BUG WEEK: Day 7.5- I forgot about tick-borne encephalitis

After 3 hours of lecture today on meningitis, meningoencephalitis, and encephalitis, I became aware of an omission on one of my posts. On 7/15 I listed the diseases carried by the Ixodes tick (AKA black-legged tick AKA deer tick), but I left out a strain of Flavivirus, which can cause tick-borne encephalitis. The interesting thing about this is that all other viral causes of encephalitis are transmitted by mosquito bites. West Nile virus is also a Flavivirus, and is probably the most commonly known strain in the US. (especially after the New York outbreak a few years ago)

Meningitis is inflammation of the meninges, which is one of the protective tissue layers of the central nervous system (brain and spinal cord). Encephalitis is inflammation of the brain tissue. Meningoencephalitis is both. TBE can present as any of the three. You'll have a patient with a fever, altered mental status, and mosquito or tick bites. They don't necessarily get the stiff neck that people with bacterial meningitis do.

Anyway, there are no skin findings and treatment is supportive, meaning there is no cure, but it is something to think about if you're in tick-infested country. Also, there is a rare association with neurological side effects similar to amyotrophic lateral sclerosis (Lou Gehrig's disease). I couldn't find much research on it, but it does exist in case reports. ALS is a neurodegenerative disorder where the motor neurons in both the central and peripheral nervous systems start to die. It is one of the only neurodegenerative disorders that has both upper and lower motor neuron symptoms.

Müller WK, Hilgenstock F. An uncommon case of amyotrophic lateral sclerosis with isolation of a virus from the CSF. J Neurol. 1975 Dec 2;211(1):11-23.Links

An atypical case of amyotrophic lateral sclerosis (ALS) is described, characterized by early manifestation, a long lasting course with asymmetry of the lesions, absence of bulbar symptoms in the presence of an otherwise very advanced symptomatology, and constant signs of an inflammatory reaction in the CSF which was the reason to initiate extensive virological studies, including procedures for virus isolation. A virus belonging to the TbE complex of arbovirus group B (tick-borne flavivures), was finally isolated from the CSF. About 70% of the ALS cases in Hamburg/W. Germany, examined for antibodies, apparently had contact with this virus. The antibody pattern found made it possible to explain this exceptional case.

I could only find a couple articles written specifically on this topic since 1975. They think that some of the antibodies produced in reaction to the virus end up attacking motor neuron cells.

This concludes BUG WEEK 2007.

BUG WEEK: Day 7- The Brown Recluse

The brown recluse (Loxosceles reclusa)is the last one I wanted to cover before BUG WEEK 2007 ended. Actually, there will probably be another bug week... or maybe just a worm week... or half week (I don't think I could do a full week of worms).

The brown recluse is interesting to me for a couple reasons. The first is that it has a painless bite. The second is that it is in Texas (like me).

As the name implies, the spider is both brown and reclusive. It lives in wood sheds, garages, attics, etc. Basically any place where it can be left alone. We come across them when we decide to clean up these places. It's back is supposed to look like a violin, which it does sometimes. It is found in the midwest and the Gulf of Mexico states (except Florida).

It has skin findings! (sometimes) Most bites are relatively mild and could cause some inflammation, which should be treated with ice packs. If it starts to turn dusky and the wound is not healing, it might be necrotic. This is rare, but serious. The necrotic (dying) tissue can spread and take a while to heal. In some cases, multi system organ failure can occur. Dapsone has been used with mixed results to decrease necrosis.

Elston DM, Miller SD, Young RJ, Eggers J, McGlasson D, Schmidt WH, Bush A. Comparison of colchicine, dapsone, triamcinolone, and diphenhydramine therapy for the treatment of brown recluse spider envenomation: a double-blind, controlled study in a rabbit model.Arch Dermatol. 2005 May;141(5):595-7.

