Controlling Endemic Typhoid Fever

Improvements in sanitation and the provision of clean drinking water led to the elimination of typhoid fever from developed countries in the beginning of the 20th century. However, Salmonella typhi and paratyphi remain a major source of morbidity and mortality in many developing countries today. The dynamics of typhoid transmission are poorly understood. Two vaccines against typhoid are currently licensed and used worldwide, but there is conflicting evidence as to whether these vaccines are expected to confer a potential herd immunity benefit for the population. Using mathematical models fit to hospital surveillance data, we are comparing the transmission dynamics of typhoid in present-day endemic settings, including Kathmandu, Nepal; Vellore, India; and Ho Chi Minh City, Viet Nam. We will use these models to evaluate the feasibility and impact of different methods of typhoid control, including vaccination, improved treatment strategies, and investment in clean water and sanitation.