Rickettsialpox

Rickettsialpox is prevented by controlling mice and their mites. Most cases have been reported in New York City and cities in the former Soviet Union. A skin lesion may be found at the site of the mite bite. Regional lymphadenopathy and later fever and rash occur.

CASES/YEAR
200 (US); 4,000 (Global)
CATEGORY
Arthropod-Borne
AGENT TYPE
Rickettsiae
OTHER NAMES
Vesicular rickettsiosis; Rickettsia akari infection;
ACUITY
Acute-Moderate
INCUBATION
6-15 days; [CCDM]
INITIAL SYMPTOMS
A skin lesion may be found at the site of the mite bite. Regional lymphadenopathy and later fever and rash occur. The vesicular rash has been mistaken for the rash of chickenpox. [CCDM]
PRECAUTIONS
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
EPIDEMIOLOGY:
Rickettsialpox is transmitted by mites from mice to people. The disease is prevented by controlling mice and their mites. Most cases have been reported in New York City and cities in the former Soviet Union. [CCDM, p. 520-1] Outbreaks are associated with rodent extermination when mites seek new hosts. [CDC Travel, p. 329]

FINDINGS
The fever starts 1-2 weeks after the mite bite. The papular rash appears 1-3 days after onset of the fever. Vesicles usually develop on the top of the papules. Rickettsialpox tends to be milder than other rickettsial infections. [ID, p. 1488] The fever lasts about one week and is associated with profuse sweating, headache, myalgia, and photophobia. The rash develops in the first few days of the fever, and it does not affect the palms and soles. Rickettsialpox is not known to be fatal. [Merck Manual, p. 1697] An eschar at the site of the mite bite can be found in more than 90% of cases, and it is associated with regional lymphadenopathy. Transient leukopenia and thrombocytopenia, as well as elevated liver enzymes, may be seen. [PPID, p. 2358] Some patients have nausea/vomiting, abdominal pain, cough, and conjunctivitis. The fever lasts for 6-10 days in untreated patients. [Harrison ID, p. 692]

DIFFERENTIAL DIAGNOSIS:
Rickettsialpox causes a vesicular rash along with a few other infections, e.g., smallpox, varicella, herpes zoster, herpes simplex, Queensland tick typhus, and African tick-bite fever. The last two are similar to Boutonneuse fever. [PPID, p. 2358]
DIAGNOSTIC
Serology; PCR; Immunostain of tissue from biopsy; [CCDM]
SCOPE
Worldwide in urban and rural cycles; [ID, p. 1488] In urban centers of the former USSR, South Africa, Korea, Turkey, Balkan states, and North & South America; [CDC Travel, p. 326]
SIGNS & SYMPTOMS
  • >fever
  • >myalgia
  • E pharyngitis
  • E rhinitis
  • G abdominal pain
  • G liver function test, abnormal
  • G nausea, vomiting
  • H leukopenia
  • H lymphadenopathy
  • H thrombocytopenia
  • N headache
  • O conjunctivitis, acute
  • R cough
  • S entry wound with lymph nodes
  • S lymphadenitis, acute
  • S papules or plaques
  • S rash (exanthem)
  • S skin blister or vesicles
  • S ulcer of skin
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
Inhalation
VECTOR
Mites
RESERVOIR
Rodents
RISK FACTORS
  • Travel to endemic area
  • Work in a medical or research lab
  • Work in building infested with rodent fleas or mites
DRUG LINK
Merck Manual: Rickettsialpox
REFERENCES FOR CASES/YEAR
1. (US) Initially described in New York City and then reported in eastern Europe, Korea, and South Africa; 34 cases identified in NYC from 2001-2002 and about 5 cases/year since then; IV drug users in Los Angeles and Baltimore had high seroprevalence for R. akari. Prevalence of disease is completely unknown. [PPID, p. 2358] Guestimate = 200 cases/yr;
2. (Global) 20 X US cases/yr;