Notes from the Field: Early Evidence of Locally Acquired Dengue Virus Infection—Maricopa County, Arizona, November 2022

Melissa Kretschmer, MA1; Jennifer Collins, MPH1; Ariella P. Dale, Ph.D.1; Brenna Garrett1; Lia Koski, MPH1; Karen Zabel, MSN1; R. Nicholas Staab, MD1; Katie Turnbow1; Judah Nativio, MS1; Kelsey Andrews1; William E. Smith, MS1; John Townsend2; Nicole Busser2; james go2; Kathryn Burr, DMV1,3,4; Forrest K. Jones, PhD4.5; Gilberto A. Santiago, PhD5; Kelly A. Fitzpatrick, MSPH5; Irene Ruberto, PhD3; Kathryn Fitzpatrick, MPH3; Jessica R. White, DrPH1; Laura Adams, DVM5; Rebecca H. Sunenshine, MD1,6 (See authors’ affiliations)

See Suggested Quote

Views :

Views equals page views plus PDF downloads

On November 7, 2022, dengue fever virus (DENV), which is not endemic to the continental United States (1), was identified in a resident of Maricopa County, Arizona, by reverse transcription-polymerase chain reaction (RT-PCR) testing at the Arizona State Public Health Laboratory (ASPHL). The patient (Patient A) was admitted to hospital on October 19 with a dengue-like illness, 7 days after traveling and staying in Mexicali, Mexico for less than 4 hours. Patient A was hospitalized for 3 days and then recovered. The Maricopa County Environmental Services Department (MCESD) performed retrospective testing for DENV in samples collected from 21 mosquito pools located within 5 miles of Patient A’s residence from October 1 through November 3. A sample taken from a mosquito pool (Pool A) on October 5 was positive for DENV. Whole genome sequencing by the Dengue Branch of the CDC later revealed that closely related DENV-3 strains not known to be circulating in the patient’s region of travel had been identified in both patient A and in group A, suggesting local transmission of DENV.

Based on a pre-existing joint response plan from the Maricopa County Public Health Department (MCDPH), MCESD, and the locally acquired Arizona Department of Health Services against mosquito-borne diseases, the MCDPH and MCESD activated an Incident Command Office on November 10. ) prioritized prospective investigations of health care provider and laboratory reports of DENV and suspected arbovirus visits queried with the National Syndromic Surveillance Program (BioSense)* BioSense platform; 2) retrospectively reviewed confirmed, probable and suspected dengue cases investigated between July 1 and November 10 for evidence of local DENV transmission; 3) alerted health care providers of possible local transmission; and 4) advised providers to test and report suspected DENV to MCDPH. No evidence of local acquisition was identified in 13 suspected arbovirus visits identified in the Biosense database, 10 closed case reviews, and 10 new case investigations. MCESD retrospectively tested samples collected from September 18 through November 19 from 4,299 additional mosquito pools located throughout the county, including mosquito pools within 5 miles of Patient A’s residence collected during the period. extended test, for DENV by RT-PCR; all were negative. This activity has been reviewed by the CDC and was conducted in accordance with applicable federal law and CDC policy.

After discussions with the Dengue branch of the CDC and Florida Public Health (2,3) regarding current best practices for managing locally acquired DENV infections, from November 17-19, MCDPH and MCESD surveyed residences within a 0.09 mile (150 m) radius (4) from the residence of patient A and pool A to interview residents, collect human samples for DENV testing, and assess mosquito breeding properties. The teams approached 241 households; residents of 72 households (29.9%) consented to EAs, and 73 people in 59 (24.5%) households were interviewed. Of these 73 respondents, 12 (16.4%) reported onset of dengue-like symptoms within 14 days of their interview and were tested; all results were negative for DENV by RT-PCR at ASPHL. A serum enzyme immunoassay for the DENV immunoglobulin M test was performed by ASPHL on blood samples from 53 (72.6%) respondents; of these, one (1.9%) result was positive. The Arboviral Diseases Branch of the CDC confirmed DENV-3 by a plaque reduction neutralization assay. The person with the positive test result has not reported any travel in the 2 weeks prior to the onset of symptoms. One of this person’s household members reported dengue-like symptoms but declined testing; both have since recovered. Environmental assessment of this residence identified Temples of the Egyptians mosquitoes and breeding places; mosquitoes collected in a BG-Sentinel professional mosquito trap§ tested negative for DENV by RT-PCR. The outbreak (composed of two autochthonous DENV infections) ended on January 4, 2023, after more than 45 days without additional locally acquired cases, as indicated by the most recent guidelines (4).

