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Quick Facts

Occult Bacteremia


The Manual's Editorial Staff

Last full review/revision Dec 2019| Content last modified Dec 2019
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What is occult bacteremia?

Occult means hidden. Bacteremia is germs (bacteria) in the blood. So occult bacteremia is when bacteria are in the blood but haven't yet caused illness or symptoms other than a fever. Because the bacteria haven't yet caused sickness, the bacteremia is "hidden."

Occult bacteremia happens in babies and children under 3 years of age. After that age, bacteremia always causes symptoms.

  • With occult bacteremia, your baby or child has a fever but otherwise looks healthy

  • Doctors do blood tests to find occult bacteremia

  • Vaccines (shots that healthy children need to help protect them from many infections) also help prevent occult bacteremia

  • Doctors treat occult bacteremia with antibiotics

  • Without treatment, occult bacteremia may develop into a serious illness

What causes occult bacteremia?

Certain kinds of bacteria cause occult bacteremia. Children who receive all their vaccines are generally safe from occult bacteremia.

Children are more likely to get occult bacteremia if they:

What are the symptoms of occult bacteremia?

The only symptom is:

  • Fever higher than 102° F (38.9° C)

A baby or child who has other symptoms (such as cough, sore throat, or runny nose) has an actual infection, not occult bacteremia.

How can doctors tell if my child has occult bacteremia?

To find occult bacteremia, doctors do:

  • Blood tests

Doctors may do other tests to look for a bacterial or viral infection, such as:

  • Urine tests

  • Spinal tap (lumbar puncture) where a doctor uses a needle to get a sample of spinal fluid from around the spinal cord

  • Chest x-ray

  • Swab from the nose to look for a viral infection

The age of the child is important. Babies under the age of 3 months may need more tests and even to stay in the hospital during testing. Doctors can't always tell just by looking at very young babies whether they have occult bacteremia or a serious bacterial infection.

How do doctors treat occult bacteremia?

Doctors treat occult bacteremia with antibiotics. Your child may also be given medicine, such as acetaminophen, to reduce fever. Children under 3 months who are sent home with a fever should be seen again by the doctor in 24 to 48 hours.

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