Lyme Disease

Ticks & Other Vectors of Lyme & Other Diseases

By Eva Haughie Pres, Empire State Lyme Disease Association

<< Back

DISEASE TRANSMISSION WITH ONE BITE
A tick, mosquito, louse, mite, arachnid, or other vector can be infected with microbes, worms or parasites. If these parasites are transmitted via a bite or other means, it could potentially cause considerable health challenges to humans, livestock and pets. A single tick can harbor multiple different disease-causing organisms and can transmit all of them in just one bite! It is hard not to feel alarmed when one considers this information. However, it is good to be informed, educated and aware, to know how to avoid bites and what to do if bitten. You must draw your own conclusions about whether a bite is something to worry about, but to be on the safe side, note a bite and any consequences on a calendar or in a journal. Fortunately, there is no need to panic because there are many ways to prevent bites, many ways to attend to the consequences of any bite and we are learning more each day. If a person is sick and suspects tick-borne illnesses, but no bite has ever been seen at least, in some endemic areas, doctors test patients by doing a "tick panel" which includes looking for the most common tick-borne diseases in that area. Tests are yet to be highly accurate or reliable, so a clinical evaluation where a diagnosis relies on other factors of the patient's history rather than solely on results of blood work.

With regard to all flying and crawling vectors, Evergreen Equine of Vermont puts it plan and simple, "External parasites can be just yucky, annoying, or downright dangerous." Evergreen's list of potential disease-carrying parasites includes house flies, "friendly" flies, stable flies, horse flies, deer flies, bot flies, mosquitoes, culicoides, lice and ticks. West Nile Virus, Eastern equine enchepilitis, and malaria are a few of the many diseases mosquitoes carry. On Long Island, our Vector Control programs keep mosquito populations down which may be why there are so few cases of mosquito-borne diseases here.

Several years ago, the Nassau County Health Department's Lyme brochures reported that deer flies, horse flies and mosquitoes could also possibly transmit Lyme disease. Their brochures may have referred to a 1990 article in the New England Journal of Medicine which stated that deer and horse flies were suspected of transmitting Lyme disease. According to the current Ohio State University Extension Fact Sheet, these flies are also potential vectors of such diseases as anthrax, tularemia, anaplasmosis, hog cholera, equine infectious anemia, and Filariasis (worms).

Deer ticks may carry Lyme disease and fleas carry plague, but according to the Britannica, "Ticks around the world surpass all other vectors except mosquitoes in the number of diseases they transmit to humans." A Swedish study revealed that migratory birds can transport ticks thousands of miles, possibly introducing the specific diseases they carry into new regions.

So generally: avoid all vectors but if you are bitten, then be careful to note any rash or symptoms of illness which may follow the bite and seek medical attention if illness follows after the bite.

OTHER POSSIBLE MODES OF TRANSMISSION OF TICK-BORNE DISEASES
The most well known of tick-borne infections, Lyme disease, is sparked by the transmission of a spirochete called Borrelia burgdorferi. Since Lyme disease is similar to Syphilis, a disease not known to be vector-borne, but sexually transmitted, there has been a concern about other modes of transmission for Lyme disease besides a tick bite. Studies on human transmission from an undiagnosed, infected mother across the placenta to the fetus have been done; but while some report that there is a definite risk, other studies reassure us that there is little or no risk. It is perhaps worth repeating these studies. It is a topic for women of child bearing age who live in endemic areas and may have had Lyme disease. Some also believe that, like Syphilis, human sexual transmission of Borrelia can occur, especially from the male to the female. In addition, since Borrelia spirochetes have been found in breast milk, there is a concern that breastfeeding could transmit the disease. There is concern of vector-borne diseases being found in our blood supply. Clinical Microbiology Reviews, January 2011 states that Babesia is increasingly being transmitted by blood transfusion: estimates suggest that between 70 and 100 cases of transfusion-transmitted Babesia (TTB) have occurred over the last 30 years.

TICK-BORNE DISEASES
One Internet site states there are at least forty known tick diseases. It is important to know this for if multiple infections are present, it can further complicate a diagnosis and subsequent treatment. It is difficult to compile a complete list of all possible tick-borne diseases: first because people travel extensively and can contract a disease specific to a region they visited; second according to the Swedish study, birds can transport ticks over a wide range; third, some diseases are new and emerging while others may not have been discovered or realized yet.

The following are diseases that animal and humans may contract from ticks. Some are more common to the Northeast and others are more common in other regions.

The Lyme borreliosis group: includes Borrelia (B.) burgdorferi, B. afzelii, B. garinii, caused by Gram negative spirochetal bacteria from the genus Borrelia. Although it has been stated that there are 300 strains of Borrelia, with 100 found in the US, another report states that there are at least 37 known species, 12 of which are Lyme related, but it also states there are an unknown number of genomic strains and several other species not associated with human disease.

