The Epidemiology of Common Communicable Diseases, January 2016

Chart of common communicable disease, stating incubation, transmission, control measures, and public health response produced by Iowa Department of Public Health.

Epidemiologie der chronisch venösen Insuffizienz--Schweizer Befragung liefert überraschende Ergebnisse [Epidemiology of chronic venous insufficiency--Swiss survey with surprising results]

Lower limb chronic venous insufficiency (CVI) is one of the most common diseases in western world adults with considerable socio-economic impact. Varicose veins of the legs are caused by a number of factors. Current data suggest that both lifestyle and environmental factors play a role in varicose vein occurrence. Nevertheless, environmental factors seem to play greater role than previously thought. This was also observed in a Swiss survey of 1099 participants carried out during summer 2008 in 40 different Swiss pharmacies.

The role of vectors in the epidemiology of avian malaria

Studies on host-parasite relationships have commonly reported that parasitized hosts undergo changes in their behavioural and life history traits. How do these changes affect the fitness of the hosts? What are the ecological and evolutionary drivers of these changes? These open questions are crucial to predict the parasite spread amongst hosts. Surprisingly, mosquito vectors of diseases to humans and animals have long been seen as passive parasite transporters, being unaffected by the infection though they also function as hosts. Natural parasite-vector interactions are therefore poorly documented in the literature. In this thesis, we seek to address the role of wild vectors in the epidemiology of avian Plasmodium, the etiological agents of malaria in birds. We first conducted avian malaria surveys in field-caught mosquitoes to identify the natural vectors in our temperate study area. We report that ornithophilic Culex pipiens primarily act as a vector for Plasmodium vaughani in spring, this parasite species being progressively replaced by P. relictum along with the season. Season-related factors may thus shape the mosquitoes' vectorial capacity. We then used experimental approaches to determine the effect of avian malaria on wild, naturally infected C. pipiens. We show that infected mosquitoes incur unavoidable physiological costs associated with parasite exploitation, these costs being expressed as a reduced survival under nutritionally stressed conditions only. These results are of significant importance for the epidemiology of avian malaria since seasonal changes in climate may likely influence food quality and quantity available to the mosquitoes. The host-selection preferences of the vectors with respect to the malaria-infection status of their bird hosts largely determine the disease spreading. In a second laboratory experiment, we thus offered wild C. pipiens the opportunity to choose between uninfected and naturally infected great tits, Parus major. We show that host-seeking mosquitoes have innate orientation preferences for uninfected birds. This suggests that avian malaria parasites exert strong selective pressures on their vectors, pushing them to evolve anti-parasite behaviours. We lastly investigated the links between malaria-associated symptoms in birds and resulting attractiveness to the mosquitoes. We show that experimentally malaria-infected canaries, Serinus canaria, suffer severe haematocrit reduction at peak parasitaemia and reduced basal metabolic rate later in the course of the infection. However, no links between infection and bird attractiveness to the mosquitoes were shown in an experiment using canaries as live bait for mosquito trap in the field. These links may have been masked by confounding environmental factors. Using a system where the vectors, parasites and hosts co-occur in sympatry, this thesis illustrates that vectors are not always Plasmodium permissive, which opposes to the traditional view that malaria parasites should have little effect on their vectors. The way that the vectors respond to the parasite threat is largely determined by the environmental conditions. This may have major implications for the epidemiology of avian malaria. - Les études portant sur les relations hôtes-parasites mentionnent souvent que les hôtes parasités subissent des modifications de leurs traits d'histoire de vie ou bien comportementaux. Comment ces changements affectent-ils la valeur sélective des hôtes et celle de leurs parasites ? Quels sont les déterminants de ces modifications ? Ces questions sont d'un grand intérêt en épidémiologie. Pour autant, les moustiques vecteurs de maladies infectieuses ont longtemps été perçus comme de simples transporteurs de parasites, n'étant pas affectés par ces derniers. Cette thèse porte sur le rôle des vecteurs dans l'épidémiologie des Plasmodium aviaires, agents étiologiques de la malaria chez les oiseaux. Dans le but d'identifier les vecteurs naturels de malaria aviaire dans notre zone d'étude, nous avons tout d'abord collecté des moustiques sur le terrain, puis déterminé leur statut infectieux. Nous rapportons que les moustiques Culex pipiens sont principalement impliqués dans la transmission de Plasmodium vaughani au printemps, cette espèce de parasite étant progressivement remplacée par P. relictum au fil de la saison de transmission. Nous avons ensuite conduit une expérience visant à déterminer l'effet de la malaria aviaire sur des C. pipiens sauvages, naturellement infectés. Nous montrons que des coûts sont associés à l'infection pour les moustiques. Ces coûts occasionnent une diminution de la survie des vecteurs seulement lorsque ceux-ci sont privés de ressources nutritionnelles. Des changements saisonniers de climats pourraient affecter la quantité et la qualité des ressources disponibles pour les vecteurs et donc, leur aptitude à transmettre l'infection. Les traits comportementaux des moustiques vecteurs, tels que la recherche et le choix d'un hôte pour se nourrir, sont d'une importance majeure pour la dispersion de la malaria. Pour cela, nous avons offert à des C. pipiens sauvages l'opportunité de choisir simultanément entre une mésange charbonnière (Parus major) saine et une autre naturellement infectée. Nous montrons que les moustiques s'orientent préférentiellement vers des mésanges saines. Les Plasmodium aviaires exerceraient donc de fortes pressions de sélection sur leurs vecteurs, favorisant ainsi l'évolution de comportements d'évitement des parasites. Enfin nous avons cherché à identifier de potentiels liens entre symptômes de l'infection malarique chez les oiseaux et attractivité de ces derniers pour les moustiques. Nous montrons que des canaris (Serinus canaria) expérimentalement infectés sont fortement anémiés au moment du pic infectieux et que leur métabolisme basai diminue plus tard au cours de l'infection. Toutefois, aucun lien entre le statut infectieux et l'attractivité des canaris pour les moustiques n'a pu être montré lors d'une expérience réalisée en nature. Il se peut que ces liens aient été masqués par des facteurs environnementaux confondants. Dans son ensemble, cette thèse illustre que, contrairement aux idées reçues, les vecteurs de malaria aviaire ne sont pas toujours permissifs avec leurs parasites. L'environnement apparaît aussi comme un facteur déterminant dans la réponse des vecteurs face à la menace d'infection malarique. Cela pourrait fortement affecter l'épidémiologie de la malaria aviaire.

