Epidemic (Louse-borne) Typhus

Epidemic typhus is an acute rickettsial disease. Rodents are the main reservoir; chigger mites transmit it to humans. Clinical: acute onset fever, rash, lymphadenopathy, hepatosplenomegaly, CNS symptoms; course 2-3 weeks. Recurrence months-years later = Brill-Zinsser disease.

Common Symptoms

Macule; shock; chest pain; fatigue; testing; hearing loss; arrhythmia; low fever; dizziness; chills; green urine

Causes and Pathogenesis

Etiology: R. prowazekii, intracellular in vascular endothelium/louse gut epithelium; attached to RBCs/platelets during rickettsemia. Coccobacillary, chained, pleomorphic in louse gut; 0.3-1 × 0.3-0.4 µm; Gram-negative. Contains protein/carbohydrate/lipid/phospholipid/DNA/RNA/enzymes/vitamins/endotoxin-like LPS. Heat/UV/disinfectant-sensitive (56°C/30 min); cold/dry-resistant (months in dried louse feces). Cross-reacts with Proteus OX19 (Weil-Felix). Group-specific soluble heat-stable antigen + type-specific heat-labile particulate antigen. Grows in yolk sac; guinea pig inoculation causes fever/vascular lesions without scrotal swelling (vs R. mooseri). Toxin lyses RBCs and kills small animals in 6-24 h. Pathogenesis: vascular lesions + toxemia + immune reactions. Rickettsiae enter skin/mucosa, multiply locally → rickettsemia → new foci in small vessels; second-week immune vasculitis. Pathology: proliferative/thrombosing/necrotizing vasculitis with "typhus nodules" (microgranulomas) throughout skin/heart/testis/brain/meninges/kidney/adrenal/liver/alveoli; CNS (cortex/cerebellum/medulla/basal ganglia/pons/spinal cord) dominates; interstitial myocarditis/nephritis/hepatic necrosis/splenomegaly.

Treatment

Drug therapy, supportive therapy

Preventive Measures

Prevention focuses on delousing and mass hygiene. (1) Rodent control (zinc phosphide/anticoagulants). (2) Avoid chigger exposure; tuck clothing; insect repellent (dibutyl phthalate/benzyl benzoate). (3) No human vaccine yet; 56 kDa outer-membrane protein antigen is immunogenic—vaccine under study.

Department to Visit

It is recommended to visit the Infectious Diseases department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.