Dr. Rebecca Trout Fryxell is a medical and veterinary entomologist, researcher and associate professor at the University of Tennessee and joins us from Knoxville, Tennessee. In this episode, Dr. Trout Fryxell talks about tick biology, tick populations in the southeastern US, and strategies to keep ticks away from people in our backyards and school yards.
Small creatures, big impact
Dr. Trout Fryxell became interested in Veterinary entomology when she learned that even a very small organism, such as a caterpillar, could have a very big impact on something many times its size such as a horse. That sparked her interest to study vectors such as mosquitoes, ticks and flies with the aim of helping to reduce the harm they can cause. She explains that a vector is an arthropod that acts as a bridge for a pathogen to move from point A to point B.
There are several unique features of a tick’s biology that enables it to become a vector for various pathogens. One of those features is the hypostome, which is the barbed mouthpart of a tick that allows the tick to attach and remain attached, creating a pathway between itself and its host. Dr. Trout Fryxell explains that the posterior of the tick has something called a festoon, which helps to identify the different species of ticks.
“The hypostome is the part of the tick that actually attaches to you and creates a little cement layer.”Dr. Rebecca Trout Fryxell
Dr. Trout Fryxell’s approach to teaching, teasing out fact from fiction in her work, is to seek out answers by experimentation. She recalls an experiment that one of her colleagues did which involved exploring the tree canopy in order to see whether ticks were perched there waiting to “jump” onto a host. The results confirmed that ticks don’t jump, rather they wait at the end of grasses and shrubs for a host to brush up against them. Another clue that they don’t jump is that their legs look different from other insects that jump, such as grasshoppers and fleas.
“Normally I like to [examine myths] the way most of us do it all the time if we have a question. You know, let’s just do a small experiment and see what those results are.”Dr. Rebecca Trout Fryxell
How not to become a host
One way to collect ticks for surveillance and research is to “drag” for them outdoors using fabric. Dr. Trout Fryxell explains that ticks extend their front front legs, which contain an organ called a tarsus. The tarsus houses something called a Holler’s organ, which is a sensory organ that ticks use to “smell” their host. Dr. Trout Fryxell explains that tick surveillance can be a hazardous job and that different states have different guidelines regarding protection in the field. She recommends wearing light coloured clothing, light coloured socks tucked into pants, shirts tucked into pants, wearing hair up, and wearing treated shoes and pants in order to repel ticks.
Lone star ticks and alpha gal
Dr. Trout Fryxell points out that Lone star ticks are the most abundant tick in the Southeastern US. She explains that they display aggressive behaviour, in that they seek out hosts rather than waiting for them to walk by like many other ticks. The female can be identified by a white spot on her back, and may produce 100-300 larvae at a time. Dr. Trout Fyxell explains that some people experience an allergic response called Alpha gal syndrome in response to a Lone Star tick bite. She explains that the human immune system responds to the alpha gal from the tick, develops an immune response, and in some cases, may develop an immune, or allergic, reaction to red meat (which also contains alpha gal). She reports that some people recover from this syndrome, while others can never go back to eating red meat.
“Alpha gal is an allergic response…after an individual is exposed to a tick bite, their immune system is going to respond to that tick bite…later on an individual who is bitten by one of those Lone star ticks, might consume some red meat, and red meat has alpha gal in it as well.”Dr. Rebecca Trout Fryxell
Rickettsia: more research is needed
Dr. Trout Fryxell touches on another tick-borne illness, Rickettsia. She explains that this bacteria is very common in the southeastern United States. Once believed to be carried only by American dog ticks, it is now known that there are many species of Rickettsia that can be transmitted by several different kinds of ticks. She points out that, although our knowledge base regarding black legged ticks and Lyme disease has increased over the years, there is still much to learn about different tick species and the pathogens they carry.
“We used to think of it as being only one species of Rickettsia, Rickettsia rickettsii, causing Rocky Mountain spotted fever primarily transmitted by the American dog ticks, but now we know there’s multiple Rickettsia species with multiple Rickettsia vectors…it’s a problem definitely worth studying, and I don’t think we know as much about it as we should.”Dr. Rebecca Trout Fryxell
Tick proofing our backyards and school yards
To reduce tick populations around our homes and schools, Dr. Trout Fryxell encourages people to develop different zones for people and wildlife. Creating areas with reduced vegetation and adding fences can help keep animals such as mice and deer separate from humans. Dr. Trout Fryxell also recommends a gravel buffer zone of about 1-2 meters wide and keeping grass low by mowing the lawn. She encourages us to be conscious of where wildlife are most abundant, and to do tick checks after visiting those areas.
“We’ve noticed that by keeping the vegetation low, mowing, having an area where wildlife can be and an area where we can be does minimize our tick bites and tick encounters.”Dr. Rebecca Trout Fryxell
Best practices in education
Dr. Trout Fryxell elaborates on the topic of tick collecting and surveillance around schools and the potential for protocols around tick encounters at school. She notes that, if ticks have been removed at school, they should be placed in a zip lock bag with the date written on it and sent home with the student. Schools could also provide information about what signs and symptoms to look for after a tick bite. She recalls a time when her son was bitten by a tick at school, and the tick was removed and discarded at school. This became a teaching opportunity for the school, and a recognition of the need for better policies around tick encounters at school.
New tick on the block: the Asian longhorn tick
Dr. Trout Fryxell explores emerging research in her area regarding the “new tick on the block,” the Asian Longhorned tick. It is similar to the Lone star tick in Tennessee in its abundance, but unlike other ticks, which take 2 or 3 years to go from egg to adult, the Asian longhorned tick goes from egg to adult in only one year! In addition, over 15,000 Asian longhorned ticks have been collected in Tennessee to date, and all of them are female. She explains that they are parthenogenetic, which means that these female ticks don’t need a male to mate. They can transfer pathogens to animals such as cattle, and in Asia they are known to transmit pathogens to humans.
Awareness is prevention
Dr. Trout Fryxell stresses the importance of being aware of and understanding tick populations, and reiterates the importance of using tick management strategies. Thank you Dr. Fryxell for teaching us (and your students) about ticks, and about ways to keep ourselves and our children safe in the outdoors.
Get an education grant
For physicians and healthcare professionals! Are you a doctor, nurse, physiotherapy, or an accredited healthcare professional? See our eligibility requirements and find out more.