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About CDC's Dengue Branch

Dengue in Puerto Rico

Puerto Rico map The Dengue Branch of the U.S. Centers for Disease Control and Prevention is located in San Juan, Puerto Rico. Although travel-associated dengue and limited outbreaks do occur in the continental United States, most dengue cases in U.S. citizens occur as a result of endemic transmission in some of the U.S. territories, such as Puerto Rico.


The Dengue Branch, located in San Juan, Puerto Rico, provides global leadership in dengue risk assessment, research and effective public health practices. More than 50 million cases of dengue occur annually and 2.5 billion people live in areas at risk. For over 30 years, the Branch has investigated outbreaks and collected, analyzed, and reported dengue cases from Puerto Rico, the U.S. Virgin Islands, and the continental U.S. The Branch processes up to 15,000 specimens annually as the clinical diagnostic laboratory in Puerto Rico, and also serves as the primary reference laboratory for state health departments and the World Health Organization.

As a designated WHO/PAHO Collaborating Center for Dengue and Dengue Hemorrhagic Fever Reference and Research, the Dengue Branch detects and subtypes dengue viral strains; provides quality control services for serological and virological diagnostic tests obtained by national public health laboratories in the Americas; maintains prototype and reference strains of dengue viruses; assists in training on the clinical management of dengue infections and on laboratory techniques necessary for virus isolation, molecular characterization, diagnosis, and related procedures routinely used in the investigation of suspected cases of dengue fever; and participates in outbreak investigations of dengue/dengue hemorrhagic fever (DHF). The Dengue Branch has been actively developing and pilot testing training materials for health care providers to better identify, diagnose and treat dengue cases. The Dengue Branch also provides technical assistance in all aspects of dengue prevention and control.

Mosquito vectors of dengue virus and West Nile virus (WNV) are investigated from a population biology perspective to understand the key ecological factors involved in vector-borne disease transmission and to develop preventive and control measures. The Dengue Branch has capabilities to identify mosquito species and employs Geographical Information Systems, remote sensing, and multivariate statistical techniques to understand the spatial and temporal patterns of vectors and disease.

The Dengue Branch facilitates projects to stimulate the development, improvement and implementation of new strategies and interventions to improve our understanding of dengue progression and pathogenesis.

Summary of Activities and Projects:

The Dengue Branch mission is supported by four activities: Epidemiology, Molecular Diagnostics, Serologic Diagnostics and Entomology-Ecology.

The Epidemiology Activity at the Dengue Branch designs projects and studies to help identify ways to better describe the impact of dengue infections in Puerto Rico, and to reduce intra-household spread of dengue virus infections, and medical complications and case fatality rates. Projects include: implementation and evaluation of a train-the-trainer program to instruct healthcare providers on the clinical management of dengue infections, design of hospital-based surveillance systems for suspected dengue cases; implementation of enhanced dengue surveillance systems at two hospitals in Puerto Rico (PR); and an evaluation of the true economic burden of dengue infections in PR in terms of the cost of hospitalization and clinic visits.

Molecular research in the Dengue Branch is focused on understanding the molecular basis of interferon antagonism in flavivirus infections and in developing bioassays to measure it. These research efforts help identify the molecular basis for virulence and attenuation. The Molecular Diagnostics Activity is also evaluating more sensitive, non-PCR, genome-based rapid diagnostic assays that can be used to more accurately diagnose dengue early in the course of the disease.

The Serologic Diagnostics Activity provides confirmatory diagnostic testing, sequencing and reference material for dengue worldwide, assists WHO in standardizing dengue testing, determines host and viral factors of the pathogenesis of dengue, evaluates new dengue diagnostics for early detection and development of differential diagnostic techniques, and develops quality control samples for proficiency in dengue testing.

The Entomology-Ecology Activity conducts field investigations to improve dengue vector surveillance and control. New devices to capture and eliminate Aedes aegypti mosquitoes are being developed and tested. Social, environmental, and entomological factors are integrated from an ecological perspective to explain dengue transmission. Because of environmental change and urbanization, the scientists are investigating the role of autochthonous mosquitoes as dengue virus vectors and reservoirs. In addition, the scientists collaborate and consul with domestic and international vector-borne disease control organizations and scientific societies.

The impact of the Dengue Branch activities is manifold. Translating new technology into real-time, rapid diagnosis will assist health care providers to identify and treat patients earlier thus improving disease outcomes. Improving surveillance mechanisms will allow for more effective and targeted public health response to dengue outbreaks, as well as a clearer picture of the burden of disease in Puerto Rico, the continental U.S. and internationally. Piloting mosquito control interventions would allow the CDC to make recommendations to vector control programs throughout the region where dengue is endemic. Providing training to healthcare professionals may improve their ability to prevent dengue in their communities and identify patients with dengue infections so that more timely follow-up and treatment can be given in order to prevent medical complications. Improving the quality of surveillance data and capturing the full spectrum of clinical disease allows for better data to conduct studies to improve our understanding of dengue virus.