Genetic ancestry, admixture, and population structure in rural Dominica.

The Caribbean is a genetically diverse region with heterogeneous admixture compositions influenced by local island ecologies, migrations, colonial conflicts, and demographic histories. The Commonwealth of Dominica is a mountainous island in the Lesser Antilles historically known to harbor communities with unique patterns of migration, mixture, and isolation. This community-based population genetic study adds biological evidence to inform post-colonial narrative histories in a Dominican horticultural village. High density single nucleotide polymorphism data paired with a previously compiled genealogy provide the first genome-wide insights on genetic ancestry and population structure in Dominica. We assessed family-based clustering, inferred global ancestry, and dated recent admixture by implementing the fastSTRUCTURE clustering algorithm, modeling graph-based migration with TreeMix, assessing patterns of linkage disequilibrium decay with ALDER, and visualizing data from Dominica with Human Genome Diversity Panel references. These analyses distinguish family-based genetic structure from variation in African, European, and indigenous Amerindian admixture proportions, and analyses of linkage disequilibrium decay estimate admixture dates 5-6 generations (~160 years) ago. African ancestry accounts for the largest mixture components, followed by European and then indigenous components; however, our global ancestry inferences are consistent with previous mitochondrial, Y chromosome, and ancestry marker data from Dominica that show uniquely higher proportions of indigenous ancestry and lower proportions of African ancestry relative to known admixture in other French- and English-speaking Caribbean islands. Our genetic results support local narratives about the community's history and founding, which indicate that newly emancipated people settled in the steep, dense vegetation along Dominica's eastern coast in the mid-19th century. Strong genetic signals of post-colonial admixture and family-based structure highlight the localized impacts of colonial forces and island ecologies in this region, and more data from other groups are needed to more broadly inform on Dominica's complex history and present diversity.

An Assessment of Climate Change and Health Vulnerability and Adaptation in Dominica.

A climate change and health vulnerability and adaptation assessment was conducted in Dominica, a Caribbean small island developing state located in the Lesser Antilles. The assessment revealed that the country's population is already experiencing many impacts on health and health systems from climate variability and change. Infectious diseases as well as food and waterborne diseases pose continued threats as climate change may exacerbate the related health risks. Threats to food security were also identified, with particular concern for food production systems. The findings of the assessment included near-term and long-term adaptation options that can inform actions of health sector decision-makers in addressing health vulnerabilities and building resilience to climate change. Key challenges include the need for enhanced financial and human resources to build awareness of key health risks and increase adaptive capacity. Other small island developing states interested in pursuing a vulnerability and adaptation assessment may find this assessment approach, key findings, analysis, and lessons learned useful.

Outbreak of Zika Virus Infections, Dominica, 2016.

In February 2016, the World Health Organization declared the pandemic of Zika virus a public health emergency. On March 4, 2016, Dominica reported its first autochthonous Zika virus disease case; subsequently, 1,263 cases were reported. We describe the outbreak through November 2016, when the last known case was reported.

First reported enterovirus D68 infection in pediatric patients from the Caribbean region: evidence of spread from the U.S. outbreak / Primeros casos notificados en el Caribe de infección por enterovirus D68 en pacientes pediátricos: pruebas de la propagación del brote de los Estados Unidos

ABSTRACT The 2014 enterovirus D68 (EV-D68) outbreak in the United States raised concerns about the introduction of the virus in the Caribbean region. The objective of this study was to provide rapid evidence of the introduction of EV-D68 strains in the Caribbean region during the 2014 outbreak in the United States, using a relatively simple phylogenetic approach. From October 2014 to May 2015, four EV-D68 cases from two countries (Bermuda and Dominica) were detected at the regional referral laboratory at the Caribbean Public Health Agency (Port of Spain, Trinidad and Tobago) based on molecular testing of respiratory specimens. All cases were children presenting to hospitals with moderate respiratory distress. No cases of acute flaccid paralysis were detected. Phylogenetic analysis of the Caribbean strains showed more than 99% similarity with the 2014 U.S.-outbreak strain, providing evidence of the introduction and circulation of the virus in the region.(AU)

