Pathogenesis as the basis of the clinical picture
The key to understanding the symptoms of typhus lies in its pathogenesis. The pathogen causes partial or complete obliteration of the microvasculature by thrombi, followed by vascular destruction. In tissues suffering from ischemia, specific typhus granulomas are formed — Popov-Fraenkel-Davydovsky nodules.
The main target organs where granulomas accumulate are the brain, skin, myocardium, and adrenal glands. Their dysfunction determines the patient's presentation. For instance, coagulation necrosis of the adrenal cortex leads to a decrease in adrenaline production, which causes one of the most constant symptoms — persistent arterial hypotension.
Initial (pre-exanthematous) period
After a short prodrome, the disease starts acutely. Within 2–3 days, the fever reaches 38–39°C. Severe intoxication builds up, manifesting as persistent, agonizing headache, insomnia, and hyperesthesia (intolerance to light, sound, and touch).
Bright specific signs are detected upon physical examination as early as the first days:
- «Hood» sign — marked hyperthermia/hyperemia of the skin of the face, neck, and upper chest (a consequence of granulomatosis of the cervical sympathetic ganglia).
- «Rabbit eyes» sign — injection of scleral vessels and glistening conjunctivae.
- Adesman's sign — tenderness upon palpation of the neck over the projection of the sympathetic ganglia.
- Rosenberg-Vinokurogram-Lendorf sign — on days 2–3, an enanthem consisting of 5–6 small petechiae appears on the hyperemic mucosa of the soft palate.
- Chiari-Avtsyn sign — enanthem on the conjunctival folds.
There are no natural skin eruptions yet, but the vessels are already damaged. This is confirmed by positive provocative capillary fragility tests (the tourniquet test and the pinch sign).
Period of height
Begins on days 4–5. On the eve of the rash appearance, a temperature «dip» is often recorded — a drop in temperature by 1.5–2°C, synchronous with a sharp drop in blood pressure. Immediately after this, an abundant roseolous-petechial exanthem erupts.
It is localized on the trunk and flexor surfaces of the extremities (the face and soles are rarely affected). Roseolae disappear without a trace within 4–5 days, while petechiae go through the stages of «bruise evolution» over 10–13 days.
At the height of the disease, acute meningoencephalitis progresses:
- Meningeal signs appear (Kernig's and Brudzinski's signs).
- Cranial nerve nuclei are affected. A crucial marker is Govorov-Godelier sign: due to hypoglossal nerve involvement, the patient cannot stick their tongue out past the teeth, and the movements are jerky.
- In the mental sphere, a shift of phases is observed: at night — restlessness, motor agitation, and talkativeness; during the day — lethargy.
- Against the background of high fever, typhoid status may develop (the patient is sluggish and unresponsive to information).
- Paradoxical urinary retention (ischuria paradoxa) occurs — the inability to urinate with a full bladder due to discoordination of the sphincter, detrusor, and inhibition in the cerebral cortex.
Convalescence and severity of the course
The recovery period begins with a decrease in temperature via accelerated lysis (over 2–3 days). Symptoms gradually subside, but post-infectious asthenia (weakness, tearfulness, memory impairment) persists for a long time. The pathogen can persist in the endothelium for life; when immunity drops, a relapse occurs — Brill-Zinsser disease.
In 70% of cases, typhus runs a moderately severe course. However, extreme variants also exist:
- Mild course (more common in young people) is characterized by a fever up to 38°C, mild neurological manifestations without typhoid status, and a predominance of roseolae.
- Severe course is accompanied by hyperpyrexia (41–42°C), a drop in systolic BP below 80 mmHg, a pulse up to 140 beats per minute, and the development of a dream-like typhus delirium with terrifying hallucinations and escape attempts.
Briefly: answers to topical questions
What conditions must epidemic typhus be differentiated from in the initial period?
In the initial (pre-exanthematous) period, epidemic typhus must be differentiated from other acute infectious diseases. The differential diagnosis includes:
- Influenza — requires exclusion due to a similar onset with prominent intoxication syndrome;
- Meningococcal infection — differentiated from its generalized forms;
- Hemorrhagic fevers;
- Leptospirosis.
What laboratory methods are used to confirm the diagnosis of epidemic typhus?
To confirm the diagnosis of epidemic typhus, general clinical, serological, immunological, and molecular genetic methods are used.
- Complete blood count — characterized by leukocytosis, thrombocytopenia, neutrophilia with a band shift, and an increased ESR;
- Serological studies — detection of antibodies in dynamics in paired sera using the complement fixation test (CFT) and indirect hemagglutination assay (IHA) with Rickettsia prowazekii antigens;
- Immunological methods — detection of rickettsial antigens using IFA and ELISA;
- Molecular genetic methods — polymerase chain reaction (PCR) is used.
Govorov-Godelier sign is easy to remember as the «stumbling tongue sign»: due to hypoglossal nerve damage, the tongue stumbles against the teeth and trembles when protruded.
Class and exam questions
Why do patients develop the «hood» sign?
It develops due to the formation of granulomas in the upper and middle cervical sympathetic ganglia. This leads to persistent vasodilation of the vessels of the face, neck, and upper trunk.
What is a temperature «dip»?
This is a short-term drop in body temperature by 1.5–2°C, which usually occurs on the 4th day of the disease right before the appearance of the exanthem. It is accompanied by a simultaneous drop in blood pressure.
What is the mechanism of development of paradoxical ischuria in typhus?
It occurs due to irritation of the sympathetic nervous system (the urethral sphincter goes into spasm while the bladder wall relaxes) combined with inhibitory processes in the cerebral cortex, resulting in a loss of «voluntary control» over urination.
What else to study on this topic
- Pathomorphological stages of vasculitis development in typhus
- The mechanism of formation of the Popov-Fraenkel-Davydovsky granuloma
- Brill-Zinsser disease as a late relapse of infection
- Clinical characteristics of typhus delirium
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