Re: Should Fever Be the Main Screening Tool in School H1N1 Decision Making?
The lack of a fever is why fever scans at borders don't do much and why H1N1 will spreads in schools, because most of those infected won't have a fever, and will assume they DON'T have swine flu and will come to school.
The frequency of H1N1 infected patients without a fever is MUCH higher than 10-40%. Mexico initially reported 30%, but most physicians associate fever with flu, so most who were infected but didn't have a fever weren't tested. Milder cases don't even call a doctor becasue the illness is mild and they don't have a fever (and they recover without seeing a doctor). Of those that do see a doctor, many or most are not tested because they don't have a fever. Outbreaks in Chile were later, so they tested more patients with no fever (because of data from Mexico and other reports of lab confirmed infections with no fever) and the frequency rose to 50%. In the US the CDC uses fever in their case definition, so most who are infected but have no fever are not tested. The 93% fever is pure artifact. Even when fever is part of the case definition, 7% don't have a fever.CDC says, "If influenza severity increases, schools should consider instituting active fever and respiratory infection symptom screening of students and staff when they arrive at school. At the beginning of the school day, all students and staff should be asked about suggestive symptoms such as fever, cough, runny nose, and sore throat during the previous 24 hours. Some persons with laboratory-confirmed influenza do not have a fever (between 10% and 40% of people). Therefore, absence of fever does not indicate absence of infection."
http://www.cdc.gov/h1n1flu/schools/technicalreport.htm
The lack of a fever is why fever scans at borders don't do much and why H1N1 will spreads in schools, because most of those infected won't have a fever, and will assume they DON'T have swine flu and will come to school.


