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Respiratory Tract Infections: How to Tell Cold or Flu Symptoms from Inhalational Anthrax

What are the symptoms of a cold?

If you have a cold, you can have any or all of these symptoms: increased nasal discharge (a runny nose), difficulty breathing through the nose, sneezing, a scratchy throat, and cough. The ability to taste and to smell may be affected, hoarseness may develop, and the voice often develops a nasal quality. Adults may experience a slight fever, while infants and young children may develop a higher temperature. The symptoms of the average cold last about one week. However, in roughly one out of every four cases, the illness lasts up to two weeks. In general, cold symptoms, especially the cough, tend to be worse among smokers.

What are the symptoms of influenza (often called "flu")?

Flu symptoms are often more severe than cold symptoms. If you have the flu you can have any or all of these symptoms: fever, muscle aches, headache, lack of energy, a dry cough, sore throat, and possibly a runny nose. The fever that occurs with flu is usually higher than that with a cold (often > 101o F). Symptoms may last for several days for most people; however, they can last for as long as two weeks. People with lung disease or weakened immunity and the elderly are prone to severe, and possibly fatal complications, from the flu.

What are the symptoms of the inhalation form of anthrax?

Anthrax is a very rare infection. The earliest symptoms of the inhalation (breathing) form of anthrax are mild and not specific; they include fever, tiredness, lack of energy, and mild cough or chest pain. After several days, the symptoms progress to very high fever, shortness of breath, severe breathing difficulties, chest pain, and shock. Symptoms of sore throat, runny nose, or watery eyes are not seen in anthrax.

How do I know that my cold or flu symptoms are not caused by the inhalation form of anthrax?

Symptoms of sore throat, runny nose, or watery eyes are typical for the onset of a cold, not anthrax. Illnesses that begin with these types of symptoms will not "turn into" anthrax.

Some respiratory tract illnesses begin with symptoms commonly referred to as "flu-like" symptoms. These include fever, non-productive cough, lack of energy, and muscle aches. With flu, these symptoms improve after a few days. With the inhalation form of anthrax, the symptoms would worsen rapidly, with development of shortness of breath, chest pains, and increasing fever and chills.

Another clue that a respiratory tract infection is due to a cold or flu is that these types of infections are very contagious, and can be spread from person-to-person. Anthrax is not contagious. Therefore, if family members and co-workers have recently recovered from a respiratory tract infection, it is likely to have been a cold or flu.

If I have cold or flu symptoms, when should I call my doctor?

If you have a cold, you will get better, with or without medication, within a few days to two weeks. Sometimes, cold viruses can affect the lining of the upper respiratory system in a way that leads to other infections, such as sinusitis, ear infections or bronchitis. If your cold symptoms get continually worse, or do not resolve over time, you should consult with a physician.

Influenza can also lead to complications. The most serious complication of influenza is pneumonia, which is an infection of the lungs. Pneumonia can be caused by the influenza virus itself, or by bacteria that enter the lungs because the body's natural defenses have been weakened.

Patients with cold or flu symptoms should consult a physician for any of the following symptoms:

  • Persistent high fever
  • Severe headache
  • Shortness of breath
  • Confusion
  • Chest pain
  • Extreme weakness or dizziness
  • Sinus pain or a toothache
  • Ear pain
  • A cough which gets worse, rather than better, as other cold or flu symptoms improve

Are there laboratory tests that can tell if my symptoms are due to flu, or some other respiratory tract infection?

There are laboratory tests that can be used to prove that a person has flu. These tests are available in most hospitals and clinics, and sometimes, in private doctors' offices. Results of these tests may take several hours to several days to become available. There is no screening test available to detect anthrax disease in asymptomatic or minimally symptomatic persons. Nasal swab cultures are not used to diagnose anthrax infection, nor can they predict if some one will come down with the disease in the future.

Does CDC recommend getting an influenza immunization (flu shot) to reduce the number of flu-like illnesses that may be confused with anthrax-related illness?

No. CDC does not recommend that influenza vaccination be considered as a way to avoid confusing influenza disease with suspected anthrax illness, for several reasons:

  • Many other infectious agents (including anthrax) can cause illnesses that begin with flu-like symptoms (fever, body aches, and headaches). Most flu-like illnesses are not caused by influenza (or anthrax).
  • The flu shot can prevent 70-90%, but not all, influenza infections. The vaccine does not prevent flu-like illness caused by agents other than influenza.
  • Influenza vaccine should be targeted toward groups that are at increased risk of complications and toward health care workers. High-risk groups include people with certain chronic medical conditions, and the elderly who are at risk for developing serious complications from influenza. CDC recommends that people in one of these groups be given priority to receive vaccine earliest in the flu season.
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