Shigellosis symptoms

Definition

Shigellosis (or bacillary dysentery) is an acute infectious disease that affects the small intestine.

The infection is caused by bacteria belonging to the genus Shigella . These microorganisms are sensitive to the action of common disinfectants and detergents, but in the external environment they can present varying degrees of resistance.

Shigellosis is transmitted via the fecal-oral route, so the infection can occur with the ingestion of water and foods that come into contact with faecal material from infected individuals or convalescent carriers (in the same way as cholera or typhus). The disease can be contracted even after the use of contaminated tools. Furthermore, flies can act as passive vectors, as they mechanically transport germs from contaminated materials onto food and objects, thus favoring the spread of infection.

Shigellosis is endemic in many developing countries. Type 1 Shigella dysenteriae represents, in particular, a public health problem, as it is capable of causing a form of serious illness. In fact, this bacterium produces a toxin that causes massive watery diarrhea and, sometimes, a hemolytic-uremic syndrome. The Shigella dysenteriae type 1 also correlates to a high epidemic potential: the low infectious dose facilitates the transmission from one person to another and the infection confers a scarce or no immunity. In untreated cases, lethality can reach 10-20%.

Shigellosis is a disease that can occur with clinical pictures of varying severity.

Generally, the most severe forms affect infants and adults over the age of 50; moreover, people with concomitant states of malnutrition, dehydration and measles are particularly at risk.

Shigellosis begins after an incubation period of 1-4 days. The most frequent manifestation is diarrhea characterized by discharges of liquid stools, sometimes with visible blood, pus or mucus. This can be associated with abdominal cramps and unproductive tenesmus (painful spasm of the anal sphincter with urgent stimulation to defecation). These episodes are repeated with increasing gravity and frequency. Other common symptoms include fever, nausea and vomiting.

In most affected individuals, shigellosis resolves spontaneously within 7-10 days; however, serious complications can occur and healing can take up to 3-6 weeks. Due to severe tenesmus rectal prolapse and consequent fecal incontinence may occur. Sometimes, marked dehydration and severe electrolyte loss, seizures, intestinal perforation, haemolytic-uremic syndrome and circulatory collapse may develop. Death can occur within 12-24 hours.

The diagnosis is clinical and is confirmed by the coproculture, that is isolating the germ from the faeces, then subjected to serotyping (note: the diarrhea of the shigellosis is indistinguishable from that caused by other bacterial, viral and protozoan infections that stimulate the secretory activity of epithelial cells bowel.). The faeces culture also allows the determination of antimicrobial sensitivity.

The therapy is antibiotic and supportive, mainly rehydrating.

At the moment, there is no effective vaccine to prevent Shigella infection. Prevention is however possible by adopting preventive measures that are also valid for avoiding other diarrheal fecal-oral transmission infectious diseases, such as washing hands with soap before handling food, disposing of waste properly and consuming safe drinking water.