Will Texas Encounter Dengue Outbreaks in 2024

The global outbreak of dengue has significantly increased over the past two decades. From 2000 to 2019, the World Health Organization (WHO) documented a ten-fold surge in dengue cases.

According to the WHO Disease Outbreak News (DON498) published on December 21, 2023, this year's dengue upsurge has been characterized by a significant increase in the scale and simultaneous occurrence.

Moreover, the mosquito-transmitted disease impacts regions previously unaffected by dengue as the range of Aedes aegypti and Aedes albopictus mosquitoes increases.

In 2023, the Pan American Health Organization and the WHO have confirmed over 4.1 million dengue cases in the Region of the Americas. Dengue has quietly become the most widespread arbovirus and causes the highest number of arboviral disease cases in the Americas.

Approximately 500 million people living and visiting the Americas are at risk of dengue infection. 

In the Americas, only Canada is free from the vector of dengue. 

Furthermore, underdeveloped surveillance systems may have led to missed identification of symptoms, contributing to increased severe dengue outcomes in unsuspecting people, says the WHO.

Dengue virus has four serotypes. Infection with one serotype provides immunity to the same serotype and only transient immunity to the other serotypes, after which secondary infections with a different serotype increase the risk for severe dengue.

Shortages of dengue diagnostic kits for early detection and untrained clinical staff exasperated dengue outbreak detection.

The U.S. CDC has confirmed over 2,200 dengue cases in the United States in 2023 and recommends dengue virus testing for anyone who lives in or has traveled to areas where the dengue virus is transmitted and has recently experienced signs and symptoms of dengue illness.

In the U.S., the leader in dengue reporting is Florida, which has confirmed 518 travel-associated dengue cases, most from Cuba, and 187 locally acquired dengue cases, primarily in Miami-Dade County this year.

In contrast, the state of Texas has only reported 39 dengue cases in 2023.

This imbalance is highlighted given Texas's geographic location next to dengue-endemic Mexico and various Central American countries.

Several Texas laws require specific information regarding notifiable conditions to be provided to the Texas Department of State Health Services (DSHS). 

The mosquito that transmits dengue fever is found in Texas, so there is a potential risk for dengue transmission. Sporadic outbreaks have occurred in extreme south Texas.

"There was dengue circulating, and we had no idea that it was here (Texas) because we just weren't looking," commented Dr. Kristy Murray of the Baylor College of Medicine and Texas Children's Hospital in an NPR article written by Thomas Andrew Gustafson on October 17, 2023.

Because a blood test diagnoses dengue, healthcare providers must rule out various similar illnesses, including malaria, yellow fever, influenza, viral hepatitis, typhoid, Rift Valley fever, and leptospirosis, says DSHS.

This review process may be the reason behind DSHS's current arbovirus reporting pattern.

Dengue prevention can include vaccination since two vaccines are now in use globally. In the U.S., Dengvaxia® is a live attenuated tetravalent chimeric vaccine approved by the U.S. FDA.

However, Dengvaxia's use requires a diagnostic test to confirm prior infections.

The CDC has been empowering a test rollout strategy in Puerto Rico for the past few months, with results and insights expected in 2024.