for
LYME DISEASE
Developed for the
Aerospace Medical Association
by their
constituent organization
American Society of Aerospace Medicine Specialists
Overview: Lyme disease is the
most common tick-borne disease in the United States (US) and
Three
distinct foci occur in the
The
ticks have larval, nymphal and adult stages, each stage requiring a blood
meal. In the Northeast and North Central
US, an efficient cycle of infection of B.
burgdorferi between nymphal ticks and white footed mice yields a high
frequency of infection during the spring and summer months in humans. An abundance of deer, the adult ticks
preferred host, fulfill a similar role in the Northeast. I. scapularis,
also know as I. dammini,
serves as the tick vector. The
principle vector in the Northwestern US is I.
Even
though the likelihood of infection is twice as high in adult ticks as in the
nymphal stage, most cases of transmission of early Lyme disease occur in the
spring and summer months when the nymph is seeking a blood meal. Adult ticks are much larger and easier to
identify and remove, prior to transmission of infection. Animal studies confirm that approximately 36
- 72 hours are required for transmission of the infection to the animal host
once the tick has attached to itself to the host. During this time spirochetes in the midgut of the tick multiply and migrate to the
tick’s salivary glands, in preparation for transmission to the animal host. Only ticks that are partially engorged
with blood are associated with the development of erythema migrans at the site
of the bite.
Lyme
disease occurs in three broad stages.
The clinical symptoms of each stage may overlap. Individuals may also present in a later stage
without presenting with symptoms of an earlier stage. The most common clinical manifestation of the
first phase is EM. EM occurs between 3 and 30 days, although it most commonly
develops between 7 and 14 days. Seventy
five to 80 percent of patients with erythema migrans present with a single
primary lesion. This lesion is usually
greater than or equal to 5 cm in diameter, often with a central clearing,
bull’s-eye or target like appearance.
Approximately 45 percent of patients with erythema migrans have spirochetemia. Spirochetemia is not related to the size or duration of the
presenting skin lesion. Hematogenous
dissemination from the primary infection site may yield secondary lesions. Symptoms during the primary stage often
resemble those of a viral infection, including arthralgias, fatigue, headache and neck pain.
Fever may or may not be present.
Respiratory and gastrointestinal symptoms are atypical. Erythema migrans spontaneously resolves in
approximately four weeks without treatment.
The
second stage is manifested by dissemination of the disease within days up to 10
months following the initial tick bite.
It is associated with hematogenous spread of the spirochete to
extracutaneous sites. Sixty percent of
untreated patients with erythema migrans will progress to mono or
oligoarticular arthritis, usually involving the knee. Ten percent will manifest with neurologic
complications, the most common of which is facial-nerve palsy. Five percent will manifest with cardiac
complications, usually varying degrees of atrioventricular block.
The
third stage includes late disease which may occur months to years following the
initial tick bite. Individual’s
experiencing joint involvement may sustain several brief attacks of arthritis
with the potential for persistent joint inflammation. In up to 10 percent of cases, the arthritis
may persist for months or years despite 30 days of intravenous (IV) or 60 days
of treatment with oral antibiotics.
Large joints, especially the knee are susceptible, presenting with joint
swelling and pain.
Neurologic
involvement may occur within weeks.
Acute neuroborreliosis may develop in up to 15 percent of untreated
patients in the
Cardiac
involvement may occur several weeks after the initial onset. Approximately five percent of untreated
patients experience cardiac involvement, to include atrioventricular block,
acute myopericarditis, mild left ventricular dysfunction and rarely
cardiomegaly or fatal pancarditis.
Diagnosis
in the
Treatment
recommendations during the first stage of Lyme disease include: doxycycline 100 mg twice daily for adults;
amoxicillin 500 mg three timed daily for adults; and cefuroxime axetil 5000 mg
twice daily for adults. The duration of
therapy has traditionally been three weeks, although some studies suggest that a 10 to 14 day duration of therapy may be as effective. Doxycycline is not recommended for children
under 8 years of age or for pregnant or lactating women. Of these three antimicrobials, only
doxycycline is also effective against A. phagocytophilum
infection (human granulocytic ehrlichiosis), also a tick born illness. Individuals with chronic musculoskeletal
pain, neurocognitive symptoms or both that persist after antibiotic treatment
for well-documented Lyme disease may have considerable impairment in their
health-related quality of life. However
further treatment with an extended (90 day) course of antibiotics in a
controlled clinical trial in individuals without evidence of persistent
infection by B. burgdorferi received
no added benefit over those who received placebo. A substantial increase in the
risk of morbidity and even death in patients secondary to extended
antimicrobial therapy was noted in this study.
Second
(early disseminated) and third (late) stages of Lyme disease may be treated
with intravenous (IV) ceftriaxone, a third generation cephalosporin. Recommended dosages include 2 g once daily in
adults. Similarly, cefotaxime 2 g every
eight hours is also recommended in adults.
Additionally penicillin G divided into doses given every four hours in
patients with normal renal function may be effectively used. Eighteen to 24 million units per day in
adults is the recommended dosage. Recommended
duration of IV therapy is two to four weeks.
