Last Friday, July 29, the Department of Health confirmed the first local transmissions of the Zika virus in four individuals.

The continental United States has 1,658 confirmed Zika cases as of July 27, according to the U.S. Centers for Disease Control and Prevention (CDC). However, all of these cases have been a result from traveling abroad. These patients have either contracted the disease from abroad or from having intercourse with a person who has traveled to Zika-affected areas.

On the other hand, the four individuals who were recently confirmed positive with the Zika Virus were the first documented cases of local transmission within the continental United States. They haven't been to Zika-affected areas. Reports say that the four individuals, one woman and three men, were from Miami-Dade and Broward Counties.

CDC Director Thomas Frieden mentioned in a news briefing held on Aug. 1 that mosquito control measures in Miami haven't been that effective. Frieden stated three possible reasons for the ineffectiveness of their measures. Firstly, mosquitoes could be resilient to the insecticides they've used. Secondly, there could be small breeding grounds around the urban area where mosquitoes carrying the virus can continue to breed. Lastly, in a big urban environment like Miami, mosquito control is simply a very difficult task.

Last Thursday morning, Miami-Dade County officials began an aerial spraying of insecticide over a 10-square-mile area of the county, reports CNN. Frieden announced that they will continue to do resistance testings to determine whether or not the mosquitoes are resilient to the insecticides being used.

The director advised pregnant women to avoid traveling to the areas that are positive with the Zika virus. The virus is known for causing microcephaly, a birth defect that gives infants a head that is smaller than usual. According to Frieden, a direct mosquito bite can cause devastating birth defects, even among women who don't show symptoms. He also advised families and couples to take the extra measures to protect themselves from mosquitoes. Frieden urged pregnant women who have traveled to Zika-infected areas on or after June 15 to get tested for Zika.