Travel surveillance uncovers dengue virus dynamics and introductions in the Caribbean.

Dengue is the most prevalent mosquito-borne viral disease in humans, and cases are continuing to rise globally. In particular, islands in the Caribbean have experienced more frequent outbreaks, and all four dengue virus (DENV) serotypes have been reported in the region, leading to hyperendemicity and increased rates of severe disease. However, there is significant variability regarding virus surveillance and reporting between islands, making it difficult to obtain an accurate understanding of the epidemiological patterns in the Caribbean. To investigate this, we used travel surveillance and genomic epidemiology to reconstruct outbreak dynamics, DENV serotype turnover, and patterns of spread within the region from 2009-2022. We uncovered two recent DENV-3 introductions from Asia, one of which resulted in a large outbreak in Cuba, which was previously under-reported. We also show that while outbreaks can be synchronized between islands, they are often caused by different serotypes. Our study highlights the importance of surveillance of infected travelers to provide a snapshot of local introductions and transmission in areas with limited local surveillance and suggests that the recent DENV-3 introductions may pose a major public health threat in the region.

Travel surveillance uncovers dengue virus dynamics and introductions in the Caribbean.

Dengue is the most prevalent mosquito-borne viral disease in humans, and cases are continuing to rise globally. In particular, islands in the Caribbean have experienced more frequent outbreaks, and all four dengue virus (DENV) serotypes have been reported in the region, leading to hyperendemicity and increased rates of severe disease. However, there is significant variability regarding virus surveillance and reporting between islands, making it difficult to obtain an accurate understanding of the epidemiological patterns in the Caribbean. To investigate this, we used travel surveillance and genomic epidemiology to reconstruct outbreak dynamics, DENV serotype turnover, and patterns of spread within the region from 2009-2022. We uncovered two recent DENV-3 introductions from Asia, one of which resulted in a large outbreak in Cuba, which was previously under-reported. We also show that while outbreaks can be synchronized between islands, they are often caused by different serotypes. Our study highlights the importance of surveillance of infected travelers to provide a snapshot of local introductions and transmission in areas with limited local surveillance and suggests that the recent DENV-3 introductions may pose a major public health threat in the region.

Rapid detection of influenza A and B viruses in clinical specimens by Light Cycler real time RT-PCR.

BACKGROUND: the influenza viruses cause morbidity and mortality annually among children and elderly. Surveillance and rapid diagnosis is imperative in the reference laboratory, as clinical symptoms are insufficient for proper diagnosis. OBJECTIVES: this study involved the design of a rapid detection method for influenza A and B viruses using real time RT-PCR from clinical specimens. Methods were specifically designed for use on the Light Cycler. The sensitivity and specificity were also to be determined. STUDY DESIGN: the identification and discrimination of influenza A and B viruses employs two dual probe systems based on fluorescence resonance energy transfer (FRET) technology. Following submission by physicians participating in the Florida sentinel influenza network, 58 specimens were chosen for testing using both tissue culture and Light Cycler methods. RESULTS: of the 35 identified positive for influenza virus via tissue culture isolation, the Light Cycler results matched identification and typing with 100% agreement. However, the Light Cycler recognized 16 additional specimens that were positive for the presence of the virus. RT-PCR and nucleotide sequencing confirmed the presence of influenza A virus in these specimens. Using tenfold serial dilutions, the sensitivity of the Light Cycler method was determined to be 0.01 TCID50. The lower limit of RNA detection was determined as 1.6 x 10(-7) microg for influenza A virus, and 1.2 x 10(-7) microg for influenza B virus. Specificity of the Light Cycler method was determined by testing specimens containing adenovirus, parainfluenza virus and echovirus, all of which yielded negative results with no discernible background. CONCLUSIONS: overall, this newly developed method of simultaneous detection and typing of influenza types A and B using the Light Cycler proves to be more sensitive than tissue culture isolation, with corresponding specificity. This technique may be valuable for surveillance and rapid identification of influenza for early diagnosis.