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MenW disease around the world



Worldwide distribution of major meningococcal serogroups

The incidence of meningococcal disease can vary substantially by geographic location and time. The disease can occur as sporadic cases, outbreaks, and large epidemics.

Historically meningococcal group W (MenW) has caused only a small proportion of meningococcal infections globally1. MenW tends to be more prevalent outside of Europe with outbreaks being recorded in Africa and South America. Large epidemics of MenW disease were associated with the Hajj pilgrimage in 2000-2002 and the UK and other countries saw a corresponding spike in UK cases when pilgrims returned home and disease spread amongst close contacts2.

For this reason the ACWY vaccine is recommended for those travelling to high risk areas and is a compulsory entry requirement into Saudi Arabia for pilgrims on Hajj and Umrah, and for other travellers in Hajj season.

More about the ACWY as a travel vaccine

More about MenW

ST-11 disease around the world


ST-11 strains have historically caused significant outbreaks of meningococcal disease across the globe:

  • In the 1990s a ST-11 meningococcal bacteria caused a large group C outbreak in Canada before spreading globally1
  • The increase of group C disease in the United Kingdom in the 1990s was also caused by ST-11 which caused outbreaks in universities and a high number of deaths3
  • In 2000 ST-11 was responsible for an outbreak of W in Mecca, Saudi Arabia, with subsequent global spread of the epidemic strain4
  • From 2002 to 2004 ST-11 caused epidemics of group W disease across Africa5
  • Since 2005 ST-11 has been identified as responsible for increased group W disease in South Africa and South American countries such as Brazil, Argentina and Chile4
  • Since 2009 there has been a rise in cases of ST-11 group W disease in England and Wales6

References

  1. Harrison, L.H., C.L. Trotter, and M.E. Ramsay, Global epidemiology of meningococcal disease. Vaccine, 2009. 27 Suppl 2: p. B51-63.
  2. Hahne, S.J., et al., W135 meningococcal disease in England and Wales associated with Hajj 2000 and 2001. Lancet, 2002. 359(9306): p. 582-3.
  3. Gray, S.J., et al., Epidemiology of meningococcal disease in England and Wales 1993/94 to 2003/04: contribution and experiences of the Meningococcal Reference Unit. J Med Microbiol, 2006. 55(Pt 7): p. 887-96.
  4. Lingappa, J.R., et al., Serogroup W-135 meningococcal disease during the Hajj, 2000. Emerg Infect Dis, 2003. 9(6): p. 665-71.
  5. Traore, Y., et al., The rise and fall of epidemic Neisseria meningitidis serogroup W135 meningitis in Burkina Faso, 2002-2005. Clin Infect Dis, 2006. 43(7): p. 817-22.
  6. Shamez N. Ladhani, et al. Increase in endemic Neisseria meningitidis capsular group W ST-11 complex associated with severe invasive disease in England and Wales. Clinical Infectious Diseases 2014 [cited Advance access November 10]; Available from: http://cid.oxfordjournals.org/content/early/2014/11/10/cid.ciu881.abstract.


What is MenW ST-11?

Meningococcal bacteria are classified according to structural differences in certain components. The serogroup, e.g. A, B, C, W or Y, is defined by the type of sugar coat, or capsule, that surrounds the bacteria.

Meningococcal bacteria can also be classified according to certain parts of their genetic make-up. This type of classification is known as Multi Locus Sequence Typing (MLST) and it is based on similarities between seven ‘housekeeping’ genes within the meningococcal genome. The advantages of classifying bacteria in this way is that it can provide information about how bacteria are evolving over time and the information can easily be shared between laboratories and researchers1. This is one of the reasons why our genome library is such a useful resource.

Genetic sequences which are identical across the seven housekeeping genes will belong to a given sequence type (ST). Meningococcal bacteria belonging to ST-11 have been identified as especially virulent and have been associated with outbreaks that particularly affect healthy people in their prime, namely teenagers and young adults.

  1. Maiden, M.C., et al., Multilocus sequence typing: A portable approach to the identification of clones within populations of pathogenic microorganisms. Proc Natl Acad Sci U S A, 1998. 95(6): p. 3140-5.