Specific Infectious Agents Research Articles

Infections in thalassemia and hemoglobinopathies: focus on therapy-related complications.

The clinical approach to thalassemia and hemoglobinopathies, specifically Sickle Cell Disease (SCD), based on transfusions, iron chelation and bone marrow transplantation has ameliorated their prognosis. Nevertheless, infections still may cause serious complications in these patients. The susceptibility to infections in thalassemia and SCD arises both from a large spectrum of immunological abnormalities and from exposure to specific infectious agents. Four fundamental issues will be focused upon as central causes of immune dysfunction: the diseases themselves; iron overload, transfusion therapy and the role of the spleen. Thalassemia and SCD differ in their pathogenesis and clinical course. It will be outlined how these differences affect immune dysfunction, the risk of infections and the types of most frequent infections in each disease. Moreover, since transfusions are a fundamental tool for treating these patients, their safety is paramount in reducing the risks of infections. In recent years, careful surveillance worldwide and improvements in laboratory tests reduced greatly transfusion transmitted infections, but the problem is not completely resolved. Finally, selected topics will be discussed regarding Parvovirus B19 and transfusion transmitted infections as well as the prevention of infectious risk postsplenectomy or in presence of functional asplenia.

Epidemiology of childhood leukemia in New Zealand: Studies of infectious hypotheses

The etiology of childhood leukemia remains an enigma despite decades of research. Hypotheses of an infectious etiology have been around for a long time, and in the last 20 years there have been two main theoretical contenders. One of these involves the possibility of a specific infectious agent having a causative role, and animal leukemia viruses would be analogous to this. Another theory relates to the possible involvement of unusual patterns of infections in infancy and how they might relate to aberrant immune responses. The first of these is easier to test.In New Zealand, since the early 1990s we have embarked on a program of research on the epidemiology of childhood leukemia. One of the goals has been to test hypotheses about the role of infection in causation. A variety of study designs have been employed, including descriptive, clustering, case-control and contributions to pooled international analyses.Some of the more interesting findings include: there has been a marked increase in the incidence of acute lymphoblastic leukemia among young children in New Zealand since the mid 1960s, poorer families are at greater risk, and there is no clear support for hypotheses of an infectious cause from the New Zealand data. However because of our small total population (4 million people) we cannot produce clear results on our own. Hence our current international collaborations, for example in CLIC (the Childhood Leukemia International Consortium) represent an important step forward. As countries work together across international boundaries we have a renewed hope that the causes of the childhood leukemias will be unlocked in the foreseeable future.

Herd immunity: recent uses in vaccine assessment

Human communities defend themselves against specific infectious agents in a way that extends beyond the simple sum of the immune status of its individuals. By analogy with individual immunity to specific agents, the community level of immunity may vary from complete susceptibility to full protection. Herd immunity has been used to name this community property, which is the result of evolution through natural selection, leading to relationships between two species, typical of prey–predator systems. Varying uses of the term herd immunity led to the use of other expressions, such as herd protection, herd effect and community immunity. Knowledge derived from observational studies and models on herd immunity has supported decisions on the choice of vaccines and vaccination strategies for the benefit of populations. This knowledge is most likely to be extended in the future, with far-reaching effects.

High immunoglobulin A seropositivity for combined Chlamydia pneumoniae, Helicobacter pylori infection, and high-sensitivity C-reactive protein in coronary artery disease patients in India can serve as atherosclerotic marker

Atherosclerosis is increasingly recognized as a chronic inflammatory disease. A variety of infectious agents (Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus [CMV]) and inflammatory marker such as high-sensitivity C-reactive protein (hs-CRP) have been found to be associated with atherosclerosis and its consequences. There is a need to know about the type and burden of infection in coronary artery disease (CAD) patients and the level of hs-CRP in India as there is growing evidence that a variety of pathogens are participating in the development and/or acceleration of at least pre-existing atherosclerosis. In addition, there is a need to find the association between these pathogens and conventional risk factors among CAD patients in India, to possibly identify a prognostic marker. In this study 192 patients with incident or prevalent CAD attending the Cardiology Outpatient Department of Safdarjung Hospital, New Delhi, India, were enrolled. In addition, 192 age-and sex-matched controls were also included. Cases and controls differ significantly in seropositivity to C. pneumoniae immunoglobulin IgA (154 vs 76) and IgG (71 vs 48) (P < 0.001, P < 0.015), H. pylori IgA (98 vs 57) and IgG (77 vs 43) (P < 0.001, P < 0.001), CMV IgG (62 vs 38) (P = 0.01) and with hs-CRP (114 vs 60) (P < 0.001), respectively. The level of hs-CRP was higher in CAD patients with IgA seropositivity of C. pneumoniae and H. pylori (5.18 and.65 mg/l) than the IgG of these bacteria (3.73 and 3.36 mg/l), respectively. These findings support an association between specific infectious agents, namely, C. pneumoniae, H. pylori, CMV, and hs-CRP in CAD patients. Association of hs-CRP with IgA specific for C. pneumoniae and H. pylori suggests the role of chronic infection in the development of CAD and may be used as a marker to target the population.

