Infectious mononucleosis(mono) is a contagious infection caused mainly by theEpstein-Barr virus(EBV).
Typically, the virus is spread through bodily fluids, especially saliva.
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Is Mono Contagious?

Oliver Rossi / Getty Images
When Is Mono Contagious?
Although mono is contagious, it is spread primarily through contact with saliva of an infected person.
As soon as a person becomes infected with EBV, they can pass it on to others.
The larger the viral load, the more contagious a virus is.
How Long Is Mono Contagious?
Incubation Period
In people with mono, theincubation periodranges widely.
Active Infection Period
A person can also spread the infection while they’re showing symptoms.
The time span of when a person feels ill can also vary.
During this time, it’s possible for you to still pass it on to others.
They are designed to look for antibodies produced by the immune system in response to EBV.
They will likely order tests to see to it that another infection isn’t to blame for your symptoms.
Although CAEBV is rare, it can be serious and thus requires prompt medical treatment.
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Kimura H, Cohen JI.Chronic active Epstein-Barr virus disease.Front Immunol.2017 Dec 22;8:1867. doi:10.3389/fimmu.2017.01867