Smallpox : Complications

Arthritis and bone infections; Brain swelling (encephalitis; Death; Eye infections; Pneumonia; Scarring; Severe bleeding; Skin infections (from the sores.

Death from smallpox ranged up to about 35%, with the more severe, hemorrhagic form nearly 100% fatal. Patients who survived smallpox infection nearly always had multiple areas of scarring where each pock had been.

Pneumonia is an infection of the lungs. Many different organisms can cause it, including bacteria, viruses, and fungi. Pneumonia can range from mild to severe, and can even be deadly. The severity depends on the type of organism causing pneumonia, as well as your age and underlying health.

The most common mechanism by which the lung is inoculated with pathogenic organisms is through microaspiration of oropharyngeal contents, a process that occurs in otherwise healthy individuals during sleep ( Chapter 82 ). Colonization of the oral pharynx with pathogenic organisms, such as Streptococcus pneumoniae ( Chapter 303 ), can thereby lead to delivery of sufficient quantities of organisms to infect the lung.

Pneumonia is an infection of the lung, and can be caused by nearly any class of organism known to cause human infections. These include bacteria, viruses, fungi, and parasites. In the United States, pneumonia is the sixth most common disease leading to death . It is also the most common fatal infection acquired by already hospitalized patients. In developing countries, pneumonia ties with diarrhea as the most common cause of death.

Introduction Pneumonia has been recognized as a disease entity since remote times, with definitions of the condition traceable in ancient Greek, Roman, and Arabic writings. Definitive recognition of the etiologic role of microorganisms in pneumonia, and the identification of Streptococcus pneumoniae as the most common causative agent was only achieved roughly 120 years ago.

The actual incidence of pneumonia in ambulatory patients is difficult to estimate because the etiologic agent is rarely identified except in clinical trials, and CAP is not currently considered a reportable disease. Each year in the United States there are 2 to 3 million cases of CAP.

The following Clinical Topic Tour provides an overview of pneumococcal pneumonia and was adapted by materials published by the National Institute of Allergy and Infectious Diseases and the CDC.

Pneumonia is an infection of the lungs that can be caused by nearly any class of organism known to cause human infections, including bacteria, viruses, fungi, and parasites. It results in an inflammatory response within the small air spaces of the lung (alveoli).

Chlamydial pneumonia refers to one of several types of pneumonia that can be caused by various types of the bacteria known as Chlamydia .

Eosinophilic pneumonia is a group of diseases in which there is an above normal number of eosinophils in the lungs and blood.

Pneumococcal pneumonia is a common but serious infection and inflammation of the lungs. It is caused by the bacterium Streptococcus pneumoniae .

Pneumocystis pneumonia is a lung infection that occurs primarily in people with weakened immune systems—especially people who are HIV-positive. The disease agent is an organism whose biological classification is still uncertain. Pneumocystis carinii was originally thought to be a one-celled organism (a protozoan), but more recent research suggests that it is a fungus. Although its life cycle is known to have three stages, its method of reproduction is not yet completely understood. The complete name of the disease is Pneumocystis carinii pneumonia, often shortened to PCP. PCP is also sometimes called pneumocystosis.

Pneumonia is a serious infection of the lung that impairs breathing. Small air sacs in the lung (alveoli) become filled with pus, mucus or other fluid, and cannot supply oxygen to circulating blood . Lobar pneumonia affects one section, or lobe, of the lung; bronchial pneumonia, or bronchopneumonia, affects scattered areas of either lung.

One of the most common pulmonary complications affecting cancer patients, pneumonia is a potentially life-threatening inflammation of one or both lungs.

Pneumonia is an infection of the lung that can be caused by nearly any class of organism known to cause human infections . These include bacteria, amoebae, viruses, fungi, and parasites. In the United States, pneumonia is the sixth most common disease leading to death; 2 million Americans develop pneumonia each year, and 40,000–70,000 die from it. Pneumonia is also the most common fatal infection acquired by already hospitalized patients. In developing countries, pneumonia ties with diarrhea as the most common cause of death. Even in nonfatal cases, pneumonia is a significant economic burden on the health care system. One study estimates that people in the American workforce who develop pneumonia cost employers five times as much in health care as the average worker. According to the Centers for Disease Control and Prevention (CDC), however, the number of deaths from pneumonia in the United States has declined slightly since 2001.

Encephalitis is irritation and swelling (inflammation) of the brain, usually due to infections. See also: Meningitis

Although the word meningitis suggests an inflammation of the meninges only, there is always some involvement of the most superficial parts of the brain that are contiguous to the meninges. Often there are also alterations in the flow of cerebrospinal fluid (CSF).

Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis. When both the brain and spinal cord are involved, the disorder is called encephalomyelitis. An inflammation of the brain's covering, or meninges, is called meningitis .

