Modelling the epidemiology of infectious diseases for decision analysis: a primer

The number of economic evaluations related to infectious disease topics has increased over the last 2 decades. However, many such evaluations rely on models that do not take into account unique features of infectious diseases that can affect the estimated value of interventions against them. These include their transmissibility from infected to susceptible individuals, the possibility of acquiring natural immunity following recovery from infection and the uncertainties that arise as a result of their complex natural history and epidemiology. Modellers conducting economic evaluations of infectious disease interventions need to know the main features of different types of infectious disease models, the situations in which they should be applied and the effects of model choices on the cost effectiveness of interventions.     

Travel epidemiology: the Saudi perspective

The Kingdom of Saudi Arabia occupies four-fifths of the Arabian Peninsula, with a land area of 2 million square kilometres. Saudi Arabia holds a unique position in the Islamic world, as the custodian of the two holiest places of Islam, in Mecca and Medina. Annually, some 2 million Muslims from over 140 countries embark on Hajj. This extraordinary en masse migration is a unique forum for the study of travel epidemiology since the Hajj carries various health risks, both communicable and non-communicable, often on a colossal scale. Non-communicable hazards of the Hajj include stampede and motor vehicle trauma, fire-related burn injuries and accidental hand injury during animal slaughter. Communicable hazards in the form of outbreaks of multiple infectious diseases have been reported repeatedly, during and following the Hajj. Meningococcal meningitis, gastroenteritis, hepatitis A, B and C, and various zoonotic diseases comprise some of the possible infectious hazards at the Hajj. Many of these infectious and non-infectious hazards can be avoided or averted by adopting appropriate prophylactic measures. Physicians and health personnel must be aware of these risks to appropriately educate, immunize and prepare these travellers facing the unique epidemiological challenges of Hajj in an effort to minimize untoward effects.Travel epidemiology related to the Hajj is a new and exciting area, which offers valuable insights to the travel specialist. The sheer scale of numbers affords a rare view of migration medicine in action. As data is continually gathered and both national and international policy making is tailored to vital insights gained through travel epidemiology, the Hajj will be continually safeguarded. Practitioners will gain from findings of travel related epidemiological changes in evolution at the Hajj: the impact of vaccinating policies, infection control policies and public health are afforded a real-world laboratory setting at each annual Hajj, allowing us to learn from this unique phenomenon of migration medicine.     

2004至2008年江苏省洪泽县法定传染病疫情分析

目的了解2004至2008年江苏省洪泽县法定传染病的流行特征,为制定针对性防治措施提供依据。方法利用传染病网络直报系统和传染病年报表的数据进行统计及描述性分析。结果2004年至2008年,洪泽县共报告法定传染病3418例。甲类0例,乙类传染病15种共2162例,丙类传染病4种共442例。其中常见、高发的传染病为肺结核占各类传染病的43.15%、病毒性肝炎占各类传染病的24.58%,流行性腮腺炎占各类传染病的14.66%,淋病占各类传染病的3.72%,菌痢占各类传染病的3.42%。结论肺结核、肝炎、流行性腮腺炎、淋病、菌痢为预防控制的重点。     

Hepatitis B surface antigen in notified cases of viral hepatitis.

Eighty-five patients notified to the local medical officer of health as infectious or serum hepatitis during the period 1 September 1974-1 September 1975 were investigated by questionnaire. Serum from 73 cases was tested for the presence of HBsAg. Sixteen cases were notified as serum hepatitis but only 13 were shown to have HBsAg in their serum. Sixty-eight cases were notified as infectious hepatitis and 21 HBsAg positive cases were found amongst the 57 sera tested. Two-thirds of the HBsAg positive cases were not suspected clinically. The epidemiology of hepatitis in Christchurch is discussed and suggestion is made that all notified cases of hepatitis should have blood tested for HBsAg.     

Molecular epidemiology and evolution of emerging infectious diseases.

