Rheumatic fever

Rheumatic fever (RF) is a serious inflammatory disease. It affects several different systems in the human body. It can involve the heart, the joints, the skin, and the brain.

This condition typically develops two to four weeks after a person has a throat infection. The infection is caused by a bacterium called Streptococcus pyogenes. If this infection is left untreated, up to three percent of people may develop rheumatic fever. This disease is most common in children between the ages of 5 and 14. However, about 20% of first-time attacks occur in adults.

The underlying cause of the disease is a biological mistake called molecular mimicry. During a Streptococcus pyogenes infection, the immune system produces antibodies to fight the bacteria. The cell wall of these bacteria contains certain proteins, such as M protein, which are highly antigenic. These proteins look very similar to proteins found in human tissues. This similarity causes a type II hypersensitivity reaction. The immune system creates antibodies to attack the bacteria, but these antibodies also attack the body's own tissues. They may react against the myocardium, which is the heart muscle, and the joints.

This immune response causes significant inflammation throughout the body. In the heart, this inflammation can lead to different types of carditis. One form is called "bread-and-butter" pericarditis, which involves a serofibrinous pericardial exudate. When the endocardium is involved, it can result in fibrinoid necrosis. This often leads to the formation of warts along the heart valve closure lines. Doctors can see specific markers of this under a microscope. These are called Aschoff bodies, which consist of swollen collagen surrounded by lymphocytes and macrophages. Some of these larger macrophages may become Anitschkow cells or Aschoff giant cells.

Repeated attacks of rheumatic fever can lead to rheumatic heart disease (RHD). RHD is characterized by permanent damage to the heart valves. This damage occurs through repeated inflammation and fibrinous repair. The valve leaflets may thicken, and the commissures may fuse together. The tendinous cords can also become short and thick. This structural damage can cause valve stenosis, where the valve is too narrow. It can also cause regurgitation, where the valve does not close properly. These damaged valves can eventually lead to heart failure or atrial fibrillation.

Scientists believe that genetics play a major role in who gets the disease. Certain genes on human chromosome 6 increase a person's susceptibility. For example, the HLA-DR7 allele is often associated with RHD. Other factors include the cytokine TNF-α, which can make valve inflammation worse. Variations in the MBL2 gene are also linked to how the disease affects the valves. Some variations are associated with mitral valve stenosis. Other variations are linked to aortic valve regurgitation. These genetic factors combine with environmental risks like malnutrition and poverty.

Medical history shows that humans have known about this condition for a long time. Descriptions of these symptoms date back to at least the 5th century BCE. These early records were written by the physician Hippocrates. The disease is named "rheumatic" because its symptoms resemble other rheumatic disorders. In 1944, Dr. T. Duckett Jones published the Jones criteria. These criteria help doctors diagnose the fever by looking for specific major and minor signs. Today, doctors also use echocardiography to detect heart damage. This is often more efficient than just listening to the heart with a stethoscope.

The impact of this disease on global health is very large. Every year, about 325,000 children develop rheumatic fever. Currently, approximately 33.4 million people live with rheumatic heart disease. The disease is most common in the developing world and among indigenous peoples. In 2015, the disease caused 319,400 deaths worldwide. This was a decrease from 374,000 deaths in 1990. However, in the developing world, as many as 12.5% of affected people may die each year.

Prevention and treatment are the most important ways to manage the disease. Treating a sore throat with antibiotics like penicillin can prevent rheumatic fever from starting. In areas where testing is not available, this is a vital tool. For people who already have rheumatic heart disease, doctors may recommend long periods of antibiotics. In severe cases, surgery may be needed to repair or replace damaged heart valves. Improving sanitation is another way to reduce the spread of the bacteria. After an attack, patients often make a gradual return to their normal activities.