RESUMEN El brote de enterovirus D68 (EV-D68) registrado en el 2014 en los Estados Unidos suscitó preocupación acerca de la introducción del virus en el Caribe. El objetivo de este estudio fue aportar pruebas rápidas, mediante la adopción de un enfoque filogénico relativamente sencillo, de que durante ese brote ingresaron en el Caribe cepas del EV-D68. Entre octubre del 2014 y mayo del 2015, el laboratorio regional de referencia ubicado en el Organismo de Salud Pública del Caribe (Puerto España, Trinidad y Tabago) detectó cuatro casos de EV-D68 provenientes de dos países (Bermudas y Dominica) mediante el análisis molecular de muestras respiratorias. Todos los casos correspondían a niños que acudieron al hospital con dificultad respiratoria moderada. No se detectó ningún caso de parálisis flácida aguda. El análisis filogénico de las cepas encontradas en el Caribe demostró una semejanza superior al 99 % con la cepa responsable del brote del 2014 en los Estados Unidos, lo que demuestra la introducción y la circulación del virus en la región.(AU)

Spatial and Temporal Clustering of Chikungunya Virus Transmission in Dominica.

Using geo-referenced case data, we present spatial and spatio-temporal cluster analyses of the early spread of the 2013-2015 chikungunya virus (CHIKV) in Dominica, an island in the Caribbean. Spatial coordinates of the locations of the first 417 reported cases observed between December 15th, 2013 and March 11th, 2014, were captured using the Global Positioning System (GPS). We observed a preponderance of female cases, which has been reported for CHIKV outbreaks in other regions. We also noted statistically significant spatial and spatio-temporal clusters in highly populated areas and observed major clusters prior to implementation of intensive vector control programs suggesting early vector control measures, and education had an impact on the spread of the CHIKV epidemic in Dominica. A dynamical identification of clusters can lead to local assessment of risk and provide opportunities for targeted control efforts for nations experiencing CHIKV outbreaks.

Reptile-associated ticks from Dominica and the Bahamas with notes on hyperparasitic erythraeid mites.

Ticks were collected or recorded from 522 individual reptiles on Dominica and from 658 reptiles from the Bahamas. Two species of ticks were collected on Dominica: Amblyomma antillorum and Amblyomma rotundatum. Similarly, 2 species were collected in the Bahamas: Amblyomma albopictum and Amblyomma torrei. On Dominica, A. antillorum was recorded from 517 Lesser Antillean iguanas (Iguana delicatissima), 2 boa constrictors (Boa nebulosa), 1 Antilles snake (Alsophis sibonius), and 1 Dominican ground lizard (Ameiva fuscata), whereas A. rotundatum was recorded from 1 Lesser Antillean skink (Mabuya mabouya). In the Bahamas, A. albopictum was recorded from 131 Andros iguanas (Cyclura cychlura cychlura), 271 Exuma Island iguanas (Cyclura cychlura figginsi), and 1 Andros curlytail lizard (Leiocephalus carinatus coryi), whereas A. torrei was recorded from 255 Exuma Island iguanas. In the Bahamas, A. albopictum parasitized iguanas on Andros Island and the central Exuma Islands, and A. torrei parasitized iguanas in the southern Exumas. An exception to this trend was that A. torrei was collected from iguanas on Pasture Cay in the central Exumas, an anomaly that is explained by the fact that iguanas (with attached ticks) on Pasture Cay were introduced by humans in the past from islands further south. External hyperparasitic larval erythraeid mites ( Leptus sp.) were recorded from A. torrei in the Bahamas.

Distribution, burden, and impact of acute gastroenteritis in Dominica, 2009-2010.

Acute gastroenteritis (AGE) is an important public-health issue in Dominica. To determine the burden of AGE in Dominica, a retrospective, cross-sectional population survey was conducted in March-April 2009 and October 2010 (low- and-high-AGE seasons) and a laboratory survey from April 2009 to March 2010. The overall monthly prevalence of self-reported AGE was 8.6 % (95% CI 7.0-10.6); the incidence rate was 1.1 episodes/person-year and 79,157.1 episodes of AGE for the total population/year. Monthly prevalence of AGE was the highest in the 1-4 year(s) age-group (25.0%), higher in females (10.8%) and also varied by health district, with the highest monthly prevalence of AGE being reported in the Portsmouth district (13.1%). This difference in gender and across the health region was statistically significant. The estimated underreporting of syndromic AGE to the Ministry of Health was 83.3%. Furthermore, for every reported laboratory-confirmed case of AGE and foodbome disease (FBD), there was an estimated underreporting factor of 280. Overall, 47% of AGE specimens tested were positive for FBD pathogens. The predominant pathogens isolated were norovirus, followed by Giardia, Salmonella, and Shigella. The total annual estimated cost of AGE was US$ 1,371,852.92, and the total cost per capita due to AGE was US$ 19.06, indicating an economic burden of AGE-related illness on a small island of Dominica.

