Zoonotic helminths of dogs and risk factors associated with polyparasitism in Grenada, West Indies.

Canine soil-transmitted helminths (STHs) cause important zoonoses in the tropics, with varying degrees of intensity of infection in humans and dogs. This study aimed to investigate the prevalence and associated risk factors for STHs in community dogs residing in Grenada, West Indies. In May 2021, 232 canine fecal samples were examined for zoonotic helminths by microscopy (following flotation), and genomic DNA from a subset of 211 of these samples were subjected to multiplex qPCR for the detection and specific identification of hookworms, Toxocara spp. and Strongyloides. Microscopic examination revealed that 46.5% (108/232, 95% CI 40­52.9), 9% (21/232, 95% CI 5.35­12.7) and 5.2% (12/232, 95% CI 2.3­8) of the samples contained eggs of Ancylostoma spp., Toxocara spp. and Trichuris vulpis, respectively. Multiplex qPCR revealed that, 42.2% (89/211, 95% CI 35.5­48.8) were positive for at least 1 zoonotic parasite. Of these, 40.8% (86/211, 95% CI 34.1­47.3) of samples tested positive for Ancylostoma spp., 36% (76/211, 95% CI 29.5­42.9) were positive for A. caninum, 13.3% (28/211, 95% CI 9­18.6) for A. ceylanicum, 5.7% for T. canis (12/211, 95% CI 2.97­8.81) and 1% (2/211, 95% CI 0­2.26) for Strongyloides spp. (identified as S. stercoralis and S. papillosus by conventional PCR-based Sanger sequencing). Using a multiple logistic regression model, a low body score and free-roaming behaviour were significant predictors of test-positivity for these parasitic nematodes in dogs (P < 0.05). Further studies of zoonotic STHs in humans should help elucidate the public health relevance of these parasites in Grenada.

Ancylostoma ceylanicum Hookworms in Dogs, Grenada, West Indies.

Ancylostoma ceylanicum hookworms are recognized agents of human infection in the Asia-Pacific region. We investigated prevalence of zoonotic hookworm infections in dogs in Grenada in 2021; 40.8% were infected by hookworms, including Ancylostoma ceylanicum. Surveillance of this parasite in dogs and humans is needed in tropical/subtropical countries in the Americas.

The epidemiology and control of Toxocara canis in puppies.

Toxocara canis is a helminth zoonosis that is estimated to infect more than 100 million dogs and 1 billion people, mostly in the tropics. Humans can be infected by accidentally ingesting embryonated T. canis eggs from the environment or occasionally after ingesting L3 larvae from paratenic hosts. This study investigated the importance of vertical transmission and the role of puppies in the epidemiology of T. canis through the examination of fecal samples from dogs less than one year of age in Grenada, West Indies, a small island tropical developing country. Samples were stored at 4 °C or in 10% formalin until microscopic examination for helminth eggs or using a rapid antigen test for the presence of protozoan species. A knowledge, attitudes and practices study was completed among dog owners, physicians and veterinary students. Of 306 dogs less than one year of age, 147 (48%) were found to have T. canis eggs. Vertical transmission was indicated by the proportion of infected dogs increasing from 50% at two weeks of age (from in utero transmission) to 70% by 12 weeks (in utero and lactogenic transmission). After 12 weeks the positivity rate dropped rapidly with no dogs over 40 weeks of age being infected. As T. canis eggs were found in puppy feces at two weeks of age, initial treatment of puppies should begin earlier, at twelve days post-partum, than currently recommended to prevent shedding of eggs. Perhaps even more importantly, treatment of pregnant dogs, preventing vertical transmission, would have a major impact on the control of T. canis infection. Knowledge of T. canis and other zoonotic helminths such as Ancylostoma caninum was found to be low among dog owners, physicians and veterinary students. None of the dog owners treated their dogs for helminths, all were unaware of the risk of zoonoses, and only 9% picked up dog feces. Efforts to prevent vertical transmission and to increase awareness and knowledge of these zoonoses could result in reducing their public health impact.

Defining the Need for Dermatologic Surgery Global Health in an Afro-Caribbean Country.

