5-97
Follow-up Actions
Wound Care: Do not perform incision and drainage of suppurative nodes.
Evacuation/Consultation Criteria: Transport to a hospital level of care. Serology can be used to confirm
diagnosis.
Zoonotic Disease Considerations
Principal Animal Hosts: Wild rodents (rats, squirrels, chipmunks, prairie dogs), rabbits, and domestic cats.
Clinical Disease in Animals: Fever, pneumonia, lymphadenitis
ID: Rat Bite Fever
LTC Glenn Wortmann, MC, USAIntroduction: Caused by infection with Streptobacillus moniliformis or Spirillum minor, rat-bite fever is
transmitted by the bite of a rodent and has worldwide distribution. Contaminated water and milk have been
implicated in outbreaks. Incubation period is 3-10 days.
Subjective: Symptoms
Fever, chills, headache, myalgias, arthralgias and rash
Focused History: Do you recall being bitten by a rat? (typical history) How long ago were you bitten by a rat?
(incubation period is 3-10 days) Do you have a rash? (typical in most patients)
Objective: Signs
Using Basic Tools: The rash can be maculopapular, morbilliform or petechial, and erupts over the palms,
soles and extremities. Approximately 50% of patients develop an asymmetric polyarthritis.
Using Advanced Tools: Lab: Culture of blood, joint fluid or pus may demonstrate organism.
Assessment:
Differential Diagnosis: Other potential causes of fever/rash are varied, and include measles,
meningococcemia, Rocky Mountain Spotted Fever and secondary syphilis.
Plan:
Treatment: The presence of fever and rash after a rat-bite should suggest a diagnosis of rat-bite fever
and treatment should be given empirically. For moderately to severely ill patients, use procaine penicillin G
600,000 units IM or IV penicillin every 12 hours. For mildly ill patients, amoxicillin 500 mg po tid x 14 days
is probably adequate. For penicillin-allergic patients, tetracycline 500 mg po every 6 hours or doxycycline
100 mg po every 12 hours may be given.
Patient Education
General: Avoid rat bites
Activity: As tolerated
Diet: As tolerated
Medications: Occasional gastrointestinal side effects. Tetracycline and doxycycline should be avoided in
children and pregnant women.
Prevention and Hygiene: Avoid rat bites.
No Improvement/Deterioration: Return for evaluation.