HIV /AIDS

HIV /AIDS is clearly associated with an increased risk of nontyphoidal Salmonella infection; however, the data and opinions in the literature as to whether this is true for S typhi infection are conflicting। If an association exists, it is probably minor.
Other risk factors for clinical S typhi infection include various genetic polymorphisms. These risk factors often also predispose to other intracellular pathogens. For instance, PARK2 and PACGR code for a protein aggregate that is essential for breaking down the bacterial signaling molecules that dampen the macrophage response. Polymorphisms in their shared regulatory region are found disproportionately in persons infected with Mycobacterium leprae and S typhi।
Environmental and behavioral risk factors that are independently associated with typhoid fever include eating food from street vendors, living in the same household with someone who has new case of typhoid fever, washing the hands inadequately, sharing food from the same plate, drinking unpurified water, and living in a household that does not have a toilet.As the middle class in south Asia grows, some hospitals there are seeing a large number of typhoid fever cases among relatively well-off university students who live in group households with poor hygeine।
Mortality/Morbidity
With prompt and appropriate antibiotic therapy, typhoid fever is typically a short-term febrile illness with a negligible risk of mortality। Untreated typhoid fever is a life-threatening illness of several weeks' duration with long-term morbidity. The case fatality rate in the United States in the pre-antibiotic era was 9-13%.
Race
Typhoid fever has no racial predilection.
Sex
Typhoid fever has no sexual predilection.
Age
Most documented typhoid fever cases involve school-aged children and young adults. However, the true incidence among very young children and infants is thought to be higher. The presentations in these age groups may be atypical, ranging from a mild febrile illness to severe convulsions, and the S typhi infection may go unrecognized. This may account for conflicting reports in the literature that this group has either a very high or a very low rate of morbidity and mortality.