Invasive meningococcal disease (IMD) is a severe bacterial infection caused by meningococci (Neisseria meningitidis) – most often serogroups A, B, C, less often Y and W. It can lead mainly to meningitis and/or sepsis (septicemia).
How infection occurs: most often by airborne droplets and through contact with respiratory tract secretions/saliva (e.g., close contact, kissing, sharing dishes, staying in crowded places).
Source of pathogen (reservoir): exclusively humans – sick people and asymptomatic carriers (often adolescents and young adults).
Portal of entry: usually nasopharynx.
Incubation period: 2–10 days (most often 3–4 days).
Who is most at risk:
children < 5 years old,
adolescents and young adults (approx. 15–24 years old),
people 65+,
people with reduced immunity,
people staying in clusters (e.g., dormitories, boarding schools, barracks, kindergartens, shelters, mass events/pilgrimages),
smokers and people after recent respiratory infection.
2. Symptoms of invasive meningococcal disease
IMD can develop very quickly. Some cases have a fulminant course – severe condition and even death can occur within 1–2 days from the onset of illness.
Most common symptoms (meningitis / sepsis):
sudden high fever (often paroxysmal),
severe headache,
stiff neck,
nausea and vomiting,
sensitivity to light,
confusion, drowsiness, disturbances of consciousness,
symptoms of sepsis: rapid breathing, very severe weakness, muscle/joint pain, chills, cold hands and feet,
hemorrhagic/petechial rash (dark red/purple spots that may merge).
necrosis of skin/limbs (sometimes necessity of amputation),
failure of kidneys and other organs,
death (even despite rapid treatment).
When to urgently see a doctor / go to ER:
high fever with severe headache and/or stiff neck,
petechial/hemorrhagic rash (especially when it does not fade under pressure),
rapid deterioration of condition, confusion, drowsiness "unable to wake up",
symptoms of sepsis: very rapid breathing, extreme weakness, cold limbs, chills,
disturbing symptoms in small children (apathy, inconsolable crying, excessive sleepiness, vomiting).
3. Where does invasive meningococcal disease occur?
Meningococcal disease occurs all over the world.
Highest risk of epidemic: Sub-Saharan Africa, Sahel zone – so-called "meningitis belt", especially in the dry season (roughly from November/December to June).
Saudi Arabia: epidemics have been recorded (including serogroup W), especially among pilgrims.
Western Europe and North America: outbreaks associated with serogroup C are more common.
In temperate climates, cases occur more often in winter and spring.
This information is particularly important for people planning trips to Sub-Saharan Africa, pilgrimages, and trips involving large gatherings of people (festivals, dormitories, barracks).
4. How to protect yourself against invasive meningococcal disease?
A. General prevention
avoid close contact with people showing symptoms of infection,
in the season of illness and in crowded places: limit risky exposures (crowds, long stays in closed rooms),
do not share drinks, food, cutlery; take care of hand hygiene,
after contact with a confirmed IMD case – urgent contact with a doctor (chemoprophylaxis may be needed for people from close contact).
B. Vaccination (key prevention)
In practice, there are two main directions of protection:
vaccination against meningococci ACWY (conjugated vaccines, quadrivalent),
vaccination against meningococci B (separate preparations).
Type of vaccines (examples of available preparations):
ACWY (conjugated): Nimenrix, Menveo, MenQuadfi,
B (monovalent): Bexsero, Trumenba,
(additionally, there are vaccines only for C, e.g., NeisVac-C).
For whom are they particularly recommended:
people from risk groups (small children, adolescents/young adults, people 65+, reduced immunity),
people living/studying/working in communities (dormitory, boarding school, barracks),
travelers to areas with higher risk (e.g., meningitis belt in Africa),
pilgrims to Saudi Arabia (Hajj/Umrah).
Vaccination schedule (generally – depends on age and preparation):
ACWY: in older children, adolescents, and adults usually 1 dose. In the youngest children, the schedule may include more than 1 dose (depending on age).
MenB: most often 2 doses (interval depends on preparation and age); in some situations, a 3-dose schedule is possible (e.g., for people with higher risk – doctor's decision).
Booster doses and protection time:
immunity after vaccination usually lasts several years (a range of approx. 4–10 years is often given, depending on the vaccine and age at the time of vaccination).
in people with persistent high risk, a doctor or pharmacist may consider a booster dose; entry requirements of the country (certificate) may also be significant.
When to get vaccinated before travel:
it is recommended to take the dose/dose completing the schedule at least 2 weeks before travel, and practically it is worth having a buffer of time (especially if 2 doses of MenB are needed).
Entry requirements (Saudi Arabia):
for pilgrims going to Mecca, quadrivalent ACWY vaccination is mandatory and requires proof of vaccination.
5. Summary
Invasive meningococcal disease is an infection that can develop very rapidly and lead to sepsis or meningitis. Vaccination is one of the most effective methods of protection – especially in small children, adolescents and young adults, people with reduced immunity, and people staying in large clusters. Before traveling (especially to Sub-Saharan Africa or on a pilgrimage), it is best to plan vaccination in advance – minimum 2 weeks, and in the case of multi-dose schedules, correspondingly earlier.