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Long Distance Hikers and Ticks

Dealing with Ticks while Hiking
In the United States, over 26,000 cases of tick vectored disease occur every year. Severe debilities and death sometimes result. Long distance hikers live where the ticks live for months at a time. We need to practice tick avoidance strategies, be aware of any tick bites we have incurred, and consider whether developing health issues may be related to tick exposure. Informing a doctor that symptoms may be related to ticks may save years of suffering from undiagnosed disease.

Ticks feed on blood at all phases of life. They never consume plants as do mosquitoes, etcetera. A full life cycle is two months in some species and several years in others. They feed on humans and other animals at Larval, Nymph and Adult stages. The differences in sizes and shapes at various life stages make it difficult to identify the species of the tick based on size or appearance. It also means that one tick takes three or more blood meals from various hosts over a lifetime. This in turn means that the tick has many chances to acquire disease in various feedings before it finds and infects you. Pathogens may be passed between tick generations in eggs and sperm, so that even with no infected hosts, ticks can transmit disease.

Many species of ticks who feed on humans also feed on rodents, deer, dogs, horses, and other mammals. Diseases which thrive in mammals are much more likely to thrive in humans than illnesses of birds, reptiles, etcetera. It makes sense, then, not to rest or camp at rodent tunnels or rodent infested cabins, or in deer bedding spots, or other areas frequented by mammals. If you do, you're making it easy for a tick who came off another mammal host to crawl onto you.

Ticks can climb up grass stalks, bushes, etcetera, and grab onto hikers as they brush through. Then they may crawl to a spot such as under a belt or pack strap, or an armpit or crotch. In these spots, the tick is held in place by the strap, etcetera, and the skin is often often moist and soft, so ticks can easily hang on and dig into your skin. I have learned to pay close attention to any sensation of something crawling on me. I stop and examine the affected body part. Once I know the area has active ticks, I can pay even closer attention and I can stop periodically and remove them. If another hiker is around, that makes tick checks a bit easier.

If they are still crawling around, just pull them gently off and toss them aside. Since they haven't bitten, they probably have not transmitted disease to you.

The tick, after finding a good spot, begins to attach by burrowing its mouthparts into your skin. If you pull gently, you'll notice that rather than just coming off, the tick is firmly enough attached to pull the skin up a bit. After this point, tick removal takes a bit more care.

Once attached, the tick starts to feed. Before feeding, the tick is flat, like a pancake with legs. After feeding, the tick inflates (engorges) to the shape of a fat grain of rice. What's important here is that if the tick is not yet engorged, it is less likely that you've been infected than if it's fully engorged. Either way, you should document what you see, so that later the doctor has as many clues as possible.

Tick Removal
If you have a camera capable of taking a detailed picture of an attached tick and any details of the wound, rash, etcetera, that might be a good way of documenting in case medical attention is later indicated. It would be a great idea to write down as much information as possible regarding the location and time where the tick was picked up, or noticed, and any observations of the tick, wound, rash, or etcetera. Right in my daily journal, for example, I'll write "I picked a dark, ¼" partially engorged tick off my right shoulder this afternoon."

What Not to do
or Bad Folk Remedies
Studies have shown that asphyxiating a tick by coating it with petroleum jelly, alcohol, or fingernail polish does not cause the tick to detach. Therefore, these folk remedies are not recommended.

Heating the tick, (with a lit match or cigarette, for example) is not recommended since the tick may inject more saliva or regurgitate its gut contents into the patient, thereby increasing the chance of catching the tick vectored disease.

What to do
It is recommended that tweezers or forceps be used to grasp the head, and then to pull gently and slowly to allow the tick to detatch and back out on its own. This way, tick mouth parts are less likely to break off inside the patient. It is not necessary or useful to twist the tick while pulling. The grip should be on the head, not the body, since squeezing the body may cause regurgitation into the wound.

Save the Tick?
The tick itself is not usually of much use to the doctor, but it can be saved in a bottle or stuck between two layers of adhesive tape. It might help, especially if you have had a significant reaction. Some labs can check live and dead ticks for Borrelia, Babesia, Ehrlichia, and perhaps other tick borne diseases. Usually I just drop them and walk away. If you are in camp, you could put the tick on a rock or bark chunk and throw it far enough that it can't walk back to you.

