West Nile virus infections in Hungary: Epidemiological update and phylogenetic analysis of the Hungarian virus strains between 2015 and 2022.

Following the introduction of the West Nile virus (WNV) into Hungary in 2004, it has shortly become one of the most important human arbovirus infections, with a gradually increasing number of cases. The study aimed to summarize the current epidemiological situation in Hungary and sequence the WNV PCR-positive clinical specimens and virus isolates by next-generation whole genome sequencing (NGS) to obtain a detailed phylogenetic analysis of the circulating virus strains. Whole blood and urine samples from confirmed WNV-infected patients and WNV isolates were investigated by reverse transcription PCR assays. Genome sequencing was carried out by Sanger-method, followed by NGS on the Illumina MiSeq platform. Altogether 499 human infections were diagnosed between 2004 and 2022. A particularly remarkable increase in human WNV infections was observed in 2018, while the number of reported cases significantly decreased during the COVID-19 pandemic. Between 2015 and 2022, 15 WNV isolates, and 10 PCR-positive clinical specimens were investigated by NGS. Phylogenetic analysis revealed that the major European WNV lineage 2 clades, namely the Eastern European (or Russian) and the Central European (or Hungarian) clades, are presented in Hungary. Strains of the Balkan and other European clusters within the Central European clade are co-circulating in the country, following a characteristic geographical distribution. In Hungary, the presence and co-circulation of multiple lineage 2 WNV strains could be identified in the last few years. Therefore, in light of the 2018 WNV outbreak, sequence-based typing of the currently circulating strains could highly support outbreak investigations.

West Nile and Usutu virus seroprevalence in Hungary: A nationwide serosurvey among blood donors in 2019.

In Hungary, West Nile virus (WNV) has been responsible for 459 laboratory confirmed human cases between 2004 and 2019, while the first human Usutu virus (USUV) infection was confirmed only in 2018. A comprehensive serosurvey was conducted among blood donors to assess the WNV and USUV seroprevalence in 2019, one year after the largest European WNV epidemic. Altogether, 3005 plasma samples were collected and screened for WNV and USUV specific Immunoglobulin G (IgG) antibodies by Enzyme-Linked Immunosorbent Assay (ELISA). All reactive samples were further tested for tick-borne encephalitis virus IgG antibodies by ELISA. Indirect immunofluorescence test and microneutralization assay were used as confirmatory methods. Overall, the WNV seroprevalence was 4.32%, and in five blood donors USUV seropositivity was confirmed. The highest seroprevalence was measured in Central, Eastern and Southern Hungary, while the Western part of the country proved to be less affected. There was a statistically strong association between the WNV seroprevalence of 2019 and the cumulative incidence in the period of 2004 and 2019 calculated for every NUTS 3 region. The last WNV serological screening was performed in 2016 and the prevalence of anti-WNV IgG proved to be 2.19%. One year after the 2018 WNV outbreak, a significant increase in seroprevalence was observed in the Hungarian population and evidence for USUV seropositivity was also obtained. The spatial pattern of seroprevalence can support the identification of high-risk areas raising awareness of the need for increased surveillance, such as screening vector, equine, and avian populations. The communication with general practitioners and other professionals in primary health care services can support the early identification of acute human cases. Education and awareness-raising on the importance of protection against mosquito vectors amongst residents are also important parts of preventive measures.

Detection of the first appearance of SARS-CoV-2 virus in Hungary based on retrospective testing of respiratory samples / A SARS-CoV-2 vírus magyarországi megjelenésének kimutatása légúti minták retrospektív vizsgálata alapján.

INTRODUCTION: In Hungary, SARS-CoV-2 was first detected in the swab samples of two Iranian patients on March 4, 2020. After finding the first positive cases, the question arose whether the virus had entered Hungary and caused infections before this date. Before March 4, 2020, except for the two above-mentioned samples, none of the 224 swab samples received specifically for SARS-CoV-2 tested positive. AIM: The National Reference Laboratory for Respiratory Viruses of the National Public Health Center aimed to carry out a retrospective study of the swab and other samples taken for testing respiratory virus infections between January 1, and April 19, 2020 sent by sentinel physicians within the influenza surveillance for diagnostic purposes. METHOD: For the study, we used swab samples taken weekly by sentinel physicians of the influenza surveillance service, and other samples received for diagnostic purposes. Tests were performed using real-time PCR. RESULTS: All the 465 swab samples sent by sentinel physicians were found to be SARS-CoV-2 negative. Also, of the 551 samples collected for diagnostic reasons of other respiratory viruses, no SARS-CoV-2 positive was found among those taken before March 4. CONCLUSION: Based on our data, it is very likely that prior to the first cases diagnosed on March 4, 2020, SARS-CoV-2 did not cause clinically symptomatic infections in Hungary. Orv Hetil. 2020; 161(38): 1619-1622.