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Meningococcal disease is caused by a bacterium known as Neisseria meningitidis (also
called as meningococci). Twelve serogroups of N. meningitidis have been identified. Of these, group A is
the commonest agent responsible for outbreaks in Asia.
How is the disease
transmitted
The bacteria are transmitted from person to person through
droplets of respiratory or throat secretions. Close and prolonged contact
(e.g. kissing, sneezing and coughing on someone, living in close quarters or
dormitories (military recruits, students), sharing eating or drinking
utensils, etc.) facilitate the spread of the disease. The average incubation
period is 4 days, ranging between 2 and 10 days.
N. meningitidis only
infects humans; there is no animal reservoir. The bacteria can be carried in
the pharynx and sometimes, for reasons not fully known, overwhelm the body’s defences allowing infection to spread through the
bloodstream and to the brain. It is estimated that between 10 to 25% of the
population carry N.meningitidis at any given
time, but of course the carriage rate may be much higher in outbreak
situations.
CLINICAL Features
of the disease
All infected individuals do not develop meningitis. Among
those who develop meningitis, the most common symptoms are stiff neck, high
fever, and sensitivity to light, confusion, headaches and vomiting. Even when
the disease is diagnosed early and adequate therapy instituted, 5% to 10% of
patients die, typically within 24-48 hours of onset of symptoms. Bacterial
meningitis may result in brain damage, hearing loss, or learning disability
in 10 to 20% of survivors.
A less common but more severe (often fatal) form of
meningococcal disease is meningococcal septicemia which is characterized by a
haemorrhagic rash and rapid circulatory collapse.
OUTBREAK CONTROL
STRATEGY
 Early
diagnosis and prompt treatment
The diagnosis of meningococcal disease is suspected on the
clinical presentation. However, diagnosis is confirmed through culture of
cerebrospinal examination obtained on lumbar puncture. The identification of
the serogroups as well as testing of susceptibility to antibiotics can be
carried out in specialized laboratories.
Meningococcal disease has a high case-fatality rate and is
therefore potentially fatal. Cases with meningitis should be invariably
hospitalized. Early recognition and
prompt treatment can prevent serious illness or death. Admission to a
hospital or health centre is necessary. As the disease is spread through
droplets (and in crowded and congested situations), adequate spacing and good
ventilation need to be considered, although strict isolation of the patient
may not be necessary. Antimicrobial therapy must be commenced as soon as
possible after the lumbar puncture has been carried out (if started before,
it may be difficult to grow the bacteria from the spinal fluid and thus
confirm the diagnosis). A range of antibiotics may be used for treatment
including penicillin, ampicillin, chloramphenicol, and ceftriaxoneMeningococcal
disease has a high case-fatality rate and is therefore potentially
fatal. Cases with meningitis should be invariably hospitalized. Early recognition and prompt treatment
can prevent serious illness or death. Admission to a hospital or health
centre is necessary. As the disease is spread through droplets (and in
crowded and congested situations), adequate spacing and good ventilation need
to be considered, although strict isolation of the patient may not be
necessary. Antimicrobial therapy must be commenced as soon as possible after
the lumbar puncture has been carried out (if started before, it may be
difficult to grow the bacteria from the spinal fluid and thus confirm the
diagnosis). A range of antibiotics may be used for treatment including
penicillin, ampicillin, chloramphenicol,
and ceftriaxone.
Vaccination
Several vaccines are available to prevent the disease.
Polysaccharide vaccines, which have been available for over 30 years, exist
against serogroups A, C, Y, and W135 in various combinations. All these
vaccines have been proven to be safe and effective with infrequent and mild
side effects. The vaccines may not provide adequate protection for 10
to 14 days following injection.
Routine vaccination: Routine preventive mass
vaccination has been attempted and its effect has been extensively debated. Saudi Arabia,
for example, offers routine immunization of its entire population. Sudan and
other countries (to prevent frequent outbreaks) routinely vaccinate school
children. Preventive vaccination can also be used to protect individuals at
risk (e.g. travellers, military, pilgrims).
Protection of close contacts: When a sporadic case
occurs, the close contacts need to be protected by a vaccine and
chemoprophylaxis with antibiotics to cover the delay between vaccination and
protection (as the vaccines may not provide adequate protection for 10-14
days following injection).
Vaccination for outbreak control: Since even large
scale coverage with current vaccines does not provide sufficient “herd
immunity”, the current WHO recommendation for outbreak control is to mass
vaccinate every district that is in an outbreak phase, as well as those
contiguous districts that are in alert phase. It is estimated that a mass
immunization campaign, promptly implemented, can avoid 70 % of cases.
However, decisions on geographic extent of mass
vaccination coverage need to be evaluated on a case-by-case basis taking into
account all epidemiological and laboratory information, assessed risk for
spread, and resources available.
Chemoprophylaxis
Chemoprophylaxis for close contacts with appropriate
antibiotics is effective in not only preventing but also reducing carrier
state. Antibiotics used for chemoprophylaxis are ciprofloxacin, rifampicin, minocycline, spiramycin, and ceftriaxone.
Risk
communication
Communities can play critical role in containment of
outbreak and protection of individuals. The risk factors and possible control
strategies should be communicated to them by the health authorities and
communities in turn should Implement prevention and control measures as advised
by Public Health Officials. Risk factors like overcrowding can be avoided by
the communities and immediate medical care can be sought by early recognition
of the signs and symptoms of the disease in any family member. The
surveillance and notification of cases in the community can also be
facilitated by the cooperation of the communities.
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