Severe fever with thrombocytopenia syndrome

• Cause: severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne hemorrhagic viral disease of humans. It is believed to be caused by a tick borne Phlebovirus of the family Bunyviridae, transmitted by the tick Haemaphysalis longicornis, and it can be fatal to affected people. Cattle, and other domestic and wild animals, are believed to be amplification vectors for this disease, although they do not suffer the disease themselves. Research into this emerging condition and the role of cattle in the transmission of this disease is ongoing.
• Signs: SFTS is an asymptomatic disease in livestock.
• Diagnosis: RT-PCR, IgG ELISA and virus isolation have demonstrated circulating virus in domestic livestock species during epidemiological investigations in regions where human cases of SFTS have occurred.
• Treatment: none, no clinical signs have been reported in livestock.
• Prognosis: good, no clinical signs have been reported in livestock.

Presenting signs

• None.
• SFTS is an asymptomatic disease in livestock.

Geographic incidence

• Eastern Asia to include China, Japan and South Korea.

Public health considerations

• SFTS is a potentially fatal viral hemorrhagic disease of humans responsible for mortality rates of 12-30% in infected individuals.
• Clinical signs in humans include fever, gastrointestinal signs, headache and myalgia followed by thrombocytopenia, leukopenia and in some instances, multi-organ failure and death.
• Mortality is often associated in those individuals over 70 years of age.
• Many species of wild and domestic animals can act as hosts for the tick vector, H. longicornis Asian longhorned tick , and they can also be asymptomatic carriers of the thrombocytopenia syndrome virus (SFTSV). Indirect transfer of the virus via ticks is the most likely explanation for the results of case control studies, which suggest that living and working with domestic animals as a risk factor for human disease, but direct transfer through fomites cannot be ruled out. As such, cattle and other domestic ruminants may be disease amplifiers for infection in humans and vector species alike.

Cost considerations

• None, no clinical signs have been reported in livestock.