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What are infections and who is at risk?
Infection is the process by which germs (also called microbes
or microorganisms) enter the body, multiply, and cause illness. The
main types of germs are bacteria, viruses, protozoa (parasites), and
fungal organisms (also called fungi).
Infections in people who have cancer or are getting cancer
treatment can be more serious than those in other people. They can also
be harder to treat. If you have cancer, it is important to find
infections early and treat them quickly -- before they get worse and
spread.
The good news is that by learning more about them, you and
your family may be able to help prevent some infections. You can take
steps to avoid being exposed to dangerous germs, too. There are also
medicines you can take and things you can do to help prevent some
illnesses even after you have been exposed to them. And if you do get
an infection, it helps to know what to look for and what should be
done.
Cancer and the risk of infection
The cancer itself, as well as certain types of cancer
treatment, can increase your risk of getting a serious infection. Once
the cancer is gone and treatment is finished, the risk of infection
usually goes back to a more normal level. For most people, this
high-level risk for serious infection only lasts for a limited time.
Most people with cancer do not have a high risk of getting the
kinds of infections described here. Your risk of infection depends on
the type of cancer you have and the treatment you get. For example,
surgery does not weaken a person's resistance to infection nearly as
much as a bone marrow transplant. (For more information, see our
document, Bone Marrow and Peripheral Blood
Stem Cell Transplants.) Some chemotherapy drugs
are less likely than others to affect a person's resistance to
infection. It is important to weigh the risk of infection and other
side effects against the benefits of cancer treatment.
You may want to talk with your doctors before or during
chemotherapy or radiation therapy to see how this information applies
to you. Here are some questions you can ask your doctor or cancer care
team before and during cancer treatment:
- Will my cancer treatment make me more likely to get
infections?
- If I get an infection, how severe is it likely to be, and
how long might it last?
- Will you do anything special to prevent infections during
this time?
- What can I do to lower my risk of infection during this
time?
- How will I know if I have an infection?
- What should I do if I think I have an infection?
- If I get a fever, does that mean I have an infection?
- How will you decide how to treat my infection?
- What will you do if the treatment does not get rid of my
infection?
- What are the likely side effects of the proposed treatments
for infection?
How does a person's body normally resist
infections?
Your body has many ways to protect itself from infections. It
helps to understand the normal ways your body does this, and how cancer
and cancer treatment changes this process. This may help you better
understand why infections can develop so easily and be so serious in
people with cancer.
Skin and mucous membranes
Your skin is your body's largest organ and the most important
physical barrier against infections. It is your first line of defense
in protecting internal tissues from drying out (dehydration) and
harmful germs. When there is a break in the skin, germs (sometimes from
the air, but most often from the skin or things we touch) can enter the
body and cause infection.
The mucous membranes, which form the moist, pink lining layer
of the mouth, throat, nose, eyelids, urethra, vagina, and digestive
(gastrointestinal) system, also act as a barrier against infection.
These membranes normally help protect us from germs in the air we
breathe, our environment, and in our food and drink.
Cancer treatments (such as chemotherapy, radiation therapy, or
surgery) and invasive procedures (like putting in catheters, or getting
shots) can damage the skin or mucous membranes so that germs can get
inside the body.
The immune system and blood cells
If germs get through the skin and mucous membranes, the job of
protecting the body then shifts to the immune system and some of its
special blood cells. The immune system is a complex network of cells,
signals, and organs that work together to help kill germs that cause
infections. Many of these special blood cells travel in the blood until
they find germs to attack. Others spend part of their time in the blood
and the rest of their time in immune system organs.
How blood cells are made
Blood is made when cells in the bone marrow, called stem
cells, grow into different kinds of mature cells and are released into
the blood to do their work. There are 3 major kinds of blood cells.
- Red blood
cells (RBCs or erythrocytes) carry oxygen to cells
throughout the body.
- Platelets
(thrombocytes) help make clots to plug up holes that form in blood
vessels during injuries such as cuts, scrapes, or bruises.
- White blood
cells (WBCs or leukocytes) help fight germs that get into
the body
White blood cells fight infection
Unlike red cells and platelets, white blood cells are part of
the immune system. There are different types of white blood cells, and
they each have a key role in the body’s defense against
germs.
The type of white blood cell we have the most of is called the
neutrophil.
These cells form a very important defense against most types of
infections. Having a low neutrophil count is the biggest risk factor
for getting a serious infection.
Neutropenia
is the medical term used to describe a shortage of neutrophils. Ask
your doctor if your cancer treatment will cause neutropenia.
There are other important types of white blood cells:
- lymphocytes (especially the T-lymphocyte and B-lymphocyte)
- monocytes
- macrophages
Each type of white blood cell has a special role in fighting
infections.
Some treatments, most often those given during bone marrow
transplants, can cause a shortage of lymphocytes. Lymphocytes can fight
viruses. B and T lymphocytes have different jobs:
- B-lymphocytes make antibodies that recognize and kill some
germs. They also can mark germs to be destroyed.
- T-lymphocytes make signaling substances called cytokines that tell
other cells what to do.
Monocytes and macrophages have special jobs, too:
- They help lymphocytes recognize germs.
- Theycan surround and digest germs that have been coated by
antibodies (proteins made by B-lymphocytes).
- They help fight bacteria, fungal organisms, and parasites.
What risk factors make people with cancer
more likely to get infections?
Some types of cancer can damage the immune and blood systems
or change the way they work. For instance, lymphomas (Hodgkin and
non-Hodgkin) and certain types of leukemias start in immune system
cells. They change the immune system cells so that cells that once
protected the body begin to interfere with the normal way the immune
system works. Other types of cancer can affect the immune system, too.
But in most cases, it is the cancer treatment, not the cancer
itself that changes the immune system. The treatments can cause short-
or long-term damage. For example, long-term damage happens when immune
system organs such as the spleen are removed. A splenectomy (surgical
removal of the spleen) is sometimes done to remove cancer or learn how
much it has spread. Chemotherapy, radiation therapy, or a combination
of both can lead to short-term immune system damage.
Some people with cancer have a higher risk of infection
because of the changes in their body’s defense systems.
Cancer and cancer treatments can affect these systems in different
ways.