This study basically said that none of the agents helped with necrosis or eschar formation in the rabbits


These bites are very rare and often overdiagnosed. The following conditions should be kept on your differential diagnosis as they present similarly and are far more common:
1. Staph or Strep infections
2. Pyoderma gangrenosum
3. Herpes
4. Diabetic ulcer
5. Squamous cell carcinoma
6. Deep fungal infections
7. Chemical burns
8. Localized vasculitis
9. Sporotrichosis
10. Site of tick bite in Lyme disease

I actually saw a patient with a lesion that could be any one of these things today. Brown recluse bite was not in the top 10 of our differential.

BUG WEEK: Day 6- How to treat head lice

Robinson D, Leo N, Prociv P, Barker SC.Potential role of head lice, Pediculus humanus capitis, as vectors of Rickettsia prowazekii. Parasitol Res. 2003 Jun;90(3):209-11.

Head lice are the same species as body lice and can transmit disease! However, there have been no cases that I could find of an isolated head lice infestation that caused the transmittal of infection. The article above makes the excellent point that when one has a body lice infection, one will also have a head lice infection, so it is difficult to tell which ones are transmitting disease. I suspect that head lice treatment guidelines will continue to be lax as long as there are no elementary school kids who come down with typhus.

Head lice don't live on pets or clothes, and they require human blood to survive. You can see the nits (the eggs that are near the hair root) much easier than you can see the actual louse. So when people do lice checks, they're not actually looking for little bugs running around on your scalp, but they are trying to see little clearish oval eggs attached to your hair.

I've never had lice, but it seems pretty popular with the under-12 crowd. All that hat-sharing, head-to-head contact, and shared nap space makes for the perfect environment for a lice infestation. Judging from a quick Google search, there's big money in the lice-removal market. Combs, medicinal shampoos, and non-chemical treatments are all over the place. But what do the doctors recommend????

Here are the basics of lice removal:
1. treat with an agent that will kill the lice and help loosen the nits
a. pyrethroids- over the counter, permethrin and pyrethin are most common, documented increasing resistance, relatively few side effects
b. lindane- over the counter, documented increasing resistance, associated with some CNS side effects (seizures)
c. malathion- prescription, 98% ovicidal (should only require 1 or 2 treatments), no known serious side effects, flammable (so monitor children after treatment), no known resistance
2. manually remove the nits and lice
3. wash clothes, sheets, and other heads that the infected head may have come in contact with

The American Academy of Pediatricians recommends the use of over the counter pediculicides first (permethrin 1%) and malathion for resistant cases. Also, once treated, patients are safe to return to school, even if they still have nits in their hair. Interestingly enough, the main societal cost associated with lice is the lost school time by the kids and the lost work time by the parents who have to stay home with them. The AAP believes that the "no nit" policy is obsolete and that the treatments are effective enough to prevent outbreak. Also, they think that lice screening and the "no nit" policy are out of proportion to the medical significance of a head lice infestation. The children should, however, be discouraged from head-to-head contact with others.

The National Pediculosis Association disagrees. They are not proponents of pesticidal treatments as they can be dangerous depending on the medical condition of the patient, are often overused, and are not 100% effective. They have chosen to endorse the Licemeister comb. Really all you need is a comb with teeth that are as close together as possible (this is to physically drag the nits off your hair), but having one with a cool name couldn't hurt.

Although I would tend to agree with the AAP over the NPA, I must admit that the NPA website is full of wonderful treasures. There's a page with a bunch of educational videos, you can even observe an effective comb out! And my personal favorite is the lice e-card. I believe I have some e-cards to send now...

BUG WEEK: Day 5- I'm feeling Lousey

Pediculus humanus... body or head louse...

The body louse lives in the seams of clothes and is associated with war, famine, close living quarters, and elementary school. Today's post actually covers a disease of great historical significance. Please, read on...

