Intern Report 5.14

Case Presentation by Dr. Jamie Kenney

HPI: 5 year old male presents to the ED complaining of a rash.  According to his parents he recently returned home from visiting his grandparents in Tennessee and has been complaining of “not feeling well” for the 4 days.  He has had a decreased appetite with nausea and vomited 3 times yesterday.  He is also complaining of feeling “hot” but his parents did not take his temperature at home.  They first noticed the rash yesterday evening that began on his hands and feet and has since spread to his abdomen.  Rash does not itch, no blistering or pus formation.  He was given Tylenol at home with no relief.  Patient is also complaining of a severe headache 9/10, pulsating, does not radiate to neck.  No one else in the family has similar symptoms.

Review of Systems:

Constitutional: Positive for “feeling hot” and fatigued

Head: Negative for neck pain, positive for headache

Eyes: Negative for redness, pain or discharge

ENT: Negative for runny nose, ear pain or sore throat

Cardiovascular: Negative for palpitations or chest pain

Lungs: Negative for shortness of breath or cough

Gastrointestinal: Positive for nausea/vomiting and abdominal pain

Musculoskeletal: Positive for body aches and swelling, negative for joint deformities

Skin: Positive for rash, no ulcers or lesions

Neurologic: Negative for numbness or tingling

Past Family, Medical and Social History

Medical Hx: Asthma

Surgical Hx: None

Medications: Albuterol

Allergies: NKDA

Examination of Organ Systems and Body Areas

VS: BP 90/56 HR115 RR14 Temp 40.1 Pulse ox 98% on room air

General: Patient is well nourished, in mild distress.  He is lying on the stretcher in the fetal position and appears uncomfortable.

HEENT: NC/AT, EOMI, PERRLA, non-icteric, neck supple no meningeal signs

Mouth: Dry mucus membranes, no lesions or vesicles

Cardiovascular: S1/S2, tachycardic, no m/r/g

Respiratory: CTABL, no wheezing or rhonci

Gastrointestinal:  Hyper-active bowel sounds, TTP diffusely, hepatomegaly, no masses, no rebounding or guarding

Musculoskeletal: NROM, TTP over all four extremities.  No cyanosis, clubbing.  Subtle non-pitting edema of lower extremities.

Skin: Diffuse palpable purpura located over all four extremities including the palms and soles.  Rash is non-blanching, non-vesicular and symmetric.  (See Images Below)

Neurologic:  Patient is awake, oriented x 3.  Not interactive but responds appropriately to all questions.  Strength 5/5 in upper extremities, 4/5 in lower extremities. Normal finger to nose and heel to shin.  Reflexes +2 and symmetric bilaterally.  Gait was normal.

Laboratory Values

WBC: 8 Hgb: 10.2 Hct: 35 Plt: 90

Na: 124 K 3.8 HCO2: 24 Cl: 102 BUN 18 Cr 0.9

INR: 2.0  PT: 18 PTT: 60

AST: 100 ALT: 180

IMAGES:

 

 

QUESTIONS:

1) What is the Diagnosis?

2) When does the rash typically appear?

  1. Within 24hrs of exposure
  2. Immediately after the fever breaks
  3. One to two weeks after exposure
  4. On the third to fifth febrile day

3) Treatment for this patient consists of:

  1. Doxycycline PO 2.2mg/kg Q12 hrs
  2. Vancomycin/Cefepime pharmacy to dose
  3. Doxycycline IV 100mg BID
  4. Ampicillin/Sublactam IV 3g Q6hrs

DISCUSSION 

This patient has Rocky Mountain Spotted Fever (RMSF).  RMSF is defined as an acute, febrile, systemic tick-borne illness caused by Rickettsia rickettsii that can be found in North, South and Central America.  Within the United States the most frequent occurrences of RMSF occur in Oklahoma, North Carolina, South Carolina, Tennessee and Pennsylvania (hence the hint with Blue Ridge Mountains).  The history of RMSF dates back to the late 1800’s and was known by the White settlers as “black measles.”  Within the past decade the number of reported cases has more than tripled, especially in suburban areas.  RMSF ranges in clinical severity from a subclinical illness to a fulminant disease with vascular collapse.  There are approximately 40 deaths per year in the United States with the most at risk age groups being children younger than 10 years and adults over 60 years old.