The Tick-borne relapsing fever group includes several species, such as B. hermsii in the Nearctic ecologic region and B. persica in the Palearctic, that cause endemic relapsing fever in humans

Besides the spirochete Borrelia burgdorferi, other pathogenic organisms found in ticks are protozoa: the protozoa Babesia microti, other protozoa such as Babesia duncani and Cytauxzoonosis.

Some Rickettia found in ticks include Ehrlichia chaffeensis, Ehrlichia ewingii, Anaplasma phagoÂcytophilum, and Rickettsia rickettsii (Rocky Mountain Spotted Fever).

Some Bartonella organisms ticks can carry and transmit are Bartonella henselae and Bartonella Quintana.

Other disease organisms important for the havoc they can wreak are Coxiella burnetii, Southern tick-associated rash illness (STARI), Francisella tularensis (Tularemia), Mycoplasma fermentans and other Mycoplasma species.

Ticks may also carry viruses such as HHV-6, XMRV, Powassan encephalitis and other arboviruses, Deer Tick Virus, various forms of typhus, Q fever, and Colorado tick fever.

A fairly new addition to this (incomplete) list is the mystifying Morgellon's disease. While there are already several fine foundations dedicated to support and education for Morgellon's victims, the CDC is also supposed to be conducting an epidemiologic investigation to learn more about this condition.

Not from an organism, but from a toxin, Tick paralysis can also be contracted from a tick bite.

Finally, filaria, nematodes, microfilaria (worm parasites) are also found in ticks and therefore may also be transmitted with a bite.

These are some that are known today; in reality, the list may be much longer.

TICKS
The tick, a cousin of the spider, is an eight-legged arachnid with forearm hooks that snag the fur or fabric of a passing target. It has a pair of cutting mouth parts with a serrated tube that serves both as an anchor and a drinking straw. There are two known families of ticks, inclusive of about 840 known tick species. One tick family includes those with leathery hard bodies like the dog and deer tick. To enable metamorphosis, they take only one big meal during of their three life stages. The second family is the soft bodied ticks which are more like fleas; they feed repeatedly and often. Not picky in their eating habits, ticks take their requisite blood meals from all mammals, reptiles, and birds, with the exception of fish.

TICK ATTACHMENT FOR HOW MANY HOURS?
How does the duration of tick attachment impact on a person or pet contracting a disease? Much is said about the length of time a tick is attached and feeding in order to transmit disease because in a typical scenario, the disease organisms reside in the tick's midgut and have to travel to the mouth after the tick bites which takes some time. It may be important to consider that for transmission of disease and for a subsequent diagnosis, the "requirement" that a tick be attached for 24, 48 or 72 hours cannot really be met. First of all, people remove ticks as soon as they see them; so while they can usually state the time they removed the tick; they may not as easily state the time the tick was first attached! Indeed, not only will a person be unable to ascertain the hours a tick was embedded, often enough, people never even see a tick or rash.

According to North Carolina State University Department of Entomology, "Frequent self-inspection lessens the chance of a tick having enough time to attach. A tick must be attached at least six hours in order to transmit disease organisms causing Rocky Mountain spotted fever; therefore, the longer a tick is attached, the greater the chances are that germs will be transmitted. The minimum attachment time required for transmission of Lyme disease spirochetes is not yet known."

Pronouncements about tick attachment time and transmission of disease have been garnered from early scientific studies, the majority of which used a baseline low of 24 attachment hours. As these studies use lab animals and not human subjects, questions also arise as to whether these studies are helpful since mice or other lab animals' response to tick-borne disease are different from a human response. While these studies may show only a few (rare or uncommon) cases of mouse infection at 24 hours, in reality there are no results for less than 24 hours of tick attachment. It is possible then, that the few mice who fall into the 24 hour range could have been infected at a duration of less than 24 hours. Perhaps the demand or stipulation for a tick attachment time of 24 or 48 or 72 hours should not be used as a rule to determine if a human has contracted a tick borne disease.

Indeed, tick-borne pathogen transmission to a host could be very rapid if the tick is systemically infected with microbes. They will be dispersed throughout the tick's body and found in the tick's mouth. Additionally if a person is the tick's second host after dropping off a first host, pathogens may be in the tick's mouth having already traveled up from the midgut during the first feeding.

Be careful! Another factor in an unfortunate quick disease transmission time is that no matter how long the tick is attached, it can regurgitate bacteria into the bite site if squeezed with removal. So, be careful when handling potentially infected ticks, such as when removing ticks from a pet. Infective body fluids from the tick may get into a wound or mucus membrane. (See below for proper tick removal.)

