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SALT LAKE CITY — Nearly 100 people in the Salt Lake County neighborhood where an elderly man died after contracting Zika virus have submitted blood samples for testing, according to public health officials.
Officials launched the investigation last month after the elderly man's son, who had been caring for his father while sick, also contracted the virus.
Health officials say the case is "unique" because the son did not have either of the two known risk factors for Zika: Travel to an affected area or sexual contact with an infected individual.
But they emphasized that the case does not pose a threat to the public. Researchers have no evidence that Zika can be airborne, experts said, nor do officials expect that to be a cause.
Utah Department of Health epidemiologist Dallin Peterson said testing is ongoing, but all results have been negative so far.
According to Peterson, health officials went door-to-door to check if other people in the area had been exposed to Zika-carrying mosquitos or had symptoms.
"There were many people that did volunteer and wanted to be tested," he said, adding that many were "comforted" by the offer.
Some evidence exists to suggest that Zika virus can be spread through exposure to infected blood. Officials said the elderly man, who had recently traveled to a Zika-affected country, had an unusually high amount of the virus in his blood.
He died in June — probably the result of a combination of Zika virus and an underlying health condition, health officials said.
Health officials declined to confirm the relationship between the patients or their gender, citing privacy concerns, but the Associated Press reported the relationship.
Concerns about Zika ramped up over the weekend after officials in Florida said they identified 14 people who had likely been infected by local mosquitos — the first known instances of local transmission in the continental U.S.
All of the patients were from one densely populated one-square-mile area of Miami, according to officials. Six of those cases had been identified by door-to-door testing.
The news prompted the Centers for Disease Control and Prevention to issue its first travel warning for a place in the continental U.S. for pregnant women.
CDC Director Tom Frieden said the "moderately high" numbers of Aedes aegypti mosquitos still being found in the area suggests that they may be developing resistance to insecticides or may be hiding out in "cryptic breeding places."
Ary Faraji, manager of the Salt Lake City Mosquito Abatement District, called the arrival of Zika on Florida's shores "huge, huge news" for local mosquito control teams.
"Our control has been geared toward floodwater mosquitos, marshland mosquitos,” Faraji said. “Habitats that are very, very predictable. Habitats that are recurring. Habitats that I have maps of.”
But unlike the West Nile-carrying mosquitos endemic to Utah, Zika-carrying mosquitos tend to thrive in smooth containers in urban areas, Faraji said. That means anything from a birdbath in your backyard to a tire at a salvage yard.
"In Salt Lake City alone there’s 70,000 private residencies," Faraji said. "So logistically and operationally, it’s almost impossible for us to go through every single private residence and make sure they’re dumping out their water."
Experts say the likelihood of local transmission in Utah is low. Zika is primarily spread by the Aedes aegypti mosquito, which experts do not believe can survive Utah's cold winters.
Faraji said he is more concerned about the Aedesalbopictus mosquito, which has survived as far north as Boston and has been known to carry Zika.
Part of the difficulty in combating Zika is how much public health officials are still learning about the disease, according to Faraji. Zika has been linked to severe birth defects in babies and to a rare autoimmune disorder known as Guillain–Barré syndrome. Researchers also believe that sexual transmission may be playing a bigger role in the spread of Zika than previously thought.
"So many unique things about Zika virus are just mind-boggling to us as scientists and etymologists," Faraji said. These are just completely new territories for us."
Another issue is funding. Both the House and Senate left for their summer recess without coming to an agreement on nearly $2 billion in funding requested by the Obama administration to fight Zika.
Faraji asked the public for its assistance in cleaning up standing water and reporting potential mosquito habitats to their local mosquito abatement district.
Unlike the West Nile-carrying mosquitos endemic to Utah, Zika-carrying mosquitos tend to thrive in urban areas because they like smooth containers, human blood and daytime biting, Faraji said.
"Most [local mosquitos] bite at dawn and dusk," Faraji said. "The fact that you were bit during the day should be alarming to the general public."
Mosquito abatement workers have increased surveillance of the neighborhood where the now-deceased Utah man and his son lived. So far no Aedes aegypti or albopictus mosquitos have been found, according to Faraji, nor has the virus been detected in any of Utah's local mosquitos.
Health department officials hope to release the results of the investigation by early September. An emergency CDC team deployed to assist in the investigation has left the state, officials said.
Contributing: Ladd Egan, Ashley Moser
