Investigating SARS-CoV-2 Incidence and Morbidity in Ponce, Puerto Rico: Protocol and Baseline Results From a Community Cohort Study.

BACKGROUND: A better understanding of SARS-CoV-2 infection risk among Hispanic and Latino populations and in low-resource settings in the United States is needed to inform control efforts and strategies to improve health equity. Puerto Rico has a high poverty rate and other population characteristics associated with increased vulnerability to COVID-19, and there are limited data to date to determine community incidence. OBJECTIVE: This study describes the protocol and baseline seroprevalence of SARS-CoV-2 in a prospective community-based cohort study (COPA COVID-19 [COCOVID] study) to investigate SARS-CoV-2 infection incidence and morbidity in Ponce, Puerto Rico. METHODS: In June 2020, we implemented the COCOVID study within the Communities Organized to Prevent Arboviruses project platform among residents of 15 communities in Ponce, Puerto Rico, aged 1 year or older. Weekly, participants answered questionnaires on acute symptoms and preventive behaviors and provided anterior nasal swab samples for SARS-CoV-2 polymerase chain reaction testing; additional anterior nasal swabs were collected for expedited polymerase chain reaction testing from participants that reported 1 or more COVID-19-like symptoms. At enrollment and every 6 months during follow-up, participants answered more comprehensive questionnaires and provided venous blood samples for multiantigen SARS-CoV-2 immunoglobulin G antibody testing (an indicator of seroprevalence). Weekly follow-up activities concluded in April 2022 and 6-month follow-up visits concluded in August 2022. Primary study outcome measures include SARS-CoV-2 infection incidence and seroprevalence, relative risk of SARS-CoV-2 infection by participant characteristics, SARS-CoV-2 household attack rate, and COVID-19 illness characteristics and outcomes. In this study, we describe the characteristics of COCOVID participants overall and by SARS-CoV-2 seroprevalence status at baseline. RESULTS: We enrolled a total of 1030 participants from 388 households. Relative to the general populations of Ponce and Puerto Rico, our cohort overrepresented middle-income households, employed and middle-aged adults, and older children (P<.001). Almost all participants (1021/1025, 99.61%) identified as Latino/a, 17.07% (175/1025) had annual household incomes less than US $10,000, and 45.66% (463/1014) reported 1 or more chronic medical conditions. Baseline SARS-CoV-2 seroprevalence was low (16/1030, 1.55%) overall and increased significantly with later study enrollment time (P=.003). CONCLUSIONS: The COCOVID study will provide a valuable opportunity to better estimate the burden of SARS-CoV-2 and associated risk factors in a primarily Hispanic or Latino population, assess the limitations of surveillance, and inform mitigation measures in Puerto Rico and other similar populations. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/53837.

Quantifying the relationship between arboviral infection prevalence and human mobility patterns among participants of the Communities Organized to Prevent Arboviruses cohort (COPA) in southern Puerto Rico.

Human movement is increasingly being recognized as a major driver of arbovirus risk and dissemination. The Communities Organized to Prevent Arboviruses (COPA) study is a cohort in southern Puerto Rico to measure arboviral prevalence, evaluate interventions, and collect mobility data. To quantify the relationship between arboviral prevalence and human mobility patterns, we fit multilevel logistic regression models to estimate odds ratios for mobility-related predictors of positive chikungunya IgG or Zika IgM test results collected from COPA, assuming mobility data does not change substantially from year to year. From May 8, 2018-June 8, 2019, 39% of the 1,845 active participants during the study period had a positive arboviral seroprevalence result. Most (74%) participants reported spending five or more weekly hours outside of their home. A 1% increase in weekly hours spent outside the home was associated with a 4% (95% confidence interval (CI): 2-7%) decrease in the odds of testing positive for arbovirus. After adjusting for age and whether a person had air conditioning (AC) at home, any time spent in a work location was protective against arbovirus infection (32% decrease, CI: 9-49%). In fact, there was a general decreased prevalence for individuals who visited locations that were inside and had AC or screens, regardless of the type of location (32% decrease, CI: 12-47%). In this population, the protective characteristics of locations visited appear to be the most important driver of the relationship between mobility and arboviral prevalence. This relationship indicates that not all mobility is the same, with elements like screens and AC providing protection in some locations. These findings highlight the general importance of AC and screens, which are known to be protective against mosquitoes and mosquito-transmitted diseases.

