Tiny, larval ticks can pack a wallop

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 Lyme Science Blog: Study finds tiny larval ticks can transmit 

Wed Mar 27, 2019 6:43 am (PDT) . Posted by: 

"Rick Laferriere" ri_lymeinfo 

*Study finds tiny larval ticks can transmit /Borrelia miyamotoi/*
/Lyme Science Blog/, by Daniel Cameron, MD, MPH, Mt. Kisco, New York
Dr. Cameron is a nationally recognized leader for his expertise in the 
diagnosis and treatment of Lyme disease and other tick-borne illnesses.

March 25, 2019
http://danielcameronmd.com/study-finds-tiny-larval-ticks-can-transmit-borrelia-miyamotoi/

Nymphal and adult black-legged ticks, also known as deer ticks, harbor a 
growing number of pathogens.

But researchers are now discovering that larval ticks, which are even 
smaller, may pose an equal threat to public safety as a new study 
describes larval ticks infected with the tick-borne bacteria /Borrelia 
miyamotoi/.

*Read the Complete Blog Entry*:
http://danielcameronmd.com/study-finds-tiny-larval-ticks-can-transmit-borrelia-miyamotoi/ 

*Read more of Lyme Science Blog at*:
http://danielcameronmd.com/all-things-lyme-blog-archives/ 
<http://danielcameronmd.com/all-things-lyme-blog-archives/>

*Contact**Dr. Daniel Cameron*:
http://danielcameronmd.com/ <http://danielcameronmd.com/>

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Related reading:
*Vertical transmission rates of /Borrelia miyamotoi/ in /Ixodes 
scapularis/ collected from white-tailed deer *
Han S, Lubelczyk C, Hickling GJ, Belperron AA, Bockenstedt LK, Tsao JI.
/Ticks and Tick-borne Diseases/. 2019 Feb 26. pii: S1877-959X(18)30088-8.

https://doi.org/10.1016/j.ttbdis.2019.02.014

Abstract

/Borrelia miyamotoi/is a relapsing feverspirochetetransmitted by ticks 
in the /Ixodes ricinus/ complex. In the eastern United States, /B. 
miyamotoi/ is transmitted by /I. scapularis,/ which also vectors several 
other pathogens including /B. burgdorferi/sensu stricto.

In contrast to Lyme borreliae, /B. miyamotoi/can be transmitted 
vertically from infected female ticks to their progeny. Therefore, in 
addition to nymphs and adults, larvae can vector /B. miyamotoi/to 
wildlife and human hosts. Two widely varying filial infection prevalence 
(FIP) estimates - 6% and 73% - have been reported previously from two 
vertically infected larval clutches; to our knowledge, no other 
estimates of FIP or transovarial transmission (TOT) rates for /B. 
miyamotoi/have been described in the literature. Thus, we investigated 
TOT and FIP of larval clutches derived from engorged females collected 
from hunter-harvested white-tailed deer in 2015 (n = 664) and 2016 
(n = 599) from Maine, New Hampshire, Tennessee, and Wisconsin.

After engorged females oviposited in the lab, they (n = 492) were tested 
for /B. miyamotoi/infection by PCR. Subsequently, from each clutch 
produced by an infected female, larval pools, as well as 100 individual 
eggs or larvae, were tested. The TOT rate of the 11 infected females was 
90.9% (95% CI; 57.1–99.5%) and the mean FIP of the resulting larval 
clutches was 84.4% (95% CI; 68.1–100%).

Even though the overall observed vertical transmissionrate (the product 
of TOT and FIP; 76.7%, 95% CI; 44.6–93.3%) was high, additional 
horizontal transmission may be required for enzootic maintenance of /B. 
miyamotoi/ based on the results of a previously published deterministic 
model. Further investigation of TOT and FIP variability and the 
underlying mechanisms, both in nature and the laboratory, will be needed 
to resolve this question. Meanwhile, studies quantifying the 
acarological risk of /Borrelia miyamotoi/ disease need to consider not 
only nymphs and adults, but larval /I. scapularis/ as well.

https://doi.org/10.1016/j.ttbdis.2019.02.014