Phage-displayed antibody fragments recognizing dengue 3 and dengue 4 viruses as tools for viral serotyping in sera from infected individuals.

The current study shows the usefulness of dengue-3- and dengue-4-specific phage-displayed antibody fragments as tools for viral detection and serotyping in sera from infected individuals. C6/36 HT cells were inoculated with acute-phase sera from patients, and supernatants were collected daily and analyzed by ELISA using phage-displayed antibody fragments as serotype-specific detector reagents. Serotyping of most samples was possible as early as two to three days postinoculation. Results were comparable with those obtained by indirect immunofluorescence assay but were obtained in a shorter period of time (<1 week). Phage-displayed antibody fragments were better tools for diagnosis and serotyping than their soluble counterparts. Our approach combines the advantages of viral isolation and ELISA techniques. These results could be the basis for the development of a high-throughput method for identifying dengue virus serotypes, which is crucial for the management and control of the disease.

Preliminary observations on the characteristics of the owned dog population in Roseau, Dominica.

This article reports findings from interviews with 93 heads of households (38.6% of all households) who owned 148 dogs in Roseau, the capital of The Commonwealth of Dominica. Mixed dogs, of no definable cross, were most common, followed by Rottweiler crosses. The median age of the dogs was 3 years, and 9.4% of the population was over 7 years. Respondents showed a definite preference for keeping male dogs (60%), and most animals were kept for protection (65%). Almost 30% of the dogs were allowed to roam. With 8.5% of the dogs neutered and 7 puppies per litter being born, the owned population produces more dogs than are required to maintain its size and so can provide recruits to the "stray" dog population. Comparisons with studies elsewhere in the Caribbean region (Fielding & Plumridge, 2005; Ortega-Pacheco et al. (in press) suggest that environmental effects rather than the level of care offered are primarily responsible for controlling the dog population.

Human T-cell lymphotropic virus type 1 (HTLV-1) and lymphoid malignancies in Dominica: a seroprevalence study.

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in certain regions of the world where it is associated with lymphoid malignancies. Herein we aim to describe the seroprevalence of HTLV-1 in lymphoid malignancies in Dominica. We carried out a 10-year retrospective study of histologically proven hematologic malignancies and HTLV-1 seropositivity at the Princess Margaret Hospital, Dominica. Ninety-eight cases were reviewed (59% males, 41% females), ranging in age from 3 to 91 years. HTLV-1 was seropositive in 38.6% (31/80) of all hematologic malignancies. Three of 6 cases of Hodgkin disease (50%), 16 of 36 (44.4%) of non-Hodgkin lymphoma, and 3 out of 8 unclassified lymphomas (37.5%) were seropositive; all 6 cases (100%) of acute adult T-cell leukemia/lymphoma (ATLL) were seropositive. One case each of chronic lymphocytic leukemia and myeloproliferative disorder was seropositive. HTLV-1-seropositive lymphomas presented at a younger age than did seronegative cases. Thus, HTLV-1 is significantly associated with lymphoid malignancies in Dominica, and further studies are needed before a causal relationship with Hodgkin disease can be established.

Intestinal parasitoses.