Molecular epidemiology of Pseudomonas aeruginosa in intensive care units over a 10-year period (1998-2007).

Pseudomonas aeruginosa is one of the leading nosocomial pathogens in intensive care units (ICUs). The source of this microorganism can be either endogenous or exogenous. The proportion of cases as a result of transmission is still debated, and its elucidation is important for implementing appropriate control measures. To understand the relative importance of exogenous vs. endogenous sources of P. aeruginosa, molecular typing was performed on all available P. aeruginosa isolated from ICU clinical and environmental specimens in 1998, 2000, 2003, 2004 and 2007. Patient samples were classified according to their P. aeruginosa genotypes into three categories: (A) identical to isolate from faucet; (B) identical to at least one other patient sample and not found in faucet; and (C) unique genotype. Cases in categories A and B were considered as possibly exogenous, and cases in category C as possibly endogenous. A mean of 34 cases per 1000 admissions per year were found to be colonized or infected by P. aeruginosa. Higher levels of faucet contamination were correlated with a higher number of cases in category A. The number of cases in category B varied from 1.9 to 20 cases per 1000 admissions. This number exceeded 10/1000 admissions on three occasions and was correlated with an outbreak on one occasion. The number of cases considered as endogenous (category C) was stable and independent of the number of cases in categories A and B. The present study shows that repeated molecular typing can help identify variations in the epidemiology of P. aeruginosa in ICU patients and guide infection control measures.

