Could it be a case of Mafia fever?

A juror who on Day One tried to weasel out of the John “Junior” Gotti trial forced a postponement yesterday when she called in sick.

The woman, one of six alternate jurors on the case, initially phoned the court to say she was at her doctor’s office and had experienced a “reaction” to a flu shot, Manhattan federal Judge P. Kevin Castel said yesterday morning.

Castel delayed the start of testimony to wait to hear from her and for the arrival of another alternate juror who had “called in to say he had taken the wrong train and was going to be a few minutes late.”

But an hour later, the judge canceled the day’s proceedings after the woman, who works as a city procurement analyst, reported that she was suffering from a sinus infection.

On Monday, the woman was among seven jurors who sent notes to the judge asking to be excused from Gotti’s racketeering and murder trial.

Her note said: “I am losing money every day by being here. Six weeks is to [sic] long. I just brought [sic] a house and the extra money is helping me pay [for] the house.”

Her request, along with the others, was denied. After summoning the other jurors, Castel didn’t detail the woman’s condition, but said she “has been given a prescription medicine” and “is of the view that she will be fit and ready to serve” this morning.