Coccidioides precipitin

Definition

Coccidioides precipitin is a blood test that looks for antibodies to the fungus Coccidioides immitis, which causes the disease coccidioidomycosis.

Alternative Names

Coccidioidomycosis antibody test

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

This test specifically looks for the antibodies in the clear liquid portion of the blood, which is called the serum. An antibody defends the body against bacteria, viruses, fungus, or other foreign body. Certain cells tell the body to produce antibodies during an active infection.

How to prepare for the test

There is no special preparation for the test.

How the test will feel

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

The test is done to determine if you are infected with the fungus Coccidioides immitis, which causes the disease coccidioidomycosis.

Normal Values

No precipitins is normal. This means the blood test did not detect the antibody to Coccidiodies immitis.

What abnormal results mean

An abnormal (positive) result means the antibody to Coccidioides immitis has been detected.

In this case, another text is done to confirm infection. See: CSF coccidioides complement fixation. A titer less than 1:16 usually indicates no infection. However titers of 1:2 or 1:4 have been seen in people with active infection. A titer greater than 1:16 usually indicates active infection.

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

In the initial stage of an illness, few antibodies may be detected. Antibody production increases during the course of an infection. For this reason, such tests are often repeated several weeks after the first test is done.

References

Galgiani JN. Coccidioidomycosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 354.