Meningococcemia overview

# Overview
Meningococcemia is the presence of Neisseria meningitidis' (also known as meningococcus), a severe bacterial infection, in the blood stream. It is demonstrated by blood culture. The disease is hard to identify as it can appear in several different forms, depending on which part of the body the bacteria invades. Neisseria meningitides is a gram-negative diplococcus. The bacteria is known to cause: meningitis, septicaemia, pneumonia, and even rarely urethritis. Early recognition and treatment of those exposed to meningococcus is extremely important in order to prevent serious illness like shock, DIC, multiorgan failure or death.

# Historical Perspective
Historical reports indicate that meningococci was first reported in 1805. Since then, for more than 2 hundred years, meningococcus has been causing a high degree of morbidity and mortality. It usually appears to be sporadic but reports of outbreak have been reported from different parts of the world, especially in the Sub-Saharan African belt. Outbreak usually happens in closed communities, such as: schools, colleges and prisons.

# Classification
13 serotypes of meningococci have been isolated based on their polysaccharide capsule; they are also classified according to outer membrane protein. Out of these thirteen, five of them cause clinically severe diseases.

# Pathophysiology
Meningococcal infection is caused by Neisseria meningitidis and it spreads through respiratory and throat secretions. Once it gets absorbed by endocytosis into the body, it gets seeded in skin , meninges and other organs; it causes a variety of clinical manifestation from meningitis to septic shock. The meningococcal lipopolysaccharide is an important factor in infection; host factors such as Toll Like Receptor (TLR) and inflammatory cytokines (IL-6) play an important role in the pathogenesis of the disease.

# Causes
Meningococcemia is caused by a bacteria called Neisseria meningitidis. The bacteria frequently lives in a person's upper respiratory tract without causing any visible signs of illness. The bacteria can spread from person to person interaction through respiratory droplets; for example, to be around an already infected individual, during the time that he or she sneezes or coughs, can cause an individual to become infected. Family members and those closely exposed to someone with the condition are at increased risk. The infection occurs more frequently in the winter and early spring.

# Differential Diagnosis
Meningococcemia must be differentiated from other diseases that cause neurological symptoms, such as: brain abscess, encephalitis, delirium tremens, brain tumor, and subarachnoid hemorrhage.  The rash component of meningococcemia must be differentiated from other illnesses causing skin rash, such as: chickenpox, herpes zoster, and erythema multiforme.

# Epidemiology and Demographics
Meningococcus occurs throughout the year, however, the incidence is highest in late winter and early spring. It is the second most common community acquired bacterial infection. The highest incidence worldwide is in Sub-Saharan Africa called meningitis belt. Children are most affected by this disease.

# Risk Factors
Risk factors of meningococcemia include: infants and old age groups ; closed communities; winter and early spring season; complement deficiency; asplenia; and travel to endemic regions, especially to the Sub-Saharan African meningitis belt.

# Screening
Routine screening is not recommended for meningococcemia.

# Natural History, Complications and Prognosis
Neisseria meningitidis bacteria can cause problems ranging from meningitis fatal to septicemia. The symptoms of meningitis appear within 3-7 days of exposure and present with fever and signs of bacterial meningitis. If septicemia occurs, it can be very fatal and the patient dies in few hours. In non fatal conditions they develop disabilities like arthritis, gangrene, Disseminated intravascular coagulopathy and cutaneous vasculitis. The outcome is uncertain in septicemic patients but prognosis is good in non septicemic patients with early intervention and treatment.

# History and Symptoms
Every child with purpuric rash and high fever should be treated as meningococcemia until proven otherwise. The history suggest patient with high fever, rash, headache, myalgia and stiff neck.Non-suppurative pharyngitis is a rare presentation.

# Physical Examination
Physical examination may shows fever, hypotension, petechial rash, conjuctival congestion, nuchal rigidity, seizures, edema, hepatosplenomegaly, dyspnea and rales.

# Laboratory findings
Meningococci is usually identified from blood or CSF analysis. Aspiration or skin biopsy of the rash yield meningococci. CSF analysis usually shows increased protein, low glucose and increased number of neutrophils.

# Medical Therapy
Meningococcemia is a medical emergency and effective antibiotics should be administered promptly to patients suspected of having meningococcal disease. Multiple antimicrobial agents, including penicillins or third generation cephalosporin(eg. Ceftriaxone), are effective against N. meningitidis. Additional therapy may be needed, such as breathing support, fluid resuscitation, and wound care.

# Primary Prevention
Primary prevention of meningococcemia includes vaccination and chemo prophylaxis. There are mainly 2 different types of vaccine namely polysaccharide and conjugate vaccine. Chemoprophylaxis is mainly with rifampin, ceftriaxone, ciprofloxacin and azithromycin.

# Cost-effectiveness of Therapy
Cost effective analysis study has indicated that  a 2-dose series at ages 11 years and 16 years has a similar cost-effectiveness compared with moving the single dose to age 15 years or maintaining the single dose at 11 years.

# Future or Investigational Therapies
Future investigational therapies are showing promising results where 2 new vaccines were being developed against serogroup B and 3 new types of antigen have been found to be useful in making vaccines more potent.