Serosurvey and laboratory diagnosis of imported sandfly fever virus, serotype Toscana, infection in Germany

Abstract

SUMMARYOf eight acute infections in German tourists caused by sandfly fever virus, serotype Toscana (TOS), and diagnosed clinically and serologically, seven were acquired during visits to Tuscany, Italy, and one to Coimbra, Portugal. An indirect immunofluorescence assay (IFA) using infected cells, and a newly developed enzyme-immunoassay (EIA) using crude virus antigen prepared from infected Vero-E6 cells was used to detect anti-TOS IgM and IgG. In a seroepidemiological survey of 859 health care workers and medical students, anti-TOS IgG was detected in 1-0% by IFA, and in 0 7 % by EIA. In 2034 German patients hospitalized for various diseases, 1 6 % were positive for anti-TOS IgG by IFA, and 0-8 % by EIA. Anti-TOS IgG was detected in 43 samples of commercial immunoglobulins at titres of 10-1000 by EIA. Although the seroprevalence of antibodies to TOS is low in Germany, TOS infection should be considered in patients returning from endemic areas who complain of fever, and headaches, and have symptoms of meningitis.

An outbreak of West Nile fever among migrants in Kisangani, Democratic Republic of Congo.

“…For the detection of IgM antibodies against dengue virus (types 1-4), West Nile virus, yellow fever virus, and Sindbis virus, an IgM capture ELISA was used as previously described. 6,16,17 IgM antibodies against Rift Valley fever virus, Chikungunya virus, Crimean Congo hemorrhagic fever virus, and R. typhi were measured by an indirect immunofluorescence assay as described. 18,19 Detection of IgG antibodies.…”

“…For the detection of IgG antibodies against dengue virus types 1-4 and West Nile virus, an indirect ELISA was used as previously described. 16,17 Binding of the IgG antibodies was detected using goat anti-human IgG antibodies labeled with horseradish peroxidase. IgG antibodies against Chikungunya virus, Crimean Congo hemorrhagic fever virus, Sindbis virus, yellow fever virus, Rift Valley fever virus, and R. typhi were measured by an indirect immunofluorescence assay as described.…”

Performance of Various Commercial Assays for the Detection of Toscana Virus Antibodies

“…IgM can still be detected at least 1 year after the exposure, whereas IgG levels slowly increase, reaching a peak in the convalescent phase and persists for several years (Magurano and Nicoletti 1999). Various methods can be used for the detection of TOSV IgM and/or IgG antibodies, including hemagglutination inhibition, indirect immunofluorescence test (IIFT), enzyme-linked immunosorbent assay (ELISA), immunoblot (IB), and virus neutralization test (VNT) (Clarke and Cassals 1958, Eitrem et al 1991b, Schwarz et al 1995, Magurano and Nicoletti 1999. Some of these assays are commercially available and have been developed with partially purified antigens, infected cells, or recombinant viral proteins (Eitrem et al 1991b, Schwarz et al 1995, Schwartz et al 1998, Ciufolini et al 1999).…”

Serological Survey of Toscana Virus Infections in a High-Risk Population in Italy

“…This neuropathogenic infection is more frequent during the summer, with a peak in August because of the life cycle of the insect vector and because of increased tourism in areas of endemicity (3,5,8; Schwarz, T. F., S. Glich, and G. Jäger, Letter, Lancet ii:803, 1993). The direct diagnostic procedures for the TOS virus infection are the isolation method and, more recently, the detection of viral RNA directly in the cerebrospinal fluid (3-5, 11-13; Calisher et al, letter; Schwarz et al, letter).…”

“…The detection of the specific antibodies is evaluated by serological techniques, such as indirect immunofluorescence assay, plaque reduction neutralization test, immunoblotting, and enzyme immunoassay (EIA). Recently, the EIA test has been performed using the recombinant viral nucleoprotein (rN) as antigen (5,6,9,10,12). We used this method to evaluate the circulation and the pathogenicity of TOS virus in the area of endemicity of central and southern Tuscany, including in this study a selected population of forestry workers occupationally exposed to the habitat of Phlebotomus spp.…”