New virus linked to recently identified SFTS disease
MedWire News: Researchers may have pinpointed the cause of a recently identified acute febrile illness that emerged in rural China 2 years ago.
Severe fever with thrombocytopenia syndrome (SFTS), which had an initial case fatality rate of approximately 30%, is characterized by fever, gastrointestinal symptoms, thrombocytopenia, and leukocytopenia.
Now, senior researcher De-Xin Li (Chinese Center for Disease Control and Prevention, Beijing) and colleagues have linked the disease to a novel phlebovirus in the Bunyaviridae family, designated SFTS bunyavirus.
They say: "Although we have not fulfilled Koch's postulates for establishing a causal relationship between a microbe and a disease in their entirety, our findings suggest that SFTS is caused by a newly identified bunyavirus."
The team obtained blood samples from patients with SFTS in six provinces in China, which were used to isolate the pathogen responsible through cell culture inoculation.
RNA sequence analysis showed the virus was a newly identified member of the genus phlebovirus in the Bunyaviridae family, and electron microscopy revealed virions with the morphologic characteristics of a bunyavirus.
Viral RNA, or specific antibodies to the virus in the blood, were found in 171 SFTS patients from the six Chinese provinces. In addition, serologic assays showed a virus-specific immune response in all 35 pairs of serum samples collected from patients during the acute and convalescent phases of the illness.
Molecular screening of mosquitoes and ticks was initiated to identify the bunyavirus vector. Of 186 ticks of the species Haemaphysalis longicornis that were collected from domestic animals in areas where the patients lived, 5.4% contained SFTS bunyavirus RNA.
Reporting in the New England Journal of Medicine, the researchers conclude: "Our finding that SFTS [bunyavirus] is the probable cause of a previously unknown severe febrile disease is one of the fruits of heightened surveillance of infectious diseases in China".
"More research is needed to determine the extent to which this disease occurs in regions outside its area of identification."
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By Anita Wilkinson