Dr. Neil Crane is chairman of infectious diseases at Suburban Hospital in Bethesda, Maryland. He graduated magna cum laude from Princeton University and received his medical degree from Washington University School of Medicine in St. Louis, Missouri. He is board certified in internal medicine and infectious diseases and has a medical practice in Chevy Chase, Maryland. A cold is an infection in the nasal passages by one of innumerable viruses, usually rhinoviruses. It is characterized by runny nose, sneezing and sometimes low-grade fever and sore throat.
Influenza is a particular virus in the orthomyxovirus family.
There are two type A influenza viruses, designated H3N2 and H1N1. Unlike the common cold, influenza can affects the lung with a viral pneumonia. It is characterized by fever, cough, muscle aching and a milder runny nose than a cold. These enter the mucous membranes of the susceptible person and cause infection. The illness usually begins 18 to 72 hours after exposure.