Estimation of population attributable fractions from fitted incidence ratios and exposure survey data, with an application to electromagnetic fields and childhood leukemia

Standard presentations of epidemiological results focus on incidence-ratio estimates derived from regression models fit to specialized study data. These data are often highly nonrepresentative of populations for which public-health impacts must be evaluated. Basic methods are provided for interval estimation of attributable fractions from model-based incidence-ratio estimates combined with independent survey estimates of the exposure distribution in the target population of interest. These methods are illustrated in estimation of the potential impact of magnetic-field exposures on childhood leukemia in the United States, based on pooled data from 11 case-control studies and a U.S. sample survey of magnetic-field exposures.     

Crimean-Congo haemorrhagic fever in southern Russia

At the end of the 20th--the beginning of the 21st century activation of a natural focus of Crimean-Congo haemorrhagic fever (CCHF) in southern Russia was noted. As a consequence, in 2002 outbreaks and sporadic cases of this disease were registered on the territory of 6 out of 13 administrative units of the Southern Federal District. To minimize the epidemiological consequences of the aggravating epidemiological situation considerable efforts and means were required from health care organs and institutions of the state sanitary and epidemiological service, including essential financial expenditures. The results of natural foci of CCHF survey, obtained by 2002, as well as main trends of prophylactic and antiepidemic interventions are presented. Scientific research and practical observations made it possible to work out a number of methodological regulations concerning the diagnostics, treatment and prophylaxis of CCHF.     

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.     

Spread of Leishmania killicki to Central and South-West Tunisia

Twenty cutaneous leishmaniasis (CL) cases were notified from December 2001 to February 2002, in a small village in the district of Oueslatia (governorate of Kairouan, central Tunisia) which is an endemic focus of infantile visceral leishmaniasis due to leishmania (L.) infantum and that had never been concerned previously by CL. The parasite typing of two isolates obtained from two children that have never left the region has identified L. killicki. This species had only been reported previously in a limited focus of Tunisian Southeast. In October 2002, an epidemiological survey with isoenzym characterization of the parasite led in a well-known focus of zoonotic cutaneous leishmaniasis of South-West Tunisia also revealed the presence of L. killicki. These results suggest the spread of this species and stress the need of further investigations for a better control of CL in Tunisia.     

Epidemiological situation on tularemia in the regions of Stavropol Territory affected by flood

The data obtained in the analysis of the epidemiological situation in tularemia in the zone of inundation in the Stavropol Territory in 2002 are presented. The current systematic epidemiological surveillance, as well as the data of urgent epizootological and epidemiological survey in the zone of inundation permitted the objective prognostication of the situation in tularemia and formed the basis for the rational planning and realization of prophylactic measures.     

New cases of human diphyllobothriasis in Panguipulli, Chile

A retrospective laboratory survey on 10758 patients at the Hospital of Panguipulli showed the existence of 11 cases of diphyllobothriasis during a ten year (1979-1988) period. Age and sex as well as data of biannual prevalence of diphyllobothriasis are given. Some factors that determine the existence of diphyllobothriasis focus at lakes from Valdivia River Basin are briefly reviewed.     

Crimean-Congo hemorrhagic fever in Rostov Province: the epidemiological characteristics of an outbreak

The results of the epidemiological analysis of the outbreak of hemorrhagic fever which was caused by Crimean-Congo hemorrhagic fever virus and occurred during the period of July 3-19, 1999, in the Oblivskaya district of Rostov Province are presented. The specific epidemiological features of the outbreak have been determined. The possible versions of the appearance of the focus of infection and the role of Ixodes ticks in the circulation of the infective agent are discussed.     

Screening of Trypanosoma brucei gambiense in Domestic Livestock and Tsetse Flies from an Insular Endemic Focus (Luba,Equatorial Guinea)

Background

Sleeping sickness is spread over 36 Sub-Saharan African countries. In West and Central Africa, the disease is caused by Trypanosoma brucei gambiense, which produces a chronic clinical manifestation. The Luba focus (Bioko Island, Equatorial Guinea) has not reported autochthonous sleeping sickness cases since 1995, but given the complexity of the epidemiological cycle, the elimination of the parasite in the environment is difficult to categorically ensure.

