Evolutionary determinants of genetic variation in susceptibility to infectious diseases in humans

Although genetic variation among humans in their susceptibility to infectious diseases has long been appreciated, little focus has been devoted to identifying patterns in levels of variation in susceptibility to different diseases. Levels of genetic variation in susceptibility associated with 40 human infectious diseases were assessed by a survey of studies on both pedigree-based quantitative variation, as well as studies on different classes of marker alleles. These estimates were correlated with pathogen traits, epidemiological characteristics, and effectiveness of the human immune response. The strongest predictors of levels of genetic variation in susceptibility were disease characteristics negatively associated with immune effectiveness. High levels of genetic variation were associated with diseases with long infectious periods and for which vaccine development attempts have been unsuccessful. These findings are consistent with predictions based on theoretical models incorporating fitness costs associated with the different types of resistance mechanisms. An appreciation of these observed patterns will be a valuable tool in directing future research given that genetic variation in disease susceptibility has large implications for vaccine development and epidemiology.

[Mechanisms of antibiofilm immunity]

The formation of microbial biomembranes complicates clinical course of infectious diseases. The review deals with the problem of interaction between immune system and specific components of microbial biofilms. The immune mechanisms which may destroy biomembranes and damage biomembrane-associated microorganisms are analyzed. The vulnerable spots of immune defense against microbal biomembranes are described. This review also issues future prospects of immune-based control of microbal biomembrane processes.

Many stimuli pull the necrotic trigger, an overview

The lab of Jürg Tschopp was the first to report on the crucial role of receptor-interacting protein kinase 1 (RIPK1) in caspase-independent cell death. Because of this pioneer finding, regulated necrosis and in particular RIPK1/RIPK3 kinase-mediated necrosis, referred to as necroptosis, has become an intensively studied form of regulated cell death. Although necrosis was identified initially as a backup cell death program when apoptosis is blocked, it is now recognized as a cellular defense mechanism against viral infections and as being critically involved in ischemia-reperfusion damage. The observation that RIPK3 ablation rescues embryonic lethality in mice deficient in caspase-8 or Fas-associated-protein-via-a-death-domain demonstrates the crucial role of this apoptotic platform in the negative control of necroptosis during development. Here, we review and discuss commonalities and differences of the increasing list of inducers of regulated necrosis ranging from cytokines, pathogen-associated molecular patterns, to several forms of physicochemical cellular stress. Since the discovery of the crucial role of RIPK1 and RIPK3 in necroptosis, these kinases have become potential therapeutic targets. The availability of new pharmacological inhibitors and transgenic models will allow us to further document the important role of this form of cell death in degenerative, inflammatory and infectious diseases.

Of mice and microflora: considerations for genetically engineered mice

The phenotype of genetically engineered mice is a combination of both genetic and environmental factors that include the microflora of the mouse. The impact a particular microbe has on a mouse reflects the host-microbe interaction within the context of the mouse genotype and environment. Although often considered a confounding variable, many host-microbe interactions have resulted in the generation of novel model systems and characterization of new microbial agents. Microbes associated with overt disease in mice have been the historical focus of the laboratory animal medical and pathology community and literature. The advent of genetic engineering and the complex of mouse models have revealed previously unknown or disregarded agents that now oblige the attention of the biomedical research community. The purpose of this article is to describe and illustrate how phenotypes can be affected by microflora by focusing on the infectious diseases present in genetically engineered mouse (GEM) colonies of our collective institutions and by reviewing important agents that are rarely seen in most research facilities today. The goal is to introduce the concept of the role of microflora on phenotypes and in translational research using GEM models.

Small protein-mediated quorum sensing in a gram-negative bacterium: novel targets for control of infectious disease

Control of Gram-negative bacterial infections of plants and animals remains a major challenge because conventional approaches are often not sufficient to eradicate these infections. One major reason for their persistence seems to be the capability of the bacteria to grow within biofilms that protect them from adverse environmental factors. Quorum sensing (QS) plays an important role in the formation of biofilms. In QS, small molecules serve as signals to recognize bacterial cell population size, leading to changes in expression of specific genes when a signal has accumulated to some threshold concentration. The small protein Ax21 (Activator of XA21-mediated immunity), serves as a QS factor that regulates biofilm formation and virulence in the Gram-negative bacterium, Xanthomonas oryzae pv. oryzae. Knowledge of small protein-mediated QS in Gram-negative bacteria can be used to develop new methods to control persistent Gram-negative infections.

