Meningococcal infection is caused by the bacteria Neisseria meningitidis.
The clinical picture may be variable. It may result in severe illness when the bacteria invade the bloodstream (meningococcaemia) or the membranes that envelop the brain and spinal cord (meningococcal meningitis). Meningococcaemia is characterised by sudden onset of fever, intense headache, purpura, shock and even death in severe cases. Meningococcal meningitis is characterised by high fever, severe headache, stiff neck followed by drowsiness, vomiting, fear of bright light, or rash; it can cause brain damage or even death. The brain damage may lead to intellectual impairment, mental retardation, hearing loss and electrolyte imbalance. For invasive meningococcal infection, it can be complicated by inflammation of joints, inflammation of heart muscle, inflammation of the posterior chamber of the eye or chest infection.
Mode of transmission
The disease is mainly transmitted by droplets via sneezing or coughing or by direct contact through respiratory secretions from infected persons.
The incubation period varies from 2 – 10 days, commonly 3 – 4 days.
Meningococcal infection is a serious illness. Patients should be treated promptly with antibiotics. Close contacts would need to be placed under medical surveillance for early signs of disease and may be given preventive medications.
Risk of infection
The risk of infection is higher among close contacts of patients with meningococcal infections. Close contacts include (1) family members, (2) day care centre contacts, (3) persons directly exposed to the patient's oral secretions, and (4) those who frequently sleep or eat in the same dwellings as the patient. Certain patients with defective immune systems are also at higher risk. Other risk factors include antecedent viral infection, overcrowding, chronic illness, and active and passive smoking.
In general, the risk of acquiring meningococcal infection while travelling is low. However, in sub-Saharan Africa extending from Senegal to Ethiopia, particularly during the dry season (December to June), disease occurrence is higher, and there is additional risk for long-term travellers living in close contact with the indigenous population.
1. Maintain good personal hygiene
2. Maintain good environmental hygiene
3. Advice to travellers
Meningococcal vaccines have been registered in Hong Kong. To minimise the risk of meningococcal infection, vaccination may be considered for the following groups of travellers:
Travellers should seek professional advice from doctors for vaccination in view of the individual’s age and health condition, and details of the journey such as place, duration and nature.