What to know
- Zika virus disease (Zika) is a nationally notifiable condition.
- There is no current local transmission of Zika virus in the continental United States.
- Since 2019, there have been no confirmed Zika cases reported from US territories.
- No mosquito-borne transmission of Zika virus has ever been reported in Alaska and Hawaii.
Background
- Prior to 2014, very few travel-associated cases of Zika 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 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 cases reported from US territories.
- CDC is notified of cases by state and local health departments using standard case definitions.
Zika cases by year
Data are preliminary and subject to change. Data are current as of November 19, 2024.
| Year | US States Locally acquired |
US States Travel-associated† |
US Territories Locally acquired†† |
US Territories Travel-associated |
|---|---|---|---|---|
| 2024 | 0 | 18 | 9 | 0 |
*Confirmed and probable disease cases
†Cases acquired through other routes (e.g., laboratory transmission) are classified as travel-associated for reporting.
††Since 2019, all locally acquired cases of Zika in the US 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 US territories.
2023 data are preliminary and subject to change. Data are current as of November 19, 2024.
| Year | US States Locally acquired |
US States Travel-associated† |
US Territories Locally acquired†† |
US Territories Travel-associated |
|---|---|---|---|---|
| 2015 | 0 | 62 | 9 | 1 |
| 2016 | 224‡ | 4,944 | 36,367 | 145 |
| 2017 | 7‡ | 445 | 665 | 1 |
| 2018 | 0 | 74 | 147 | 1 |
| 2019 | 0 | 28 | 73 | 1 |
| 2020 | 0 | 4 | 57 | 0 |
| 2021 | 0 | 2 | 32 | 0 |
| 2022 | 0 | 5 | 17 | 0 |
| 2023 | 0 | 7 | 30 | 0 |
*Confirmed and probable disease cases
†Cases acquired through other routes (e.g., laboratory transmission) are classified as travel-associated for reporting.
††Since 2019, all locally acquired cases of Zika in the US 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 US territories.
‡Locally acquired cases reported from Florida and Texas in 2016 and 2017
- Hennessey MJ, Fischer M, Panella AJ, et al. Zika Virus Disease in Travelers Returning to the United States, 2010-2014. Am J Trop Med Hyg. Jul 6 2016;95(1):212-5. doi:10.4269/ajtmh.16-0049
- 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. Sep 16 2016;65(36):983-6. doi:10.15585/mmwr.mm6536e5
- 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. Mar 9 2018;67(9):265-269. doi:10.15585/mmwr.mm6709a1
- Adams LE, Martin SW, Lindsey NP, et al. Epidemiology of Dengue, Chikungunya, and Zika Virus Disease in U.S. States and Territories, 2017. Am J Trop Med Hyg. Oct 2019;101(4):884-890. doi:10.4269/ajtmh.19-0309