Meningitis

Part A     Illness, Risk Factors and Prevention

 

I           Etiology                                                                                    

 

Meningococcal meningitis, a form of meningococcal disease is a contagious disease caused by the bacterium Neisseria meningitis.  There are 13 recognized sero groups of N. Meningitis.  The groups A, B and C account for roughly 90% of outbreaks.  Groups Y and W135 are less common causes of infection. (2)

 

Even under optimal conditions, the case fatality rate is 5 to 10%, and may exceed 50% in untreated cases.  (1)  Meningococcal disease is a medical emergency, requiring early diagnosis, hospitalization and effective anti-microbial treatment.

                                                                       

Transmission of Meningitis occurs by direct contact with respiratory droplets from the nose and throat of infected persons.  Fifty percent of cases occur in infants, children and adolescents under 19 years of age, with the highest risk in children under 5 years of age.

 

II  Epidemiology

 

Sporadic episodes of Meningitis occur around the world with seasonal increases in winter and spring. A different cycle of disease is seen in the semi-arid area of sub-Saharan Africa where the largest and most frequently recurring outbreaks occur.  Designated as the “Meningitis Belt”, this area extends from Guinea, Senegal and Southern Mauritania, in the west, to Ethiopia, Northern Kenya and Western Eritrea in the East. (3)

 

III  Indication.

 

Vaccine should be considered for individuals travelling to a region of increased meningococcal disease caused by one of the sero-groups represented in the vaccine. The decision to recommend vaccination should be based on a careful assessment of risk, taking into account the following four factors; destination, nature and duration of exposure, age of traveller, and health of traveller.          

 

1.DESTINATION      

 

Where geographic risk exists, travellers to remote areas without access to reliable care are at highest risk These areas are as follows.

 

TABLE 1                   

 

Countries in the Meningitis belt of Sub-Saharan Africa. Risk is greatest in the dry season(Dec-Jun).

Countries in the traditional African meningitis belt

 

Benin	Ethiopia	Niger
Burkina Faso	Gambia	Nigeria
Cameroon	Guinea	Senegal
Chad	Guinea Bissau	Soudan
Côte d'Ivoire	Ghana
Eritrea	Mali

                    

           

TABLE 2

                       

Areas in Sub-Saharan Africa outside of the traditional meningitis belt in which recent epidemics have occurred within the last 2 to 3 years.

African countries outside the usual boundaries of the African Meningitis Belt in which epidemics were reported in the late 1980s through the 1990s. These areas should be verified for epidemic activity at the above mentioned sources.

 

Angola	Malawi	Uganda
Burundi	Mozambique	Zambia
Central African Republic	Rwanda	Zimbabwe
Democratic Republic of the Congo	Tanzania
Kenya	Togo

 

                                        

                                              

 

2.NATURE AND DURATION OF EXPOSURE

 

Higher risk exists for long-term travellers and those who will be in close contact with the local population through accomodation, public transport and work.

 

Travellers cannot always anticipate the exact nature of exposure in advance of travel. When uncertainty exists, the health care provider should weigh the severity of disease against the potential risk of exposure. Since severe reactions to the vaccine is uncommon and the disease is one that can have a fatal outcome within a very short period, it may be prudent to proceed with vaccination when the traveller is uncertain about the exact nature of exposure.

 

3.AGE OF THE TRAVELLER

 

AGE IS A MAJOR DETERMINANT OF HOST IMMUNITY TO MENNINGOCOCCAL DISEASE. Over 80% of Canadians have acquired natural antibodies against serogroups A, B and C by the age of 20years .The very young have the highest disease risk. In the meningitis belt, incidence is highest among children 5 to 10 years of age. During epidemics in this region, older children, adolescents, and young adults<25 to 30 years old are also affected.

 

4 HEALTH OF TRAVELLER

 

ASPLENIA IS A MAJOR RISK FACTOR. Adults and children >= 2 years of age with functional or anatomic asplenia should be vaccinated regardless of geographic exposure. Complement deficiency is another major risk factor, and immune-suppressing conditions, including HIV infection, may also increase risk.

 

TRAVELLERS NOT NEEDING VACCINE:

 

Vaccination is not routinely recommended for adults who are travelling for < 3 weeks on business or holiday ( including safaris) to areas of heightened meningococal activity if they have little exposure to local populations in crowded situations. When doubt about the nature of exposure exist, it may be prudent to offer vaccine

           

Laboratory-acquired Menningococcal infection is believed to be rare.  Research, industrial and clinical laboratory personnel who are routinely exposed to N. Meningitis should be offered immunization with Quadrivalent Men ACYW-Ps and may be additionally offered Men-C-Consulate vaccine to provide enhanced protection against Serogroup C Meningocaccal infection.

           

Current Canadian guidelines (from the Committee to Advise on Tropical Medicine and Travel) for the prevention of MENNINGOCOCCAL disease in travellers should be consulted.       

Epidemic alerts are published regularly on the following websites;

-www.travax.com

-Travel Medicine program at www.TravelHealth.gc.ca

-WHO:Outbreaks News at www.who.int/emc/index.html

-US Centers for Disease Control and Prevention www.cdc.gov/travel/diseases/menin.htm

 

III        Prevention

                       

First line of defence against any disease is to avoid exposure. Since meningitis is transmitted by direct contact with respiratory droplets from the nose and throat of infected persons, clients should be advised to avoid crowded areas, especially with local population in risk areas.

