In an interview, Tyler Sharp, acting chief epidemiologist at CDC's Dengue Branch in San Juan, Puerto Rico, said the man had a rare autoimmune condition that has been linked to Zika virus infections in other countries hit by the epidemic. The condition, known as ITP, immune thrombocytopenic purpura, has also been associated with other infectious diseases, Sharp said.
In cases involving Zika infections, people develop antibodies to the infection and then the "antibodies are directed against the platelets, and they get destroyed, and bleeding increases," Sharp said.
Although Zika virus-associated deaths are rare, "the first identified death in Puerto Rico highlights the possibility of severe cases, as well as the need for continued outreach to raise health care providers' awareness of complications that might lead to severe disease or death," the CDC report said.
Colombia has reported three deaths of people infected with Zika who also had ITP. The cases in Colombia involved an infant girl, a 30-year-old woman, and a 72-year-old woman. All were hospitalized and died last October. There has also been one case involving a 54-year-old woman who had been living in the Netherlands but got bitten by infected mosquitoes when she visited her native Suriname in January 2016. French Polynesia also reported four cases during its outbreak of Zika from 2013 to 2014.
Sharp said the man presumably was bitten by an infected mosquito and was hospitalized. He had no other serious or potentially life-threatening health conditions, Sharp said.
Sharp said health officials are also investigating other potential cases of ITP related to Zika infections.
Zika virus infections have been confirmed to cause microcephaly and a host of other birth defects. There is also strong evidence linking Zika to Guillain-Barré syndrome, another autoimmune disorder that can cause paralysis and in rare cases, death.
Puerto Rico has been the part of the United States hit hardest by Zika. The island has 707 confirmed Zika cases, including 89 pregnant women. More than 6,000 people have been tested and about 11 percent of them, 683 people, had Zika. CDC officials have said they estimate that 700,000 people — about 20 percent of the population — could be infected across the island by the end of the year, based on previous outbreaks of dengue and chikungunya, related viral diseases.