Lowbury Lecture. Listeriosis: epidemiology, virulence and the significance of contaminated foodstuffs.

Recent epidemiological evidence confirms that sporadic, as well as outbreak-associated, cases of listeriosis are primarily foodborne in origin. Implicated foodstuffs include meat products, dairy products, fruit, seafood and raw and processed vegetables. Large community-acquired outbreaks in North America and Europe have been complemented by smaller outbreaks involving hospitalized patients. Anecdotal reports and case clusters of nosocomial cases also support foodborne transmission. Cross-infection may be a major mode of transmission as demonstrated in a recent outbreak in Costa Rica. The sporadic nature of outbreaks of listeriosis are more consistent with changes in organism virulence rather than host susceptibility. The population of patients at risk for listeriosis (pregnant women and immunocompromised hosts) may not vary greatly. Establishment of infection is probably dose-dependent and gastric acidity may be protective. However, other organism-specific virulence factors, such as haemolysin production, may affect the post-intestinal phase of infection. Virulence factors other than haemolysins have not been characterized as yet. In summary, acquisition of Listeria monocytogenes infection from the environment by susceptible hosts may be widespread but invasive infection remains rare and the determinants of invasion require further elucidation.     

Nitrite inhalants: history, epidemiology, and possible links to AIDS.

Nitrite inhalants have been commonly abused substances in the United States. Nitrite inhalants and AIDS was a popular topic in the early 1980s, when the cause of AIDS was not known. With the discovery of HIV, concern about nitrite use in the USA waned. However, nitrite inhalant use is associated with behavioral relapse and HIV transmission among gay men, with decreased lymphocyte counts and natural killer cell activity in a few laboratory studies, and it remains a candidate cofactor in the pathogenesis of AIDS-related Kaposi's sarcoma. Discouraging nitrite use continues to be a worthwhile public health goal.     

Social epidemiology: Definition,history, and research examples

Social epidemiology is a branch of epidemiology that focuses particularly on the effects of social-structural factors on states of health. Social epidemiology assumes that the distribution of advantages and disadvantages in a society reflects the distribution of health and disease. It proposes to identify societal characteristics that affect the pattern of disease and health distribution in a society and to understand its mechanisms. The central and initial question of social epidemiology to be answered is what effect do social factors have on individual and population health. However, the new focus on this theme using current epidemiological methods is a relatively recent phenomenon. There are several significant concepts in the field of social epidemiology: 1) the bio-psychosocial paradigm, 2) the population perspective, 3) use of new statistical approaches such as multilevel analysis, and 4) significance of theory. The relationship between social class and health has been a major research field since the beginning of public health history. Many studies have identified the disparities in health among social classes and developed several theories, such as social selection theory and socio-biological translation theory. However, despite the long history of this research field, the effect of social class on health is not yet fully understood. Income distribution and health is a relatively new field within social epidemiology. Three possible mechanisms for the consequences of income distribution on health are 1) disinvestment of human capital, 2) disinvestment of social capital, and 3) psychological process. Refining theories of income distribution is a major challenge in research on income distribution.     

Perspectives on the past and future of psychiatric epidemiology. The 1981 Rema Lapouse Lecture.

Two generations of epidemiological studies of the true prevalence of mental disorders have been conducted since the turn of the century. The first and smaller in number took place prior to World War II and was characterized by the use of records and key informants to define "cases." The second, utilizing the greatly expanded nomenclatures that followed World War II, were based for the most part on personal interviews with all subjects or samples there of in communities all over the world. In total, more than 80 different communities were studied by more than 60 different investigators or teams of investigators in these first and second generation studies. The legacy from these studies comes in two main parts: the first consists of methodological problems centering on the question of how to conceptualize and measure mental disorders independently of treatment status; the second is a set of consistent substantive findings about the amounts of various types of mental disorder, the proportions treated and untreated by members of the mental health professions, and the distribution of the disorders according to gender, rural vs urban location, and social class. Analyses of this legacy from first and second generation studies are presented with a view to developing informed speculations about what might be hoped for in the future, vastly different, third generation of studies in this field.     

戊型肝炎流行病学及治疗进展

戊型肝炎 (hepatitis E)是由戊型肝炎病毒(HEV)引起的急性病毒性肝炎,主要经粪口途径传播,也有经输血传播的报道[1].HEV目前主要有7个基因型(HEV1～7)[2],其中HEV1～4与人类疾病关系最为密切.HEV1和HEV2只感染人,主要流行于卫生条件较差的发展中国家,常因水源被污染而造成大规模流行.发达国家以人畜共患的HEV3和HEV4感染引起的散发病例为主,多由摄入未煮熟的被HEV污染的动物肉类引起[1].     