YOU FIND A TICK, NOW WHAT IS IT?
Places that offer to evaluate ticks found embedded on people or pets are health departments, colleges, universities, and private or commercial laboratories. Depending on their resources, these tick services may be current or discontinued so it is best to telephone for availability, instructions and to determine the fee, if any. Some labs will test the tick for the disease organisms it carries, while for instance, health departments may only evaluate the tick for suspected attachment time and/or for the type of tick and the stage of its life cycle.

A patient found a tick crawling on him but he believed it had not bitten him, had not been embedded, and it had not appeared to be engorged. To be on the safe side, he sent it to the NYS Health Department where they determined it to be a deer tick that had been feeding for 48 hours. This illustrates how difficult it can be to identify a tick to try to determine if the tick has transmitted any infection. Across the spectrum of species, unfed tick larva are tiny, some the size of a poppy seed, nymphs are a bit bigger, the adult male is the third largest in size and the adult female is the largest. When engorged from feeding, their sizes usually appear to increase considerably.

See examples here!

In the east, commonly found ticks are the Deer Tick, (Ixodes scapularis), line one in the photo above, the American Dog Tick (Dermacentor variabilis) on the second line, the Lone Star Tick (Amblyomma americanum) on the third line and on the fourth, the brown dog tick (Rhipicephalus sanguineus); the Wood Tick (Dermacentor andersoni) is less common, (not shown) and in the west, one encounters the Western Black-legged and Rocky Mountain Wood Ticks.

People ask why deer and wild animals do not get sick with the same illnesses that ticks give to humans, livestock and pets. While studies show that some animals have certain degrees of immunity, there are reports that other animals in the wild are suffering from tick encounters. Wildlife, we see, is not immune: for instance, moose have been discovered with as many as 400,000 ticks feeding on them, losing all their hair as they rub hopelessly against trees.

© copyright January-2011 by Eva Haughie

TEN QUICK TIPS

• Lyme disease is worldwide & rampant in NYS.
• A tick bite can transmit tick-borne diseases so note and record dates, any symptoms, save the tick, photograph any rash; i.e. Keep a record!
• Symptoms may occur soon or months after bite.
• Rashes may be seen soon, months later or may not be seen at all.
• Early diagnosis is better than later diagnosis.
• Tick-borne diseases can be very complicated.
• Co infections can complicate diagnoses & treatments.
• Misdiagnosis with an autoimmune disease or being told you are fine results in late diagnosis.
• Due to inaccurate blood testing, diagnosis cannot solely depend on test results.
• Symptoms risk factors, etc, help in a "clinical" diagnosis.
• 1 Prevention Ð DEET, Permethrin
• See websitewww.EmpireStateLymeDiseaseAssociation.org

HOW TO REMOVE A TICK

1. Do not squeeze or twist the body of tick or burn it or use any substance on it.
2. Grasp the tick close to the skin with tweezers and pull it straight out.
3. Use antiseptic on skin, wash hands and disinfect tweezers.
4. Record the date and any symptoms that may follow & see a physician familiar with tick-borne diseases

References:

1. www.EmpireStateLymeDiseaseAssociation.org
2. Typing of Borrelia Relapsing Fever Group Strains Jonas Bunikis, Jean Tsao, Ulf Garpmo, Johan Berglund, Durland Fish, Alan Barbour, Aug 10, 2004, Typing of Borrelia Strains | CDC EID
3. http://en.wikipedia.org/wiki/Lyme_disease_microbiology
4. http://www.evergreenequinevt.com/externalparasites.html
5. http://ohioline.osu.edu/hyg-fact/2000/2115.html
6. New England Journal of Medicine 322:1752, 1990
7. Clinical Microbiology Reviews, January 2011, p. 14-28, Vol. 24, No. 1 0893-8512/11/$12.00+0 doi:10.1128/CMR.00022-10 Transfusion-Transmitted Babesia spp.: Bull's-Eye on Babesia microti
8. http://www.ces.ncsu.edu/depts/ent/notes/Urban/ticks.htm
9. http://www.tickencounter.org/education/tick_identification
10. Dr. Stephen K. Wikel, University of Connecticut Health Center
11. Jose M. C. Ribeiro, National Institutes of Health in Bethesda, Md.
12. Dr. James E. Keirans, curator of the Smithsonian Institution's National Tick Collection, at Georgia Southern Univ in Statesboro, Ga.
13. Dr. Daniel E. Sonenshine, Old Dominion University in Norfolk, Va., "Biology of Ticks" (Oxford University Press, 1991 and 1993)
14. http://www.lovelycitizen.com/story/1647911.html
15. Britannica Encyclopedia

© copyright January-2011 by Eva Haughie