Asian Longhorned Tick - Credit CDC
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We've been following the identification, and spread, of a tick borne Phlebovirus - which causes SFTS (Severe Fever with Thrombocytopenia Syndrome) - more more than a dozen years.
While primarily transmitted by the bite of a tick, there is evidence that the virus can also be transmitted from from animals-to-humans (see EID Journal Direct Transmission of SFTS from Domestic Cat to Veterinary Personnel), and from human-to-human (see Nosocomial person-to-person transmission of severe fever with thrombocytopenia syndrome) either through aerosols or close contact with infected body fluids.The virus was first discovered in China in 2009, and has subsequently been found in Japan, South Korea and Vietnam - and in 2019 was detected for the first time in Taiwan.
Aerosol transmission of severe fever with thrombocytopenia syndrome virus during resuscitation
Nosocomial Outbreak of SFTS Among Healthcare Workers in a Single Hospital in Daegu, Korea.
Yesterday 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.
A hat tip to Sharon Sanders on FluTrackers for posting the report. I'll have more after the break.
(translation)
(Breaking news publication date 2024/3/19)
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral infection caused by SFTS virus (SFTSV). Patients who develop SFTS experience sudden fever, gastrointestinal symptoms such as diarrhea and melena, as well as decreased platelets and white blood cells, and severe cases develop multiple organ failure and die. The fatality rate in Japan is as high as 27% 1) , and to date there is no established specific treatment for SFTS. The main route of infection is thought to be through tick bites, but cases of human-to-human transmission have been reported from China and South Korea2 ) . Since the first SFTS patient was reported in Japan in 2013 ( 3) , no human-to-human infection has been observed in Japan, but here we report the first case of human-to-human infection in Japan.
Case
Doctor A was a man in his 20s who worked at our hospital. In April 2023, a male patient in his 90s visited our hospital's emergency department with anorexia, fever, and difficulty moving. Doctor A wore a surgical mask to interview the patient and performed a physical examination without gloves, but did not perform any examination or treatment that would involve direct contact with the patient's body fluids. Blood tests revealed decreased white blood cells, decreased platelets, and elevated levels of LDH and liver enzymes, and SFTS was suspected, so the patient was rushed to the hospital, and Doctor A became the attending physician. After admission, another doctor put on a cap, goggles, surgical mask, gown, and single-layer gloves, and inserted a central venous catheter. Patients were kept in private rooms, and medical staff wore goggles, surgical masks (or N95 masks), gowns, and single gloves.
The patient was diagnosed with SFTS the next day after being admitted to the hospital, but later developed impaired consciousness and convulsions, his general condition rapidly deteriorated, and he died within 3 days. After the death, Doctor A, wearing a surgical mask, gown, and single gloves, removed the indwelling central venous catheter and sutured the site where it had been removed, where bleeding had been difficult to stop. He was not wearing goggles at the time. Furthermore, no needle stick accidents occurred during suturing procedures.
Eleven days after the first contact with the patient (9 days after the patient's death), Doctor A noticed a fever of 38°C and a headache. Arthralgia, diarrhea, loss of appetite, and dry cough gradually developed, and a blood test 5 days after onset revealed abnormal findings suggestive of SFTS (white blood cells 2000/μL, platelets 7.8×10 4 / μL , AST 76 IU/ L, LDH 276 IU/L), an RT-PCR test for SFTSV was performed, leading to a definitive diagnosis of SFTS. Symptoms gradually improved with follow-up observation, and blood test findings improved on the 12th day after onset. Doctor A had no history of outdoor activities that would have resulted in tick bites before the onset of SFTS, and had no history of keeping pets.
The virus copy numbers detected by reverse transcription real-time PCR in serum samples from patient and doctor A were 7.2 x 10 6 copies/mL and 3.9 x 10 2 copies/mL, respectively. When each SFTSV gene was sequenced and compared using the Sanger method and a next-generation sequencer, the sequences of the M segment (661 bases from 1382nd to 2042nd in the viral complementary strand RNA) and S segment (virus 100% homology was observed in the complementary strand RNA (263 bases from position 389 to position 651). Since both SFTSVs were thought to be the same virus, it was diagnosed as a case of human-to-human infection from the patient to Doctor A.
No symptoms suggestive of SFTS infection were observed in other healthcare workers who came into contact with the patient. While the patient was hospitalized, family members wore surgical masks, gowns, and gloves during visits. Funeral workers who transported the body from the hospital to the home wore only masks and gloves. Afterwards, we checked with the public health center in the area surrounding our hospital, and found that there were no reports of infection among the patient's family or those involved in the funeral.
Inspection
Although there have been multiple reports of human-to-human transmission of SFTS from China and South Korea2 ) , this case is the first case of human-to-human infection in Japan. Regarding the use of personal protective equipment in medical settings when treating patients with SFTS, in addition to masks and eye guards to protect mucous membranes, double gloves and an apron are worn on the fingers and front of the trunk, which are easily contaminated with blood and body fluids. is recommended4 ) . Furthermore, it is recommended to wear an N95 mask when performing activities that may generate aerosols, such as cardiopulmonary resuscitation or endotracheal intubation.
From the interviews regarding this case, two possibilities were raised as to how the infection could have been transmitted from the patient to the doctor. The first was the first visit to the emergency department, during which the patient was examined wearing only a surgical mask, and the second was during the post-mortem procedure.
In particular, during the postmortem procedure, Doctor A wore single gloves, a gown, and a surgical mask, but did not use eye guards. Central venous catheter removal and suturing procedures provided opportunities for exposure to blood, although not directly. It was also thought that the patient may have contracted the infection through droplets from the conjunctiva, or may have come into contact with blood while removing personal protective equipment.
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 ) . In particular, if the patient is seriously ill like the one in this case, invasive procedures such as central venous catheter insertion and hemostasis may be performed. If there is a possibility of blood scattering during such procedures, medical personnel should be reminded to take thorough infection prevention measures, such as providing eye protection (face shields, eye guards, etc.).
Additionally, a report examining SFTS cluster infections found that contact with blood from dead bodies has a higher risk of infection5 ) . If there is a possibility of blood scattering during post-mortem treatment, similar infection control measures must be taken.
Also known as the Dabie bandavirus, SFTS 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 the Asian Longhorned tick in North America. Their most recent update states:
As of April 13, 2023, longhorned ticks have been found in Arkansas, Connecticut, Delaware, Georgia, Indiana, Kentucky, Maryland, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.
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 easily become a bigger public health threat over time.
