Epidemic typhus

Epidemic typhus

epidemic typhus– an acute infection characterized by a cyclic course, fever, roseolous-petechial rash and lesions of the nervous and cardiovascular systems. Etiology. The causative agent is the gram-negative bacterium Rickettsia prowazekii. Epidemiology. The source of infection is a sick person, the epidemic danger is starting from the last 2-3 days of the incubation period and up to 7-8 days after the normalization of body temperature. The causative agent is transmitted transmissively, the carriers are body lice, less often head lice. The gates of infection are minor skin lesions (usually scratching). A seasonal increase in the incidence in the winter-spring period is characteristic. Currently, the disease is recorded mainly in the developing countries of Africa, Asia, South and Central America. Pathogenesis. Rickettsia multiply in the vascular endothelium, causing a granulomatous inflammatory reaction involving the vascular wall and its segmental or circular necrosis. As the pathogen disseminates, vascular damage becomes generalized, which causes clinical manifestations: a maculopapular rash appears on the skin, disseminated thrombosis is noted in the vessels with the development of ischemia and necrotic changes in the perivascular tissues. Generalized damage to the endothelium leads to an increase in vascular permeability, the appearance of edema and hemorrhage with the development of shock; damage to endotheliocytes activates the coagulation system with the likely formation of DIC. The death of patients is caused by acute heart failure (the main cause), CNS lesions or circulatory disorders, also indirectly leading to heart failure.

Clinical picture

• • Incubation period -6-21 days (usually 12-14 days)
  • Characterized by an acute onset, an increase in body temperature up to 39-40 ° C, weakness, severe headache, loss of appetite. The severity of the manifestations progressively increases, the headache becomes unbearable, the patients are agitated (insomnia, irritability, hyperesthesia)
  • In severe forms, disorders of consciousness are possible.
  • When examining the sick, hyperemia of the skin of the face, neck, upper chest is noted. Sclera vessels injected (red eyes on a red face)
  • From day 3, Kudpu-Avtsyn spots are detected (purple-bluish spots on the transitional fold of the conjunctiva)
  • An early sign is Rosenberg’s enanthema in the form of petechiae on the mucous membrane of the soft palate and palatine uvula (detected in 90% of patients)
  • On 4-6 days, a characteristic petechial-roseolous rash is observed.
  • There are primary petechiae located on roseola; in severe forms, petechiae predominate, in mild forms and in Brill’s disease, the rash is mainly roseolous. The rash is profuse, localized on the trunk and extremities and very rarely – on the face, palms and soles.
  • Most patients have circulatory disorders (tachycardia, decreased blood pressure, muffled heart sounds, ECG changes)
  • Almost all patients with 4-6 days reveal an increase in the liver, and in 50-60% and an increase in the spleen
  • The duration of the disease depends on its severity.
  • In the absence of antibiotic therapy, fever in mild forms lasts within 1 week, in severe forms – 12-14 days.

Research methods

• • Microscopy of the pathogen in stained smears, Romanovsky-Giemsa, Castaneda and Macchiavelo stains are used (Zdrodovsky’s modification of PF can be used)
  • The Weil-Felix reaction is based on the probability of the serum of patients suffering from various rickettsiosis to agglutinate OX strains (especially OX, and OX2) Proteus vulgaris, AT to the causative agent of typhus cross-react only with bacteria of the OX,9 strain. The reaction is due to the structural similarity of surface Ag
  • Other serological reactions (RCC with Ag rickettsia Provaceca, microagglutination reaction, hemagglutination, etc.). WHO recommends an indirect immunofluorescence test. In diagnostic titers, AT begin to appear in the blood serum on days 4-7 of the disease. Differential Diagnosis
  • Meningitis
  • Measles
  • Rubella
  • Toxoplasmosis
  • Leptospirosis
  • Typhoid fever
  • Secondary syphilis
  • Infectious mononucleosis.

Treatment:. Specific chemotherapy begins immediately after the diagnosis is made (even preliminary after taking blood for research) and continues after a decrease in body temperature for at least 2 days.

• • Tetracycline (adults, children over 8 years old) orally at an initial dose of 25 mg / kg, then 25 mg / kg / day after 6-8 hours or doxycycline 100 mg every 12 hours (adults), 5 mg / kg (up to 200 mg / day) after 24 hours (children over 8 years old).
  • Chloramphenicol (levomycetin) for pregnant women, children under 8 years of age, and adults inside at the initial dose of 50 mg / kg, then 50 mg / kg / day after 6-8 hours.
  • In severe cases, tetracycline or chloramphenicol is administered intravenously.
  • Treatment of septic shock (see Shock), DIC (see Disseminated intravascular coagulation), acute renal failure (see Acute renal failure).

Complications

• • Thrombophlebitis
  • Endarteritis
  • TELA
  • Myocarditis.

Synonyms

• • Louse typhus
  • Murine typhus A75 Typhus Literature. 129:255-256