Molecular epidemiology is an emerging science. The development of new and rapid protocols to isolate and identify pathogens, coupled with the sophisticated phylogenetic analysis of their gene sequences, is providing a new and fascinating insight into the biology, origin and spread of infectious diseases. In this essay, I describe some of the ways in which the techniques of modern molecular biology and evolution have equipped us to face the challenge of these new infections.     

Key references in infectious diseases pharmacotherapy

Most health care practitioners are challenged to maintain knowledge of contemporary practice issues in many therapeutic disciplines. Like many other areas, infectious diseases pharmacotherapy continues to evolve because of new information regarding disease epidemiology and new treatment options. Emerging infections and resistance further compound the need for information. To assist clinicians in identifying such important new information, we compiled a list of key references on infectious diseases pharmacotherapy published over the last 2 years.     

Infectious diseases and drug abuse : Prevention and treatment in the drug abuse treatment system

Several communicable infectious Diseases, including AIDS, hepatitis B infection, gonorrhea, syphilis, and tuberculosis, are increasing among drug abusers. Drug abuse treatment programs may be ideal sites to identify those infections and initiate and maintain appropriate medical management. This paper reviews the epidemiology of those infections among drug abusers in the USA, presents rudimentary aspects of medical management of selected infectious diseases, and discusses the need to integrate infectious diseases, drug abuse treatment, and public health approaches if we are to reverse, or at least stabilize, the trends of those diseases.     

An update on human bartonelloses

The data available on Bartonella species has increased rapidly in the last decade with 12 new species and subspecies being described and bartonellas being found to be associated with an increasing spectrum of clinical syndromes in immunocompetent and immunocompromised patients. In addition B. weissii is found in cats. This rapid expansion of knowledge has come about with the development of new culture and molecular biology techniques to isolate and identify the organisms. Much of the information on the bartonellas and the emerging infectious diseases they cause has been derived from the USA and Europe although there is growing evidence that the organisms may be important pathogens in other regions including southern Africa. In this review we describe the bacteriology, epidemiology, clinical and laboratory signs, diagnosis and treatment of bartonella infections and the most recent data on bartonellas in southern Africa.     

GI Epidemiology: infection epidemiology and acute gastrointestinal infections

BACKGROUND: Gastrointestinal infection is a major cause of morbidity and mortality worldwide. The World Health Organisation estimated that in 2001 diarrheal disease was the third most common cause of mortality from infectious diseases worldwide, accounting for some 1.9 million deaths. Gastrointestinal infection is also linked to chronic diseases, for example Helicobacter pylori infection and gastric cancer. AIM: To introduce the features of infection epidemiology that differentiates it from disease epidemiology in general. CONCLUSION: The epidemiologic study of infection is essential for disease control. Infection epidemiology requires consideration of micro-organisms (the infection process and transmission pathways) as well as the host (clinical presentation, behavior and immune status). Although infection epidemiologists often draw on methods used in chronic disease epidemiology there are some special features of infection epidemiology that require additional investigative approaches. We have highlighted these unique features and described some of the special methods available to track infection to its source. Key Points: * The epidemiologic approach to the investigation of gastrointestinal infection is influenced by the interaction between micro-organisms and the host. * The infection epidemiologist can draw on "standard" epidemiologic techniques and on special methods. * Collaboration with microbiologists is essential for studying infection epidemiology. The purpose of this chapter is to introduce the features of infection epidemiology that differentiate it from disease epidemiology in general. Epidemiologic concepts covered in other chapters will not be repeated here, but readers should bear in mind that those methods are also available to use in the study of infection.     

Highlights from the 13th European Congress of Clinical Microbiology and Infectious Diseases in Glasgow,Scotland, May 10-13, 2003. The complex world of infectious diseases

At the 13th European Congress of Clinical Microbiology and Infectious Diseases, held in Glasgow, Scotland, May 10-13, 2003, the latest developments in clinical microbiology and the treatment of infectious diseases were presented alongside recent progress on molecular aspects of diagnosis and emerging patterns of infection. Around 5,000 delegates from more than 80 countries attended the congress, which saw the presentation of more than 400 oral communications and 1,700 posters. In addition to a historical session looking at Scotland's own contribution to the control of infectious diseases, the meeting involved up to six parallel sessions a day, looking at all the major aspects of infectious diseases, treatment, surveillance, epidemiology and drug pharmacodynamics and pharmacokinetics. The organizers also organized a Late Breaker symposium on severe acute respiratory syndrome. The topics likely to be of most interest to Drug News and Perspectives readers are described here.     

