What Is Infection?

Infection is defined as the process by which germs enter a susceptible site in the body and multiply, resulting in disease. Infection is a common problem in persons with cancer. Persons with cancer are at increased risk of infection as a result of:

  • The underlying disease, for example leukemia or lymphoma effects the body's normal defense against infection.
  • Side effects of treatment that interfere with the body's normal defense against infection.

The body's defense against infection includes:

Organs that are part of the immune system:

  • Skin and mucous membranes: The skin is the largest organ in the body and our first line of defense against infection. Any break in the skin is a potential site of infection.
  • For example: surgical site, or site where the IV catheter is inserted is susceptible to infection.
  • Thymus: Is a small glandular organ that is situated behind the top of the breastbone. It consists mainly of lymphatic tissue and serves as a storage place for T cells of the immune system
  • Spleen: Is located in the upper left side of the abdomen. It has many infection fighting functions such as filtering out foreign organisms, removing old or damaged cells, helping form some types of white blood cells. The spleen can be removed if damaged but this may lower your resistance to infection.
  • Lymph nodes: Are small collections of infection fighting cells that exist in chains along the course of the large blood vessels of the body. There are hundreds of lymph nodes throughout the body. These nodes filter lymph fluid, removing foreign substances such as bacteria that get trapped in their web-like structure. Then the infection fighting cells such as macrophages, antibodies, and T cells can destroy them.
  • Bone marrow: Located in the center of the bones of the body particularly in the bones of the spine, ribs, breast bone, pelvis and upper arms and legs. It is the principal site for production of blood cells.
  • Infection fighting cells of the immune system: Particularly the white blood cells (WBC). There are five main types of WBC's - lymphocytes (B and T cells), macrophages, basophils, eosinophils and neutrophils. When your white blood cell count is low there is an increased risk of infection.
  • The level of risk for infection depends on several factors:
  • How low the WBC count falls
  • How long the WBC count is low
  • Which type of WBC is low
  • One measure of risk for infection is the absolute neutrophil count (ANC). The ANC is calculated by multiplying the total WBC by the percent of neutrophils (also called segmented neutrophils, segs, polymorphoneucleated cells or PMNs, polys).

Total WBC x % neutrophils* = ANC

* Neutrophils may be reported as segs & bands (a band is slightly less mature form of a seg). In this case add the % of segs to the % of bands then multiply by the total number of white blood cells.

(% bands + % segs) x Total WBC = ANC

Risk of Infection based on Absolute Neutrophil Count (ANC)ANC greater than 1500No increased risk of infectionANC 1000-1500Slight increase in risk of infectionANC 500-1000Moderate increase in risk of infectionANC 100-500High risk of infectionANC less than 100Extremely high risk of infection

Since we know drugs and diseases that can decrease the normal body defenses against infection and the types of infection likely to occur in patients, most types of infection are potentially preventable and often treatable.

When your white blood cell count is low you may NOT have the usual signs and symptoms when developing an infection such as:

  • Redness
  • Swelling
  • Pus formation (at the site of an injury or incision)
  • Cough
  • Sputum
  • Nasal drainage (from a sinus or respiratory infection)

Therefore, it is extremely important to be alert to any change in how you feel and report and discuss what you are feeling with your doctor or nurse.

Things You Can Do To Manage Infection:

Learning needs: There is some important information that you need to learn about infection and how infection relates to the treatments you are receiving. This includes:

  • What to do to decrease your chances of infection.
  • Signs and symptoms of infection
  • When infection is most likely to occur
  • How to manage infection if it does occur.

Your health care provider will tell you when you are getting treatment that may cause your white blood cell count to be lowered. Additional information to ask is when the white blood counts will most likely be at its low point (nadir). This will give you a gauge as to when your body is less likely to be able to fight off infection.

Prevention of infection: Infection cannot be completely prevented. However, there are things you can do to decrease the risk of infection.

You are most susceptible to a bacterial infection about seven to 12 days after your chemotherapy infusion if your white blood cells are low. Most bacterial types of infection result from your body's inability to fight off normal bacteria present in your gastrointestinal tract or skin. Bacterial infection does not commonly result from being in a crowded place. However, types of viral infections such as colds and flu are common and are transmitted easily from other people.

