Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease caused by a virus. First identified in 2009 in China, it is a growing public health concern in several East Asian countries. The illness is primarily transmitted to people through the bites of infected ticks and is characterized by a sudden high fever and a notable drop in blood platelets.
Transmission and Geographic Risk
The primary method of SFTS transmission to humans is through the bite of an infected tick. The main carrier for the SFTS virus is the Asian longhorned tick (Haemaphysalis longicornis). When this widespread tick feeds on an infected animal, it can then pass the virus to a person during a subsequent bite as the virus enters the body through the tick’s saliva.
While tick bites are the most common route, the virus can also spread from person to person, though this is less frequent. This transmission occurs through direct contact with the blood or respiratory secretions of an infected person, putting healthcare workers and family members at higher risk. Animals such as goats, cattle, dogs, and pigs serve as reservoirs for the virus in nature.
SFTS is predominantly found in East Asia and is endemic in China, South Korea, and Japan, with most cases appearing between March and November. The risk is highest in rural, wooded, and hilly areas where the tick vectors thrive.
Identifying Symptoms
The onset of SFTS is sudden, with symptoms appearing 5 to 14 days after a tick bite. The earliest signs include a high fever, profound fatigue, headache, and muscle aches. Many individuals also experience significant gastrointestinal distress, including nausea, vomiting, and diarrhea, which can make early identification challenging.
A defining characteristic of the illness is thrombocytopenia, a marked decrease in blood platelets. Platelets are necessary for normal blood clotting, so a low count increases the risk of bleeding. This can manifest as small red or purple spots on the skin or more significant hemorrhages in severe cases.
Another common laboratory finding is leukopenia, a reduction in white blood cells. The depletion of these immune cells weakens the body’s ability to fight the infection. This combination of fever, low platelets, and low white blood cell counts is a strong indicator of SFTS for doctors in endemic regions.
Diagnosis and Medical Care
If a patient presents with symptoms and has a history of outdoor activities in an endemic area, a doctor may suspect SFTS. Because the clinical signs can resemble other tick-borne illnesses, laboratory confirmation is necessary for an accurate diagnosis. The most definitive method is a reverse transcription-polymerase chain reaction (RT-PCR) blood test, which is highly specific and can detect the genetic material of the SFTS virus directly from a patient’s blood sample.
Currently, there is no specific antiviral cure for SFTS. Medical intervention is primarily supportive, focusing on managing symptoms and preventing complications while the body fights the infection. This includes administering intravenous fluids, monitoring vital signs, and managing any organ dysfunction. The goal is to maintain the body’s functions until recovery begins.
Some antiviral medications, such as Ribavirin, have been used, but their effectiveness remains under investigation. The case-fatality rate can range from 12% to as high as 30% in some outbreaks, which underscores the need for early diagnosis and supportive care.
Prevention Strategies
Preventing SFTS revolves around avoiding tick bites, particularly in regions where the virus circulates. Individuals should avoid walking through wooded and bushy areas with high grass. When spending time outdoors, it is advisable to use an EPA-registered insect repellent with ingredients like DEET or picaridin on exposed skin and clothing.
Wearing protective clothing offers a physical barrier. This includes long-sleeved shirts, long pants, and tucking pant legs into socks or boots to prevent ticks from crawling underneath. After any outdoor activity in at-risk environments, perform a thorough tick check on the entire body, including the scalp, behind the ears, and under the arms, as well as on clothing and gear.
If a tick is found attached to the skin, remove it promptly. Using fine-tipped tweezers, grasp the tick as close to the skin’s surface as possible. Pull upward with steady, even pressure to remove the entire tick without breaking off the mouthparts. After removal, clean the bite area and your hands with rubbing alcohol or soap and water.