For most of us, a mosquito bite is a nuisance; an itch that won’t go away for several days. But with recent mosquito-born Zika transmissions, we’re being faced with the reality that mosquitoes are actually a real danger. As of November 3, 26 babies in the United States have born with birth defects related to Zika, and five pregnancy losses were caused by Zika.

With more than 30,000 confirmed cases of Zika in the U.S., people have naturally been concerned about the virus, how it spreads, and how to protect themselves. Most U.S. cases were travel related, but the first case of the virus spread by a mosquito occurred in late July of 2016 in Miami, Florida.

Florida has taken the hardest hit. Every state has reported travel-borne cases, but Florida is the only state with locally-acquired cases, at 139 as of November 2.

Three areas of Florida (1 square mile of Wynwood neighborhood in Miami, 4.5 square miles of Miami Beach, and 1-square mile area in Miami-Dade County) have been identified as having mosquito-spread Zika virus between August and October.

The Wynwood area has since been deemed to be safe, but the other two areas still are not. In fact, the 4.5 square miles of Miami Beach originally began as 1.5 square miles and was later expanded.

How Does Zika Spread?

While the disease can be spread sexually, mosquitoes, specifically the Aedes aegypti mosquito, are the primary source of transmission of the Zika virus. Zika virus spreads through infected people, circulating in blood, semen, saliva, and urine. Mosquitoes become infected when they feed on a person with the virus, and they then infect others in subsequent feeds. An infected pregnant woman can pass Zika to her developing baby.

The Aedes aegypti mosquito also spreads chikungunya and dengue, and they are aggressive daytime biters.

How Zika Is Tracked

Finding a Zika-carrying mosquito might be as difficult as the proverbial needle in a haystack, according to CDC Director Dr. Tom Friedan. Fortunately, it isn’t necessary to find that mosquito to determine the impact of the Zika virus. It can certainly help, but the CDC can confirm local mosquito transmission without the culprit in hand.

The Department of Health (DOH) regularly updates the public with cases of Zika. If one case is reported, it doesn’t mean an active transmission is occurring. DOH investigates the case by sampling close contacts and other community members in the area in an effort to find out if additional people have been infected. In addition, they are active in mosquito abatement and reduction activities. As of November 2, the DOH believed ongoing transmission is not taking place outside the small areas of Wynwood and Miami Beach in Miami-Dade County.

In September, the Wynwood neighborhood had been free of Zika for 45 days, and was taken off the list of affected areas. In addition, fewer mosquitoes were found in traps in the area.

The CDC believes this reduction is because of efforts to eliminate mosquitoes in the area, including aerial spraying of the pesticide naled and a larvicide that uses mosquito-killing bacteria. Local residents have protested against the use of pesticides, but the county will continue spraying.

Pregnancy and Zika

In most people, Zika causes mild symptoms like rashes and joint pain. The main threat, however, is to pregnant women because the virus can cause permanent brain damage to a developing baby.

Because of this, all county health departments in Florida are offering free Zika risk assessments and testing for pregnant women.

While it is not considered a widespread transmission, pregnant women are still advised to avoid travelling to the impacted areas in Miami-Dade County. Pregnant women who live in the area are advised to protect themselves against mosquito bites by wearing repellent and clothing that covers the skin, and limiting their time outdoors.

All pregnant women who reside in or travel frequently to the affected area should be tested for Zika in their first and second trimesters, according to the CDC.

If a pregnant woman has a history of the Zika virus, she should receive additional ultrasounds throughout the pregnancy.

Prevention of Zika

The DOH urges residents to drain water weekly, no matter how small. Mosquitoes breed in standing water, and even a bottle cap of water can attract mosquitoes.

Repair holes in your screens, use repellents when outdoors, and wear clothing that covers your skin when spending time outdoors.