[Source: Eurosurveillance, full page: (LINK). Abstract, edited.]
Extraordinary increase in West Nile virus cases and first confirmed human Usutu virus infection in Hungary, 2018
Anna Nagy1,2, Eszter Mezei2,3, Orsolya Nagy1,4, Tamás Bakonyi5,6, Nikolett Csonka1, Magdolna Kaposi1, Anita Koroknai1, Katalin Szomor7, Zita Rigó7, Zsuzsanna Molnár3, Ágnes Dánielisz3, Mária Takács1,4
Affiliations: 1 National Reference Laboratory for Viral Zoonoses; National Public Health Center, Budapest, Hungary; 2 These authors contributed equally to this work; 3 Department of Communicable Diseases Epidemiology and Infection Control; National Public Health Center, Budapest, Hungary; 4 Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary; 5 Department of Microbiology and Infectious Diseases, University of Veterinary Medicine, Budapest, Hungary; 6 Viral Zoonoses, Emerging and Vector-borne Infections Group, Institute of Virology, University of Veterinary Medicine, Vienna, Austria; 7 National Reference Laboratory for Viral Exanthematous Diseases; National Public Health Center, Budapest, Hungary
Correspondence: Anna Nagynagy.annannk.gov.hu
Citation style for this article: Nagy Anna, Mezei Eszter, Nagy Orsolya, Bakonyi Tamás, Csonka Nikolett, Kaposi Magdolna, Koroknai Anita, Szomor Katalin, Rigó Zita, Molnár Zsuzsanna, Dánielisz Ágnes, Takács Mária. Extraordinary increase in West Nile virus cases and first confirmed human Usutu virus infection in Hungary, 2018. Euro Surveill. 2019;24(28):pii=1900038. https://doi.org/10.2807/1560-7917.ES.2019.24.28.1900038
Received: 07 Jan 2019; Accepted: 02 Apr 2019
During the 2018 WNV transmission season, similarly to other endemic areas in Europe, a large number of human West Nile virus (WNV) infections were reported in Hungary.
We summarise the epidemiological and laboratory findings of the 2018 transmission season and expand experiences in flavivirus differential diagnostics.
Every patient with clinical suspicion of acute WNV infection was in parallel tested for WNV, tick-borne encephalitis virus and Usutu virus (USUV) by serological methods. Sera, whole blood and urine samples were also tested for the presence of viral nucleic acid.
Until the end of December 2018, 215 locally acquired and 10 imported human WNV infections were notified in Hungary. All reported cases were symptomatic; most of them exhibited neurological symptoms. In a large proportion of tested individuals, whole blood was the most appropriate sample type for viral nucleic acid detection, but because whole blood samples were not always available, testing of urine samples also extended diagnostic possibilities. In addition, the first human USUV infection was confirmed in 2018 in a patient with aseptic meningitis. Serological cross-reactions with WNV in different serological assays were experienced, but subsequent molecular biological testing and sequence analysis identified Europe lineage 2 USUV infection.
Careful interpretation and simultaneous application of different laboratory methods are necessary to avoid misdiagnosis of human USUV cases. Expansion of the laboratory-confirmed case definition criteria for detection of viral RNA in any clinical specimens to include urine samples could increase diagnostic sensitivity.
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Keywords: WNV; Usutu virus; Hungary.