BACKGROUND: Intestinal parasitoses is a clinical problem in the developing world and severe parasitaemia may be associated with retroviruses. OBJECTIVE: Studies on intestinal parasitoses were conducted in Dominica, and the health implications in an HTLV-1 endemic area were discussed. METHOD OF STUDY: A retrospective study of data of stool samples analysed at the parasitology unit of the medical laboratory services of Princess Margaret Hospital, Dominica, was conducted in January-December 1999. RESULTS: Parasites were found in 393 out of 3,752 stool samples (10.47%). The main parasites were Entamoeba coli, 1.4% (51/3,752); hookworm, 1.5% (56/3,752); Giardia lamblia, 1.4% (51/3,752); Strongyloides stercoralis, 1.0% (37/3,752); Ascaris lumbricoides, 0.8% (28/3,752); and Trichuris trichiura, 0.9% (34/3,752). CONCLUSION: Intestinal parasites are still endemic in Dominica, but significant reduction in prevalence has occurred over the last two decades.

Hospital admissions for human T-cell lymphotropic virus type-1 (HTLV-1) associated diseases in Dominica.

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that is endemic in certain regions of the world, and may account for significant morbidity and mortality among hospitalised patients. Sixty six HTLV-1 seropositive patients admitted to hospital with HTLV-1 associated diseases from 1995-99 were studied. HTLV-1 screening was done with ELISA and confirmed on western blot testing. There were 32 females (48.5%) and 34 males (51.5%). The mean age was 56 years and the age range was 9-89 years. The main associated diseases were tropical spastic paraparesis or HTLV-1 associated myelopathy in 18.2% of cases, acute form of adult T-cell leukaemia/lymphoma 7.6%, lymphomas 15.2%, and ectoparasites/endoparasites in 40.9%. HTLV-1 is associated with diseases in Dominica and association with severe forms of strongyloidiasis and scabies is particularly noted.

Three scleractinian coral diseases in Dominica, West Indies: distribution, infection patterns and contribution to coral tissue mortality.

Coral diseases have been documented in many areas of the Caribbean, but studies in the eastern Caribbean region have been lacking. The prevalence, distribution patterns and contribution to the mortality of coral tissue by black band discase (BBD), white plague (WP) and dark spots disease (DSD) were examined at five reef sites along the west coast of Dominica. 185 of the 325 diseased colonies recorded between March and August 2000, in a survey area of 5884 m2, were WP. This disease contributed to 89% of the total 4.08 m2 of tissue mortality caused by diseases during the survey period. WP also affected the largest average tissue surface area (relative to colony size) per colony and exhibited the largest average tissue loss per infection when compared to BBD and DSD. The species most susceptible to WP and BBD in Dominica differed from most other described Caribbean locations with Siderastrea siderea being most susceptible. S. siderea was also the only species noted to be susceptible to DSD. Measurements of colony size revealed that each disease affected the larger colonies of some coral species. Comparisons between disease prevalence at each site and various physical parameters, including temperature, wave height, depth, and current patterns, did not exhibit significant correlations. The lack of a direct correlation between temperature and disease prevalence indicates that there are other seasonal factors contributing to the higher prevalence of diseases recorded during the summer months in Dominica. WP prevalence at each site was positively correlated to the relative species abundances of the species most susceptible to WP. This was the dominant factor in determining site-specific disease densities of this disease and may therefore be a valuable predictive and management tool. There were no correlations between BBD or DSD and the relative abundances of susceptible species. The spatial distribution patterns of WP, BBD and DSD were clustered, which is a distribution pattern that suggests an infectious disease.

Internalized racism, body fat distribution, and abnormal fasting glucose among African-Caribbean women in Dominica, West Indies.

The current study examined the relationship of internalized racism to glucose intolerance in a population of Afro-Caribbean women aged 18 to 55. Also of interest was whether this relationship would be differentially influenced by the type of body fat distribution or confounded by the level of hostility. A total of 244 women were selected from a systematic sample of households on the island of Dominica, West Indies. Demographic data together with information on internalized racism were collected by questionnaire. Anthropometric information and fasting blood glucose were also measured. Women with high levels of internalized racism exhibited an increased risk of elevated fasting glucose compared to those with low levels of internalized racism (odds ratio (OR) = 2.4; 95% confidence interval (CI) = 1.1-5.5). There was no difference in mean body mass index (BMI) by level of internalized racism. However those with high internalized racism had a significantly larger waist circumference after adjusting for age, education, hostility, and elevated fasting glucose status. In multivariate analyses controlling for age, education, hostility, and either weight or BMI, internalized racism remained independently associated with elevated fasting glucose. However, once waist circumference was included in the model, the relationship of internalized racism to elevated fasting glucose was not statistically significant. This study demonstrates a significant relationship between internalized racism and abnormal levels of fasting glucose which may be mediated through abdominal fat. The exact nature of the relationship of internalized racism to glucose intolerance may be an important area of future study.