National surveillance capacity of water-related diseases in the WHO European region

Water-related diseases continue to cause a high burden of mortality and morbidity in the countries of the European Region. Parties to the Protocol on Water and Health are committed to the sustainable use of water resources, the provision of safe drinking water and adequate sanitation to all people of the European Region, and to the reduction of the burden of water-related diseases. A specialized Task Force is implementing a work plan aimed at strengthening the capacity for water-related disease surveillance, outbreak detection and contingency planning. Parties to the Protocol are obliged to set targets, and report on progress on water-related disease surveillance. The present paper aims to provide a baseline assessment of national capacities for water-related disease surveillance on the basis of the replies to a questionnaire. This was prepared in English and Russian and administered to 53 countries, 15 of which replied. The results confirm the heterogeneity in surveillance systems, the weakness of many countries to adequately survey emerging water-related diseases, and the need for specific remedial action. The findings of the exercise will form the basis for future action under the Protocol on Water and Health.

QMRAspot: a tool for Quantitative Microbial Risk Assessment from surface water to potable water

In the Netherlands, a health based target for microbially safe drinking water is set at less than one infection per 10,000 persons per year. For the assessment of the microbial safety of drinking water, Dutch drinking water suppliers must conduct a Quantitative Microbial Risk Assessment (QMRA) at least every three years for the so-called index pathogens enterovirus, Campylobacter, Cryptosporidium and Giardia. In order to collect raw data in the proper format and to automate the process of QMRA, an interactive user-friendly computational tool, QMRAspot, was developed to analyze and conduct QMRA for drinking water produced from surface water. This paper gives a description of the raw data requirements for QMRA as well as a functional description of the tool. No extensive prior knowledge about QMRA modeling is required by the user, because QMRAspot provides guidance to the user on the quantity, type and format of raw data and performs a complete analysis of the raw data to yield a risk outcome for drinking water consumption that can be compared with other production locations, a legislative standard or an acceptable health based target. The uniform approach promotes proper collection and usage of raw data and, warrants quality of the risk assessment as well as enhances efficiency, i.e., less time is required. QMRAspot may facilitate QMRA for drinking water suppliers worldwide. The tool aids policy makers and other involved parties in formulating mitigation strategies, and prioritization and evaluation of effective preventive measures as integral part of water safety plans.

Communicable diseases prioritized for surveillance and epidemiological research: results of a standardized prioritization procedure in Germany, 2011

Introduction

To establish strategic priorities for the German national public health institute (RKI) and guide the institute's mid-term strategic decisions, we prioritized infectious pathogens in accordance with their importance for national surveillance and epidemiological research.

Methods

We used the Delphi process with internal (RKI) and external experts and a metric-consensus approach to score pathogens according to ten three-tiered criteria. Additional experts were invited to weight each criterion, leading to the calculation of a median weight by which each score was multiplied. We ranked the pathogens according to the total weighted score and divided them into four priority groups.

Results

127 pathogens were scored. Eighty-six experts participated in the weighting; “Case fatality rate” was rated as the most important criterion. Twenty-six pathogens were ranked in the highest priority group; among those were pathogens with internationally recognised importance (e.g., Human Immunodeficiency Virus, Mycobacterium tuberculosis, Influenza virus, Hepatitis C virus, Neisseria meningitides), pathogens frequently causing large outbreaks (e.g., Campylobacter spp.), and nosocomial pathogens associated with antimicrobial resistance. Other pathogens in the highest priority group included Helicobacter pylori, Respiratory Syncytial Virus, Varicella zoster virus and Hantavirus.

Discussion

While several pathogens from the highest priority group already have a high profile in national and international health policy documents, high scores for other pathogens (e.g., Helicobacter pylori, Respiratory syncytial virus or Hantavirus) indicate a possible under-recognised importance within the current German public health framework. A process to strengthen respective surveillance systems and research has been started. The prioritization methodology has worked well; its modular structure makes it potentially useful for other settings.

[Consider the advantages and disadvantages of microbial examinations in a hospital, and ideal microbial laboratory]

The main benefit of carrying out microbial examinations in a hospital is that it rapidly yields information on infectious diseases. Microbiology technicians can easily communicate with the physicians and can carry out precise analyses. The disadvantages are the high costs of microbiological examinations, and the need for long training times for microbial laboratory technicians because of the highly technical nature of their duties. In-hospital microbial inspections will lead to: 1)improved rapid diagnostic tests for infectious diseases and evaluation of antibiotic treatment in the early stages of disease; 2) detection of the precise origin of microbes and confirmation of etiological factors; 3) antibiotic susceptibility testing and evaluation of combined effects of antibiotics against multiple drug-resistant bacteria; and 4)genetic analysis and epidemiological statistical analysis for the purpose of infection control in a hospital and surrounding areas.

Tracing personalized health curves during infections

By concentrating on the relationship between health and microbe number over the course of infections, most pathogenic and mutualistic infections can be summarized by a small alphabet of curves, which has implications not only for basic research but for how we might treat patients.