Methodology/Principal Findings

The aim of this work is to assess, by a molecular approach (Polymerase Chain Reaction, PCR), the possible permanence of T. b. gambiense in the vector (Glossina spp.) and domestic fauna in order to improve our understanding of the epidemiological situation of the disease in an isolated focus considered to be under control.The results obtained show the absence of the parasite in peridomestic livestock but its presence, although at very low rate, in the vector. On the other hand, interesting entomological data highlight that an elevated concentration of tsetse flies was observed in two out of the ten villages considered to be in the focus.

Conclusions

These findings demonstrate that even in conditions of apparent control, a complete parasite clearance is difficult to achieve. Further investigations must be focused on animal reservoirs which could allow the parasites to persist without leading to human cases. In Luba, where domestic livestock are scarcer than other foci in mainland Equatorial Guinea, the epidemiological significance of wild fauna should be assessed to establish their role in the maintenance of the infection.     

Cholera in Kazan. Organization and implementation of cholera control interventions

Data on emergent epidemiological analysis of the cholera outbreak in Kazan are presented. A version of the cholera focus emergence was confirmed, namely water route of transmission as a result of bathing in a water reservoir where sewage waters had penetrated. The outbreak had local and acute character. The complex of cholera control interventions aimed at localization and liquidation of the focus proved to be effective.     

A stable focus of canine leishmaniosis in the Bologna Province, Italy

During an epidemiological survey carried out for two consecutive years (2001-2002), autochthonous cases of canine leishmaniosis (CanL) were reported in Communes of the Bologna Province (Emilia-Romagna Region, northern Italy), involved in the past (1971-1972) in a severe outbreak of human visceral leishmaniosis (VL). Serological controls, carried out by immunofluorescence antibody test on a sample of owned dogs, detected a mean prevalence of 2.5% in the first year in 4 Communes, and of 11.2% in the second year in only one Commune, where an incidence value of 9.3% was assessed. The autochthonous origin of the infection was confirmed in 11 out of 13 positive animals in the first year and in 5 out of 6 new cases in the second year. In one case the parasitological examinations led to the isolation of leishmaniae characterized as Leishmania infantum zymodeme MON 1. Entomological surveys carried out during two sandfly seasons in one of the areas concerned by the VL outbreak showed the presence of Phlebotomus perfiliewi and, to a lesser extent, of P perniciosus, both proven vectors of L. infantum in Italy. The results obtained seem to suggest the presence of a stable focus of CanL in the territory involved in the previous VL outbreak of 1971-1972, within which the infection in the canine population had been assessed only serologically. Such an epidemiological situation may be seen either as the persistence of an old focus or as a new imported one.     

The current systematics and taxonomy of the powdery mildews (Erysiphales): an overview

A brief survey of the current systematics and taxonomy of powdery mildews (Erysiphales) is given with special focus on new characters used for taxonomic purposes as well as new approaches, methods and techniques. The structure of the family Erysiphaceae based on phylogenetic results is summarized, and the current, strongly increased number of powdery mildew taxa in a planned new monographic treatment of this fungal group is given and compared with the old monograph from 1987.     

Rare genera of actinomycetes as potential producers of new antibiotics

A literature survey covering more than twenty-three thousand bioactive microbial products including eight thousand antiinfectives demonstrated the increasing relevance of the so called 'rare' actinomycetes as a source of new antibiotics. Past and present efforts in the isolation of rare actinomycetes have enriched the Biosearch Italia Strain Collection with more than twenty thousand strains, showing that, when selective isolation methods are developed and extensively applied, some genera, such as Actinomadura, Actinoplanes, Micromonospora, Microtetraspora, are not rare at all and can be recovered from many soil samples. The current focus is on the isolation of members of Streptosporangiaceae family, given their promising chemical diversity.     

Genetics of schizophrenia and smoking: an approach to studying their comorbidity based on epidemiological findings

