BACKGROUND: The COVID-19 pandemic underscored the need for rapid and accurate diagnostic tools. In August 2020, the Abbott BinaxNOW COVID-19 Antigen Card test became available as a timely and affordable alternative for SARS-CoV-2 molecular testing, but its performance may vary due to factors including timing and symptomatology. This study evaluates BinaxNOW diagnostic performance in diverse epidemiological contexts. METHODS: Using RT-PCR as reference, we assessed performance of the BinaxNOW COVID-19 test for SARS-CoV-2 detection in anterior nasal swabs from participants of two studies in Puerto Rico from December 2020 to May 2023. Test performance was assessed by days post symptom onset, collection strategy, vaccination status, symptomatology, repeated testing, and RT-PCR cycle threshold (Ct) values. RESULTS: BinaxNOW demonstrated an overall sensitivity of 84.1% and specificity of 98.8%. Sensitivity peaked within 1-6 days after symptom onset (93.2%) and was higher for symptomatic (86.3%) than asymptomatic (67.3%) participants. Sensitivity declined over the course of infection, dropping from 96.3% in the initial test to 48.4% in testing performed 7-14 days later. BinaxNOW showed 99.5% sensitivity in participants with low Ct values (≤ 25) but lower sensitivity (18.2%) for participants with higher Cts (36-40). CONCLUSIONS: BinaxNOW demonstrated high sensitivity and specificity, particularly in early-stage infections and symptomatic participants. In situations where test sensitivity is crucial for clinical decision-making, nucleic acid amplification tests are preferred. These findings highlight the importance of considering clinical and epidemiological context when interpreting test results and emphasize the need for ongoing research to adapt testing strategies to emerging SARS-CoV-2 variants.

PROBLEM/CONDITION: Dengue is the most prevalent mosquitoborne viral illness worldwide and is endemic in Puerto Rico. Dengue's clinical spectrum can range from mild, undifferentiated febrile illness to hemorrhagic manifestations, shock, multiorgan failure, and death in severe cases. The disease presentation is nonspecific; therefore, various other illnesses (e.g., arboviral and respiratory pathogens) can cause similar clinical symptoms. Enhanced surveillance is necessary to determine disease prevalence, to characterize the epidemiology of severe disease, and to evaluate diagnostic and treatment practices to improve patient outcomes. The Sentinel Enhanced Dengue Surveillance System (SEDSS) was established to monitor trends of dengue and dengue-like acute febrile illnesses (AFIs), characterize the clinical course of disease, and serve as an early warning system for viral infections with epidemic potential. REPORTING PERIOD: May 2012-December 2022. DESCRIPTION OF SYSTEM: SEDSS conducts enhanced surveillance for dengue and other relevant AFIs in Puerto Rico. This report includes aggregated data collected from May 2012 through December 2022. SEDSS was launched in May 2012 with patients with AFIs from five health care facilities enrolled. The facilities included two emergency departments in tertiary acute care hospitals in the San Juan-Caguas-Guaynabo metropolitan area and Ponce, two secondary acute care hospitals in Carolina and Guayama, and one outpatient acute care clinic in Ponce. Patients arriving at any SEDSS site were eligible for enrollment if they reported having fever within the past 7 days. During the Zika epidemic (June 2016-June 2018), patients were eligible for enrollment if they had either rash and conjunctivitis, rash and arthralgia, or fever. Eligibility was expanded in April 2020 to include reported cough or shortness of breath within the past 14 days. Blood, urine, nasopharyngeal, and oropharyngeal specimens were collected at enrollment from all participants who consented. Diagnostic testing for dengue virus (DENV) serotypes 1-4, chikungunya virus, Zika virus, influenza A and B viruses, SARS-CoV-2, and five other respiratory viruses was performed by the CDC laboratory in San Juan. RESULTS: During May 2012-December 2022, a total of 43,608 participants with diagnosed AFI were enrolled in SEDSS; a majority of participants (45.0%) were from Ponce. During the surveillance period, there were 1,432 confirmed or probable cases of dengue, 2,293 confirmed or probable cases of chikungunya, and 1,918 confirmed or probable cases of Zika. The epidemic curves of the three arboviruses indicate dengue is endemic; outbreaks of chikungunya and Zika were sporadic, with case counts peaking in late 2014 and 2016, respectively. The majority of commonly identified respiratory pathogens were influenza A virus (3,756), SARS-CoV-2 (1,586), human adenovirus (1,550), respiratory syncytial virus (1,489), influenza B virus (1,430), and human parainfluenza virus type 1 or 3 (1,401). A total of 5,502 participants had confirmed or probable arbovirus infection, 11,922 had confirmed respiratory virus infection, and 26,503 had AFI without any of the arboviruses or respiratory viruses examined. INTERPRETATION: Dengue is endemic in Puerto Rico; however, incidence rates varied widely during the reporting period, with the last notable outbreak occurring during 2012-2013. DENV-1 was the predominant virus during the surveillance period; sporadic cases of DENV-4 also were reported. Puerto Rico experienced large outbreaks of chikungunya that peaked in 2014 and of Zika that peaked in 2016; few cases of both viruses have been reported since. Influenza A and respiratory syncytial virus seasonality patterns are distinct, with respiratory syncytial virus incidence typically reaching its annual peak a few weeks before influenza A. The emergence of SARS-CoV-2 led to a reduction in the circulation of other acute respiratory viruses. PUBLIC HEALTH ACTION: SEDSS is the only site-based enhanced surveillance system designed to gather information on AFI cases in Puerto Rico. This report illustrates that SEDSS can be adapted to detect dengue, Zika, chikungunya, COVID-19, and influenza outbreaks, along with other seasonal acute respiratory viruses, underscoring the importance of recognizing signs and symptoms of relevant diseases and understanding transmission dynamics among these viruses. This report also describes fluctuations in disease incidence, highlighting the value of active surveillance, testing for a panel of acute respiratory viruses, and the importance of flexible and responsive surveillance systems in addressing evolving public health challenges. Various vector control strategies and vaccines are being considered or implemented in Puerto Rico, and data from ongoing trials and SEDSS might be integrated to better understand epidemiologic factors underlying transmission and risk mitigation approaches. Data from SEDSS might guide sampling strategies and implementation of future trials to prevent arbovirus transmission, particularly during the expansion of SEDSS throughout the island to improve geographic representation.

