Haemophilus influenzae type b (Hib) infection

Haemophilus influenzae is a family of bacteria, and type b is the strain with a protective capsule that lets it invade the bloodstream and the lining of the brain. The NHS describes Hib as a bacterium that can cause life-threatening infections, with babies and young children at greatest risk. It spreads the way colds and flu do, through respiratory droplets released by sneezing and coughing, and many people can carry it in the nose and throat without becoming ill.

The name is misleading: Haemophilus influenzae does not cause influenza. It was wrongly thought to be the cause of flu in the 1890s, and the name stuck.

Hib can lead to several serious diseases, as the NHS lists. Meningitis, infection of the membranes around the brain, can follow rapidly. Sepsis occurs when the infection overwhelms the body. Epiglottitis is swelling of the flap above the windpipe and can block breathing within hours, and pneumonia affects the lungs. Joint and bone infection, cellulitis around the face and infection of the lining of the heart are less common presentations.

The NHS notes that even after successful treatment, survivors can have lasting problems including hearing loss, seizures, loss of limbs and cognitive impairment, which is why prevention matters so much.

• Meningitis: fever, headache, neck stiffness, drowsiness, photophobia, bulging fontanelle in babies.

• Epiglottitis: sore throat, muffled voice, drooling, noisy breathing, and a child sitting forward to breathe.

• Sepsis: fast breathing, mottled or pale skin, extreme sleepiness, non-blanching rash.

• Pneumonia: cough, fast breathing and fever.

The NHS lists high fever, breathing difficulties, unusual sleepiness, discoloured skin or lips, a non-blanching rash that looks like bruising, headache, sore throat and joint swelling. Babies may be floppy, refuse feeds or cry in an unusual high-pitched way. Because Hib disease is now rare, doctors still treat these presentations as emergencies first and consider which bacteria are responsible once antibiotics are under way.

Never delay seeking help while waiting for a rash. In a child with breathing difficulty, noisy breathing or drooling, call 999 and keep the child calm and upright, avoiding any attempt to look into the throat.

Diagnosis relies on clinical assessment, blood cultures and, when meningitis is suspected and it is safe, a lumbar puncture. Epiglottitis is managed by senior anaesthetic and ENT staff to secure the airway. The NHS states that the main treatment for Hib infection is antibiotics, usually given in hospital, with oxygen and steroids used depending on the symptoms.

Close contacts of a case, particularly unvaccinated young children, may be offered preventive antibiotics and vaccination on advice from the local health protection team.

The NHS states that vaccination is the best way to prevent serious Hib infections. Hib protection is part of the 6-in-1 vaccine, which also covers diphtheria, hepatitis B, polio, tetanus and whooping cough. The NHS schedule is four doses at 8 weeks, 12 weeks, 16 weeks and 18 months of age. The vaccine is not suitable for a child who has had anaphylaxis to a previous dose or to one of its ingredients, and vaccination is delayed during a high fever.

Common side effects include swelling or tenderness at the injection site, fever, tiredness, reduced appetite and fussiness, which children's paracetamol can ease. The NHS notes missed doses can still be given up to age 10, so contact the GP surgery if any were missed. Hib vaccination protects against type b only and does not prevent other types of Haemophilus influenzae, which cause milder illness such as ear and chest infections.

The NHS lists people with weakened immunity, including those without a spleen, and elderly people as being more vulnerable. People who have had their spleen removed or have sickle cell disease are usually offered additional vaccines and advised about antibiotic cover. If you are unsure whether you are up to date, ask your GP practice.