It is difficult to describe host–microbe interactions in a manner that deals well with both pathogens and mutualists. Perhaps a way can be found using an ecological definition of tolerance, where tolerance is defined as the dose response curve of health versus parasite load. To plot tolerance, individual infections are summarized by reporting the maximum parasite load and the minimum health for a population of infected individuals and the slope of the resulting curve defines the tolerance of the population. We can borrow this method of plotting health versus microbe load in a population and make it apply to individuals; instead of plotting just one point that summarizes an infection in an individual, we can plot the values at many time points over the course of an infection for one individual. This produces curves that trace the course of an infection through phase space rather than over a more typical timeline. These curves highlight relationships like recovery and point out bifurcations that are difficult to visualize with standard plotting techniques. Only nine archetypical curves are needed to describe most pathogenic and mutualistic host–microbe interactions. The technique holds promise as both a qualitative and quantitative approach to dissect host–microbe interactions of all kinds.

[Biodiversity and evolution of circulating bacteria and virus populations. Novel problems of medical microbiology]

Biodiversity and evolution of circulating bacteria and virus populations is a serious scientific problem, solving this problem is necessary for effective prophylaxis of infectious diseases. Principal trends of development in this field of science are described. Results of studies that were carried out and investigated biodiversity of principal pathogens in Russia and St. Petersburg in particular are presented. Risk of infectious security of society caused by increasing diversity of pathogenic microorganisms is described, and priority trends of research development in this field are specified.

Statistical inference for multi-pathogen systems

There is growing interest in understanding the nature and consequences of interactions among infectious agents. Pathogen interactions can be operational at different scales, either within a co-infected host or in host populations where they co-circulate, and can be either cooperative or competitive. The detection of interactions among pathogens has typically involved the study of synchrony in the oscillations of the protagonists, but as we show here, phase association provides an unreliable dynamical fingerprint for this task. We assess the capacity of a likelihood-based inference framework to accurately detect and quantify the presence and nature of pathogen interactions on the basis of realistic amounts and kinds of simulated data. We show that when epidemiological and demographic processes are well understood, noisy time series data can contain sufficient information to allow correct inference of interactions in multi-pathogen systems. The inference power is dependent on the strength and time-course of the underlying mechanism: stronger and longer-lasting interactions are more easily and more precisely quantified. We examine the limitations of our approach to stochastic temporal variation, under-reporting, and over-aggregation of data. We propose that likelihood shows promise as a basis for detection and quantification of the effects of pathogen interactions and the determination of their (competitive or cooperative) nature on the basis of population-level time-series data.

It is becoming increasingly evident that pathogens associated with infectious diseases interact amongst themselves. Pathogen interactions can occur in a co-infected host, or in host populations where they co-circulate, and they can be cooperative or competitive. Four serotypes of dengue virus, for example, can exhibit both forms of interactions – cross protection for a temporary period and followed by long-lasting enhancement. This bears important consequences for understanding the ecology and developing control and prevention measures. Detecting such interactions in a natural host population, though, can be tricky. We show that studying the phase relation of epidemic cycles, as it has been typically done, is unreliable. We assess the ability of a likelihood based method in detecting such interactions, and find that they are accurate and robust. We propose that this framework shows promise of serving as a basis for detecting and quantifying pathogen interactions.

Single nucleotide polymorphisms in collagenous lectins and other innate immune genes in pigs with common infectious diseases

Innate immune recognition of pathogens involves various surface receptors and soluble proteins that precede agglutination, complement activation, phagocytosis, and the adaptive immune response. Mannan-binding lectins (MBLs), ficolins (FCNs) and surfactant protein A (SP-A) are soluble collagenous lectins that bind surface structures of various bacteria, viruses and fungi. Some single nucleotide polymorphisms (SNPs) in collagenous lectin genes of humans and other species, including pigs, have been implicated in variation in susceptibility to infectious and inflammatory diseases. In this study we determined the frequencies of 13 SNP alleles of MBL-A, MBL-C, ficolin-α, ficolin-β, and SP-A in 1324 healthy pigs and 461 pigs diagnosed with common infectious diseases at necropsy. For comparison, we also analyzed 12 other SNP alleles in several other innate immune genes, including galectins and TLRs. Several SNPs within genes encoding porcine MBL-A, MBL-C and SP-A were more frequent in pigs diagnosed at necropsy with various diseases or pathogens. These findings suggest that several collagenous lectin SNPs are associated with disease susceptibility and therefore might be genetic markers of impaired innate immune function.

Koch's postulates, carnivorous cows, and tuberculosis today

With Koch's announcement in 1882 of his work with the tubercle bacillus, his famous postulates launched the rational world of infectious disease and an abrupt social change--strict patient isolation. The postulates, so successful at their inception, soon began to show some problems, particularly with cholera, which clearly violated some of Koch's requirements. Subsequent studies of other diseases and the discovery of entirely new ones have so altered and expanded the original postulates that they now are little but a precious touch of history. The present additions and replacements of the original concepts are skillful changes that several authors have devised to introduce new order into understanding complex viral and prion diseases. In 1988, this knowledge, with the totally rational response of the British population and its cattle industry, was critical in promptly blocking the threatened epidemic of human prion disease. In contrast, the recent upsurge of tuberculosis (TB) in the worldwide AIDS epidemic in developing countries, and the sudden increase in metabolic syndrome in wealthy ones, suggests the need for focused sociobiologic research seeking ways to affect the damaging lifestyle behavior of many less educated populations in both settings. The world awaits an equivalent of Koch's Postulates in sociobiology to explain and possibly avert large self-destructive behaviors.

