Influenza ( flu ) Custom Search Influenza also called flu is a viral infection that can spread rapidly causing epidemics and pandemics. To know more about the H1N1 flu please go to Swine flu. There are three types of the influenza virus. The virus spreads through air containing droplets of respiratory secretions. A unique feature of this virus is its ability to undergo mutation leading to antigenic variation. There is no cross immunity between the 3 types. A and B viruses cause epidemics. Antigenic variation is common in type A. because of the variation it is difficult to develop a vaccine which can prevent all infections. Two types of antigenic variation are seen. One is sudden and major. This is called shift. When the change occurs gradually it is called drift. Antigenic variations are less common is type B. type C virus is stable and does not undergo any change. The virus can be found in secretions of nose and throat for about 2 days before and 2 days after the onset of symptoms. Symptoms and sign: The disease causes sudden onset of high fever, body ache, chills, headache, cold cough and sore throat. Vomiting and diarrhea are common in younger children. Some children may develop a rash. Acute illness lasts for about 2-5 days. Some children have cough and fatigue for several weeks. Complications: Secondary bacterial infection of ear, sinuses or lungs can occur. Reye’s syndrome which manifests as persistent vomiting and alteration in brain function (irritability drowsiness or coma) is another complication. The virus can invade the brain causing encephalitis. Viral pneumonia can occur especially in children with weak immune system. Laboratory findings: The virus may be demonstrated in secretions of the respiratory tract by florescent antibody staining of nasal or pharyngeal epithelial cells. But this test if not available in all laboratories. Antibodies may be detected in the blood but only after a few days. A single reading is not of much valve as antibodies can be detected even in those not suffering from the disease. A rising titer is helpful. Treatment: Antivirals are beneficial if begun within 48 hours after onset of disease. Supportive treatment is directed at fever and prevention of dehydration. Antibiotics may be required for bacterial super infection. Custom Search
Page last reviewed on 2nd January 2011
|
