Vincent Fusco died Thursday morning at a hospital in Freehold.
Fusco's mother, Grace Fusco, died Wednesday night, hours after another son, Carmine Fusco, died in Pennsylvania.
A sister, Rita Fusco-Jackson, died last Friday.
19 other family members have been tested, but they're waiting on results now after they were all at a family dinner together in the past several weeks.
There are 11 siblings in this family. Besides the four who died, at least one other is on life support.
"It's like the second we start to grieve about one, the phone rings and there's another person gone, taken from us forever," one family member said. "We're just begging for help. We never want to get that call anytime soon, ever again because of this."
This family's heartbreak is an example how gatherings and one simple family dinner can have deadly consequences.
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