A review of infectious gill disease in marine salmonid fish

Infectious gill diseases of marine salmonid fish present a significant challenge in salmon-farming regions. Infectious syndromes or disease conditions affecting marine-farmed salmonids include amoebic gill disease (AGD), proliferative gill inflammation (PGI) and tenacibaculosis. Pathogens involved include parasites, such as Neoparamoeba perurans, bacteria, such as Piscichlamydia salmonis and Tenacibaculum maritimum, and viruses, such as the Atlantic salmon paramyxovirus (ASPV). The present level of understanding of these is reviewed with regard to risk factors, potential impacting factors, methods of best practice to mitigate infectious gill disease, as well as knowledge gaps and avenues for future research.

A simplified method of performance indicators development for epidemiological surveillance networks--application to the RESAPATH surveillance network

BACKGROUND

Develop and calculate performance indicators allows to continuously follow the operation of an epidemiological surveillance network. This is an internal evaluation method, implemented by the coordinators in collaboration with all the actors of the network. Its purpose is to detect weak points in order to optimize management. A method for the development of performance indicators of epidemiological surveillance networks was developed in 2004 and was applied to several networks. Its implementation requires a thorough description of the network environment and all its activities to define priority indicators. Since this method is considered to be complex, our objective consisted in developing a simplified approach and applying it to an epidemiological surveillance network.

METHODS

We applied the initial method to a theoretical network model to obtain a list of generic indicators that can be adapted to any surveillance network.

RESULTS

We obtained a list of 25 generic performance indicators, intended to be reformulated and described according to the specificities of each network. It was used to develop performance indicators for RESAPATH, an epidemiological surveillance network of antimicrobial resistance in pathogenic bacteria of animal origin in France.

CONCLUSION

This application allowed us to validate the simplified method, its value in terms of practical implementation, and its level of user acceptance. Its ease of use and speed of application compared to the initial method argue in favor of its use on broader scale.

Effect of pneumococcal conjugate vaccination on serotype-specific carriage and invasive disease in England: a cross-sectional study

BACKGROUND

We investigated the effect of the 7-valent pneumococcal conjugate vaccine (PCV7) programme in England on serotype-specific carriage and invasive disease to help understand its role in serotype replacement and predict the impact of higher valency vaccines.

METHODS AND FINDINGS

Nasopharyngeal swabs were taken from children <5 y old and family members (n=400) 2 y after introduction of PCV7 into routine immunization programs. Proportions carrying Streptococcus pneumoniae and serotype distribution among carried isolates were compared with a similar population prior to PCV7 introduction. Serotype-specific case carrier ratios (CCRs) were estimated using national data on invasive disease. In vaccinated children and their contacts vaccine-type (VT) carriage decreased, but was offset by an increase in non-VT carriage, with no significant overall change in carriage prevalence, odds ratio 1.06 (95% confidence interval 0.76-1.49). The lower CCRs of the replacing serotypes resulted in a net reduction in invasive disease in children. The additional serotypes covered by higher valency vaccines had low carriage but high disease prevalence. Serotype 11C emerged as predominant in carriage but caused no invasive disease whereas 8, 12F, and 22F emerged in disease but had very low carriage prevalence.

CONCLUSION

Because the additional serotypes included in PCV10/13 have high CCRs but low carriage prevalence, vaccinating against them is likely to significantly reduce invasive disease with less risk of serotype replacement. However, a few serotypes with high CCRs could mitigate the benefits of higher valency vaccines. Assessment of the effect of PCV on carriage as well as invasive disease should be part of enhanced surveillance activities for PCVs. Please see later in the article for the Editors' Summary.

Evidence of multiple virulence subtypes in nosocomial and community-associated MRSA genotypes in companion animals from the upper midwestern and northeastern United States

OBJECTIVE

Not much is known about the zoonotic transmission of methicillin-resistant Staphylococcus aureus (MRSA) in companion animals in the United States. We report the rate of prevalence of S. aureus and MRSA recovered from clinical samples of animals requiring treatment at veterinary clinics throughout the upper midwestern and northeastern United States.