1. Borreliae recurrentis-- humans are the reservoir, but lice are the vectors
- recurring fevers, just like the other Borrelia infections


2. Rickettsia prowazekii-- humans are the reservoir, but lice are the vectors
- TYPHUS!
- there are a few different types of typhus, each of which has different vectors, but epidemic typhus, which is transmitted by body louse, is the most serious
- the louse bite an infected person, the bacteria multiply within the louse belly, then it is excreted in feces when the louse is feeding on the next human, the human scratches the itchy louse bite, and any broken skin has now become a site of inefction
- a one to two week incubation period is followed by sustained high fevers, muscle aches, vasculitis, multiple organ disease, AND SKIN FINDINGS!
- also heart failure, shock, and death.
- early light rose colored macules start on trunk and spread to extremities, they blanche early, but later turn dull and red, they can spread everywhere but the palms and soles
- of course, with any vasculitis, you can get petechiae as well
- Wikipedia has a nice summary of the historical significance of typhus (all the historical figures killed by this disease and all the wars that it appeared in... which is pretty much every war up to World War II, when we got a vaccine)

BUG WEEK: Day 4- Tick talk (cont.)

Yesterday just about wore me out with all the tick stuff. But we shall press on...

Ixodes ticks also carry:
1. Ehrlichia-- no skin findings, presents as fever, HA, jt point, malaise... your classic fever of unknown origin
- the tick is the vector and the reservoir includes dogs, foxes, coyotes, deer, and rodents
- seen in the NE US
- infects macrophages, difficult to culture, but can possibly see microorganism in cells on blood smear

2. Babesia-- no skin findings, hemoprotozoan parasite (often confused with malaria), most infections are asymptomatic, but can produce fever, chills, sweating, myalgias, fatigue, hepatosplenomegaly, and hemolytic anemia after a 1 to 4 week incubation period
- the tick is the vector and reservoir
- seen in the NE and Midwest as well as CA and WA
- infects red blood cells, can be seen on blood smear

The soft tick Ornithodoros carries:
1. Borreliae hermsii-- no skin findings AND the tick falls off by itself, so most people don't know they had a bite at all
- presents a lot like Ehrlichiosis with recurring fevers
- western US


Hard ticks can also transmit...
1. ROCKY MOUNTAIN SPOTTED FEVER (Rickettsia rickettsii)--finally some skin findings!
- contrary to popular belief, it is most common in the Appalachians, but is seen in the Rocky Mountains, Central and South America
- can be very severe
- stages of disease: fever, malaise, muscle aches -> classic palms and soles rash -> systemic vasculitis
- the tick is the vector and rodents or dogs are the reservoir



The lone star tick (Amblyomma americanum) is pretty distinctive with that big colored dot on its back. It has one ill-defined disease association...
1. Southern Tick-Associated Rash Illness (STARI) (this one I didn't learn about in school, but found on the CDC's web page)-- skin findings again!
- it looks just like erythema migrans and can be easily confused for Lyme disease
- but the CDC says that the lone star tick does not carry Borrelia burgdorferi
- my lit search only came up with 3 articles on pubmed

Masters E, Granter S, Duray P, Cordes P. Physician-diagnosed erythema migrans and erythema migrans-like rashes following Lone Star tick bites.
Arch Dermatol. 1998 Aug;134(8):955-60.

- this one claims to have isolated B. burgdoferi in lone star ticks infesting the farm of a person with a tick bite and erythema migrans, so it looks like lone star ticks could transmit lyme disease. it also looks like no one cares to find out more since there is not much research on this topic
- these ticks are in the southeast and mid south


Finally, the last tick-borne illness...
The hard tick Hyalomma carries one virus...
1. Crimean-Congo Hemorrhagic Fever from the Nairovirus (of the Bunyavirus family)-- some skin findings!
- petechiae, flushing, jaundice can all be found (which kind of go with the hemorrhagic fever thing)
- the tick is both reservoir and vector
- most commonly found in Eastern Europe, particularly Russia (but also in China and India)
- it presents like a lot of the other diseases discussed today with high fever, joint pains, headache, and vomiting

That's all for the ticks!