Travel-Associated Dengue Cases - United States, 2010-2021.

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.

Travel-Associated Dengue Cases - United States, 2010-2021.

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.

Previous Dengue Infection among Children in Puerto Rico and Implications for Dengue Vaccine Implementation.

Limited dengue virus (DENV) seroprevalence estimates are available for Puerto Rico, which are needed to inform the potential use and cost-effectiveness of DENV vaccines. The Communities Organized to Prevent Arboviruses (COPA) is a cohort study initiated in 2018 in Ponce, Puerto Rico, to assess arboviral disease risk and provide a platform to evaluate interventions. We recruited participants from households in 38 study clusters, who were interviewed and provided a serum specimen. Specimens from 713 children aged 1 to 16 years during the first year of COPA were tested for the four DENV serotypes and ZIKV using a focus reduction neutralization assay. We assessed the seroprevalence of DENV and ZIKV by age and developed a catalytic model from seroprevalence and dengue surveillance data to estimate the force of infection for DENV during 2003-2018. Overall, 37% (n = 267) were seropositive for DENV; seroprevalence was 9% (11/128) among children aged 1 to 8 years and 44% (256/585) among children aged 9 to 16 years, exceeding the threshold over which DENV vaccination is deemed cost-effective. A total of 33% were seropositive for ZIKV, including 15% among children aged 0 to 8 years and 37% among children aged 9 to 16 years. The highest force of infection occurred in 2007, 2010, and 2012-2013, with low levels of transmission from 2016 to 2018. A higher proportion of children had evidence of multitypic DENV infection than expected, suggesting high heterogeneity in DENV risk in this setting.

Dengue vaccine acceptability before and after the availability of COVID-19 vaccines in Puerto Rico.

Dengue is a growing public health threat, causing approximately 400 million infections annually. In June 2021, the Advisory Committee on Immunization Practices recommended the first dengue vaccine (CYD-TDV) for children aged 9-16 years with a previous dengue infection, living in endemic areas, such as Puerto Rico (PR). As the COVID-19 pandemic affected vaccine intention worldwide, we assessed dengue vaccine intention before (pre-COVID) and after (post-COVID) COVID-19 vaccine availability among participants enrolled in the Communities Organized to Prevent Arboviruses (COPA) cohort to prepare for dengue vaccine implementation in PR. We used logistic regression models to evaluate changes in dengue vaccine intention by interview timing and participant characteristics. Among 2,513 participants pre-COVID, 2,512 answered the dengue vaccine intention question for themselves, and 1,564 answered relative to their children. Post-COVID, dengue vaccine intention in adults increased for themselves from 73.4% to 84.5% (adjusted odds ratio (aOR) = 2.27, 95%CI: 1.90-2.71) and relative to their children from 75.6% to 85.5% (aOR = 2.21, 95%CI: 1.75-2.78). Among all participants, groups with higher dengue vaccine intention included those who reported previous year influenza vaccine uptake and those who reported being frequently bitten by mosquitos, compared to those who did not. Adult males were also more likely to intend to vaccinate themselves than females. Respondents who were employed or in school were less likely to intend to vaccinate compared to those who were not working. The primary reasons for vaccine hesitancy were concerns with side effects and not believing in vaccines, which should be considered during educational strategies prior to dengue vaccine implementation. In general, dengue vaccine intention is high in PR and has increased after COVID-19 vaccine availability, potentially due to increased awareness of vaccine importance during the COVID-19 pandemic.

Epidemiologic Trends of Dengue in U.S. Territories, 2010-2020.