DESIGN

We compared phenotypes, genotypes, and virulence profiles of the MRSA isolates identified in companion animals, such as cats, dogs, horses, and pigs, with typical human nosocomial and community-associated MRSA (CA-MRSA) genotypes to assess implied zoonotic transmission or zooanthroponosis. Five hundred thirty-three coagulase-positive staphylococci (CPS) isolates recovered between 2006 and 2008 from a variety of animal-source samples were screened for S. aureus by S. aureus-specific 16S rDNA primers and were screened for methicillin-resistance. All MRSA isolates were genotyped by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa typing. They were also screened for common staphylococcal enterotoxin and adhesion genes by multiplex and singleplex PCR.

RESULTS

Among the 533 CPS isolates recovered, 66 (12.4%) were determined to be S. aureus and 24 (4.5%) were MRSA. The percent of animals that were positive for S. aureus were as follows: 6.6% (32 of 487) dogs, 39.6% (19 of 48) cats, 83.3% (10 of 12) horses, and 100% of pigs, rabbits, hamsters and rats. Notably, 36.4% of all S. aureus identified were MRSA. Methicillin-resistant S. aureus was present in clinical samples from 12 of 487 dogs (2.5%), 6 of 48 cats (12.5%), 5 of 12 horses (42%), and 1 of 2 pigs (50%). The 24 MRSA isolates resolved into 4 PFGE clones: USA100 (50%), USA300 (16.7%), USA500 (20.8%) and USA800 (12.5%) and 6 sequence types (ST5, ST8, ST105, ST830, and ST986) or 2 clonal complexes, CC5 and CC8. Five major virulence profiles (clusters A to E) were observed in these MRSA isolates. Genotypic and virulence profiles of cats and dogs were more similar to each other than to those of horses. A Panton-Valentine leukocidin positive isolate with ST8:USA300 background was identified in a pig causing skin and soft infection.

CONCLUSION

The presence of human MRSA clones in these animals suggests possible reverse zoonotic transmission. This study reports the first case of a USA300 genotype in a pig. Presence of multiple virulence profiles within a MRSA genotype in these animals suggests the potential of emergence of new MRSA clones by gaining or losing additional virulence genes.

Divide and conquer? Persistence of infectious agents in spatial metapopulations of hosts

Persistence of an infectious agent in a population is an important issue in epidemiology. It is assumed that spatially fragmenting a population of hosts increases the probability of persistence of an infectious agent and that movement of hosts between the patches is vital for that. The influence of migration on persistence is however often studied in mean-field models, whereas in reality the actual distance travelled can be limited and influence the movement dynamics. We use a stochastic model, where within- and between-patch dynamics are coupled and movement is modelled explicitly, to show that explicit consideration of movement distance makes the relation between persistence of infectious agents and the metapopulation structure of its hosts less straightforward than previously thought. We show that the probability of persistence is largest at an intermediate movement distance of the host and that spatially fragmenting a population of hosts is not necessarily beneficial for persistence.

LifeGene--a large prospective population-based study of global relevance

Studying gene-environment interactions requires that the amount and quality of the lifestyle data is comparable to what is available for the corresponding genomic data. Sweden has several crucial prerequisites for comprehensive longitudinal biomedical research, such as the personal identity number, the universally available national health care system, continuously updated population and health registries and a scientifically motivated population. LifeGene builds on these strengths to bridge the gap between basic research and clinical applications with particular attention to populations, through a unique design in a research-friendly setting. LifeGene is designed both as a prospective cohort study and an infrastructure with repeated contacts of study participants approximately every 5 years. Index persons aged 18-45 years old will be recruited and invited to include their household members (partner and any children). A comprehensive questionnaire addressing cutting-edge research questions will be administered through the web with short follow-ups annually. Biosamples and physical measurements will also be collected at baseline, and re-administered every 5 years thereafter. Event-based sampling will be a key feature of LifeGene. The household-based design will give the opportunity to involve young couples prior to and during pregnancy, allowing for the first study of children born into cohort with complete pre-and perinatal data from both the mother and father. Questions and sampling schemes will be tailored to the participants' age and life events. The target of LifeGene is to enroll 500,000 Swedes and follow them longitudinally for at least 20 years.

Infectious agents

The detection and characterization of microbial agents in biological specimens are essential for the investigation of disease outbreaks, for epidemiologic studies of the clinical course of infections, and for the assessment of the role of infectious agents in chronic diseases. Methodological approaches depend on the infectious agent, the specimens analysed and the target populations. Although the diagnosis of infectious diseases has traditionally relied on direct microscopic examination of samples and on the cultivation of microbial agents in vitro, novel techniques with increased sensitivity and specificity are now being used on samples that can be more easily collected and transported to microbiology laboratories (e.g. dried blood spots on filter paper for nucleic acid analysis). Direct detection techniques include the microscopic examination of specimens with special stains, antigen detection and nucleic acid detection by molecular assays. These assays are highly sensitive and provide rapid results for most agents. Genomic amplification assays greatly increase the sensitivity of nucleic acid-based tests by extensive amplification of specific nucleic acid sequences before detection. Real-time polymerase chain reaction (PCR) permits genomic amplification concurrently with detection of amplified products. Typing infectious agents requires additional investigation employing either serologic techniques to identify unique antigenic epitopes, or molecular techniques. These studies are important for epidemiologic purposes, as well as for the investigation of pathogenesis, disease progression, and to establish causality between a disease and a microbial agent. Much of bacteriology has relied on growth of organisms on artificial media, and on identification of bacterial growth with biochemical, serological, or more recently, nucleic acid-based tests. The detection of specific antibodies from the host directed against pathogens is another strategy to identify current or past infections.

