Q&A: Learn the difference between anthrax and flu
March 1, 2002
Q&A: Learn the difference between anthrax and flu
Q. Influenza and inhalation anthrax can have similar symptoms. Does the Centers for Disease Control and Prevention (CDC) recommend getting a flu shot to help diagnose anthrax?
A. A person should get a flu shot only to prevent the flu. CDC does not recommend a person get the flu shot so doctors can tell whether the patient has the flu or anthrax. Many illnesses (including anthrax) begin with flu-like symptoms, which include fever, body aches, tiredness, and headaches. In fact, most illnesses with flu-like symptoms are not the flu or anthrax. Using the flu vaccine is the best way to prevent the flu and its severe complications, especially among those who are at the highest risk (e.g., people older than 65 years old or younger people with chronic disease such as diabetes or heart disease). The flu shot can prevent 70% to 90% of flu infections, but it will not prevent illnesses with flu-like symptoms caused by anything other than influenza.
Q. Is there a way to distinguish between early inhalational anthrax and flu?
A. Early inhalational anthrax symptoms can be similar to those of much more common infections. However, a runny nose is a rare feature of anthrax. This means that a person who has a runny nose along with other common flu-like symptoms is by far more likely to have the common cold than anthrax. Most people with inhalational anthrax have high white blood cell counts and no increase in the number of lymphocytes, but people with infections such as flu usually have low white blood cell counts and an increase in the number of lymphocytes. Chest X-rays also are critical diagnostic tools, which show that all patients with inhalational anthrax have some abnormality, although for some patients, the abnormality is subtle. CT scans can confirm these abnormalities.
Q. Is there a quick test doctors can use to tell if a person has anthrax or an illness like the flu?
A. Some influenza detection tests give results fairly quickly. However, these tests are not perfect and are not appropriate for every patient. Rapid influenza tests can provide results within 24 hours; viral culture provides results in three to 10 days. However, as many as 30% of samples that test positive for influenza by viral culture may give a negative rapid test result. Some rapid test results may indicate influenza when a person is not infected with influenza.
Q. How many cases of flu and anthrax occur each year?
A. Each year, several tens of millions of people get "influenza-like illness" from many different infections during the fall and winter months. This happens every year and is expected. These illnesses are due to many different viruses and agents, including influenza viruses and common cold viruses. By contrast, few people ever get anthrax. Since October 2001, when the first cases of inhalational anthrax related to bioterrorism were diagnosed, only 10 cases have occurred in a few communities, and most of those cases occurred within particular groups of people (e.g., postal workers). Inhalational anthrax has not been diagnosed in most communities in the country.
Source: Centers for Disease Control and Prevention, Atlanta.
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