Immune suppression, leukopenia, and
neutropenia
Chemotherapy, radiation therapy, surgery, stem cell
transplant, bone marrow transplant, steroids, or the cancer itself can
suppress or weaken the immune system. This is sometimes called immunosuppression.
These treatments can lower the number of white blood cells (WBCs) and
other immune system cells, and can cause them to not work the way they
should. You may get an infection when there aren’t enough
WBCs, especially neutrophils, to destroy germs.
When looking at your risk of getting an infection doctors look
to see if you have a decrease in the number of neutrophils. This
condition is called neutropenia.
It is possible to have a normal total WBC count, but still be
neutropenic. But in most cases the WBC count is low when the neutrophil
count is low.
Absolute neutrophil count
You may hear your doctor or nurse talk about your absolute
neutrophil count or ANC. This is the number of neutrophils you have in
a certain amount of blood. Your health care team will use this number
to get an idea of how well your immune system is working while you are
getting treatment. You might want to keep track of your ANC, too, so
you will know when you are at a higher risk of getting an infection.
Figuring out
your ANC: The numbers for your ANC are taken from the
results of a blood test called the differential white blood cell (WBC)
count.
Normally, neutrophils make up 50% to 70% of WBCs. To find out
your ANC, multiply the percentage of neutrophils by the total number of
WBCs. Neutrophils are sometimes called "segs" or "polys," and young
neutrophils may be called "bands" on your lab report. And if there are
bands listed as a percentage of WBCs, those are added to the
neutrophils before multiplying.
You can figure out your ANC using this formula:
(% of neutrophils + % of
bands) X WBC count = ANC
100
So, for example, if a patient's WBC count is 1000 and the
percentage of neutrophils is 70%, and there are no bands, then the ANC
is:
(70 + 0) X 1000 = 700
100
Another example is if the patient’s WBC is 1300,
with 60% neutrophils and 5% bands. The bands are added with the
neutrophils (60 + 5), and the ANC is:
(60 + 5) X 1300 = 845
100
What the
absolute neutrophil count means: An ANC less than 1000
means that you have a low number of neutrophils and your immune system
is weak. This is called neutropenia and you may be called neutropenic.
The lower the ANC drops and the longer it lasts, the higher
your risk for getting a serious infection. If the ANC drops below 500
for a few days, you are at a high risk of getting an infection. If your
ANC is 100 or less for more than a week, your risk of serious infection
is extremely high.
As the ANC gets lower, the usual signs of infection, like pus,
pain, swelling, and redness may not happen. This is because these signs
are caused by neutrophils fighting off germs. So if you're neutropenic
you may not have enough neutrophils to cause signs of the body fighting
back, even though the germs are there. This makes it hard to know if
you have an infection. The good thing is that another WBC, called the
monocyte, can still cause fever (an increase in body temperature) in
the person who has neutropenia. In people with severe neutropenia, a
fever may be the only sign of an infection.
If your ANC is 1000 or lower and you have a fever of
100.5° F (37° C) or higher, your doctor will assume
that the fever is caused by an infection and will start treatment with
antibiotics right away. The longer neutropenia lasts and the lower the
neutrophil count, the higher your risk for a serious infection. During
this time infections must be found and treated as quickly as possible.
Tumor-related problems
Cancer cells can get into the bone marrow and replace the
normal cells there. The cancer cells compete with the normal bone
marrow cells for space and nutrients. If too many normal marrow cells
are destroyed or pushed out of the bone marrow, the remaining cells
will not be able to make enough white blood cells (WBCs) to fight
infection.
Cancer can also damage other parts of the immune system. A
tumor can grow through the skin or mucous membrane, breaking natural
barriers and allowing germs to get in. Tumors may also reduce blood
flow to the normal tissues by pressing on them or their blood supply.
Tumors in the lungs may block normal mucous drainage, which can lead to
infections. Tissues that have been damaged by cancer are more prone to
infections.
Cancer cells can also release chemicals that change normal
immune cells. This is a well-known effect of many cancers that start in
immune system cells, such as lymphomas, leukemias, and multiple
myeloma. It can happen with other cancers, too.
Poor nutrition
All cells need nutrients to grow and work. Changes in eating
habits, such as lower intake of vitamins, minerals, calories, and
protein can make your immune system weaker. Poor nutrition makes your
immune system less able to find and destroy germs. This means people
who are malnourished (do not take in enough calories and nutrients) are
more likely to develop infections. Cancer and cancer treatments can
also change the way your body uses the food you take in. This can
weaken your immune system, too.
People with cancer often have poor nutrition for many reasons:
- The cancer itself may make it hard to eat or digest food.
This is common in people with cancers of the digestive system, mouth,
or throat.
- Cancer treatments, like radiation therapy and chemotherapy,
may cause a loss of appetite and nausea.
- People with cancer often need extra calories and protein to
support their immune system cells and other tissues.
- Recovery from surgery increases the body's need for
nutrients.
- Cancer cells use up nutrients, leaving less to meet the
needs of normal, healthy tissues.
People with cancer often need help from nutritionists,
dietitians, and doctors to get enough calories and nutrients. Dietary
supplements, tube feedings, or even intravenous (IV, through a vein)
feedings may be useful in some cases.
Nutrition counseling and stress management may help increase
the immune function of people with cancer and may help prevent
infections. Nutrition counseling should include the importance of a
high intake of calories, protein, and vitamins. Other therapies such as
biofeedback, humor, music therapy, guided imagery, counseling, and
meditation may help manage stress and make it easier to eat.
Cancer treatment
Most of the cancer treatments used today can increase your
risk for infection.
Surgery
Any type of major surgery can suppress the immune system, but
the reason for this is not very clear. Researchers have seen decreases
in immune function within hours of surgery. Anesthesia (the drugs used
to make the patient sleep) may play a role. It may take from 10 days to
many months for an immune system to recover completely.
Surgery also breaks the skin and mucous membranes and exposes
internal tissues to germs. The wound caused by surgery (the incision)
is a common place for infection.
Surgery is often used to diagnose, stage, or treat people with
cancer. Things that raise the risk of infection after surgery include:
- how long the person was in the hospital
- the extent of the surgery
- how long the operation lasted
- the amount of bleeding during surgery
- nutritional status of the patient
- prior cancer treatment, such as chemotherapy or radiation
- other medical problems, such as diabetes, heart, or lung
problems
People with cancer may get antibiotics before having surgery
to help protect them from infection. Because surgery is often used to
treat people with cancer, it is important to be aware of the chance of
infection after surgery.
