Rickettsioses

Rickettsia – obligate intracellular parasites, they belong more to bacteria.

Typhoid fever (typhus exanthemicus)

 * originator: Rickettsia prowazekii (described by prof. Prowazek, a Czech-borne)
 * symptoms: high fever, headaches and maculopapular rash
 * if the patient is reinfected, the symptoms are less sever – Brill-Zinsser disease
 * source: Blood of the infected person
 * transmission: body louse, mostly through it's bites, which itch; rickettsia are in their feces, penetrate bites or through excoriations; it can also be infected by inhaling dust with this dung
 * incubation period: 10–14 days

Patogenesis

 * the bacteria multiplies in endothelium, which then proliferates and microthrombus formation occurs
 * perivascular infiltration neutrophils, macrofages and lymfocytes (spot nodule)
 * it mainly affects the CNS, myocard and skin

Clinical picture

 * sudden fever, chills and severe headaches
 * tachycardia, hypotension, hearing loss, sphotophobia and dry cough
 * pharyngitis and meningeal syndrome
 * 4.–7. day the exanthema occurs, which may disappear, but more often hemorrhages, resulting in dark brown buds (first on the chest, omitting the face, palms and soles)
 * after the appearance of the rash, deterioration occurs - stupor, delirium (the patient doesn't want to lie down and often tries to escape from his bed), urinary and stool incontinence
 * 9.–19. day may end in death, otherwise the condition will improve within 14 days
 * KO: leukopenia, aneozinophilia

Complications

 * bronchopneumonia, otitis media, purulent parotitis, furunculosis, trombosis

Diagnosis

 * epidemiological situation + clinical picture + Ig
 * immunity remains after infection, but the infection often persists latently in humans and later manifests itself as Brill-Zinsser disease if the patient is weakened

Prognosis

 * before the era of ATB mortality was 20–40% (high mortality was, for example, after the outbreak of the epidemic in the Terezín concentration camp ), with a timely administration of ATB the mortality radically fell to 1 %
 * cured does not leave consequences, in children the course is milder

Therapy

 * chloramfenikol, tetracyclines

Rattle (endemic typhus)

 * originator: Rickettsia typhi
 * reservoir: rats
 * transmission: flea
 * typically an illness of people employed in warehouses and ports

Clinical course

 * like a milder case of typhoid fever, complications occur rarely

Rocky mountain spotted fever

 * originator: Rickettsia rickettsii
 * reservoir: vertebrates
 * carrier: Tick
 * 4–8 days after tick bite, general symptoms are visible, maculopapular efflorescence on the wrists is aparent
 * the course is often severe, vascular system involvement, lethality 5%

African tick fever

 * in the Mediterranean
 * originator: Rickettsia conori
 * transmission: ticks parasitizing on dogs (often a black spot at the site of the tick's bite)

Rickettsian smallpox

 * pathogenic agent: Rickettsia akari
 * transmission: mites
 * sources: rodents
 * general symptoms with maculopapular rash

Q fever

 * originator: Coxiella burnetii (original name Rickettsia burneti); when it was discovered, its originator was not known, so Q (query)
 * acute febrile illness, sudden onset, headaches, atypical pneumonia
 * sources: rodents, birds
 * transmission: Ticks, to another animal (sheep, goats); sick animals have rickettsiae in milk, urine, airway secretion; transmission to humans takes place either through direct contact with animals or during the processing of products from infected animals

Clinical picture

 * sudden onset with a fever and headaches
 * fifth day: dry cough, chest pain, physical findings mostly inconclusive; atypical pneumonia perihiliously visible on X -ray (can also resemble carcinoma in older patients)
 * for further details: Q fever

Related articles

 * Typhoid fever
 * Bacterial gastroenteritis