Lyme Disease Ticks Me Off

Biology 103
2000 First Web Report
On Serendip

Lyme Disease Ticks Me Off

Jeanne Braha

Ticks have gotten a bad rap for a long time. Humans' initial impressions are bound to be negative, due to our tendency to clump all those little critters that scurry around with their exoskeletons and multiple legs into one big category of "get that thing off of me!" To compound the situation even further, Ixodes scapularis (the black-legged or deer tick) has been maligned as the cause of Lyme disease throughout the northeastern United States. (1). A veritable war has been declared on the little scamps: before taking off on a hike, people douse themselves with a variety of tick-killing chemicals; cover their extremities in light colored clothes to more easily spot the ticks and make mental notes to mow down the vegetation creeping up on their yards at home. Is it possible to take adequate precautions against Lyme disease while still maintaining something that resembles a regular lifestyle?

I. scapularis (also referred to as I. dammini) does not do much to enhance its reputation by feeding, in part, on human blood. But are these arthropods the sole cause of Lyme disease? No. They are simply the vector for Borrelia burgdorferi, the bacterium that is transmitted at these mealtimes and is the actual catalyst for the human reactions classified as the clinical illness Lyme disease. (6). To prevent contraction of Lyme disease, it is necessary that we take a closer look at how the disease gets to us. In this way, we can take appropriate actions to deter the little critters.

B. burgdorferi is a corkscrew-shaped, non pus-producing bacterium. It is commonly referred to as a spirochete because of its shape. The strain that infects humans in the United States is B. burgdorferi, sensu stricto. There are two other strains that have been identified, but they are dominant only in Europe. (6).

The bacterium takes a strange path through the tick's midgut via at least one vertebrate. I. scapularis has three stages (nymph, larva and adult) in its life cycle over a two-year period. In each of the stages, the tick crawls from the tip of a blade of grass or the leaf of a short bush onto the host. Ticks cannot jump or fly; they do not drop onto the heads of hosts from overhanging tree branches (so we definitely can rule out razing our forests as a preventative measure). Once on the animal, it spends a few days with its mouthparts under the host's skin, taking in a leisurely meal of blood. Once satiated, the tick then drops off and molts into the next stage. Adult females drop off deer in early spring or summer of their second year to lay eggs, and then die. The eggs hatch in the summer and ticks emerge in larval form. (1). These larvae tend to feed on smaller mammals, such as white-footed mice, through the summer and early fall. Over the winter they are relatively inactive, then molt into nymphs in the spring. The nymphs feed on small mammals or birds during the spring and summer. In the fall, they molt into adults and feed on larger mammals, especially the white-tailed deer, until the following spring, when the cycle is renewed.

As they feed, ticks can transmit B. burgdorferi to the animal serving as their meal, or acquire the spirochete from such an organism. The ticks need to be attached to their host for a minimum of 24 hours(1). (some sources say two full days) (6). to transmit the bacteria through salivation or regurgitation. A great amount of saliva is secreted during feeding, so this is generally considered to be the main means of transmission to the host. An additional method of giving the bacteria to the host is if the animal grooms itself and crushes the tick in the process, thereby exchanging fluids with the critter. This is a concern for folks removing ticks found attached to themselves - if improperly removed, they can inadvertently crush the tick's body. (4). Also, a very small number of ticks are born carrying the bacteria if their mother carried it as well.

The tick can be infected with the Lyme-causing bacteria at any stage in its life and can feed on humans at any stage. The animals suggested above are simply the most common. However, the bacteria are transmitted to humans most frequently during the nymphal stage. (1). Nymphs are most active in the spring and summer, making that the time to play it extra safe. The pattern of transmission is not exclusively because more nymphs than ticks in other stages feed on humans. A number of other factors come into play: the nymphs are harder to spot and remove than adults; and nymphs are more active in warmer months, when exposure to tick habitat is greater for humans. Even a fully-fed (and thus larger) adult can be small to spot on one's skin. They almost look like freckles or moles. A close inspection reveals that the "freckle" is in a strange position - pointing outwards instead of lying flat on the skin. It is theoretically possible to contract Lyme disease through blood transfusions or coming into contact with infected blood or urine. However, the United States Center for Disease Control (CDC) has found no solid evidence of such an event.

Once infected with B. burgdorferi, most humans exhibit an erythema migrans (EM), more commonly known as the bull's eye rash. This occurs at the site of the bite, but secondary EMs might appear elsewhere after a brief incubation period. Ticks seem to prefer to crawl up humans to dark, moist areas such as the groin, armpits, and trunk. The incubation period, the time from the bacteria's entrance into the body until symptoms such as EM appear, can be anywhere from three to thirty days. One to two weeks is a more common timeframe for the bacteria to spread throughout the body via the bloodstream, the lymphatic system and via the skin. Initial symptoms other than the rash usually are quite similar to those of the flu. This can lead to many missed diagnoses. The cautious flu victim in the middle of the summer should review her outdoors activity and be sure to mention it to her physician.

Later symptoms of untreated Lyme disease include arthritis, neurological irregularities, especially facial nerve palsy, some cognitive disorders and, very rarely, cardiac abnormalities. Lyme disease does not usually result in death. The most common late-stage symptoms for B. burgdorferi, sensu stricto are musculoskeletal manifestations, such as arthritis and inflamed joints. European strains are more commonly associated with neurological and cutaneous expressions. (1).