Chemotherapy
Chemotherapy or chemo is the most common cause of a weakened
immune system in people getting cancer treatment. The effects on the
immune system depend on many things, including:
- which chemo drugs are used
- chemo doses (how much is given at once)
- schedule (how often chemo is given)
- prior treatments for cancer
- age
- nutritional status
- type of cancer
- stage of the cancer
Some drugs have a greater effect on the bone marrow and immune
system than others. But chemo drugs may have different effects on how
well the body makes white blood cells, red blood cells, and platelets.
In most cases, white blood cells are the ones most affected by chemo
drugs. The effect chemo has on your blood cells doesn't last. Your
blood cell counts will go back to normal soon after treatment ends.
Radiation therapy
The effects of radiation therapy on the cells of the bone
marrow are much like the effects of chemotherapy. Both of these
treatments may cause neutropenia, which will increase the risk for
infections.
Many things affect the degree of neutropenia from radiation
therapy. These include:
- the total radiation dose
- the radiation schedule
- the part of the body being treated with radiation
- how much of the body is treated with radiation
Total body irradiation or TBI (where a person’s
entire body is treated with radiation) is the only type of radiation
likely to cause extremely low blood counts. Radiation is most often
given to just one area of the body, so the whole immune system is not
damaged by it. Still, depending on the dose and the part of the body
being treated with radiation, the skin or mucous membranes may be
damaged, making them less able to keep germs out.
Today, radiation treatments are given over many sessions
rather than in one large dose. This helps decrease the amount of skin
and tissue damage, immune suppression, and the risk of infections.
Biotherapy or immunotherapy
Biotherapy is also known as biologic therapy or immunotherapy.
It is given to make your immune system better able to recognize and
attack cancer cells. This can be done by helping your own immune system
to work harder or smarter; or by boosting your immune system by giving
you things like man-made immune system proteins. Immunotherapy is
sometimes used by itself to treat cancer, but it is most often used
with or after another type of treatment to add to its effects.
These treatments promote immune reactions against cancer
cells, but sometimes they can change the way the immune system normally
works. Because of this, people who get biologic therapies may be at
risk for immune suppression and neutropenia. Their WBC counts and
absolute neutrophil counts may drop, but will return to normal after
the treatment is stopped.
Hematopoietic stem cell transplant (bone
marrow transplant)
Hematopoietic
stem cell transplant (HSCT) is the term now used to
include both bone marrow transplant (BMT) and peripheral blood stem
cell transplant (PBSCT). These transplant therapies use very high doses
of chemo and/or total body irradiation (TBI) to try to kill all the
cancer cells in the body. In the process of killing the cancer cells,
the blood-forming stem cells of the patient's normal bone marrow are
also killed. Because of this, stem cells (either from the blood or bone
marrow) are removed from the patient before the high-dose chemo is
given. Or, if possible, they may be taken from a donor. Once the cancer
cells are killed, the saved or donated stem cells are given to the
patient to rebuild the immune system.
High-dose chemo is sometimes combined with TBI in transplant
treatments. This causes more severe neutropenia that lasts for a longer
period of time. These treatments, especially when used together, also
damage the skin and mucous membranes and make them less able to keep
germs out of the body.
For these reasons, very strict precautions are taken to try to
protect transplant patients from getting infections. This usually
includes
- keeping the transplant patient in a special area of the
hospital until WBC counts begin to reach normal (this often takes
weeks)
- limiting their exposure to outside people or other sources
of germs
- watching them closely for signs of infection, such as fever
Patients who get stem cells from other people may also need
medicine to prevent a serious problem called graft versus host disease.
These medicines suppress the immune system. For more information on
these procedures, see our document Bone Marrow and Peripheral Blood
Stem Cell Transplants.
Risk factors for infection can add up
As mentioned before, when your cancer treatment causes
neutropenia you have a higher risk of getting an infection. And when
your neutrophil count (ANC) is low, there are other factors that can
make your risk for infection even higher. For example, your chance of
getting a serious infection is much higher if your ANC is low and you:
- Have other serious illnesses
- Have cancer that is not controlled or is getting worse
- Have a very low neutrophil count (ANC is 100 or less) for a
week or more
- Are age 60 or older
- Have had a recent stem cell transplant
- Do not have normal liver and/or kidney function
- Have emphysema or other chronic obstructive pulmonary
(lung) disease
Some factors that may work in your favor
When your ANC is low, your risk for a serious infection is not
as high if you:
- Have none of the high-risk factors listed above
- Are expected to have neutropenia for less than a week
- Are able to do most of your daily activities for yourself
How does the doctor know what kind of
infection a person with cancer has?
People with cancer may get many different types of infections.
These infections differ in their risk factors, the symptoms they cause,
their prognosis (chance for curing the infection), and how they are
treated. When looking at the different types, 2 key aspects of the
infection are the part of the body affected and the type of germ
causing the infection.
Parts of the body most likely to get
infections
Your signs and symptoms (for example, where you have pain,
redness, or swelling) help your doctor know what tests are needed to
find the cause of the infection. The results of these tests (such as
x-rays, CT scans, or lab tests done on body fluids) help pinpoint where
the infection is.
The common sites of infection in people with cancer include
- the skin and mucous membranes
- the digestive system (esophagus, stomach, and intestines)
- the respiratory system (sinuses, throat, and lungs)
- the urinary system (bladder and kidneys)
- the nervous system (brain and spinal cord)
- the skin and tissue around a vascular access device (VAD).
The VAD is a tube or catheter placed in the vein that is used to draw
blood and give IV medicines or fluids.
