and severe proliferative dermatitis. After euthanization, we detected poxvirus DNA from a skin lesion sample. The virus sequence grouped with parapoxviruses, closely resembling a novel poxvirus detected in humans in the United States after horse contact. Our findings indicate horses may be a reservoir for zoonotic parapoxvirus.</p

Detection of group A streptococcus in children with confirmed viral pharyngitis and antiviral host response

Our aim was to study the detection of group A streptococcus (GAS) with different diagnostic methods in paediatric pharyngitis patients with and without a confirmed viral infection. In this prospective observational study, throat swabs and blood samples were collected from children (age 1-16 years) presenting to the emergency department with febrile pharyngitis. A confirmed viral infection was defined as a positive virus diagnostic test (nucleic acid amplification test [NAAT] and/or serology) together with an antiviral immune response of the host demonstrated by elevated (>= 175 mu g/L) myxovirus resistance protein A (MxA) blood concentration. Testing for GAS was performed by a throat culture, by 2 rapid antigen detection tests (StrepTop and mariPOC) and by 2 NAATs (Simplexa and Illumigene). Altogether, 83 children were recruited of whom 48 had samples available for GAS testing. Confirmed viral infection was diagnosed in 30/48 (63%) children with febrile pharyngitis. Enteroviruses 11/30 (37%), adenoviruses 9/30 (30%) and rhinoviruses 9/30 (30%) were the most common viruses detected. GAS was detected by throat culture in 5/30 (17%) with and in 6/18 (33%) patients without a confirmed viral infection. Respectively, GAS was detected in 4/30 (13%) and 6/18 (33%) by StrepTop, 13/30 (43%) and 10/18 (56%) by mariPOC, 6/30 (20%) and 9/18 (50%) by Simplexa, and 5/30 (17%) and 6/18 (30%) patients by Illumigene.Conclusion: GAS was frequently detected also in paediatric pharyngitis patients with a confirmed viral infection. The presence of antiviral host response and increased GAS detection by sensitive methods suggest incidental throat carriage of GAS in viral pharyngitis.</p

Novel flaviviruses from mosquitoes : Mosquito-specific evolutionary lineages within the phylogenetic group of mosquito-borne flaviviruses

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Inkoo and Sindbis viruses in blood sucking insects, and a serological study for Inkoo virus in semi-domesticated Eurasian tundra reindeer in Norway

Background Mosquito-borne viruses pose a serious threat to humans worldwide. There has been an upsurge in the number of mosquito-borne viruses in Europe, mostly belonging to the families Togaviridae, genus Alphavirus (Sindbis, Chikungunya), Flaviviridae (West Nile, Usutu, Dengue), and Peribunyaviridae, genus Orthobunyavirus, California serogroup (Inkoo, Batai, Tahyna). The principal focus of this study was Inkoo (INKV) and Sindbis (SINV) virus circulating in Norway, Sweden, Finland, and some parts of Russia. These viruses are associated with morbidity in humans. However, there is a knowledge gap regarding reservoirs and transmission. Therefore, we aimed to determine the prevalence of INKV and SINV in blood sucking insects and seroprevalence for INKV in semi-domesticated Eurasian tundra reindeer (Rangifer tarandus tarandus) in Norway. Materials and methods In total, 213 pools containing about 25 blood sucking insects (BSI) each and 480 reindeer sera were collected in eight Norwegian reindeer summer pasture districts during 2013-2015. The pools were analysed by RT-PCR to detect INKV and by RT-real-time PCR for SINV. Reindeer sera were analysed for INKV-specific IgG by an Indirect Immunofluorescence Assay (n = 480, IIFA) and a Plaque Reduction Neutralization Test (n = 60, PRNT). Results Aedes spp. were the most dominant species among the collected BSI. Two of the pools were positive for INKV-RNA by RT-PCR and were confirmed by pyrosequencing. The overall estimated pool prevalence (EPP) of INKV in Norway was 0.04%. None of the analysed pools were positive for SINV. Overall IgG seroprevalence in reindeer was 62% positive for INKV by IIFA. Of the 60 reindeer sera- analysed by PRNT for INKV, 80% were confirmed positive, and there was no cross-reactivity with the closely related Tahyna virus (TAHV) and Snowshoe hare virus (SSHV). Conclusion The occurrence and prevalence of INKV in BSI and the high seroprevalence against the virus among semi-domesticated reindeer in Norway indicate that further studies are required for monitoring this virus. SINV was not detected in the BSI in this study, however, human cases of SINV infection are yearly reported from other regions such as Rjukan in south-central Norway. It is therefore essential to monitor both viruses in the human population. Our findings are important to raise awareness regarding the geographical distribution of these mosquito-borne viruses in Northern Europe.Peer reviewe

Inkoo and Sindbis viruses in blood sucking insects, and a serological study for Inkoo virus in semi-domesticated Eurasian tundra reindeer in Norway

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.Background: Mosquito-borne viruses pose a serious threat to humans worldwide. There has been an upsurge in the number of mosquito-borne viruses in Europe, mostly belonging to the families Togaviridae, genus Alphavirus (Sindbis, Chikungunya), Flaviviridae (West Nile, Usutu, Dengue), and Peribunyaviridae, genus Orthobunyavirus, California serogroup (Inkoo, Batai, Tahyna). The principal focus of this study was Inkoo (INKV) and Sindbis (SINV) virus circulating in Norway, Sweden, Finland, and some parts of Russia. These viruses are associated with morbidity in humans. However, there is a knowledge gap regarding reservoirs and transmission. Therefore, we aimed to determine the prevalence of INKV and SINV in blood sucking insects and seroprevalence for INKV in semi-domesticated Eurasian tundra reindeer (Rangifer tarandus tarandus) in Norway. Materials and methods: In total, 213 pools containing about 25 blood sucking insects (BSI) each and 480 reindeer sera were collected in eight Norwegian reindeer summer pasture districts during 2013–2015. The pools were analysed by RT-PCR to detect INKV and by RT-real-time PCR for SINV. Reindeer sera were analysed for INKV-specifc IgG by an Indirect Immunofuorescence Assay (n=480, IIFA) and a Plaque Reduction Neutralization Test (n=60, PRNT). Results: Aedes spp. were the most dominant species among the collected BSI. Two of the pools were positive for INKV-RNA by RT-PCR and were confrmed by pyrosequencing. The overall estimated pool prevalence (EPP) of INKV in Norway was 0.04%. None of the analysed pools were positive for SINV. Overall IgG seroprevalence in reindeer was 62% positive for INKV by IIFA. Of the 60 reindeer sera- analysed by PRNT for INKV, 80% were confrmed positive, and there was no cross-reactivity with the closely related Tahyna virus (TAHV) and Snowshoe hare virus (SSHV). Conclusion: The occurrence and prevalence of INKV in BSI and the high seroprevalence against the virus among semi-domesticated reindeer in Norway indicate that further studies are required for monitoring this virus. SINV was not detected in the BSI in this study, however, human cases of SINV infection are yearly reported from other regions such as Rjukan in south-central Norway. It is therefore essential to monitor both viruses in the human population. Our findings are important to raise awareness regarding the geographical distribution of these mosquito-borne viruses in Northern Europe.publishedVersio