Typhoid fever is an acute, often severe illness caused by S. typhosa and characterized by fever, headache, apathy, cough, prostration, splenomegaly, maculopapular rash, and leukopenia. Typhoid fever is the classic example of enteric fever caused by salmonellae.
Incidence and Prevalence.
Typhoid fever is a disease of major importance in areas of the world that have not attained high standards of public health. A progressive decrease in incidence of typhoid fever has occurred in the United States since 1900, but sporadic c&ses and limited outbreaks continue to occur. About 400 to 500 cases per year have been reported in recent years. Some of these infections were acquired in other areas of the world, but many were acquired in the United States from food contaminated by chronic typhoid carriers. In the United States more than 3000 chronic typhoid carriers are under supervision by health departments, but the actual number of chronic carriers is probably considerably higher. Typhoid fever will continue to occur on a limited scale in countries with high standards of public health because of the frequency of typhoid in other areas of the world, the magnitude of intercontinental travel, and the existence of reservoirs of chronic carriers.
The ultimate source of infection with S. typhosa is a patient with typhoid fever or a typhoid carrier. Patients with typhoid fever excrete large numbers of S. typhosa in feces or urine, and viable bacilli may also be present in vomitus, respiratory secretions, or pus. Chronic enteric carriers, the most important source of infection, often excrete 106 or more viable bacilli per gram of feces. The typhoid bacillus can survive for weeks in water, ice, dust, and dried sewage. Water containing typhoid bacilli has been responsible for many outbreaks in the past; it may be contaminated directly by excreta containing S. typhosa or by excreta washed down from remote sites by rain or introduced by faulty sanitation.