The medical names for various types of infections sometimes
simply have, "-itis," added after the English, Latin, or Greek name of
a tissue or organ. Knowing some of these terms can help you understand
your medical conditions so that you can take a more active part in your
own treatment decisions. For example:
|
Body site affected by infection
|
Medical term |
| Deep layers of skin |
Cellulitis |
| Any area of mucous
membranes |
Mucositis |
| Mucous membranes of the
mouth |
Stomatitis |
| Mucous membranes of the
esophagus (tube that connects the throat and stomach) |
Esophagitis |
| Stomach and intestines |
Gastroenteritis |
| Mucous membranes of the
small intestine |
Enteritis |
| Mucous membranes of the
large intestine (colon) |
Colitis |
| Mucous membranes of the
small and large intestines |
Enterocolitis |
| Sinuses |
Sinusitis |
| Mucous membranes of the
throat (pharynx) |
Pharyngitis |
| Tubes leading into the
lungs (bronchi) |
Bronchitis |
| Lungs |
Pneumonitis or pneumonia |
| Urinary system in general |
Urinary tract infection
(UTI) |
| Urinary bladder |
Cystitis |
| Kidneys |
Pyelonephritis |
| Liver |
Hepatitis |
| Bone |
Osteomyelitis |
| Covering layer of the
brain and spinal cord |
Meningitis |
| Brain |
Encephalitis |
| Retina (part of the eye) |
Retinitis |
| Eye |
Conjunctivitis |
| Heart |
Myocarditis |
| Membranes covering the
heart |
Pericarditis |
Finding the
germs that cause infections in people with cancer
Infections are grouped by the type of germs that cause them.
Bacteria, viruses, protozoa (parasites), or fungi may cause infections
in people with cancer.
Most of the infections in people with cancer are caused by
germs that normally live on the skin, in the intestines, or in the
environment. These germs usually do not cause infections in people with
normal defenses and immune systems. But if the normal barriers and
immune system are weakened, these germs can begin to grow and cause
damage. These infections are often called opportunistic infections,
because the germs use the opportunity of a patient's weakened defenses
to cause illness.
Naming germs
Like all other living things, germs are given scientific names
that are made up of first names (genus) and last names (species). These
names tell biologists and health care workers which germs are related
and may be like each other. For example, the biological names Felis domesticus
(house cats) and Felis
leo (lions) tell biologists the animals are related. (Note
that scientific names are usually written in italics, except for
viruses.)
Likewise, Staphylococcus
epidermidis and Staphylococcus
aureus are related bacteria. But, like house cats and
lions, they differ in important details. Staphylococcus epidermidis
lives on our skin and rarely causes infections in healthy people. But
it can cause infections in people with cancer who have an IV
(intravenous) or vascular access device (VAD) and a low white blood
cell count. Staphylococcus
aureus can cause very serious infections in people with
weak or healthy immune systems. It is often resistant to many
antibiotics. This means these infections can be very hard to treat.
Although most germs have first and last names, those that are
very well known are often called by their first names only. Germs like
this include Pneumococcus, Candida, and Aspergillus. And like some
people, germs with long names are sometimes more commonly known by
their initials or nicknames. These include E. coli (Escherichia coli),
Staph epi (Staphylococcus
epidermidis), and CMV (cytomegalovirus).
Lab
tests to identify germs
Knowing the exact type of germ that is causing an infection is
very helpful in choosing the best treatment. Different drugs are used
to treat each of the main types of germs -- bacteria, viruses, fungi,
and parasites. And even among the main types of germs, different types
can have very different responses to different drugs. This means an
antibiotic that may kill one type of bacteria can have no affect on
another type of bacteria. Your health care team will do all they can to
find out exactly what germ is causing your infection. Here are some of
the tests they may use:
Gram stain
tests: Looking at samples from infected tissues under a
microscope can give clues about the type of germ involved. Bacteria,
fungi, and parasites are large enough to be seen under a regular
microscope, though they are much too small to see without one.
Sometimes, samples from the suspected site of infection can be taken
and treated with a series of stains (dyes). This test is called a Gram
stain. It changes the color of the germs to make them easier to see. It
takes only a few minutes and the result often helps doctors choose the
best antibiotics until other test results are available.
Tests for
viruses: Viruses are too small to be seen with most
microscopes. Instead, viruses are often identified by the types of
changes they cause in the cells they infect. Sometimes these changes
can be seen in cells from samples taken right from the patient. In
other cases, samples must be added to test cells grown in lab dishes.
If a virus is present, the test cells will undergo changes that lab
technologists can recognize.
Genetic tests: New
medical lab tests can quickly identify some germs by testing their DNA,
RNA, or other substances. These tests are often useful in choosing the
best treatment as fast as possible, before the infection causes serious
harm.
Culture: Samples
from the suspected site of infection are put in a nutrient broth or
gel, and kept warm until the germs grow. Germs most often need many
days to grow in the lab before they can be seen. After enough germs
have grown, some are removed and tested so they can be identified.
Sensitivity
tests: Once a germ has been cultured, an extra test
called a sensitivity test may be done. This test also takes time, but
it shows the best antibiotic to kill the germ involved. Because
infections in people with cancer may quickly get worse, treatment is
usually started before test results are back. Medicine to treat an
infection may then be changed after the lab tests have identified the
specific germ.
But how do doctors treat the infection
while they wait for lab test results?
Doctors know which germs tend to infect which organs of people
with cancer. So they can often make an educated guess at which germs
are most likely causing a patient's infection. Sometimes they are able
to use tests that can be done quickly, like the Gram stain, to narrow
down the type of germ. And many times patients who have had infections
before have the same germ come back later and cause another infection.
Educated guesses are very important because it can take many days to
get the results of the tests that show the exact type of germ causing
an infection.
Test samples or specimens
All of the tests listed above are done on samples or specimens
from the patient. Types of samples include blood, urine, spinal fluid,
wound drainage, and phlegm (sputum). If you have symptoms that point to
a certain organ, samples will be taken to check for germs in that area.
For example, sputum samples may be taken if you have a cough or
shortness of breath. Urine samples may be taken if you have blood in
your urine or feel pain while urinating. Sometimes, if a person has a
very low white blood cell count and is at high risk for developing
infections, samples will be taken before any symptoms start. If an
infection is found, treatment can then be given before symptoms start.
What
kinds of germs cause infections in people with cancer?
