Dengue Epidemic in Puerto Rico? What Should Visitors and Residents Know


Puerto Rico declared a dengue public health emergency with 549 cases this year, up from 1293 in 2023. What should visitors and residents know to protect themselves?

Dengue virus    (Adobe Stock 66723556 by

Dengue virus

(Adobe Stock 66723556 by

The Puerto Rico Health Department has declared a public health emergency due to the 549 reported cases on the island so far this year. For comparison, in 2023, there were 1293 total cases.

So, what should residents and visitors know about dengue?

The report said, “In response to the situation of the spread of the dengue virus in Puerto Rico so far this year, the secretary of the Department of Health, Carlos Mellado López, issued a public health emergency declaration for dengue. With this action, he said, it will be possible to guarantee the necessary resources to strengthen surveillance, detection, prevention, vector control, and clinical management, among other efforts, in order to address the spread of this disease with the promptness and efficiency it deserves.”

Speaking with Infection Control Today, Matthew Pullen, MD, an assistant professor of medicine in the Division of Infectious Diseases and International Medicine at The University of Minnesota Medical School, Minneapolis, Minnesota, and member of the ICT's Editorial Advisory Board, said, "When traveling to a region with endemic Dengue or an ongoing outbreak, like we're seeing in Puerto Rico, the main focus should always be on prevention. There is no specific treatment for this virus, and subsequent infections after the first episode are at higher risk for severe or fatal disease, so prevention goes a long way. Strategies like using insect repellent, wearing lightweight, long-sleeved clothing (sun shirts, for example), and staying in areas where mosquito control methods are being used can all greatly reduce your risk of infection. If you have had confirmed dengue in the past, there is also 1 US-approved vaccine that can potentially help prevent reinfection. This vaccine is relatively new and infrequently available, so it's recommended to consult with your primary care physician and/or public health offices about this vaccine."

A Message from Sharon Ward-Fore, MS, MT(ASCP), CIC, FAPIC, ICT's Recipient of the ICT's 2023 Educator of the Year

Puerto Rico has recently seen at least 549 cases of Dengue, a mosquito-transmitted illness, prompting Puerto Rico's health officials to announce a public health emergency on March 25th, 2024. The risk of contracting Dengue in Puerto Rico is high; however, the CDC currently does not have any travel notices for Puerto Rico.

Dengue is spread to people through the bite of an infected mosquito. Mosquitoes that spread dengue virus bite during the day and night. These same mosquitoes also spread chikungunya and Zika viruses. Experts say the best way to prevent these diseases is to protect yourself from mosquito bites.

Plan for Travel

4-6 weeks before travel

  • Review country-specific travel recommendations, health notices, and warnings.
  • Visit a travel clinic or your healthcare provider for pre-travel medical care.
  • Pack an Environmental Protection Agency (EPA)-registered insect repellent. Use this EPA link to find the insect repellant that’s right for you:
  • Because Dengue is spread through mosquito bites, prevent mosquito bites to reduce your risk of getting dengue or other vector-borne viruses like chikungunya or Zika.
  • Pack acetaminophen (known as paracetamol outside of the United States), not aspirin or ibuprofen, in your first aid kit. These medications can be used to manage fever and body pain in case you get dengue.

During Your Trip:

  1. Follow steps to prevent mosquito bites to protect yourself and your family.
  2. Stay in places with air conditioning and window/door screens.
  3. Use a bed net if air conditioned or screened rooms are not available or if sleeping outdoors.
  4. See a health care provider if you develop a fever or have symptoms of dengue.

After Your Trip:

  1. Protect yourself from mosquito bites.
  2. Even if you do not feel sick, travelers returning from an area with a risk of dengue should take steps to prevent mosquito bites for 3 weeks so they do not spread dengue to mosquitoes that could spread the virus to other people.

The bottom line is people living in or traveling to areas with a risk of dengue should take steps to avoid mosquito bites.


Dengue: Plan for Travel. CDC. May 17, 2022. Accessed April 2, 2024.

