Epidemiology and General Characteristics
Shigellosis incidence is reported year-round, although the infection exhibits a pronounced summer-autumn seasonality with a characteristic peak in July and August.
The primary risk group consists of children aged 3 to 10 years, especially those regularly attending organized childcare facilities. Immunity following a dysentery episode is extremely short-lived, which does not rule out the possibility of reinfection.
A fundamental feature of the disease is that the patient's condition—especially in the first days—is driven not by dehydration (fluid loss), but by severe neurotoxicity.
Classic Clinical Presentation
The incubation period of the infection ranges from 1 to 7 days. In children over one year of age, the disease always manifests acutely and is characterized by the simultaneous development of intoxication syndrome and local intestinal involvement.
- Intoxication and neurotoxicity syndrome. The disease begins with a sharp rise in body temperature to febrile or even hectical values (38.5–40.0 °C). The child becomes lethargic, weakness increases, and chills and headache appear. Against the background of pronounced hyperthermia, severe neurological disorders may develop, including impaired consciousness, delirium, seizure syndrome, and meningeal signs.
- Dyspeptic syndrome. Appetite drops sharply up to complete anorexia. Vomiting is not a leading or mandatory clinical sign: it is recorded in only half of patients, occurs rarely (1–2 times a day), and is mainly troublesome in the very first days of the illness.
- Distal colitis syndrome. This is the core symptom complex of shigellosis, reflecting damage to the colonic mucosa. Patients complain of agonizing, pulling, and cramping pain localized in the left iliac fossa. Pain attacks are clearly linked to the act of defecation, occurring immediately before it. During abdominal palpation, the physician determines spasm and marked tenderness of the sigmoid colon.
Local symptoms are complemented by the development of sphinkteritis and pathological laxity of the anal opening. Patients are exhausted by tenesmus—false, extremely painful urges to defecate. Stool characteristics undergo specific changes: excrement becomes scant, liquid, and loses its fecal character. Turbid mucus and streaks of blood are found in it. In pediatrics, this pathognomonic sign is known as the "rectal spit".
Age-Specific Features in Children Under 1 Year
In infants under one year of age, the clinical picture of shigellosis differs significantly from the classic course. The disease often debuts subacutely or gradually, and fever rarely reaches hectical levels, remaining moderate.
The clinical picture is dominated by the dyspeptic form. Distal colitis syndrome, typical for older children, is practically absent in infants. Stools are usually pasty or liquid in consistency, while specific pathological impurities (blood and turbid mucus) in the stool are frequently entirely absent.
Despite the masked local manifestations, shigellosis in infants can be extremely severe. The life threat at this age is caused not by colonic mucosal inflammation, but by severe systemic disorders: hemodynamic instability, as well as water-electrolyte and protein metabolism disturbances.
Impact of Pathogen Species on Disease Course
The duration and severity of clinical manifestations of shigellosis in children over 1 year largely depend on the specific species of the causative bacterium.
- Sonne dysentery (Shigella sonnei). It is characterized by a relatively mild course. Vomiting in such patients lasts no more than one day, and the febrile period is limited to 1–2 days. Diarrheal syndrome resolves completely in less than a week, and symptoms of hemocolitis (blood in the stool) persist for 1 to 3 days.
- Flexner dysentery (Shigella flexneri). It proceeds significantly more severely and over a longer duration. This form is characterized by the most pronounced distal colitis syndrome with very frequent defecation. In addition, patients exhibit severe hemorrhagic syndrome, creating a high risk of developing dangerous intestinal bleeding.
The "3 C's" rule for distal colitis syndrome: Cramping pain, Sigmoid colon spasm, Scant stool (rectal spit).
Class and exam questions
What is the main cause of severe condition in shigellosis?
Unlike many intestinal infections, the severity of dysentery is caused by marked neurotoxicity (fever up to 40 °C, seizures, delirium) rather than fluid loss.
What does typical stool look like in the classic course of the disease?
Stool becomes scant, liquid, loses its fecal character, and consists of turbid mucus with streaks of blood. This symptom is called the "rectal spit".
How does the course of infection differ in infants under 1 year of age?
In infants, the dyspeptic form with a gradual onset predominates. Distal colitis syndrome is not pronounced, and blood and mucus are often absent in the stool. The severity of the condition is associated with systemic metabolic and hemodynamic disorders.
What else to study on this topic
- Mechanisms of neurotoxicity development in gram-negative infections
- Differential diagnosis of the dyspeptic form of shigellosis in infants
- Pathogenesis of hemorrhagic syndrome and bleeding risk in Shigella flexneri infection
- Principles of water-electrolyte and protein metabolism correction in infants
- Prevention of shigellosis outbreaks in organized childcare facilities
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