Haemophilus influenzae type b (Hib) infection

Haemophilus influenzae type b is a bacterium that lives quietly in the nose and throat of a proportion of perfectly healthy people. Trouble begins when it breaks through the lining into the bloodstream: within hours it can produce meningitis, inflammation of the epiglottis, or blood poisoning. Children in their first few years fare worst. The good news is that a vaccine exists, and wherever children are routinely given it the illness has gone from common to rare.

Why the name misleads

The word influenzae is a leftover from a mistake made in the late nineteenth century: the bacterium was isolated from patients during a flu epidemic and assumed to be the cause. The real culprit, a virus, was identified later, but the bacterium's name was never changed. Hence a muddle worth clearing up at once: this bacterium has nothing to do with flu, and the Hib vaccine gives no protection against flu. They are different illnesses and different vaccines.

A second point: the bacterium comes in several varieties. Type b is the most aggressive of them, it was the one causing severe childhood infections, and it is the one the vaccine was built against. The others tend to cause ear infections, sinusitis and bronchitis, and the vaccine does not cover them.

What it turns into

While the bacterium sits in the nose and throat the person is well and generally has no idea they are carrying it. The infection becomes dangerous once the organism crosses into the blood and spreads through the body. That single source produces several distinct illnesses:

• Meningitis — inflammation of the membranes around the brain and spinal cord. Before the vaccine this was the commonest form.
• Epiglottitis — inflammation of the epiglottis, the cartilage flap above the entrance to the voice box. Once swollen it closes off the airway, and it does so very fast.
• Sepsis — the body's response to infection in the blood turning on its own organs: blood pressure drops, circulation falters, the kidneys fail.
• Pneumonia, sometimes with fluid collecting around the lung.
• Septic arthritis and osteomyelitis — infection of a joint or a bone.
• Cellulitis — deep infection of the skin and the tissue beneath it, in small children most often on the face and around the eye.

Even when treatment starts promptly, some children are left with lasting damage: hearing loss up to deafness, seizures, hydrocephalus, learning difficulties; after severe sepsis, fingers or limbs are sometimes lost. That is the strongest argument for vaccinating: the infection can be treated, but what it takes cannot be given back.

Signs that mean calling an ambulance

Hib infection unfolds over hours, and there is nothing here worth waiting for. Call an ambulance at once — in Spain, Italy, Portugal, Poland and Ukraine that is the single European number 112 — if any of the following appears.

Breathing:

• the child is struggling to breathe, sitting bolt upright and leaning forward with the chin pushed out, because in any other position there is not enough air;
• noisy, whistling or rasping breathing in;
• drooling, because swallowing hurts or has become impossible;
• a muffled voice, as though the mouth were full, and speech is an effort;
• a sore throat so severe that the child refuses even to drink;
• lips, tongue or skin turning blue, grey, or blotchy.

An important warning: with these signs, do not try to look into the throat with a spoon and do not lay the child on their back. Either can close the airway completely. Let the child sit however they find comfortable and stay with them.

Nervous system and circulation:

• a seizure;
• the child cannot be woken, is unusually floppy, or will not settle and cries in a high-pitched way;
• a tense, bulging fontanelle in a baby;
• severe headache with a stiff neck and dislike of light;
• a rash of small bleeds resembling bruises or pinpricks that does not fade when pressed with the side of a glass;
• cold, mottled skin with icy hands and feet despite a high temperature;
• very rapid breathing, a listless child who is not responding as usual.

The rash does not always appear, and often appears late — it is not something to wait for. If a child is going downhill quickly and you have the sense that something serious is happening, trust it: parents register the change before any scoring chart does. Do not drive yourself, call for help, and bring along whatever medicines the child takes.

