Twenty-eight people are now dead after contracting listeria infections tied to contaminated cantaloupe, federal health officials reported Tuesday.

A total of 133 people have been sickened by the outbreak, which continues to claim victims more than a month after fresh, whole melons grown and packed at Jensen Farms in Holly, Colo., were recalled, the Centers for Disease Control and Prevention said.

Dirty equipment, poor sanitation and bad storage techniques were blamed for the outbreak, which has led to illnesses in 26 states, federal Food and Drug Administration officials announced last week. Members of Congress have asked Jensen Farm owners to appear at a staff briefing likely scheduled for next week and to bring all relevant documents from the outbreak.

Deaths tied to the listeria-tainted cantaloupe have been reported in a dozen states, including seven in Colorado, five in New Mexico, three in Kansas, two each in Louisiana, Missouri, New York and Texas and one each in Indiana, Maryland, Nebraska, Oklahoma and Wyoming. Four illnesses were related to pregnancy, with one illness diagnosed in a newborn and one miscarriage reported.