Investigations on California Serogroup Orthobunyaviruses in the Tyrols: First Description of Tahyna Virus in The Alps

Abstract

Seroprevalence rates for immunoglobulin G (IgG) antibodies to Tahyna virus (TAHV) and Inkoo virus (INKV) were determined in sera of 1630 blood donors from North, East, and South Tyrol by immunofluorescence assays (IFAs) and confirmatory serum neutralization tests (SNTs). Ten sera (0.6%) reacted positive by TAHV IFA, five of which (0.3%) were confirmed by SNT. Eleven sera (0.7%) reacted positive in the INKV IFA; only one thereof (0.06%) was verified by subsequent SNT. To identify the source of infections, mosquitoes were trapped at 18 sampling sites in the study area, resulting in the collection of 2571 adult mosquitoes: 1254 individuals of the genus Aedes (48.8% of total) including A. albopictus, 640 Culex (24.9%), 303 Coquillettidia (11.8%), 252 Ochlerotatus (9.8%), 49 Anopheles (1.9%), and 73 mosquitoes of the genus Culiseta (2.8%). The mosquitoes were pooled according to species, trapping site, and time, and were tested by RT-PCR for the presence of California serogroup orthobunyavirus nucleic acids. PCR amplification products were obtained in five of 195 pools (2.6%), and all were identified as TAHVs by subsequent sequencing. This represents the first evidence of TAHV circulation and human exposure in the Tyrols and in the alpine region in general. Interestingly, all TAHV sequences were identified in Culex pipiens/torrentium mosquitoes. Whether other California serogroup orthobunyaviruses such as INKV are also circulating in this area is subject of further investigations on larger numbers of mosquitoes.

Mosquito-borne diseases in Europe: an emerging public health threat

“…An example is the TAHV that was detected or isolated from different sources in the 70s in European countries (Figure 1) but was also recently directly detected in mosquitoes in Italy 59 and Austria. 60 These results are consistent with the continuous circulation of the arboviruses within the European territory, which could result in several undiagnosed human cases of mild or sporadic disease. The possible recrudescence of these viruses may be due to the significant warming recorded in recent decades in Europe, which could change the distribution and abundance of mosquitoes or increase virus replication in mosquito vectors.…”

Mosquitoes (Diptera: Culicidae) and their relevance as disease vectors in the city of Vienna, Austria

“…The outbreak in 2003 was facilitated by an extraordinary hot summer, and it is likely that similar climatic conditions could initiate further USUV outbreaks (Brugger and Rubel 2009 ). Recently, Sonnleitner et al ( 2014 ) isolated Tahyna virus (TAHV) from Cx. pipiens complex pools collected in the Alps (Province of Tyrol, western Austria).…”

Lesser-known bunyavirus infections

“…More recently, a new member of this serological group was isolated in Finland; the five new isolates have been described as Mohko isolates of the Chatanga virus (7). The related Tahyna virus has been found in Asia, Africa and Europe (12,13,65). INGV has been isolated from birds, pigs and Culex species mosquitoes from Thailand, Indonesia, India and Africa (27,28,29).…”

“…The California group of viruses has been associated primarily with encephalitis in humans and has been extensively studied and reviewed (1). TAHV has been associated with fever, headache, nausea, malaise and pharyngitis in humans (12,13). Of the Bunyamwera group, CVV is primarily pathogenic for young domestic ruminants, with subclinical disease being most common in adult animals (14,33).…”