Dengue, the leading cause of arboviral disease worldwide, can be fatal without appropriate treatment. Among 7,528 confirmed or probable travel-associated U.S. dengue cases reported during 2010-2021, one in five (1,474, 20%) was reported in 2019. This is 168% higher than the annual average number of cases reported during 2010-2018 and 2020-2021 (approximately 550 per year) and 61% higher than the 913 cases reported in 2016, the second highest year on record. The number of cases as a fraction of air traffic volume to international destinations outside North America or Europe was also highest in 2019, with 41.9 cases per million trips, compared with 21.0 per million in other years during 2010-2021. This report compares the number and characteristics of travel-associated dengue cases reported to national surveillance in the United States in 2019 with cases reported during 2010-2018 and 2020-2021. Areas with conditions suitable for dengue transmission as well as the population at risk for dengue are expected to increase, placing U.S. travelers at higher risk for infection. Health care providers should be aware that dengue is a common cause of fever in the returning traveler and be familiar with its signs and symptoms, testing, and management. Dengue vaccines are not currently recommended for U.S. travelers; therefore, persons should review areas of dengue risk and follow guidance for preventing mosquito bites.

Puerto Rico has experienced the full impact of the COVID-19 pandemic. Since SARS-CoV-2, the virus that causes COVID-19, was first detected on the island in March of 2020, it spread rapidly though the island’s population and became a critical threat to public health. We conducted a genomic surveillance study through a partnership with health agencies and academic institutions to understand the emergence and molecular epidemiology of the virus on the island. We sampled COVID-19 cases monthly over 19 months and sequenced a total of 753 SARS-CoV-2 genomes between March 2020 and September 2021 to reconstruct the local epidemic in a regional context using phylogenetic inference. Our analyses revealed that multiple importation events propelled the emergence and spread of the virus throughout the study period, including the introduction and spread of most SARS-CoV-2 variants detected world-wide. Lineage turnover cycles through various phases of the local epidemic were observed, where the predominant lineage was replaced by the next competing lineage or variant after approximately 4 months of circulation locally. We also identified the emergence of lineage B.1.588, an autochthonous lineage that predominated circulation in Puerto Rico from September to December 2020 and subsequently spread to the United States. The results of this collaborative approach highlight the importance of timely collection and analysis of SARS-CoV-2 genomic surveillance data to inform public health responses.