Patients with abnormal IgM levels: assessment, clinical interpretation, and treatment

INTRODUCTION This review of the role of IgM in cognate immunity is part of a series on ambulatory diagnoses and management of primary immune deficiency diseases edited by Chitra Dinakar, University of Missouri.1 IgM is phylogenetically the earliest antibody class identified and the first immunoglobulin isotype to appear in the circulation after exposure to a new antigen. IgM plays an important role in the ontogeny of B cells and in early cognate immune responses.2 VDJ rearrangement of the immunoglobulin heavy chain occurs at the pre– B-cell stage, when light chains are still of the surrogate type ( 5/VpreB). Further maturation leads to immature B cells, which express surface IgM and IgD and carry and light chains, creating a functional B-cell receptor that allows antigen recognition and further development into unswitched memory B cells (IgM /D , CD27 ). After interaction with the T-cell receptor of antigen-specific CD4 T cells via major histocompatibility complex II and costimulatory molecules (CD40 ligand [CD40L]/CD40, inducible costimulator [ICOS]/ICOS ligand), mature B cells undergo isotype switching, resulting in B cells expressing CD27 and IgG, IgA, or IgE. Whereas IgM is responsible for rapid and early generation of antibody, long-term humoral immunity is initiated by the production of high-affinity IgG or IgA antibody. The demonstration of IgM antibodies to a specific infectious agent can be used as an indicator of recent infection. The presence of IgM in cord blood ( 20 mg/dL) may indicate prenatal infection because IgM antibody cannot be acquired from the mother by transplacental passage. In infants, IgM serum levels increase rapidly from a mean of 11 mg/dL at term to 55 mg/dL at 1 year of age. By 2 years, IgM concentration is approximately 60% of that in adults. IgM is expressed as a monomer on the surface of naive and mature unswitched B cells, where it forms the antigen receptor complex together with the coreceptors Ig and Ig . If secreted, most IgM forms a pentameric complex, which stays mostly (70% to 80%) intravascular. Its half-life is approximately 6 days, in contrast to IgG, which has a half-life of 21 to 28 days. IgM antibodies are uniquely efficient in agglutination and are highly avid because of their multimeric nature and strong complement fixation.

Comparison of two real-time reverse transcription polymerase chain reaction assays for the detection of Equine arteritis virus nucleic acid in equine semen and tissue culture fluid

Two previously developed TaqMan fluorogenic probe-based 1-tube real-time reverse transcription polymerase chain reaction (real-time RT-PCR) assays (T1 and T2) were compared and validated for the detection of Equine arteritis virus (EAV) nucleic acid in equine semen and tissue culture fluid (TCF). The specificity and sensitivity of these 2 molecular-based assays were compared to traditional virus isolation (VI) in cell culture. The T1 real-time RT-PCR had a higher sensitivity (93.4%) than the T2 real-time RT-PCR (42.6%) for detection of EAV RNA in semen. However, the T1 real-time RT-PCR was less sensitive (93.4%) than the World Organization for Animal Health (OIE)-prescribed VI test (gold standard). The sensitivity of both PCR assays was high (100.0% [T1] and 95.2% [T2]) for detecting EAV RNA in TCF. In light of the discrepancy in sensitivity between either real-time RT-PCR assay and VI, semen that is negative for EAV nucleic acid by real-time RT-PCR that is from an EAV-seropositive stallion should be confirmed free of virus by VI. Similarly, the presence of EAV in TCF samples that are VI-positive but real-time RT-PCR-negative should be confirmed in a 1-way neutralization test using anti-EAV equine serum or by fluorescent antibody test using monoclonal antibodies to EAV. If the viral isolate is not identified as EAV, such samples should be tested for other equine viral pathogens. The results of this study underscore the importance of comparative evaluation and validation of real-time RT-PCR assays prior to their recommended use in a diagnostic setting for the detection and identification of specific infectious agents.

