Modeling the Potential for Vaccination to Diminish the Burden of Invasive Nontyphoidal Salmonella Disease in Young Children in Mali, West Africa

A surveillance program at Gabriel Touré Hospital in Mali observed a high burden of invasive disease caused by non-typhoidal Salmonella (iNTS). This surveillance program was originally instituted to measure the amount of invasive disease (e.g., septicemia, meningitis) caused by two bacteria that invade the respiratory tract: Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (pneumococcus). While documenting the burden of these pathogens, the surveillance program also found that serotypes of iNTS, mainly Salmonella Typhimurium and Salmonella Enteritidis, were common causes of severe invasive disease. As the number of cases of Hib and pneumococcus markedly decreased following the introduction of relevant vaccines, the relative threat of iNTS increased. Little is known about the reservoir of iNTS, whether it resides in humans, animals, or the environment, or how it is spread to susceptible children. Without this knowledge, it is not possible to employ certain disease control methods useful in interrupting the transmission of other pathogens. Therefore, vaccination remains the one promising control strategy for this disease. Our research modeled the potential effects of introducing an iNTS vaccine. The findings are of great importance to Mali and other developing countries where young children are at a high risk of developing iNTS disease.