Yu.S. Balashov, <Emphasis Type="Italic">Parazitism kleshchei i nasekomykh na nazemnykh pozvonochnykh</Emphasis> (Parasitism of Ticks and Insects on Terrestrial Vertebrates), St Petersburg: Nauka, 2009, 357 p.

Consideration is given to basic concepts of natural focality that remain debatable (natural focus, epizootic and epidemic processes) and to the most relevant problems that largely determine the pathways of further research in this field, such as application of molecular biological methods to the study of natural foci, modes and forms of pathogen existence at the reservation phase, ways of emergence of “new” diseases with natural focality, and current strategy in disease prevention.     

Natural foci of diseases: the development of the concept at the close of the century

E. N. Pavlovski?'s concept of natural focality of diseases and the development of general knowledge about natural foci and their structural (components), functional (mechanisms of pathogen maintenance), and ecosystem-related organization (assortment and interrelations of ecosystems) are reviewed from principal (in authors' opinion) aspects. The 60-year history of this theory includes three stages at which its scope and contents differed. At the first stage, it concerned transmissible zoonoses. It had been assumed that structurally, natural foci necessarily include the pathogen-vector-host triad, and the functioning of the focus is provided for by only pathogen circulation in terrestrial ecosystems. At the second stage, it became clear that vector is not a necessary structural component of any focus (an example of nontransmissible diseases), although the functioning of foci remained to be unequivocally attributed to the continuous pathogen circulation among animals of terrestrial ecosystems. The third stage is characterized by an understanding that, in general, the presence of a warm-blooded host in the focus is also unnecessary for pathogen survival, and natural foci can be represented by soil and aquatic ecosystems. The only necessary and specific component of any natural focus is the pathogen population. In this context, modern views on natural focality of diseases are reviewed, and the essence of the terms "natural focus" and "epizootic process" is defined. It is proposed to distinguish the phases of pathogen reservation and epizootic spread (circulation) in ecosystems of any type. The current state of this concept provides evidence that, in general biological terms, studies on natural focality of diseases belong to one of the fields of symbiotology.     

Main features of natural focality of ixodid tick-borne borreliosis in Russia

In a general form the "key" data on natural focality of ixodid tick-borne borrelioses and ecology of their agents--B. burgdorferi s. 1. in Russia, which have been accumulated by now, are presented. Vectors and reservoir hosts of different species of Borrelia, as well as a landscape preference of natural foci and ecological factors, determining risk of human infection, are characterized.     

Epidemiological surveillance on natural-borne infections in the Ulyanovsk region

The analysis of natural foci of haemorrhagic fever with renal syndrome (HFRS) and tick-borne borreliosis on the territory of the Ulyanovsk region is presented. Reduced rat control interventions result in a wide spread of these and other infections with natural focality. Monitoring of natural foci of HFRS, tick-borne borreliosis and arbovirus infections, their typing and determination of main reservoirs are the most promising among epidemiological surveillance methods.     

Development of views on natural focality of plague

The theory of natural focality of human diseases, basically formulated by Academician E.N. Pavlovsky in 1939, invigorated research on plague, the disease whose epidemics had taken millions of lives in the past. Numerous studies in Russia and abroad have provided a great amount of data on the pathogen, its carriers, and vectors, specific features of infection spread and dynamics of activity of natural plague foci. Over a long period, plague was considered to be an obligate transmissible zoonosis. However, recent laboratory experiments and direct observations in natural foci of this infection indicate that plague is probably a zoophilous sapronosis.     

Results of screening of plasmids of Yersinia pestis strains from various regions of endemic central-asian plague focus

The results of the plasmid screening of Yersinia pestis strains isolated from four autonomous focuses on the northern border of the Central Asian zone of plague natural focality are presented. The plasmid profile of Yersinia pestis strains from the focuses is characterized as stable and independent of the source and time of strain isolation. The peculiar characteristic of the strains isolated in Tuva is the presence of an "additional" 15-16 Md plasmid in those strains.     

The interrelations of the causative agents of transmissible diseases in ixodid ticks (Ixodidae) with a mixed infection

The data on interactions between pathogens of human diseases with natural focality in ixodid ticks (Ixodidae) with mixed infection are reviewed. Different variants of mixed infection revealed in nature and accompanied by predominantly extracellular, or both extra- and intracellular location of the agents in tick organism are considered. Natural mixed infection of ticks by different pathogens is a normal and commonly occurring phenomenon; moreover, there is no experimental evidence for the existence of any antagonistic relationships between spirochetes, rickettsiae, and piroplasms in such ticks. The absence of antagonism between different agents in vectors largely provides a relative autonomy of corresponding parasitic systems and creates conditions for coexistence of different parasitic systems in mixed natural foci.     

