A 5-year-old Venezuelan migrant boy who became ill at a migrant shelter in Chicago before Christmas and then passed away died from sepsis and a bacterial infection that causes strep throat, an autopsy released Friday shows.

Jean Carlos Martinez Rivero tragically died on Dec. 17 with a case of Group A Strep, which can cause strep throat and other life-threatening illnesses, according to an autopsy released by the Cook County Medical Examiner’s Office. Sepsis can lead to serious complications in as little as 24 hours. 

Martinez was a resident at a warehouse retrofitted as a shelter in Chicago’s Pilsen neighborhood when he returned to the building with his family and suffered a medical emergency. About 2,300 people had been staying at the Pilsen shelter, near downtown.

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Despite immediate first aid by shelter staff, which included chest compressions, Martinez Rivero died at Comer Children’s Hospital, according to FOX 32. Contributing factors in his death were listed as COVID-19, adenovirus and rhinovirus.

Martinez came from Venezuela to Chicago with his family about a month before he died, according to ABC7.

The boy’s death revived concerns about conditions at shelters and questions about how Chicago was responding to an influx of people unaccustomed to the city’s cold winters and with few local contacts. Chicago and other northern U.S. cities have struggled to find housing for tens of thousands of asylum-seekers, many of whom have been bused from Texas throughout the last year.

At the time of his death, the space had about 10 isolation rooms for when people get sick, Dr. Evelyn Figueroa told Fox 32.

“These are hard environments for people to rest and feel good and be able to take care of themselves,” said Figueroa, who toured the building and runs a nearby food pantry and has spent most of her medical career working with homeless, immigrant and low-income populations.

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Chicago Mayor Brandon Johnson released a statement early Saturday expressing his condolences.

This is a tragic loss, and we appreciate the work of community partners supporting the Martínez Rivero family during this difficult time,” Johnson said.

“The City of Chicago coordinates medical screenings for all shelter residents, weekly on-site provider support, on-site vaccination events for COVID, varicella, and flu, and partnerships with a network of community health centers for other healthcare needs.” 

“All shelter residents are offered comprehensive medical examinations and care.”

More than 35,000 migrants have been transported to Chicago and its suburbs over the past year and a half. Despite this influx, recent data from the city indicates a decline in the number of migrants staying at shelters, with figures dropping to their lowest point in months, according to Fox 32 Chicago.

Earlier this month, hundreds of asylum-seekers still awaited placement at airports and police stations in Chicago, some of them still camped on sidewalks outside precinct buildings.

As of Tuesday, the number of migrants in shelters has fallen below 13,000, marking a decrease from peaks observed in mid and early January, when the count reached nearly 15,000.

The autopsy report comes just days after the state of Illinois and Cook County announced plans to allocate up to an additional $252 million to house, feed and provide other services to illegal immigrants arriving in Chicago this year.

The Associated Press contributed to this report.