Bacteria
Bacteria are the smallest forms of life. Biologists believe
that bacteria are a separate life form -- they are different from
plants and animals. Bacteria cause most of the infections in people
with cancer. Some bacteria that commonly cause infections in people
with cancer include:
- Pseudomonas aeruginosa
- Klebsiella pneumonia
- Escherichia coli (E.
coli)
- Salmonella
- Clostridium difficile
(C. diff)
- Staphylococcus aureus
(Staph aureus)
- Staphylococcus
epidemidis
(Staph epi)
- Streptococcus viridans
- Pneumococcus
- Enterococcus
Viruses
Viruses are the smallest known germs. Unlike bacteria, they
are not really alive because they cannot grow on their own. Viruses can
only make new viruses when they are inside living cells, such as human
cells. Most viral infections in people with very low white blood cell
counts are caused by
- varicella zoster virus (VZV), the virus that causes
chickenpox and shingles
- herpes simplex virus (HSV), the virus that causes cold
sores and genital herpes
- cytomegalovirus (CMV)
Other viruses, such as respiratory and hepatitis viruses, may
cause problems, too.
Varicella
zoster virus
Varicella zoster virus (VZV) can cause serious infections in
people with cancer, especially children. Unlike many other infections,
a VZV infection never completely goes away. This means when healthy
people recover from chickenpox, some of the virus stays in their nerve
cells. If the person's immune system is weakened, even many years
later, the virus can become active again and cause a problem known as shingles. People
with shingles have groups of tiny, painful blisters on their skin. The
blisters form along the path of nerves.
These skin blisters are painful, but the most serious part of
VZV infection in people with a weak immune system is that the virus may
spread to other organs. This can lead to pneumonia (lung infection) or
encephalitis (infection of the brain). The risk of serious tissue
damage from VZV is high in people with low white blood cell counts and
immune systems that have been weakened by cancer. Unlike chickenpox
infections in healthy people, VZV infections in people with cancer can
be deadly.
Herpes simplex virus
Herpes simplex virus (HSV) is from the same family of viruses
as varicella zoster. Like varicella zoster, HSV causes mild infections
in people with healthy immune systems, but it also stays in their nerve
cells. It can be reactivated if the person has immune system changes
years later. And like varicella zoster, HSV can also cause pneumonia
and encephalitis.
Cytomegalovirus
Cytomegalovirus (CMV) infection in healthy people is usually
not serious. But in people with weak immune systems, CMV can cause
things like serious pneumonia, enteritis (intestinal infection),
hepatitis (liver infection), and retinitis, a serious eye infection
that can lead to permanent blindness if not treated.
Respiratory viruses
Respiratory viruses are those like influenza (the flu),
respiratory syncytial virus (RSV), and other seasonal viruses. They can
cause illness in people with normal immune systems, but these illnesses
may become severe in those with weak immunity. Respiratory viruses can
affect the nose, throat, sinuses, breathing passages, and lungs.
Pneumonia, which affects the lungs, is the most serious problem that
can be caused by respiratory viruses. Pneumonia is more likely when one
of these viruses infects a person whose immune system isn’t
working well.
The best prevention for influenza is to get the flu shot every
fall and have other household members vaccinated, too. Wash your hands
often when these viral infections are going around. This will also help
decrease the chances of infection. People with low white blood cell
counts should try to stay away from crowds and people with these kinds
of infections. We will talk about this more in the section "What can people
with cancer do to prevent infections?"
Protozoa
Protozoa are one-celled creatures that are thought to be the
smallest and simplest form of animals. Some protozoa can infect people
who have healthy immune systems. But these infections are more common
in less-developed countries than in the United States. In the US, most
protozoal infections happen in people with immune systems that have
been weakened by organ transplants, cancer, AIDS, or other diseases and
can be life-threatening. Common protozoa that can infect people with
cancer include
- Toxoplasma gondii
- Cryptosporidium
Toxoplasma gondii
Toxoplasma
gondii is found in soil, cat waste, and undercooked meats.
It can cause fever and lymph node swelling or no symptoms at all in
adults with normal immune systems. It becomes inactive, but when the
immune system is weak the infection may reactivate and damage the brain
or heart.
Cryptosporidium
Cryptosporidium
is a common cause of enteritis (intestinal infection) in people with
weak immune systems. It is spread by infected people and animals, often
through drinking water contaminated with stool. It can cause severe
diarrhea, malnutrition, weight loss, imbalances in blood chemistry, and
dehydration.
Fungi
In humans, fungi can live in balance with other germs that
normally live on or in the body without causing symptoms or damage. But
a fungal infection can happen when there are changes in this balanced
environment. Things that can change the normal balance include:
- damage to the skin or mucous membranes
- low white blood cell counts
- a weak immune system
- lower numbers of bacteria than normally found on the body's
surfaces (which often happens with antibiotic treatment)
Fungal infections can be serious and even deadly. Fungi that
commonly infect people with cancer include:
- Pneumocystis
jirovecii (formerly known as P. carinii)
- Candida
(yeast)
- Aspergillus
- Cryptococcus
- Histoplasma
- Coccidioides
Pneumocystis jirovecii
Pneumocystis
jirovecii is usually classified as a protozoan, even
though its DNA, RNA, and other parts look more like a fungus. It causes
pneumonia and rarely spreads to other organs.
Candida
This is the most common cause of fungal infection. Candida can live in
a healthy person without causing any problems. Sometimes it may cause a
mild skin rash or vaginal discharge (called a yeast infection). But a
person with a weak immune system is at risk for a much more serious
infection called thrush. It can affect the mouth and esophagus
(swallowing tube) and may even spread to other organs.
Aspergillus
Aspergillus
is a fungus that is often found in the air and in our environment. It
is rarely a problem in healthy people, but it can cause serious
infections of the sinuses, lungs, kidneys, brain, and heart valves in
people with cancer, especially those with very low white blood cell
counts or those getting cancer treatments that suppress the immune
system. This type of infection is often hard to diagnose and aggressive
treatment is needed as soon as it is suspected.
Cryptococcus
Cryptococcus
is found in the soil and in bird droppings, especially pigeon waste. It
is thought to be spread by breathing in the germ when it has dried out
and gets stirred up into the air. In people with healthy immune systems
it may cause a lung infection that goes away without symptoms. But the
fungus can remain inactive in the lungs for years. And if the person's
immune system later becomes weak, Cryptococcus
can begin to grow and spread to other parts of the body. One of the
most serious outcomes of this infection is meningitis, an infection of
the membranes that cover the brain and spinal cord.
