Category: Epidemiology

Epstein-Barr virus infection and associated diseases in children. I. Pathogenesis, epidemiology and clinical aspects

Abstract:

Epstein-Barr virus (EBV), an ubiquitous human B lymphotropic virus, is the cause of infectious mononucleosis. Moreover, EBV infection can be followed by lymphoproliferative diseases in patients with inherited and acquired immunodeficiencies.

Primary EBV infection may be a threat to all children after marrow or organ transplantation or those receiving chronic immunosuppressive treatment for various other reasons. The virus has been also implicated in the pathogenesis of different malignant tumours such as Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkin disease and some T-cell lymphomas.

This review focuses on various aspects of virus-host interactions, immune mechanisms of the host, and the still experimental therapeutic approaches in EBV-associated diseases.

 

Source: Schuster V, Kreth HW. Epstein-Barr virus infection and associated diseases in children. I. Pathogenesis, epidemiology and clinical aspects. Eur J Pediatr. 1992 Oct;151(10):718-25. http://www.ncbi.nlm.nih.gov/pubmed/1330572

 

The epidemiology of fatigue: more questions than answers

Fatigue syndromes, though recognised for some time, have recently attracted a variety of new diagnostic labels, as well as both professional and media controversy. However, most of the arguments surround the interpretation of small hospital based case-control studies using highly selected groups of patients.’ There is relative silence on population based studies, which perhaps contributes to the lack of concensus. This paper reviews the epidemiology of fatigue in the general population and in primary care and examines potential sources of bias in hospital based studies

You can read the rest of this article here:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1059513/pdf/jepicomh00209-0006.pdf

 

Source: Lewis G, Wessely S. The epidemiology of fatigue: more questions than answers. J Epidemiol Community Health. 1992 Apr;46(2):92-7. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1059513/

 

Post-viral fatigue syndrome. Epidemiology: lessons from the past

Abstract:

This chapter outlines the recorded epidemiological history of PVFS (including the early epidemics of myalgic encephalomyelitis) and the development of the concept, including the realisation that endemic cases also occur.

Cases of PVFS are still not recorded by the Surveillance Centre for Communicable Diseases, so it is very difficult to detect and monitor any outbreak in the community, since each GP may only have two or three such patients and would, therefore, not be aware of an epidemic in the community as a whole if it occurred.

Epidemiological issues raised by the early epidemics, including the delineation of the syndrome, the question of bias, the role of hysteria and the role of depression; the issue of symptom distribution, and its implications for aetiology; and a multiaxial framework for understanding the association with psychological symptoms are discussed. The value of a future multidisciplinary research programme designed to disentangle direct and predisposing causes of PVFS is emphasised.

 

Source: Jenkins R. Post-viral fatigue syndrome. Epidemiology: lessons from the past. Br Med Bull. 1991 Oct;47(4):952-65. http://www.ncbi.nlm.nih.gov/pubmed/1794093

 

Post-viral fatigue syndrome. Epidemiology: a critical review

Abstract:

Numerous reports in medical journals, lay magazines, and newspapers bear witness to the level of interest in the postviral fatigue syndrome and the heated controversy about the true nature of this condition. For many, it represents a ‘rag bag’ diagnosis into which unsolved diagnostic problems are discarded. Others are in no doubt that there is a discrete syndrome, probably with a specific causation.

The real answer almost certainly lies somewhere in between, but the truth can only be established through epidemiological studies designed to answer key questions. Does it exist at all, and, if so, how frequently does it occur? Who is most likely to get it and what is its cause? What is the nature of its implied association with viral infections and what is the role of other frequently postulated factors, such as psychiatric morbidity? What is its natural history and is there any evidence that any of the treatment/management regimes on offer can effectively lead to symptomatic relief or improve prognosis?

In this chapter, we consider the evidence on these key questions, identify some of the deficiencies in our current knowledge and highlight the kind of research which is still required.

 

Source: Wallace PG. Post-viral fatigue syndrome. Epidemiology: a critical review. Br Med Bull. 1991 Oct;47(4):942-51. http://www.ncbi.nlm.nih.gov/pubmed/1794092

 

Issues and problems in the conduct of epidemiologic research on chronic fatigue syndrome

Abstract:

The epidemiologic research approach is perhaps most appropriate for initial studies of chronic fatigue syndrome since the syndrome is vaguely defined, scientific knowledge about it is limited, and an infectious etiology is suspected.

Several priority needs appropriate for epidemiologic research are identified, including a refinement of diagnostic criteria; a greater understanding of the natural history of the syndrome; basic incidence, prevalence, and mortality statistics; information on whether asymptomatic cases exist; etiologic studies of possible heterogeneity of cases; investigations of clusters of cases; and determinations of whether patients with the syndrome have an increased risk of malignancy.

Because of the lack of cogent etiologic hypotheses regarding the syndrome, case-control studies are identified as a high priority for research. The many difficulties encountered in conducting such research are discussed and approaches to dealing with these problems are suggested.

