Original article

Failure of the Asian longhorned tick, Haemaphysalis longicornis, to serve as an experimental vector of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto

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The invasive, human-biting Asian longhorned tick, Haemaphysalis longicornis, was detected in New Jersey in the eastern United States in August of 2017 and by November of 2018 this tick had been recorded from 45 counties across 9 states, primarily along the Eastern Seaboard. The establishment of H. longicornis in the United States has raised the questions of how commonly it will bite humans and which native pathogens may naturally infect this tick. There also is a need for experimental vector competence studies with native pathogens to determine if H. longicornis can acquire a given pathogen while feeding, pass it transstadially, and then transmit the pathogen in the next life stage.

In this experimental study, we evaluated the vector competence of a population of H. longicornis originating from the United States (New York) for a native isolate (B31) of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (s.s.).

In agreement with a previous experimental study on the vector competence of H. longicornis for Borrelia garinii, we found that uninfected H. longicornis larvae could acquire B. burgdorferi s.s. while feeding on infected Mus musculus mice (infection prevalence >50% in freshly fed larvae) but that the infection was lost during the molt to the nymphal stage. None of 520 tested molted nymphs were found to be infected, indicating that transstadial passage of B. burgdorferi s.s. is absent or rare in H. longicornis; and based on the potential error associated with the number of nymphs testing negative in this study, we estimate that the upper 95% limit for infection prevalence was 0.73%.

An Ixodes scapularis process control showed both effective acquisition of B. burgdorferi s.s. from infected mice by uninfected larvae and transstadial passage to the nymphal stage (infection prevalence of 80–82% for both freshly fed larvae and molted nymphs). We also observed that although H. longicornis larvae could be compelled to feed on mice by placing the ticks within feeding capsules, attachment and feeding success was minimal (<0.5%) when larvae were placed freely on the fur of the mice.

We conclude that H. longicornis is unlikely to contribute more than minimally, if at all, to transmission of Lyme disease spirochetes in the United States.



Transmission can still happen and if you are the sorry sucker it happens to – it makes all the difference in the world.  Here’s the deal – ticks are not your friends. Take each and every tick bite as seriously as a heart attack.  Little is known about the Asian Longhorned tick but in Asia it’s bite KILLS 15% of those whom contract it. Don’t take this lightly.


Several other human pathogens have been detected in the ticks, but it’s not clear the Asian longhorned species are able to transmit them to humans. They include Anaplasma, Ehrlichia, Rickettsia, and Borreliaspecies. Lyme disease is caused by Borrelia burgdorferi bacteria.

She warned that the organisms are present in states where longhorned ticks have been found and that it’s possible that the tick—known to be an aggressive bitermight be able to transmit Heartland virus, given its close relationship to SFTS virus.

Pritt said it’s clear that the invasive species is here to stay for the foreseeable future, and next steps should include public awareness campaigns that incorporate the new information, easy-to-use resources for labs to identify the tick, and more research to understand the implications of the new findings.

For a great read on this aggressive biter which can clone itself and is found in sunny open locations:  This picture demonstrates how if you brush against a blade of grass a literal cluster bomb of ticks explodes onto you.  To downplay this is really short sighted.three_surprising_4.png-2

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