Histoplasma
Histoplasma
is another fungus that often infects the lungs of healthy people
without causing any symptoms or tissue damage. People become infected
through contact with soil that contains bird or bat waste. Like Cryptococcus, the
fungus may remain inactive for many years in the lungs of healthy
people. But it can become active if their immune system is weakened. In
people with cancer, Histoplasma
may cause a serious infection and may spread to the lymph system,
liver, and spleen.
Coccidioides
Coccidioides
causes a fungal disease called coccidioidomycosis or Valley Fever. The
fungus lives in the soil in the southwestern United States, parts of
Mexico, and South America. People breathe in this fungus when dust
containing it is stirred up. Most people with healthy immune systems do
not know they have the disease and it goes away on its own. But Coccidioides can
cause serious illness in people with weak immune systems. It can spread
outside the lungs to the skin, nerves, brain, bones, and joints.
What can
people with cancer do to prevent infections?
Infection is one of the most common life-threatening
complications of cancer. If you are being treated for cancer, it is
very important that you take action to reduce your risk of infection.
Immunizations and live virus vaccines
People with weakened immune systems should not get vaccines
that contain live virus. There have been fatal infections caused by
polio, measles, and smallpox because live virus vaccines were given to
patients with weak immune function. Still, certain preventive
immunizations can be very helpful. It's important to know which
vaccines are safe for people with weak immune systems. We will talk
about the most common ones here. Be sure to talk to your doctor before
you get any vaccine. You should also tell your doctor before anyone you
spend a lot of time with gets a vaccine.
Flu shots
The flu shot can reduce the risk of pneumonia (lung
infection). It may be given at least 2 weeks before chemo or between
chemo cycles. It can be given 6 months after a bone marrow or stem cell
transplant, and every year after that. Flu-mist®,
the nasal
mist version of the flu vaccine, contains live virus. It should not be
used for people with cancer or their household members.
For more information on this, see our document Should Cancer Patients Get a Flu
Shot?
Polio and smallpox
Children who have weak immune systems, as well as their
siblings and others who live with them, should get inactivated virus
vaccines. They should not get the oral poliovirus vaccine. This is
because the oral poliovirus vaccine contains a live virus. People who
get this live virus vaccine can transmit the poliovirus to people with
weak immune systems.
Live virus vaccines can often be given at least 3 months after
all immune-suppressing treatment has stopped. But this time varies and
you should talk to your doctor before you or anyone you spend a lot of
time with gets a live virus vaccine.
For more information on smallpox vaccination, see our document
Smallpox Vaccine and Cancer.
Measles-mumps-rubella
People who have very weak immune systems should not get the
measles-mumps-rubella (MMR) vaccine because it contains live virus. But
unlike polio and Flu-mist®, it is safe
for other household
members to get it.
If the patient being treated for cancer is exposed to someone
with measles, it is important to let the doctor know right away.
Sometimes, measles immune globulin (a blood product that contains
antibodies to the measles virus) can be given to help fight measles
before it starts.
Varicella (chickenpox)
This is another live virus vaccine. So people with blood tests
that do not show immunity to the varicella zoster virus (VZV) are not
given this vaccine while their immune systems are weak. It is OK for
household members of the person with weakened immunity to get the
varicella vaccine.
A person with weak immunity who has been exposed to chickenpox
should call their doctor as soon as possible. They may need to get VZV
immune globulin (a blood product that contains antibodies to the VZV
virus) right away -- it must be given within 72 hours of exposure.
Cancer treatment may be stopped and restarted after the end of the VZV
incubation period, which is usually about 21 days. When a person with
cancer has signs of VZV infection, the doctor may hold off on cancer
treatment that causes immune suppression until scabs have formed.
Varicella zoster (shingles)
Zostavax® is a newer live virus
vaccine that is given
to prevent varicella zoster virus infection in adults age 60 and older.
At this time it is not approved for use in people with weakened immune
systems. Talk to your doctor before you or anyone in your household
gets this vaccine.
See the section, "Varicella
zoster virus" under "What kinds
of germs cause infections in people with cancer?" for more
information about shingles, a serious condition caused by this virus.
Precautions you can take
Always know when your absolute neutrophil count (ANC) is low.
Ask your doctor or nurse. Here are some things you can do that may help
to prevent illness during that time:
- Be aware of the signs and symptoms of infection. Report any
you have to your doctor or nurse right away.
- After bathing, look for redness, swelling, and soreness
where any tubes or catheters enter your body.
- Get your flu shot every fall. Encourage other members of
your household to get it, too. (Remember: Do NOT get the nasal mist flu
vaccine. Remind other people who live in the same house as you not to
get it either. Nasal flu mist should not be used in people with poor
immune function, or the members of their households.)
Here are some things you can do to avoid being exposed to
infection while your ANC is low:
- Avoid large crowds of people.
- Stay away from anyone with a fever, flu, or other
infection.
- Keep yourself clean by bathing each day. Be sure to wash
your feet, groin, armpits, and other moist, sweaty areas.
- Wash your hands with warm water and soap after using the
bathroom, blowing your nose, coughing, or sneezing.
- Wear gloves for gardening and wash up afterward.
- Wash your hands before eating and before touching your face
or mucous membranes (eyes, nose, mouth, etc).
- Do not get a manicure or, pedicure. Do not use false nails
or nail tips.
- Wear shoes all the time -- in the hospital, outdoors, and
at home-- this helps you avoid injury and keeps you from getting extra
germs on your skin.
- Use an electric shaver instead of a razor. Do not share
shavers.
- If you cut or scrape your skin, clean the area right away
with soap and warm water. Cover the area with a clean bandage to
protect it. If the bandage gets wet or dirty, clean the area and put on
a new bandage. Tell your doctor if you notice redness, swelling, pain,
or tenderness.
- Keep your mouth clean by brushing your teeth twice each
day. Ask your doctor or nurse if it is OK to gently floss your teeth.
Tell your doctor or nurse if your gums bleed. Your doctor or nurse may
give you a special mouthwash to help clean your mouth. Do not use
alcohol-based mouthwash.
