The U.S. Centers for Disease Control and Prevention (CDC) issued an advisory on June 25 to notify healthcare providers, public health authorities, and the public of an increased risk of dengue virus infections in the United States. This year, global cases of the mosquito-borne viral illness have been the highest on record.

This alert follows a similar warning from the World Health Organization (WHO) last month, and coincides with the growth of a specific breed of mosquitoes that carry the four different viruses that spread dengue fever in the U.S., as CMM previously reported.

Countries in the Americas have reported a record-breaking number of dengue cases, exceeding the highest number ever recorded in a single year. Through the beginning of the year until June 24, countries in the Americas reported more than 9.7 million dengue cases—which is twice as many as reported in the entirety of 2023 (4.6 million cases), the CDC said.

In the United States, Puerto Rico has declared a public health emergency, reporting 1,498 cases this year. Additionally, a higher-than-expected number of dengue cases have been identified among U.S. travelers—745 cases from Jan. 1 to June 24. Last year, 1,829 travel-associated cases were reported in the U.S., according to the CDC, which is the highest number on record.

Dengue symptoms are usually fever, headache, fatigue, nausea, vomiting, rash, and body aches. Dengue becomes deadlier the more times a human is infected. With increased global and domestic incidence of dengue, the CDC recommended healthcare providers promote mosquito bite prevention, increase suspicion of dengue, use appropriate diagnostic tests, and report cases of dengue quickly.

While dengue is the most common arboviral disease globally, the virus has been relatively rare in the U.S. Only a handful of outbreaks have occurred in locally transmitted cases in states with warmer climates that are habitat friendly to the specific mosquitos that carry dengue, such as Florida, Texas, Hawaii, and Arizona, CNN reported. Last year, California reported its first locally transmitted case. Other U.S. areas with frequent dengue transmission include American Samoa, the U.S. Virgin Islands, the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau.

Currently no dengue vaccine is recommended for travelers or adults. In Puerto Rico, the public health departments will vaccinate children aged 9 to 16 years with a previous lab-confirmed case who live in areas with frequent transmission, CNN reported.

Last month, the WHO cleared a new dengue vaccine for global approval and another vaccine is being used in several countries in the Americas, European Union, and Asia, Reuters said.

As CMM previously reported, the WHO also recently reported that insufficient data is available on the actual and potential impacts of climate change on malaria and neglected tropical diseases, such as dengue.

The U.S. Environmental Protection Agency (EPA) recommended residents in the Great Lakes region to be prepared for wildfire smoke this summer. The EPA advised residents to stay informed about local air quality and put plans in place to reduce their exposure to wildfire smoke and protect their health.

 “Although big wildfires may be hundreds—if not thousands—of miles away, recent years have taught us that we need to be ready for severe smoke in the Great Lakes region,” said Debra Shore, EPA regional Administrator. “Knowing what you can do to reduce smoke exposure helps families breathe easier and stay healthy.”

Summer wildfires in the U.S. and Canada are becoming bigger and more frequent, the EPA cautioned. Last summer, Canada experienced a record number of wildfires, producing smoke that caused unhealthy air quality and led to widespread health advisories across the Great Lakes region and the entire U. S. Already this year, wildfires in western Canada prompted air quality alerts and warning across several states, as CMM previously reported.

The EPA suggested the following steps to safeguard from smoke and air pollution during a wildfire:

• If you do not have an air conditioner and it is too warm to stay indoors with closed windows, seek shelter with friends or relatives, or at a local public building with air conditioning such as a movie theater, mall, library, or local clean air shelter.
• Keep a supply of N95 or P100 respirators to wear if you go outside when air quality is unhealthy. Respirators can help prevent the inhalation of soot and fine particles in smoke.
• Consider buying a portable air cleaner (avoid technologies that generate ozone) or make a DIY air cleaner.
• Learn how to adjust your HVAC system or air conditioner to keep smoke out, and consider buying a high-efficiency (e.g., MERV-13) HVAC filter.
• Replace filters according to manufacturer recommendations, typically every 60-90 days or earlier if they are heavily soiled.
• Ensure children, older adults, pregnant people, and people with asthma or other lung or heart conditions have at least five days’ worth of medication and food on hand to avoid going outside.
• People with asthma or other lung or heart conditions may consider developing a medical action plan in consultation with a healthcare provider along with an evacuation plan if heavy smoke persists for several days.

EPA offers resources for the public to monitor air quality conditions and forecasts in real time. The AirNow Fire and Smoke map provides information on fire locations, smoke plumes, near real-time air quality, and protective actions to take. Air quality alerts can be accessed through EnviroFlash, the AirNow website, and the AirNow app. The U.S. Centers for Disease Control and Prevention also recommends following the Air Quality Index (AQI). Additionally, states often provide air quality websites and detailed local information and forecasts.