Difference in language use across Africa may introduce a bias in our study if we limit the source of information to one specific language. We therefore included studies written in French as well as those written in English because French is the predominant language in many West and Central African countries. Use of diagnostic methods with low specificity is another factor that may introduce a bias in our study. Typhoid fever confirmed by clinical diagnosis or Widal tests will likely include false-positive cases. This may lead to an overestimation, and its extent may vary by time and location. To avoid this potential bias, we included typhoid fever confirmed by culturing blood, stool, urine, or bone marrow samples in the primary analysis and included the rest in the secondary analysis for comparison. On the other hand, isolation of Salmonella Typhi from blood, a definitive diagnosis of typhoid fever, is known to have <60% sensitivity [7], leading to underestimation.