BUG WEEK: Day 3- Tick talk

Often a fair amount of time elapses before people realize they have a tick on them. This goes back to yesterday's post, where I listed the most common bug bites that are painless. (Technically, ticks aren't even bugs. They have eight legs, making them arachnids. Bugs have 6 legs.) Unlike bed bugs, ticks do not usually elicit an allergic response, so there's no itchiness to alert one to the presence of the feeding tick. There are a few things I want to talk about with ticks...
1. The different types of skin reactions they elicit
2. The different diseases that they carry and transmit
3. The regions of the country where you will find certain ticks
4. How long they have to be attached to transmit disease
5. When to give antibiotic prophylaxis
Hopefully I'll get through everything tonight.

There are two kinds of ticks: hard ticks (Ixodae) and soft ticks (Argasidae). Mostly hard ticks are responsible for disease transmission. I'm going to try to minimize the tick pictures I post because I think they're gross.


Erythema chronicum migrans is associated with Lyme disease. You see multiple large red patches that are clear in the middle. The skin reaction is in the early stages of the disease and resolves on its own. So you may see a patient within the first few weeks of infection that has the skin findings, but after that, you'll have to elicit the history about the skin findings. Judging by how long it takes to get into see a dermatologist these days, I bet you're more likely to see patients who had the rash when they made the appointment, but it resolved before they made it into the office. I got the picture from DermAtlas

LYME DISEASE (Borreliae burgdoferi)- The most well known of all the tick-borne diseases. So, I didn't realize that there was a commercially-available Lyme disease vaccine between 1998 and 2002 (LYMErix). It contained a surface antigen of the bacteria that caused antibody production in humans. The neat part about the vaccine is that the antibodies actually fight the bacteria in the tick instead of in the human. When the tick attaches to the human, it does not transmit the bacteria until it regurgitates some blood and saliva. This doesn't happen until 18-24 hours after the original bite. During this time, the antibody immune response is going on inside the tick, so that when it regurgitates, it should not have active bacteria in the regurgitant. I guess that living in Florida and Texas aren't close enough to the tick belt to get you the vaccine. But it looks like I didn't miss much, since they took the vaccine off the market because of reports of a vaccine-induced, treatment-resistant, chronic arthritis.


The ticks responsible for Lyme disease are from the Ixodes genus and are commonly known as black-legged ticks. They are merely the vector for transport, as they acquire the disease from white-footed mice, deer, and other mammals. When the infected tick bites humans, it transmits the disease 18-24 hours after biting. You have almost a full day to find the tick before it transmits disease! This disease is most common in the northeast and Wisconsin, but it can be found in the Northwest as well.

It can present clinically as a relapsing fever with general symptoms of malaise and muscles aches or it can present as classic Lyme disease. This involves three stages. The first is relapsing fever with erythema migrans. The second is disseminated disease which could include arthritis, carditis, and neurologic disease. This happens after the little spirochetes screw their way down to the blood stream and spread throughout the body. The third stage is chronic arthritis. This is if you don't treat it. Treatment is with doxycycline or penicillin. Antibiotic prophylaxis after a tick bite is quite controversial.

RB Nadelman, J Nowakowski and D Fish et al., Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after an Ixodes scapularis tick bite, N Engl J Med 345 (2001), pp. 79–84.

This study showed that one dose of Doxycycline 200 mg was effective in preventing Lyme disease. They did not claim to prevent all cases, but they did have statistically significant results between the placebo and doxy groups. They showed an efficacy of treatment of 87%, but the 95% confidence interval is 25-98%. Confidence intervals this wide weaken the results of the study.

Maraspin V, Lotric-Furlan S, Strle F. Development of erythema migrans in spite of treatment with antibiotics after a tick bite. 2002 Jul 31;114(13-14):616-9.

This study showed a 0.14% rate of erythema migrans after prophylaxis, which sounds pretty good to me, but it doesn't seem like everyone agrees...

D Volkman, Prophylaxis of tick bites, Lancet Infect Dis 7 (2007), pp. 370–371.

Volkman was pretty adamant that the NEJM study was flawed in how it measured its outcomes.

Anyway, it seems like the consensus is to prophylax for Lyme disease as it shows good results and is low-risk. But this can be tailored depending on where in the country you are.

OK, that's enough for today. I'll do more tick-borne diseases tomorrow.

