The number of coronavirus cases at the Essex County jail more than doubled overnight, after advocates and inmates complained the sheriff hasn't done enough to stop the spread of virus.

Thursday, the Essex County Sheriff’s Department reported 13 inmates, three guards and one contractor have tested positive for the coronavirus. On Wednesday, the total was eight.

“It’s just a human petri dish,” said inmate Daniel Mahoney, 35, of Quincy, in an interview with WBUR. He’s awaiting trial and detained in a dormitory room with 30 other men at the Essex jail.

He said he sleeps in a bunkbed just feet away from half a dozen others. A couple days ago inmates were given cloth masks and told to wear them unless they were in a bunk or cell, he added.

“They collected them to wash them, and people got masks back that definitely weren't theirs,” Mahoney said. “People were getting masks back with blood still on the strap that goes around the head and like mucus, and they were soaking wet still.”

Kevin Coppinger, sheriff at the Essex County jail in Middleton. (Jesse Costa/WBUR)

Essex County Sheriff Kevin Coppinger wasn’t available for comment, but a spokesperson said safety is the top priority and that they’d replace any soiled masks.

Mahoney said even if someone was sick, he doubts guards and medical staff would listen.

“The attitude is you guys are being overdramatic,” he said.

Essex is one of several jails WBUR highlighted in a series called “Dying on the Sheriff’s Watch,” that found inmates in medical distress often were ignored or not believed even as their illnesses turned into emergencies.

The Essex County Sheriff’s Department wouldn’t tell WBUR how many coronavirus tests it has on hand or how many inmates have been tested. Medical care at the jail is provided by Wellpath Holdings Inc., the nation’s largest corrections healthcare company.

Just last week inmates got packages of goodies that included a Danish pastry, coffee, Doritos, Ramen noodles, shampoo and toothpaste, Mahoney said. He said he wanted soap or disinfectant.

“There was really nothing there that's going to help us keep clean,” he said.

Elizabeth Matos, executive director of Prisoners’ Legal Services, has heard similar complaints from inmates at Essex. She said social distancing at the jail is impossible.

“People are still living in dormitory settings in Essex,” Matos said. “They’re still sharing common bathroom sinks, toilets, showers, still eating together in congregate settings.”

As of Thursday, a total of 19 inmates have tested positive in Massachusetts jails and 33 guards and other staff, based on tracking by WBUR.

Sheriffs across Massachusetts have been pressured to release inmates who are elderly, non-violent or awaiting trial. Last week the Supreme Judicial Court ruled that some pre-trial inmates can have release hearings to try to reduce the spread of the virus.

WBUR's Deborah Becker contributed to this report