Kill the Tick?
Don't smash the tick, as the infectious content of its guts may then rub into your open wounds, get in your food or eyes, or etcetera. Or you may breath any blood that sprays (aerosols), which is a known way of contracting some tick borne diseases. There are zillions of ticks out there anyway, so killing one won't make much difference.

Other Tick Control Measures
Tightly woven long sleeve shirts, long pants tucked into socks, and etcetera can keep ticks from biting. Most ticks are dark in color, so they will be quite visible on light colored clothes, and can be picked off easily. Permethrin® kills ticks on contact and can be sprayed on clothing. The repellant DEET (N,N-Diethyl-meta-toluamide) is less effective but perhaps better than nothing.

Lyme Disease / Lyme Borreliosis
In the northern hemisphere, Lyme Disease is the most prevalent Tick Vectored Disease. In the United States, Lyme is most prevalent in New England. In the US overall in 2005, 7.9 cases per 100,000 people per year occurred. However, in the 10 worst states, the ratio was 31.6 per 100,000.

It is a zoonosis, meaning it is transmitted to people from a pool of disease in rodents (often White Footed Mice) and White Tail Deer via ticks, mostly hard body Ixodes ticks. Even so, tick and disease transmission density are not direct functions of host density. Though it was once thought that transmission could only happen in the presence of White Tail Deer Odocoileus virgineanus, research shows this is not so.

Larval Ixodes ticks are often not infected. At the Nymph stage, the ticks are still very small, and even though they may attach and feed for a long time, they may escape notice. For this reason, it is thought that most Lyme infections come from Nymphal Ixodes ticks. Adult ticks, too, may escape notice if, for example, prolonged severe weather makes regular tick checks difficult. It is thought that transmission of pathogens does not usually happen until the tick has been attached more than a day. That is why once or twice a day tick checks are so effective in preventing infections.

Symptoms may include fever, headache, fatigue, and an expanding donut shaped skin rash (erythema chronicum migrans, EM). The rash is not always obvious, and the other symptoms are much like other diseases. Sometimes the area around the bite is darker red and the skin is thicker and stiffer.

The disease incubates typically for a week or two before symptoms appear. However, they may show in just a few days and they may delay for months or years after the bite

Untreated Lyme Disease may eventually affect the joints, heart, eyes, and central nervous system. The knees, in particular, can be affected by Lyme arthritis, but ankles, elbows, wrists, hips, and shoulders may also hurt. Neurological issues or neuroborreliosis may include: Facial Palsy (loss of muscle tone in the face), Menigitis (bad headaches, neck stiffness, light sensitivity), Radiculoneuritis (shooting pain and odd skin sensations), Encephalitis (memory loss, poor sleep, mood changes, fatigue), and Permanent Paraplegia.

It is therefore important to record all tick encounters and inform the diagnosing physician to ensure proper diagnosis and treatment.

After Lyme Disease has been eliminated by antibiotics, symptoms of muscles and joints aching, pain, fatigue, sleep problems may continue for months.

Lyme Vaccines
LYMErix® was taken off the market due to reported side effects. Additional vaccines for people are under development. Several vaccines for dogs are available.

Tularemia
F. tularensis tularensis (Type A) is hosted in lagomorphs (rabbits, hares, and pikas) and is quite virulent in humans. Less virulent in people is F. tularensis palaearctica (Type B) (aquatic rodents: beavers, muskrats). Deer Flies Chrysops discalis, Ticks, and some other arthropods vector the disease, and hunters cleaning rabbits contract it by inhaling blood spray or by blood entering wounds.

Tularemia incubates 1-14 days, with most human infections showing symptoms after 3-5 days. Fever may be moderate to high. Lymph nodes may enlarge or suppurate; Fevers are high if lymph nodes are involved. Other symptoms include lethargy, anorexia, and signs of septicemia.

There is an attenuated, live vaccine, but is is only given to very high risk groups.

Tularemia has been used in germ warfare because it is easy to aerosolize, and highly infectious.

Relapsing Fever
After incubating 5-15 days, fevers, chills, headaches, muscle and joint aches, rash, and nausea may occur. The symptoms may last 2-9 days, disappear, and relapse later. 1-2 relapses are typical for the most common US pathogen, Borrelia hermsii.

Along with Ticks, Body Lice Pediculus humanus can vector Relapsing Fever (Pathogen Borrelia recurrentis). This is less common in the United States.

