Neisseria meningitidis is the leading cause of bacterial meningitis worldwide. In developed countries, most cases are caused by endemic disease, although there are appreciable cyclical fluctuations in meningococcal disease incidence, resulting in outbreaks and epidemics.
It is well known that international travel and migration has helped the spread of meningococcal disease around the world.
Serogroup A and to a lesser degree serogroup C have dominated in past epidemics, mainly in Africa. Serogroup W135 first emerged in Saudi Arabia and rapidly spread to other areas, particularly West Africa. Meningococcal disease occurs in all countries and risk assessment is an important consideration before travelling.
Infection is acquired by inhaling infected droplets of respiratory secretions from a carrier's nose and throat or by direct contact (especially kissing) with a patient or carrier. Frequent or prolonged contact encourages transmission of the infection.
Risk factors include smoking, living in close proximity - as in colleges, military barracks, halls of residence, Hajj and other pilgrimages - poor living conditions and overcrowding.
In temperate climates most epidemics occur during winter to spring.
Globally, meningococcal disease affects up to 1.2 million people per year, causing 135,000 deaths. The 'meningitis belt of Africa', stretching from Senegal in the west to Ethiopia in the east, is a hyperendemic area and carries the highest burden of meningococcal disease in sub-Saharan Africa. The risk is highest in the Savannah during the dry season, between the end of November and June.
Even with appropriate treatment, meningococcal disease mortality is around 10 per cent with 11-19 per cent of survivors being left with permanent neurological sequaelae.1
Travellers at risk of meningococcal infection are those travelling to endemic areas during the dry season. Most at risk are those who have direct contact with the local population, particularly healthcare workers, those visiting friends and relatives, backpackers, pilgrims and long-term travellers.
The risk is greatest during epidemics. In comparison with the low incidence in the UK (1-3 cases per 100,000), during epidemics in sub-Saharan Africa as many as 1,000 per 100,000 population may be affected.2 Travellers are well advised to avoid, where possible, overcrowded conditions.
Immunisation for travellers
Travellers at risk need broad protection against meningococcal serogroups that are more prevalent abroad, namely A, C, W and Y. Two quadrivalent vaccines are licensed in the UK.
The polysaccharide meningococcal vaccine ACWY is poorly immunogenic in patients under 24 months of age. It is best given to children aged five years and above. Protection lasts for at least three years. There is no induction of immunological memory.
The conjugate meningococcal ACWY vaccine (MenACWY) is immunogenic in young children and can reduce nasopharyngeal carriage. It is not licensed for children under 11 years as yet.
Nonetheless, the Green Book3 recommendation is that, based on the experience with other conjugate vaccines, immunity is expected to be higher, longer-lasting and confer less risk of immunological tolerance than the polysaccharide vaccine. It recommends the MenACWY in preference to polysaccharide vaccine in children under five years of age,3 and the use of MenACWY outside its licence for children travelling to endemic areas and at risk, aged two months and over.
The Hajj pilgrimage to Mecca is the largest annual gathering of its kind in the world. When applying for a visa to Saudi Arabia, it is mandatory for all pilgrims to submit proof of vaccination with the quadrivalent ACWY vaccine. It should have been received no more than three years and not less than 10 days before travel to Saudi Arabia.
In the case of asplenia or splenic dysfunction the advice has recently changed. The Green Book recommendations are as follows:3
Children under one year:
- At two and three months administer MenACWY (two doses one month apart) instead of MenC;
- At 12 months administer Hib/MenC vaccine;
- At 14 months (or two months later) give one dose of MenACWY vaccine
Children over one year and adults:
- One dose of Hib/MenC vaccine followed by single dose of MenACWY two months later.
Children and adults who have been fully immunised with MenC vaccine as part of the routine programme, but who then develop splenic dysfunction:
- Administer an additional dose of the combined Hib/MenC vaccine, followed by a single dose of MenACWY vaccine two months later.
|Global Serogroup Distribution|
Global serogroup distribution of meningococcal disease and serogroup importance4
- Dr Kassianos is the RCGP immunisation lead and fellow and honorary secretary for the British Travel Health Association.
1. Rosenstein NE, Perkins BA, Stephens DS. N Engl J Med 2001; 344(18): 1,378-88.
2. Pollard AJ. Pediatr Infect Dis J 2004; 23(12 Suppl): S274-9.
3. The Green Book. 22 Meningococcal.
4. Stephens DS, Greenwood B, Brandzaeg P. Lancet. 2007; 369: 2,196-210.