We reconstructed the SARS-CoV-2 epidemic caused by Omicron variant in Puerto Rico by sampling genomes collected during October 2021-May 2022. Our study revealed that Omicron BA.1 emerged and replaced Delta as the predominant variant in December 2021. Increased transmission rates and a dynamic landscape of Omicron sublineage infections followed.

In May 2019, the Food and Drug Administration issued approval for Dengvaxia (Sanofi Pasteur), a live-attenuated, chimeric tetravalent dengue vaccine (1). In June 2021, the Advisory Committee on Immunization Practices (ACIP) recommended vaccination with Dengvaxia for children and adolescents aged 9–16 years with laboratory confirmation of previous dengue virus infection and who live in areas with endemic dengue transmission, such as the U.S. Virgin Islands (USVI)† (2). Confirming previous dengue virus infection before vaccine administration (prevaccination screening) is important because 1) although Dengvaxia decreases hospitalization and severe disease from dengue among persons with a previous infection, it increases the risk for these outcomes among persons without a previous infection; 2) many dengue virus infections are asymptomatic; and 3) many patients with symptomatic infections do not seek medical attention or receive appropriate testing (3). Sufficient laboratory evidence of previous dengue virus infection includes a history of laboratory-confirmed dengue§ or a positive serologic test result that meets ACIP-recommended performance standards for prevaccination screening, defined as high specificity (≥98%) and sensitivity (≥75%). A seroprevalence of 20% in the vaccine-eligible population (corresponding to a positive predictive value of ≥90% for a test with minimum sensitivity of 75% and minimum specificity of 98%) is recommended to maximize vaccine safety and minimize the risk for vaccinating persons without a previous dengue virus infection (2).

Dengue and influenza are pathogens of global concern and cause febrile illness similar to COVID-19. We analyzed data from an enhanced surveillance system operating from three emergency departments and an urgent care clinic in Puerto Rico to identify clinical features predictive of influenza or dengue compared with COVID-19. Participants with fever or respiratory symptoms and aged 18 years enrolled May 2012-January 2021 with dengue, influenza, or SARS-CoV-2 confirmed by reverse transcriptase polymerase chain reaction were included. We calculated adjusted odds ratios (aORs) and 95% CIs using logistic regression to assess clinical characteristics of participants with COVID-19 compared to those with dengue or influenza, adjusting for age, subregion, and days from illness onset to presentation for clinical care. Among 13,431 participants, we identified 2,643 with dengue (N = 303), influenza (N = 2,064), or COVID-19 (N = 276). We found differences in days from onset to presentation among influenza (2 days [interquartile range: 1-3]), dengue (3 days [2-4]), and COVID-19 cases (4 days [2-7]; P < 0.001). Cough (aOR: 0.12 [95% CI: 0.07-0.19]) and shortness of breath (0.18 [0.08-0.44]) were less common in dengue compared with COVID-19. Facial flushing (20.6 [9.8-43.5]) and thrombocytopenia (24.4 [13.3-45.0]) were more common in dengue. Runny nose was more common in influenza compared with COVID-19 (8.3 [5.8-12.1]). In summary, cough, shortness of breath, facial flushing, and thrombocytopenia helped distinguish between dengue and COVID-19. Although few features distinguished influenza from COVID-19, presentation > 4 days after symptom onset suggests COVID-19. These findings may assist clinicians making time-sensitive decisions regarding triage, isolation, and management while awaiting pathogen-specific testing.

