Posts Tagged ‘tick-borne diseases’

Tick-borne Disease part four: the chronic Lyme Disease controversy

Monday, April 30th, 2012

Sometimes you need an expert panel to resolve a controversy

A March 27, 2012, Wall Street Journal article, "This Season's Ticking Bomb,"predicted that the unusually warm weather most of the country has been experiencing meant we would also see many more cases of tick-borne diseases, If you click on the link, be sure to look at the section called "View Interactive" to get to a series of suggestions on reducing your family's risk of tick bites.

The article itself talked mainly about Lyme disease. There is an International Lyme and Associated Diseases Society (ILADS), but much of their Lyme disease website information was from 2006.  They are on one side of a major medical controversy, how to care for patients who have had Lyme disease and continue to have problems, especially with short-term memory, fatigue, or musculoskeletal issues, well after they have been appropriately treated with short-term antibiotics.

Two articles were published on this subject in 2007-8: the first one, "Chronic Lyme Disease: an appraisal"  is available online; the other, "A Critical Appraisal of Chronic Lyme Disease," appeared in the New England Journal of Medicine.

The real question is whether the bacteria involved, Borrelia burgdorferi, remains in the body of a patient after relatively short-term antibiotic therapy and if a considerably longer course of drug treatment is warranted. The ILADS says, "Yes" to both questions and refers back to a Harvard & Tufts study published in the Annals of Internal Medicine in 1994.

The most recent CDC online information states that 10 to 20% of those who receive standard therapy for Lyme disease will have some lingering symptoms. However they term this "Post-treatment Lyme disease Syndrome." I found that European cases of Lyme and similar diseases are usually caused by our Borrelia borgdorferi's cousins; data from that literature may not be relevant here.

In November 2006, the Attorney General of Connecticut (CAG) pushed the Infectious Disease Society of America (IDSA) into a detailed review of their Lyme Disease guidelines by starting an investigation to decide if they had violated existing antitrust laws. By April 2008, the IDSA and the CAG agreed to end the probe by convening a review panel, with members from Duke, the NIH, Dartmouth, the U.S. Navy, Baylor, Tulane and other centers, to decide if the original guidelines had been based on sound medical/scientific evidence and if they needed changes. An MD, PhD medical ethicist screened panel members for any conflict of interest. A public hearing was held to include other viewpoints. The Final Report of the Review Panel was published in April, 2010.

Some will think the decision ties their doc's hands.

It basically upheld the 2006 IDSA guidelines, but added 1). In some cases (non-pregnant adults or kids 8 or older who've had a tick of the Lyme-carrying species attached for 36+ hours in an area with high infectivity rate of ticks with B. burgdorferi), a single dose of doxycycline (if they have no allergy to this drug) may be given  if the tick was removed within 72 hours; 2). Antibiotics are appropriate for adults and children 8 or older with early, uncomplicated Lyme disease; 3).  "Reports purporting to show the persistence of viable B. burgdorferi organisms after treatment with recommended regimens for Lyme disease have not been conclusive or corroborated by controlled studies." and 4). "The risk/benefit ratio from prolonged antibiotic therapy strongly discourages prolonged antibiotic courses for Lyme disease.

And at the end of the report, they mentioned a disease I'd never heard of; I'll do some more reading and write about it later.





tick-borne disease part 3: Vanilla Lyme

Sunday, April 29th, 2012

I'm finally ready to write about Lyme disease and will start with the basics; it results from the bite of a tiny tick and causes well over 20,000 cases per year in the US. It's most common in the North-East and the Middle-West, most frequently affects kids under 16 (especially girls--ticks can hide in long hair) and can be prevented (DEET to keep ticks away; post-hike "tick checks"); prompt antibiotic treatment is indicated if signs or symptoms/history suggest this entity.

you have to look closely

I'll save the controversy about post-treatment Lyme disease syndrome, AKA Chronic Lyme Disease, for another post as that issue deserves its own discussion.

We first heard about Lyme disease some years back when a relative was afflicted by a severe case of the illness. One of the best resources I've subsequently found on Lyme came from an emeritus at the place I got my formal medical training, the University of Wisconsin, now termed UW-Madison. Dr. Kenneth Todar, a PhD in the Department of Bacteriology, has a superb online textbook and his chapter on Lyme Disease is an extremely helpful reference.

The initial realization of the disease itself happened thirty-seven years ago. The website for NIAID, the National Institute of Allergy and Infectious Diseases has a great, though somewhat convoluted, detailed history of Dr. Willy Burgorfer's isolation of the spirochete bacteria that would eventually be named for him.

