Natural Transmission Model for Severe Fever With Thrombocytopenia Syndrome Bunyavirus in Villages of Hubei Province, China

Abstract

Severe fever with thrombocytopenia syndrome (SFTS), an emerging high-fatality infectious disease, is caused by a novel bunyavirus. However, a clear natural transmission model has not yet been established.We conducted a cross-sectional study with in-depth investigation of villages to systematically understand the transmission and risk factors among humans, host animals, and vectors. Village residents were interviewed using standardized questionnaires, in which there were confirmed cases of new infections, between August 2012 and May 2013. Serum samples from all villagers and animals, as well as tick specimens, were collected for qRT-PCR and antibody testing.The seropositivity rate among villagers was 8.4% (35/419), which was lower than that among domesticated animals (54.0%, 27/50; χ2 = 81.1, P < 0.05). SFTS viral RNA was most commonly detected among domesticated animals (14.0%), followed by ticks (3.1%) and humans (1.7%; χ2 = 23.1, P < 0.05). The homology of the S gene fragment was 98%. Tick bites were significantly associated with SFTSV infection (Conditional Logistic Regression odds ratio [OR] = 2.5, 95% confidence interval [CI], 1.0–6.6).We provided systematic evidence on a natural transmission model for SFTSV from reservoir hosts (domesticated animals) to vectors (Haemaphysalis longicornis) to humans, and close contact with SFTS confirmed patients was not found to be a risk factor for natural transmission.

Risk Factors for Bunyavirus-Associated Severe Fever with Thrombocytopenia Syndrome: A Community-Based Case-Control Study

“…However, all of the cases in the study were sporadic and not linked epidemiologically, so we did not analyze the variable of “contact with blood or mucous of an SFTS patient”. One study found that there was no statistically significant difference for seroprevalence of SFTSV antibodies between those who had been in close contact with an SFTS patient and those who had not [27], suggesting that person-to-person transmission is not the main risk factor for infection, and this mode of transmission is probably limited.…”

Epidemiological and Clinical Features of Severe Fever with Thrombocytopenia Syndrome During an Outbreak in South Korea, 2013–2015

“…Although human-to-human transmission has been reported in China and South Korea,7–9 SFTS is transmitted mainly by ticks; Ixodidae ticks, in particular, are implicated as vectors of SFTSV 1,10,11. A previous study in South Korea reported that the minimum infection rate of SFTSV in Haemaphysalis longicornis ticks, major vectors of SFTSV, was 0.46% 12.…”

Development of a reverse transcription polymerase chain reaction for the detection of severe fever with thrombocytopenia syndrome virus from suspected infected animals

“…Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral hemorrhagic fever that was first identified in China (1), with cases since reported in Japan, South Korea, Vietnam and Taiwan (2,3). SFTS virus (SFTSV) has been identified as a causative virus of SFTS belonging to the genus Banyangvirus, family Phenuiviridae, order Bunyavirales.…”

“…SFTS has been considered to be mainly transmitted by tick bites. Ticks infest a variety of animals, and viral RNA and antibodies against SFTSV have been detected in wild animals, domestic animals and companion animals, such as dogs and cats [1][2][3][4][5]. Since these animals show no clinical symptoms, they have been considered subclinically infected with SFTSV.…”