Bacterial zoonoses with natural focality: current trends in epidemic manifestation

Current trends in epidemic manifestation of some bacterial zoonoses with natural focality and their role in human infectious pathology have been reviewed and analyzed. Update information on the etiological agents of "emerging" and "re-emerging" infections--Astrakhan spotted fever, bartonellosis, ixodes tick-borne borrelioses, monocytic erhrlichiosis and canine brucellosis, recently isolated on the territory of Russia, is presented. The main factors at play in the process of urbanization of bacterial zoonoses are discussed.     

Role of epidemiological science and practice in protecting the health of the population of the country

The historical stages of the development of epidemiology as a science with a specific object of study, is summarized. One of the greatest theoretical generalizations is the doctrine on the natural focality of diseases. New principles of theoretical epidemiology, new theories and concepts are analyzed. The role of infectious pathology as one of the main criteria of the population health is emphasized as well as a wide spread of infectious (parasitic) diseases. The specific feature of the present stage of epidemiological situation is the dominating and constantly increasing role of viruses in the etiology of infectious diseases. The effectiveness of vaccinal prophylaxis to control vaccine-preventable infections is substantiated. The role of epidemiological science in revealing the epidemiological regularities of emerging and re-emerging infections is emphasized.     

Contribution to the knowledge of home range in common shrew Sorex araneus L.

Summary Population density of shrews in a clearing in the submountain spruce forest was established per 1 hectare 17.5 individuals of common shrew, 4.6 of pygmy shrew and 1.1 of alpin shrew. The mean radius of activity in common shrew amounts to 13 m. The ratio of shrew to rodents was 1:3 or 1:2 in summer and autum respectively. Theoretical home range reached 532 m². The importance of home range studies for synecological studies and theory of natural focality was demonstrated.District Station of Hygiene and Epidemiology, Olomouc, SSR.     

Significance of ixodid tick (Parasitiformes,Ixodidae) population structure for maintenance of natural foci of infection

Basic postulates of the theory of natural focality of infections are considered in terms of modern ecological parasitology using the example of Ixodes ricinus and I. persulcatus ticks, the main vectors of tickborne encephalitis and borrelioses in Eurasia. Consideration is given to data on the population structure of ticks, their distribution in ecosystems, abundance, mortality at different stages of the life cycle, seasonal dynamics of activity, occurrence on different vertebrate species, relationships with potential hosts, and connections agents of infections. Due to long individual life span and development of one generation over 3–6 years, tick vector provide not only for transmission of pathogens, but also for their long-term storage and amplification. Several alternative routes of tick infection of ticks provide for pathogen exchange between individuals at different phases of development within one generation and between feeding ticks of different generations.     

The Old Kinship Studies Confronts Gay Kinship: A Critique of Kath Weston

Kath Weston's highly-acclaimed analysis of gay kinship is examined in the light of the old kinship studies, especially the notion of focality. The verdict is quite contrary to Weston's, viz. that gay kinship and the idea of gay families are structural derivatives of heterosexual kinship and heterosexual families. Weston's work is shown to be part of a larger collectivist project in kinship theory in which key concerns in semantic theory are ignored.     

N-3 Polyunsaturated Fatty Acids of Marine Origin and Multifocality in Human Breast Cancer

Objective

The microenvironment of breast epithelial tissue may contribute to the clinical expression of breast cancer. Breast epithelial tissue, whether healthy or tumoral, is directly in contact with fat cells, which in turn could influence tumor multifocality. In this pilot study we investigated whether the fatty acid composition of breast adipose tissue differed according to breast cancer focality.

Methods

Twenty-three consecutive women presenting with non-metastatic breast cancer underwent breast-imaging procedures including Magnetic Resonance Imaging prior to treatment. Breast adipose tissue specimens were collected during breast surgery. We established a biochemical profile of adipose tissue fatty acids by gas chromatography. We assessed whether there were differences according to breast cancer focality.

Results

We found that decreased levels in breast adipose tissue of docosahexaenoic and eicosapentaenoic acids, the two main polyunsaturated n-3 fatty acids of marine origin, were associated with multifocality.

Discussion

These differences in lipid content may contribute to mechanisms through which peritumoral adipose tissue fuels breast cancer multifocality.     

Transcranial magnetic stimulation: studying the brain-behaviour relationship by induction of 'virtual lesions'.

Transcranial magnetic stimulation (TMS) provides a non-invasive method of induction of a focal current in the brain and transient modulation of the function of the targeted cortex. Despite limited understanding about focality and mechanisms of action, TMS provides a unique opportunity of studying brain-behaviour relations in normal humans. TMS can enhance the results of other neuroimaging techniques by establishing the causal link between brain activity and task performance, and by exploring functional brain connectivity.     