BACKGROUND: Dermatologic surgery services are largely absent in Africa and in Afro-Caribbean counties. In the USA, studies of people of African ancestry have demonstrated health care gaps, but there are no data for Africa nor a Afro-Caribbean country. Dermatology surgery has been largely absent from global health because there are few data to demonstrate the need. We sought to determine skin cancer tumor types, and local knowledge and perception in an Afro-Caribbean country. OBJECTIVE: We sought to determine whether there exist knowledge gaps and whether a dermatology surgery medical missions program would improve the health of Afro-Caribbean people. METHODS: First, we conducted a survey of knowledge and behaviors related to skin cancer. Second, we analyzed the number and types of tumors treated during a multi-year surgical dermatology project. RESULTS: In the survey, 62% did not know what melanoma was. Eighty-one percent did not think skin cancer is preventable. Of 163 surgical specimens, 64 were malignancies with 91% related to UV exposure. CONCLUSION: There is a need for a skin cancer treatment and education program in a country of mostly African-ancestry people.

Global Prevalence Estimates of Toxascaris leonina Infection in Dogs and Cats.

Toxascaris leonina is an ascaridoid nematode of dogs and cats; this parasite affects the health of these animals. This study estimated the global prevalence of Ta. leonina infection in dogs and cats using random effects meta-analysis as well as subgroup, meta-regression and heterogeneity analyses. The data were stratified according to geographical region, the type of dogs and cats and environmental variables. A quantitative analysis of 135 published studies, involving 119,317 dogs and 25,364 cats, estimated prevalence rates of Ta. leonina in dogs and cats at 2.9% and 3.4%, respectively. Prevalence was highest in the Eastern Mediterranean region (7.2% for dogs and 10.0% for cats) and was significantly higher in stray dogs (7.0% vs. 1.5%) and stray cats (7.5% vs. 1.8%) than in pets. The findings indicate that, worldwide, ~26 million dogs and ~23 million cats are infected with Ta. leonina; these animals would shed substantial numbers of Ta. leonina eggs into the environment each year and might represent reservoirs of infection to other accidental or paratenic hosts. It is important that populations of dogs and cats as well as other canids and felids be monitored and dewormed for Ta. leonina and (other) zoonotic helminths.

Global prevalence of Toxocara infection in dogs.

Dogs serve as the most important definitive hosts for Toxocara canis-a causative agent of human toxocariasis and one of the most widespread zoonotic helminth worldwide. The present study was undertaken to assess the global prevalence of T. canis infection in dogs. PubMed, Scopus, Web of Science, EMBASE and SciELO were searched to identify relevant studies. A random-effects model was used to estimate the overall and the subgroup-pooled prevalences across studies, and heterogeneity was assessed via the I2 test. The data were categorized according to WHO-region, different types of dogs, risk factors and environmental variables. From a total of 4370 peer-reviewed publications, 229 articles that studied 13,010,004 dogs in 60 countries met the final inclusion criteria. The overall prevalence of Toxocara infection in dogs was 11.1% (95% CI, 10.6-11.7%). The estimated prevalence in the different WHO-regions ranged from 6.4% to 19.2%: Eastern Mediterranean (19.2%, 13.7-25.5%), Africa (18.5%, 13.7-23.9%), South-East Asia (11.9%, 6.8-18.2%), North America (11.1%, 10.6-11.7%), South America (10.9%, 7.6-14.6%), Europe (10.8%, 8.9-12.9%) and Western Pacific (6.4%, 3.3-10.2%). Young (<1 year of age), stray, rural and male dogs had a significantly (P<0.001) higher prevalence of infection than older, pet, urban or female dogs. The prevalence was higher in low income countries and regions at a low geographical latitude, close to the equator, characterized as having tropical climates. From this review, it is estimated that ≥100 million dogs are infected with Toxocara around the world. This highlights the need for an increased focus on implementing affordable, appropriate control programs to reduce the public health threat of toxocariasis as a zoonosis of global importance.

Global prevalence of Toxocara infection in cats.