To help to decrease your risk of infection:

  • In general, it is fine to go to public places. Avoid, if possible tightly crowded places during the height of the cold/flu season. Generally a mask will not offer much protection from infection, so it is better to avoid close contact with people coughing and sneezing.
  • Wash your hands often. For example:
  • After frequent handshaking
  • Before preparing food to eat
  • After touching raw meat like chicken or steak
  • Before eating
  • After using the restroom
  • After changing a baby's diaper
  • After coming into direct contact with someone who is very young or very old
  • After touching animals such as dogs or cats
  • Wash your hands the correct way to minimize risk of infection:
  • First, find a towel to dry your hands, a paper towel is better to use because you can throw it away (infection carrying germs can live on a wet cloth towel). Get the paper towel before you was your hands to keep from touching the knob or container with your clean hands. Put the towel under your arm until you are ready to use it.
  • Wet your hands with water. Warm water is best. Hot water can make your skin dry and itchy.
  • Put soap on your hands. Liquid soap is better because germs causing infection can live on bar soap. Bar soap is OK to use as long as you dry it on a soap bar.
  • Rub your hands together for 10 to 15 seconds or until all dirt is gone. To do a good job you need to wash in between your fingers, the back of your hands and your thumbs and under your fingernails. If you do not wash in all of these places, you may not remove all of the germs that can cause infection.
  • Rinse your hands with warm water. Make sure to rinse between your fingers and under rings. If you do not get all of the soap off, it could cause the skin to itch.
  • Dry your hands with a soft paper towel. Pat your hands dry - rubbing might damage your skin. If there is a blow dryer to dry your hands, push the button with your elbow.
  • Use the towel to turn off the water. (you don't want to get germs from the water faucet back on your clean fingers).
  • Keep your body clean by showering or bathing daily. If your skin becomes dry, use lotion or oil to soften your skin and prevent cracking.
  • Avoid injury, even small cuts or tears in the skin could be a susceptible site for infection.
  • Wear shoes or slippers to protect your feet from injury and/or infection.

Mouth care:

  • Keep your mouth clean by brushing your teeth twice daily. Use soft toothbrush and mouth rinses without alcohol. Do not use floss. Check with your healthcare professional before having any dental work done.
  • To help treat/prevent mouth sores, use a soft toothbrush, and rinse three times a day with 1/2 to 1 teaspoon of baking soda and/or 1/2 to 1 teaspoon of salt mixed with 8 ounces of water.
  • Avoid constipation and straining to have a bowel movement by using a medication that softens the stool. Drink 2 quarts of fluid a day. Check with your health care professional before using laxatives or enemas.

Food Safety:

  • Wash hands, utensils, and surfaces with hot soapy water before and after food preparation, especially after preparing meat, poultry, eggs or seafood.
  • Keep raw meat, poultry, eggs, and seafood away from ready-to-eat foods.
  • Do not place cooked food on an unwashed plate where raw meat, poultry, eggs, or seafood has been to reduce risk of infection.
  • Cook food well. Use a food thermometer to check the internal temperature. Cook meat until it is no longer pink and the juices are no longer clear. Cook eggs until they are firm. Bring sauces, soups, and gravies to a boil when reheating.
  • Do not eat raw food such as sushi, Caesar salad or milk shakes made with raw eggs, until you complete chemotherapy and your blood counts have returned to adequate levels.
  • Keep cold foods cold. Refrigerate or freeze foods that may spoil.
  • Refrigerate leftovers within 2 hours and make sure the refrigerator temperature is no higher than 40°F, and the freezer temperature is 0°F.
  • Never thaw food at room temperature; thaw food in the refrigerator.
  • Don't pack the refrigerator too full - cool air needs to be able to circulate to keep food cold and safe.
  • Thoroughly wash all fruits and vegetables.


  • Do not change cat litter or clean up waste (urine or feces) from animals (have someone else take this chore on during times of low WBC's when risk of infection is high).
  • Avoid contact with reptiles such as snakes, lizards, and turtles because of the risk of salmonellosis.
  • Avoid cleaning fish tanks because of possible exposure to Mycobacterium marinum.
  • Birds, especially if imported from other countries, should receive a clean bill of health from a veterinarian.


  • Routine flower and vegetable gardening is permissible using some infection precautions. Strictly avoid an environment where mulch, hay, topsoil, etc. is being "pitched" or spread. Inhalation of environmental spores, particularly from moist, dark areas (e.g. compost piles) may lead to infection and should be completely avoided. (Aspergillus spores that are abundant in these areas and if they are inhaled can cause serious disease in the immunosuppressed person).
  • Gloves should be worn for contact with dirt and soil and good hand washing after the gloves are removed is essential. If walking through areas where soil, dust and fungal spores may be found in the air cannot be avoided, wearing a mask is preferred.


