Every year Saudi Arabia hosts international pilgrims from approximately 160 countries, for both the Hajj and Umrah seasons. Annual outbreaks of Neisseria meningitidis disease occur during the Hajj season, when 1.5–2 million pilgrims converge on Mecca and Medina in Saudi Arabia. The majority of the pilgrims are international travelers. Crowded conditions and close contact with people from various parts of the world are both known risk factors for the transmission of meningococcus. Pilgrims to the Hajj have been considered to be at an increased risk of carrying and developing invasive illness for many years [1, 2].
In 1987, N. meningitidis serogroup A caused a large outbreak of meningitis amongst pilgrims in Mecca and other countries. This led to the introduction of bivalent meningococcal vaccination (A, C) as a requirement for entry into Saudi Arabia during Hajj and Umrah [2].
Neisseria meningitidis serogroup W135 was responsible for two international outbreaks in association with the Hajj pilgrimages in Saudi Arabia in the years 2000 and 2001 [1]. During the 2000 Hajj, more than 400 cases of meningococcal meningitis due to serogroup W135 were reported in pilgrims and their close contacts from 16 countries (United Kingdom, Belgium, USA, France, Morocco, Kuwait, Oman, Indonesia, Singapore, Denmark, Finland, Sweden, Norway, Germany and Netherlands) [2]. This was followed by a smaller outbreak during the pilgrimage of 2001, when close to 200 cases, all linked to the Hajj pilgrimage, were identified world-wide, including Saudi Arabia. Fifty-five of the cases were reported to have died from meningococcal infection contracted during the Hajj [1].
These outbreaks generated particular interest, as serogroup W135 was not then known to cause major outbreaks. Molecular typing of W135 isolates from this outbreak showed the W135 to be of clonal origin (ET 37) and closely related to other meningococci, with an established propensity to cause disease clusters. The origin of W135 remains unclear. Meningococci belonging to serogroup W135 have been isolated from African patients with meningococcal disease since the early 1980s. It is conceivable that Moslems from African countries may have introduced the pathogenic strain into Saudi Arabia during the Hajj. It is believed that the W135 ET-37 clone is related to strains isolated in Mali and the Gambia in the 1990s. Generally, it seems that N. meningitidis W135 has been circulating and causing meningococcal disease for more than 20 years [1–3].
As a result, the 4-valent (A, C, Y and W135) meningococcal vaccine has become a mandatory visa requirement for all pilgrims since 2002 [2]. In general, meningococcal vaccine is recommended for travelers to the African meningitis belt, in particular during the dry season (December to June) and for those traveling to areas with an active outbreak (CDC and WHO recommendations).
References
- Balkhy HH, et al. Meningococcal carriage among local inhabitants during the pilgrimage 2000-2001. Intl J Antimicrob Agents 2003;21:107-111.
- Wilder-Smith A, Memish Z. Meningococcal disease and travel. Int J Antimicrob Agents 2003;21:102-106.
- Wilder-Smith A, et al. Acquisition of W135 meningococcal carriage in Hajj pilgrims and transmission to household contacts: prospective study. Br Med J 2002;325:365-366.
Paraskevi Smeti, Androula Pavli, Maltezou Elena Travel Medicine Office, Department for Interventions in Health Care Facilities
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