When a doctor is needed the same day

Most childhood fevers are caused by viruses. But some signs mean the child is seen today rather than in a few days:

• a high temperature in a baby in the first months of life;
• fever lasting beyond three days, or returning after an apparent improvement;
• refusing to drink, passing noticeably less urine than usual, nappies staying dry;
• relentless vomiting with nothing staying down, food or fluid;
• a new limp, refusing to let an arm or leg be touched, a joint that is swollen and hot;
• an area of skin, particularly on the face or beside the eye, that is red, swollen and painful;
• a child without a spleen or with weakened immunity who develops a fever — for them assessment is not postponed.

How it is treated

Invasive Hib infection is treated in hospital. The mainstay is intravenous antibiotics, started as soon as the suspicion is well founded and without waiting for cultures, because delay here is more dangerous than a course given unnecessarily. Once the organism is identified, the regimen is refined.

The rest depends on the form. In epiglottitis the first job is keeping the airway open, and the child is usually intubated in theatre where everything is ready. In meningitis a short course of steroids is sometimes added to the antibiotics, which lowers the risk of hearing loss. Sepsis calls for oxygen, intravenous fluids and drugs to support blood pressure. Pus in a joint or around a lung sometimes has to be drained surgically.

The household is a separate matter. If there are unvaccinated children or people with weakened immunity living there, doctors may prescribe everyone in the home a short preventive course of an antibiotic and check the vaccination records at the same time. That is a medical decision; such courses are not something to arrange on your own.

The vaccine that changed the picture

Before routine vaccination, Hib was among the leading causes of bacterial meningitis in children under five. After it was introduced, cases fell by a factor of tens, and doctors in many countries now see this infection only a handful of times in a career.

It is a conjugate vaccine: a fragment of the bacterial coat is linked to a carrier protein, which is what allows even babies to mount a proper response. It is almost never given as a separate injection — the Hib component sits inside the combined childhood vaccines alongside protection against whooping cough, diphtheria, tetanus and other infections, so it adds no extra jabs.

On timing. The principle is the same everywhere: several doses during the first year of life, beginning in the early months, followed by a booster that consolidates protection. The exact months, the number of doses and the make-up of the combined preparation differ from country to country, so go by your own country's national immunisation schedule and by your doctor's advice, not by a schedule read on a foreign website.

Also worth knowing:

• if doses have been missed or the schedule has slipped, a catch-up route exists — starting again from scratch is usually unnecessary, and a doctor will fill in what is outstanding;
• older children and adults are not vaccinated as a matter of routine, because susceptibility falls with age;
• certain groups are vaccinated whatever their age, above all people without a spleen or with a spleen that does not work, and some with disorders of immunity;
• the vaccine covers type b only and does not protect against meningococcus, pneumococcus or viral meningitis, each of which has its own vaccines;
• having had the illness does not always leave lasting protection, so young children who recover are generally vaccinated anyway.

How it spreads and who is most at risk

The route is the same as a cold: droplets from coughing and sneezing, and shared cups, dummies and toys that go into a child's mouth. A perfectly healthy carrier who has no idea they are carrying it can pass it on, so tracing the source is generally impossible and isolating the ill does not settle the problem.

The worst affected are:

• children from roughly six months to five years, especially in the second year: antibodies from the mother have faded by then and the child's own have not yet formed;
• those unvaccinated or only partly vaccinated;
• people without a spleen or with one that functions poorly, including in sickle cell disease;
• people with weakened immunity — after chemotherapy, with certain inherited disorders, with HIV;
• older people and those with long-term lung disease;
• children living in crowded conditions or in large groups.

Ordinary hygiene helps without solving everything: washing hands, not sharing cups, coughing into the elbow, and no smoking indoors, since respiratory infections run harder in children growing up in tobacco smoke.

Online consultation

An online consultation suits the calm questions well: which vaccines a child has already had, what is missing, how to build a catch-up schedule after an illness or a move, whether an adult without a spleen or after chemotherapy should be vaccinated. The doctor will go through your records, explain what the names of the combined vaccines mean, and set out which signs to watch for in an unwell child and which of them cannot wait. If the question is laboured breathing, a seizure or a rash that will not fade under a glass, an online appointment is not the answer — call an ambulance.

This material is for information only and does not replace medical advice.