- Prevent constipation and straining to have a bowel movement
by drinking 2 quarts of fluid each day. Exercising each day can help,
too. Let your doctor or nurse know if you are having bowel problems. If
needed, your doctor may give you medicine that softens your stool. Do
not put anything in your rectum, including thermometers and
suppositories.
- Keep your groin area and anal area clean, using soft moist
cloths (such as disposable baby wipes).
- Women should not use tampons, vaginal suppositories, or
douche.
- Use water-based lubricants during sex to avoid injury or
abrasion of the skin and mucous membranes. Use latex or plastic condoms
to reduce the risk of sexually transmitted infections.
- Do not keep fresh flowers or live plants in your room.
- Do not clean up droppings from your pets. Do not clean bird
cages or fish tanks. Let someone else do this for you.
- Place cat litter boxes away from kitchens and food areas.
Litter boxes should be cleaned every day by someone else.
- Do not touch soil that may contain feces (stool) of animals
or people.
- Do not wade, play, or swim in ponds, lakes, or rivers.
- Do not change diapers, but if you do, wash your hands very
well afterward.
- Stay away from all standing water, for example, in vases,
denture cups, and soap dishes.
- Use hot water to clean your dishes.
- Do not share bath towels or drinking glasses with others,
including family members.
- Stay away from chicken coops, caves, and any place where
dust from the ground is being blown into the air, such as construction
sites.
- Talk with your doctor or nurse if you are planning any
travel during this time.
Food safety
Food safety is very important when your ANC is low. Infections
can be picked up from food and drinks. A low microbial diet (or neutropenic diet)
may be suggested if your ANC is low. This type of diet and these
actions help you reduce infection risk from foods:
- Do not eat or drink any raw milk or milk products, or any
milk or milk product that has not been pasteurized, including cheese
and yogurt made from unpasteurized milk
- Do not eat raw or undercooked meat, fish, chicken, eggs, or
tofu
- Do not eat cold, smoked fish
- Do not eat hot dogs, deli meats, or processed meats (unless
they have been cooked just before eating)
- Do not eat any food that contains mold (for example, blue
cheese, including that in salad dressings)
- Do not eat any uncooked vegetables and fruits
- Do not eat uncooked grain products
- Do not eat unwashed salad greens
- Do not eat vegetable sprouts (alfalfa, bean, and others)
- Do not drink fruit or vegetable juices that have not been
pasteurized
- Do not eat raw honey (honey that has not been pasteurized)
- Do not eat raw nuts or nuts roasted in their shells
- Do not drink beer that has not been pasteurized (this is
most often home brewed and some microbrewery beers)
- Do not eat brewer’s yeast
- Do not eat any outdated food
- Do not eat any cooked food that has been left at room
temperature for 2 hours or more
- Do not eat any food that has been handled or prepared with
unwashed hands
- Talk with your doctor about any dietary concerns you may
have, or ask to talk with a registered dietitian
Use of medicines to prevent infections
Sometimes, antibiotics (which can be anti-bacterial,
anti-viral, and/or anti-fungal drugs) are given when a
person’s ANC is very low -- even though there is no sign of
an infection. You may hear this called prophylactic antibiotic
use. The drugs are given to help keep you from getting a bacterial,
viral, or fungal infection. This is only done when there is a very high
risk of getting one of these infections, for example, if you are
expected to have severe neutropenia for a week or longer, or you are on
other medicines that can make your immune system weak, such as a long
course of steroids. The prophylactic antibiotics are then stopped when
your ANC begins to improve. Using these drugs in this way does not
prevent all infections, so it is still important to use the same
precautions as people who are not taking prophylactic antibiotics.
Use of growth factors
Growth factors are also known as colony-stimulating factors
(CSFs). They are proteins your body makes to help your blood cells
grow. CSFs are most often used after chemo to keep your white blood
cell (WBC) count up and help prevent infection. You may be given a CSF
to help your WBCs grow and keep your absolute neutrophil count (ANC)
from getting too low. Or, you may get it when your ANC is low to help
build it back up. Your doctor also may give you a CSF if your ANC is
low and you have a serious infection such as pneumonia, a fungal
infection, or any other infection that is getting worse even though you
are getting treatment.
CSF drugs used today include filgrastim (Neupogen®)
and pegfilgrastim (Neulasta®), which
affect the neutrophils.
Sargramostim (Leukine®) is a CSF that
affects neutrophils,
monocytes, and macrophages. All of these medicines shorten the length
of time a person is neutropenic and make the shortage of WBCs and the
neutropenia (a shortage of neutrophils) less severe. Growth factors do
have some side effects, but they can reduce the risk of infection in
the patients who need them. Call us to get more information on each of
these drugs.
What signs of infection should people with
cancer watch for?
It is important to watch for early signs of infection and tell
your health care team about them right away. Then treatment can be
started as early as possible. This is most important for people who
have a low white blood cell count. Signs and symptoms of an infection
include:
- body temperature, taken by mouth, of more than
100.5°F
- sore throat
- cough or shortness of breath
- nasal congestion
- burning or pain with urination
- shaking chills
- redness, swelling, or warmth at the site of an
injury, surgical wound, or vascular access device (VAD)
Fever is especially important because it is often the first
sign of an infection in people with cancer. Patients are often told to
call their doctor or nurse if they have a fever greater than
100.5°F or
if they have other signs and symptoms of infection. Ask your doctor
what you should do if this happens. Be sure you know how to reach your
health care team after office hours and on weekends.
It is important for people with cancer and their families and
friends to know these things:
- the patient's risk for infection
- how long the white blood cell count or absolute
neutrophil count is likely be low after treatment
- the importance of taking the patient's temperature,
how to take it the right way, and how often to check it
- when to report a fever or other signs and symptoms
of infection to the doctor or nurse
- the importance of basic hand washing and hygiene
practices for the patient and the people they come in contact with
- the importance of cleaning around the anus after
each bowel movement and urination
- how to take good care of the mouth and check for
sores and fungal infections
- good care of vascular access devices (VADs)
- where to look for signs of infection (skin, mouth,
and VAD sites)
- the importance of good nutrition, a balanced diet,
and drinking plenty of fluids
- the importance of sleep and exercise and how to
save energy
- the need to take medicines as prescribed and be
sure the doctor knows about all medicines you are taking (prescription,
over-the-counter, vitamins, herbs, and supplements); it helps to review
and update this list at each doctor visit
- ways to prevent dryness of the skin and mucous
membranes (such as using lotion or using a vaporizer for humidity)
- the need to talk with your health care team or
doctor before getting any immunizations (vaccinations) and before close
contact with children or adults who have recently been immunized
(vaccinated)
How is infection treated in people with
cancer?
