Ticks Tick Borne Dis. 2019 Oct 17:101310. doi: 10.1016/j.ttbdis.2019.101310. [Epub ahead of print]
Presence of diverse Rickettsia spp. and absence of Borrelia burgdorferi sensu lato in ticks in an East Texas forest with reduced tick density associated with controlled burns.
As tick-borne diseases continue to emerge across the United States, there is need for a better understanding of the tick and pathogen communities in the southern states and of habitat features that influence transmission risk. We surveyed questing and on-host ticks in pine-dominated forests with various fire management regimes in the Sam Houston National Forest, a popular recreation area near Houston, Texas. Four linear transects were established- two with a history of controlled burns, and two unburned. Systematic drag sampling yielded 112 ticks from two species, Ixodes scapularis (n=73) and Amblyomma americanum (n=39), with an additional 106 questing ticks collected opportunistically from drag cloth operators.
There was a significant difference in systematically-collected questing tick density between unburned (15 and 18 ticks/1000 m2) and burned (2 and 4 ticks/1000 m2) transects. We captured 106 rodents and found 74 ticks on the rodents, predominantly Dermacentor variabilis. One unburned transect had significantly more ticks per mammal than any of the other three transects. DNA of Rickettsia species was detected in 146/292 on and off-host ticks, including the ‘Rickettsial endosymbiont of I. scapularis’ and Rickettsia amblyommatis, which are of uncertain pathogenicity to humans. Borrelia lonestari was detected in one A. americanum, while Borrelia burgdorferi sensu stricto, the agent of Lyme disease, was not detected in any tick samples. Neither Borrelia nor Rickettsia spp. were detected in any of the mammal ear biopsies (n=64) or blood samples (n=100) tested via PCR.
This study documents a high prevalence in ticks of Rickettsia spp. thought to be endosymbionts, a low prevalence of relapsing fever group Borrelia in ticks, and a lack of detection of Lyme disease-group Borrelia in both ticks and mammals in an east Texas forested recreation area. Additionally, we observed low questing tick density in areas with a history of controlled burns. These results expand knowledge of tick-borne disease ecology in east Texas which can aid in directing future investigative, modeling, and management efforts.
Though it is caused by one tiny tick bite, the symptoms and subsequent fallout of Lyme disease can be devastating for patients. It is one of the most insidious diseases out there, and it doesn’t seem to be slowing down. Roughly 300,000 new Lyme cases are discovered every year according to the CDC (American Centers for Disease Control and Prevention), and it’s also worth keeping in mind that misdiagnosis rates for the condition are unusually high. Compounding the problem is the fact that chronic Lyme is not a fully legitimate condition in the eyes of most medical bodies, residing in a complicated grey area. A tick bite can also herald other health issues, including co-infections and tick paralysis. These complications can underpin Lyme and compound its effects. But what is tick paralysis? And is tick paralysis a symptom of Lyme disease?
Tick paralysis is transmitted by over 40 species of ticks. It is particularly dangerous for animals, and has caused the death of thousands of livestock over the decades. It is also a threat for domestic animals and can occur in any region where ticks make their home. Fortunately for us, cases are much rarer in humans. The disease usually occurs in children younger than ten, under very specific circumstances. An engorged, egg-laden female tick will produce a neurotoxin in its salivary glands. This neurotoxin is transmitted to the host during feeding, using the saliva of the tick as a conduit. Because such small amounts of saliva make the transition into the host’s bloodstream, research has shown that the most potent form of tick paralysis is transmitted approximately five to seven days after the initial attachment of tick to host.
What’s the connection between tick paralysis and Lyme disease? Read on to find out.
