Signs and Symptoms

What Is a Sign and What Is a Symptom?

Although the words may sound interchangeable, doctors use the word "symptom" to mean something different from the word "sign." A symptom is anything a patient experiences or feels, such as a headache, dizziness, or the sensation of nausea (NAW-zee-uh). A sign, on the other hand, is something that can be noted by a doctor during a physical examination, such as elevated blood pressure, fever, or swollen elbow. Doctors, when they see a patient, typically ask about symptoms that the person might be experiencing and check the body for signs of disease. By carefully evaluating symptoms and signs of a patient's illness, by taking a thorough history, and, if necessary, by ordering laboratory tests, doctors can determine the nature of a patient's problem (that is, they can make a diagnosis).

Common Signs and Symptoms

Modern medicine uses all sorts of advanced laboratory testing and imaging techniques, such as X rays, computerized tomography ^* scans, and magnetic resonance imaging ^* . Most of the time, however, doctors make a correct diagnosis in the same basic way as physicians have for hundreds of years—by talking with patients about what hurts or what seems different about how they feel, and by examining patients to see whether an illness or problem can be seen, heard, felt, or even smelled. Certain bacterial infections, for example, have characteristic odors—such as the sweet smell caused by the bacteria ^* Pseudomonas aeruginosa. Just as with detective work, reaching the proper medical conclusion involves a lot of careful listening and observing.

People with infectious diseases, whether caused by viruses ^* , bacteria, or other agents, often have many of the same signs and symptoms. The following examples are some of the most common:

• Fever, which many patients recognize when they feel warm or hot, is described as any body temperature that exceeds about 100 degrees Fahrenheit. Fevers generally are described as falling into two categories: low grade, about 102 degrees or less, and high grade, about 103 degrees or more. A fever may spike, where it soars and then drops quickly, or cycle, where the person's temperature rises and falls at regular intervals. Chills and shivering sometimes appear with a fever, especially during a temperature spike.
• Coughs often accompany airway irritations—for example, the inflammation that comes with an airway infection, such as a cold, or with the postnasal drip of allergies. One purpose of the cough reflex is to protect the body by expelling irritants from the airway. When confronted with a cough in a physical exam, a
  

  By identifying the precise signs (objective information that a doctor gathers from physical examination and tests) and symptoms (the patient's subjective physical feelings and experiences), physicians can determine the nature of an illness or injury. In this case, the signs and symptoms indicate that this girl has a broken bone in her arm.
  physician tries to discover as much about it as possible, through talking with and examining the patient. Observing breathing patterns and listening through a stethoscope are important parts of such an exam.
• Congestion, otherwise known as a stuffy nose, may be caused by a viral infection, an allergy, or another problem that affects mucus ^* production in the airway or causes swelling and blockage of nasal and airway tissues.

• Nausea is the feeling that the patient is queasy or needs to vomit. People also may describe this sensation as an upset stomach. Some instances of nausea may be due to eating food contaminated with bacteria (such as Salmonella, sal-muh-NEH-luh, in chicken that was not cooked thoroughly), but other medical problems, such as a concussion ^* or kidney ^* failure, also can result in nausea. Vomiting or diarrhea (dye-uh-REE-uh) often accompany nausea.
• Sore throats (called pharyngitis, fair-un-JY-tis) are characterized as pain, discomfort, or a scratchy feeling, often when swallowing. The most common cause of sore throat is a viral infection, though there are many other causes.
• Muscle aches often accompany infections, but they also can stem from a variety of other causes, ranging from overuse of a muscle during work or exercise to autoimmune diseases ^* . Aches may occur over much of the body, or they may be confined to one area.
• Rashes are temporary changes in the skin's color and texture. They may erupt suddenly, and many are marked by inflammation. Some infectious diseases, such as chicken pox or Lyme disease, can be identified by their distinctive rashes. Rashes also can be caused by many noninfectious conditions, such as lupus ^* or allergies.
• Swollen lymph (LIMF) glands, or lymph nodes, may appear when the immune system ^* is fighting an infection. Lymph nodes contain cells that fight harmful microorganisms and are part of a system (the lymphatic system ^* ) that helps protect the body against infections. During certain infections these protective nodes, which are usually the size of peas, can swell and become tender. Lymph nodes may be swollen near the site of infection (for example, in the neck with strep, a bacterial infection of the throat) or more generally at different sites of the body (for example, in the groin, under the armpits, and in the neck with mononucleosis ^* and certain other viral illnesses).
• Jaundice (JON-dis) is a yellow hue to the skin, the whites of the eyes, and the mucous membranes ^* . A buildup of excess bilirubin ^* in the blood causes the color change. While jaundice in newborn infants often is harmless and easily resolved, in older children or adults, this symptom may signal a problem with the liver ^* , a blocked bile duct ^* , or an abnormal breakdown of red blood cells. Hepatitis B (heh-puh-TIE-tis), an infectious disease caused by a virus that inflames the liver, often results in jaundice.
• Malaise describes a general feeling of illness and exhaustion that can accompany various diseases. A patient with malaise will typically "just feel sick."
• Fatigue is a sensation of weariness or tiredness that may suggest too little sleep, too much physical activity, poor nutrition, stress, infection, or other medical or emotional problem. Patients who experience fatigue may or may not want to sleep.

• Weakness can be described as a loss of muscle strength. This symptom can be subjective, meaning that a patient feels the symptom but there is no measurable loss of strength, or it can be objective, meaning that a decrease in strength can be measured.
• Swelling is an enlargement of a part of the body, such as an area of skin or an organ. Swelling often stems from a buildup of fluid or tissue. It can occur in one specific area or throughout the body. Infections are just one possible cause of swelling.
• Irritability is a word often used to describe young infants who act extremely fussy and cannot be comforted as they usually would be. Irritability may signal any of a number of problems, including the start of an illness, even before other signs and symptoms appear.

What Is the Doctor's Role?

To arrive at an accurate diagnosis of an infectious illness, doctors take a "history." This means they ask patients about their symptoms, any medications they are taking, their past medical problems, and their family's medical problems. Then they examine patients and sometimes order laboratory and other diagnostic tests, as necessary. Putting together all this information, doctors then can consider the possibilities.

The questions posed to a patient in the course of the medical history are tailored to that person's particular symptoms. The doctor may ask for a description of the symptoms, such as how and when they occur. He or she may ask how long the symptoms last and what makes them better or worse. The doctor also may ask what sorts of illnesses the patient has had previously and whether anyone in the patient's family has similar problems or if certain diseases run in the family.

Once the doctor completes a medical history and a family history, the interview moves on to a complete physical examination. As the doctor examines different parts of the body, four basic techniques are used:

• Inspection is simply observing the affected body area or part.
• Palpation involves touching the area with the hands to check for size, texture, or tenderness.
• Auscultation describes the technique of using a stethoscope to listen to the sounds made by the heart, lungs, and intestines.
• Percussion is tapping the skin over organs with fingers or small instruments to produce different sounds. These sounds can reveal whether the organ is filled with fluid. Lungs, for example, should have a "hollow" sound, because they are filled with air, whereas the abdomen (the area below the ribs and above the hips that contains the stomach, intestines, and other organs) may have a duller, flatter sound because it contains some fluid.

To confirm a diagnosis or to gather additional clinical information, the doctor may also order laboratory tests. With test results in hand, the doctor combines this information with the knowledge gained from the

A sample of the discharge from an infection can be swabbed from the throat and placed in a culture medium, a jelly-like substance that aids bacterial growth. If the cause of a sore throat is bacterial, the bacteria will grow and multiply in the medium and then can be identified.

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