On the other hand, the absence of swollen cervical lymph nodes and fatigue are the most useful to dismiss the idea of infectious mononucleosis as the correct diagnosis. The insensitivity of the physical examination in detecting an enlarged spleen means it should not be used as evidence against infectious mononucleosis. A physical examination may also show petechiae in the palate. Heterophile antibody test
The heterophile antibody test, or monospot test, works by agglutination of red blood cells from guinea pigs, sheep and horses. This test is specific but not particularly sensitive (with a false-negative rate of as high as 25% in the first week, 5–10% in the second, and 5% in the third). About 90% of diagnosed people have heterophile antibodies by week 3, disappearing in under a year. The antibodies involved in the test do not interact with the Epstein–Barr virus or any of its antigens.The monospot test is not recommended for general use by the CDC due to its poor accuracy. Serology
Serologic tests detect antibodies directed against the Epstein–Barr virus. Immunoglobulin G (IgG), when positive, mainly reflects a past infection, whereas immunoglobulin M (IgM) mainly reflects a current infection. EBV-targeting antibodies can also be classified according to which part of the virus they bind to:

Viral capsid antigen (VCA):Anti-VCA IgM appear early after infection, and usually, disappear within 4 to 6 weeks.
During this study, treatment with satralizumab reduced the number of NMOSD relapses by 74% in participants who were anti-AQP4 positive compared to treatment with a placebo (inactive treatment).A study of satralizumab as an adjuvant to immunosuppressant treatment for NMOSD included 76 adult participants; 52 were anti-AQP4 positive. Immunosuppressant treatment in combination with satralizumab reduced the rate of relapses in participants who were anti-AQP4 positive by four-fifths compared to immunosuppressant treatment alone.The U.S. Food and Drug Administration (FDA) approved satralizumab based on evidence from two clinical trials (Trial 1/ NCT02073279 and Trial 2/NCT02028884) of 116 participants with NMOSD who were anti-aquaporin-4 (AQP4) antibody positive. The trials were conducted at 62 sites in the United States, Canada, Europe and Asia. Participants received at random either satralizumab or placebo injections according to the schedule. Neither the participants nor the healthcare providers knew which treatment was being given. In the second trial, all participants were also receiving their current immunosuppressive medications for the treatment of NMOSD. The benefit of satralizumab was evaluated by measuring the time to the first attack and comparing it to placebo.There was no evidence of a benefit in participants who were anti-AQP4 antibody negative in either trial. Society and culture
Legal status
Satralizumab was approved for the treatment of AQP4-IgG-seropositive NMOSD in Canada, Japan, and Switzerland.Satralizumab was approved for medical use in the United States in August 2020. The U.S. Food and Drug Administration (FDA) granted the application for satralizumab fast track and orphan drug designations.