Kiss

Getting mono is a gift and a curse. On the one hand, it suggests you have people to kiss; on the other, it means your body has fallen prey to mononucleosis, the “kissing disease.” For some people, this diagnosis is worse than others, leading to effects such as fatigue, sore throat, fever, and other flu-like symptoms that last for two to four weeks and can even warrant a visit to the hospital. In a paper published Tuesday in the open-access journal mBio, scientists reveal how some people manage to avoid the worst parts of the romance-killing illness.

In the paper, a team of researchers at University of Massachusetts Medical School and the University of Nebraska reveal that the severity of a person’s mono experience has to do with how particular cells in their immune system react to the infection.

Mono is caused by the Epstein-Barr virus, which is transmitted through saliva. And despite the pejorative nickname, you can get mono in other ways besides kissing, like sharing a drink with someone. Noting that all this spit-swapping has different effects on everyone, the researchers investigated how people’s immune systems “remember” previous mono infections and, therefore, respond more strongly to future infections.

Mono: sucks more for some people.

To conduct this research, they investigated the blood makeup of 32 people who tested positive for Epstein-Barr virus and compared them to 17 healthy control subjects. In particular, they were looking at participants’ T-cells, the parts of the immune system that learn to recognize certain pathogens when they first enter the body and know to target them as invaders the next time they show up. In this study, the researchers searched for T-cells that “remembered” both influenza A, which causes the flu, and the Epstein-Barr virus — cells they call “cross-reactive.”

People who have experienced more severe symptoms from their mono infections, it turns out, carry 25 times more cross-reactive T-cells than the healthy controls, and people who have had only mild cases of mono had 10 times more.

the kiss
If you don't want to give up kissing, one way to avoid severe mono cases is to get a flu shot.

In many illnesses, nasty symptoms are not caused by the virus itself, but rather, it’s the body’s immune response to the virus, which can include raising the internal temperature to kill off invaders (fever) and funneling blood into a certain area to provide resources (swelling). It makes sense, in this case, that someone who has a stronger immune response would feel sicker.

As the current study and previous research show, the immune response to one disease can also be mediated by your exposure to another. In this case, since the T-cells in people who get sicker are cross-reactive between Epstein-Barr virus and influenza A, it appears that, if you get the flu at some point, your immune cells will remember and your case of mono could be worse.

“These results suggest that an individual’s history of infection … may help to explain variations in human disease thought previously to be only due to genetic differences, the physiological condition of the patient, or the inoculation route and dose used,” write the authors.

So what can you do to help protect yourself against a debilitating case of mono if you get infected with the Epstein-Barr virus? Get your flu shot! If you have cross-reactive T-cells, you’ve got a better chance of evading a severe immune response if you’ve avoided catching the flu.