BACKGROUND: Puerto Rico has experienced the full impact of the COVID-19 pandemic. Since SARS-CoV-2, the virus that causes COVID-19, was first detected on the island in March of 2020, it spread rapidly though the island's population and became a critical threat to public health. METHODS: We conducted a genomic surveillance study through a partnership with health agencies and academic institutions to understand the emergence and molecular epidemiology of the virus on the island. We sampled COVID-19 cases monthly over 19 months and sequenced a total of 753 SARS-CoV-2 genomes between March 2020 and September 2021 to reconstruct the local epidemic in a regional context using phylogenetic inference. RESULTS: Our analyses reveal that multiple importation events propelled the emergence and spread of the virus throughout the study period, including the introduction and spread of most SARS-CoV-2 variants detected world-wide. Lineage turnover cycles through various phases of the local epidemic were observed, where the predominant lineage was replaced by the next competing lineage or variant after ~4 months of circulation locally. We also identified the emergence of lineage B.1.588, an autochthonous lineage that predominated in Puerto Rico from September to December 2020 and subsequently spread to the United States. CONCLUSIONS: The results of this collaborative approach highlight the importance of timely collection and analysis of SARS-CoV-2 genomic surveillance data to inform public health responses.

Dengue is the disease caused by 1 of 3 distinct, but closely related dengue viruses (DENV-1-4) that are transmitted by Aedes spp. mosquito vectors. It is the most common arboviral disease worldwide, with the greatest burden in tropical and sub-tropical regions. In the absence of effective prevention and control measures, dengue is projected to increase in both disease burden and geographic range. Given its increasing importance as an etiology of fever in the returning traveler or the possibility of local transmission in regions in the United States with competent vectors, as well as the risk for large outbreaks in endemic US territories and associated states, clinicians should understand its clinical presentation and be familiar with appropriate testing, triage, and management of patients with dengue. Control and prevention efforts reached a milestone in June 2021 when the Advisory Committee on Immunization Practices (ACIP) recommended Dengvaxia for routine use in children aged 9 to 16 years living in endemic areas with laboratory confirmation of previous dengue virus infection. Dengvaxia is the first vaccine against dengue to be recommended for use in the United States and one of the first to require laboratory testing of potential recipients to be eligible for vaccination. In this review, we outline dengue pathogenesis, epidemiology, and key clinical features for front-line clinicians evaluating patients presenting with dengue. We also provide a summary of Dengvaxia efficacy, safety, and considerations for use as well as an overview of other potential new tools to control and prevent the growing threat of dengue .

Hispanics are the majority ethnic population in Puerto Rico where we reviewed charts of 109 hospitalized COVID-19 patients to better understand demographic and clinical characteristics of COVID-19 and determine risk factors for poor outcomes. Eligible medical records of hospitalized patients with confirmed COVID-19 illnesses were reviewed at four participating hospitals in population centers across Puerto Rico and data were abstracted that described the clinical course, interventions, and outcomes. We found hospitalized patients had a median of 3 underlying conditions with obesity and diabetes as the most frequently reported conditions. Intensive care unit (ICU) admission occurred among 28% of patients and 18% of patients died during the hospitalization. Patients 65 or older or with immune deficiencies had a higher risk for death. Common symptoms included cough, dyspnea, and fatigue; less than half of patients in the study reported fever which was less frequent than reported elsewhere in the literature. It is important for interventions within Hispanic communities to protect high-risk groups.