Zoonotic parasites, including Toxocara species, of pet and stray cats are of public health importance. Justification for, and the design and implementation of prevention and control of human toxocariasis may benefit from an understanding of the zoonotic potential and prevalence of parasites in this definitive host species. This is the first systematic review and meta-analysis of cross-sectional studies, conducted to estimate the prevalence of Toxocara infection(s) in cats by geographical location, type (rural vs urban and stray vs pet), gender and age. Pooled data were assessed using a random effects-model as well as several meta-regression and stratified analyses conducted. Of 1733 peer-reviewed articles, 143 were included in this review and represented 2,158,069 cats from 51 countries. The global pooled (95% CI) prevalence of Toxocara infection in cats was 17.0% (16.1-17.8%), being highest in African (43.3%, 28.3-58.4%) and lowest in South American (12.6%, 8.2-17.0%) countries. In other WHO regions, prevalence rates of Toxocara were as follows: Eastern Mediterranean (21.6%, 15.1-28.1%), North America (18.3%, 15.4-21.2%), Europe (17.8%, 15.9-19.7%), Western Pacific (17.3%, 14.7-19.9%), and South-East Asia (14.9%, 9.8-20.1%). Prevalence of Toxocara was higher in low-income tropical countries and also in stray (28.6%, 25.1-32.1%) and young (≤12 months of age) (27.7%, 23.4-32.0%) cats than in pet (11.6%, 10.7-12.5%) and older cats (>12 months of age) (23.8%, 14.8-32.7%). This review indicates that ~118-150 million cats worldwide serve as definitive hosts of Toxocara, shedding eggs and thus contributing to the public health risk of human infection. Prevention and control of this zoonosis in cats should receive greater attention by health officials and cat owners, particularly in countries where risk factors and prevalence are highest.

Understanding the relation between Zika virus infection during pregnancy and adverse fetal, infant and child outcomes: a protocol for a systematic review and individual participant data meta-analysis of longitudinal studies of pregnant women and their infants and children.

INTRODUCTION: Zika virus (ZIKV) infection during pregnancy is a known cause of microcephaly and other congenital and developmental anomalies. In the absence of a ZIKV vaccine or prophylactics, principal investigators (PIs) and international leaders in ZIKV research have formed the ZIKV Individual Participant Data (IPD) Consortium to identify, collect and synthesise IPD from longitudinal studies of pregnant women that measure ZIKV infection during pregnancy and fetal, infant or child outcomes. METHODS AND ANALYSIS: We will identify eligible studies through the ZIKV IPD Consortium membership and a systematic review and invite study PIs to participate in the IPD meta-analysis (IPD-MA). We will use the combined dataset to estimate the relative and absolute risk of congenital Zika syndrome (CZS), including microcephaly and late symptomatic congenital infections; identify and explore sources of heterogeneity in those estimates and develop and validate a risk prediction model to identify the pregnancies at the highest risk of CZS or adverse developmental outcomes. The variable accuracy of diagnostic assays and differences in exposure and outcome definitions means that included studies will have a higher level of systematic variability, a component of measurement error, than an IPD-MA of studies of an established pathogen. We will use expert testimony, existing internal and external diagnostic accuracy validation studies and laboratory external quality assessments to inform the distribution of measurement error in our models. We will apply both Bayesian and frequentist methods to directly account for these and other sources of uncertainty. ETHICS AND DISSEMINATION: The IPD-MA was deemed exempt from ethical review. We will convene a group of patient advocates to evaluate the ethical implications and utility of the risk stratification tool. Findings from these analyses will be shared via national and international conferences and through publication in open access, peer-reviewed journals. TRIAL REGISTRATION NUMBER: PROSPERO International prospective register of systematic reviews (CRD42017068915).

Clinical, Serological, and Molecular Observations from a Case Series Study during the Asian Lineage Zika Virus Outbreak in Grenada during 2016.

