Generality
Shigella is a genus of non-motile, gram-negative, non-spore-forming, aerobic-facultative rod bacteria with low resistance to heat and environmental stress.
Like salmonellae and escherichia, shigellae belong to the Enterobacteriaceae family; it is therefore not surprising that these microorganisms have their ideal habitat in the human intestine and in that of primates.
Symptoms of the infection
For further information: Shigellosis Symptoms
Once in the intestine, a few Shigella cells (10-100) can cause an intestinal pathology known as shigellosis or bacillary dysentery, characterized by diarrhea, crampy abdominal pain, intense dehydration and anorectal tenesmus.
Occasionally, vomiting and high fever occur, especially in children under the age of 10, among whom the risk of convulsions is also greater (in this case a rapid medical intervention is required).
The invasion of the intestinal wall causes tissue lesions and alterations in electrolytic transport. Superficial necrosis, which can produce extensive ulcerations, causes the emission of faeces mixed with mucus and blood. In the mild forms, the epithelial lesions of the intestine undergo complete healing, while in the most serious the mucosa can remain marked by fibrotic scars with stenosis and the formation of multiple polyps. Dehydration, very dangerous in children, can be recognized for the " absence of tears in crying, dry lips and skin, and other signs such as dizziness, sunken eyes and dry diapers.
The incubation time can vary from ten hours to a week, but generally lasts a couple of days.
In immunosuppressed individuals, shigellosis can be fatal; despite this, the death rate in industrialized countries remains extremely low. The ingestion of even a rather small number of bacteria is sufficient to cause the disease, especially in children aged between two and four years (much more susceptible than adults). greater risk of remaining healthy carriers for a long time, children are also an "important source of" infection.
Infection
Human-to-human transmission of shigella occurs mainly through fecal contamination of food and water. For example, direct contact with feces during a diaper change - not followed by thorough hand washing - promotes the transmission of the disease from the infant to the child. "adult. Theoretically, shigellosis can also be contracted by swimming in water sources contaminated with sewage and sewage. Failure to clean hands after going to the toilet promotes disease transmission in communities, especially when it is followed by food handling. As a preventive measure, food must also be protected from dust and flies (possible vehicles of infection) and stored in the refrigerator to prevent bacterial multiplication. A significant epidemiological problem is represented by convalescents and healthy carriers, that is, from that part of population that despite being cured of the disease continues to eliminate the bacilli for months or even years.
Despite being a typically food-related disease, shigellosis also falls into the category of venereal diseases. Especially in groups with poor socio-economic conditions and among homosexual males, it can in fact cause sexually transmitted vaginitis and proctitis.
The clinical diagnosis must be confirmed by isolation of shigella in faeces. If a person is in good health, small infections can heal spontaneously without causing too many problems, especially if caused by Shigella sonnei. The symptomatology sustained by this species is in fact generally modest and less severe than that caused by Shigella dysenteriae. The latter causes a fairly severe clinical picture even in young adults and is particularly dangerous, and sometimes fatal, in children and the elderly.
Care and treatment
For further information: Medicines for the treatment of shighellosis
Shigellosis therapy is primarily based on generous rehydration of the fluids lost with diarrhea; in children the use of specific solutions enriched with electrolytes such as sodium, potassium and calcium, available in pharmacies, is indicated. In the impossibility, rehydration therapy can also be performed intravenously in the hospital setting. The use of antidiarrheal drugs, which can even aggravate the clinical picture, is contraindicated.
In the most serious cases it may be necessary to resort to a specific antibiotic treatment, indicated above all in the categories with the highest risk of complications. The emergence of antibiotic-resistant strains of shigella has led many doctors to reserve antibiotic therapy only for the treatment of the more severe forms.