Despite the size of the tick and the tiny volume of saliva being exchanged, symptoms can sometimes be dramatic and concerning. Typical signs and symptoms include ataxia (a neurological sign that causes impaired movement and coordination) and paralysis, which usually starts in the feet or legs and moves upward. Tick paralysis does not include fever or flu-like symptoms, which are common in almost all other tick-borne diseases. The condition can become life-threatening, however, if the paralysis spreads to the torso, as it can hamper crucial organs and muscles, inducing cardiac issues and breathing difficulties. Diagnosis is fairly straightforward: if the individual lives in a tick-heavy area and has sudden-onset ataxia and paralysis in the legs, they should be thoroughly checked for ticks. No individual tests are necessary. So, what to do if you have tick paralysis? Fortunately, treatment is simple. Removing the offending tick will reduce symptoms almost immediately, and there are no residual effects. Patients just have to ensure they remove all parts of the tick from the bite.
This is a crucial difference between tick paralysis and Lyme disease and other co-infections. Tick paralysis can only exist in the presence of the tick, as it is chemically induced by the physical bite. Lyme disease is caused by invading bacteria that the tick actively transfers into the system. Once the bacteria (called Borrelia burgdorferi) invade the host’s system, the residual effects are what form the disease. The tick may be removed successfully when it is noticed, but Lyme disease can still very much be present, as long as it has had time to transfer. Not every tick will cause tick paralysis, and not every tick carries the Lyme-causative bacteria. Unfortunately, though, Lyme disease is much more prevalent than tick paralysis, and is nowhere near as easy to cure.
The first stage of Lyme is known as the acute stage, and it produces symptoms similar to the flu. These are not necessarily severe, meaning many patients underestimate them, or write them off as a mild bout of temporary sickness. The presence of a bullseye rash at the site of the bite is a sure-fire sign of Lyme, but the bite itself is not always noticed by the host. Over a couple of days or weeks, these initial symptoms will clear up, as the disease recedes and lies dormant for a time. Eventually, it will re-emerge as chronic Lyme, which causes a number of generalised, patient-specific symptoms that lend themselves to continued misdiagnosis. At this stage in the disorder, the immune system has kicked into overdrive and is causing symptoms of its own through sustained inflammation. These usually include muscle pains and aches, impaired movement, malaise and chronic fatigue. Bacteria-induced symptoms can include neurological issues and potential cardiac complications.
Aches and pains are a common symptom of chronic Lyme disease.
Treating chronic Lyme is an exceptionally difficult task and requires specialist knowledge from Lyme-literate doctors. Labs like BCA-clinicunderstand that chronic Lyme comes in many varied forms, and that treatment plans have to be tailored to each individual patient. It can be a long, hard road, particularly if additional co-infections are present. These must be addressed and treated simultaneously to ensure there are no residual effects. Fortunately, tick paralysis is not a symptom of Lyme per se, and one is not caused by the other. The two have very different mechanics, with tick paralysis kicking in very soon after a bite, and Lyme disease revealing itself over time. It is, however, vitally important for people to be aware of both of these potentially debilitating disorders, and limit their exposure to ticks when and where they can.
Ticks are masters of breaking down the defenses of their host organism to get a blood meal. They use anesthetics to numb the skin, anticoagulants to keep the blood flowing, and keep the host’s immune system from recognizing them as invaders and kicking them out. And the key to understanding this is in the tick’s saliva. Biochemist and microbiologist Seemay Chou discusses how she milks the saliva from ticks to study what compounds play key parts in these chemical tricks. She also talks about how ticks are able to control the microbes in their saliva.
SciFri took a visit of Chou’s tick lab at UCSF. See photos of the team’s work below…. (See full article & podcast in link above)
“But I am a biologist, so that’s where I started working on ticks and mosquitoes—how to produce a lot of them. Drop them out of airplanes. Everything was very hush-hush, very secret. I’m still leery talking about it, because I think they might put me in jail because I’m delivering secrets. [Laughs.] It was a crazy time.
How do you do a defensive application of ticks and mosquitoes?
