Gastrointestinal infections

Abstract

Gastrointestinal infections, especially diarrhoea and vomiting, are responsible for substantial morbidity, mortality, and socioeconomic penalties worldwide. Poor sanitation, inadequate water supplies, and globalization of food production, processing, and retailing increase the risk of large epidemics of food- and waterborne outbreaks of gastrointestinal disease. Acute diarrhoea can be caused by a range of pathogens. Gastrointestinal pathogens usually cause three principal syndromes: acute watery diarrhoea, acute bloody diarrhoea (inflammatory diarrhoea or dysentery), and persistent diarrhoea. They can also cause systemic disease. 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 examined by culture (bacterial pathogens and some protozoa), microscopy (ova, cysts, and parasites), immunoassays (some protozoa and viruses), and molecular methods, usually polymerase chain reaction (PCR) or reverse transcriptase PCR (bacterial toxin genes and viruses). A specific laboratory diagnosis is useful epidemiologically and therapeutically. Oral rehydration therapy is the priority for patients with mild to moderate diarrhoea as long as vomiting is not a major feature. Antimicrobial therapy is not recommended or usually required for uncomplicated diarrhoea, but antibiotic treatment is beneficial for cholera, giardiasis, cyclosporiasis, shigellosis, symptomatic traveller’s diarrhoea, Clostridium difficile diarrhoea, and typhoid. Antimotility drugs are useful in controlling moderate to severe diarrhoea in adults but they are not generally recommended for infants and young children under the age of 4 years. Strict attention to food and water precautions and hand washing helps reduce the risk of gastrointestinal infections. Immunization has not yet proved successful for combating many gastrointestinal pathogens, with the notable exception of rotavirus.