Prevalence and homology analysis on human and animals severe fever with thrombocytopenia syndrome virus infection in Yantai of Shandong province / 中华流行病学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To learn the prevalence of infection of human and animals severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) in Yantai, Shandong province, and to analyze the pathogenic features of SFTSV as well as its relationship between human and animal hosts.</p><p><b>METHODS</b>From April to November in 2011, 3 576 serum samples were collected from domesticated animals, including sheep, cattle, pigs, dogs, chickens, in Laizhou and Penglai areas where fever with thrombocytopenia syndrome frequently occurred among local residents. Total SFTSV antibodies and virus-specific nucleic acids of the serum were tested by ELISA and Real time RT-PCR, respectively. SFTSV infection on each animal was observed in different months. 2 590 human serum samples were also collected in Laizhou and Penglai areas, with IgG antibodies tested by ELISA. Virus was isolated with Vero cells from the serum which SFTSV viral nucleic acids were positive. S fragments were amplified by RT-PCR and sequenced, with homology analysis conducted on these sequences.</p><p><b>RESULTS</b>The overall positive rate of serum samples from animals on the total SFTSV antibodies was 40.24% (1 439/3 576) while the positive rate for specific nucleic acids was 4.56% (163/3 576). The positive rates for SFTSV antibodies were 62.78%, 52.97%, 45.56%, 28.73%, 1.45% and the positive rates for specific nucleic acids were 5.72%, 4.63%, 3.02%, 5.25% and 3.73%, in sheep, cattle, chickens, dogs, pigs, respectively. The antigens/antibodies for SFTSV in animals changed seasonally. The overall positive rate for SFTSV IgG antibody from 2 590 human samples was 5.41%. Thirteen virus strains were isolated from these serum samples (10 strains from human and 3 strains from animals). The nucleotide homology of 13S fragments' sequences ranged from 95.23% to 100.00% and the nucleotide homology with the isolates from other provinces were between 94.72% and 99.13%. The homology was considered to be high.</p><p><b>CONCLUSION</b>High prevalence of SFTSV infections occurred both in human and domestic animals in Yantai city. The nucleotide sequences of SFTSV were highly homologous among human and domestic animals. The findings suggested that domesticated animals might serve as SFTSV proliferation and the hosts for transmission thus should be attached great importance.</p>