Treatment of Lyme disease with antibiotics has been largely successful. Recovery is fairly quick and most late-stage symptoms are avoided. There is currently a great debate about treatment of the disease amongst health care professionals and individuals who have had Lyme disease. (3). However, the overwhelming advice at this point seems to be to take the antibiotics as prescribed by a physician.

A recent addition to the conversation is the Lymerix(r) vaccine, which is administered to humans to prevent contraction of Lyme disease. It seems to excite antibodies to kill the spirochetes in the tick's midgut, before they are transmitted to the vaccinated human. (1). This suggests that a vaccination of one person might then prevent Lyme disease for another person: the tick's supply of the bacteria is eliminated when it moves on to the next host. If it is a larva or nymph, it is now incapable of transmitting the spirochetes to another animal in any further feedings. The CDC is currently recommending the vaccine only after an evaluation of the risk for the individual. (1).
Presumably, it is wise to use a new vaccination only if the risk of contracting Lyme disease is very high for the same reasons we take similar precautions with all other medications - it is always most prudent to wait until many clinical trials are available to attest to the safety of the vaccine.

In general, the necessary course of action is to carefully inspect your body, especially the preferred attachment areas of black-legged ticks, for any critters trying to use you for a meal. A full day is required for enough saliva to be exchanged for transmission to occur - ticks are much slower feeders than humans. This gives the cautious outdoorsperson plenty of time to find and remove (carefully, of course) the offending arthropod. Simply grasp the mouthparts firmly with a pair of tweezers and pull away from the skin. The bacteria are in the midgut, so you don't want to break that open. Once the tick is removed, wipe the bitten area with an antiseptic as a general precaution against infection. (4). If the mouthparts remain embedded in the skin, Lyme disease can not be transmitted because they do not hold any of the spirochetes. However, infection is a concern in this case, and a physician should be consulted.

So do we need to spend our summers inside air-conditioned buildings sealed off from the outside world? All the information available suggests that it is safe to venture outdoors, even in the temperate, humid climates favored by ticks. Just remember to take precautions (all the advice mentioned above is mine only; it should not be used as medical advice) when heading into areas frequented by deer ticks and be sure to check for any feasting friends upon your return. Don't be afraid to ask questions of your doctor. Proper and relatively quick diagnosis of the disease is key, so advocate for yourself. The above information is a good general overview of Lyme disease. However, since your personal health is the issue, you should investigate further before deciding on your personal course of action.

WWW Sources

1)CDC Division of Vector-Borne Infectious Disease - Lyme Disease, This was the most comprehensive site I found, with plenty of great photos and factual information.

2)Lymetruth , Website and newsletter for and by survivors of Lyme disease.

3)Tick - Brittanica.com

4)Tick Biology

5)Tick Removal Tools

6)Tick Research Laboratory, Fantastic visuals (even movies!) of ticks, mouthparts, etc. close up!

 

 

Comments made prior to 2007

Hello...first before I get into this...Thank You for writing a story on Lyme Disease...they only problem my friend is this is not all accuarate...maybe this is an old article....I got Lyme in 1992....and think I had it way before then...You cannot go by what the CDC says....some reason they do not have their facts straight....Possibly you need to get on some of the Lyme forums and see what people say that have been mis-diagnoised...like myself for years...that a simple course of antibiotics would of saved us all YEARS and YEARS of heartache....

There is NO vaccine for lyme...only for dogs...they tried to get one for humans and it did more damage than good....

Ticks do fall out of trees....and they do not have to be on you for the 24 hours as this says...a person can touch a tick and get the siliva on them, a person can eat meat that has been infected and get Lyme...I did have a head broken off into me and I was dragging my butt until I had it dug out of me at the emergency...and Yes I did get LYME and Lord knows what else..but the TEST ARE NOT ACCURATE! And I was told it was not in the county I lived in...so un-true...there are tons of co-infections also that you can get....

Ticks are NOT the only way you can get lyme Disease...anything with a mouth part that can inject into us is going to spread this disease...birds carry it...mice...so that means allllll rodents....cows...deer....It is under the microscope that humans are able to pass this on to other humans through contact...sex and giving birth...there is also the possiblity that people are spreading it through eatting off the same utensils...kissing...this bacteria is I was told a cousin to syphillis....they are both cork screwed bacterias...and imbedded in every tissue...Organ...blood stream....yes it can be transmitted through blood transfusions....

This disease and the doctors turnig their heads and pummping me up full of other medications instead of a simple course of antibiotics really put a damper in my life for 16 or more years...I still have some mental issues I am dealing with....But this is not only about me...there are Hundred of thousands if not millions ...well I don't know the numbers but sooooo many people that have this disease that are in mental institutions...wheel chairs...told they have ADD...told that they have M.S. ...Alsheirmer...and so many more....it ruins marriages ...people lose their friends...their families...their jobs.....ahhh...it is one Nasty Disease!!!!

Also the Bulls Eye rash NOT VERY MANY PEOPLE GET THAT! So it can not be used as a full proof symptom for getting Lyme either...And it also can be so different in every body....

Thank You for your time....please maybe revise your article...so happy that you took the time to post imformation...but it does need to be updated...to many people would read it and say...oh well that is a hard Disease to get....and it is soooo easy....they say that it could be easier than Aids to get now ... Jodie, 29 July 2006