The swine flu, or H1N1, is an influenza virus. It occurs year-round, although most cases occur from late fall to early spring. It is transmitted from person to person by aerosolized droplets when coughing or sneezing. Swine flu tends to affect children and young adults more seriously than other types of flu, which usually affect the very old or the very young.
General Symptoms
Patients with the swine flue feel tired and fatigued and suffer from body aches and weakness. Most patients have a fever, which can progress to chills. Fever can also cause delirium and a change in mental status. Patients also have vomiting and diarrhea, which can lead to dehydration and kidney failure. These in turn can cause problems with electrolyte balance, for example, serum sodium that is too high or too low.
Electrolyte imbalances can cause kidney problems, seizures, and cardiac rhythm abnormalities. Another common symptom of influenza is myositis, or inflammation of muscles. This can lead to rhabdomyolysis, or breakdown of the muscle cells into metabolic products than can clog the kidneys and cause renal failure.
Respiratory Symptoms
The main symptoms of swine flu involve the respiratory system. Patients usually start with upper-respiratory symptoms of runny or stuffy nose and sore throat. Patients can develop cough and respiratory distress, with rapid breathing and use of accessory breathing muscles, such as the chest and abdominal muscles, resulting in chest wall retractions. Occasionally, patients can develop croup, a narrowing of the upper airway that manifests as stridor, a high-pitched choking noise that happens on inspiration of air. Patients with swine flu can also develop pneumonia, either caused by the virus itself or by a superimposed bacterial infection.
Neurological Symptoms
The swine flu is notable for causing neurological problems. The influenza virus can cause encephalopathy, which can present as seizures, changes in mental status and even coma and death. Status epilepticus, a condition of prolonged and intractable seizure activity, can also occur.
References
- Centers for Disease Control and Prevention
- Red Book: 2009 Report of the Committee on Infectious Diseases, American Academy of Pediatrics, 2009