Encephalitis is an acute inflammatory process that affects brain tissue and is almost always accompanied by inflammation of the adjacent meninges (tissues lining the brain). There are many types of encephalitis, most of which are caused by viral infections. Meningitis is an inflammation of the membranes (meninges) that surround the brain and spinal cord. Meningitis may be caused by many different viruses and bacteria, or by diseases that can cause inflammation of tissues of the body without infection (such as systemic lupus erythematosus). Viral meningitis is sometimes called aseptic meningitis to indicate it is not the result of a bacterial infection.

An inflammatory disease of the brain caused by a virus that either has invaded the brain, or a virus appearing elsewhere in the body that has caused a sensitivity reaction in the brain. Encephalitis infects the brain tissue itself and has serious consequences. Among the many forms of encephalitis are those that occur seasonally, those that affect animals, and a form that is carried by a mosquito. Viruses that have been directly implicated in causing encephalitis include the arbovirus, echovirus, poliovirus, and the herpes simplex virus. Encephalitis occurs as a complication of, for example, chicken pox, polio, and vaccinia, which is a cowpox virus used in smallpox vaccinations, as well as the common flu virus. Other implicated causes include the herpes simplex virus, responsible for the common cold sore, eczema, and genital herpes; the measles (rubeola) virus; some of the 31 types of echoviruses that also cause a paralytic disease or an infection of the heart muscle; the coxsackie virus responsible for infections of the heart and paralysis; the mumps virus; and the arboviruses that normally infect animals and can be spread by mosquito to humans. The virus responsible for encephalitis can invade the cranium and infect the brain via the circulatory system. The blood-brain barrier, a system that protects the brain from certain drugs and other toxins, is ineffective against viruses. Once it has gained entrance into the brain the virus infects the brain tissue. The immediate reaction is an inflammation that causes the brain to swell and activates the immune system. The tightly closed vault of the cranium leaves little room for the brain to enlarge, so when it does expand it is squeezed against the bony skull. This can result in loss of neurons, or nerve cells, which can result in permanent post-infection damage, depending upon the location of the damage. The individual who is developing encephalitis will have a fever, headache, and other symptoms that depend upon the affected area of the brain. He may fade in and out of consciousness and have seizures resembling epileptic seizures. He may also have rigidity in the back of the neck. Nausea, vomiting, weakness, and sore throat are common. Certain viruses may cause symptoms outside the nervous system as well. The mumps virus will cause inflammation of the parotid gland (parotitis), the spleen, and the pancreas as well as the brain, for example. An infection by the herpes virus can cause hallucinations and bizarre behavior. Treatment of encephalitis is difficult. It is important that the type of virus causing the infection be identified. Drugs are available to treat a herpes virus infection, but not others. The death rate can be as high as 50% among patients whose encephalitis is caused by the herpes virus. Infection by other viruses, such as the arbovirus, may have a mortality rate as low as 1%. Reduction of fever, as well as treatment for nausea and headache, is needed. Unfortunately, even those who survive viral encephalitis may have remaining neurologic defects and seizures. Reye's syndrome is a special form of encephalitis coupled with liver dysfunction seen in young children and adolescents. Invariably, children who develop Reye's syndrome have had an earlier viral infection from which they seemingly have recovered. Hours or days later, however, they will begin to develop symptoms such as vomiting, convulsions, delirium, and coma. A virus such as the influenza virus, varicella (measles), and coxsackie virus are responsible. For reasons unknown, giving a child aspirin tablets to reduce fever accompanying a cold or flu can trigger Reye's syndrome. At the time the nervous system begins to show signs of infection, the liver is also being affected. Fatty deposits begin to replace functional liver tissue, and similar fatty tissue can be found in the heart muscle and the kidneys. The relationship between the viral effects on the brain and the parallel liver damage is not known. Treatmen

Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis. When both the brain and spinal cord are involved, the disorder is called encephalomyelitis. An inflammation of the brain's covering, or meninges, is called meningitis .

Arthritis is inflammation of one or more joints, which results in pain, swelling, stiffness, and limited movement. There are over 100 different types of arthritis. See also: Joint pain

A term referring to a variety of conditions characterized by inflammation of one or more joints. Arthritis is commonly regarded as a disease of the elderly, but there are several varieties that primarily affect children, including juvenile rheumatoid arthritis, infectious arthritis, and juvenile ankylosing spondylitis.

Bleeding refers to the loss of blood. Bleeding can happen inside the body (internally) or outside the body (externally. It may occur: Inside the body when blood leaks from blood vessels or organs; Outside the body when blood flows through a natural opening (such as the vagina, mouth, or rectum; Outside the body when blood moves through a break in the skin.

Osteomyelitis is an acute or chronic bone infection, usually caused by bacteria.

Osteomyelitis refers to a bone infection, almost always caused by a bacteria. Over time, the result can be destruction of the bone itself.