Problem/Condition: Dengue is one of the most common vectorborne flaviviral infections globally, with frequent outbreaks in tropical regions. In 2019 and 2020, the Pan American Health Organization reported approximately 5.5 million dengue cases from the Americas, the highest number on record. In the United States, local dengue virus (DENV) transmission has been reported from all U.S. territories, which are characterized by tropical climates that are highly suitable for Aedes species of mosquitoes, the vector that transmits dengue. Dengue is endemic in the U.S. territories of American Samoa, Puerto Rico, and the U.S. Virgin Islands (USVI). Dengue risk in Guam and the Commonwealth of the Northern Mariana Islands is considered sporadic or uncertain. Despite all U.S. territories reporting local dengue transmission, epidemiologic trends over time have not been well described. Reporting Period: 2010-2020. Description of System: State and territorial health departments report dengue cases to CDC through ArboNET, the national arboviral surveillance system, which was developed in 2000 to monitor West Nile virus infections. Dengue became nationally notifiable in ArboNET in 2010. Dengue cases reported to ArboNET are categorized using the 2015 Council of State and Territorial Epidemiologists case definition. In addition, DENV serotyping is performed at CDC's Dengue Branch Laboratory in a subset of specimens to support identification of circulating DENV serotypes. Results: During 2010-2020, a total of 30,903 dengue cases were reported from four U.S. territories to ArboNET. Puerto Rico reported the highest number of dengue cases (29,862 [96.6%]), followed by American Samoa (660 [2.1%]), USVI (353 [1.1%]), and Guam (28 [0.1%]). However, annual incidence rates were highest in American Samoa with 10.2 cases per 1,000 population in 2017, followed by Puerto Rico with 2.9 in 2010 and USVI with 1.6 in 2013. Approximately one half (50.6%) of cases occurred among persons aged <20 years. The proportion of persons with dengue who were hospitalized was high in three of the four territories: 45.5% in American Samoa, 32.6% in Puerto Rico, and 32.1% in Guam. In Puerto Rico and USVI, approximately 2% of reported cases were categorized as severe dengue. Of all dengue-associated deaths, 68 (0.2%) were reported from Puerto Rico; no deaths were reported from the other territories. During 2010-2020, DENV-1 and DENV-4 were the predominant serotypes in Puerto Rico and USVI. Interpretation: U.S. territories experienced a high prevalence of dengue during 2010-2020, with approximately 30,000 cases reported, and a high incidence during outbreak years. Children and adolescents aged <20 years were disproportionately affected, highlighting the need for interventions tailored for this population. Ongoing education about dengue clinical management for health care providers in U.S. territories is important because of the high hospitalization rates reported. Dengue case surveillance and serotyping can be used to guide future control and prevention measures in these areas. Public Health Action: The Advisory Committee on Immunization Practices recommends vaccination with Dengvaxia for children aged 9-16 years with evidence of previous dengue infection and living in areas where dengue is endemic. The recommendation for the dengue vaccine offers public health professionals and health care providers a new intervention for preventing illness and hospitalization in the age group with the highest burden of disease in the four territories (Paz Bailey G, Adams L, Wong JM, et al. Dengue Vaccine: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021. MMWR Recomm Rep 2021;70[No. RR-6]). American Samoa, Puerto Rico, and USVI are all considered endemic areas and persons residing in these areas are eligible for the new dengue vaccine. Persons aged 9-16 years in those jurisdictions with laboratory evidence of previous dengue infection can receive the dengue vaccine and benefit from a reduced risk for symptomatic disease, hospitalization, or severe dengue. Health care providers in these areas should be familiar with the eligibility criteria and recommendations for vaccination to reduce the burden of dengue among the group at highest risk for symptomatic illness. Educating health care providers about identification and management of dengue cases can improve patient outcomes and improve surveillance and reporting of dengue cases.

Arbovirus risk perception as a predictor of mosquito-bite preventive behaviors in Ponce, Puerto Rico.

Mosquito-borne arboviruses are an important cause of morbidity and mortality in the Caribbean. In Puerto Rico, chikungunya, dengue, and Zika viruses have each caused large outbreaks during 2010-2022. To date, the majority of control measures to prevent these diseases focus on mosquito control and many require community participation. In 2018, the U.S. Centers for Disease Control and Prevention launched the COPA project, a community-based cohort study in Ponce, Puerto Rico, to measure the impact of novel vector control interventions in reducing arboviral infections. Randomly selected households from 38 designated cluster areas were offered participation, and baseline data were collected from 2,353 households between May 2018 and May 2019. Household-level responses were provided by one representative per home. Cross-sectional analyses of baseline data were conducted to estimate 1) the association between arboviral risk perception and annual household expenditure on mosquito control, and 2) the association between arboviral risk perception and engagement in ≥3 household-level risk reduction behaviors. In this study, 27% of household representatives believed their household was at high risk of arboviruses and 36% of households engaged in at least three of the six household-level preventive behaviors. Households where the representative perceived their household at high risk spent an average of $35.9 (95% confidence interval: $23.7, $48.1) more annually on mosquito bite prevention compared to households where the representative perceived no risk. The probability of engaging in ≥3 household-level mosquito-preventive behaviors was 10.2 percentage points greater (7.2, 13.0) in households where the representatives perceived high risk compared to those in which the representatives perceived no risk. Paired with other research, these results support investment in community-based participatory approaches to mosquito control and providing accessible information for communities to accurately interpret their risk.