Epidemiology of foodborne Norovirus outbreaks in Catalonia, Spain

Background: Noroviruses are one of the principal biological agents associated with the consumption of contaminated food. The objective of this study was to analyse the size and epidemiological characteristics of foodborne outbreaks of gastroenteritis in Catalonia, a region in the northeast of Spain. Methods: In all reported outbreaks of gastroenteritis associated with food consumption, faecal samples of persons affected were analysed for bacteria and viruses and selectively for parasites. Study variables included the setting, the number of people exposed, age, sex, clinical signs and hospital admissions. The study was carried out from October 2004 to October 2005. Results: Of the 181 outbreaks reported during the study period, 72 were caused by Salmonella and 30 by norovirus (NoV); the incidence rates were 14.5 and 9.9 per 100,000 person-years, respectively. In 50% of the NoV outbreaks and 27% of the bacterial outbreaks (p = 0.03) the number of persons affected was ≥10; 66.7% of NoV outbreaks occurred in restaurants; no differences in the attack rates were observed according to the etiology. Hospitalizations were more common (p = 0.03) in bacterial outbreaks (8.6%) than in NoV outbreaks (0.15%). Secondary cases accounted for 4% of cases in NoV outbreaks compared with 0.3% of cases in bacterial outbreaks (p < 0.001) Conclusion: Norovirus outbreaks were larger but less frequent than bacterial outbreaks, suggesting that underreporting is greater for NoV outbreaks. Food handlers should receive training on the transmission of infections in diverse situations. Very strict control measures on handwashing and environmental disinfection should be adopted in closed or partially-closed institutions.

The international epidemiology of child sexual abuse: a continuation of Finkelhor

Objective: The purpose of this paper was to compare the prevalence rates of child sexual abuse reported by [Finkelhor, D. (1994). The international epidemiology of child sexual abuse. Child Abuse & Neglect, 18 (5), 409-417] with those found in recent publications in order to confirm the widespread prevalence of child sexual abuse. Methods: Relevant articles about prevalence of child sexual abuse were identified through searches of computerized databases and a handsearch of Child Abuse & Neglect and the Journal of Child Sexual Abuse. Results: Thirty-eight independent articles were identified, corresponding to 39 prevalence studies; these articles report the prevalence of childhood sexual abuse in 21 different countries, ranging from 0 to 53% for women and 0 to 60% for men. Conclusions: Comparison of the present study with that of [Finkelhor, D. (1994). The international epidemiology of child sexual abuse. Child Abuse & Neglect, 18 (5), 409-417] shows a similarity between prevalence distributions; there appears to be a general pattern that remains more or less constant over the years, especially in women. Practice implications: Twelve years after the first revision study about the international prevalence of child sexual abuse, there is still a need for new data about this topic. The present study shows child sexual abuse is still a widespread problem in the society. In this research, carried out on 38 independent studies, there is new data for 21 countries over the world, being especially relevant the results obtained from other countries different from those pertaining toNorth America or Europe. It is important to point out the high prevalence found in most of the countries, so this information could be a new warning to make society and governments aware of this problem and undertake actions to prevent sexual abuse in childhood.

The international epidemiology of child sexual abuse: a continuation of Finkelhor