           

 

Part B           VACCINE

           

Purified Capsular Polysaccharide Vaccines:      

                        -Bivalent AC

                        -Quadrivalent ACYW135

 

I           Composition & Efficacy

 

This vaccine is a freeze-dried preparation of the group-specific Polysaccharide Antigens from Neisseria Meningitis Group A - C - Y - W 135.

The solvent is sterile Ryrocen-free distilled water to which thimerosal C mercury derivate 1 : 10,000 is added as a preservative.

The vaccine when re-constituted is a clear colourless liquid.

 

Data demonstrate lack of efficacy in those under 2 years, poor efficacy in 2-3 year olds and short duration of efficacy of the serogroup C component of Men ACP’s and Men ACYWPs vaccines, particularly in children less than 10 years of age.

 

During a serogroup A epidemic in Africa, the efficiency of Polysaccharide vaccines against Serogroup A was estimated at 87%.  Although protection against Serogroup A conferred by Men AC-p’s or MenACYWP’s vaccine may persist in school-aged children and adults for at least 3 years, the efficiency of the group A vaccine in children aged less than 5 years may decrease markedly within this period.               

 

           

Booster doses and re-immunization

 

The need for Booster, or effectiveness of, re-immunisation with MENNINGOCOCCAL polysaccharide vaccine has not been fully established.

 

REPEATED IMMUNISATION MAY INDUCE IMMUNOLOGIC HYPORESPONSIVENESS TO POLYSACCHARIDES VACCINES ALTHOUGH THE CLINICAL SIGNIFICANCE OF THIS PHENOMENON IS UNKNOWN. Re-immunization should be considered according to the table for those continuously or repeatedly exposed to serogroup A disease who have been previously immunized with MenACYW-Ps or MenAC-Ps, particularly for children initially immunized  �  5 years of age.

           

TABLE 3                   

Recommended interval between repeat doses of MENNINGOCOCCAL Polysaccharide Vaccines in Individuals Repeatedly or Continuously Exposed to Serogroup A Disease

 

Age when first immunized	No. of primary doses	Interval since last dose as indication for repeat dose
3-12 months	2 doses 2-3 month apart	6-12 months
13-23 months	2 doses 2-3 months apart	1-2 year
2-5 years	1 dose	2-3 years
/ 6 years	1 dose	/ 5 years

           

The new MenC-conjugate vaccine is believed to induce immunologic memory that can be demonstrated for at least 5 years after primary immunization. Individuals who have previously received MenACYW-Ps or MenAC-Ps may receive MenC-conjugate vaccine for continued protection against serogroup C MENNINGOCOCCAL disease after primary immunization. Since an adequate response to MenC-conjugate vaccine has been observed with a delay of 6 months after immunization with purified polysaccharide vaccine in adults, this remains the recommended interval until further data are available. In other circumstances, when MenC conjugate vaccine has already been administered and protection against serogroup A, Y or W135 meningococci is required, a period of 2 weeks should elapse before immunization with MenACYW to allow time for generation of an antibody response and avoid possible interference with this response by the polysaccharide vaccine.    

 

II         Contraindication

 

Should be deferred during the course of any acute illness.

Individuals with known sensitivity to thimerosal or any other component of the vaccine.

 

 

III        Precaution (pregnancy, nursing mothers, special conditions)

 

In persons receiving immunosuppressive therapy, the expected immune response may not be obtained. The vaccine is not contraindicated in immunosuppressed individual.

 

Pregnancy: Safety in pregnant women has not been established. It is prudent not to use, unless there is a substantial risk of infection

 

 

IV        Drug interaction

                                                                             

Can be given at the same time as other immunizations if needed.

           

V         Adverse Reactions

 

Local Reactions: Transient local pain sometimes associated with edema or erythema were reported in up to 50% of vaccinee.

 

Systemic Reactions: Fever, headache, allergic-type reactions (urticaria, erythematous rash)

Myalgia, arthralgia, and gastro-intestinal disorders are very rarely observed. Exceptionally more severe hypersensitivity reactions such as anaphylactic were reported. Very rare cases of Neuropathy (parasthesia, meninges, convulsions) were observed.

 

 

Part C        ADMINISTRATION                                                               

 

I           Dose / Route (amount & schedule, booster)

 

MenAC-Ps and MenACYW-PS

 

Single injection 0.5ml. given subcutaneously regardless of age.

           

See Part B  I  Compositing & Efficacy  Table 1  for booster times.

           

 

 

 

MenC-conjugate

MenC-conjugate is administered in Quebec and is recommenced but is not part of children regular immunisation in Canada.

 

Single intramuscular injection of 0.5mL MenC-conjugate for children >1 year of age.

For infants, three doses are given at 2, 4 and 6 months at the same time as the regular primary series of immunization.

Two doses are offered to infants from 4 to 12 months of age who missed the first dose.

                       

Other Meningitis Protein-Polysaccharide conjugate vaccines licenced in Canada;

            -Menjugate, from Chiron Corp. Licenced in 2001.

                        -Neisvac-C, from Shire Biologics. Licenced in 2001

           

 

                       

                                                                                                           

 

 

Storage

Store freeze-dried vaccine and reconstituted vaccine, when not in use at 2E to 8E C. Discard remainder of 10 dose vials of vaccine within 5 days after reconstitution, in Canada.This is for the 10 doses ACYW135.

 

 

 

 

 

References    

1)   Canadian Immunization Guide 2002

2)   Committee to Advise on Tropical Medicine and Travel (1999). Statement on Meningococcal Vaccination For Travellers.

3)   Menomune ACYW-135 Aventis Pasteur (1994) Insert