COVID-19 Vaccination Intention in a Community Cohort in Ponce, Puerto Rico.

As of January 20, 2022, > 247,000 confirmed COVID-19 cases and 3,600 deaths were reported in Puerto Rico (PR). We interviewed participants aged ≥ 14 years in the Communities Organized to Prevent Arboviruses (COPA) study, a community-based cohort in PR, about COVID-19 vaccine intention from November 12, 2020, to June 25, 2021. We used univariate and adjusted analyses to identify participant characteristics associated with vaccine intention. Among 1,542 respondents, the median age was 37 years (interquartile range 23-45) and 914 (59%) were female. Most participants (83%) reported a willingness to receive a COVID-19 vaccine. The most common reason for vaccine hesitancy was concern about the safety or side effects (64%). Willingness to receive the COVID-19 vaccine was associated with a later interview date, higher household income, previous COVID-19 diagnosis among household members, COVID-19 risk perception, influenza vaccine uptake, dengue vaccine intention, and general positive perceptions of vaccines. While parents with minors (< 21 years old) were less likely to report vaccine intention for themselves than participants without minor children, we observed similar characteristics associated with parents' willingness to vaccinate their children. Overall, COVID-19 vaccine intention was high among COPA participants. It is important that public health messaging in PR addresses COVID-19 vaccine safety and possible side effects.

Risk factors for infection with chikungunya and Zika viruses in southern Puerto Rico: A community-based cross-sectional seroprevalence survey.

Chikungunya virus (CHIKV) caused a large outbreak in Puerto Rico in 2014, followed by a Zika virus (ZIKV) outbreak in 2016. Communities Organized for the Prevention of Arboviruses (COPA) is a cohort study in southern Puerto Rico, initiated in 2018 to measure arboviral disease risk and provide a platform to evaluate interventions. To identify risk factors for infection, we assessed prevalence of previous CHIKV infection and recent ZIKV and DENV infection in a cross-sectional study among COPA participants. Participants aged 1-50 years (y) were recruited from randomly selected households in study clusters. Each participant completed an interview and provided a blood specimen, which was tested by anti-CHIKV IgG ELISA assay and anti-ZIKV and anti-DENV IgM MAC-ELISA assays. We assessed individual, household, and community factors associated with a positive result for CHIKV or ZIKV after adjusting for confounders. During 2018-2019, 4,090 participants were enrolled; 61% were female and median age was 28y (interquartile range [IQR]: 16-41). Among 4,035 participants tested for CHIKV, 1,268 (31.4%) had evidence of previous infection. CHIKV infection prevalence was lower among children 1-10 years old compared to people 11 and older (adjusted odds ratio [aOR] 2.30; 95% CI 1.71-3.08). Lower CHIKV infection prevalence was associated with home screens (aOR 0.51; 95% CI 0.42-0.61) and air conditioning (aOR 0.64; 95% CI 0.54-0.77). CHIKV infection prevalence also varied by study cluster of residence and insurance type. Few participants (16; 0.4%) had evidence of recent DENV infection by IgM. Among 4,035 participants tested for ZIKV, 651 (16%) had evidence of recent infection. Infection prevalence increased with older age, from 7% among 1-10y olds up to 19% among 41-50y olds (aOR 3.23; 95% CI 2.16-4.84). Males had an increased risk of Zika infection prevalence compared with females (aOR 1.31; 95% CI 1.09-1.57). ZIKV infection prevalence also decreased with the presence of home screens (aOR 0.66; 95% CI 0.54-0.82) and air conditioning (aOR 0.69; 95% CI 0.57-0.84). Similar infection patterns were observed for recent ZIKV infection prevalence and previous CHIKV infection prevalence by age, and the presence of screens and air conditioners in the home decreased infection risk from both viruses by as much as 50%.

Risk Estimation of Sexual Transmission of Zika Virus-United States, 2016-2017.

