Puerto Rico Declares Public Health Emergency


Rising dengue incidence in Puerto Rico signals broadening health concerns.

Mosquito | Image credits: Unsplash

After a surge in dengue cases, Puerto Rico's health officials announced a public health emergency on March 25th, 2024. The US territory has seen at least 549 instances of the mosquito-transmitted illness this year, a significant difference from the 1,293 cases reported in 2023. Before, the most recent dengue epidemic in Puerto Rico before this was in 2012.

“Dengue is common in Puerto Rico,” according to the Centers for Disease Control and Prevention (CDC). “The risk of getting dengue while living in Puerto Rico is high.”1

Over the last 2 decades, there has been a tenfold increase in dengue fever cases, surpassing 5 million globally in 2023. The disease is now affecting a broader geographic area, challenging regions previously unfamiliar with dengue management to deal with its outbreaks. The escalation in dengue cases and its increasing burden on public health have shifted attention towards a disease that can no longer be solely classified as "tropical," a change attributed to climate variations.

Main Takeaways

  1. Puerto Rico faces a significant public health challenge with a notable surge in dengue cases, leading to the announcement of a public health emergency in March 2024.
  2. Over the past 2 decades, there has been a dramatic global increase in dengue fever cases, with the disease now affecting broader geographic areas beyond traditional tropical climates.
  3. For individuals in or traveling to affected areas, particularly Puerto Rico, the CDC recommends several preventive measures against the Dengue virus, including EPA-approved insect repellents and protective clothing.

Previous reporting by Contagion states, “This alarming rise in one of the most concerning vector-borne diseases is attributable to a few key factors, several of which are interconnected. It is easiest to understand these trends through the lens of One Health, a framework that considers environmental, ecological, and human health as an integrated whole.4 In other words, the health of the planet and all living systems directly influences threats to human health, and vice versa. The One Health framework is especially pertinent when considering vector-borne diseases, as insect behavior and evolution add a layer of complexity to disease dynamics and ecology.”2

For US travelers planning to go to Puerto Rico, the CDC encourages practicing usual precautions against the Dengue virus (DENV). They suggest travelers should take preventive measures such as applying an Environmental Protection Agency-approved insect repellent, wearing long-sleeved shirts and pants outdoors, and ensuring accommodations are either air-conditioned or equipped with window screens, or sleeping under a bed net treated with insecticide.

The dengue virus vaccine, Dengvaxia, is not approved for US travelers who are visiting but not living in areas where dengue is endemic. Annually, as many as 400 million individuals contract the dengue virus. Around 100 million cases result in illness, with severe dengue leading to approximately 40,000 deaths. Dengvaxia is authorized for children between ages 9 through 16 who have previously had a laboratory-confirmed dengue infection and reside in regions where dengue is prevalent, including certain US territories and associated states.

“In people who have not already been infected with DENV, Dengvaxia can increase the risk for severe illness and hospitalization if the person gets dengue after vaccination. Serodiagnostic tests with acceptable performance (≥75% sensitivity and ≥98% specificity) recommended by health authorities are available to test people for evidence of previous dengue,” according to the CDC. “Only people who test positive for previous DENV infection or who have other laboratory-confirmed evidence of a previous DENV infection are eligible for vaccination with Dengvaxia. 3 other dengue vaccines are currently undergoing phase 3 clinical trials.”3

The likelihood of contracting the dengue virus escalates with the length of stay and the prevalence of the disease in the destination, particularly during local outbreaks or the rainy season. Regardless of their duration of stay, travelers visiting tropical regions should remain conscious to prevent mosquito bites by employing various protective measures.

The recent dengue epidemic in Puerto Rico highlights the ongoing challenge of this mosquito-transmitted disease. This situation emphasizes the need for a public health approach that integrates environmental, ecological, and human health to combat the threat of dengue fever.


  1. CDC. Living in Puerto Rico? What You Need to Know About the Dengue Vaccine. Published November 1, 2023. Accessed March 28, 2024. https://www.cdc.gov/dengue/vaccine/parents/eligibility/need-to-know.html
  2. Parr, L. Rising Dengue Fever Cases Carry One Health Implications. Contagion. Published March 26, 2024. Accessed March 28, 2024. https://www.contagionlive.com/view/rising-dengue-fever-cases-carry-one-health-implications
  3. Abene, S. CDC Issues Crucial Guidance for Travelers to Dengue-Endemic Regions. Contagion. Published January 31, 2024. Accessed March 28, 2024. https://www.contagionlive.com/view/cdc-issues-crucial-guidance-for-travelers-to-dengue-endemic-regions
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