The Ability of the Invasive Asian Longhorned Tick Haemaphysalis Longicornis (Acari: Ixodidae) to Acquire and Transmit Rickettsia Rickettsii (Rickettsiales: Rickettsiaceae), the Agent of Rocky Mountain Spotted Fever, Under Laboratory Conditions

2020 Apr 27;tjaa076.
doi: 10.1093/jme/tjaa076. Online ahead of print.
  • PMID: 32338290


The invasive Asian longhorned tick, Haemaphysalis longicornis Neumann, was first detected in the United States in 2017. It has since been found in 12 states, and there is concern that the tick’s parthenogenetic ability and wide variety of host species may allow for broader dissemination. Of the tick-borne diseases endemic to the United States, Rocky Mountain spotted fever (RMSF), a rapidly progressive and potentially fatal disease caused by Rickettsia rickettsii, is the most severe. There is considerable geographical overlap between spotted fever rickettsioses cases, which include RMSF, and the currently known distribution of H. longicornis, providing the potential for this tick to encounter this pathogen.

We have evaluated the ability of H. longicornis to acquire and transmit R. rickettsii under laboratory conditions. Haemaphysalis longicornis as larvae and nymphs acquired the pathogen while feeding on infected guinea pigs. The infection persisted through every life stage, all of which were able to transmit R. rickettsii to naïve hosts. The pathogen was also transmitted at a low frequency between generations of H. longicornis through the ova. While H. longicornis was demonstrated to be a competent vector for R. rickettsii under laboratory conditions, the probability of its involvement in the maintenance and transmission of this pathogen in nature, as well as its potential impact on human health, requires further study.



The Asian Long-horned tick used to be known as pretty much just a livestock pest.  Obviously, researchers are changing their tune.  What makes this tick particularly unique and equally terrifying is its ability to reproduce through cloning – making a literal infestation very quickly. It is traipsing through the entire U.S. – having been found in at least 12 states.

Here we see it can also transmit Lyme (although they say “minimally” – whatever that means)

The pressing question is what all do they transmit?  We know this so far:  

It spreads SFTS (sever fever with thrombocytopenia syndrome), “an emerging hemorrhagic fever,” causing fever, fatigue, headache, nausea, muscle pain, diarrhea, vomiting, abdominal pain, disease of the lymph nodes, and conjunctival congestion, but the potential impact of this tick on tickborne illness is not yet known. In other parts of the world, this Longhorned tick, also called the East Asian or bush tick, has been associated with several tickborne diseases, such as spotted fever rickettsioses, Anaplasma, Ehrlichia, and Borrelia, the causative agent of Lyme Disease.

For a 2016 literature review on SFTS:
Although the clinical symptoms of SFTS and HGA are similar to each other, but the treatment methods of the two diseases are totally different. Doctors notice that the biggest difference between the clinical symptom of SFTS and HGA is that SFTS patients generally without skin rash, the dermorrhagia is also not seriously, and few massive hemorrhage cases were reported [23]. It is also reported that SFTS patients had gastrointestinal symptoms, such as nausea, vomiting, and diarrhea, which are rarely observed in HGA patients [2]. So these differences can be used as the auxiliary basis of differential diagnosis.
At present, there is still no specific vaccine or antiviral therapy for SFTSV infection. Supportive treatment, including plasma, platelet, granulocyte colony stimulating factor (GCSF), recombinant human interleukin 11, and gamma globulin is the most essential part of case treatment [44]. Meanwhile, some measures were taken to maintain water, electrolyte balance and treat complications are also very important.
Ribavirin is reported to be effective for treating Crimean-Congo Hemorrhagic Fever (CCHF) infections and hemorrhagic fever with renal syndrome, but it is still inadequate to judge the effect of ribavirin on SFTS patients because of the study limitation without adequate parameters were investigated [45]. Host immune responses play an important role in determining the severity and clinical outcome in patients with infection by SFTSV.
For Viral treatment options:

And lastly, please know ticks parasitize one another, potentially spreading all manner of diseases to humans.  This fact also shoots holes in the regurgitated mantra that only certain ticks carry certain pathogens.  If they are feasting on one another, they can potentially infect each other and then us:

And now it appears to have the ability at least in a lab setting to transmit RMSF.  For more:





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