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Meningococcal DiseaseUpadated: May 2005 Know before you go!Infectious diseases not necessarily common in Canada can occur and may even be widespread in other countries. Standards of hygiene and medical care may differ from those at home. Before departure, you should learn about the health conditions in the country or countries you plan to visit, your own risk of disease and the steps you can take to prevent illness. The risk is yours Risk assessment consultation Some facts from the experts
Meningococcal meningitis, a form of meningococcal disease, is a contagious disease caused by the bacterium, Neisseria meningitidis. Meninigitis is an inflammation of the lining of the brain and spinal cord that without immediate treatment, can lead to rapid death or permanent brain damage, particularly in young children. *For the purpose of this document, the term meningitis will refer specifically to Meningococcal disease. There are 13 recognized serogroups of Neisseria meningitidis. The groups A, B and C account for roughly 90% of outbreaks of meningococcal disease; groups Y and W-135 are less common causes of infection. Vaccines providing coverage against groups A, C, Y and W-135 have been developed, however no vaccine is yet available to offer protection against group B. Meningococcemia, another form of meningococcal disease, results from an overwhelming infection of the blood and can be more serious, with a higher fatality rate than meningitis. Transmission
Sporadic episodes of meningitis occur around the world with seasonal variation. Temperate regions usually experience epidemics in the winter-spring period while tropical regions see increased disease activity during the dry season. The highest burden of the disease occurs in sub-Saharan Africa in an area referred to as the meningitis belt. This area extends from Senegal in the west to Ethiopia in the east (see Table 1). In temperate climates, most cases occur in winter and spring whereas in the semi-arid climate of the meningitis belt, cases occur between December and June. In 2002, outbreaks occurring in Burkino Faso, Chad, Ethiopia and Niger accounted for approximately 65% of the total cases reported in the African continent. For on-going information on Meningoccocal disease outbreaks, please refer to the Public Health Agency of Canada's International Reports of Meningitis.
Source: World Health Organization, 2005-05-05
Serogroups B and C are the most frequent causes of sporadic cases and outbreaks of meningococcal disease in Europe and the Americas. Serogroup A has historically been the main cause of epidemic disease worldwide and still dominates in Africa and Asia. There is increasing evidence of serogroup W135 being associated with outbreaks of considerable size. In 2000 and 2001 several hundred pilgrims attending the Hajj in Mecca, Saudia Arabia were infected with N. meningitidis W135, importing the disease to their home countries upon return. As a result, a certificate of vaccination against meningococcal meningitis is now required of visitors to Mecca for Umra or Hajj. Additionally, in 2002, W135 emerged in Burkina Faso, striking 13,000 people and killing 1,500. In CanadaMeningococcal disease occurs in Canada with periods of increased activity approximately every 10 to 15 years, but with no consistent pattern. Information detailing Canadian outbreaks between the period of January 1999 to December 2001 can be viewed in the February 1st, 2004th edition of the Canadian Communicable Disease Report. Reports indicate that serotypes B and C remain responsible for most of the cases of meningococcal disease in Canada. Of the 805 cases reported for 1999, 2000 and 2001, 585 were caused by either serotype B or C. The majority of cases of serotype B occur in children younger than five years of age while serotype C has a peak incidences rate in children younger than five years of age and in adolescents between the age of 15 to 19.
The incubation period for meningitis is between two to 10 days, most often ranging between three and four days. Symptoms include the sudden onset of intense headache, fever, nausea, vomiting, photophobia (aversion to light) and stiff neck. Neurological signs include lethargy, delirium, coma and/or convulsions. Infants and newborns may not present with the classic symptoms listed above, exhibiting instead extreme irritability or lethargy. Many people infected with meningitis do not develop symptoms however are carriers and therefore can spread the illness to others. Meningococcemia, although less common, is more severe and is characterized by a haemorrhagic rash, rapid circulatory collapse and a high fatality rate.
Meningococcal disease is a medical emergency, requiring early diagnosis, hospitalization, and effective treatment. When the infection is diagnosed and treated early, antibiotics can be effective in arresting the illness and reducing fatalities. Without treatment, 50% of those infected may not survive. Even with prompt medical treatment, five to10% of patients may not survive, while up to 20% of those who do survive a severe case may have persistent neurological defects after recovery.
There are five meningococcal vaccines approved for use in Canada. Purified Capsular Polysaccharide Vaccines (Men-Ps)
Protein-Polysaccharide Conjugate Vaccines (Men-conjugate)- providing protection against serotype C only.
It is important to note that young children, particularly those under 10, vaccinated with either the quadrivalent or bivalent purified capsular polysaccharide vaccines (MenAC-Ps, MenACYW-Ps) acquire limited protection from the serogroup C component of these vaccines. Moreover, the vaccine does not provide long-term protection for any age group. By contrast, studies have shown that monovalent C vaccine is very effective in young children as well as providing sustained protection.
Some international travellers may be at risk of acquiring meningitis abroad due to the nature and location of their travel. As meningitis is air-borne and can be spread person-to-person, t ravel in an area of high meningitis prevalence; prolonged duration of exposure; and activities which intensify exposure, such as health care work involving close, unprotected contact with infected persons, work with refugees, and back-packing may increase the risk of exposure to meningitis. Additionally, t he nature and circumstances of contact with local people is important in determining a traveller's risk of exposure. Those who will be in close contact with the local population through accommodation, public transport or work are considered to be at higher risk.
For more information…Further information on meningitis and on meningococcal vaccines: From the Public Health Agency of Canada's:Travel Medicine Program:
Other Sources
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Last Updated: 2005-05-16 |