Meningococcal disease

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis (also termed meningococcus). It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can also result in sepsis, which is an even more damaging and dangerous condition. Meningitis and meningococcemia are major causes of illness, death, and disability in both developed and under-developed countries. There are approximately 2,600 cases of bacterial meningitis per year in the United States, and on average 333,000 cases in developing countries. The case fatality rate ranges between 10 and 20 percent. The incidence of endemic meningococcal disease during the last 13 years ranges from 1 to 5 per 100,000 in developed countries, and from 10 to 25 per 100,000 in developing countries. During epidemics the incidence of meningococcal disease approaches 100 per 100,000. Meningococcal vaccines have sharply reduced the incidence of the disease in developed countries. The disease's pathogenesis is not fully understood. Neisseria meningitidis colonises a substantial proportion of the general population harmlessly, but in a very small percentage of individuals it can invade the bloodstream, affecting the entire body, most notably limbs and brain, causing serious illness. Over the past few years, experts have made an intensive effort to understand specific aspects of meningococcal biology and host interactions; however, the development of improved treatments and effective vaccines is expected to depend on novel efforts by workers in many different fields. While meningococcal disease is not as contagious as the common cold (which is spread through casual contact), it can be transmitted through saliva and occasionally through close, prolonged general contact with an infected person. Meningococcemia, like many other gram-negative blood infections, can cause disseminated intravascular coagulation (DIC), which is the inappropriate clotting of blood within the vessels. DIC can cause ischemic tissue damage when upstream thrombi obstruct blood flow and haemorrhage because clotting factors are exhausted. Small bleeds into the skin cause the characteristic petechial rash, which appears with a star-like shape. This is due to the release of toxins into the blood that break down the walls of blood vessels. A rash can develop under the skin due to blood leakage that may leave red or brownish pinprick spots, which can develop into purple bruising. Meningococcal rash can usually be confirmed by a glass test in which the rash does not fade away under pressure. Meningococcal meningitis is a form of bacterial meningitis. Meningitis is a disease caused by inflammation and irritation of the meninges, the membranes surrounding the brain and spinal cord. In meningococcal meningitis this is caused by the bacteria invading the cerebrospinal fluid and circulating through the central nervous system. Sub-Saharan Africa, the Americas, Western Europe, the UK, and Ireland still face many challenges combating this disease. As with any gram-negative bacterium, N. meningitidis can infect a variety of sites. Meningococcal pneumonia can appear during influenza pandemics and in military camps. This is a multilobar, rapidly evolving pneumonia, sometimes associated with septic shock. With prompt treatment, the prognosis is excellent. Another alternative is dexamethasone with vancomycin and meropenem. Pericarditis can appear, either as a septic pericarditis with grave prognosis or as a reactive pericarditis in the wake of meningitis or septicaemia.