Rocky Mountain Spotted Fever
In the US, about 800 cases of Rocky Mountain Spotted Fever occur each year. It is more lethal and more frequently reported than other rickettsial diseases. The disease incubates as long as one to two weeks before symptoms arrive. Often, the tick was not noticed and is gone before symptoms arrive. The symptoms include fever, headache, muscle pain, and sometimes a noticeable rash. Clearly, these symptoms are similar to those of many other problems, so being able to tell the doctor about a tick bite is very important. It occurs mostly in the southeastern US, but at lower rates throughout the Americas. Only a few percent of the tick population, even in problem areas, carries the pathogen, Rickettsia rickettsii. Untreated, RMSF can progress to involve the respiratory, central nervous, gastrointestinal, and renal systems. Long term problems may include partial paralysis, gangrene leading to amputation of fingers, toes, arms or legs, hearing loss, loss of bowel or bladder control. Clearly, it is very important to be diagnosed correctly and treated as early as is possible. It is very important observe and record every tick bite, to tell the doctor for correct diagnosis.

Q Fever
Q Fever incubates 9-40 days. Fever, malaise, sweating, severe headache, muscle and joint pain, appetite loss, respiratory problems, dry coughs, plueritic pain, chills, confusion, nausea, vomiting, and diarrhea may last 7-14 days.

Later, pneumonia, hepatitis, and heart problems may develop.

An inactivated whole cell vaccine, Q-Vax®, has been developed. Vaccinating exposed persons can cause severe reactions.

Along with ticks, Q Fever can be transmitted from cattle, sheep, goats, cats, and dogs by inhaling aerosols or by contact with body fluids.

Q Fever has been weaponized because it is easily aerosized, and just one inhaled cell can infect humans.

Ehrlichiosis
After incubating 2 weeks, Ehrlichiosis may cause high fever, severe joint and muscle aches, vomiting, headache, and fatigue.

Babesiosis
Babesiosis usually is asymptomatic, but mild fevers and diarrhea sometimes occur. In more severe cases, symptoms might include 105°F fever, shaking chills, severe hemolytic anemia, and respiratory distress. Although most cases resolve without treatment, drug therapies are available.

Colorado Tick Fever
Colorado Tick Fever is a viral disease. It usually is found mountains at altitudes from 4,000 to 10,000 feet. Typically, infections occur from March through September, peaking in June.

After incubating 3-20 days, symptoms may include fever, chills, headaches, pain behind the eyes, light sensitivity, muscle pain, malaise, abdominal pain, nausea, and vomiting, and rash. Symptoms may be present for a few days, resolve, and return for a few more days. After 4 months, the virus is probably gone.

Tick Borne Encephalitis
Tick Borne Encephalitis can also include meningitis and fever. In 10-20% of patients, long lasting neuropsychiatric problems occur. There is no cure. Hospitalization may be require to minimize brain damage as the disease runs its course. A vaccine is available.

Tick Paralysis
Tick Paralysis is caused by a neurotoxin produced by the tick. No separate pathogen is involved.

In North America cases occur between April and June, when adult Dermacentor ticks are active. Tick Paralysis occurs when an adult female tick, fully engorged and with eggs (gravid), produces the toxin in her saliva, and delivers it to the host during feeding. Peak toxin delivery usually occurs the fifth to seventh day after attachment. Symptom onset or severity may coincide with this peak in toxin delivery. Symptoms may begin with weakness progressing to paralysis in the legs. The paralysis ascends to the trunks, arms, and head in hours. Tick paralysis is fatal in 10-12% of cases, typically due to respiratory paralysis.

Removal of the tick stops delivery of the toxin, and symptoms usually resolve within hours.

No Vaccine is available.

Pajaroello Tick Bite
Symptoms vary from red bumps with no pain or itch lasting a few weeks, to rare cases with severe swelling and pain. Tissue necrosis and ulceration may occur, with healing being prolonged. These severe reactions may be due to sensitization from previous bites. The tick injects no known venom or toxin; all effects are caused by the body's response to the tick's saliva.

General Comments on Tick Borne Diseases
Unfortunately, the early symptoms of Tick Borne Diseases often don't indicate that a serious problem has started. Hikers, for example, get plenty of rashes that come to nothing. And many other symptoms don't seem worse than might be caused by minor flu or allergy bouts.

