This picture shows the organism Haemophilus influenza. Infections caused by Haemophilus influenza usually occur in children under 6 years old and are extremely serious. Haemophilus (type B) is responsible for meningitis, periorbital cellulitis, buccal cellulitis and epiglottitis, septic arthritis, osteomyelitis, pericarditis, and bacteremia. The small organisms live within cells (intracellular) as shown in this picture. (Image courtesy of the Centers for Disease Control and Prevention.)

Periorbital cellulitis is an acute infection of the tissues surrounding the eye, which may progress to orbital cellulitis with protrusion of the eyeball. Complications include meningitis.

This is a gram stain of spinal fluid from a person with meningitis. The rod-like organisms seen in the fluid are Haemophilus influenza, one of the most common causes of childhood meningitis (prior to the widespread use of the H. influenza vaccine). The large red-colored objects are cells in the spinal fluid. A vaccine to prevent infection by Haemophilus influenza (type B) is available as one of the routine childhood immunizations (Hib), typically given at 2, 4 and 12 months.