Zika cases in the United States
- Prior to 2014, very few travel-associated cases of Zika virus disease were identified in the United States.
- In 2015 and 2016, large outbreaks of Zika virus occurred in the Americas, resulting in an increase in travel-associated cases in US states, widespread transmission in Puerto Rico and the US Virgin Islands, and limited local transmission in Florida and Texas.
- In 2017, the number of reported Zika virus disease cases in the United States started to decline.
- Since 2018, there have been no reports of Zika virus transmission by mosquitoes in the continental United States.
- Since 2019, there have been no confirmed Zika virus disease cases reported from United States territories.
- Zika virus disease became a nationally notifiable condition in 2016 but could be reported voluntarily starting in 2015. Cases are reported to CDC by state and local health departments using standard case definitions.
*Includes confirmed and probable disease cases
**Locally acquired cases reported from Florida and Texas in 2016 and 2017
†Includes cases acquired through other routes (e.g., sexual and laboratory transmission)
††Since 2019, all locally acquired cases of Zika in the U.S. territories were diagnosed by antibody testing. Since antibodies against Zika virus can persist for years after infection, serology cannot distinguish between a recent or past infection. Additionally, Zika and dengue virus antibodies cross-react, making it difficult to diagnose which virus is the cause of the current illness. Since 2019, there have been no confirmed Zika virus disease cases reported from U.S. territories.
Publications summarizing Zika virus disease cases reported to CDC from US states and territories
Hennessey MJ, Fischer M, Panella AJ, Kosoy OI, Laven JJ, Lanciotti RS, Staples JE. Zika virus disease in travelers returning to the United States, 2010-2014. Am J Trop Med Hyg. 2016 Jul 6;95(1):212-5.
Walker WL, Lindsey NP, Lehman JA, et.al. Zika Virus Disease Cases – 50 States and the District of Columbia, January 1-July 31, 2016. MMWR Morb Mortal Wkly Rep. 2016 Sep 16;65(36):983-6.
Hall V, Walker WL, Lindsey NP, et.al. Update: Noncongenital Zika Virus Disease Cases – 50 U.S. States and the District of Columbia, 2016. MMWR Morb Mortal Wkly Rep. 2018 Mar 9;67(9):265-269.
Adams LE, Martin SW, Lindsey NP, et.al. Epidemiology of dengue, chikungunya, and Zika virus disease in the US States and Territories, 2017. Am J Trop Med Hyg 2019;101(4);884‒890.