CLIA-Waived Immunologic Testing

Learning Objective: Examine CLIA-waived immunology testing.
      Immunology testing provides information about past or present infections with bacteria or viruses. It also detects certain types of cancers. Testing done in the immunology department is designed to demonstrate the reaction between an antigen and its specific antibody. Antibodies are formed when the body encounters a foreign agent.
      In the acute stage of a disease, the antibody level starts to rise and increases fourfold over the next several weeks. Paired testing of sera from the acute stage of illness and 2 weeks later that demonstrate a fourfold increase indicate the presence of the disease. During the later convalescent stage, the antibody level begins to decline for the next 3 to 6 months. Once the immune system recognizes an antigen, then antibodies are made. The antibody will remain in the blood at a low but detectable level for a lifetime. The amount of antibody can be measured with serologic testing called a titer.
      Most serologic/immunologic testing performed in the ambulatory care center is done using individual test kits (e.g., strep, influenza, mononucleosis, and human immunodeficiency virus [HIV] tests). The difference is the source of the specimen and what the test is looking for.
      The direct immunologic tests discussed in the previous section (strep test and influenza test) used a throat swab and nasal swab specimen. The test kits were detecting the antigen or pathogen causing the disease directly. In indirect immunologic tests, the specimen is the patient’s blood or serum. The blood or serum is tested to see whether the patient has produced the specific antibody to the pathogen in question. CLIA-waived immunology tests that can be performed by a medical assistant to detect antibodies to a pathogen include infectious mononucleosis, Helicobacter pylori, Lyme disease, and HIV tests.

Infectious Mononucleosis Testing
Learning Objective: Describe the process for infectious mononucleosis testing.
      Infectious mononucleosis, commonly called mono, is an acute infectious disease caused by the Epstein-Barr virus (EBV). EBV is one of the many herpes viruses. The virus is especially common in teenagers. It is found most frequently in people 10 to 25 years of age and is seen occasionally in adults over the age of 25. In the United States, about 95% of adults between 35 and 40 have already been infected.
      In children, the infection may pass unrecognized or result in a mild illness lasting only a few days. It is marked by sore throat, fever, swollen tonsils, and enlarged lymph nodes in the neck. In young people, some of the most common complications include the abrupt onset of fatigue, headaches, very swollen tonsils, enlarged lymph glands, and loss of appetite often associated with nausea. There may be a short or prolonged period (days or weeks) after the initial illness when the fatigue continues. Occasionally, complications occur, including the development of a swollen spleen or liver, referred to as hepatosplenomegaly.
      Testing for mononucleosis involves a complete blood count (CBC) and immunology tests, such as a CLIA-waived mononucleosis test. The CBC should reveal an increased number of lymphocytes that appear atypical on the blood smear. Due to the abnormally high number of mononuclear leukocytes in the blood, the illness was called mononucleosis. Most patients exposed to EBV produce a nonspecific heterophile antibody response to the virus. These heterophile antibodies in the patient’s blood react with the heterophile antigens supplied in the test kit, resulting in a positive color reaction in the testing area of the kit (Procedure 35.5).

35.6 Critical Thinking Application
Allyson Anderson is 15 years old. She came into the clinic today with signs and symptoms of infectious mononucleosis. Laura is going to do a fingerstick on Allyson and do a mono test. What are the typical signs and symptoms of mono in a teenager? What is the mono test checking for in Allyson’s blood?

Helicobacter pylori Testing
Learning Objective: Describe the process for Heliobacter pylori testing.
H. pylori is a spiral-shaped bacterium that can infect the stomach’s mucous layer or lining. H. pylori causes more than 90% of duodenal ulcers and more than 80% of stomach ulcers. Several methods can be used to diagnose H. pylori infection. Serologic tests that measure specific H. pylori antibodies can determine whether a person has been infected. CLIA-waived rapid immunoassay tests use whole blood applied to a well in a test cartridge. The blood migrates from the well through the testing area of the cartridge. The presence of a line in the test area of the cartridge indicates the presence of antibodies to the pathogen H. pylori.

Lyme Disease Testing
Learning Objective: Describe the process for Lyme disease testing.
      Lyme disease is the most common insect-borne infectious disease in North America, and it is a significant public health concern. The spirochete bacterium Borrelia burgdorferi is the most common causative agent in Lyme disease.
      The disease is contracted from an infected tick that bites a person. The bacteria are in the saliva of the tick. These ticks typically are found on deer, mice, dogs, horses, and birds. Infection occurs when the bacteria enter the tick bite. A characteristic bull’s-eye rash, known as erythema migrans (EM), develops at the bite site in 60% to 80% of patients. Lyme disease progresses in three stages. If the person is not treated, the disease progresses. The spirochete bacterium invades the skin, joints, central nervous system (CNS), heart, and other locations. Arthritic or CNS syndromes often accompany late-stage disease and may be the only clinical symptoms that indicate the infection.
      Lyme disease can be detected early with a CLIA-waived test, such as the Wampole PreVue B. burgdorferi test. This immunoassay tests for antibodies in whole blood. A sample of blood is applied to a test cartridge, a diluent is added, and the results are read in 20 minutes. The microbiology reference laboratory should verify any positive results.

HIV Testing
Learning Objective: Describe the process for HIV testing.
      HIV attacks and destroys the T-helper (CD4) lymphocytes. The T-helper lymphocytes play a critical role in protecting the body against infection. They work with the B lymphocytes to produce the specific antibodies that fight infections. As the HIV infection destroys more T-helper cells, the body becomes less able to fight off infections and more susceptible to opportunistic infections. If HIV is not treated with antiretroviral (ARV) medications, acquired immunodeficiency syndrome (AIDS) eventually develops. HIV infections become AIDS when life-threatening infections and cancers begin to appear.
      In 2013 the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) both advised preventive measures to control the disease. This requires early detection and early treatment of individuals infected with HIV. The sooner the virus is detected via immunology testing, the sooner treatment with ARV medications may begin.
       Two CLIA-waived HIV tests are readily available to detect the presence of HIV antibodies in blood and oral specimens. Patients at risk of HIV infection are now strongly encouraged to take a blood test available in POLs or outpatient clinics. Note that HIV is a bloodborne pathogen. The medical assistant should always follow the Bloodborne Pathogens Standard established by the Occupational Safety and Health Administration (OSHA) when collecting and testing all patient blood and body fluids. Remember, all patients are treated the same when it comes to the Bloodborne Pathogens Standards and Standard Precautions.