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, macrophages 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

Typical typhoid rash

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

A: Normal chest X-ray, B: Q fever caused atypical pneumonia

• 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

Links

Related articles

• Typhoid fever
• Bacterial gastroenteritis

Sources

• BENEŠ, Jiří. Studijní materiály [online]. [cit. 2009]. <http://jirben.wz.cz>.

Used literature

• HAVLÍK, Jiří, et al. Infektologie. 2. edition. Praha : Avicenum, 1990. 393 pp. ISBN 80-201-0062-8.

• LOBOVSKÁ, Alena. Infekční nemoci. 1. edition. Praha : Karolinum, 2001. vol. 263. ISBN 80-246-0116-8.