The association between schizophrenia and tobacco smoking has been described in more than 1,000 articles, many with inadequate methodology. The studies on this association can focus on: (1) current smoking, ever smoking or smoking cessation; (2) non-psychiatric controls or controls with severe mental illness (e.g., bipolar disorder); and (3) higher smoking frequency or greater usage in smokers. The association with the most potential for genetic studies is that between ever daily smoking and schizophrenia; it may reflect a shared genetic vulnerability. To reduce the number of false-positive genes, we propose a three-stage approach derived from epidemiological knowledge. In the first stage, only genetic variations associated with ever daily smoking that are simultaneously significant within the non-psychiatric controls, the bipolar disorder controls and the schizophrenia cases will be selected. Only those genetic variations that are simultaneously significant in the three hypothesis tests will be tested in the second stage, where the prevalence of the genes must be significantly higher in schizophrenia than in bipolar disorder, and significantly higher in bipolar disorder than in controls. The genes simultaneously significant in the second stage will be included in a third stage where the gene variations must be significantly more frequent in schizophrenia patients who did not start smoking daily until their 20s (late start) versus those who had an early start. Any genetic approach to psychiatric disorders may fail if attention is not given to comorbidity and epidemiological studies that suggest which comorbidities are likely to be explained by genetics and which are not. Our approach, which examines the results of epidemiological studies on comorbidities and then looks for genes that simultaneously satisfy epidemiologically suggested sets of hypotheses, may also apply to the study of other major illnesses.     

An epidemiological analysis of postoperative suppurative pathology in surgical hospitals]

Approaches to the epidemiological analysis of postoperative wound complications in surgical hospitals are summarized. The indices for the evaluation of the epidemic situation in surgical departments (the ratio of severe and mild forms of complications, severe and posthospital complications) are proposed. To determine the site of infection, the method of graphic analysis, involving the fixation of dates of the operation and the appearance of the complication and taking into account regularities in the development of the outbreak, the depth and severity of the lesion, is proposed. Epidemiological surveillance at medical institutions permits the prognostication of the epidemiological situation. The realization of epidemiological surveillance at the level of individual medical institutions is the prerequisite of effective functioning of the program of epidemiological surveillance at a given territory.     

Current trends in the epidemiological typing of clinically relevant microbes in Europe

A questionnaire-based survey was performed to accumulate data on methodologies used in microbiology laboratories involved in epidemiological typing. Genotyping by PFGE and MLST are currently clearly preferred over phenotyping. The overall wish is to increase the activities by over 20% and additional resources would be used to invest in real-time typing.     

National epidemiologic study on hydatidosis

The results of an epidemiological survey on surgical cases of human hydatidosis in 9 italian regions (Central, Southern and Insular Italy) with the highest incidence of disease and a population of 27,054,000 inhabitants are reported. The period considered was from 1980 through 1984. 2,592 cases have been collected and related to sex, age, occupation, residence of surgically treated patients and cyst localization. Comparison of results from the present and a previous survey was carried out.     

Hemagglutinating test for HBsAg and antibodies in epidemiological practice

The use of Alsever's solution has abolished the necessity for taking intravenous blood and made it possible to divide the determination of HBsAg and antibodies to this antigen into two stages. The combined determination of HBsAg and its antibodies by the third-generation techniques improves the quality of the epidemiological survey of hepatitis B cases and the epidemiological observation of risk groups.     

Distribution of echinococcosis/hydatidosis in Italy

Results of an epidemiological survey carried out in 88 slaughterhouses in Italy from 1979 to 1983 are reported. Data have been compared to national surveys previously conducted in 1955 and from 1968 to 1978. Analysis of various factors affecting the incidence of the disease in different areas of the country are reported.     

Results of conducting an epidemiological survey of diphtheria in 21 territories of the RSFSR

As the result of epidemiological survey of diphtherial infection, carried out in conformity with the unified methodological recommendations in 21 regions of the RSFSR during 1980-1981, the expediency of such experiment was established. Immunity to diphtheria in children aged up to 14 years was high: children with negative Schick tests constituted 96.9-99.1%. No biological changes in Corynebacterium diphtheriae occurred during the term of observation. Toxigenic C. diphtheriae showed a high level of pathogenicity. The epidemiological survey contributed to a more thorough detection of diphtheria patients and carriers releasing toxigenic C. diphtheriae. The quality of clinical bacteriological diagnosis improved. In rare cases angina with the concomitant carriership of toxigenic C. diphtheriae could be diagnosed with the indispensable serological examination of the patients by Jensen's method.     

A contribution to the interpretation of immunological survey records

In certain infection types the use of official immunological survey figures expressed mathematically by means of exponential distribution or its distributional function may help assess the epidemiological trends in herd immunity levels. This approach to the evaluation of immunological survey records is primarily well applicable to infections that are uniform in exposure pattern, affect the entire population, and result in life-long immunity. The parameters characterizing the rise in the level of herd immunity can be determined by means of negative exponential regression. Applied to selected immunological survey data this essentially simple catalytic model of investigation may provide reliable information on the actual state of immunity in the general population, and may also help estimate its dynamics in the retrospect.