Toscana Virus: Ten Years of Diagnostics in Portugal

Toscana virus (TOSV) is an emerging sandfly-borne virus within the Phlebovirus genus. Although most infections caused by this virus present as asymptomatic or with minimal symptomatology, TOSV may emerge as a febrile disease or sporadic cases of neurological disease such as meningitis or meningoencephalitis. This pathogen is distributed throughout the Mediterranean basin, along with the spatial distribution of its recognized sandfly vector, Phlebotomus perniciosus. Portugal, after Italy, was the second country considered endemic for this virus, with the first case of acquired infection published in 1985. Although little is known about the circulation of this virus in Portugal, the laboratory diagnosis of TOSV is available at the Centre for Vectors and Infectious Diseases Research of the National Institute of Health Dr. Ricardo Jorge (CEVDI/INSA), since 2007. The aim of this study is to report the results of the diagnosis of TOSV at the CEVDI/INSA, between 2009 and 2018. The diagnosis of TOSV in the CEVDI/INSA is included in the arboviruses and vector-borne neurotropic viruses panels or can be performed, when specified, for TOSV only. Direct detection is made in cerebrospinal fluid samples and is available for TOSV by specific real-time reverse transcription polymerase chain reaction followed by conventional real-time reverse transcription polymerase chain reaction for sequencing purposes, if positive. For indirect diagnosis, performed in serum samples, an in-house immunofluorescence assay for the detection of IgM and IgG antibodies against TOSV is used. A commercial immunofluorescence assay consisting in a mosaic of four phleboviruses is also available, in which, in addition to TOSV, antibody detection for sandfly fever Naples virus, sandfly fever Sicilian virus and sandfly fever Cyprus virus can be done. All diagnostic tests requested by clinicians to the CEVDI/INSA for arboviruses, neurotropic viruses and/or TOSV between January 2009 and December 2018, were included in this study. During the study period, the CEVDI/INSA received samples from 608 patients with diagnostic requests for TOSV. Five acute TOSV infections and one acute sandfly fever Sicilian virus infection were confirmed in serum samples. Three other patients had serological evidence of previous contact with the virus. Two of the six patients with acute infection developed febrile syndrome, and the other four presented with neurological disease: meningitis (n = 2), meningoencephalitis (n = 1)