[Efficacy of reamberin in treating heavy acute intestinal infection in children]

The current health conditions dictate the need to reduce the time of patient treatment in hospital and require rational use of drugs. Reduction of the duration of intoxication syndrome in severe forms of intestinal infections in children depends on infusion therapy and choice of solutions for intravenous administration. Reamberin is generation IV infusion preparation for intensive care, representing a balanced isotonic detoxicant infusion solution based on succinic acid. Using reamberin ensures a significant decrease in the time of stay in hospital for children with severe forms of intestinal infections, which is achieved by reducing the duration of endogenous intoxication.

Comparison between active and passive surveillance within the network of epidemiological surveillance of animal diseases in Chad

A comparative study between passive and active surveillance based on herd visits (villages) was conducted over a period of 24 months. It included 106 surveillance stations of the animal disease epidemiological surveillance network in Chad distributed randomly into 52 stations of active surveillance and 54 stations of passive surveillance. Nine diseases of various vaccination and expected prevalence status were monitored. The active surveillance stations carried out four herd visits monthly to look for the diseases under surveillance and organised four farmers awareness-raising meetings to stimulate them to make disease notifications. The passive surveillance stations held each month four farmer awareness-raising meetings. The suspicions recorded by the stations were consigned to a suspicion form specific to each disease, indicating whether a call from the farmer, a visit to the herd or a awareness-raising meeting was the source. The results showed that, irrespective of surveillance type, all diseases under surveillance, except the rare diseases (Rinderpest and Rift Valley Fever) were reported by the surveillance agents. However, suspicions recorded following farmer calls are significantly more important than suspicions carried out during herd visits or meetings. Nevertheless, a considerable number of suspicions is recorded during awareness-raising meetings. Finally approximately 83% of the herd visits realised by the active surveillance stations showed negative results (no suspicion identified). Passive surveillance stimulated by awareness-raising meetings appears to be better adapted to Chads conditions and less expensive for the surveillance of existing diseases. However, for the rare diseases, other methods of specific active surveillance (such as for example sentinel herds) remain important to complete passive surveillance.

Interscience Conference on Antimicrobial Agents and Chemotherapy - 50th Annual Meeting - Research on Promising New Agents: Part 2

The 50th annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), held in Boston, included topics covering new therapeutic developments in the field of infectious disease. This conference report highlights selected presentations on research with novel antimicrobial agents. Investigational drugs discussed include the chitin synthase inhibitor nikkomycin Z (Valley Fever Solutions/University of Arizona), the glycosylphosphatidylinositol biosynthesis inhibitor E-1210 (Eisai), the β-1,3-d-glucan synthesis inhibitor MK-3118 (Merck & Co/SCYNEXIS), the metalloenzyme inhibitors VT-1129 and VT-1161 (both Viamet Pharmaceuticals), and the anti-inflammatory nanoemulsion NB-003 (NanoBio).

Infectious disease as aetiological factor in the pathogenesis of systemic sclerosis

Systemic sclerosis is an autoimmune disease characterised by vascular obliteration, excessive extracellular matrix deposition and fibrosis of the connective tissues of the skin, lungs, gastrointestinal tract, heart, and kidneys. The pathogenesis of systemic sclerosis is extremely complex; at present, no single unifying hypothesis explains all aspects. Over the last 20 years increasing evidence has accumulated to implicate infectious agents in the aetiology of systemic sclerosis. Increased antibody titres, a preponderance of specific strains in patients with systemic sclerosis, and evidence of molecular mimicry inducing autoimmune responses suggest mechanisms by which infectious agents may contribute to the development and progression of systemic sclerosis. Here we review the current state of knowledge of infectious risk factors in systemic sclerosis and the possible mechanisms by which infectious exposures might induce pathologic processes.

Interscience Conference on Antimicrobial Agents and Chemotherapy - 50th Annual Meeting - Research on Promising New Agents: Part 1

The 50th annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), held in Boston, included topics covering new therapeutic developments in the field of infectious disease. This conference report highlights selected presentations on research with novel antimicrobial agents. Investigational drugs discussed include the dicationic porphyrin derivative XF-73 (Destiny Pharma), the tetracycline analog TP-434 (Tetraphase Pharmaceuticals), an elongation factor Tu inhibitor (Novartis Institutes for BioMedical Research), the dihydrofolate reductase inhibitor Rx-101005 (Trius Therapeutics), SII RMab, a fully human mAb to rabies glycoprotein (Massachusetts Biologic Laboratories/Serum Institute of India), the oral lipopeptide CB-183315 (Cubist Pharmaceuticals) for the treatment of Clostridium difficile-associated diarrhea, the phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor LMV-601 (Lumavita), and DS-003 (International Partnership for Microbicides), a small-molecule Gp120 inhibitor.