Leprosy elimination: not as straightforward as it seemed.

Leprosy is a unique and enigmatic disease. It is one of the few diseases to have been known in ancient and medieval times, and it was one of the first diseases to be linked to a specific infectious agent, Mycobacterium leprae (M. leprae), in 1873. 1 Yet even now, the organism cannot be cultured in vitro, and important gaps persist in our understanding of its biology and epidemiology. 2 In particular, although contact with a known case of leprosy is a major risk factor in contracting the disease, scientists are not certain how the organism is transmitted from one individual to another, nor do they know when, throughout the period of incubation and clinical disease, an individual is particularly infectious.3 These limitations have prevented the development of highly effective leprosy control measures, and there is little evidence that the transmission of the disease has been significantly reduced in recent years, despite efforts made toward that goal.4 As a bacterial infection, leprosy is susceptible to treatment with antibiotics; therefore, much has changed in the management of the disease over the last 50 years.5 The effective treatment of leprosy with chemotherapeutic agents began in the early 1950s with the introduction of dapsone. However, at least 10 years of treatment were required for multibacillary cases, and lifelong treatment was often advised for those individuals with the highest bacillary counts. In the early 1980s, the introduction of multidrug regimens, all of which included the potent bactericidal drug rifampicin, allowed the length of treatment to be cautiously reduced-to a fixed period of 24 months by the early 1990s and to a fixed period of only 12 months by the end of that decade.6 For the individual patient, multidrug therapy (MDT) meant a relatively rapid and effective cure.

Porphyromonas gingivalis Mediated Periodontal Disease and Atherosclerosis:Disparate Diseases with Commonalities in Pathogenesis Through TLRs

Toll-like receptors (TLRs) are a group of pathogen-associated molecular pattern receptors, which play an important role in innate immune signaling in response to microbial infection. It has been demonstrated that TLRs are differentially up regulated in response to microbial infection and chronic inflammatory diseases such as atherosclerosis. Furthermore hyperlipidemic mice deficient in TLR2, TLR4, and MyD88 signaling exhibit diminished inflammatory responses and decreased atherosclerosis. Accumulating evidence has implicated specific infectious agents including the periodontal disease pathogen Porphyromonas gingivalis in the progression of atherosclerosis. Evidence in humans suggesting that periodontal infection predisposes to atherosclerosis is derived from studies demonstrating that the periodontal pathogen P. gingivalis resides in the wall of atherosclerotic vessels and seroepidemiological studies demonstrating an association between pathogen-specific IgG antibodies and atherosclerosis. We have established that the inflammatory signaling pathways that P. gingivalis utilizes is dependent on the cell type and this specificity clearly influences innate immune signaling in the context of local and distant chronic inflammation induced by this pathogen. We have demonstrated that P. gingivalis requires TLR2 to induce oral inflammatory bone lose in mice. Furthermore, we have demonstrated that P. gingivalis infection accelerates atherosclerosis in hyperlipidemic mice with an associated increase in expression of TLR2 and TLR4 in atherosclerotic lesions. Our recent work with P. gingivalis has demonstrated the effectiveness of specific intervention strategies (immunization) in the prevention of pathogen-accelerated atherosclerosis. Improved understanding of the mechanisms driving infection, and chronic inflammation during atherosclerosis may ultimately provide new targets for therapy.

A stochastic simulation model to determine the sample size of repeated national surveys to document freedom from bovine herpesvirus 1 (BoHV-1) infection