This paper describes the spatial and temporal distribution of cases, demographic characteristics of patients, and clinical manifestations of Zika virus (ZIKV) during the 2016 outbreak in Grenada. The first reported case was recorded in St. Andrew Parish in April, and the last reported case was seen in November, with peak transmission occurring in the last week of June, based on test results. Data were collected from a total of 514 patients, of whom 207 (40%) tested positive for ZIKV. No evidence was found that testing positive for ZIKV infection was related to age, gender, or pregnancy status. Clinical presentation with rash (OR = 2.4, 95% CI = 1.5 to 3.7) or with lymphadenopathy (OR = 1.7, 95% CI = 1.0 to 2.9) were the only reported symptoms consistent with testing positive for ZIKV infection. During the Zika outbreak, the infection rate was 20 clinical cases per 10,000 in the population compared to 41 cases per 10,000 during the chikungunya outbreak in Grenada in 2014 and 17 cases per 10,000 during the dengue outbreak in 2001-2002. Even though the country has employed vector control programs, with no apparent decrease in infection rates, it appears that new abatement approaches are needed to minimize morbidity in future arbovirus outbreaks.

Cystic Echinococcosis in Turkana, Kenya: The Role of Cross-Sectional Screening Surveys in Assessing the Prevalence of Human Infection.

Cystic echinococcosis (CE) is a neglected zoonotic disease caused by Echinococcus granulosus. Infection leads to formation of cysts within the viscera of the human host. In the 1980s, the transhumant population of northwest Turkana, Kenya, was found to have the highest prevalence of CE in the world. In 1983, AMREF Health Africa and the Kenya Medical and Research Institute launched a CE Control Program in northwest Turkana, screening and treating the local people. This epidemiological study of CE in Turkana analyses approximately 30 years of surveillance and surgical data. Cyst data were categorized using the World Health Organization CE ultrasound classification system before being analyzed for cyst, patient, and population characteristics, and surveillance data from 1985 are compared with more recent surveillance data to assess changes in prevalence in the control region since the commencement of control activities. In 1985, the prevalence of CE among the Turkana was 5.6%. In 2010-2011 and 2011-2012, calculated CE prevalence rates were 1.9% and 3.8%, respectively. Since the 1980s, the age distribution of people with CE in Turkana has shifted: initially, cases of CE appeared predominantly within younger age groups, but recent data reveal a higher prevalence within older age groups. The frequency of infection in females also significantly decreased. The reduction in CE prevalence from 5.6% in the 1980s to 1.9-3.8% in 2010-2012 and the shift in age distribution of CE-infected individuals over time indicate that the prevalence of CE in Turkana has decreased since the control program began.

Expert Reliability for the World Health Organization Standardized Ultrasound Classification of Cystic Echinococcosis.

Cystic echinococcosis (CE), a parasitic zoonosis, results in cyst formation in the viscera. Cyst morphology depends on developmental stage. In 2003, the World Health Organization (WHO) published a standardized ultrasound (US) classification for CE, for use among experts as a standard of comparison. This study examined the reliability of this classification. Eleven international CE and US experts completed an assessment of eight WHO classification images and 88 test images representing cyst stages. Inter- and intraobserver reliability and observer performance were assessed using Fleiss' and Cohen's kappa. Interobserver reliability was moderate for WHO images (κ = 0.600, P < 0.0001) and substantial for test images (κ = 0.644, P < 0.0001), with substantial to almost perfect interobserver reliability for stages with pathognomonic signs (CE1, CE2, and CE3) for WHO (0.618 < κ < 0.904) and test images (0.642 < κ < 0.768). Comparisons of expert performances against the majority classification for each image were significant for WHO (0.413 < κ < 1.000, P < 0.005) and test images (0.718 < κ < 0.905, P < 0.0001); and intraobserver reliability was significant for WHO (0.520 < κ < 1.000, P < 0.005) and test images (0.690 < κ < 0.896, P < 0.0001). Findings demonstrate moderate to substantial interobserver and substantial to almost perfect intraobserver reliability for the WHO classification, with substantial to almost perfect interobserver reliability for pathognomonic stages. This confirms experts' abilities to reliably identify WHO-defined pathognomonic signs of CE, demonstrating that the WHO classification provides a reproducible way of staging CE.

Zoonoses and one health: a review of the literature.

