Meningococcal  meningititis

Caused by Neisseria meningitides ,vaccine against meningococcal meningitides is polysaccharide vaccines this vaccine containing highly purified high molecular weight capsular polysaccharide of serogroups A,C,Y and W135 are commercially available .they are supplied as lyophilsed monovalent A ,Monovalent C ,divalent  or tetravalent A-C-Y-W135 products .lactose is added to these as stabilization is important for group A polysaccharide otherwise on exposure to ambient temperature it readily gets depolymerised and loses its immunogenicity .The vaccine contains 50 μg of each polysaccharide per dose and are administered subcutaneously

Dose

A single dose 0.5 ml is recommended for all above 24 months of age .Group A vaccine can be given to children of 6 months of age provided a booster is given three months after the first dose .

Immunity

Single dose of the vaccine appears within five days of vaccination and lasts for three years after which booster is mandatory .Revaccination may be done after two years if there is high risk situation

Contraindication

1- Acute febrile illness

2- Current acute or chronic evolving disease

3- pregnancy 4- sever reaction to previously administered meningococcal A and C vaccine

Storage

Though polysaccharide vaccine are comparatively heat stable because of their chemical nature as well as presentation in freeze dried form ,yet it is recommended that for the maintenance of potency throughout the period of validity three years from the date of production  the vaccine should be kept at 2-8 C ordinary refrigerator .the vaccine is marketed as afreeze dried product and divalent can be frozen also .single dose as well as multiple dose 50 doses vials are available  .

Adverse reaction

More than 200 million human being hae been administered the group A and C meiningococcal vaccine without asingle reported fatality or serious permenant squeal .Adverse reaction are limited to local inflammation which may be due to the presence of high level of preexisting antibody or contamination with polysaccharide .LPS if present may some time cause systemic reaction also .in rare instances anaphylaxis has also been reported .

Ddisatvantage of vaccine

The inability of group C vaccine to induce adequate immune response in children less than 24 months old and inability to produce a vaccine against infections with group B meinigococci .

Attempt to enhance the immunogenicity of group B polysaccharide by two approaches have been found to create a formulation with enhanced immunogenicity of group B vaccine .the first was the use of noncovalent complexes of group B capsular polysaccharide and outermembrane proteins

The second in this was chemical modification of the polysaccharide by replaced the N acetyl groups from the polysaccharide with N propionyl group

Apart from developing an effective vaccine against group B Streptococci attempts are also being made to improve the vaccine against group A and C especially efficacy in younger children .the success achieved by coupling Haemophilus influenzae type b vaccine with a carrier molecules  

Limitation of meningococcal vaccine

• low efficacy of vaccine in children less than two years of age
• No role in established nasopharyngeal carriers
• No vaccine available against each serogroups
• Short lived immunity after vaccination
• Time taken for seroconversion is more than average incubation period of the disease

Plaque

Causative agent Yersinia pestis

Vaccine against plaque .All the killed vaccines that are available now a days  are the modified of original Haffkine vaccine .the organism are grown in laboratory and killed with formalin

Composition

The vaccine is suspension of 2000 million organisms per ml and preserved in phenol .the organisms are killed with formalin 0.1%

Dose and route of administration

The adult dose is 0.5 ml given subcutaneously followed by second dose of 1 ml after 7-14 days .boosters are given every six months children are given reduced dosages according to their weight .

Immunity

Appears after 5-7 days of vaccination and lasts around 6 months

Adverse reactions

Vaccination may results in side effects of fever ,headache ,malaise ,lymphadenopathy and erythema and indurations at injection site these reactions are more common after repeated inoculation

Contraintications

• Acute febrile illness
• Known hypersensitivity to beef protein ,soya or phenol
• Persons with history of severe local or systemic reactions to earlier immunization against plaque
• Pregnancy