BackgroundInternational trade regulations require that countries document their livestock's sanitary status in general and freedom from specific infective agents in detail provided that import restrictions should be applied. The latter is generally achieved by large national serological surveys and risk assessments. The paper describes the basic structure and application of a generic stochastic model for risk-based sample size calculation of consecutive national surveys to document freedom from contagious disease agents in livestock.MethodsIn the model, disease spread during the time period between two consecutive surveys was considered, either from undetected infections within the domestic population or from imported infected animals. The @Risk model consists of the domestic spread in-between two national surveys; the infection of domestic herds from animals imported from countries with a sanitary status comparable to Switzerland or lower sanitary status and the summary sheet which summed up the numbers of resulting infected herds of all infection pathways to derive the pre-survey prevalence in the domestic population. Thereof the pre-survey probability of freedom from infection and required survey sample sizes were calculated. A scenario for detection of infected herds by general surveillance was included optionally.ResultsThe model highlights the importance of residual domestic infection spread and characteristics of different import pathways. The sensitivity analysis revealed that number of infected, but undetected domestic herds and the multiplicative between-survey-spread factor were most correlated with the pre-survey probability of freedom from infection and the resulting sample size, respectively. Compared to the deterministic pre-cursor model, the stochastic model was therefore more sensitive to the previous survey's results. Undetected spread of infection in the domestic population between two surveys gained more importance than infection through animals of either import pathway.ConclusionThe model estimated the pre-survey probability of freedom from infection accurately as was shown in the case of infectious bovine rhinotracheitis (IBR). With this model, a generic tool becomes available which can be adapted to changing conditions related to either importing or exporting countries.

Association between hepatitis B surface antibody seropositivity and coronary artery disease

Specific infectious agents have been found to be related to the pathogenesis of coronary atherosclerosis. We assessed the possible association between angiographically proven coronary artery disease (CAD) and hepatitis B surface antibody (HBS Ab) seropositivity in a population with relatively high prevalence of hepatitis B virus (HBV) infection. This was a cross-sectional study. We analyzed data from 830 consecutive subjects undergoing coronary angiography, including angiographic results reported by two cardiologists for inter-observer reliability and assessment of HBS Ab status determined by enzyme-linked immunosorbent assay (ELISA). Chi-square test or Fisher's exact test, independent two-sample t test and the Pearson's Correlation Coefficient test were used, as required. Statistics were performed using SPSS software version 13 (SPSS, Chicago, IL). Two hundred forty-nine (30%) subjects had normal angiogram or minimal CAD, and 581 (70%) had significant CAD in at least one major coronary artery. In patients with CAD and in patients without angiographic evidence of significant atherosclerosis, 28.7% and 28.9% respectively were positive for HBV (P=0.954). Mean C-reactive protein levels in subjects with positive and negative HBS Ab were 10.77+/-8.37 mg/L versus 10.33+/-7.64 mg/L respectively (P=0.465). However, C-reactive protein levels in CAD group were significantly higher (P<0.001). Our results suggested hepatitis B surface antibody seropositivity has no relationship with coronary artery disease. Moreover, no significant linear correlation exists between HBS Ab and C-reactive protein levels. However, as previously shown, C-reactive protein level in patients with coronary artery disease is significantly higher than in patients with normal coronary arteries.

Environmental exposure to bacteria and viruses may provide oncolytic protection against cancers, and declining exposure to infections may contribute to a rising incidence of cancer

Over the past century, the incidence of cancer rose markedly in developed countries. Many underlying factors are known, but not all of them. Over the same century, advances in public health and hygiene practically eradicated many infectious illnesses, and exposure to some untargeted infectious agents has also declined. There are reasons to suspect that these two trends are linked. Although some viruses and one bacterium are known to be oncogenic, a high percentage of infectious agents, 71% of viruses tested in one study, have shown oncolytic properties. Some of these agents have minimal or no clinical consequences, and some are - or were - quite ubiquitous. Many types of cancer are unusually susceptible to several different agents, sometimes 10-1000 times more susceptible than normal cells. When wild-type or attenuated viruses are used to treat cancer, they are often more effective with smaller tumors, and it may be that nascent, undetectable cancers are especially vulnerable. Environmental exposure to bacteria and viruses may provide natural protection from cancer by attacking it at this stage, or inducing the body to do so. Immunity to an infectious agent can attenuate its oncolytic effect, but generally does not stop it, so both initial and repeated exposures may be protective. As more direct evidence, treatment of animals with selected live virus vaccines has provided protection from cancer, and in humans, exposure to two specific infectious agents is known to correlate with a reduced risk of cancer. The significant decline in exposure to infectious agents over the past century may have inadvertently weakened this naturally protective mechanism, driving cancer rates up. There is considerable research on the impact of oncogenic agents, but surprisingly little regarding the impact of oncolytic agents on cancer rates. An understanding of the relationship between natural infections and the suppression of cancer may lead to prophylactic measures against cancer, improved public health policies regarding vaccination programs and hygiene, and greater insight into cancer treatment as well.

