Peru's 2023 Dengue Outbreak: The Largest on Record, Reaching Even Lima

Dengue is nothing new in Peru. It is endemic, and from 2017 to 2022 the country reported between 4,698 and 68,290 cases a year, mostly in the north. But in March 2023 cases rose sharply, and by the end of July Peru had its largest dengue outbreak on record — one that reached deep into metropolitan Lima, where locally acquired dengue had been rare.

The size of it

From January 1 to July 29, 2023, Peru reported 222,620 dengue cases — 139,366 confirmed and 83,254 probable — about ten times the previous five-year average, and 381 deaths.

The coastal northwestern departments hit hardest had also suffered in the 2017 outbreak, and were drenched in early March 2023 by extreme rainfall linked to Cyclone Yaku. Lima, with about 11 million people, saw far more cases than in past years, including in neighborhoods that had never reported dengue. Incidence was highest among 12- to 17-year-olds (807 per 100,000), and 55 percent of cases were female.

Who died

The overall case fatality ratio was 0.17 percent, but risk climbed steeply with age:

The most deaths were in Piura (130), Lambayeque (115) and Ica (52); deaths occurred in 16 of Peru's 25 jurisdictions.

Testing and the virus

A network of 49 public health laboratories ran more than 200,000 tests in 2023. Of 14,462 cases with a known serotype, DENV-2 (49 percent) and DENV-1 (49 percent) dominated, with DENV-3 at 2 percent. All four dengue viruses have circulated in Peru, where transmission usually peaks between November and May.

The response

Peru's Ministry of Health, regional health offices and international partners stepped up surveillance and targeted mosquito control — larvicide in standing water and insecticide spraying in affected neighborhoods. Clinical surveillance units with staff trained in dengue care were set up in outbreak areas, hospitals put up triage tents for patients with fever, and training was offered to clinicians nationwide.

The lesson

Dengue is a growing threat worldwide, pushed by rapid urbanization, travel and climate change. Outbreaks can arrive abruptly and overwhelm health systems. The report calls for rapid detection, preparedness and stronger primary care, and for vaccines and effective, scalable mosquito control.

Sources

Based on "Notes from the Field: Dengue Outbreak — Peru, 2023," by César V. Munayco and colleagues from Peru's Ministry of Health and National Institute of Health and CDC, Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain.