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| International Distribution of serogroups of Neisseria meningitidis prevalent Source: Committee to Advise on Tropical Medicine and Travel (CATMAT). Statement on Meningococcal Vaccination for Travellers. Canada Communicable Disease Report 2009 Volume 35 - ACS-4 http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/09pdf/acs -dcc-04.pdf 13 serogroups of Neisseria meningitidis, identified on the basis of capsular polysaccharide . Of these, five serogroups (A, B, C, W135 and Y) cause most cases of meningococcal disease globally. invasive disease by N. meningitidis (meningitis and sepsis) can occur sporadically or in the form of outbreaks. The map inserted at the beginning of this post shows the international distribution of serogroups. An increased risk of invasive disease by N. meningitidis was observed among individuals who are on their called meningitis belt (sub-Saharan Africa), where outbreaks are frequent during the dry season (which extends from December to June) due to both of environmental factors that may affect the integrity of the upper respiratory tract ( very dry climate, cold nights), both factors social (overcrowding in housing and population movements linked to socio-cultural or religious reasons) (1). These factors may encourage the movement of N. meningitidis. Outside the meningitis belt, the pilgrimage to Mecca (Hajj) is associated with a increased risk of meningococcal disease: why the government of Saudi Arabia requires pilgrims a certificate of vaccination meningococcal (2). outbreaks are regularly reported in other parts of the world, including the Indian subcontinent and other areas of Asia (3). For developed countries, it is interesting evolution of the serogroups in the United States: serogroup Y was responsible for only 2% of all cases in 1989-1991 but later in the mid- 90s, this proportion began to increase. In 2009 (information) serogroup Y became predominant (37%), while the remaining serogroups were as follows: B (32%), C (28%), W135 and other minor (4%) (4). Until now, travelers who went in at-risk areas could be immunized with a unconjugated polysaccharide vaccine containing serogroups AC-W135-Y. As with all unconjugated polysaccharide vaccines, the immunogenicity is not optimal, there is also induction of immune memory, is not prevented the carrier state, there is induction of herd immunity and can be determined hyporesponsive following repeated administration over time. has recently been registered in Europe and the United States, and is also available in Italy, a new conjugate vaccine protein C. diphtheriae CRM197, containing serogroups AC-W135-Y (5.6). Clinical trials conducted on this new vaccine have evaluated the immune response in adults and adolescents for each serogroup by measuring the production of antibodies specific anticapsulari, with bactericidal activity (serum bactericidal activity, SBA). In both adults and adolescents has detected a significantly higher immune response compared to that determined by comparison of non-conjugated polysaccharide vaccine. The vaccine is administered as a single dose, starting from 11 years of age. Has not been established need of reminders. The safety of the vaccine was evaluated in five RCTs with 6185 participants aged between 11 and 65. Among the most common side effects were noted local reactions (erythema, induration, itching, pain at the injection site), and general information such as nausea and headache, lasting 1-2 days. What advantages and what problems has this new vaccine? Benefits are those related to conjugation with a carrier protein: induction of immunological memory , continued protection, booster effect after a new contact with the antigen (because, for the presence of the carrier protein, it is T-dependent antigen), decreased carrier state, induction of herd immunity and no appearance of hyporesponsive after doses after the first. The incident is typical of the hyporesponsive conjugate vaccines: There is evidence that subjects who received one dose of meningococcal vaccine unmarried show a lower immune response to subsequent doses of the same vaccine in some studies this effect is manifested even when, in subjects previously immunized with the unconjugated vaccine, revaccination was carried with a meningococcal conjugate vaccine (7). Problems a) the vaccine is registered for use since the 11 years of age. The passenger under the age of 11 years at the time should be vaccinated with the corresponding product unmarried. It 's interesting, however, that the Green Book UK permits the use of off-label even conjugate vaccine in children under one year. This position Health UK is set out in an updated chapter on meningococcal added in July 2010 (8); b) currently is an expensive product (retail price 88 Euro), but this disadvantage is offset by the fact that is administered in a single dose, while the vaccine unmarried should be repeated after 3-5 years. For pilgrims to Mecca, unfortunately now the Saudi government does not distinguish between old and new vaccine, so continues to restrict the validity of 3 years of vaccination (9) and this represents, together with the high cost , a limitation to its use in this category of travelers. should mention that, due to its characteristics, it is not a vaccine for exclusively for travelers: it can be used in vaccination programs universal in Western countries even if it occurs, or is deemed possible , an increase in cases of illness from serogroups A, Y, W135, as happened in the United States. It can also be used subjects at increased risk for meningococcal disease, such as the asplenia or patients suffering from deficiency of complement factors. Bibliografia (1) WHO. Meningococcal meningitis. Wkly Epidemiol Rec 2003;78:285–96 Available at: http://www.who.int/wer/2003/en/wer7833.pdf (2) Lingappa JR, Al-Rabeah AM, Hajjeh R, Mustafa T, Fatani A, Al- Bassam T, et al. Serogroup W-135 meningococcal disease during the Hajj, 2000. Emerg Infect Dis 2003;9:665–71. (3) Harrison LH, Trotter CL, Ramsay ME. Global epidemiology of meningococcal disease. Vaccine 2009;27(S2):B51-B63 doi: 10.1016/j.vaccine.2009.04.063 (4) Active Bacterial Core Surveillance (ABCs) Emerging Infections Program Network. ABCs Report: Neisseria meningitidis, provisional-2009 [Access 23.10.2010] (5) European Medicines Agency. Menveo. Summary of product characteristics (6) Licensure of a Meningococcal Conjugate Vaccine (Menveo) and Guidance for Use --- Advisory Committee on Immunization Practices (ACIP), Morbidity and Mortality Weekly Report (MMWR) March 12, 2010 / 59(09);273 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5909a5.htm (7) Bröker M and Veitch K. Quadrivalent meningococcal vaccines: Hyporesponsiveness as an important consideration when choosing between the use of conjugate vaccine or polysaccharide vaccine. Travel Medicine and Infectious Diseases 2009;8:47-50 doi:10.1016/j.tmaid.2009.12.001 (8) Immunisation against infectious disease - The Green Book. Updates to Chapter 22: Meningococcal, 28 July 2010 http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/documents/digitalasset/dh_117986.pdf (9) Kingdom of Saudi Arabia. Ministry of Hajj. Saudi Ministry of Health Requirements. http://www.hajinformation.com/main/p3001.htm [Access 23.10.2010] |
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