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Internal Medicine

Public·45 members

A 17-year-old whom she saw two days earlier for severe sore throat and malaise of five days duration. The patient was well until he developed the sore throat accompanied by low grade fever and “feeling tired and sick.” He doesn’t know anyone else who is sick. He is sexually active with a single partner and always uses condoms.

On exam, his temperature was 100.8°F; pulse 86, BP 112/78. He had periorbital edema and bilateral anterior and posterior cervical nodes that were more prominent posteriorly. His throat was red with small exudates. The spleen tip was palpable.

A rapid strep test performed in the family physician’s office was negative. The doctor thought the young man had mononucleosis and ordered a CBC and Monospot test (heterophile antibody). The WBC count was 12,000; there were 32% lymphocytes and 12% atypical lymphocytes and the platelet count was slightly low at 120,000.

The Monospot test was negative.

Which one of the following is most likely responsible for the young man’s illness?

  • Cytomegalovirus

  • HIV

  • Epstein-Barr virus

  • Toxoplasma

Mazen Kherallah

This patient has a classic mononucleosis syndrome. About 90% of mononucleosis like illnesses in adolescents and young adults are due to Epstein-Barr virus, and the peak age for EBV mononucleosis in the United States is 16 to 17 years of age. The Monospot test, a rapid agglutinin test for heterophile antibody, is highly specific but not highly sensitive.

The important point is: The false negative rates are highest during the beginning of clinical symptoms (25 percent are falsely negative in the first week; 5 to 10 percent in the second week, 5 percent in the third week).

Measurement of EBV-specific antibodies is usually not necessary since the majority of patients are heterophile positive. However, testing for EBV-specific antibodies can confirm the diagnosis if the heterophile test is negative and there is a need for a definitive diagnosis. IgM and IgG antibodies directed against viral capsid antigen (VCA) have high (>95%) sensitivity and specificity for the diagnosis of mononucleosis.

Ten percent of mononucleosis syndromes are due to other agents including HIV, CMV (sore throat less likely), toxoplasmosis (no sore throat), HHV-6 and HHV-7.

For strep pharyngitis there should be no splenomegaly and no severe fatigue.

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