Infection control: the case for horizontal rather than vertical interventional programs

The authors define two types of infection control interventions: horizontal, in which all infections at any site are reduced; and vertical, in which only specific organisms are targeted. We suggest that horizontal programs should form the platform of all infection control programs and the key question should be, what is the incremental value of a new vertical program?

Detection of blood-transmissible agents: can screening be miniaturized?

Transfusion safety relating to blood-transmissible agents is a major public health concern, particularly when faced with the continuing emergence of new infectious agents. These include new viruses appearing alongside other known reemerging viruses (West Nile virus, Chikungunya) as well as new strains of bacteria and parasites (Plasmodium falciparum, Trypanosoma cruzi) and finally pathologic prion protein (variant Creutzfeldt-Jakob disease). Genomic mutations of known viruses (hepatitis B virus, hepatitis C virus, human immunodeficiency virus) can also be at the origin of variants susceptible to escaping detection by diagnostic tests. New technologies that would allow the simultaneous detection of several blood-transmissible agents are now needed for the development and improvement of screening strategies. DNA microarrays have been developed for use in immunohematology laboratories for blood group genotyping. Their application in the detection of infectious agents, however, has been hindered by additional technological hurdles. For instance, the variability among and within genomes of interest complicate target amplification and multiplex analysis. Advances in biosensor technologies based on alternative detection strategies have offered new perspectives on pathogen detection; however, whether they are adaptable to diagnostic applications testing biologic fluids is under debate. Elsewhere, current nanotechnologies now offer new tools to improve the sample preparation, target capture, and detection steps. Second-generation devices combining micro- and nanotechnologies have brought us one step closer to the potential development of innovative and multiplexed approaches applicable to the screening of blood for transmissible agents.

[Focus on health surveillance of health workers exposed to blood-transmissible biological agents: results and perspectives of a multicenter working group]

The biological risk from exposure to bloodborne pathogens in health care environments represents a frequent and widespread risk, involving a large number of exposed workers. On the basis of the available scientific innovations, the recent legislation regarding health and safety of workers and the experiences of SIMLII guidelines on health surveillance (HS) workers exposed to biological risk, a multicenter study was carried out, involving nine relevant hospitals and about 32 000 healthcare workers (HCW). A review of the literature was performed, with particular reference to the last 10 years. For each hospital, protocols of HS have been examined according to tasks and biological risk from bloodborne viruses (HBV, HDV, HCV, HIV) as well as management of HCW infected with this pathogens. Differences of risk management in the hospitals, in relationship also with recommendations of the literature have been evaluated. The literature supplies important indications for HS management of HCW exposed to bloodborne pathogens, with relevant information also for patient safety. Preventive examinations are in line with the recommendations of literature and similar across the hospitals for HCV and HIV, while they are different for HBV. Periodic surveillance was different for the frequency, among the hospitals and also as compared to national SIMLII guidelines. As for management, no differentiation among the hospitals was detected as referred to different risk of exposure, while differences were observed around definitions of restrictions. Finally, good medical practices to support occupational physicians in the prevention and management of HCWs' exposed to biological risks are suggested.

Infections after living donor liver transplantation in children

The aim of this study was to evaluate the infectious complications after living donor liver transplantation (LDLT) in children. We enrolled 95 children (38 boys and 57 girls) who underwent LDLT from 1994 to 2004. The median age was 22 months (range, 6 months to 15 yr). We retrospectively investigated the proven episodes of bacterial, viral, and fungal infection. There occurred 150 infections in 67 (70%) of 95 patients (1.49 infections/patient); 74 in 43 patients were bacterial, 2 in 2 were fungal, and 74 in 42 were viral. The most common sites of bacterial infection were the bloodstream (33%) and abdomen (25%). Most of the bacterial infections occurred within the first month after LDLT. Bacterial and fungal infections did not result in any deaths. The most common causes of viral infection were Epstein-Barr virus in 37 patients and cytomegalovirus in 18. Seven of the 14 deaths after LDLT were associated with viral infection. Our study suggests that infection is one of the important causes of morbidity and mortality after LDLT. Especially careful monitoring and management of viral infections is crucial for improving the outcome of LDLT in children.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: darwinian medicine and the 'hygiene' or 'old friends' hypothesis