BACKGROUND: Zika virus (ZIKV) can be transmitted sexually but the risk of sexual transmission remains unknown. Most evidence of sexual transmission is from partners of infected travelers returning from areas with ZIKV circulation. METHODS: We used data from the US national arboviral disease surveillance system on travel- and sexually acquired ZIKV disease cases during 2016-2017 to develop individual-level simulations for estimating risk of male-to-female, male-to-male, and female-to-male sexual transmission of ZIKV via vaginal and/or anal intercourse. We specified parametric distributions to characterize individual-level variability of parameters for ZIKV persistence and sexual behaviors. RESULTS: Using ZIKV RNA persistence in semen/vaginal fluids to approximate infectiousness duration, male-to-male transmission had the highest estimated probability (1.3% [95% confidence interval, CI, .4%-6.0%] per anal sex act), followed by male-to-female and female-to-male transmission (0.4% [95% CI, .3%-.6%] per vaginal/anal sex act and 0.1% [95% CI, 0%-.8%] per vaginal sex act, respectively). Models using viral isolation in semen vs RNA detection to approximate infectiousness duration predicted greater risk of sexual transmission. CONCLUSIONS: While likely insufficient to maintain sustained transmission, the estimated risk of ZIKV transmission through unprotected sex is not trivial and is especially important for pregnant women, as ZIKV infection can cause severe congenital disorders.

Estimating incidence of infection from diverse data sources: Zika virus in Puerto Rico, 2016.

Emerging epidemics are challenging to track. Only a subset of cases is recognized and reported, as seen with the Zika virus (ZIKV) epidemic where large proportions of infection were asymptomatic. However, multiple imperfect indicators of infection provide an opportunity to estimate the underlying incidence of infection. We developed a modeling approach that integrates a generic Time-series Susceptible-Infected-Recovered epidemic model with assumptions about reporting biases in a Bayesian framework and applied it to the 2016 Zika epidemic in Puerto Rico using three indicators: suspected arboviral cases, suspected Zika-associated Guillain-Barré Syndrome cases, and blood bank data. Using this combination of surveillance data, we estimated the peak of the epidemic occurred during the week of August 15, 2016 (the 33rd week of year), and 120 to 140 (50% credible interval [CrI], 95% CrI: 97 to 170) weekly infections per 10,000 population occurred at the peak. By the end of 2016, we estimated that approximately 890,000 (95% CrI: 660,000 to 1,100,000) individuals were infected in 2016 (26%, 95% CrI: 19% to 33%, of the population infected). Utilizing multiple indicators offers the opportunity for real-time and retrospective situational awareness to support epidemic preparedness and response.

HTrack: A new tool to facilitate public health field visits and electronic data capture.

Many applications have been developed for electronic data collection. However, offline field navigation tools incorporating secure electronic data capture and field visit tracking are currently scarce. We created an R-Shiny application, HTrack (Household Tracking), for use on encrypted Android devices in the field. The application was implemented in the Communities Organized to Prevent Arboviruses (COPA) project, a study beginning in 2018 to better understand arboviral disease incidence in 38 communities in Puerto Rico. The application was used to navigate to randomly selected structures and capture visit outcomes after conducting multiple visits for participant recruitment. It also served as a bridge to an alternate software, Epi Info, to collect participant-level questionnaire data. This application successfully captured each visit outcome and improved the logistics of field level activities for the COPA project, eliminating the use of paper maps for navigation. We show the development of HTrack and comment on the limitations and strengths of this application and further improvements.

Persistent Zika Virus Infection Associated with Early Fetal Demise: A Case Report.

BACKGROUND: Infection with Zika virus (ZIKV) during pregnancy is known to cause birth defects and could also be linked to pregnancy loss. CASE: A pregnant woman in Puerto Rico contracted ZIKV at 16 weeks gestation. ZIKV RNA persisted in serum from her initial test at 16 weeks through 24 weeks gestation, when fetal demise occurred, and was detected in placental tissue. CONCLUSION: Prolonged detection of ZIKV RNA in maternal serum was associated with ZIKV RNA detection in the placenta of a patient who experienced fetal demise. While detection of placenta ZIKV RNA does not establish that ZIKV conclusively caused the demise, these findings support emerging evidence that the placenta may serve as a reservoir for ZIKV, which may be associated with prolonged detection of ZIKV RNA in serum.

Colonization history and population differentiation of the Honey Bees (Apis mellifera L.) in Puerto Rico.

