So far, many features of Sp1 remain intriguing, including why it causes sepsis, pneumonia and empyema in Europe and North America (lineage A) and meningitis in the African meningitis belt, where it assumes specific features of infection (hyperendemicity, seasonal pattern and high lethality affecting all age groups) (lineage B) [13,14]. This evidence concerns the gene SP1 and susceptibility to pneumonia measurement.