The checkered history of American psychiatric epidemiology

Context: American psychiatry has been fascinated with statistics ever since the specialty was created in the early nineteenth century. Initially, psychiatrists hoped that statistics would reveal the benefits of institutional care. Nevertheless, their fascination with statistics was far removed from the growing importance of epidemiology generally. The impetus to create an epidemiology of mental disorders came from the emerging social sciences, whose members were concerned with developing a scientific understanding of individual and social behavior and applying it to a series of pressing social problems. Beginning in the 1920s, the interest of psychiatric epidemiologists shifted to the ways that social environments contributed to the development of mental disorders. This emphasis dramatically changed after 1980 when the policy focus of psychiatric epidemiology became the early identification and prevention of mental illness in individuals. Methods: This article reviews the major developments in psychiatric epidemiology over the past century and a half. Findings: The lack of an adequate classification system for mental illness has precluded the field of psychiatric epidemiology from providing causal understandings that could contribute to more adequate policies to remediate psychiatric disorders. Because of this gap, the policy influence of psychiatric epidemiology has stemmed more from institutional and ideological concerns than from knowledge about the causes of mental disorders. Conclusion: Most of the problems that have bedeviled psychiatric epidemiology since its inception remain unresolved. In particular, until epidemiologists develop adequate methods to measure mental illnesses in community populations, the policy contributions of this field will not be fully realized.     

The sixth Carlos E. Rubio Memorial Lecture. Prevention and treatment of variceal hemorrhage

The medical treatment of portal hypertension has experienced a marked progress in the past decade due to the introduction of effective portal hypotensive therapy. This has been possible because of the better understanding of the pathophysiological mechanisms leading to portal hypertension. A major step forward was the introduction of beta-blockers for the prevention of bleeding and rebleeding from gastroesophageal varices. Effective therapy requires the reduction of the hepatic venous pressure gradient (HVPG) to 12 mmHg or below, or at least by 20% of baseline values. Unfortunately, this is only achieved in 1/3 to 1/2 of patients. Combination therapy, associating isosorbide-5-mononitrate and propranolol or nadolol administration enhances the reduction in portal pressure and increases the number of patients in whom HVPG decreases by more than 20% of baseline values and below 12 mmHg. Randomized clinical trials (RCT's) do support the concept that combination therapy is more effective than propranolol or nadolol alone, significantly better than sclerotherapy, and probably than endoscopic banding ligation. Therapy may be complemented by the association of spironolactone. The main inconvenience of pharmacological therapy is that there is no non-invasive method available to detect non-responders to treatment. Failures of drug therapy should be managed endoscopically. Failures of endoscopic treatment require 'rescue' by means of TIPS or shunt surgery. Patients with advanced liver failure should be considered for orthotopic liver transplantation, and put into a waiting list if eligible. In the treatment of acute variceal bleeding pharmacological therapy offer the unique advantage of allowing to provide specific therapy immediately after arrival to hospital, or even during transferral to hospital by ambulance, since it does not require sophisticated equipment and highly qualified medical staff. Vasopressin has been abandoned because of its toxicity, although this can be reduced by the combined administration of transdermal nitroglycerin. Terlipressin has longer effects and is more effective and safer than vasopressin alone or in combination with nitroglycerin. It has proved to be effective and to decrease mortality from bleeding in double-blind studies. RCT's have shown that this drug is as effective and safer than emergency sclerotherapy. Therapy should be maintained for five days to prevent early rebleeding. Somatostatin is probably as effective as terlipressin. Octreotide is probably useful after endoscopic therapy but can not be recommended as first line treatment. Endoscopic injection sclerotherapy and endoscopic banding ligation are very effective, but require well trained medical staff. There is an increasing trend for initiating therapy with a pharmacological agent, followed by semi-emergency endoscopic therapy as soon as a well trained endoscopist is available (within 12-24 hours), while maintaining drug therapy for 5 days. Failures of medical therapy may be treated by a second session of endoscopic treatment, but if this fails TIPS of emergency surgery should be done. In high-risk situations, such as bleeding from gastric varices or in patients with advanced liver failure, the decision for TIPS or surgery should be done earlier, after failure of the initial treatment.