The current synthesis of the 'hygiene hypothesis' suggests that the recent increase in chronic inflammatory disorders is at least partly attributable to immunodysregulation resulting from lack of exposure to microorganisms that have evolved an essential role in the establishment of the immune system. This document provides a background for discussion of the following propositions. 1. The essential role of these organisms is an example of 'evolved dependence'. 2. The most relevant organisms are those that co-evolved with mammals, and already accompanied early hominids in the Paleolithic. 3. More recently evolved 'childhood infections' are not likely to have evolved this role, and recent epidemiology supports this contention. 4. This mechanism is interacting with other modern environmental changes that also lead to enhanced inflammatory responses [inappropriate diet, obesity, psychological stress, vitamin D deficiency, pollution (dioxins), etc.]. 5. The range of chronic inflammatory disorders that is affected is potentially larger than usually assumed [allergies, autoimmunity, inflammatory bowel disease, but also vascular disease, some cancers, depression/anxiety (when accompanied by raised inflammatory cytokines), and perhaps neurodegenerative disorders and type 2 diabetes].

A PubMed-wide associational study of infectious diseases

BACKGROUND

Computational discovery is playing an ever-greater role in supporting the processes of knowledge synthesis. A significant proportion of the more than 18 million manuscripts indexed in the PubMed database describe infectious disease syndromes and various infectious agents. This study is the first attempt to integrate online repositories of text-based publications and microbial genome databases in order to explore the dynamics of relationships between pathogens and infectious diseases.

METHODOLOGY/PRINCIPAL FINDINGS

Herein we demonstrate how the knowledge space of infectious diseases can be computationally represented and quantified, and tracked over time. The knowledge space is explored by mapping of the infectious disease literature, looking at dynamics of literature deposition, zooming in from pathogen to genome level and searching for new associations. Syndromic signatures for different pathogens can be created to enable a new and clinically focussed reclassification of the microbial world. Examples of syndrome and pathogen networks illustrate how multilevel network representations of the relationships between infectious syndromes, pathogens and pathogen genomes can illuminate unexpected biological similarities in disease pathogenesis and epidemiology.

CONCLUSIONS/SIGNIFICANCE

This new approach based on text and data mining can support the discovery of previously hidden associations between diseases and microbial pathogens, clinically relevant reclassification of pathogenic microorganisms and accelerate the translational research enterprise.

Towards an ontological representation of resistance: the case of MRSA

This paper addresses a family of issues surrounding the biological phenomenon of resistance and its representation in realist ontologies. The treatments of resistance terms in various existing ontologies are examined and found to be either overly narrow, internally inconsistent, or otherwise problematic. We propose a more coherent characterization of resistance in terms of what we shall call blocking dispositions, which are collections of mutually coordinated dispositions which are of such a sort that they cannot undergo simultaneous realization within a single bearer. A definition of 'protective resistance' is proposed for use in the Infectious Disease Ontology (IDO) and we show how this definition can be used to characterize the antibiotic resistance in Methicillin-Resistant Staphylococcus aureus (MRSA). The ontological relations between entities in our MRSA case study are used alongside a series of logical inference rules to illustrate logical reasoning about resistance. A description logic representation of blocking dispositions is also provided. We demonstrate that our characterization of resistance is sufficiently general to cover two other cases of resistance in the infectious disease domain involving HIV and malaria.

[Prospects for development of immunoprophylaxis up to 2020 - 2030]

Analytic materials on perspectives of immunization up to 2020 - 2030 are presented. Middle-term and long-term prognoses are proposed, perspectives of development of distinct aspects of immunization are considered including increase of number of infections controlled in framework of national immunization schedule, routine immunization of middle-aged and elderly persons, keeping of routine mass vaccination during epidemiological welfare, development and implementation of alternative methods of immunization as well as using new technologies of vaccine manufacturing. It was concluded that to 2020 - 2030 synchronous use of vaccines in national immunization schedules framework will result in elimination of several anthroponoses, decreased incidence of widespread childhood infections down to sporadic cases and significant increase of life-span of patients with chronic diseases.

Model or meal? Farm animal populations as models for infectious diseases of humans

In recent decades, theory addressing the processes that underlie the dynamics of infectious diseases has progressed considerably. Unfortunately, the availability of empirical data to evaluate these theories has not grown at the same pace. Although laboratory animals have been widely used as models at the organism level, they have been less appropriate for addressing issues at the population level. However, farm animal populations can provide empirical models to study infectious diseases at the population level.

[Conflicts and vector-borne diseases]

Based on literature and personal experiences, vector-borne diseases and conflicts are reviewed. Simple rapid diagnostic tests for three important parasitoses are available. Resort is often made to case definitions and to presumptive treatment. Resistance is an emerging problem. Vaccines are still not available for most diseases. Promising preventive methods, including long-lasting impregnated bed-nets and tents, are available. War has been an impetus for disclosing life-cycles of vector-borne diseases and for control methods; peace, reconciliation and poverty reduction are required to achieve lasting control.