SFTSV infection in rodents and their ectoparasitic chiggers

Abstract

SFTSV, a tick-borne bunyavirus causing a severe hemorrhagic fever termed as severe fever with thrombocytopenia syndrome (SFTS). To evaluate the potential role of rodents and its ectoparasitic chiggers in the transmission of SFTSV, we collected wild rodents and chiggers on their bodies from a rural area in Qingdao City, Shandong Province, China in September 2020. PCR amplification of the M and L segments of SFTSV showed that 32.3% (10/31) of rodents and 0.2% (1/564) of chiggers (Leptotrombidium deliense) from the rodents were positive to SFTSV. Our results suggested that rodents and chiggers may play an important role in the transmission of SFTSV, although the efficiency of chiggers to transmit SFTSV needs to be further investigated experimentally.

Fig 1. Photograph of chiggers collected from small mammals.

(A) A Tscherskia triton infested by chiggers in the external ear canal (left) and a chigger photographed with digital microscope (right). (B) A chigger was fixed on the microscope slide (left, as indicated by the arrow) and photographed with an Olympus microscope (right).

Fig 2. Phylogenetic analysis based on the partial nucleotide sequences of SFTSV M and L segments.

(A) M segment (638bp). (B) L segment (327bp). The SFTSV sequences obtained in this study were marked by triangles (from rodents) and a circle (from chiggers). The phylogenetic trees were generated with Maximum Likelihood method by the MEGA 7.0 software (1,000 bootstrap replicates). Bootstrap value >75% was shown at nodes. The Guertu virus, belonging to the genus Phlebovirus of the family Phenuiviridae, was used as outgroup. Scale bars indicated substitutions per site. The reference sequences were named as: GenBank accession number-host-country.