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Typhoid fever : Background and Transmission.
Typhoid fever, also known as enteric fever, is a potentially fatal multisystemic illness caused primarily by Salmonella typhi. The protean manifestations of typhoid fever make this disease a true diagnostic challenge. The classic presentation includes fever, malaise, diffuse abdominal pain, and constipation. Untreated, typhoid fever is a grueling illness that may progress to delirium, obtundation, intestinal hemorrhage, bowel perforation, and death within one month of onset. Survivors may be left with long-term or permanent neuropsychiatric complications.
S typhi has been a major human pathogen for thousands of years, thriving in conditions of poor sanitation, crowding, and social chaos. It may have responsible for the Great Plague of Athens at the end of the Pelopennesian War. The name S typhi is derived from the ancient Greek typhos, an ethereal smoke or cloud that was believed to cause disease and madness. In the advanced stages of typhoid fever, the patient's level of consciousness is truly clouded. Although antibiotics have markedly reduced the frequency of typhoid fever in the developed world, it remains endemic in developing countries.
S typhi has no nonhuman vectors. The following are modes of transmission:
- Oral transmission via food or beverages handled by an individual who chronically sheds the bacteria through stool or, less commonly, urine
- Hand-to-mouth transmission after using a contaminated toilet and neglecting hand hygiene
- Oral transmission via sewage-contaminated water or shellfish (especially in the developing world)
An inoculum as small as 100,000 organisms causes infection in more than 50% of healthy volunteers.