Monospot (EBV heterophile antibody) test for glandular fever

Glandular fever, medically called infectious mononucleosis, is usually caused by the Epstein-Barr virus (EBV). During the illness the immune system makes unusual antibodies called heterophile antibodies, which react with proteins from other species such as animal red cells. The Monospot test looks for these antibodies. Lab Tests Online UK describes it as a rapid screening test, easy to perform, that remains the point-of-care diagnostic test of choice in many clinical settings.

The NHS describes glandular fever as a viral infection that mostly affects teenagers and young adults, most common between 15 and 24, with symptoms that include a high temperature, swollen glands, sore throat, rash, headache and tiredness.

A doctor requests the test when someone has fever, sore throat, swollen glands and fatigue, sometimes with an enlarged spleen or liver. The NHS says a GP may order a blood test to confirm glandular fever and to rule out other illnesses such as tonsillitis, and that antibiotics will not be given because glandular fever is caused by a virus.

In young adults, Lab Tests Online UK says an effective diagnosis can be made from a single blood sample during the acute phase of the disease.

No preparation is needed. Blood is taken from a vein in the arm, and some clinics use a rapid finger-prick style assay that gives a result in minutes. The sample is usually reported together with a full blood count, because glandular fever often changes the white cell picture.

A positive Monospot together with typical symptoms is the basis for diagnosing infectious mononucleosis. Lab Tests Online UK adds that an infected person also has a higher white blood cell count with a higher than usual number of atypical lymphocytes. Heterophile antibodies decline after the fourth week of illness and the test becomes negative as the infection resolves.

A negative result means you may not have mononucleosis, or that it is too early in the illness to detect the antibodies; the test may need to be repeated if symptoms continue. Infants and young children, in particular those under four, do not make heterophile antibodies, so more specific viral tests must be used.

If the Monospot is negative but glandular fever is still suspected, doctors can test for IgM and IgG antibodies to the viral capsid antigen, IgM to the early antigen and IgG to the nuclear antigen. VCA IgM is only present in the few weeks after infection, whereas IgG can be found later, in recovery. These tests can show whether someone is susceptible to EBV, has had a recent infection, has had EBV in the past or has a reactivated infection. Antibody tests for cytomegalovirus or Toxoplasma gondii may be added, since these can cause a similar illness.

Most people recover without treatment. The NHS says you should start to feel better within 2 to 4 weeks, advises rest, fluids and painkillers such as paracetamol or ibuprofen, and says to avoid strenuous activity such as heavy lifting or contact sport. Complications are uncommon but include an enlarged or ruptured spleen, liver inflammation and low platelets.

Call 999 if you cannot swallow even saliva, have severe difficulty breathing or have severe stomach pain; call NHS 111 for difficulty or pain swallowing or breathing. See a GP for a sore throat that is not improving or extreme exhaustion.

EBV spreads through saliva, so kissing and sharing cups can pass it on. Lab Tests Online UK says the virus remains inactive in a few cells for life and can reactivate without symptoms, and that there is no laboratory evidence that EBV causes chronic fatigue syndrome, although feeling very tired during the illness and for a month or two afterwards is normal. The NHS says you can return to work or school once you feel better.