Gastroenteritis

Inflammation of the stomach and intestines, usually causing sudden upsets that last for two or three days. Dysentery, typhoid fever, cholera, food poisoning, and travellers’diarrhoea are all forms of gastroenteritis.

Gastroenteritis may be caused by a variety of bacteria, bacterial toxins, viruses, and other organisms in food or water. There are also a number of non-infectious causes, such as food intolerance and certain irritant drugs.

The usual symptoms are appetite loss, nausea, vomiting, cramps, and diarrhoea. Their onset and severity depend on the cause; symptoms may be mild, or may be so severe that dehydration, shock, and collapse occur. Mild cases usually require rest and rehydration therapy only.

For severe illness, treatment in hospital may be necessary, with fluids given by intravenous infusion. Antibiotic drugs may be given for some bacterial infections, but others need no specific treatment.

More about gastrointestinal infections

Gastrointestinal infections, especially diarrhoea, are responsible for substantial morbidity, mortality, and socioeconomic penalties worldwide. In poor countries, the greatest burden of disease is borne by infants and young children, although older people and immunocompromised patients are also at great risk of severe and complicated disease. Poor sanitation, inadequate water supplies, and globalization of food marketing increase the risk of large epidemics of food- and water-borne outbreaks of gastrointestinal disease.

Clinical syndromes

Enteric pathogens can cause intestinal disease by means of enterotoxins, adherence to gut mucosa, or invasion of enterocytes. Acute diarrhoea can be caused by pathogens ranging from toxin-producing strains of Escherichia coli to rotavirus and Giardia spp. Gastrointestinal pathogens usually cause three principal syndromes: noninflammatory diarrhoea, inflammatory diarrhoea, and systemic disease. Noninflammatory diarrhoea targets the small intestine and inflammatory diarrhoea the colon, the site of infection influencing the clinical and diagnostic features. Organisms affecting the small intestine tend to produce watery, potentially dehydrating diarrhoea, whereas those infecting the large intestine cause bloody, mucoid diarrhoea.

Patients who do not have high fever (>38.5°C), systemic illness, tenesmus, bloody diarrhoea, a prolonged course (>2 weeks), or dehydration require neither investigation nor treatment. Investigation is required in patients with any of these features, with faecal specimens subjected to microscopy (ova and parasites), direct electron microscopy (viruses), bacteriological and viral culture, and identification of microbial antigens (viruses, bacteria, parasites, or toxins). A specific laboratory diagnosis is useful epidemiologically and therapeutically, especially for invasive pathogens and diarrhoea in high-risk patients such as the very young, elderly, or immunocompromised.

Treatment and prevention

Oral rehydration therapy is the priority in management of children and adults with mild to moderate diarrhoea as long as vomiting is not a major feature, and it can also follow initial parenteral rehydration in severely dehydrated patients. Empirical antimicrobial therapy is necessary in more severe cases, pending the results of stool and blood cultures. Antibiotic treatment benefits cholera, giardiasis, cyclosporiasis, shigellosis, E. coli diarrhoea in infants, symptomatic traveller’s diarrhoea, Clostridium difficile diarrhoea, and typhoid. Fluoroquinolones were the ideal choice for empirical therapy because of their broad spectrum of activity against common gastrointestinal bacterial pathogens, but increasing resistance and clinical treatment failures in South East Asia and the Indian subcontinent have forced a switch to azithromycin for acute traveller’s diarrhoea and other forms of diarrhoea in this region. Antimotility drugs are useful in controlling moderate to severe diarrhoea.

Strict attention to food and water precautions and hand washing helps reduce the risk of gastrointestinal infections in poor countries. Although immunization offers an ideal way to prevent certain bacterial and viral diseases, it has not yet proved successful for combating many gastrointestinal pathogens, with the notable exception of rotavirus