Sexually transmitted diseases in sexually abused girls and adolescents

The clinical evaluation for suspected child sexual abuse often includes sexually transmitted disease testing. In spite of the high prevalence of sexual abuse, however, most abused children will not have a sexually transmitted disease identified. The low prevalence of sexually transmitted diseases in this population requires special care by the clinician to exclude false-positive test results and to provide appropriate guidance to child protection workers. The likelihood of sexual transmission varies for specific infectious agents and the transmission of infectious agents such as human papillomavirus is complex. Concern about the low positive predictive value of many tests for sexually transmitted diseases in this population is again being demonstrated and clinicians are asked to be cautious in interpreting test results. Clinicians are mandated reporters of suspected child abuse. Treatment of sexually transmitted diseases may need to be delayed pending confirmatory testing of the initial results. HIV postexposure prophylaxis should be considered within hours of the exposure.

Getting strategic about the environment and health

Historically, the physical environment has been a target for public health policy across the globe. This remains the case in developing countries where the enduring infectious and toxic challenge posed by the environment is tangible and its health impact is manifest. However, in Western societies, the relevance of the environment to health has become obscured. Even when this is not the case, the perspective is usually narrow, centering on specific toxic, infectious or allergenic agents in particular environmental compartments. It is rare for importance to be given to a health-determining role for the environment acting through broader psychosocial mechanisms. The result is that environmental manipulation is seen as a cornerstone of the public health response for comparatively few health concerns. This paper considers how public health policies and action on the physical environment may be pursued more optimally. The need for a more strategic approach, which employs a new conceptual model that recognizes the complexity and contextual issues affecting the relationship between the environment and health but retains sufficient flexibility and simplicity to have practical application, is identified. Building on recent work, a model is proposed and pointers are given for its use in a practical context.

Complications obstétricales dans la schizophrénie : étude comparative en population tunisienne

The neurodevelopmental hypothesis in schizophrenia argues that this disorder may be a result of abnormal brain development due to genetic risk and or to environmental injury such as those due to obstetric complications. Very few studies from emerging countries have been published concerning obstetric complications in schizophrenia. However, meteorological, demographic and health factors in most of these countries are different from those in Western countries, and studies in this field may bring more findings. Our objectives were to compare the frequency of obstetric complications in a group of schizophrenic patients compared to two other groups: a group of first-degree relatives and a healthy control group, and to search for the relationships between these complications and the epidemiological and clinical features of schizophrenic patients. The study is a retrospective case-controlled one: a schizophrenic patient group ( N = 55, 43 males and 12 females, median age = 30 years) was compared to a group of non-affected first degree relatives ( N = 40, 31 males and 9 females, median age = 29 years) and to healthy controls without familial psychiatric history ( N = 38, 25 males and 13 females, median age = 29 years), all matched according to age and sex. Obstetric complications were collected at home from the biological mothers at the time of a visit using the McNeil-Sjostrom questionnaire. Schizophrenic patients were clinically assessed using the Positive and Negative Symptoms (PANSS), the General Assessment of Functioning (GAF) and the Clinical Global Impressions (CGI). Obstetric complications frequency was significantly higher in schizophrenic patients: 67,3 versus 20,0% in their non affected relatives and 28,9% in the healthy controls ( P < 0,001). The mean total score of obstetric complications was significantly higher in the schizophrenic group: 1,52 ± 1,47 versus 0,8 ± 1,77 in the non affected relatives and 0,5 ± 0,97 in the healthy controls ( P < 0,001). In the schizophrenic patients, obstetric complications were more frequent during delivery period (50,9%) and neonatal period (45,5 %). More particularly in pre-term births (21,8%), low birth weight and fetal distress (18,2%) and premature rupture of the membranes (16,4%). A statistical relationship was established between obstetric complications frequency, autumn-wintry birth season, low school level and negative symptoms in the PANSS. However, no significant correlation was found between obstetric complications frequency, family psychiatric history and age of onset of schizophrenia. Through an investigation involving mental recall, our results proved a higher frequency of obstetric complications in schizophrenic patients. Our results support the role of obstetric complications in the etio-pathology of schizophrenia, in interaction with other environmental or genetic factors. This association favors the neuro-developmental hypothesis in schizophrenia. Further studies assessing influence of weather, specific infectious agents, and demographic factors could also be relevant.

