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Clinical Characteristics

The incubation period of shigellosis varies from 24 hours to a week. The onset may be sudden or insidious; it commonly presents as a simple diarrhea but may be quite varied in its severity, especially in Shiga infection where an acute fulminating attack may occur. The chief clinical symptoms are manifestations of the colonic inflammation, namely gripping abdominal pain, tenesmus, and frequent passage of loose, scanty, mucosanguinous stools; there is often dysuria. There may be a high fever to 104F (40C) or no fever at all. Vomiting may be present from the beginning or may be totally absent. Rigidity of the recti muscles may make palpation of the abdomen difficult early in the disease. Later, the abdomen may become lax and the spastic sigmoid colon may be palpable. For the first day or two, there is often a leukocytosis of 15,000 to 30,000 WBC per cm, subsiding to normal by the fourth day.

The stools may vary greatly in number and character: at first fecal and diarrheic, their frequency may become so numerous that the poor patient may be "glued" to the toilet. Initially, the stools are scanty and odorless and contain viscid blood-stained mucus, resembling red currant jelly. Later, they are less bloody and more purulent.

Proctoscopy reveals a swollen, diffusely inflamed rectal mucosa, often covered with mucus and pus. Underlying this exudate is a granular mucous membrane which freely oozes blood. There may be shallow ulcers, irregular in size and shape and covered with pus.

Cases of bacillary dysentery may be classified as follows:

1. Mild or Catarrhal Dysentery

The patient has mild diarrhea with four or five stools the first day, initially bilious and loose, later becoming more frequent, less formed and more mucoid. There is some tenesmus but little or no fever and the attack may subside in a week. Most of these mild infections are caused by Flexner or Sonne and Schmitz bacilli.

2. Acute Dysentery

The onset is abrupt and severe dysentery may develop within a few hours. The stools are well formed at first, but marked tenesmus and the desire to evacuate develop rapidly, with passage of little except blood-stained mucus. There is often a high fever which gradually subsides. A toxic flush of the face and slight delirium, thirst, anorexia, a coated tongue, and dysuria are present. After a week, the symptoms subside and the illness either ends as abruptly as it began or passes into a subacute or chronic phase.

3. Fulminating Dysentery

In severe Shiga infections the onset of illness is generally sudden, with chills, rigor, headache, vomiting, and a fever of 100-104F (38-40C). The tongue is thickly coated and the abdomen sunken and acutely tender. The stools rapidly become dysenteric, being liquid, foul-smelling and numerous. Within 2-7 days, peripheral vascular failure develops and the patient succumbs. A rare choleric form may occur with rapid onset and vomiting.

Young children, especially in temperate zones, who acquire Shiga or Flexner dysentery may develop acute and rapidly fatal symptoms, with convulsions, meningismus, altered consciousness, toxic fever, and thrombocytopenia occurring before intestinal symptoms can develop.

4. Relapsing Dysentery

In some patients with bacillary dysentery, the initial illness may subside but the symptoms of dysentery persist and recur.

5. Chronic Dysentery

In many patients with acute dysentery, the feces do not return to normal for many months or years after the initial symptoms have subsided. These unformed stools always contain some mucus, pus, or blood. The dysentery may relapse and reappear at the slightest provocation, with unexplained attacks of diarrhea.

A granular proctitis involving the distal 3 inches of the rectum, accompanied by the passage of blood and mucus, may at times be a sequel to Shiga infections.

Complications of shigellosis include arthritis and iritis (Reiter's syndrome), parotitis, polyneuritis, intestinal hemorrhage, glomerulonephritis and renal failure (hemolytic-uremic syndrome), with peripheral circulatory failure occurring particularly in Shiga infections. Children may suffer from intussusception. Stenosis of the colon may result after the acute attacks. It is estimated that about 10% of patients will become convalescent carriers, (for a period usually lasting less than a month in well-nourished individuals) , or chronic carriers, who continue to pass blood, mucus, and bacilli in their stools. Carriers of Flexner bacilli are more common than Shiga carriers. Carriers of either organism are the probable source of most epidemics.

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Copyright: Palmer and Reeder by Springer


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