Trends in post-operative infections by Gram-positive bacteria

Surgical patients are now more prone than ever to have a post-operative infection. On average, they are now older and more have chronic disease histories with reduced immunocompetence or iatrogenic immunosuppression, and many undergo more aggressive, more complex surgical procedures. Moreover, the infectious agents have changed. A comparison of data collected by the SENTRY Antimicrobial Surveillance Program for the years 1988 and 1998 from North and Latin America and Europe shows important shifts in the nature of the infectious agents. Among the Gram-positive agents, Staphylococcus aureus was the most frequent isolate in both years, but its share has more than doubled. Beta-hemolytic streptococci increased their share from 3 to 5% while enterococci fell from 13 to 8%. Perhaps more important than the shifts in incidence are dramatic changes in the antimicrobial resistance patterns of these agents. Data from the past several years show increasing resistance for the drugs that were previously considered 'first line' treatment for post-surgical infections. The majority of S. aureus and coagulase-negative staphylococci are now resistant to most classes of antibiotics. Antimicrobial resistance is beginning to be detected in beta-hemolytic streptococci, and vancomycin-resistant enterococci, which were not even reported in 1987-1988, now represent 17% of all enterococci isolated in the USA and Canada. To stay ahead in the fight against surgical infections, we must react in a combination of ways, using disinfection, prophylaxis, new antibiotics and, above all, we must practice superb hospital infection control and world-wide antimicrobial epidemiology studies.     

Epidemiology and the concept of causation in multifactorial diseases

Unlike infectious diseases of the past, diseases prevalent in modern industrialized societies have multifactorial origins whose complexity so far has defied an integrated scientific understanding. Their epidemiologic investigation suffers from the conceptual inability of formulating plausible causal hypotheses that mimic a complex reality, and from the practical difficulties of running elaborate studies controlled for multifactorial confounders. Until biomedical research provides a satisfactory understanding of the complex mechanistic determinants of such diseases, epidemiology can only field reductionist causal hypotheses, leading to results of uncertain significance. Consensual but rationally weak criteria devised to extract inferences of causality from such results confirm the generic inadequacy of epidemiology in this area, and are unable to provide definitive scientific support to the perceived mandate for public health action.     

桃源县2005—2013年突发公共卫生事件流行病学分析

目的 分析桃源县2005-2013年突发公共卫生事件流行病学特征,为预防和控制突发公共卫生事件提供科学依据.方法 根据中国疾病预防控制信息系统中的《突发公共卫生事件报告管理信息系统》报告的突发公共卫生事件资料,用描述性流行病统计分析方法.结果 2005-2013年桃源县共报告突发公共卫生事件16起,发病568例,1例死亡病例.以传染病疫情为主,占75％,3月、9月是高发期,中、小学校是高发场所.结论 预防传染病和加强食品卫生监管是桃源县今后应急工作的重点.     

Commensals upon us

A battle to control and curtail bacterial infectious diseases is being waged in our hospitals and communities through antibiotic therapies and vaccines targeting specific species. But what effects do these interventions have on the epidemiology of infections caused by the organisms that are part of our natural microbial flora? Gram-positive and gram-negative bacteria appear as new disease agents from among commensal flora. These include vancomycin resistant enterococci (VRE), community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), non-vaccine invasive serotypes of Streptococcus pneumoniae, new strains of non-type b Haemophilus influenzae and multi-drug resistant Escherichia coli. These examples illustrate how clinical improvements and widespread use and misuse of antibiotics have pushed evolution, allowing normally non-pathogenic strains to become infectious disease threats to human health.     