BUG WEEK: Day 2- Is this a bug bite?

Usually you can tell when you get a bug bite because you feel the pinch of the bite. But there are a few bugs/arachnids that inject a cytotoxin or numbing poison while biting so that you cannot feel the pinch of the bite. They are:
1. bed bugs
2. brown recluse
3. ticks

We'll just discuss bed bugs today...


BED BUGS (Cimex lectularius)


- blood-sucking, but do not transmit disease, can get multiple bites from one bug, nocturnal
- superficial bites, produce wheal +/- pustules and itching, usually in groupings
- look similar to bites from fleas, body lice, and scabies
- prefer humans, but can be transmitted on dogs and cats, clothing, and luggage
- look for excrement on the seams of the mattress and look for bugs up near head of bed around mattress frame or box spring
- treat with topical steroids for itching and topical antibiotics if pustules or broken skin
- although relatively harmless, they can give people delusional parasitosis (make you feel itchy, even when there aren't bugs on you)... which I think I have after reading all about bed bugs

BUG WEEK: Day 1- How to remove a tick

Today I had a great lecture about the basic bugs that cause dermatological lesions. In spite of making me feel itchy all over, I actually learned a lot. In fact, it inspired me to dedicate a week to the creepy crawlies of dermatology.

But today, I have a very specific topic... HOW TO REMOVE A TICK. There was some discussion of this at lecture today, where the experienced opinion is that heat should be applied to the tick in the form of a heated paper clip in order to cause its release of the skin. However, my friends and I were discussing this apparently controversial topic, and it was brought to my attention that heating the ticks stresses it and causes it to regurgitate material into the skin before letting go. The method my freind recommended was to grab the tick as close to the skin as possible and just pull it out. She just completed a back country trip in Minnesota, which involved many a tick, so she had considerable experience in this area. My concern with just pulling the tick out is that there will likely be foreign material left in the skin. Which is worse, some mouth parts or regurgitated tick saliva in your skin?

I decided to do a lit search on pubmed...

Removal of ticks: a review of the literature
Health Protection Agency Centre for Infections, London, UK

Oteo JA, Martínez de Artola V, Gómez-Cadiñanos R, Casas JM, Blanco JR, Rosel Evaluation of methods of tick removal in human ixodidiasis. L.Rev Clin Esp. 1996 Sep;196(9):584-7.

The current opinion is that the tick should be grasped as close to the skin as possible, preferably with curved forceps and pulled straight out with constant force. This minimizes the chance for foreign material to remain in the skin and because the tick is removed immediately, it will not have the chance to regurgitate any material. If the barbed mouth piece is left behind, the chances for secondary infection and allergic response are increased. Multiple studies have been done on tick removal with measured outcomes including rates of complications (transmitted diseases and secondary infections) as well as retained mouth parts.

1. suffocating the tick- because ticks have a low respiratory rate, it usually takes a while to suffocate them, giving the tick more time to transmit disease
2. chemical irritants- in the studies, the ticks did not consistently detach
3. heat- in the studies, the ticks did not consistently detach
4. unscrewing the tick- higher likelihood of retained mouth parts
5. commercially available devices with grooves, like this one were better for immature ticks, but left behind mouth parts of mature ticks
6. forcep or finger removal of tick from point of attachment- RECOMMENDED METHOD

The WHO and the CDC recommend the forcep removal method. Here is an image and text from the CDC web page.

Remove a tick from your skin as soon as you notice it. Use fine-tipped tweezers to firmly
grasp the tick very close to your skin. With a steady motion, pull the tick’s body away from your skin. Then clean your skin with soap and warm water. Throw the dead tick away with your household trash.

Avoid crushing the tick’s body. Do not be alarmed if the tick’s mouthparts remain in the skin. Once the mouthparts are removed from the rest of the tick, it can no longer transmit the Lyme disease bacteria. If you accidentally crush the tick, clean your skin with soap and warm water or alcohol.

Don’t use petroleum jelly, a hot match, nail polish, or other products to remove a tick.