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Having recently read David Quammen’s terrific book on emerging infectious diseases called `Spillover’ (see EID Book Review – Spillover), I may be hyper-sensitized to any odd reports of newly emerging pathogens.
Nevertheless, this next story – which involves a recently discovered virus showing up in a new country – is unusual enough to merit mention.
Today the Mainichi is reporting that a Japanese adult – without recent travel history outside of the country – died last fall from a recently discovered viral infection called SFTS (Severe Fever with thrombocytopenia syndrome) that until now, has only been seen in China.
SFTS – linked to a recently discovered Bunyavirus - is believed to be transmitted primarily by ticks. Outbreaks were first identified in central China's Hubei and Henan provinces during the spring and summer of 2009.
We got our first real look at this syndrome from the NEJM in 2011 (see Fever with Thrombocytopenia Associated with a Novel Bunyavirus in China). At that time, they stated `There was no epidemiologic evidence of human-to-human transmission of the virus.’
For more details on that NEJM report, I would invite you to read Lisa Schnirring’s excellent summary for CIDRAP NEWS (Chinese researchers link febrile disease to new virus).
Since then, in February of 2012, the journal Vector Borne Zoonotic Diseases carried this game-changing report:
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a newly discovered bunyavirus, SFTS virus (SFTSV), and causes high fatality (12% on average and as high as 30%). The objective of this study was to determine whether SFTSV could be transmitted from person to person.
We analyzed sera of 13 patients from two clusters of unknown infectious diseases that occurred between September and November of 2006 in Anhui Province of China for SFTSV antibody by indirect immunofluorescence assay and for SFTSV RNA by RT-PCR. We found that all patients (n=14) had typical clinical symptoms of SFTS including fever, thrombocytopenia, and leukopenia and all secondary patients in both clusters got sick at 6-13 days after contacting or exposing to blood of index patients.
We demonstrated that all patients in cluster 1 including the index patient and nine secondary patients and all three secondary patients in cluster 2 had seroconversion or fourfold increases in antibody titer to SFTSV and/or by RT-PCR amplification of SFTSV RNA from the acute serum. The index patient in cluster 2 was not analyzed because of lack of serum. No person who contacted the index patient during the same period, but were not exposed to the index patient blood, had got illness.
We concluded that SFTSV can be transmitted from person to person through contacting patient's blood.
The question now is how did an adult male in Japan contract this never-reported-before-in-Japan virus?
One might surmise that he came in contact with the blood of an infected individual who had recently visited China . . . but today’s report states that:
Genetic studies show the virus that killed the Japanese occurred in Japan and did not come from China, the ministry said.
Which if correct, creates a bit of an epidemiological puzzle for public health experts to investigate.
Note: A h/t to Makoto on Twitter for the link.