 

Source: Grufferman S. Issues and problems in the conduct of epidemiologic research on chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S60-7. http://www.ncbi.nlm.nih.gov/pubmed/2020803

 

Serologic and virologic epidemiology of Epstein-Barr virus: relevance to chronic fatigue syndrome

Abstract:

Patients considered to have chronic fatigue syndrome (CFS) have been reported to exhibit an increased antibody response to Epstein-Barr virus (EBV) early antigen complex and capsid antigen, findings that suggest some relationship between EBV and CFS.

However, the serologic findings have not been totally consistent among different study groups, and the antibody patterns in asymptomatic individuals may be similar. Moreover, patients with symptomatology indicative of CFS do not appear to have an abnormal burden of EBV in body fluids and manifest only a variable, mild degree of EBV-specific cell-mediated responses.

The evidence is growing that the serologic findings of an enhanced EBV state in individuals with CFS-like manifestations, as well as the subsequent reports of increased antibody titers to other viruses, reflect a generalized underlying immunologic dysfunction in these patients.

Future studies with criteria-defined CFS study groups in which determinations are made of antibody responses to newly identified EBV-associated nuclear antigen components and distinct EBV proteins in addition to specific virologic and immunologic analyses of EBV may be worthwhile as a means of clarifying the association between EBV and CFS.

 

Source: Sumaya CV. Serologic and virologic epidemiology of Epstein-Barr virus: relevance to chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S19-25. http://www.ncbi.nlm.nih.gov/pubmed/1850540

 

Molecular approaches to epidemiologic evaluation of viruses as risk factors for patients who have chronic fatigue syndrome

Abstract:

One approach to understanding the chronic fatigue syndrome might be to carry out prospective studies of fatigue that occurs following infection with viral diseases of known etiology, such as influenza, hepatitis, and infectious mononucleosis. Among the viral parameters that should be evaluated are virus burden, variation of virus strain, sites of viral replication, and the state of the viral life cycle (e.g., latent or replicative). Immunologic studies should focus on the humoral and cellular responses to defined viral gene products to identify subtle, individual variations in immune recognition of specific viral subcomponents.

 

Source: Miller G. Molecular approaches to epidemiologic evaluation of viruses as risk factors for patients who have chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S119-22. http://www.ncbi.nlm.nih.gov/pubmed/1850537

 

Analysis of clinical, epidemiologic, and laboratory data on chronic fatigue syndrome

Abstract:

Much of the research conducted on chronic fatigue syndrome (CFS) is exploratory. The researchers’ overall goal is to use clinical, epidemiologic, and laboratory data to provide clues about the etiology of this syndrome. In preparation for this symposium, a review of numerous publications on CFS has indicated that the literature generally does not reflect the application of optimal statistical methods for exploration of data.

Whenever the researchers’ aim is to generate hypotheses, modern methods designed specifically for exploratory data analysis are likely to provide greater insights into any patterns of data than are the traditional approaches to hypothesis testing. In addition, the use of formal methods of data synthesis for ongoing and future research on CFS is a means of strengthening collaborative efforts and of improving the ability of researchers to interpret the evidence available that relates to specific etiologic factors. The inclusion on the research team of experienced biostatisticians, who would oversee the statistical methods and the development of innovative analyses, is recommended.

 

Source: Redmond CK. Analysis of clinical, epidemiologic, and laboratory data on chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S90-3. http://www.ncbi.nlm.nih.gov/pubmed/1826967

 

Asthenic symptoms in a rural family practice. Epidemiologic characteristics and a proposed classification

Abstract:

Asthenic symptoms (eg, fatigue, lassitude, weakness) are of major concern in family practice setting, yet relatively little research has addressed this issue. A retrospective chart review over a 10-year period was conducted to better characterize these symptoms in a rural family practice providing health care to 508 adult patients.

Asthenic complaints were recorded at least once in the medical charts of 164 patients (32%) with a preponderance of female patients. Peak prevalence occurred in the third decade of age and during the summer months. Associated symptoms, mainly pain and dizziness, were reported in 75% of the cases. A cause or diagnosis was not identified by the practicing physician in nearly 50% of the encounters; nevertheless, most episodes resolved spontaneously.

Patients could be subclassified into three categories according to the recurrence pattern of their asthenic symptoms during the study period. The largest category (64%) included patients who had a single or two episodes and was thus termed “episodic asthenia.” Forty-five patients (27%) with recurrent episodes (mean 4.4, range 3 to 10) were classified as having “recurrent episodic asthenia.”

A third small group (14 patients, 9%) with persistent complaints over the years but no evidence of the chronic fatigue syndrome were classified as having “chronic persistent asthenia.” The proposed classification may help future research of asthenic symptoms in the family practice setting.

 

Source: Shahar E, Lederer J. Asthenic symptoms in a rural family practice. Epidemiologic characteristics and a proposed classification. J Fam Pract. 1990 Sep;31(3):257-61; discussion 261-2. http://www.ncbi.nlm.nih.gov/pubmed/2391456