Objective: The purpose of this paper was to compare the prevalence rates of child sexual abuse reported by [Finkelhor, D. (1994). The international epidemiology of child sexual abuse. Child Abuse & Neglect, 18 (5), 409-417] with those found in recent publications in order to confirm the widespread prevalence of child sexual abuse. Methods: Relevant articles about prevalence of child sexual abuse were identified through searches of computerized databases and a handsearch of Child Abuse & Neglect and the Journal of Child Sexual Abuse. Results: Thirty-eight independent articles were identified, corresponding to 39 prevalence studies; these articles report the prevalence of childhood sexual abuse in 21 different countries, ranging from 0 to 53% for women and 0 to 60% for men. Conclusions: Comparison of the present study with that of [Finkelhor, D. (1994). The international epidemiology of child sexual abuse. Child Abuse & Neglect, 18 (5), 409-417] shows a similarity between prevalence distributions; there appears to be a general pattern that remains more or less constant over the years, especially in women. Practice implications: Twelve years after the first revision study about the international prevalence of child sexual abuse, there is still a need for new data about this topic. The present study shows child sexual abuse is still a widespread problem in the society. In this research, carried out on 38 independent studies, there is new data for 21 countries over the world, being especially relevant the results obtained from other countries different from those pertaining toNorth America or Europe. It is important to point out the high prevalence found in most of the countries, so this information could be a new warning to make society and governments aware of this problem and undertake actions to prevent sexual abuse in childhood.

Antibiotic susceptibility and molecular epidemiology of Panton-Valentine leukocidin-positive meticillin-resistant Staphylococcus aureus: An international survey

The antibiotic susceptibility and molecular epidemiology of Panton-Valentine leukocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA) isolates reported from 17 countries in the Americas, Europe and, Australia-Asia were analysed. Among a total of 3236 non-duplicate isolates, the lowest susceptibility was observed to erythromycin in all regions. Susceptibility to ciprofloxacin showed large variation (25%, 75% and 84% in the Americas, Europe and Australia-Asia, respectively). Two vancomycin-intermediate PVL-positive MRSA isolates were reported, one from Hong Kong and the other from The Netherlands. Resistance to trimethoprim/sulfamethoxazole and linezolid was <1%. Among 1798 MRSA isolates from 13 countries that were tested for the requested 10 non-β-lactam antibiotics, 49.4% were multisusceptible. However, multiresistant isolates (resistant to at least three classes of non-β-lactam antibiotics) were reported from all regions. Sequence type 30 (ST30) was reported worldwide, whereas ST80 and ST93 were exclusive to Europe and Australia, respectively. USA300 and related clones (ST8) are progressively replacing the ST80 clone in several European countries. Eight major clusters were discriminated by multilocus variable-number tandem repeat assay (MLVA), showing a certain geographic specificity. PVL-positive MRSA isolates frequently remain multisusceptible to non-β-lactam agents, but multiresistance is already prevalent in all regions. Surveillance of MRSA susceptibility patterns should be monitored to provide clinicians with the most current information regarding changes in resistance patterns.

Epidemiology of hypospadias in Europe: a registry-based study.

BACKGROUND: Hypospadias is a common congenital malformation. The prevalence of hypospadias has a large geographical variation, and recent studies have reported both increasing and decreasing temporal trends. It is unclear whether hypospadias prevalence is associated with maternal age. AIM: To analyze the prevalence and trends of total hypospadias, isolated hypospadias, hypospadias with multiple congenital anomalies, hypospadias with a known cause, and hypospadias severity subtypes in Europe over a 10-year period and to investigate whether maternal age is associated with hypospadias. METHODS: We included all children with hypospadias born from 2001 to 2010 who were registered in 23 EUROCAT registries. Information on the total number of births and maternal age distribution for the registry population was also provided. We analyzed the total prevalence of hypospadias and relative risks by maternal age. RESULTS: From 2001 to 2010, 10,929 hypospadias cases were registered in 5,871,855 births, yielding a total prevalence of 18.61 per 10,000 births. Prevalence varied considerably between different registries, probably due to differences in ascertainment of hypospadias cases. No significant temporal trends were observed with the exceptions of an increasing trend for anterior and posterior hypospadias and a decreasing trend for unspecified hypospadias. After adjusting for registry effects, maternal age was not significantly associated with hypospadias. CONCLUSIONS: Total hypospadias prevalence was stable in 23 EUROCAT registries from 2001 to 2010 and was not significantly influenced by maternal age.