Nonrandom Distribution of Vector Ticks (Dermacentor variabilis) Infected by Francisella tularensis

The island of Martha''s Vineyard, Massachusetts, is the site of a sustained outbreak of tularemia due to Francisella tularensis tularensis. Dog ticks, Dermacentor variabilis, appear to be critical in the perpetuation of the agent there. Tularemia has long been characterized as an agent of natural focality, stably persisting in characteristic sites of transmission, but this suggestion has never been rigorously tested. Accordingly, we sought to identify a natural focus of transmission of the agent of tularemia by mapping the distribution of PCR-positive ticks. From 2004 to 2007, questing D. variabilis were collected from 85 individual waypoints along a 1.5 km transect in a field site on Martha''s Vineyard. The positions of PCR-positive ticks were then mapped using ArcGIS. Cluster analysis identified an area approximately 290 meters in diameter, 9 waypoints, that was significantly more likely to yield PCR-positive ticks (relative risk 3.3, P = 0.001) than the rest of the field site. Genotyping of F. tularensis using variable number tandem repeat (VNTR) analysis on PCR-positive ticks yielded 13 different haplotypes, the vast majority of which was one dominant haplotype. Positive ticks collected in the cluster were 3.4 times (relative risk = 3.4, P<0.0001) more likely to have an uncommon haplotype than those collected elsewhere from the transect. We conclude that we have identified a microfocus where the agent of tularemia stably perpetuates and that this area is where genetic diversity is generated.     

Accumulation of 7S SNARE complexes in hippocampal synaptosomes from chronically kindled rats

Kindling is a model of complex partial epilepsy wherein periodic application of an initially subconvulsive stimulus leads to first limbic and then generalized tonic-clonic seizures. Several laboratories have reported that augmented neurotransmitter release of l-glutamate is associated with the chronically kindled state. Neurotransmitter release requires membrane proteins called SNAREs, which form transmembrane complexes that participate in vesicle docking and are required for membrane fusion. We show here that kindling by entorhinal stimulation is associated with an accumulation of 7S SNARE complexes in the ipsilateral hippocampus. This increase of 7S SNARE complexes appears to begin early in the kindling process, achieves a peak with full kindling, and remains at this level for at least a month following cessation of further kindling stimuli. The increase is focal and permanently limited to the ipsilateral hippocampus despite progression to generalized electrographic and behavioral seizures. It is not seen in animals that receive electroconvulsive seizures, suggesting it is related to the kindling process itself. The duration and focality of increased 7S SNARE complexes with entorhinal kindling suggest that this is an altered molecular process associated with epileptogenesis.     

Endemicity, focality and seasonality of transmission of human schistosomiasis in Amagunze Village, eastern Nigeria

The pattern of transmission of human schistosomiasis was studied in Amagunze Village, eastern Nigeria, during 1986-1987. The prevalence of Schistosoma haematobium in 119 schoolboys aged 5-12 years was 79%. The geometric mean of intensity of infection was 49 eggs/10 ml urine and the frequency of visible haematuria was 25.2%. No S. mansoni infections were demonstrated. A marked seasonality in population density of Bulinus truncatus, B. forskalii and Biomphalaria pfeifferi was demonstrated with reduced densities during the late rainy and early dry seasons. Schistosoma sp. infected B. truncatus were found in the late dry and early rainy seasons in 2 out of 7 major human water contact sites studied. Seasonality and focality of transmission of S. haematobium and its high endemicity in the area were thus demonstrated.     

Incidence of meningococcal infection in the RSFSR]

The authors present characteristics of meningococcus infection epidemic process in case of sporadic cases and under epidemic conditions (1965--1976). A scheme of epidemiological analysis suggested by the authors permitted to differentiate and to record the incidence of various clinical forms of meningococcus infection, to present data on the age, seasonal characteristics, focality, etc. Comparison of intensive morbidity indices for 10 years, both at the individual administration territories and in the Republic as a whole demonstrated morbidity level of 1.5--2.0 to be one of prognostic signs of the beginning epidemic. The main features differentiating the sporadic and epidemic morbidity periods were revealed. The presence of group diseases, a greater percentage of children among those who fell ill, and marked signs of seasonality and territorial difference characterized the period of rise caused by meningococcus of serological group A.     

Prevalence of malaria in Ouagadougou and the surrounding rural environment during the period of maximal transmission

The prevalence of malaria infections was estimated in six different areas of the town of Ouagadougou, Burkina Faso, and in three neighbouring villages. Thick and thin blood films from a total of 2,117 children less than 5 years old were examined at the peak of the transmission season (August-September). Plasmodium falciparum was found in more than 98% of the positive slides. The overall parasite index at Ouagadougou was 16%, while indices from 51 to 88% were recorded in the three villages. Significant differences were observed between the six urban areas within the town as well as between the three villages. The highest parasite rates in the town were clearly associated with major breeding places of An. gambiae s.l. indicating a remarkable focality of transmission. Significant differences were observed between groups of children from houses only 300 m apart. Chemoprophylaxis appears to play an important role in determining parasite rates lower than expected in one of the three villages.