A Utah resident who died after contracting Zika from travel abroad may have spread the virus to a family contact who did not leave the country, raising troubling questions about a possible new route of transmission of the mosquito-borne virus, state and federal officials said Monday.
Officials said they are investigating how the second person became infected. One possibility is close contact between the critically ill patient and the contact. Officials are also trapping and testing mosquitoes around both individuals' homes. The second person has since recovered, officials said.
“We’re learning something new about Zika virus every day,” said Erin Staples, an epidemiologist with the Centers for Disease Control and Prevention during a press conference with Utah state health department officials on Monday. The CDC team is helping Utah with the investigation. The Utah case “appears to be unique,” she said, but many questions remain.
The elderly resident's death in late June was the first Zika-related adult death in the continental United States. The individual had an underlying health condition before testing positive for the virus, Salt Lake County health department officials said. The exact cause of death was not determined.
Zika is spread primarily through the bite of an infected Aedes aegypti or Aedes albopictus mosquito, but county officials have said neither species is present in their area. The virus can also be spread through sex. About 80 percent of infected individuals have no symptoms, while the rest tend to experience only mild problems that last for several days to a week.
Symptoms include mild fever, skin rash, conjunctivitis ("pink eye"), muscle and joint pain, malaise or headache.
In rare cases, though, the virus has been linked to a nervous system disorder that can cause muscle weakness and sometimes paralysis. It poses its biggest danger during pregnancy, when infection can cause a range of severe fetal abnormalities.
In April, the CDC reported the first U.S. adult death from Zika in a patient in Puerto Rico. That man, who was in his 70s, died from internal bleeding after developing severe thrombocytopenia -- a rare immune reaction to his infection that causes low levels of blood-clotting platelets.
As of July 13, no cases of locally transmitted, mosquito-borne Zika have been reported in the continental United States. As of July 13, a total of 1,305 cases of travel-associated Zika have been reported in the 50 states and District of Columbia. Federal, state and local officials are preparing for the possibility of local spread of Zika.