Meningococcemia: Epidemiology & Prevention Baylor College of Medicine Med-Peds Continuity Clinic Anoop Agrawal, M.D.

The Cause: N. Meningitidis Neisseria meningitidis is a commensal bacteria of the human nasopharynx, its only reservoir. Gram negative, aerobic, diplococcus with a polysaccharide capsule 5% to 15% of adolescents and young adults are asymptomatic carriers vs. <2% in young children.

Epidemiology of Disease Rate of disease in US: 1.5 cases per 100,000 Incidence peaks in late winter and early spring Highest risk groups: infants less than 1 year of age and adolescents Most carriers develop protective antibodies to the organism.

Annual incidence of meningococcal disease, US., MMWR, Jan 2011/60(03);72-76

Epidemiology Continued Thirteen serogroups exist, but five serogroups account for majority of invasive disease: A, B, C, Y, W-135 The subtype causing disease varies over time and by geographic location. Subtype A was a common cause in US till WW II. Now is the major cause in sub- Saharan Africa (aka the”meningitis belt”). Currently, B, C and Y are major causes in US.

In 2001, 65% of cases in infants age 1 year or younger were caused by subtype B. Presently, none of the meningitis vaccines offer protection for subtype B.

Pathogenesis Transmission occurs by droplet aerosolization or direct contact with secretions. The bacteria must then cross mucosal barrier and gain access to the bloodstream - virulence factors and host defense mechanisms will determine the development of disease Crowded living conditions, exposure to tobacco smoke are known risk factors.

Disease Outcomes Majority of cases manifested as meningitis (49%), followed by bacteremia (33%) and pneumonia (9%). Case fatality rate of 10% to 14% Up to 20% will have serious sequale: neurologic deficits, deafness, or limb loss.

Primary Prevention Meningococcal Vaccines - What are the two types available? MPSV4 (polysaccharide) MCV4 (conjugate) Menactra (sanofi pasteur) Menveo (Novartis)

The Vaccines MCV4MPSV4 Licensed2005/ Ages approved2-55 years2 or greater SerotypesA, C, Y, W-135 RouteIMSQ Duration of protection Unknown, longer than MPSV 3-5 years Herd ImmunityYesNo

Mortality Which disease has the highest mortality? a. meningitis b. bacteremia c. pneumonia Which age group has the higher mortality? a. infants b. adolescents

Other advantages Conjugate vaccines can be boosted at a later date. MCV-4 can eliminate carrier state. MPSV-4 vaccine has decreased immune responsiveness to subsequent vaccinations.

MCV4 (conjugate) What are the recommendations for use of this vaccine for adolescents? What other persons are considered high risk and should also be vaccinated?

MCV4 Vaccination Rec’s Adolescents: Should be administered as part of routine preventive visit at years of age Booster dose at age 16 years Any adolescent requesting to reduce their risk by vaccination.

Other groups that need vaccination: College freshman living in dormitories Microbiology lab personnel Military recruits Travelers headed to areas of high endemic disease Persons with anatomic or functional asplenia, or terminal complement deficiencies

Why is a booster dose now needed? MCV-4 was expected to provide protection for persons age16 through 21 years with single administration at age 11 or 12 years. Recent data indicate many adolescents might not be protected for more than 5 years.

Case 1 An 16 year old girl presents to your office requesting the MCV4 vaccine. She just found out she is pregnant. Can she receive the vaccine? YES. Does she need a booster following today’s vaccination? No. Persons who receive first dose at or after age 16 years do not need a booster.

Case 2 An 5 year old girl with a history sickle cell and asplenia since the age of 20 months presents for a well child exam. She received the her initial MCV-4 vaccination with a booster 8 weeks later at the age of 2 years. Does she need any further boosters for MCV-4? YES. Children whose previous booster was before their 7th birthday need boosters every 3 years. After the 7 years of age, vaccinations should be given every 5 years.

Case 3 An 17 year old girl with h/o HIV presents to your office for her annual physical. She has never received MCV-4. What is the vaccination schedule for her situation? For children and teens ages years with HIV, give 2 doses at least 8 weeks apart.

Case 4 An 60 year old physician is planning a vacation to northern Nigeria in January. Does this person need vaccination for meningococcal disease? If so, what will you administer? Yes, vaccination is needed. MPSV-4 is the only option for adults older than 55 years of age.

Case 5 An 16 year old girl presents to your office for routine physical. According to her vaccination record, she received MCV-4 at age 13. When can she receive her booster dose? Now. If primary dose was given at age years, then booster can be given between age years. Reasoning: adolescents aged 14 and up are less likely to visit the doctor

Summary N. Meningitidis is found in 5-15% of asymptomatic adolescents. The new MCV4 is recommended for all adolescents beginning at age 11 with a booster at age 16 years. MCV-4 has now been approved to age It protects against 2 of the 3 most common serotypes in US - C and Y, but does not protect against B. MPSV4 may be used if MCV4 is unavailable.