Asian Longhorned Tick - Credit CDC
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Although respiratory viruses are our biggest pandemic concern, over the past 10 or 15 years we've seen a number of newly discovered tick-borne diseases emerge which can pose local, or regional, public health threats.
Examples include the `Heartland Virus' (see New Phlebovirus Discovered In Missouri) and the `Bourbon Virus' (see CDC & EID Journal On The Recently Discovered Bourbon Virus) in the United States, and the Dabie bandavirus which causes SFTS in Asia.
SFTS or Severe Fever with Thrombocytopenia Syndrome was first diagnosed in China in 2009, but since been detected in Japan, South Korea, and Taiwan. The Dabie bandavirus 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, it is genetically similar to the Heartland Virus. In 2017 the CDC reported the first detection of the Asian Longhorned tick in the United States. Their most recent update now reports finding it in 18 states:
As of August 26, 2022, longhorned ticks have been found in Arkansas, Connecticut, Delaware, Georgia, Kentucky, Maryland, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.
According to Clinical Update of Severe Fever with Thrombocytopenia Syndrome, published in 2021 in the journal Viruses, SFTS has a high case fatality rate; . . . an average fatality rate of approximately 20% has been reported for SFTS patients, and no treatment strategy has been established.
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) presumably through close contact with infected body fluids.There have also been reports suggestive of potential aerosol transmission of the virus (see Aerosol transmission of severe fever with thrombocytopenia syndrome virus during resuscitation).
Adding to our knowledge base on this emerging infection, we have a dispatch published last week in the EID Journal that documents the nosocomial spread of SFTS - likely via a contaminated pulse oximeter probe - at an animal hospital in Japan.
Volume 29, Number 3—March 2023
Dispatch
Nosocomial Severe Fever with Thrombocytopenia Syndrome in Companion Animals, Japan, 2022
Hirohisa Mekata, Kazumi Umeki, Kentaro Yamada, Kunihiko Umekita, and Tamaki Okabayashi
Author affiliations: University of Miyazaki, Miyazaki, Japan (H. Mekata, K. Yamada, K. Umekita, T. Okabayashi); Kyushu University of Health and Welfare, Nobeoka, Japan (K. Umeki); University of Miyazaki Hospital, Miyazaki (K. Umekita)
Abstract
In Japan, 2 cats that underwent surgery in a room where a sick dog had been euthanized became ill within 9 days of surgery. Severe fever with thrombocytopenia syndrome virus was detected in all 3 animals; nucleotide sequence identity was 100%. Suspected cause was an uncleaned pulse oximeter probe used for all patients.
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging and mostly fatal tickborne zoonosis in eastern Asia. The causative agent is Dabie bandavirus, of the family Phenuiviridae and genus Bandavirus, and is generally known as SFTS virus (SFTSV). In Japan, SFTS-related mortality rates are reported to be 27% among humans and 62% among domestic cats (1,2). Although dogs can become infected with SFTSV, the mortality rate is unclear because infection of healthy dogs tends be subclinical (3).
SFTSV is transmitted to humans and animals primarily through tick bites. However, nosocomial infection without a tick bite can occur via contact with blood and body fluids (4). Human-to-human transmission from an index patient to healthcare workers has been reported (4). Animal-to-human transmission from an index animal to veterinary personnel has also been reported (5,6). We report a nosocomial animal-to-animal transmission of SFTSV.
The Cases
Figure 1. Timeline of dog-to-cat nosocomial transmission of SFTSV, Japan, 2022. Cat 1 was 7 months of age; cat 2 was 21 months of age; dog 1 was 13 years of age....(SNIP)
Conclusions
We report molecular evidence of nosocomial transmission of SFTSV among companion animals in an animal hospital in Japan. Veterinary personnel should be aware of the risk that this emerging zoonotic disease poses for their safety as well as the safety of patients and clients. To prevent nosocomial infections, veterinary staff should be educated about basic infection prevention and control practices in animal hospitals.
While this report deals with companion animals at a veterinary hospital, last year in Nosocomial Outbreak of SFTS Among Healthcare Workers in a Single Hospital in Daegu, Korea, we looked at the investigation into a large outbreak (n=17 HCWs) of SFTS in a South Korean hospital in 2020 following a cardiopulmonary resuscitation (CPR) attempt.
A total of 17 HCWs infected with the SFTS virus (SFTSV) (28.8%) were identified among the 59 HCWs who had contact with the patient.
Although it was impossible to say with absolute certainty that these infections were spread via airborne transmission of the virus, the authors considered it likely. And even though this outbreak occurred during the first year of COVID, they cite a inconsistent PPE compliance as a contributing factor.
We've seen similar reports with Crimean-Congo Hemorrhagic Fever - another tick borne disease found primarily in Eastern Europe, the former Soviet Union, the Mediterranean, in northwestern China, central Asia, southern Europe, Africa, the Middle East, and the Indian subcontinent.
One of the realities of life in this third decade of the 21st century is that the world is much smaller place than it used to be. Disease threats that have previously been limited to Eastern Asia or Africa can board an airliner and be anywhere in the world in 24 hours.
In 2005 we saw the Chikungunya virus break out of Africa, aided and abetted by a fortuitous mutation, and begin its world tour. In 2009, Dengue returned to South Florida after a 70 year absence, undoubtedly brought in by a traveler, much in the same way that West Nile Virus was introduced to North America in 1999 (see below)
From the USGS Factsheet on West Nile Virus
While SFTS and CCHF aren't currently threats here in North America, history has shown that given half a chance, viruses find a way.
Which makes learning more about how they are transmitted a high priority.