Four weeks is the current standard in many communities, although there
is no evidence to support greater efficacy of four versus two weeks. There is also no evidence that treating for
more than four weeks is beneficial.
Prevention
may be accomplished through avoidance of tick-infested areas, wear of protective
clothing, the use of repellents and acaricides, tick checks and modifications
of landscapes in or near residential areas.
Additionally a vaccination for Lyme disease has been developed. It utilizes a recombinant OspA
in adjuvant and is commercially available in the
Aeromedical Concerns The primary aeromedical
concerns of this disease are its debilitating side-effects in regards to the
neurologic, cardiovascular, and arthritides that may result. If an aircrew member had one or more of these
manifestations that did not resolve with treatment, he may possibly be removed
from flight status, unless functional enough to be cleared by after expert
evaluation. Neuropsych testing should be
accomplished for individuals in the
Medical Work-up:
Aeromedical Disposition:
Air Force: In the Air Force, any cardiac
manifestations are disqualifying for all classes of aviation. In addition, all aviators are grounded while
under treatment. Only in the case of
full resolution of acute (stage I) Lyme disease may the flier be returned to
flight status without an aeromedical waiver.
Waiver may be considered for stage II and III Lyme disease, depending on
the success of the therapy. In fliers
with residual symptoms, a full evaluation is required as is any case of
disseminated disease. The experience of
the entire DOD is scant, numbering less than 10 aircrew member cases.
Army: Waiver is not required for acute Lyme
disease, although patients should be DNIF during antibiotic therapy. Any case of disseminated Lyme disease,
substantiated by serology requires waiver.
CNS findings will require complete resolution and a 3-month period of
observation prior to consideration of waiver recommendation.
Navy: NOMI evaluation is
recommended for all cases of suspected complicated disseminated Lyme
disease. Uncomplicated erythema migrans
in the appropriate clinical setting can be diagnosed and treated at the local
level. It is not considered
disqualifying if adequately treated.
Civilian: The civilian disposition of this
condition will entirely depend on the manifestations of the involved organ
system. If Lyme disease is diagnosed it
will need to be completely treated prior to any determination for medical
certification.
Waiver Experience:
Air Force: Review of AIMWTS data
base through May 07 revealed two waivers granted for fliers with a diagnosis of
Lyme disease. The first case was a 40
year old pilot who presented with a 22 month history of fatigue, fevers and
myalgias of unknown etiology. He was
eventually treated with antibiotics for a history of a rash similar to EM,
noted while on a family camping trip. His symptoms completely resolved within 3
weeks of the initiation of antibiotic treatment and he remained symptom
free. Despite a negative Lyme titer, a
presumptive diagnosis of Lyme disease was made.
The second case was a 41 year old command pilot who presented with a
progressively worsening audiogram and an abnormal Exercise Treadmill Test
(ETT). A presumptive history of
neuroborreliosis was made, based on serology testing. He was treated with 21 days of intravenous
(IV) ceftriaxone. Following this
treatment, his midrange frequency hearing loss was noted to stabilize. Repeat ETT was noted to be normal. He also underwent a left sided L4-5
discectomy for an L4-5 herniated nucleus pulposus (HNP), manifested by a mild
left foot drop. He experienced an
excellent recovery with the exception of minimal weakness of his left extensor hallucis longus, thought to have
no significant occupational impact.
Army: The Army’s Aeromedical Epidemiological
Data Registry was queried for the period of 1960 to 2009. This case series contains 160,000
individuals. This is a long span of time
during which aeromedical policy has evolved.
There were 33 cases of Lyme disease.
Of those, 28 were retained. Of
these 20 were rated aviators. Note that
flight applicants were included in the data set, but not considered as rated
aviators.
Navy: No numbers to report
at this time.
Civilian: The current Path Code system has the
same code for Lyme Disease and for Osteoporosis. Those numbers as of August 2009 are: 205 for
first class, 172 for second class and 666 for third class
|
ICD
9 Codes for Lyme Disease |
|
|
088.81 |
Lyme Disease |
References:
Klempner
MS. Two Controlled Trials of Antibiotic Treatment
in Patients with Persistent Symptoms and a History of Lyme Disease. N Engl
J Med. 2001; 345: 84-92
Lipschütz B. Zur Kenntnis der "Erythema chronicum migrans". Acta dermato-venereologica,
Nadelman RB.
Prophylaxis with Single-Dose Doxycycline for the Prevention of Lyme Disease after an IXODES
SCAPULARIS Tick Bite. N Engl J Med. 2001; 345:
79-84
Sigal LH.
Diagnosis of Lyme Disease. UpToDate. Online 15.1, March 12, 2007.
Sigal LH.
Treatment of Lyme Disease. UpToDate. Online 15.1, March 10, 2007.
Steere AC.
Lyme Disease.
N Engl J Med. 2001; 345: 115-125.
Sternbach G,
Dibble C. "Willy Burgdorfer: Lyme disease." J Emerg Med. 1996; 14
(5): 631-34.
Wormser
GP. Early Lyme Disease. N Engl
J Med. 2006; 354: 2794-2800.
Prepared
by Drs. Stephen Hingson and Karen Fox
12
Sep 09