CLEARWATER — Health officials on both sides of Tampa Bay are scrambling to contain a potential new outbreak of the Zika virus after the first locally transmitted infection was confirmed in Pinellas County Tuesday.

The Florida Department of Health is planning to conduct door-to-door testing and outreach in the neighborhood where the infection was detected. However, officials do not plan to reveal the location unless more cases are discovered.

The effort to track down people who had contact with the infected person, known as an epidemiological investigation, will also extend into Hillsborough County, officials said. Targeted mosquito spraying to limit the spread of the virus is also taking place both in Pinellas and at an undisclosed Hillsborough County location.

Gov. Rick Scott announced the new infection, the first locally transmitted case of the virus confirmed outside South Florida, at a Zika roundtable with Pinellas County health officials and political leaders Tuesday.

"This person did not travel to an infected area with Zika; we are looking at a number of locations," Scott said. "Hopefully something good will happen and it will just be a single case. But if we do find out, what we will do is we will be very aggressive."

No information was released about the infected resident who Scott referred to as "she." Dr. Celeste Philip, the state surgeon general, said the resident likely contracted the virus, which is also sexually transmitted, through a mosquito bite.

Yet, the state does not believe mosquitoes are actively spreading Zika in the county. That won't be known for certain until the state's investigation is complete, which could take a week or more.

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It was 11 days after the first non-travel related cases in Miami-Dade County emerged before health officials on July 29 confirmed that mosquitoes were transmitting the virus in the Wynwood neighborhood, north of downtown Miami.

Since then, the number of non-travel cases in Florida has risen to 42, although officials say through testing and mosquito abatement they have cleared 76 blocks of Wynwood, reducing the area where mosquitoes are spreading the virus to about half a square mile.

Investigations into five cases in Miami-Dade and Palm Beach counties concluded that mosquitoes were not the source of those infections.

Health officials are expected to investigate the Pinellas case by retracing the patient's recent steps, talking to co-workers and testing family members, said Philip, the surgeon general. She said the fact that officials can't find any evidence of local ongoing transmission is reassuring.

"When we have multiple cases, it is easier because we can often find mosquito breeding sites," she said. "In this case, we do our investigation, ask questions. ... But if we don't find additional people that are positive, we may never find out where that case occurred."

U.S. Rep. David Jolly, R-Belleair Bluffs, said he understood the surgeon general's caution about revealing the location but said it could increase anxiety in Pinellas residents, especially expectant mothers and women planning a family.

"I think it's important we know what the risk is to Pinellas County, including if there is a risk of mosquito-borne transmission in any part of the county," he said. "That is a public health issue."

The presence of one Zika case in Pinellas is likely the harbinger of more, said José Montero, an associate professor at the University of South Florida's Division of Infectious Disease and International Medicine.

"I think it will be like what we're seeing in Miami Beach, where we have a few cases," Montero said. "There's never just one. I hope it's just a few. This is something the whole Gulf Coast is concerned about."

The most likely way the virus arrived was via an infected South Florida resident traveling to Pinellas and either being bitten by a mosquito or passing the virus on through intercourse, Montero said. About 80 percent of infected people exhibit no symptoms, meaning they go about their normal routine instead of being home bound and largely quarantined.

While Zika can be harmless to many humans, it can be devastating for fetuses.

It has been linked to birth defects including microcephaly, or babies born with small heads. It is the first virus known to be spread by mosquitoes and to be sexually transmitted.

Just hours after Scott announced the Pinellas case, Rachael Marken, who is eight months pregnant with her first child, a boy, headed to the health department's office on Ulmerton Road. She arrived with her mom, Chrissy Marken, to get tested.

"I've been freaked out ever since I got pregnant and learned about the Zika," said Marken, 24. "I'm telling myself that it's going to come back negative."

Her mom reassured her: "It will."

Satanna Woolfolk, of Dunedin, also showed up at the Ulmerton Road office Tuesday, having read online about the health department's free Zika tests.

"I had to get here," said Woolfolk, 26, who is 34 weeks pregnant with her second child, a girl. "I've been staying inside since I heard about the virus."

Blood samples from the health department tests are sent to a state lab for testing. Results can take from one to three weeks.

Alarm about Zika has increased throughout the year, said Dr. Mary Ashley Cain, an assistant professor at the University of South Florida.

Zika was already "hitting close to home," she said. Now it's even closer. She spends most days caring and checking up on prenatal patients from Hillsborough and Pinellas counties at USF's clinic. She tells them not to panic, but to be smart.

Information about the Pinellas Zika case and travel safety was added to the Visit St. Petersburg-Clearwater website on Tuesday.

David Downing, executive director of the organization, Pinellas County's tourism marketing bureau, said the Rio Olympics had shown that visitors will not necessarily stay away, provided they are given good information to make a decision.

"You walk a little bit of a tightrope," Downing said. "You don't overreact and you don't under-react."

If health officials confirm that mosquitoes are spreading Zika in Pinellas, the state would likely identify a small area in the county where they believe the virus is concentrated. Aedes aegypti, the mosquito that spreads the virus, only flies about 150 meters in its lifetime, making it theoretically possible to contain an outbreak.

Pinellas mosquito control specialist Rob Krueger said his mission hasn't changed with the discovery of the new case. It is still about educating the public on how to stop mosquitoes from breeding.

"We will keep up that effort as long as it takes," he said. "A lot of our efforts are over 14-hour days to make sure we get the job done."

The Pinellas County Health Department has clinics at 205 Dr. Martin Luther King Jr. St. N in St. Petersburg, 310 N Myrtle Ave. in Clearwater and 8751 Ulmerton Road in Largo.

Scott said health officials have tested nearly 4,000 people around the state and have the capacity to test about 6,500 more.

The state is also giving out Zika prevention kits that include insect repellent, condoms and mosquito nets.

State health officials and Pinellas County Mosquito Control have started "aggressive" mosquito spraying, Scott said.

Scott has set aside emergency funds totalling $26 million to aid in Zika prevention and response, including $5 million for Miami-Dade to combat Zika announced Monday. As of Aug. 12, Pinellas County had received $106,036 from the state for Zika.

"If there are (more) local needs, we will surely look at that," Scott said.

The U.S. Centers for Disease Control and Prevention has spent more than $8 million to fight Zika in Florida, as well as about $27 million in emergency preparedness funding that the federal government says can be used for Zika response.

Times staff writers Colleen Wright and Sara DiNatale contributed to this report. Contact Christopher O'Donnell at codonnell@tampabay.com or (813) 226-3446. Follow @codonnell_Times.