Traveler’s Health Notices, Puerto Rico

Dengue, a mosquito-borne disease, is a serious health threat. It is caused by 4 virus types: dengue 1, 2, 3, and 4. This illness is prevalent in Puerto Rico, where the risk of infection is notably high, with individuals potentially experiencing dengue up to four times in their lives. While there's no specific treatment for dengue, it can be life-threatening, especially in severe cases that require hospitalization.

“This year, dengue cases have exceeded historical figures. The teams have been working on the integrated plan for prevention and control in response to arboviruses and we will expand the implemented response. It is important to highlight that the increase in cases has not only been reflected in Puerto Rico, but we have seen it throughout the entire region of the Americas,” said Mellado LópezIn efforts to combat dengue, a vaccine called Dengvaxia has been developed, offering protection against future dengue illness, hospitalization, and severe disease. Approved by the Food and Drug Administration in 2019 for children aged 9–16 with prior laboratory-confirmed dengue infections, the vaccine has been deemed safe and effective. Eligible individuals reside in regions where dengue is prevalent, including US territories such as Puerto Rico and the US Virgin Islands, along with associated states such as the Federated States of Micronesia, the Republic of Palau, and the Republic of the Marshall Islands. Testing to confirm a previous dengue infection is required before administering the vaccine to prevent an increased risk of severe illness for those without prior exposure.

In an Infection Control Today interview, Thomas Rademacher, MD, PhD, cofounder and CEO of Emergex, also the emeritus professor of molecular medicine at the University College London, London, England, said, “Dengue fever is caused by the mosquito-borne virus, dengue, a single positive-stranded RNA virus that can be grouped into 4 genetically- and antigenically-related viruses, known as serotypes 1–4, prominent in tropical and subtropical areas.”

He continued, “Approximately half of the world’s population (~3.9B) live in areas with a risk of dengue, which is often a leading cause of illness endemic to these areas; this population does not even include travelers from nonendemic countries, contributing overall to a high-in-demand market for protection against dengue infection. Mild dengue fever causes a high fever and flu-like symptoms, whereas severe dengue fever can be life-threatening within a few hours and often requires hospital care. Dengue is one of the most critical mosquito-borne viral diseases, with up to 400 million people worldwide infected with the dengue virus each year.

Over the past few decades, the global incidence of dengue has seen a staggering rise, as reported cases to the World Health Organization (WHO) surged from 505,430 in 2000 to 5.2 million by 2019. However, these figures likely underestimate the true burden of the disease, with many cases being either asymptomatic or mild and managed without medical intervention. Additionally, misdiagnoses with other febrile illnesses further contribute to the underreporting of dengue cases.

Estimates from various studies paint a grave picture of the prevalence of dengue, with one model suggesting a staggering 390 million infections annually, of which 96 million result in clinical manifestations.

The threat of dengue extends globally, with more than 100 countries across WHO Regions in Africa, the Americas, the Eastern Mediterranean, South-East Asia, and the Western Pacific now facing endemic levels of the disease. Particularly hard-hit regions include the Americas, South-East Asia, and the Western Pacific, with Asia bearing around 70% of the global disease burden. Notably, the disease is encroaching into new territories, with reports of local transmission surfacing in Europe, including instances in France and Croatia in 2010, as well as imported cases detected in other European nations. The unprecedented scale of the disease was evident in 2019, marking the highest number of reported cases globally, with transmission even reaching Afghanistan for the first time. The Americas alone accounted for 3.1 million cases, including over 25,000 classified as severe, while significant numbers were reported in Asian nations such as Bangladesh, Malaysia, the Philippines, and Vietnam. As of 2021, dengue remains a pressing concern in countries like Brazil, Colombia, the Cook Islands, Fiji, India, Kenya, Paraguay, Peru, the Philippines, the Reunion Islands, and Vietnam.

Finally, Mellado López stressed in the statement that "it is essential to recognize symptoms early, such as fever, headache, muscle and joint pain, skin rashes, and fatigue, since they could be indicative of dengue. In the presence of any of these symptoms "It is recommended to seek medical attention immediately."

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