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Rocky Mountain Spotted Fever. Pat Barrett Morning Report July 2, 2010. Rickettsia rickettsii (facts you probably know). Tick borne, though 1/3 to 1/2 do not recall a tick bite Dermacentor variabilis tick Incidence 15/100,000 persons at the most endemic areas - PowerPoint PPT Presentation
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Pat BarrettMorning Report
July 2, 2010
Tick borne, though 1/3 to 1/2 do not recall a tick bite
Dermacentor variabilis tick
Incidence 15/100,000 persons at the most endemic areas
1-3% ticks infected in endemic areas
MMWR: 2006: 55RR04: 1
Gram negative intracellular Virulence depends on the status of
the vector Trophic for endothelial cells Transits rapidly by activating actin
within host’s cells No exotoxins, will cause necrosis,
lymphohistiocytic vasculitis
CDC /epidemiology
Vector # of Cases 2009
Therapy
RMSF American Dog Tick (D. variabilis)
259 Doxy, 2nd line Chloramphenicol
Ehrlichiosis Lone Star Tick (A. americanum)
31 Doxy, 2nd line Chloramphenicolor Rifampin
Lyme White TaiIed Dear Tick (I scapularis)
65 (only 2 confirmed in-state inoculations)
Doxy, amox, or cefuroxime
Anaplasmosis White TaiIed Dear Tick (I scapularis)
Doxy, 2nd line Chloramphenicolor Rifampin
STARI Lone Star Tick (A. americanum)
Doxy, 2nd line amox
Usually develop 5-7 days after tick exposure
Fever, headache, myalgia, arthralgia, nausea, vomiting
Spotless RMSF occurs approx 10% of the time
Typically at 5-7 days
Begins on wrists, ankles, palms and soles, then spreads centripetally
Often macularpapular then petechial
Rarely pruritic
Case Series from Duke (1) 61% male 66% African American 53% mortality in the case series 22.9% mortality in separate case
series (2) where treatment was delayed past 5 days
6.5% mortality if treated w/in 5 days
1: Clin Infect Dis 1992: 15:4392: Clin Infect Dis 1995: 20:1118
Clinical impression followed by acute and convalescent sera
Typically the latex agglutination has the fastest turn around time
IFA test for IgG and IgM, felt to be the standard, used by CDC.
False positives w/ other rickettsial exposures
PCR not widely available Also hyponat, elevated
transaminases, prolonged PT, aPTT
Gold Standard: 4 fold increase from acute to convalescent, convalescent IFA > 1:64, isolation of Rickettsiae, fluorescent ab of specimen from bx or autopsy
Indirect hemagglutination 94% sens Indirect fluorescent antibody 96%
sens Latex agglutination 71% sensAm J Trop Med Hyg: 1986: 35: 840
Doxycycline 7 days, 10-14 in severe cases
2nd Line Chloramphenicol No preventive therapy recommended
for tick bites w/o illness – shown to delay symptom onset but not prevent infection.
J Clin Microbiol 1978;8:102
Ticks are awful RMSF and Ehrlichia should be
considered during any FUO work-up while a resident at UNC
There is some variability in when serology is positive
Rashless and rashalittle RMSF does exist
The benefits of not treating empirically must be carefully weighed against the risks
NC DHHS: http://www.epi.state.nc.us/epi/gcdc/pdf/cdtable2009.pdf CDC/epidemiology:
http://www.cdc.gov/ncidod/dvrd/rmsf/epidemiology.htm Chapman, AS et. MMWR: 2006: 55RR04: 1 Up To Date: RMSF Sexton, DJ, et al. Clin Infect Dis 1992:
15:439 Kirkland, KB, et al. Clin Infect Dis 1995:
20:1118 Kaplan, JB, et al. Am J Trop Med Hyg:
1986: 35: 840 Kenyon RH, Williams RG, Oster CN,
Pedersen CE Jr. Prophylactic treatment of Rocky Mountain spotted fever. J Clin Microbiol 1978;8:102--4.