In brief, there had been a 1975 outbreak that resulted in a considerable number of children living in or near the town of Lyme, Connecticut, being diagnosed with juvenile rheumatoid arthritis. The Yale physician looking for the cause of these Lyme disease cases realized most occurred in children who spent time in wooded areas and whose initial symptoms occurred in the midst of the tick season, summer. He thought the deer tick might be involved and, eventually, Dr. Burgdorfer  found the spirochetes in deer ticks sent to him from the affected area.

IDSA,  the Infectious Disease Society of America, has a one-pager titled "Ten Facts You Should Know About Lyme Disease" and the New York Health Department has a similar short discussion of Lyme Disease.

one example of a typical rash

To reiterate the concepts I think are crucial:  the groups involved, kids under 16 with more girls than boys, plus adult men;. the areas of the country: 93% of cases occur in ten states: Connecticut, Delaware, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island and Wisconsin; the fact that early diagnosis is clinical (antibodies develop later); the tiny size (two mm) of the tick nymphs which usually are the agents for transmission of the bacteria; the difficulty in diagnosis unless the characteristic rash is present; and the need for prompt antibiotic treatment in prevention.

Symptoms begin to show anywhere from a few days to a month after the bite, but, in most cases, the tick itself has to remain attached for a day and a half to transmit the bacteria and there is no person to person spread of this disease. Early signs, in the absence of the characteristic rash, are very non-specific.

There is a sizable percentage of patents with Lyme who have long-term sequelae. I'll write about them next time.

Tick-borne diseases: part one: Colorado ticks and related diseases

Saturday, April 21st, 2012

a well-fed tick

The Wall Street Journal recently published an article titled "This Season's Ticking Bomb,"  discussing the rise of tick-borne diseases, especially focusing on Lyme disease. It said two factors have been important contributors to this global trend: people have moved into turf harboring animal species which often carry ticks and, simultaneously, some kinds of those animals, e.g., squirrels, deer and mice, have increased their numbers.

I must confess I haven't worried much about Lyme disease since our 1999 move to Fort Collins, Colorado, where our back porch is at an altitude of 5,206 feet. Then I found an online 2012 fact sheet from Colorado State University; its subject, "Colorado Ticks and Tick-borne Diseases" gave me pause until I read, "No human cases of Lyme disease have originated in Colorado."

I was amazed to find that ticks here are especially common at higher altitudes; I would have guessed the opposite was true.

We have two species of Colorado ticks that are most relevant to humans: the American dog tick and the Rocky Mountain wood tick. They are three-host blood-feeding parasites, moving from rodents or other small mammals to dogs or deer typically and then, when available, on to human hosts. We're more likely to encounter them in spring or early summer on paths through grassy areas or the brushy zones near the edges of field and woods.

I initially was concerned about the risk of Rocky Mountain spotted fever (RMSF), but it's actually fairly rare here and most common in North Carolina, Oklahoma, Arkansas, Tennessee and Mississippi. From 2,000 to 2,500 cases occur a year in the US with those five states accounting for 60%. They see 19 to 77 cases a year per million while Colorado has 0.2 to 1.5 cases per million. The CDC webpage on RMSF notes the overall incidence of the disease has gone up considerably since 1920, but the fatality rate has plummeted. But in eastern Arizona, through 2009, over 90 cases were noted in a previously RMSF-free area. Ten percent of those who developed RMSF died and there was a marked association with communities with free-roaming dogs.

Colorado Tick fever is seen more frequently in my state than any other infection related to tick bites. It's a viral disease with up to 15% of our campers being exposed, but is not as serious as many other tick-bite-caused illnesses. It usually goes away without causing complications, but 5-10% of those infected with the virus can develop encephalitis, meningitis or, rarely, hemorrhagic fever. Children are more prone to severe acute disease and more likely to have the nervous system complications, but most kids who contract this illness get well quickly. About 70% of adults over 30 may have prolonged symptoms.

make your body a no-tick zone

Half of those who develop Colorado tick fever have a so-called "saddle-back" temperature curve with initial fever then normal temperature followed by a single fever recurrence.

 I'm in the prime zone for this disease; it normally occurs in those living or traveling to altitudes of 4,000 to 10,000 feet. So it's important for me and others living or visiting here to wear protective clothing, use DEET as a tick repellent, do a "tick check" after a day outdoors and, if any are found to remove them properly with blunt tweezers.