Background. One health is a concept that was officially adopted by international organizations and scholarly bodies in 1984. It is the notion of combining human, animal, and environmental components to address global health challenges that have an ecological interconnectedness. Methods. A cross-sectional study of the available literature cited was conducted from January 1984 when the one health concept was adopted till December 2012 to examine the role of the one health approach towards zoonoses. Inclusion criteria included publications, professional presentations, funding allocations, official documentation books, and book chapters, and exclusion criteria included those citations written outside the period of review. Results. A total of 737 resources met the inclusion criteria and were considered in this review. Resources showed a continuous upward trend for the years from 2006 to 2012. The predominant resources were journal publications with environmental health as the significant scope focus for one health. There was also an emphasis on the distribution of the work from developed countries. All categories of years, resources, scopes, and country locale differed from the means (P = 0.000). Year of initiative, scope, and country locale showed a dependent relationship (P = 0.022, P = 0.003, and P = 0.021, resp.). Conclusion. Our findings demonstrate the rapid growth in embracing the concept of one health, particularly in developed countries over the past six years. The advantages and benefits of this approach in tackling zoonoses are manifold, yet they are still not seemingly being embraced in developing countries where zoonoses have the greatest impact.

The epidemiology and public health importance of toxocariasis: a zoonosis of global importance.

Toxocariasis, caused by infection with larvae of Toxocara canis, and to a lesser extent by Toxocara cati and other ascaridoid species, manifests in humans in a range of clinical syndromes. These include visceral and ocular larva migrans, neurotoxocariasis and covert or common toxocariasis. Toxocara canis is one of the most widespread public health and economically important zoonotic parasitic infections humans share with dogs, cats and wild canids, particularly foxes. This neglected disease has been shown through seroprevalence studies to be especially prevalent among children from socio-economically disadvantaged populations both in the tropics and sub-tropics and in industrialised nations. Human infection occurs by the accidental ingestion of embryonated eggs or larvae from a range of wild and domestic paratenic hosts. Most infections remain asymptomatic. Clinically overt infections may go undiagnosed, as diagnostic tests are expensive and can require serological, molecular and/or imaging tests, which may not be affordable or available. Treatment in humans varies according to symptoms and location of the larvae. Anthelmintics, including albendazole, thiabendazole and mebendazole may be given together with anti-inflammatory corticosteroids. The development of molecular tools should lead to new and improved strategies for the treatment, diagnosis and control of toxocariasis and the role of other ascaridoid species in the epidemiology of Toxocara spp. Molecular technologies may also help to reveal the public health importance of T. canis, providing new evidence to support the implementation of national control initiatives which have yet to be developed for Toxocara spp. A number of countries have implemented reproductive control programs in owned and stray dogs to reduce the number of young dogs in the population. These programs would positively impact upon T. canis transmission since the parasite is most fecund and prevalent in puppies. Other control measures for T. canis include the regular and frequent anthelmintic treatment of dogs and cats, starting at an early age, education and enforcement of laws for the disposal of canine faeces, dog legislation and personal hygiene. The existence of wild definitive and paratenic hosts complicates the control of T. canis. Increasing human and dog populations, population movements and climate change will all serve to increase the importance of this zoonosis. This review examines the transmission, diagnosis and clinical syndromes of toxocariasis, its public health importance, epidemiology, control and current research needs.

The socioeconomic burden of parasitic zoonoses: global trends.

Diseases resulting from zoonotic transmission of parasites are common. Humans become infected through food, water, soil and close contact with animals. Most parasitic zoonoses are neglected diseases despite causing a considerable global burden of ill health in humans and having a substantial financial burden on livestock industries. This review aims to bring together the current data available on global burden estimates of parasitic zoonoses and indicate any changes in the trends of these diseases. There is a clear need of such information as interventions to control zoonoses are often in their animal hosts. The costs of such interventions together with animal health issues will drive the cost effectiveness of intervention strategies. What is apparent is that collectively, parasitic zoonoses probably have a similar human disease burden to any one of the big three human infectious diseases: malaria, tuberculosis or HIV in addition to animal health burden. Although the global burden for most parasitic zoonoses is not yet known, the major contributors to the global burden of parasitic zoonoses are toxoplasmosis, food borne trematode infections, cysticercosis, echinococcosis, leishmaniosis and zoonotic schistosomosis. In addition, diarrhoea resulting from zoonotic protozoa may have a significant impact.

