Asian Longhorned Tick - Credit CDC
#18,772
SFTS or Severe Fever with Thrombocytopenia Syndrome - a tickborne Phlebovirus - was first discovered in China in 2009, but has since been found in Japan, South Korea, Vietnam, and Taiwan.
It is believed be carried and transmitted by the Asian Longhorned tick (along with Amblyomma testudinarium & Ixodes nipponensis).
While SFTS has never been detected in the United States, in 2017 the CDC reported the first detection of its primary vector; the Asian Longhorned tick.
As of April 12, 2024, longhorned ticks have been found in Arkansas, Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.Admittedly, SFTS doesn't pose anywhere near the public health threat of either COVID or avian flu, but this tickborne virus appears to have a fatality rate in humans ranging from the single digits to > 30%, depending on the region.
According to officials, no evidence of a tick bite was found during the autopsy.
Somewhat inexplicably, this is being widely reported as the first suspected animal-to-human transmission of SFTS in Japan. However, nearly 5 years ago the EID Journal reported:
A year earlier (2019), a report in the CMI Journal found that contact with blood or respiratory secretions of an infected patient was linked to infection in multiple HCWs.Atsushi Yamanaka, Yumi Kirino, Sho Fujimoto, Naoyasu Ueda, Daisuke Himeji, Miho Miura, Putu E. Sudaryatma, Yukiko Sato, Hidenori Tanaka, Hirohisa Mekata, and Tamaki Okabayashi
Abstract
Two veterinary personnel in Japan were infected with severe fever with thrombocytopenia syndrome virus (SFTSV) while handling a sick cat. Whole-genome sequences of SFTSV isolated from the personnel and the cat were 100% identical. These results identified a nosocomial outbreak of SFTSV infection in an animal hospital without a tick as a vector.
Nosocomial person-to-person transmission of severe fever with thrombocytopenia syndrome.
Jung IY1, Choi W2, Kim J3, Wang E2, Park SW2, Lee WJ2, Choi JY4, Kim HY1, Uh Y3, Kim YK5.
Results
Among 25 HCWs who had direct contact with the index patient, five HCWs were confirmed to have SFTS. All five HCWs had contact to blood or bloody respiratory secretions of the index patient without adequate use of personal protective equipment (PPE). No HCW with contact before haemorrhagic manifestations of the index patient contracted SFTS. Overall, the transmission rate was higher for HCWs who had contact after the index patient had haemorrhagic manifestations (33.3%, five of 15 HCWs, vs. 0%, zero of ten HCWs, p 0.041).
Conclusions
In HCWs who are inadequately protected, person-to-person transmission of SFTSV may be associated with contact with blood or bloody respiratory secretions. Therefore, universal precaution and full PPE is highly recommended for protection against SFTSV when there are signs of bleeding.
In 2022, in Nosocomial Outbreak of SFTS Among Healthcare Workers in a Single Hospital in Daegu, Korea, we looked a large (17 HCW) outbreak of SFTS at university hospital in 2020.
Although it is impossible to say with absolute certainty that these nosocomial infections were due to airborne transmission of the virus, the authors considered it likely.
And just over a year ago, in Japan Case Report: 1st Human-to-Human Transmission of SFTS in Japan, Japan's Institute for Infectious Diseases published a case report on that country's first confirmed case of Human-to-Human transmission of the virus; from an elderly patient to an attending doctor.
The report recommended:
In the future, in order to prevent human-to-human infections like the one in this case, standard precautions and route-specific precautions should be more thoroughly implemented in accordance with the SFTS clinical practice guidelines4
For those looking for a good epidemiological review of SFTS, earlier this year the Am J Trop Med Hyg published the following open access report.
Sakarn Charoensakulchai 1, Keita Matsuno 2,3,4,5, Emi E Nakayama 6, Tatsuo Shioda 6, Hisham A Imad 1,6,7,*
ABSTRACT.Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease primarily reported in Asia. This review aims to summarize studies on the epidemiological characteristics of SFTS. Literature from PubMed and Scopus was searched up to February 14, 2024. A total of 76 articles were eligible.
Infections were reported in China, Japan, South Korea, and several other countries in Asia. The incidence of SFTS has been rising and reported from new areas across Asia. The incidence rate was highest in China, ranging from fewer than 0.1 to 4.2 cases per 100,000 population and reaching up to 127.6 cases per 100,000 population in some areas.
Most cases occurred between April and December. Elderly farmers and veterinarians were the most affected group. Key epidemiological factors included direct contact with animals, outdoor work, vegetation near homes, rural or hilly residency, tick bites, and direct contact with blood or saliva from infected animals or humans.
Like Lassa Fever, CCHF, Nipah, and even the recently discovered Langya virus, SFTS is one of those relatively obscure zoonotic diseases that - while currently lacking pandemic potential - could conceivably become a bigger public health threat over time.
