Seroprevalence and Risk Factors of Inkoo Virus in Northern Sweden

Abstract

The mosquito-borne Inkoo virus (INKV) is a member of the California serogroup in the family Bunyaviridae, genus Orthobunyavirus. These viruses are associated with fever and encephalitis, although INKV infections are not usually reported and the incidence is largely unknown. The aim of the study was to determine the prevalence of anti-INKV antibodies and associated risk factors in humans living in northern Sweden. Seroprevalence was investigated using the World Health Organization Monitoring of Trends and Determinants in Cardiovascular Disease study, where a randomly selected population aged between 25 and 74 years (N = 1,607) was invited to participate. The presence of anti-INKV IgG antibodies was determined by immunofluorescence assay. Seropositivity for anti-INKV was significantly higher in men (46.9%) than in women (34.8%; P < 0.001). In women, but not in men, the prevalence increased somewhat with age (P = 0.06). The peak in seropositivity was 45–54 years for men and 55–64 years for women. Living in rural areas was associated with a higher seroprevalence. In conclusion, the prevalence of anti-INKV antibodies was high in northern Sweden and was associated with male sex, older age, and rural living. The age distribution indicates exposure to INKV at a relatively early age. These findings will be important for future epidemiological and clinical investigations of this relatively unknown mosquito-borne virus.

Acute Human Inkoo and Chatanga Virus Infections, Finland

“…Results from the diagnostic test in use show cross-reactions between the serogroup viruses. Most (82%) of the acute infections in this study were INKV cases, confirmed by using PRNT, which showed >4-fold titer differences, consistent with findings that INKV is the major California serogroup agent in seroprevalence studies in Finland and Sweden ( 33 ). Although most cases seem subclinical or mild, the data in our study indicate that the clinical disease may occasionally be severe; all children with acute illness had INKV infection and were hospitalized.…”

Exploration of the main types of biome-scale culicid entomofauna (Diptera: Culicidae) in Europe and its relationship to the occurrence of mosquito-borne arboviruses

“…For example, Oc. hexodontus (Evander et al 2016) occur only in the boreal areas. The distributions of the mammalian hosts (e.g.…”

Risk factors associated with seropositivity to California serogroup viruses in humans and pet dogs, Quebec, Canada

“…JCV is thought to be amplified in a transmission cycle involving wild ungulates such as white-tailed deer and a variety of mosquito species, while for SHV the reservoir hosts are small mammals such as hares, squirrels and chipmunks [9][10][11][12][13]. High seroprevalence rates have been reported for both viruses in different wild mammal species from North America [14][15][16][17][18][19][20], suggesting that natural transmission cycles can be highly effective in maintaining CSGV activity. However, there has been little effort to assess which types of environment present a high risk of exposure to these viruses.…”