Seroprevalence of Toxoplasma gondii in pregnant women and cats in Grenada, West Indies.

Prevalence of antibodies against Toxoplasma gondii was studied in 534 pregnant women and 40 domestic cats in Grenada, West Indies. Antibodies (IgG) for T. gondii were sought in human sera by an enzyme-linked immunosorbent assay and in cat sera by using the modified agglutination test (MAT). Antibodies were found in 57 % of pregnant women. Seroprevalence increased with age; 51% of 15- to 19-yr-old women (100 total) had antibodies versus 60% of 20- to 24-yr-old women (127 total). Antibodies to T. gondii (MAT, 1:25 serum dilution) were found in 35% of cats; titers were 1:25 in 7 cats, 1:50 in 4 cats, and 1:500 in 3 cats. Epidemiological data suggested that the ingestion of food or water contaminated with oocysts was an important mode of transmission of T. gondii to women.

Human behaviour and the epidemiology of parasitic zoonoses.

The behaviour of Homo sapiens has a pivotal role to play in the macro and microepidemiology of emerging or re-emerging parasitic zoonoses. Changing demographics and the concomitant alterations to the environment, climate, technology, land use and changes in human behavior, converge to favour the emergence and spread of parasitic zoonoses. The recent unprecedented movements of people, their animals and their parasites around the world, introduce and mix genes, cultural preferences, customs, and behavioral patterns. The increasing proclivity for eating meat, fish, crabs, shrimp, molluscs raw, undercooked, smoked, pickled or dried facilitates a number of protozoan (Toxoplasma), trematode (Fasciola sp., Paragonimus spp., Clonorchis sp., Opisthorchis spp., Heterophyes sp., Metagonimus sp., Echinostoma spp., Nanophyetus sp.) cestode (Taenia spp, Diphyllobothrum sp.) and nematode (Trichinella spp., Capillaria spp., Gnathostoma spp., Anisakis sp., Parastrongylus spp.) caused zoonoses. The increasing world population and the inability to keep pace with the provision of adequate sanitation and clean, safe drinking water, has led to an increased importance of waterborne zoonoses, such as those caused by Giardia, Cryptosporidium and Toxoplasma. Our close relationship with and the numerous uses to which we put companion animals and their ubiquitous distribution has resulted in dogs and cats unwitting participation in sharing over 60 parasite species including: Giardia, Cryptosporidium, Toxoplasma, most foodborne trematode species, Diphyllobothrum, Echinococcus spp., Ancylostoma and Toxocara. Changing human behaviour through education, to encourage the proper cooking of food, which may have cultural and social significance, will remain as challenging as controlling stray and feral pet populations, improving hygiene levels and the provision of safe drinking water and the proper use of sanctuary facilities. Long pre-patent periods and the normally insidious sub-clinical nature of most zoonoses makes advice requiring behavioural change for their control a difficult task. Our clearer understanding of the heterogeneity of susceptibility to infection, the complex genetic variations of people and parasite species and the development of molecular epidemiological tools is shedding more light on transmission routes and the spectrum of disease that is observed. Improved and new serological, molecular and imaging diagnostic tests and the development of broad spectrum chemotherapeutic agents has led to the attenuation of morbidity and mortality due to parasitic zoonoses in economically advantaged regions. Such advancements, in partnership with supportive behavioural change, has the potential for a sustainable global reduction in the burden of ill health due to parasitic zoonoses. Whether this will materialise is a challenge for us all.

Dengue in Grenada.

OBJECTIVES: Dengue fever is endemic in the country of Grenada and is grossly underreported as a source of morbidity. The goal of this study was to assess the status of dengue fever in a representative community in Grenada. METHODS: Surveys were conducted in the Mont Tout/Grand Anse Valley area in the parish of St. George's from March to June 1996. The objectives of the survey were to: (1) to assess the knowledge, attitudes, and practices (KAP) of residents; (2) to determine the presence of larval and adult Aedes aegypti and their potential breeding sites; and (3) to identify the seroprevalence of specific immunoglobulin G (IgG) dengue antibodies in the local population. RESULTS: Out of the 102 respondents to the KAP survey, 100 of them (98%) reported never having had dengue fever. Of the 75 persons who agreed to have blood samples taken, 70 of them (93%) (95% confidence interval = 85.1%-97.8%) tested positive with the IgG enzyme-linked immunosorbent assay, indicating past exposure. In terms of water storage, 98 of 102 respondents (96%) stored fresh water in containers. The vector survey found 57 of the 102 households (56%) had Ae. aegypti larvae in water containers on their property, and 94 of 102 dwellings (92%) had adult Ae. aegypti mosquitoes indoors. CONCLUSIONS: Although many people were familiar with dengue fever and mosquitoes, the 1996 survey found that their knowledge of the important relationships among mosquitoes, human behavior, and disease transmission was incomplete. Since 1996, continued education efforts have been made in the public school system and with national public health campaigns, yet little effort has been specifically targeted towards our study community. These data suggest Grenada has a need for continued community education that addresses dengue fever transmission and Ae. aegypti reduction.

Dengue in Grenada / El dengue en el país de Granada

Objetivos. La fiebre del dengue es endémica en el país caribeño de Granada y es grande su subnotificación como fuente de morbilidad. El objetivo del presente estudio fue evaluar la situación del dengue en una comunidad representativa de ese país. Métodos. Se llevaron a cabo encuestas en la zona del valle de Mont Tout y de Grand Anse, en la parroquia de St. George's, de marzo a junio de 1996. Los objetivos de las encuestas fueron: 1) explorar los conocimientos, actitudes y prácticas (CAP) de los habitantes; 2) determinar la presencia de formas larvarias y adultas de Aedes aegypti en posibles criaderos, y 3) identificar la seroprevalencia de inmunoglobulina G (IgG) con actividad específica contra el virus del dengue en la población local. Resultados. De las 102 personas que respondieron la encuesta de CAP, 100 (98%) indicaron que nunca habían padecido de fiebre del dengue. De las 75 personas que consintieron que se les sacaran muestras de sangre, 70 (93%) (intervalo de confianza de 95% = 85,1%­97,8%) tuvieron resultados positivos en la prueba de inmunoadsorción enzimática para la detección de IgG, señal de que habían tenido una exposición anterior. En lo que respecta al almacenamiento del agua, 98 de las 102 personas (96%) encuestadas almacenaban agua fresca en recipientes. La encuesta de vectores reveló que en 57 de las 102 viviendas (56%) había larvas de Ae. Aegypti en recipientes de agua en la propiedad, y en 94 de las 102 viviendas (92%) se encontraron mosquitos Ae. aegypti adultos en el interior. Conclusiones. A pesar de que muchas personas estaban familiarizadas con la fiebre del dengue y el mosquito vector, la encuesta de 1996 reveló en ellas conocimientos incompletos acerca de las relaciones importantes entre los mosquitos, los hábitos del ser humano y la transmisión de la enfermedad. Desde 1996 se han puesto en marcha de continuo iniciativas educativas en las escuelas públicas y mediante campañas sanitarias a escala nacional, pero pocas han estado dirigidas específicamente a la comunidad aquí estudiada. Estos datos indican que el país de Granada necesita un sistema de educación comunitaria continua que se oriente a reducir la transmisión de la fiebre del dengue y la población de Ae. aegypti

Objectives. Dengue fever is endemic in the country of Grenada and is grossly underreported as a source of morbidity. The goal of this study was to assess the status of dengue fever in a representative community in Grenada. Methods. Surveys were conducted in the Mont Tout/Grand Anse Valley area in the parish of St. George's from March to June 1996. The objectives of the survey were to: (1) to assess the knowledge, attitudes, and practices (KAP) of residents; (2) to determine the presence of larval and adult Aedes aegypti and their potential breeding sites; and (3) to identify the seroprevalence of specific immunoglobulin G (IgG) dengue antibodies in the local population. Results. Out of the 102 respondents to the KAP survey, 100 of them (98%) reported never having had dengue fever. Of the 75 persons who agreed to have blood samples taken, 70 of them (93%) (95% confidence interval = 85.1%­97.8%) tested positive with the IgG enzyme-linked immunosorbent assay, indicating past exposure. In terms of water storage, 98 of 102 respondents (96%) stored fresh water in containers. The vector survey found 57 of the 102 households (56%) had Ae. aegypti larvae in water containers on their property, and 94 of 102 dwellings (92%) had adult Ae. aegypti mosquitoes indoors. Conclusions. Although many people were familiar with dengue fever and mosquitoes, the 1996 survey found that their knowledge of the important relationships among mosquitoes, human behavior, and disease transmission was incomplete. Since 1996, continued education efforts have been made in the public school system and with national public health campaigns, yet little effort has been specifically targeted towards our study community. These data suggest Grenada has a need for continued community education that addresses dengue fever transmission and Ae. aegypti reduction

Performance characteristics and quality control of community based ultrasound surveys for cystic and alveolar echinococcosis.

The probability of disease given the results of a test, is called the predictive value of the test. The predictive value of a test is not a property of the test itself but will vary according to the prevalence of the disease in the studied population. The positive predictive value (PPV) is the probability that the subject tested has the disease given that a positive result is obtained. The negative predictive value (NPV) is the probability that the subject tested is normal given that a negative result is obtained. As the prevalence of a disease in a population approaches zero so does the PPV and most of the positive cases will be 'false positives'. Conversely the NPV will be very high at low prevalences and there will be few 'false negative' results. The sensitivity and specificity of a test are properties of the test and do not vary with prevalence. The higher the sensitivity and specificity of a particular test the greater the predictive values will be at any given prevalence of the disease. Ultrasound (US) is increasingly used for detecting lesions due to cystic and alveolar echinococcosis (CE and AE) and portable US scanners facilitate community based mass screening surveys in remote rural communities. Screening is justified with AE and CE in endemic areas as diagnosis at an early stage can lead to a better prognosis following treatment. The sensitivity and specificity of US has been reported to be between 88-98% and 95-100% respectively for CE and the sensitivity is a little higher for AE. Both species have pathognomonic signs on US and the technique is considered to be the 'gold standard' although it is still an imperfect test. Clinical, laboratory and epidemiological data also play an important role in the diagnosis of CE and AE. US results where possible, should be evaluated in relation to these findings. Suspected CE and AE images, may benefit from the use of other imaging techniques such as magnetic resonance imaging, computerised tomography and in the case of AE angiography or cholangiography. Immunological tests or molecular biological techniques also provide a useful back up, especially for AE. As sensitivity and specificity are properties of the US diagnostic test they should not vary if the case mix reported in different studies remains the same. The use of the WHO standardised US classifications for CE and AE should be used so that the properties of the test are standardised. Quality control of field based studies will depend on geographical variations in the case mix and the relative proportions of cyst types without pathognomonic signs. The latter will have the most bearing on variations in specificity, as would the use of different classifications. Inter- and intra-observer variability and differences in prevalence will affect the performance of US in different endemic settings. Community based surveys must adhere to the highest ethical standards and the outcome of surveys should result in appropriate treatment and follow-up strategies for all infected individuals and suspected cases found during the surveys.

Combined ultrasound and serologic screening for hepatic alveolar echinococcosis in central China.

Alveolar echinococcosis (AE), caused by Echinococcus multilocularis, is a zoonotic helminthic disease that can mimic malignancy. In the 1970s, foci of the disease were found in central China. The aim of the present study was to estimate the prevalence of AE in humans in 2 districts of south Gansu Province, China, by use of ultrasound and Echinococcus serology. After answering an epidemiological questionnaire, 2,482 volunteers from 28 villages underwent ultrasound. Serology via enzyme-linked immunosorbent assay for antibody activity was performed on whole blood collected on filter paper in all subjects; on serum from subjects with an abnormal ultrasound image; and on randomly chosen subjects that either had no lesions or had atypical lesions. At least one (25.3%) abnormal ultrasound image was observed in 630 of the subjects screened. A typical lesion of progressive AE was found in 84 subjects (3.4%). Serologies were positive in 77 (96%) of 80 of patients who had lesions typical of progressive AE. Ultrasound is useful for screening for AE in endemic regions.