Rickettsia rickettsii are obligate intracellular bacteria that can invade both the nucleus as well as the cytoplasm.  Ticks are the vectors for RMSF with the American Dog Tick, Dermacentor variabilis and the Rocky Mountain Wood Tick, Dermacentor andersoni being the most common species within the United States.  Ticks will feed on any warm blooded mammal transporting the organism from animals to humans.  After R. rickettsii enters the host the organisms it will invade and multiply in the vascular endothelial cells.  They continue to invade into deeper tissues disrupting vessel walls and infecting vascular smooth muscle.  The organisms are able to move from cell to cell by actin-based motility.  Their invasion causes the release of tissue plasminogen activator and von Willebrand factor further leading to microhemorrhage, microthrombus formation, and increased vascular permeability.  These extensive vascular lesions are what cause most of the features associated with RMSF.  Increased small-vessel permeability results in hypotension, edema and increased extravascular fluid space.

Clinical features of RMSF are initially vague and it is hard to make the diagnoses without a high index of suspicion.  The “common” triad is fever, rash and known tick bite.  However it is rare that emergency physicians will have all three and only 3-18% of all cases actually have the triad.  Early symptoms include sudden onset of fever, severe headache, nausea, vomiting and myalgias.  The rash, present in 88% of patients with RMSF is the most distinctive feature of the disease.  It normally appears on the 3rd to 5th febrile day.  Vasculitis and changes in vessel permeability cause the early features of the rash and subsequent petechial and hemorrhagic lesions are secondary to thrombocytopenia.  The rash typically starts on the wrist and ankles then begins to spread centripetally to the trunk within 6-12 hours.  One unique feature of the rash is its presence on the palms and soles (please refer to pictures above).  Initally the rash consists of small red macules that worsen when a warm compress is applied.  After 2-3 days it becomes maculopapular and no longer blanches with pressure.  Without the appropriate treatment the lesions will coalesce to form large areas of ecchymosis that eventually slough off and form indolent ulcers.

RMSF has the potential to spread rapidly throughout the body if not treated properly.  As R. rickettsii continues to invade the vasculature it can lead to some life threatening conditions such as myocarditis, arrythmias, interstitial pneumonitis, hepatosplenomegaly and several neurologic manifestations ranging from headache to seizures and coma.

Diagnosis in the emergency department relies heavily on physicians being aware of the prominence of the disease within their region.  Clinic evidence is the mainstay of diagnosis within the ED.  Initial laboratory testing may show some non-specific abnormalities such as hyponatremia, prolonged PT/PTT, thrompocytopenia and elevation of LFTs if hepatomegaly is present.  A definitive diagnosis requires positive results on one or more of the following tests: serologic serum antibody titer reactive with R. rickettsii, skin biopsy or direct isolations and identification of the organism in a cell culture.

Treatment consists of supportive care and antibiotic therapy.  Antibiotic therapy is most effective when given within the early stages of the disease; when the rash first appears or prior to that.  Doxycycline is regarded as the therapeutic agent of choice.  The dosing for adults is 100mg BID PO/IV and for children (<45kg) 2.2mg/kg PO Q12hrs.  Chloramphenicol should be used for patient whom are known to be allergic to tetracyclines and for pregnant women unless they are near term.  Therapy should last for 7-10 days or until the patient is afebrile for 2-5 days.  Steroids are a controversial topic and are currently not recommended.  Without appropriate antibiotic treatment fatality rates rise to 25% from 5%.

All cases of RMSF should be reported to the CDC.

References:  Rosen’s Emergency Medicine 7th Edition, Tintinalli’s Emergency Medicine 7th Edition and www.dermatlas.jhmi.edu (pictures)

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