Range Expansion of Tick Disease Vectors in North America: Implications for Spread of Tick-Borne Disease

Int. J. Environ. Res. Public Health 2018, 15(3), 478; doi: 10.3390/ijerph15030478

Daniel E. Sonenshine 1,2
Published: 9 March 2018

Abstract : Ticks are the major vectors of most disease-causing agents to humans, companion animals and wildlife. Moreover, ticks transmit a greater variety of pathogenic agents than any other blood-feeding arthropod. Ticks have been expanding their geographic ranges in recent decades largely due to climate change. Furthermore, tick populations in many areas of their past and even newly established localities have increased in abundance. These dynamic changes present new and increasing severe public health threats to humans, livestock and companion animals in areas where they were previously unknown or were considered to be of minor importance. Here in this review, the geographic status of four representative tick species are discussed in relation to these public health concerns, namely, the American dog tick, Dermacentor variabilis, the lone star tick, Amblyomma americanum, the Gulf Coast Tick, Amblyomma maculatum and the black-legged tick, Ixodes scapularis. Both biotic and abiotic factors that may influence future range expansion and successful colony formation in new habitats are discussed.


The introduction to this paper points out ticks cause 95% of the vector-borne diseases reported annually in the U.S., and out of 900 species, about 25 are causing the damage.

Interestingly, the author states vector ticks have a well-defined geographic range due mostly to environmental factors; however, this “rule” of thumb” continues to be broken day after day.  Plainly stated, ticks that shouldn’t be in certain areas now are.  This of course means animals and people are going to be infected.  

But to be honest, this “rule of thumb” has been broken repeatedly in the past but because researchers and the CDC stated only certain ticks are in certain locations, people were dismissed and they limped away undiagnosed and untreated and went on to develop severe illness.

Here’s an example:  In short, there’s a lot of unbelievable things that went on to deny Lyme was in the South.

Recently, Asian ticks popped up in New Jersey – a tick, by the way, that clones itself:  Now that’s not supposed to happen…..but happen it did.

Another recent development is the discovery that ticks bite ticks:  The take home here is that ticks could theoretically pass pathogens on to each other as well as the fact,

“Male ticks that were infected with a pathogen or parasite—(such as Lyme disease spirochetes or Babesia protozoans—previously during their life cycle, by feeding on an infected host, could transmit these pathogens to female ticks during hyperparasitism. Female ticks could then transfer these pathogens or parasites to their progeny by transovarial transmission,” Durden says. “Although we don’t know yet if pathogen or parasite transmission occurs between I. angustus ticks by these mechanisms, if it does occur, this could have epidemiological significance by amplifying the number of infected ticks.”

And lastly, is the fact the CDC/IDSA/NIH STILL hasn’t acknowledged the implication of coinfections to the Lyme/MSIDS picture.  People go in, get their 21 days of doxycyline, and very well could be coinfected with things doxy will not kill – Babesia for instance.

They also still deny the possibility of many of these pathogens being sexually and congenitally transmitted:

And there are potentially other means of transmission as well…..

All together, these factors add up and build a mountain.  Meanwhile patients are at the bottom of the mountain with a fork to climb it.

And climate change has absolutely NOTHING to do with it: