Epidemiology of Chagas disease in Ecuador. A brief review

Chagas disease is a complex public health problem that has been underestimated in Ecuador. Here we review the relevant published information, and present unpublished and new data that help to understand the current Chagas disease epidemiological situation and its evolution in the country. Three main characteristics have been identified: (i) persistence of Trypanosoma cruzi transmission in already known foci; (ii) a marked endemicity in some urban areas of Guayaquil; and (iii) the transformation of new Amazon foci into truly endemic areas. The situation in other suspect areas remains uncertain. Five Triatominae species have been implicated in the transmission of T. cruzi to people in Ecuador (Triatoma dimidiata, Rhodnius ecuadoriensis, R. pictipes, R. robustus and Panstrongylus geniculatus), but some others may also play a role in some areas (P. rufotuberculatus, P. howardi, T. carrioni and P. chinai). Other Triatominae reported seem to have little or no epidemiological relevance (T. venosa, T. dispar, Eratyrus mucronatus, E. cuspidatus, P. lignarius and Cavernicola pilosa). High frequency of acute cases and severe chronic disease has been observed. Although cardiomyopathy is more frequent, serious digestive disease is also present. It is estimated that around 120,000-200,000 people may be infected. 2.2 to 3.8 million people are estimated to live under transmission risk conditions.

Epidemiology of small intestinal atresia in Europe: a register-based study.

BACKGROUND: The epidemiology of congenital small intestinal atresia (SIA) has not been well studied. This study describes the presence of additional anomalies, pregnancy outcomes, total prevalence and association with maternal age in SIA cases in Europe. METHODS: Cases of SIA delivered during January 1990 to December 2006 notified to 20 EUROCAT registers formed the population-based case series. Prevalence over time was estimated using multilevel Poisson regression, and heterogeneity between registers was evaluated from the random component of the intercept. RESULTS: In total 1133 SIA cases were reported among 5126, 164 registered births. Of 1044 singleton cases, 215 (20.6%) cases were associated with a chromosomal anomaly. Of 829 singleton SIA cases with normal karyotype, 221 (26.7%) were associated with other structural anomalies. Considering cases with normal karyotype, the total prevalence per 10 000 births was 1.6 (95% CI 1.5 to 1.7) for SIA, 0.9 (95% CI 0.8 to 1.0) for duodenal atresia and 0.7 (95% CI 0.7 to 0.8) for jejunoileal atresia (JIA). There was no significant trend in SIA, duodenal atresia or JIA prevalence over time (RR=1.0, 95% credible interval (CrI): 1.0 to 1.0 for each), but SIA and duodenal atresia prevalence varied by geographical location (p=0.03 and p=0.04, respectively). There was weak evidence of an increased risk of SIA in mothers aged less than 20 years compared with mothers aged 20 to 29 years (RR=1.3, 95% CrI: 1.0 to 1.8). CONCLUSION: This study found no evidence of a temporal trend in the prevalence of SIA, duodenal atresia or JIA, although SIA and duodenal atresia prevalence varied significantly between registers.

Molecular epidemiology of methicillin resistant Staphylococcus aureus isolated from newborns in a hospital in Rio de Janeiro, Brazil

Methicillin resistant Staphylococcus aureus (MRSA) is an organism that is frequently transmitted in hospitals and perinatal units. The MRSA is considered a public health problem in neonatology because of its strong potential for dissemination in the wards associated with high rates of morbidity and mortality. In this study we describe the bacteriological, epidemiological and molecular characteristics of MRSA isolated from anterior nares and blood cultures of newborns hospitalized in a public maternity hospital in the city of Rio de Janeiro, Brazil. The frequency of MRSA isolated from nasal swabs of newborns was 47.8% (43/90). The genetic analysis of MRSA strains from anterior nares, showed 8 different pulsed field gel electrophoresis patterns (PFGE). Upon analysis of PFGE patterns of the 12 MRSA strains isolated from blood cultures, 8 different patterns were observed, 9 (75%) strains were genetic related to nasal secretion isolates patterns. In conclusion, our data demonstrate the importance of screening of newborns for the presence of MRSA in Brazilian hospitals and the usefulness of genetic typing of these pathogen during epidemiologic studies. This should lead to a better knowledge on the significancy and spreading of MRSA in the hospitals.

Incidence des fractures du fémur proximal dans le canton de Vaud. [Incidence of proximal femoral fractures in the Canton of Vaud].

Hip fractures place a major and increasing burden on health services in Western countries. Reported incidence rates vary considerably from one geographic area to another. No published data are available for Switzerland or surrounding countries, but such descriptive indicators are indispensable in orienting national or regional policies. To fill this gap and to assess the similarity of hip fracture incidence in Switzerland and other countries, we collected data from several sources in 26 public and private hospitals, in the Canton of Vaud (total population: 538,000) for 1986, which allowed us to calculate the incidence (for people over twenty years old) and assess related parameters. 577 hip fractures were identified among the resident population, indicating a crude average annual incidence rate of 140 per 100,000 (95% confidence interval: 128, 152). Corresponding rates for males and females were 58 (47, 68) and 213 (193, 232). Standardized rates and international comparisons show that Swiss rates are slightly lower than those of most industrial countries. More detailed results of relative risks for various study variables are presented and the pathogenesis of hip fractures is discussed.

Schistosomiasis epidemiology and control: how did we get here and where should we go?

Although a disease of great antiquity, scientific studies of schistosomiasis began only 150 years ago. The complete life-cycle was not described until just before the First World War, making it possible at last to plan proper community control programmes. Inadequate tools prevented their effective implementation until well after the Second World War when new tools became available, thanks to the newly formed World Health Organization. Molluscicides spearheaded control programmes until the late 1970s but were then replaced by the newly developed, safe drugs still used today. Whatever the method used, the initial goal of eradication was, in the light of experience and cost, gradually replaced by less ambitious targets; first to stop transmission and then to reduce morbidity. The most successful programmes combined several methods to minimise reinfection after chemotherapy. Comparisons between different programmes are difficult without using appropriate, standardised diagnostic techniques and the correct epidemiological measurements. Some examples will be presented, mainly from our studies on Schistosoma mansoni in Kenya. Drug resistance on a scale comparable with malaria has not occurred in schistosomiasis but the likely withdrawal of all drugs except praziquantel leaves its control extremely vulnerable to this potential problem. An effective, affordable vaccine for use in endemic countries is unlikely to be ready for at least 5 years, and developing strategies for its use could take a further decade or more, judging from experience with drugs and molluscicides. In the interim, by analogy with malaria, the most cost-effective approach would the use of drugs combined with other methods to stop transmission, including molluscicides. The cost of molluscicides needs to be reduced and fears allayed about their supposedly adverse ecological effects.

Genetic epidemiology of fecal egg excretion during Schistosoma mansoni infection in an endemic area in Minas Gerais, Brazil

There is considerable variation in the level of fecal egg excretion during Schistosoma mansoni infections. Within a single endemic area, the distribution of egg counts is typically overdispersed, with the majority of eggs excreted coming from a minority of residents. The purpose of this study was to quantify the influence of genetic factors on patterns of fecal egg excretion in a rural study sample in Brazil. Individual fecal egg excretions, expressed in eggs per gram of feces, were determined by the Kato-Katz method on stool samples collected on three different days. Detailed genealogic information was gathered at the time of sampling, which allowed assignment of 461 individuals to 14 pedigrees containing between 3 and 422 individuals. Using a maximum likelihood variance decomposition approach, we performed quantitative genetic analyses to determine if genetic factors could partially account for the observed pattern of fecal egg excretion. The quantitative genetic analysis indicated that between 21-37% of the variation in S. mansoni egg counts was attributable to additive genetic factors and that shared environment, as assessed by common household, accounted for a further 12-21% of the observed variation. A maximum likelihood heritability (h²) estimate of 0.44 ± 0.14 (mean ± SE) was found for the 9,604 second- and higher-degree pairwise relationships in the study sample, which is consistent with the upper limit (37%) of the genetic factor determined in the variance decomposition analysis. These analyses point to the significant influence of additive host genes on the pattern of S. mansoni fecal egg excretion in this endemic area.

Identification of Human T-lymphotropic Virus Type I (HTLV-I) Subtypes Using Restrited Fragment Length Polymorphism in a Cohort of Asymptomatic Carriers and Patients with HTLV-I-associated Myelopathy/tropical Spastic Paraparesis from São Paulo, Brazil

Although human T-lymphotropic virus type I (HTLV-I) exhibits high genetic stability, as compared to other RNA viruses and particularly to human immunodeficiency virus (HIV), genotypic subtypes of this human retrovirus have been characterized in isolates from diverse geographical areas. These are currently believed not to be associated with different pathogenetic outcomes of infection. The present study aimed at characterizing genotypic subtypes of viral isolates from 70 HTLV-I-infected individuals from São Paulo, Brazil, including 42 asymptomatic carriers and 28 patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), using restricted fragment length polymorphism (RFLP) analysis of long terminal repeat (LTR) HTLV-I proviral DNA sequences. Peripheral blood mononuclear cell lysates were amplified by nested polymerase chain reaction (PCR) and amplicons submitted to enzymatic digestion using a panel of endonucleases. Among HTLV-I asymptomatic carriers, viral cosmopolitan subtypes A, B, C and E were identified in 73.8%, 7.1%, 7.1% and 12% of tested samples, respectively, whereas among HAM/TSP patients, cosmopolitan A (89.3%), cosmopolitan C (7.1%) and cosmopolitan E (3.6%) subtypes were detected. HTLV-I subtypes were not statistically significant associated with patients' clinical status. We also conclude that RFLP analysis is a suitable tool for descriptive studies on the molecular epidemiology of HTLV-I infections in our environment.

Missed appointments in an adolescent outpatient clinic : descriptive analyses of consultations over eight years ; et, Missed appointments in an outpatient clinic for adolescents, an approache to predict the risk of missing

Rapport de synthèse: Les rendez-vous manqués représentent un problème important, tant du point de vue de la santé des patients que du point de vue économique. Pourtant peu d'études se sont penchées sur le sujet, particulièrement dans une population d'adolescents. Les buts de cette étude étaient de caractériser les adolescents qui sont à risque de manquer ou d'annuler leurs rendez-vous dans une clinique ambulatoire de santé pour adolescents, de comparer les taux des rendez-vous manqués et annulés entre les différents intervenants et d'estimer l'efficacité d'une politique de taxation des rendez-vous manqués non excusés. Finalement, un modèle multi-niveau markovien a été utilisé afin de prédire le risque de manquer un rendez-vous. Ce modèle tient compte du passé de l'adolescent en matière de rendez-vous manqués et d'autres covariables et permet de grouper les individus ayant un comportement semblable. On peut ensuite prédire pour chaque groupe le risque de manquer ou annuler et les covariables influençant significativement ce risque. Entre 1999 et 2006, 32816 rendez-vous fixés pour 3577 patients âgés de 12 à 20 ans ont été analysés. Le taux de rendez-vous manqués était de 11.8%, alors que 10.9% avaient été annulés. Soixante pour cent des patients n'ont pas manqué un seul de leur rendezvous et 14% en ont manqué plus de 25%. Nous avons pu mettre en évidence plusieurs variables associées de manière statistiquement significative avec les taux de rendez-vous manqués et d'annulations (genre, âge, heure, jour de la semaine, intervenant thérapeutique). Le comportement des filles peut être catégorisé en 2 groupes. Le premier groupe inclut les diagnostiques psychiatriques et de trouble du comportement alimentaire, le risque de manquer dans ce groupe étant faible et associé au fait d'avoir précédemment manqué un rendez-vous et au délai du rendez-vous. Les autres diagnostiques chez les filles sont associés à un second groupe qui montre un risque plus élevé de manquer un rendez-vous et qui est associé à l'intervenant, au fait d'avoir précédemment manqué ou annulé le dernier rendez-vous et au délai du rendez-vous. Les garçons ont tous globalement un comportement similaire concernant les rendez-vous manqués. Le diagnostic au sein de ce groupe influence le risque de manquer, tout comme le fait d'avoir précédemment manqué ou annulé un rendez-vous, le délai du rendez-vous et l'âge du patient. L'introduction de la politique de taxation des rendez-vous non excusés n'a pas montré de différence significative des tàux de rendez-vous manqués, cependant cette mesure a permis une augmentation du taux d'annulations. En conclusion, les taux de présence des adolescents à leurs rendez-vous sont dépendants de facteurs divers. Et, même si les adolescents sont une population à risque concernant les rendez-vous manqués, la majorité d'entre eux ne manquent aucun de leurs rendez-vous, ceci étant vrai pour les deux sexes. Etudier les rendez-vous manqués et les adolescents qui sont à risque de rater leur rendez-vous est un pas nécessaire vers le contrôle de ce phénomène. Par ailleurs, les moyens de contrôle concernant les rendez-vous manqués devraient cibler les patients ayant déjà manqué un rendez-vous. La taxation des rendez-vous manqués permet d'augmenter les rendez-vous annulés, ce qui a l'avantage de permettre de fixer un nouveau rendez-vous et, de ce fait, d'améliorer la continuité des soins.

Epidemiology of Chagas disease in Guatemala: infection rate of Triatoma dimidiata, Triatoma nitida and Rhodnius prolixus (Hemiptera, Reduviidae) with Trypanosoma cruzi and Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae)

A five-year domiciliary collection in the 22 departments of Guatemala showed that out of 4,128 triatomines collected, 1,675 were Triatoma dimidiata (Latreille, 1811), 2,344 were Rhodnius prolixus Stal 1859, and only 109 were T. nitida Usinger 1939. The Chagas disease parasite, Trypanosoma cruzi, was found in all three species. Their natural infection rates were similar in the first two species (20.6%; 19.1%) and slightly lower in T. nitida(13.8%). However there was no significant difference in the infection rates in the three species (p = 0.131). T. dimidiata males have higher infection rates than females (p = 0.030), whereas for R. prolixus there is no difference in infection rates between males and females (p = 0.114). The sex ratios for all three species were significantly skewed. More males than females were found inside houses for T. dimidiata (p < 0.0001) and T. nitida (p = 0.011); a different pattern was seen for R. prolixus (p = 0.037) where more females were found. Sex ratio is proposed as an index to show the mobility of T. dimidiata in different populations. T. dimidiata is widely distributed in the country, and is also the main vector in at least ten departments, but R. prolixus with higher vectorial capacity is an important vector in at least two departments.

Molecular epidemiology of human immunodeficiency virus-1 in the state of Ceará, Northeast, Brazil

We analyzed, by env and gag heteroduplex mobility assay, 149 human immunodeficiency virus (HIV-1) positive samples collected in Ceará during the year 2000. The prevalence of subtype B was 81.2% and the prevalence of subtype F and B/F recombinants were both 2.7%. Eight (5.4%) and 12 (8%) out of 149 samples showed indeterminate results in the env and gag analysis respectively. By FokI restriction fragment length polymorphism, 34% of the subtype B samples were identified as the typical Brazilian subtype B.In the present study, we identified HIV-1 subtype F and B/F in Ceará for the first time. Our results contribute to the understanding of HIV in Brazil, and may prove useful for the development of vaccine candidates.

Missed appointments in an adolescent outpatient clinic: descriptive analyses of consultations over 8 years.

Missed appointments represent an important medical and economical issue. Few studies on the subject are reported in the literature, particularly regarding adolescents. Our aim was to characterize missed and cancelled appointments in a multidisciplinary outpatient clinic for adolescents, to assess the effectiveness of a policy aimed at reducing missed appointments by introducing payment for those missed appointments not cancelled in advance, and to compare the rates between staff and resident physicians. A total of 32,816 consultations (representing 35 patients aged 12-20 years, 82.4% females) between 1999 and 200 were analysed. The missed appointment rate was 11.8% whilst another 10.9% were cancellations. Females cancelled more than males (11.3% vs. 8.4%, AOR 1.31, 99% CI 1.08-1.59), but there was no difference for missed appointments (11.6% vs. 12.3%, AOR 0.88, 99% CI 0.61-1.08). April and June to October (vacation months) were associated with more missed appointments. Globally mornings had higher rates of missed appointments than afternoons (13.6% vs. 11.2%, AOR 1.25, 99% CI 1.11-1.40). There was a slight difference in missed appointment rates between staff physicians and residents (10.4%; 11.8%, AOR 1.20, 99% CI 1.08-1.33). Missed appointment rates before and after the new policy on missed appointments were similar (1999-2003: 11.9%; 2004-2006: 11.6%, AOR 0.96, 99% CI 0.83-1.10). Conversely, cancellation rates increased from 8.4% (1999-2003) to 14.5% (2004-2006) (AOR 1.83, 99% CI 1.63-2.05). Attendance rates among adolescents show variations depending on vacation and school hours. Being attentive to these factors could help prevent missed appointments. Although having to pay for missed appointments does not increase attendance, it increases cancellations with the advantage that the appointment can be rescheduled.

Usefulness of Mendelian randomization in observational epidemiology.

Mendelian randomization refers to the random allocation of alleles at the time of gamete formation. In observational epidemiology, this refers to the use of genetic variants to estimate a causal effect between a modifiable risk factor and an outcome of interest. In this review, we recall the principles of a "Mendelian randomization" approach in observational epidemiology, which is based on the technique of instrumental variables; we provide simulations and an example based on real data to demonstrate its implications; we present the results of a systematic search on original articles having used this approach; and we discuss some limitations of this approach in view of what has been found so far.

Epidemiology of tuberculosis in Northern Ireland: Annual surveillance report 2007

This report provides an annual update on the prevalence of tuberculosis in Northern Ireland. It gives a general overview of TB rates and statistics, and looks at both pulmonary and non-pulmonary tuberculosis cases in detail, examining the forms of therapy employed and highlighting any drug resistance. The report also includes a discussion, which considers the specifics of newly diagnosed cases (age, place of birth) and provides some comparative data for the UK and Republic of Ireland.