BACKGROUND: Despite achievements in the reduction of malaria globally, imported malaria cases to the United States by returning international travelers continue to increase. Immigrants to the United States from sub-Saharan Africa (SSA) who then travel back to their homelands to visit friends and relatives (VFRs) experience a disproportionate burden of malaria illness. Various studies have explored barriers to malaria prevention among VFRs and non-VFRs-travelers to the same destinations with other purpose for travel-but few employed robust epidemiologic study designs or performed comparative analyses of these two groups. To better quantify the key barriers that VFRs face to implement effective malaria prevention measures, we conducted a comprehensive community-based, cross-sectional, survey to identify differences in malaria prevention knowledge, attitudes, and practices (KAP) among VFRs and others traveling to Africa and describe the differences between VFRs and other types of international travelers. METHODS AND FINDINGS: Three distinct populations of travelers with past or planned travel to malaria-endemic countries of SSA were surveyed: VFRs diagnosed with malaria as reported through a state health department; members of the general VFR population (community); and VFR and non-VFR travelers presenting to a travel health clinic, both before their pretravel consultation and again, after return from travel. A Community Advisory Board of African immigrants and prior qualitative research informed survey development and dissemination. Across the three groups, 489 travelers completed surveys: 351 VFRs and 138 non-VFRs. VFRs who reported taking antimalarials on their last trip rated their concern about malaria higher than those who did not. Having taken five or more trips to SSA was reported more commonly among VFRs diagnosed with malaria than community VFRs (44.0% versus 20.4%; p = 0.008). Among travel health clinic patients surveyed before and after travel, VFR travelers were less successful than non-VFRs in adhering to their planned use of antimalarials (82.2% versus 98.7%; p = 0.001) and employing mosquito bite avoidance techniques (e.g., using bed nets: 56.8% versus 81.8%; p = 0.009). VFRs who visited the travel health clinic were more likely than VFR respondents from the community to report taking an antimalarial (83.0% versus 61.9%; p = 0.009), or to report bite avoidance behaviors (e.g., staying indoors when mosquitoes were out: 80.9% versus 59.5%; p = 0.009). CONCLUSIONS: We observed heterogeneity in malaria prevention behaviors among VFRs and between VFR and non-VFR traveler populations. Although VFRs attending the travel health clinic appear to demonstrate better adherence to malaria prevention measures than VFR counterparts surveyed in the community, specialized pretravel care is not sufficient to ensure chemoprophylaxis use and bite avoidance behaviors among VFRs. Even when seeking specialized pretravel care, VFRs experience greater barriers to the use of malaria prevention than non-VFRs. Addressing access to health care and upstream barrier reduction strategies that make intended prevention more achievable, affordable, easier, and resonant among VFRs may improve malaria prevention intervention effectiveness.

BACKGROUND: Over half of malaria cases reported in the United States occur among people traveling to visit friends and relatives (VFRs), predominantly to West Africa. Few studies have queried VFR travelers directly on barriers to seeking pre-travel care. We aim to describe the knowledge, attitudes, and practices of VFRs traveling to malaria-endemic countries from the United States. With these findings, we aim to design interventions to encourage preventive behaviors before and during travel. METHODS: Sixteen focus groups were held in two US metropolitan areas with West African immigrant populations: Minneapolis-St. Paul, MN, and New York City, NY. A total of 172 people from 13 African countries participated. Focus group discussions were audio-recorded and transcribed, and modified grounded theory analysis was performed. Participants reviewed themes to verify intent of statements. RESULTS: Participants described the high cost of provider visits and chemoprophylaxis, challenges in advocating for themselves in healthcare settings, and concerns about offending or inconveniencing hosts as barriers to malaria prevention. Cultural barriers to accessing pre-travel care included competing priorities when trip planning, such as purchasing gifts for family, travel logistics, and safety concerns. When participants sought pre-travel care, most consulted their primary care provider. Participants expressed low confidence in US providers' knowledge and training about malaria and other tropical diseases. CONCLUSION: Barriers to pre-travel care for VFR travelers are multifaceted and extend beyond their perception of disease risk. Only some barriers previously reported in anecdotal and qualitative literature were supported in our findings. Future interventions should be aimed at barriers identified by individual communities and involve primary and travel specialist healthcare providers. Additional work is needed to address systems-level barriers to accessing care and establishing community-based programs to support West African VFR traveler health.

The use of participatory approaches involving community stakeholders is novel in travel medicine research. We describe various community-based participatory methods, using the examples of community advisory boards (CABs), community-based organisations (CBOs), and focus groups as mechanisms for achieving a desired interventional outcome. While these methodologies can be applied to many settings, we used them to investigate barriers to malaria prevention in travellers visiting friends and relatives (VFRs) and to implement interventions targeting VFRs.