Cases of invasive meningococcal disease reported in travellers returning from the Kingdom of Saudi Arabia

As of 17 May 2024, twelve cases have been reported, from France (4), the United Kingdom (UK) (3), and the United States (US) (5). Almost all cases reported performing Umrah pilgrimage while in the KSA. The majority of cases belong to meningococcus serogroup W and have no history of meningococcus vaccination.

Whole genome sequences deposited at pubmlst.org fall into a multi-country cluster, with sequences from 2024 reported by France (3), the United Kingdom (4),* and the United States (1), along with historical isolates reported by Germany (one sequence, 2015) and the Russian Federation (two sequences, 2019 and 2020). Of these, one sequence from France, four from the UK and one from the US, all from samples collected in 2024, form a very tight subcluster, which indicates an epidemiological link.

IMD is an acute severe bacterial infection, with high case fatality, presenting with meningitis and/or sepsis, often with a rapid progression, requiring medical support and prompt treatment with antibiotics. The highest incidence occurs in young children, adolescents and young adults.

According to routine surveillance data submitted to ECDC, 1 149 IMD cases were reported in EU/EEA countries in 2022. Among cases with serotype information available, serogroup B was the most frequent (62%), whereas serogroup W accounted for 10% of cases. Overall, between 2018 and 2022, 1 096 cases of serogroup W infections were recorded. Meningococcus serogroup W has been associated with higher disease severity and case fatality. 

ECDC assesses the risk of IMD to the general public in the EU as very low due to the very small probability of exposure and potential infection. For pilgrims visiting the Hajj and Umrah zones in KSA who are vaccinated with the quadrivalent meningococcal vaccine, the likelihood of infection is low, as they are protected thanks to vaccine-induced immunity. For unvaccinated pilgrims visiting these sites, the likelihood of infection is moderate. 

In relation to this incident, ECDC recommends the following measures to EU/EEA public health authorities: 

• Ensure that travellers to the Hajj and Umrah zones in KSA eligible for vaccination are counselled to receive the quadrivalent (ACWY) meningococcal vaccine at least 10 days before departure.
• Raise awareness among clinicians for early suspicion of meningitis in returning travellers and include travel history in their assessment of IMD cases, particularly where there has been travel to KSA for religious purposes.
• Appropriately manage newly-detected cases. Early suspicion and treatment, isolation of meningitis cases, identification of close contacts, provision of chemoprophylaxis, and monitoring of close contacts for clinical symptoms for at least 10 days from the last possible exposure are essential for the management of cases. Healthcare workers managing suspected or confirmed cases should follow their national infection, prevention and control protocols.
• Continue surveillance, including molecular surveillance, as well as antibiotic susceptibility testing of all IMD cases, to inform prevention and control measures. IMD cases, particularly if linked to travel to the Hajj and Umrah zones, should be promptly reported to the EpiPulse platform [through nominated persons] to allow better risk assessment and the provision of updated recommendations.
• Meningococcal isolates should be genotyped by whole genome sequencing and reported to pubmlst.org or to the European Meningococcal Epidemiology in Real Time database (EMERT-II) to allow for the rapid identification and control of multinational clusters. ECDC can provide sequencing support upon request.

* The number of sequenced samples does not directly correspond to the number of reported cases; multiple samples can be sequenced from the same patient.