Many people use the terms “cold” and “flu” interchangeably. Though both are respiratory illnesses, their symptoms are different. Medical testing is the only conclusive way to determine if someone has seasonal flu or the H1N1 (swine) flu.
Two strains of flu--seasonal flu and the H1N1 (swine) flu--are currently circulating in the United States. A third, highly lethal H5N1 (Avian) flu is being closely tracked overseas.
Illness Symptom Table
The following table derived from the NIAID and the CDC for H1N1 (swine) flu illustrates the differences between the cold, seasonal flu, and H1N1 (swine) flu in adults:
| Symptoms |
Cold |
Seasonal Flu and H1N1 (Swine) Flu |
| Onset after infection |
2 or 3 days |
1 day, then quickly |
| Fever |
Rare |
Common; starts quickly and lasts 3 or 4 days |
| Headache |
Rare |
Common |
| General aches |
Slight |
Common, often severe |
| Fatigue, weakness |
Sometimes |
Common; can last up to 3 weeks |
| Extreme exhaustion |
Never |
Common; an early symptom |
| Stuffy nose |
Common |
Sometimes |
| Sneezing |
Common |
Sometimes |
| Coughing |
Intermittent |
Sometimes |
| Sore throat |
Common |
Sometimes |
| Chest pain, cough |
Mild; moderate |
Common; can become severe and persistent |
| Lack of appetitie |
Sometimes |
Common |
| Diarrhea |
Rare |
Sometimes; more common with H1N1 |
| Vomiting |
Rare |
Sometimes; more common with H1N1 |
How H1N1 (Swine) and Other Flu Viruses Spread
H1N1 (swine) and other flu viruses spread from person to person when an infected person coughs, sneezes, or touches a surface that is subsequently touched by another person. The flu spreads more readily when people are indoors, where the chances increase for physical contact with contaminated surfaces and inhalation of airborne viral particles. According to the CDC, people infected with the flu are most contagious almost immediately after infection (a day before symptoms develop) and for 5 to 7 days after symptoms initially appeared.
Breathing in flue virus particles is the most common pathway for flu infection. It is also a pathway for cold viruses when infected airborne mucus droplets are inhaled into the nose or throat. Touching surfaces coated with flu virus particles is a common pathway to infection, but inhaling airborne viral particles is more frequent.
Flu viruses are very hardy; they can survive for several hours on surfaces. The common pathway to infection from touching contaminated surfaces is touching the surface with the hands, then touching the nose or rubbing the eyes. The virus enters the tear ducts or sinuses and infects the nasal passage.
Common surfaces that may be contaminated with the flu virus include:
- Door knobs
- Coffee pot handles
- Hands or face of others (a handshake is a significant infection pathway)
- Doorknob or handle (including microwave, refrigerator, and material handling equipment)
- Copier machine buttons or parts
- Coffee pot handle
- Elevator button
- Bathroom fixture
- Countertop
- Food or food container handled by others
- Book or other office materials used by others
- Phone used by others
- Hand or power tool used by others
Additional H1N1 Planning Information