We would run all kinds of distribution tests on where these things go when you release them and what were the factors that would cause the migration. Can we drop them out of airplanes and how do we get the bugs to the enemy? That was the thing we did…”
A total of 127 Amblyomma ticks (A. helvolum, A. varanense and A. geoemydae) were collected from reptiles: water monitors (Varanus salvator), Bengal monitors (Varanus bengalensis), Burmese pythons (Python bivittatus), yellow-spotted keelbacks (Xenochrophis flavipunctatus), keeled rat snakes (Ptyas carinata) and elongated tortoises (Indotestudo elongata) from nine provinces in Thailand. The presence of Borrelia spp. of the 16S rRNA, flaB, glpQ, groEL and gyrB genes was examined by conventional, semi-nested and nested PCR. Phylogenetic analyses using maximum likelihood method of housekeeping genes showed that most sequences of Borrelia spp. in these Amblyomma ticks belonged to the clade of reptile-associated (REP) borreliae. Interestingly, one Borrelia sp. in an A. geoemydae tick collected from an elongated tortoise clustered in the same clade as a Borrelia sp. detected from an A. geoemydae-infested turtle in Japan (it may belong to the same species given the identical sequences of their 16S rRNA, flaB and glpQ genes) and formed the same group with tick-borne relapsing fever (RF) borreliae of B. miyamotoi and B. theileri.
Our findings are the first report on the presence of Borrelia spp. in A. helvolum and A. geoemydae ticks from reptiles in Thailand adding to the geographic distribution of Borrelia spp. in Asia.
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**Comment**
Please note the turtle found with a relapsing fever borrelia in the same group as B. miyamotoi and B. theileri – both pathogens that infect humans as well as animals.
RESEARCHERS WORKING AT FORT MCCOY NEAR SPARTA, AS PART OF A MULTI-UNIVERSITY PROJECT MICHIGAN STATE ECOLOGIST JEAN TSAO LEADS, HAVE COLLECTED DEER TICKS FROM FIVE-LINED SKINKS AND SNAKES.
Minimal Duration of Tick Attachment Sufficient for Transmission of Infectious Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) by Its Primary Vector Dermacentor variabilis(Acari: Ixodidae): Duration of Rickettsial Reactivation in the Vector Revisited
It has been reported that starving ticks do not transmit spotted fever group Rickettsia immediately upon attachment because pathogenic bacteria exist in a dormant, uninfectious state and require time for ‘reactivation’ before transmission to a susceptible host. To clarify the length of reactivation period, we exposed guinea pigs to bites of Rickettsia rickettsii-infected Dermacentor variabilis (Say) and allowed ticks to remain attached for predetermined time periods from 0 to 48 h. Following removal of attached ticks, salivary glands were immediately tested by PCR, while guinea pigs were observed for 10–12 d post-exposure. Guinea pigs in a control group were subcutaneously inoculated with salivary glands from unfed D. variabilis from the same cohort. In a parallel experiment, skin at the location of tick bite was also excised at the time of tick removal to ascertain dissemination of pathogen from the inoculation site. Animals in every exposure group developed clinical and pathological signs of infection.The severity of rickettsial infection in animals increased with the length of tick attachment, but even attachments for less than 8 h resulted in clinically identifiable infection in some guinea pigs.Guinea pigs inoculated with salivary glands from unfed ticks also became severely ill.Results of our study indicate that R. rickettsii residing in salivary glands of unfed questing ticks does not necessarily require a period of reactivation to precede the salivary transmission and ticks can transmit infectious Rickettsia virtually as soon as they attach to the host.
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**Comment**
For far too long authorities have told us that there’s something called a “grace period,” in which ticks supposedly delay transmitting pathogens to us and that a period of 24-48 hours is required before we can become infected.
There is only one study which they base that information upon, and there’s never been a study on the minimum time for transmission.
This study blows the “grace period” theory out of the water and proves what we all know to happen in reality. People can become infected in mere hours upon attachment. It also proves another point as well: that some ticks have the pathogens already in their salivary glands making transmission times even shorter.
How many have been sent home with a false sense of security after a doctor, going by information authorities have proliferated, told them they can’t be infected because the tick wasn’t attached for a long enough period of time? Thousands?
Please spread the word. There shouldn’t be any more patients falling through the cracks.