  • People at highest risk for infection should not drink water directly from lakes or rivers. If necessary boil water for 1 full minute to avoid cryptosporidium and other waterborne organisms. Use of a submicron personal-use water filter may reduce the risk of infection. Be advised that swimming can cause accidental ingestion of water and may increase the possibility of acquiring cryptosporidium, even in public swimming pools. Avoid situations that would permit the inhalation of environmental spores, particularly from moist, dark areas (e.g. compost piles, rotting leaves etc.). Again these are areas where Aspergillus spores are abundant and if they are inhaled can cause serious disease in the Immunosuppressed person.
  • Hot tubs, saunas, and other communal baths are generally not recommended. Bacteria and other microorganisms thrive in warm water. However, if the immunosuppressed person is aware that the tub is adequately disinfected regularly as recommended then there is no contraindication their use.
  • Spelunking or cave exploration should not be done because of the infection risks associated with exposure to bat waste products.

Travel abroad: The risk of food and waterborne infections among immunosuppressed people at highest risk of infection is magnified during travel to developing countries.

  • Those who elect to travel should avoid foods and beverages that may be contaminated, particular raw fruits and vegetables, raw or undercooked seafood or meat, tap water, ice made with tap water, unpasteurized milk and dairy products, and items sold by street vendors.
  • Foods and beverages that are generally safe from infection include steaming-hot foods, fruits that are peeled by the traveler, bottled (especially carbonated) beverages, hot coffee and tea, beer, wine, and water brought to a rolling boil for 1 minute. Treatment of water with iodine or chlorine may not be as effective as boiling but can be used when boiling is not practical.
  • Prophylactic antimicrobial agents are not generally recommended for travelers, but your doctor may advise carrying certain medications with you. The effectiveness of these agents depends upon local antimicrobial-resistance patterns, which are seldom known.
  • Check with your physician for decisions based upon your level of risk for infection and the region and duration of travel.


  • Regular dusting, sweeping, windows, floor washing, bathrooms are okay to clean if you feel well. However, avoid cleaning or dusting areas where a lot of sediment can be aerosolized. Use common sense and avoid cleaning areas that have been untouched for years. (Aspergillus lives in dust, especially in old building). Wear gloves for washing heavily soiled areas and commodes.


  • In general, it is wise to avoid construction/renovation areas because of the possibility of aerosolized yeast or mold in the dust. If it is unavoidable an immunosuppressed person can reduce the risk of infection by wearing a particulate respirator (mask - NIOSH approved N95 respirator) and fitting it tightly to his face.


There are a few occasions when a mask (NIOSH approved N95 particulate respirator) is appropriate. If the immunosuppressed person must go into a construction/renovation area, or when exposed to heavy puffs of dust or debris. Additionally if required to have close contact with another (children, adults, etc.) who is ill with a respiratory infection (common cold, flu, childhood illness) a mask will reduce the risk of acquiring the infection.

Your Doctor or Health Care Provider May Prescribe or Suggest:

Your doctor or health care provider may prescribe or suggest:

The following medications may be given after each cycle of chemotherapy to prevent your white blood cells from falling too low and/or for too long.

  • Filgrastim (Neupogen®)
  • Peg - Filgrastim (Neulasta®)
  • Sargramostim (Leukine®)

The following are antimicrobial medications that may be prescribed to prevent specific infections that are common when the immune system is suppressed by chemotherapy and/or other medications.

  • Sulfamethoxazole - trimethoprim
  • Acycolovir®
  • Flucanozole®
  • Intraconazole®

Other antibiotics or antimicrobials are used to treat specific types of infection as needed.

When to Contact Your Doctor or Health Care Provider:

Call immediately if you have:

  • A temperature greater than or equal to 100.5°F (38°C)(Check with your health care provider, you may be instructed to call for temperature greater than or equal to 100°F).
  • Chills (rigors) or shakes .Sudden onset of a new unexplained pain.

Call within 24 hours if you experience the following:

  • Sore throat
  • Sores in your mouth
  • A white coating in your mouth, especially your tongue
  • Signs of a bladder infection
  • Burning with urination
  • Blood in your urine
  • Needing to urinate more frequently than normal

Note: We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website about infection and other medical conditions is meant to be helpful and educational, but is not a substitute for medical advice.

Related Side Effects

Infection has related side effects:

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