Influenza is an acute disease with a rapid onset and pronounced symptoms. After the influenza virus invades a person’s body, an incubation period of one to two days passes before symptoms appear. Classic symptoms include sore throat, dry cough, stuffed or runny nose, chills, fever with temperatures as high as 39º C (103º F), aching muscles and joints, headache, loss of appetite, occasional nausea and vomiting, and fatigue. For most people flu symptoms begin to subside after two to three days and disappear in seven to ten days. However, coughing and fatigue may persist for two or more weeks.
Death from influenza itself is rare. But influenza can aggravate underlying medical conditions, such as heart or lung disease. Invading influenza viruses produce inflammation in the lining of the respiratory tract, damage that increases the risk that secondary infections will develop. Common complications include bronchitis, sinusitis, and bacterial pneumonia, occurring most frequently in the elderly, people on chemotherapy, and people with acquired immunodeficiency syndrome (AIDS) or another disease that compromises the immune system. If properly treated, these complications seldom are fatal.
Because influenza is so common and exhibits standard symptoms, doctors often diagnose the illness based on the season and whether flu cases have recently been reported in the area. To prove a diagnosis of influenza in a patient, the virus must be isolated from the person’s nasal or cough secretions or blood and identified under a microscope.
Death from influenza itself is rare. But influenza can aggravate underlying medical conditions, such as heart or lung disease. Invading influenza viruses produce inflammation in the lining of the respiratory tract, damage that increases the risk that secondary infections will develop. Common complications include bronchitis, sinusitis, and bacterial pneumonia, occurring most frequently in the elderly, people on chemotherapy, and people with acquired immunodeficiency syndrome (AIDS) or another disease that compromises the immune system. If properly treated, these complications seldom are fatal.
Because influenza is so common and exhibits standard symptoms, doctors often diagnose the illness based on the season and whether flu cases have recently been reported in the area. To prove a diagnosis of influenza in a patient, the virus must be isolated from the person’s nasal or cough secretions or blood and identified under a microscope.