Should body size preference be a target of health promotion efforts to address the epidemic of obesity in Afro-Caribbean women?

OBJECTIVE: To determine if 1) Afro-Caribbean women prefer large body sizes, 2) the body size preference of Afro-Caribbean men and women are associated, 3) women's preferences are associated with increased risk of obesity or with weight management behaviors. DESIGN: Population samples of 314 and 487 women, ages 20-55 years, were recruited on Barbados and Dominica with response rates of 74% and 77%, respectively. Body size preferences, stress related variables, and demographic data were ascertained by questionnaire. Height and weight were also measured. On Barbados, body preference data were collected from male partners of participants, and data on intentions to perform weight management behaviors were collected from 175 women. RESULTS: Most women preferred body sizes within normal limits, although women on Dominica had a slightly larger ideal body size (IBS) than did Barbadian women (P<.05). On both islands, the size that women thought men preferred was related to their IBS (P<.0001). Likewise, IBS was associated with increased odds of being overweight (P<.001), however most overweight women (>75%) wanted to be smaller. IBS was not related to the intention to exercise or to eat high fat foods. CONCLUSIONS: It is unlikely that body size preference poses a barrier to intervention efforts to reduce the prevalence of overweight in Afro-Caribbean women.

Health status of the elderly in the Marigot Health District, Dominica.

The health status and the prevalence of hypertension, diabetes mellitus, glaucoma and visual disorders of 123 elderly people (56 men, 67 women) in the Marigot Health District, Dominica, were assessed by means of four questionnaires; collection of data from their medical records; physical examination, measurement of blood pressure, visual acuity and intra-ocular pressure (IOP); and testing for glucosuria. The overall health status was good, but 20% were dependent on care. 74% were independent in the activities in daily life, with only moderate limitations in activities. The health status decreased considerably in those over 75 years of age. There were slight perceived differences in health status between men and women. About 40% of the study population were known to be hypertensive, and another 13% had an elevated blood pressure on examination. Diabetes mellitus was present in 15%. 20% had a visual acuity of 0.1 or below, and 10% had an elevated IOP. During the study, a considerable number of new cases of hypertension, diabetes mellitus and elevated IOP were diagnosed. 50% of the study population who were on medication used this more than as prescribed. This study indicates a high prevalence of the secondary complications of hypertension, diabetes mellitus, cataract, glaucoma and osteo-arthritis that cause disability and dependency in the elderly population. Education, diagnosis at an early stage and appropriate treatment of these disorders may prevent or delay their development. We sugggest the development of a programme oriented approach of primary health care for the elderly to support this.

Health status of the elderly in the Marigot Health District, Dominica

The health status and the prevalence of hypertension, diabetes mellitus, glaucoma and visual disorders of 123 elderly people (56 men, 67 women) in the Marigot Health District, Dominica, were assessed by means of four questionnaires: collection of data from their medical records; physical examination, measurement of blood pressure, visual acuity and intra-ocular pressure (IOP); and testing for glucosuria. The overall health status was good, but 20 percent were dependent on care. 74 percent were independent in the activities in daily life, with only moderate limitations in activities. The health status decreased considerably in those over 75 years of age. There were slight perceived differences in health status between men and women. About 40 percent of the study population were known to be hypertensive, and another 13 percent had an elevated blood pressure on examination. Diabetes mellitus was present in 15 percent. 20 percent had a visual acuity of 0.1 or below, and 10 percent had an elevated IOP. During the study, a considerable number of new cases of hypertension, diabetes mellitus and elevated IOP were diagnosed. 50 percent of the study population who were on medication used this more than as prescribed. This study indicates a high prevalence of the secondary complications of hypertension, diabetes mellitus, cataract, glaucoma and osteo-arthritis that cause disability and dependency in the elderly population. Education, diagnosis at an early stage and appropriate treatment of these disorders may prevent or delay their development. We suggest the development of a programme oriented approach of primary health care for the elderly to support this.(AU)