Coordinated surveillance and response activities identified the first locally acquired human DENV infections in Maricopa County, Arizona. Established partnerships and pre-existing plans were essential to mount a rapid and coordinated response to non-endemic arbovirus transmission. MCDPH and MCESD will strengthen future surveillance activities to identify and prevent autochthonous transmission of DENV, including installing additional mosquito traps around patient residences and raising public awareness about preventing mosquito exposure. A county-wide healthcare provider education campaign is being implemented to educate providers about local DENV transmission and encourage testing for patients with compatible disease, regardless of history of travel.


Blanca Caballero, Maricopa County Department of Environmental Services; Angela Moreth, Nicholas Moyte, Sonia Singh, Maricopa County Public Health Department Office of Communications and Marketing; Maricopa Medical Reserve Corps, Maricopa County Department of Public Health Office of Preparedness and Response; Guillermo Adame, Richard Turner, Arizona Department of Health Services; Arizona State Public Health Laboratory; Dengue Directorate, CDC; Arboviral Diseases Branch, CDC; Andrea Morrison, Danielle Stanek, Florida Department of Health; Maricopa County survey participants.

County team members

Cindy Bitcon, Adam Costello, Kathie Dumais, Gurminder Singh Gill, Michael Hagan, Sierra Lamb, Jayme Lee, Georgina Marin, Jason Nelson, Patti O’Neil, Cayla Grace Sullivan-Land, Karli Taylor, June Vutrano, Darby Watters-Roybal, Kyle Willman, Maricopa County Department of Public Health, Preparedness and Response Field Team; Hector Abundis, Dan Armijo, Luis Avalos, Kara Cox, Eric Garcia, Bruce McKinzey, Yunior Osorio Mulet, Jacob Rivera, Maricopa County Department of Environmental Services Vector Control Division Field Team; Luis Avalos, Trinity Johnson, Adele Malone, Yunior Osorio Mulet, Adela Riehle, Maricopa County Department of Environmental Services Vector Control Division Laboratory.

1Maricopa County Department of Public Health, Phoenix, Arizona; 2Maricopa County Environmental Services Vector Control, Phoenix, Arizona; 3Arizona Department of Health Services; 4Epidemic Intelligence Service, CDC; 5Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC; 6Career Epidemiology Field Officer Program, CDC.

The references

  1. CDC. Dengue fever: dengue fever in US states and territories. Atlanta, GA: US Department of Health and Human Services, CDC; 2022. Accessed January 13, 2023.
  2. Radke EG, Gregory CJ, Kintziger KW, et al. Dengue outbreak in Key West, Florida, USA, 2009. Emerg Infect Dis 2012;18:135–7.
  3. Florida Department of Health. Health in Florida: dengue epidemic and serological survey in Martin County. Tallahassee, FL: Florida Department of Health; 2014. Accessed January 24, 2023.
  4. CDC. CDC 2017 Interim Zika Response Plan: May 2017. Atlanta, GA: US Department of Health and Human Services, CDC; 2017. Accessed January 24, 2023.

Suggested citation for this article: Kretschmer M, Collins J, Dale AP, et al. Notes from the field: First Evidence of Locally Acquired Dengue Virus Infection – Maricopa County, Arizona, November 2022. MMWR Morb Mortal Wkly Rep 2023;72:290–291. DOI:

MMWR And Morbidity and Mortality Weekly Report are service marks of the US Department of Health and Human Services.
Use of trade names and trade sources is for identification purposes only and does not imply endorsement by the US Department of Health and Human Services.
References to non-CDC sites on the Internet are provided as a service to MMWR readers and does not constitute or imply endorsement of these organizations or their programs by the CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of the pages found on these sites. URLs listed in MMWR were current as of the date of publication.

All HTML versions of MMWR articles are generated from final proofs by an automated process. This conversion may result in character translation or formatting errors in the HTML version. Users are referred to the PDF electronic version ( and/or the original MMWR hard copy for printable versions of official text, figures and tables.

Questions or messages regarding formatting errors should be directed to

Leave a Comment