Honey bees (Apis mellifera L.) are the primary commercial pollinators across the world. The subspecies A. m. scutellata originated in Africa and was introduced to the Americas in 1956. For the last 60 years, it hybridized successfully with European subspecies, previous residents in the area. The result of this hybridization was called Africanized honey bee (AHB). AHB has spread since then, arriving to Puerto Rico (PR) in 1994. The honey bee population on the island acquired a mosaic of features from AHB or the European honey bee (EHB). AHB in Puerto Rico shows a major distinctive characteristic, docile behavior, and is called gentle Africanized honey bees (gAHB). We used 917 SNPs to examine the population structure, genetic differentiation, origin, and history of range expansion and colonization of gAHB in PR. We compared gAHB to populations that span the current distribution of A. mellifera worldwide. The gAHB population is shown to be a single population that differs genetically from the examined populations of AHB. Texas and PR groups are the closest genetically. Our results support the hypothesis that the Texas AHB population is the source of gAHB in Puerto Rico.

Molecular evolution of dengue 2 virus in Puerto Rico: positive selection in the viral envelope accompanies clade reintroduction.

Dengue virus is a circumtropical, mosquito-borne flavivirus that infects 50-100 million people each year and is expanding in both range and prevalence. Of the four co-circulating viral serotypes (DENV-1 to DENV-4) that cause mild to severe febrile disease, DENV-2 has been implicated in the onset of dengue haemorrhagic fever (DHF) in the Americas in the early 1980s. To identify patterns of genetic change since DENV-2's reintroduction into the region, molecular evolution in DENV-2 from Puerto Rico (PR) and surrounding countries was examined over a 20 year period of fluctuating disease incidence. Structural genes (over 20 % of the viral genome), which affect viral packaging, host-cell entry and immune response, were sequenced for 91 DENV-2 isolates derived from both low- and high-prevalence years. Phylogenetic analyses indicated that DENV-2 outbreaks in PR have been caused by viruses assigned to subtype IIIb, originally from Asia. Variation amongst DENV-2 viruses in PR has since largely arisen in situ, except for a lineage-replacement event in 1994 that appears to have non-PR New World origins. Although most structural genes have remained relatively conserved since the 1980s, strong evidence was found for positive selection acting on a number of amino acid sites in the envelope gene, which have also been important in defining phylogenetic structure. Some of these changes are exhibited by the multiple lineages present in 1994, during the largest Puerto Rican outbreak of dengue, suggesting that they may have altered disease dynamics, although their functional significance will require further investigation.

Fractura de húmero en el recién nacido. Presentación de un caso / Humerous fracture in the newborn. Case report

La fractura de húmero en el recién nacido es infrecuente, siendo raramente mencionada en la literatura. En este informe se trata de un recién nacido normal, que nació de parto eutósico y que producto de una maniobra intempestiva realizada por el personal que asistió el trabajo de parto en el “Hospital Comunitario de Augustinopolis”, Estado de Tocantins, Brasil, presentaba irritación y llanto siempre que era movilizado; por lo que es interconsultado con el Especialista en Ortopedia y Traumatología, el cual al realizarle examen físico minucioso, encontró que el cuadro clínico se exacerbaba siempre que era explorado el miembro superior derecho, por lo que decide ordenar se realice un Rx, constatándose fractura diafisaria de húmero, la cual es inmovilizada con férula posterior de yeso por 15 días teniendo una evolución satisfactoria. (AU)

Selection-driven evolution of emergent dengue virus.

In the last four decades the incidence of dengue fever has increased 30-fold worldwide, and over half the world's population is now threatened with infection from one or more of four co-circulating viral serotypes (DEN-1 through DEN-4). To determine the role of viral molecular evolution in emergent disease dynamics, we sequenced 40% of the genome of 82 DEN-4 isolates collected from Puerto Rico over the 20 years since the onset of endemic dengue on the island. Isolates were derived from years with varying levels of DEN-4 prevalence. Over our sampling period there were marked evolutionary shifts in DEN-4 viral populations circulating in Puerto Rico; viral lineages were temporally clustered and the most common genotype at a particular sampling time often arose from a previously rare lineage. Expressed changes in structural genes did not appear to drive this lineage turnover, even though these regions include primary determinants of viral antigenic properties. Instead, recent dengue evolution can be attributed in part to positive selection on the nonstructural gene 2A (NS2A), whose functions may include replication efficiency and antigenicity. During the latest and most severe DEN-4 epidemic in Puerto Rico, in 1998, viruses were distinguished by three amino acid changes in NS2A that were fixed far faster than expected by drift alone. Our study therefore demonstrates viral genetic turnover within a focal population and the potential importance of adaptive evolution in viral epidemic expansion.