Molecular epidemiology of antibiotic resistance

Molecular typing methods based on the analysis of the genetic structure of bacteria, are used to address many different problems such as the study of genomic organisation and evolution, the identification of patterns of infection, the identification of sources of transmission, the epidemiological surveillance of infectious diseases and for investigations into outbreaks. Of particular interest is the application of these techniques for acquiring information on the spread of micro-organisms that have become resistant to many clinically important antibiotics. The emergence of antibiotic resistance is one of the most dangerous phenomena of the last 20 years and knowledge of the mechanisms of resistant-gene exchange means fully understanding their spread into all environments. Studies on the molecular epidemiology of antibiotic-resistance in micro-organisms should make it easier to distinguish clonality with respect to horizontal transfer of the determinants of resistance.     

1854年的伦敦霍乱与传染病学之父——约翰·斯诺

19世纪初至20世纪末,霍乱4次出现于英国,传播速度快,患者死亡率高。1854年,约翰·斯诺(John     

1854年的伦敦霍乱与传染病学之父——约翰·斯诺

19世纪初至20世纪末,霍乱4次出现于英国,传播速度快,患者死亡率高。1854年,约翰·斯诺(John Snow)首次发现霍乱在人体内繁殖并通过受污染的水传播。在其霍乱研究进程中,他将霍乱病例放置在地理网格上以及根据家庭供水来源比较霍乱发病率,这方面的独创性构成了传染病学方法发展的突破性创新。毫无疑问,斯诺为现代传染性疾病的微生物理论做出了重要贡献。本文将具体阐述1854年的伦敦霍乱发展进程以及传染病学之父斯诺对于传染病学建立的重要影响,并对霍乱弧菌的生态循环和致病机制进行阐述。     

Antifungal Prophylaxis to Prevent Invasive Mycoses Among Bone Marrow Transplantation Recipients

We reviewed the effect of systemic, intranasal, and lipid formulations of amphotericin B, fluconazole, itraconazole for antifungal prophylaxis. Specifically we reviewed the effect of antifungal prophylaxis on the development of fungal colonization, frequency of superficial and invasive mycosis, and overall mortality and that due to invasive mycoses in bone marrow transplantation recipients. A MEDLINE search was conducted to identify literature describing the risk factors, epidemiology, and chemoprophylaxis of invasive mycosis in these patients. Preliminary data published as abstracts at national infectious diseases and hematology conferences within the last 5 years were included. Antifungal prophylaxis reduces fungal colonization and superficial infection. The ability of antifungal prophylaxis to prevent systemic infection or reduce the need for empiric amphotericin B depends on specific variables. Ultimately, antifungal prophylaxis has no affect on overall mortality, and very little impact on mortality attributed to fungi.     

Is syphilis resurgent in New Zealand in the 21st century? A case series of infectious syphilis presenting to the Auckland Sexual Health Service

Bacterial sexually transmitted infections such as chlamydia and gonorrhoea have been on the rise in recent years in New Zealand. Infectious syphilis has however remained rare over the last few decades, except in New Zealanders who have had sex overseas or in recent immigrants. However, in the previous 2 and a half years (1/2002-9/2004), the number of people presenting to Auckland Sexual Health Service with infectious syphilis has more than doubled. The main people at risk for acquiring infectious syphilis appear to be either men who have sex with men, or heterosexuals who have recently had sex overseas. More information is urgently required about the epidemiology of syphilis in New Zealand. One expedient way to determine whether we have an emerging epidemic would be to make syphilis a notifiable condition.     

Genetic susceptibility to infectious diseases

The clinical outcome of infectious disease (ID) is determined by a complex interaction between microorganism, host genetic factors and environment.

Epidemiological studies have revealed differences within and between populations exposed to the same infectious agent, and in the prevalence or severity of the disease, underlying the relevance of the genetic background. Population genetic studies have estimated the genetic component (susceptibility) in the ID determination and have identified some susceptibility gene(s)/polymorphism(s).

This paper describes the methods used in genetic epidemiology. Complex segregation analysis is used to define genetic models. Parametric linkage analysis and association studies are used to identify polymorphisms strongly linked to the disease. Genome-wide scan and microarray technology are used to map and identify major genes for ID. Future developments will identify subgroups of subjects at different risks of developing ID