Rheumatic fever is a serious inflammatory disease that can develop after a streptococcal throat infection. It primarily affects children and young adults, especially in regions where access to medical care is limited. This condition can lead to long-term complications, particularly in the heart, joints, and nervous system. Understanding the causes of rheumatic fever is essential for prevention and effective treatment, as the disease stems from a complex interplay between bacterial infection and the body’s immune response.
What Triggers Rheumatic Fever?
The root cause of rheumatic fever is an infection with a specific type of bacteria called Group A Streptococcus (GAS). This bacterium is responsible for causing strep throat and, less commonly, skin infections. If untreated or inadequately treated, the immune system’s response to this bacterial infection can lead to rheumatic fever.
Group A Streptococcal Infection
The initial event leading to rheumatic fever is an infection with Group A Streptococcus. This bacterium spreads easily through respiratory droplets when an infected person coughs or sneezes. Strep throat symptoms include sore throat, fever, headache, and swollen lymph nodes. If the infection is not promptly treated with antibiotics, the bacteria can trigger an abnormal immune response.
Immune System Reaction and Molecular Mimicry
The body’s immune system normally attacks invading pathogens like bacteria. However, in rheumatic fever, a process called molecular mimicry causes the immune system to mistakenly attack its own tissues. Certain proteins on the surface of Group A Streptococcus closely resemble proteins found in human tissues, such as those in the heart, joints, skin, and brain. The immune system creates antibodies targeting the bacterial proteins but inadvertently cross-reacts with the body’s own cells.
Risk Factors That Increase the Likelihood of Rheumatic Fever
While the bacterial infection is necessary for rheumatic fever to occur, several factors make some individuals more vulnerable to developing the disease.
Inadequate Treatment of Strep Throat
Failure to treat streptococcal infections properly is the leading risk factor. Delayed or incomplete antibiotic therapy allows the bacteria to persist and increases the risk of rheumatic fever. Early diagnosis and full adherence to antibiotic treatment are crucial for prevention.
Age and Socioeconomic Factors
Rheumatic fever mainly affects children between 5 and 15 years old. This age group is more prone due to frequent exposure in school settings and developing immune systems. Moreover, the disease is more common in overcrowded living conditions and areas with limited access to healthcare, often correlated with lower socioeconomic status.
Genetic Susceptibility
Research suggests that some individuals have a genetic predisposition that increases their risk. Specific human leukocyte antigen (HLA) types have been linked to a higher likelihood of developing rheumatic fever after streptococcal infection. This genetic susceptibility influences how the immune system reacts to the bacteria.
Pathophysiology How Rheumatic Fever Develops
After a streptococcal throat infection, the immune system produces antibodies to fight the bacteria. In susceptible individuals, these antibodies cross-react with the body’s own tissues, leading to inflammation and tissue damage.
Inflammation of the Heart (Carditis)
One of the most serious consequences of rheumatic fever is inflammation of the heart, particularly the valves. This condition, called rheumatic carditis, can cause permanent damage, leading to rheumatic heart disease. The inflammation affects the mitral and aortic valves, potentially resulting in valve stenosis or regurgitation.
Joint Inflammation (Arthritis)
Rheumatic fever often causes painful inflammation in the large joints such as knees, ankles, elbows, and wrists. This arthritis is typically migratory, affecting different joints at different times, and usually resolves without lasting damage.
Nervous System Effects (Sydenham’s Chorea)
In some cases, the immune reaction affects the brain, causing Sydenham’s chorea. This neurological disorder is characterized by involuntary movements, muscle weakness, and emotional instability.
Environmental and Social Factors Influencing Rheumatic Fever Incidence
Besides the bacterial cause and individual susceptibility, environmental and social conditions significantly impact the occurrence of rheumatic fever worldwide.
Overcrowding and Poor Hygiene
Living in crowded environments facilitates the spread of Group A Streptococcus through respiratory droplets. Poor hygiene and lack of sanitation contribute to the persistence and transmission of the bacteria within communities.
Limited Access to Healthcare
In many developing countries, limited access to medical care delays diagnosis and treatment of strep throat infections. This delay increases the risk that untreated infections will progress to rheumatic fever.
Seasonal Patterns
Rheumatic fever cases tend to increase during colder months when respiratory infections are more common. This seasonal trend reflects the increased transmission of streptococcal bacteria in winter.
Preventing Rheumatic Fever by Addressing Its Causes
Understanding the causes of rheumatic fever enables effective prevention strategies that focus on timely treatment and reducing transmission.
Early Diagnosis and Antibiotic Treatment
Prompt identification and full treatment of streptococcal throat infections with antibiotics such as penicillin prevent the development of rheumatic fever. Completing the full course of antibiotics is essential to eradicate the bacteria completely.
Improving Living Conditions
Reducing overcrowding, improving hygiene, and increasing access to healthcare play a critical role in preventing the spread of streptococcal infections. Public health initiatives targeting these social determinants can significantly lower rheumatic fever rates.
Regular Screening and Follow-up
For people who have had rheumatic fever, regular medical follow-up and prophylactic antibiotics help prevent recurrence and further heart damage.
Rheumatic fever is caused by an abnormal immune response to a Group A Streptococcus infection, particularly strep throat. While the bacterial infection is the essential trigger, multiple factors such as inadequate treatment, age, genetics, and environmental conditions influence who develops this disease. Prevention relies heavily on early diagnosis and complete antibiotic treatment of streptococcal infections, along with public health efforts to reduce transmission. By addressing these causes and risk factors, healthcare systems can decrease the burden of rheumatic fever and its long-term complications on affected populations.