Later, when more serious symptoms develop, details of tick encounters may be long forgotten. So I encourage hikers to take notes. Perhaps in your regular journal, a note that you removed a tick from your leg on July 2nd might come in very handy when speaking with a doctor. It might nail down exactly what valley you were in, which might tell the doctor which disease is likely. The diseases usually progress to a certain state in a certain number of days, so this too will help the physician diagnose which disease it is. If there is a distinctive looking rash, a photograph would help.

How Ticks Transfer Disease
How Ticks Become Infected
A female adult tick may receive pathogens from a male with the sperm during mating. A tick egg may be infected with a pathogen from the mother. So it is entirely possible that a newly hatched larva is infected as it seeks its first meal. Each blood meal is another chance for a tick to acquire pathogens. It is entirely possible for one tick to be infected with more than one disease, and pass them onto you with one bite.

How Tick Larvae Feed on Hikers
An adult female tick, after feeding and engorging, detaches from her host, drops to the ground, and lays her eggs. Where there is a deer bed, or an isolated water source, deer and other mammals linger, meaning more eggs will be laid in that area than elsewhere. The eggs hatch and larvae crawl out, looking for a meal. A deer, hiker, mouse, etcetera is sleeping there, and it's easy for the tiny larva to crawl right onto the skin and start feeding. The wise hiker does not sleep where other mammals hang out!

Each Tick Feeds on Multiple Hosts in Sequence
Ticks attach to hosts to take blood meals at least several times in their lives. Ticks eat nothing but blood, and absolutely require a blood meal to progress from one development stage to another. Additional attachments and meals may be required if the tick detaches before acquiring sufficient blood to metamorphose or to produce additional sets of eggs. After hatching from their egg, they are in a larval stage and must take one blood meal to metamorphose to the nymph stage. The nymphs must feed again, in some species multiple times, to change into adults. Adult females must feed each time they breed. Each time a blood meal is taken, the tick may pick up a new pathogen. And it may transmit any pathogens it is already infected with. Yuck! Don't rest where other mammals live!

How Ticks Feed On and Infect You
Ticks are Telmophagic Feeders, meaning they penetrate your skin at a random place then dissolve / lyse your flesh until a capillary breeches and blood flows. They use cheliceral digits to cut through the skin, and barbed hypostomes to attach. Ixodids also use cement to strengthen the attachment, as they may need to feed for weeks at a time, but Argasids feed much more quickly and don't need the cement. Ticks inject saliva containing histiolytic secretions that liquefy tissues, which are consumed. Eventually, a capillary is breeched and blood can be consumed. To prevent clotting, the saliva contains apyrase. Prostaglandin and Prostacyclin prevent vasoconstriction. The saliva may also contain any infectious agents. Some Argasids excrete wastes with the saliva. With Tick Paralysis, the responsible neurotoxins are included with the saliva.

If you cause ticks to regurgitate their digestive tract contents by burning them or by squeezing the body during removal, you are injecting your own blood and any left from previous hosts, plus digestive juices, plus more pathogens. Thus, you are greatly increasing your chance of being infected. Be careful not to inject additional disease pathogens as you remove a tick!

General Tick Information
Ticks are external parasites, or ectoparasites and feed solely on blood (hematophagy).

Body Structure
Adult ticks have 2 body segments, an anterior capitulum / gnathosoma or head / mouth and body or posterior idiosoma containing the legs, digestive tract, and reproductive organs. Larvae have 6 legs, whereas nymphs and adults have 8.

Life Cycle
Ixodid and Argasid ticks grow from eggs through larval, nymphal, and adult stages of development.

Ixodids have a blood meal each at the larval, nymphal, and adult / breeding stages. The cycle takes at least 2 months and sometimes several years. Females can mate several times, but each mating event kills the male. Females lay up to thousands of eggs on the ground after a blood meal, then die. Males feed less, and engorge to a smaller size, as they do not require nutrients to produce eggs. Ixodids can tolerate cold, submergence in water, and high humidity.

Argasids require at least one blood meal at several nymphal stages. The adult female can feed, drop off, lay eggs, and reattach to repeat the cycle several times before dying. They are better adapted to dry conditions than Hard Ticks / Ixodids.

Next: Water Borne Disease

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