Chapter 3: Rocky Mountain Spotted Fever

*Typhus fever, rickettsiosis

Rickettsia rickettsii

*gram negative rod
*obligate intracellular parasite
*intracelluar motility utlizing host cytoskeleton
*small 0.2 x 0.5 micro meters to 0.3 x 2.0 micro meters

Reservoir: ticks and other animals (rodents)
Portal of entry: epidermis
Mode of transmission: arthropod vector (wood or dog) tick bite

*5-14 days (on average a week)

*bacteria multiplies at site of tick bite
*bacteria invade endothelial
cells linning blood vessels
*bacteria spread leads to systemic inflammation and tissue damage

*rash (maculopapular) in 85-90% of people
> happens 2-5 dys after fever
>flate red lesions (non itchy) ussuallly smaller than 1 cm diameter
*Myalgia (muscle pain)
*damage at site of tick bite
*flu symptoms (fever, headache, loss of appetite, nausea, vomiting, stomach pain)

*starts at wrists and ankles

*tissue necrosis (digit and limb loss, hearing loss, paralsis, mental disability, kidney failure, heart failure)
*death (0.5 % cases treated) (20-80% untreated)

*5 x more likely in young children

*avoid tick invested area
*treat areas with insecticides
*wear protective clothing
*treat clothing with 0.5% permethrin
*bug repellents (20% DEET)

*Tetracycline (doxycycline)
*Chlorampheniocol