Conjunctival swab in viral transport medium
Keep specimen at 4C
CONJUNCTIVAL SWABS should be taken by stroking the lower conjunctival sac of the eye 5-6 times with a rayon or Dacron tipped, plastic or metal shafted swab to obtain epithelial cells. To facilitate binding of the cellular material to the swab, the swab can be premoistened with sterile saline. Be certain to express the excess liquid from the swab before attempting to collect the specimen. After specimen collection, immediately place swab into tube of viral transport medium and send to the Clinical Virology Laboratory. If an extended delay in transport of specimens is anticipated, rapidly freeze the specimens to at least -60°C and transport to the laboratory on dry ice. Please consult the laboratory if necessary.
Swab specimens not received in viral transport medium or received in bacteriological transport medium are discouraged. DO NOT USE CALCIUM ALGINATE OR WOODEN SHAFT SWABS FOR COLLECTION OF SPECIMENS; ONLY USE DACRON OR RAYON TIPPED SWABS ON PLASTIC OR METAL SHAFTS.
Indirect immunofluorescence assay using primary monoclonal antibodies specific for measles antigens and secondary fluorescein-labeled monoclonal antibodies.
If positive, results are reported as measles (rubeola) virus antigen detected.
Negative or no measles (rubeola) virus antigen detected
Clinical Utility: Measles (rubeola) is an acute illness that begins with a prodrome of cough, coryza, conjunctivitis. Patients will have an ascending (stepwise) fever to 39.5C. Koplik's spots (enanthem) may be observed on the inside of the mouth opposite the molar teeth. Skin rash (exanthem) occurs within 2 to 4 days of the prodrome and lasts 6 to 7 days. Initially erythematous and maculopapular. Progresses to confluence over time. Illness is highly contagious from 1 to 2 days before symptoms (3 to 5 days before rash) to 4 days after rash develops. Complications include otitis media, bronchopneumonia, croup, diarrhea, acute encephalitis, and subacute sclerosing panencephalitis (SSPE). Risk factors include age (<2 yrs and adults), nutritional status (malnourished), and immunocompromise. Characteristic rash may not develop in immunocommpromised patients. Measles is still a common and often fatal disease in developing countries, with an estimated 30 to 40 million cases and 745,000 deaths in 2001. Measles accounts for 48% of the 1.6 million deaths due to vaccine-preventable diseases occurring annually among children. Localized epidemics still seen in developed countries like the United States. Most cases are imported or linked to importation. Diagnosis of measles virus infection can be made by detection of virus-specific IgM and IgG antibody in serum, growth of the virus in culture from respiratory, eye, urine and whole blood specimens, and by rapid and direct detection of viral antigens in respiratory and eye specimens. At CHOP, it is recommended that a nasopharyngeal aspirate and conjunctival swab be submitted for rapid antigen detection and that serum be collected and submitted for measles-specific IgM and IgG serologies.
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