Tracing the Origins of Autism: A Spectrum of New Studies

Tracing the Origins of Autism: A Spectrum of New Studies

CT-Guided Core Biopsy of Subchondral Bone and Intervertebral Space in Suspected Spondylodiskitis

Our objective was to determine the diagnostic performance of CT-guided core biopsy including both intervertebral disks and subchondral bone in suspected spondylodiskitis and compare the results with those for other biopsy techniques. CT-guided core biopsy of subchondral bone and intervertebral space compares favorably to previously published studies because histology can provide the diagnosis even when no specific infectious agent is isolated.

Time, Space and Contextual Models of the Immunity Tolerance Decision: Bridging the Geographical Divide of Zinkernagel and Hengartner's ‘Credo 2004’

In Credo 2004, Zinkernagel and Hengartner (Z&H) have continued their challenge to the immunological community to reconsider assumptions regarding the most fundamental aspects of adaptive immunity. They have appropriately championed the role of persistent, widely distributed antigen in tolerance induction, parameters that do not figure prominently in most other models. The global theory of immunity they have developed is predominantly based on observations from studies with viruses and tumours. I suggest here that a more successful approach to generating a theory of the default rules of immunity can be obtained through the study of immunity versus tolerance in the setting of transplantation. Transplantation studies lack the confounding variable of competing evolution present in responses to specific infectious agents and tumours and, therefore, more clearly elucidate default rules of immunity. The geographical model in Credo 2004, primarily a one-signal model regulated by antigen, is contrasted with (1) Cohn's time-based two-signal model and (2) a development-context model that postulates distinct central and peripheral tolerance mechanisms.

Infection and Autoimmunity

As the editors imply in their introduction, the relationship of infection and autoimmunity is complex, compelling, and best viewed as a physiologic process and potential consequence of normal immune recognition and immunoregulation. The editors boldly state that reading the chapters in this book brings one to the conclusion that all autoimmune diseases are infectious, until proven otherwise (my paraphrase). Add environmental triggers to the mix, and most investigators would agree. The book is divided into 3 broad sections: mechanisms of autoimmunity; specific infectious agents and their associated autoimmune diseases; and, conversely, specific autoimmune diseases and their associated infectious agents. The chapters in the mechanisms section focus on particular mechanisms, and with 1 exception, are scholarly and well done. However, this section lacks a review or balanced discussion of the various mechanisms of autoimmunity and proof of causation. Fortunately, the first article in the pathogen section by Denman and Rager-Zisman provides an excellent overview. As with any compendium (56 chapters by more than 100 authors), the quality varies, but all are written by investigators who have made substantial contributions to the field. The book is recommended for clinical investigators with some background in infectious disease or immunology as a starting point and ready resource for the current state of knowledge in the field.

Vascular lesions associated with HIV

14 SA JOURNAL OF RADIOLOGY • December 2006 Much of the international literature concerning this topic is based on paediatric cases. Case reports from KwaZulu-Natal (KZN), the region with the highest estimated incidence of HIV-seropositivity in sub-Saharan Africa, currently reported at 36% of the population, report findings in both HIV-positive paediatric and young adult patients. There is otherwise little information available on this subject, and most findings are based on postmortem results. Research and knowledge in this area will be important to prevent, detect and treat the complications of HIV vasculopathy. A wide range of vasculitidies have been identified in HIV-positive patients, and include the following: 1. A vasculitis resulting from specific infective agents. Relatively commonly encountered examples include tuberculosis and cytomegalovirus. 2. A hypersensitivity vasculitis. Vascular lesions associated with HIV

Confirmation of electron microscopy results by direct testing of viruses adhered to grids using nucleic acid amplification techniques

It is possible to visualize rapidly viral particles by electron microscopy (EM) in patient samples and in cell cultures, and characterize the particles on the basis of their size and morphology. In many instances, EM has contributed to the diagnosis of specific infectious agents. Four different types of viruses with different characteristics of particle size, capsid structure, the presence or absence of an envelope, genomic content and stability outside the host were screened and diagnosed by EM at the level of family/genus. The results were confirmed at the species level by elution of the sample material from the grids used for EM examination and nucleic acid amplification. This approach could be valuable in situations where the immediate diagnosis is unclear, or when new infectious agents appear.