Severe fever with thrombocytopenia syndrome virus or SFTSV is a tick-borne virus commonly found in the northeast regions of China. In recent years, it has also spread to Korea, Japan, Vietnam, and there have been cases reported in the United States. SFTSV was first discovered in China in 2009; this relativeness newness means research about the virus is still ongoing and many things about it remain unconfirmed. 

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Signs and Symptoms 

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The main symptoms of SFTSV include high fever, thrombocytopenia (low platelet count), vomiting, diarrhea, leucopenia (low white blood cell count), and elevated liver enzyme level. In serious cases the virus can also lead to multiple organ failure. SFSTV also has a mortality rate ranging from 12% to 30%, depending on the region. 

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In addition, SFTSV is known to infect animals. It can affect farm animals like cattle, goats, sheep, and chicken, as well as companion animals like dogs and cats. Less has been studied about the disease in animals, especially because animals with SFTSV show much milder symptoms than humans. 

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It’s also possible that SFTSV can be transmitted from animals to humans – without a human having been bitten by a tick. In one case in Japan, a woman died after being bitten by a stray cat, from what doctors believe was a tick-borne disease. https://www.bbc.com/news/world-asia-40713172 Cases like these prompt researchers to wonder about methods of transmission for relatively new diseases like SFTSV. 

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What Bacterium Causes SFTSV? 

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SFTSV is caused by a virus, not a bacterium. Specifically, it is a member of the phlebovirus genus. SFTSV is the most recently discovered virus in the Phleobvirus genus. There are eight viruses total that cause human disease, including Alenquer, Candiru, Chagres, Naples, Punta Toro, Rift Valley fever, Sicilian, and Toscana viruses. 

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When it was first documented, there were no records of human-to-human transmission of the disease. Doctors believed that only an infected tick bite could transfer the virus to a human. However, a study on this virus concluded that transmission could be possible by coming into contact with an infected person’s blood. 

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Which Tick Carries SFTSV? 

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SFTSV has been linked to the Asian longhorned tick, which is the primary vector. This tick species has a worldwide distribution, with confirmed sightings in the United States since 2017. In Asia and Australia, this tick prefers farm animals as hosts, particularly cattle. Indeed, many cases of SFTSV studied in China were found to be farmers or people who worked closely with animals. Asian longhorned ticks will also attack dogs and cats. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5795044/#B36 

 

Asian longhorned ticks are also common parasites for migratory birds throughout the Asia-pacific region. SFTSV can therefore spread to other areas by this means. 

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SFTSV epidemiology in the U.S. remains a bit of a mystery since Asian longhorned ticks are fairly new to the United States. Not much is known about the pathogens they spread in North America. One case of a bite from an Asian longhorned tick has been confirmed so far – in New York state in 2019. 

 

Cures and Treatments 

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There aren’t cures or vaccines for SFTSV and it cannot be treated with antibiotics since it’s a viral infection. Since its discovery, researchers have been working on a vaccine for the disease but it’s not yet available. Ultimately, patients who have SFTSV are treated with ribavirin, steroids, or plasma exchange. Patients’ water and electrolyte levels are also closely monitored and maintained. 

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Recovery from SFTSV varies and treatment options are limited since so little is known about the disease. SFTSV does have the potential to be severe and even life-threatening for both humans and animals. The prognosis for SFTSV depends on how early treatment begins and other risk factors like previous medical history. 

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Areas in Danger of Being Bitten 

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Although the Asian longhorned tick, the vector for SFTSV, is not common in the United States, it is still present. Not much is known about their preferred habitats on the North American continent, but it’s believed that they like both short-grassy meadows and tall-grass woodlands. If you live near these areas, or areas likely to be tick habitats, then you should take great care when venturing outdoors. 

 

Since there’s little data about the Asian longhorned tick’s distribution in the U.S. That said, the Asian longhorned tick has been reported in Connecticut. Also, the first case of one of these ticks biting someone was reported in the Northeast – in New York. 

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Final Thoughts 

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Since SFTSV is a potentially severe and even fatal disease with limited treatment options, public health officials recommend prevention as the number-one method to ward off this disease. It’s best to avoid potential tick habitats and to cover your body when you go outdoors. You should also consider using repellent and ensure that you check yourself and your pets when you return home. 

 

See the CDC’s website for more info about tick prevention. https://www.cdc.gov/ticks/avoid/on_people.html