The bacillus haemophilus influenza causes

Haemophilus influenzae (formerly known as Pfeiffer's bacillus) is a Gram-negative bacterium. Despite its name, it does not cause influenza, which is caused by the influenza virus. Haemophilus influenzae type b (Hib) is a major cause of serious invasive infections, most notably bacterial meningitis in infants and young children. Before the widespread use of the Hib vaccine, it was the leading cause of non-epidemic bacterial meningitis in children under five years of age. While the bacterium can also cause pneumonia, epiglottitis, and sepsis, it is most classically associated with pediatric meningitis in medical literature. Whooping cough is caused by the bacterium Bordetella pertussis.