Classified as a paramyxovirus, measles is a highly contagious viral infection. The disease is spread during the prodrome phase through direct contact with respiratory secretions in the form of droplets. Clinical signs and symptoms of the measles virus include high fever, cough, coryza, conjunctivitis, malaise, and Koplik spots on the buccal mucosa. An erythematous rash then develops behind the ears and over the forehead, spreading to the trunk.
Serology has become increasingly important as a tool for determining the immune status of the young adult population entering college or the military. In addition, the linkage between measles infection and premature delivery or spontaneous abortion supports screening pregnant mothers for susceptibility.
These tests determine susceptibility and immunity to measles virus. Since intensive immunization began in the United States in the 1970s, the incidence of measles infection has been reduced from approximately one half million cases annually (1960s) to fewer than 500 cases in recent years. Many individuals, however, may remain susceptible to measles virus because of vaccine failure or nonimmunization. A positive IgG coupled with a negative IgM result indicates previous exposure to measles virus and immunity to this viral infection. Positive IgM results, with or without positive IgG results, indicate a recent infection with measles virus.
Negative for measles IgG or IgM antibodies by ELISA: nonimmune
Positive for measles IgG antibody: immune; indicates a current or previous exposure or immunization to measles
Positive for measles IgM antibody (with or without positive IgG): indicates a recent infection with measles virus
Collect a 7-mL blood serum sample in a red-topped tube. Observe standard precautions. Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.
Follow-up testing may be required.
When testing for IgG antibody, seroconversion between acute and convalescent sera is considered strong evidence of a current or recent infection. The recommended interval between an acute and convalescent sample is 10–14 days.
Although the presence of IgM antibody suggests current or recent infection, low levels of IgM may occasionally persist for more than 12 months after infection or immunization.
IgM antibody response is detectable 2–3 weeks after appearance of the rash.
Pretest Patient Care
Assess patient’s test knowledge. Explain test purpose and procedure. Advise pregnant women that measles poses a high risk for serious complications and may be linked to premature delivery or spontaneous abortion.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal results; explain the need for possible follow-up testing and treatment. Advise women of childbearing age who test negative to be immunized before becoming pregnant. Inform patients who test positive that they are naturally immune to further measles infection.
Institute airborne precautions for patients suspected of measles or who pose a risk of transmission.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.