Haemophilus-Influenzae Type B (Hib)

Haemophilus Influenzae Type B is a bacteria which used to be responsible for the majority of cases of pneumonia and meningitis, until the Hib vaccine was made available.  Almost all its victims are children under the age of 5, but those between the ages of 4 and 18 months are the most vulnerable.

It has been reported that 3 - 6 % of cases are fatal, with about 20% of surviving patients left with permanent disabilities such as mental retardation and deafness. Contrary to what its name might suggests, the Haemophilus Influenzae does not cause influenza.

Infectious Period:

Hib is potentially infectious for as long as the bacteria remains within the nose and throat. However, one is no longer infectious after at least 24 hours of appropriate antibiotic therapy.

Transmission:

Transmission of Hib is via respiratory droplets or direct contact with respiratory secretions. A mother may also spread Hib to her newborn infant during delivery (through aspiration of amniotic fluid or genital tract secretions).

Clinical Features:

Unlike some other diseases like measles or polio, Hib does not cause specific symptoms or signs which would enable it to be readily identified. The most serious forms of Hib infection can result in pneumonia and meningitis, but these conditions may be cause by other infections as well. To confirm the diagnosis Hib infection, samples must be taken — a blood specimen (in the case of pneumonia), and a spinal-fluid specimen by lumbar puncture (in the case of meningitis), and the bacteria must then be isolated from those specimens in a laboratory.

The following may be caused by Hib:
1. Meningitis - symptoms include fever, irritability, lethargy, vomiting and neck stiffness.

2. Pneumonia - symptoms are that of fever, cough, shortness of breath and sometimes chest pain.

3. Epiglottitis - symptoms include a high fever, sore throat, stridor (a high pitched wheezing sound caused by an obstruction in the upper airway) and shortness of breath. This rapidly progresses to dysphagia (difficulty swallowing), pooling of secretions in the mouth, and drooling. The child is usually restless and adopts a sitting position with the neck extended and chin protruding, in the attempt to reduce obstruction of the upper airway. Unless there is early medical intervention to secure the upper airway, rapid deterioration and death can occur.

4. Septic arthritis (bacterial infection of the joints)

5. Septicaemia (blood poisoning)

Treatment:

Depending on the disease caused by Hib and its severity, hospitalization may be required. As Hib is a bacteria, treatment is with the appropriate antibiotics. A child with epiglottitis or severe pneumonia/septicaemia, may need to be cared for in an intensive care unit.

Prevention and Control:
Patients with invasive Hib disease will need to be isolated for at least 24 hours after starting antibiotics.

Prophylactic antibiotics for household contacts may need to be considered.

Immunisation is the best protection against Hib infection and is recommended for all infants, young children and adults at high risk.

In Singapore, the recommended series of Hib conjugate vaccines consists of 3 primary doses given within the first 6 months of life with a booster dose given at 12 - 18 months of age. It is usually given in combination with diphtheria, tetanus, acellular pertussis (DTap), and inactivated polio (IPV) in the 5-in-1 vaccine, or with Hepatitis B in the 6-in1-vaccine.

A single dose of Hib vaccine is also recommended for anyone who has no spleen or a poorly functioning spleen and has not been previously immunised for Hib. People who have had a stem cell transplant should also be given Hib vaccine.

The article above is meant to provide general information and does not replace a doctor's consultation.
Please see your doctor for professional advice.