Fever and other signs and symptoms of infection in a person
with a weak immune system are looked at as medical emergencies.
Antibiotics need to be started right away. After a complete physical
exam, lab tests will be done to try to find out exactly which germ is
causing the infection and where the infection is. Antibiotics (which
can be anti-bacterial, anti-viral, anti-fungal, or anti-protozoal
medicines) are started before all the lab results are back. After the
specific germ is identified, the antibiotic may be continued if the
germ is sensitive to it, or a different medicine may be given.
Where treatment is given
In the past, patients were almost always put in the hospital
to treat these infections, and many still are. But some patients can
take their antibiotics in pill or liquid form. And some patients who
need intravenous (IV) antibiotics may be able to get them in clinics,
doctor's offices, or at home. Still, home care is only possible with
infections that are not likely to become more serious. The patient must
have a responsible adult at home with them at all times, and be able to
handle treatment at home. The patient must also be close enough to the
hospital or clinic to get there quickly and must have a telephone. The
doctor or cancer care team must be able to see the patient daily for
the first few days and do needed tests. If all goes well, they still
will need to stay in close contact during treatment. Otherwise, the
patient may need to be put in the hospital.
What treatment may be like
At first, the patient is watched closely and lab results are
checked often. The white blood cell (WBC) count and absolute neutrophil
count (ANC) are checked daily. Antibiotics may be changed when the
final culture results come in (this is the test that tells which germ
is causing the infection). If the infection does not respond to
treatment or keeps getting worse, an infectious disease specialist may
be called in. These doctors specialize in treating infections and may
recommend extra testing and different treatments, depending on the
situation. In some cases, CSFs (colony-stimulating factors) may be
given to speed up recovery of the WBCs so the body can better fight the
infection.
Each type of infection (bacterial, viral, protozoal, and
fungal) is treated with different drugs. We will name some of the mores
common drugs used in these next sections. But if you have any questions
about drugs you may be given or why you're taking them, please talk to
your doctor or nurse.
Bacterial infections
When treating bacterial infections, antibiotics are started
after samples for lab tests have been taken, but before these test
results have identified the germ. (See the section "Lab tests to
identify germs.") Doctors think about the site of infection
and the
germ most likely causing it when deciding which antibiotics to use at
this point. Most often, antibiotics that will treat many different
bacteria are chosen. These are called broad-spectrum antibiotics.
Sometimes 2 or 3 antibiotics are used at the same time. But overuse of
antibiotics is avoided because this can cause some bacteria to become
resistant to these drugs. For example, some strains of Staphylococcus
have become resistant to most antibiotics that can be given by mouth,
and even intravenous (IV) vancomycin, which was once used to treat
them. Such germs are called drug
resistant because they no longer
respond to the antibiotics that killed them in the past. Germs change
and adapt all the time. The good thing is that there are a handful of
new drugs, such as quinupristin/dalfopristin (Synercid®),
linezolid (Zyvox®), and daptomycin
(Cubicin®) that can
still work against some of these hard-to-kill germs. To avoid spreading
drug-resistant bacteria to other patients, health care workers often
wear disposable gowns and gloves when caring for people known to have
these infections.
Viral infections
While anti-bacterial antibiotics have been available for more
than 60 years, anti-viral drugs are much newer. Herpes simplex virus
and varicella zoster are most often treated with anti-viral agents like
acyclovir, valacyclovir, or famciclovir. Ganciclovir, foscarnet
(Foscavir®), cidofovir (Vistide®),
or valganciclovir
are used to treat cytomegalovirus (CMV). If influenza is the problem,
it may be treated with zanamivir (Relenza®)
or oseltamivir
(Tamiflu®). Other viruses may be treated
with other anti-viral
drugs.
Protozoal infections
Protozoa seldom cause problems for healthy people, but they
are hard to treat in people with weak immune systems. The usual
treatment for people with Pneumocystis
jirovecii infection is
trimethoprim-sulfamethoxazole (Bactrim®).
If this drug causes
side effects, dapsone, atovaquone (Mepron®),
or pentamidine
(Nebupent®) may be used. Toxoplasma
is often treated with
pyrimethamine (Daraprim®) plus
sulfadiazine or clindamycin (for
people who are allergic to sulfadiazine). There is no one treatment for
Cryptosporidium
infection, which causes severe diarrhea. Treatment is
aimed at building up the immune system and keeping the person from
losing too much fluid and nutrients.
Fungal infections
Oral anti-fungal drugs like nystatin and clotrimazole are used
for people with Candida
infections in the mouth and throat. Depending
on the medicine, the patient swishes and swallows a solution or lets a
wafer dissolve in their mouth. For Candida
in the esophagus,
fluconazole (Diflucan®) or another
anti-fungal drug is used.
For more serious Candida
infections (such as infections in the blood),
medicines like amphotericin B or one of its newer formulas may be given
IV (intravenously). Amphotericin is most often used to treat
Aspergillus
infection. Cryptococcus
and Histoplasma
infections are
usually treated with anti-fungal drugs like amphotericin, flucytosine,
ketoconazole, or fluconazole.
Where can I get more information on
infections?
From your American Cancer Society
- Understanding Your Lab Test Results
National organizations and Web sites*
In addition to the American Cancer Society, other sources of
patient information and support include:
Centers for Disease Control and Prevention (CDC)
Toll-free number: 1-800-232-4636 (1-800-CDC-INFO)
Web site: www.cdc.gov
National Cancer Institute
Toll-free number: 1-800-422-6237 (1-800-4-CANCER)
Web site: www.cancer.gov
* Inclusion on
this list does not imply endorsement by the
American Cancer Society.
No matter who you are, we can help. Contact us anytime, day or
night, for cancer-related information and support. Call us at
1-800-ACS-2345
(1-800-227-2345)
or visit www.cancer.org.
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Last Medical Review: 09/08/2008
Last Revised: 09/08/2008
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