Influence of ship motion on waterway. Backward current velocity

In this work was presented an influence of bow form of inland waterways ship and waterway limitations on values of backward current velocity. The analysis was performed on the basis of results of calculations with the use of numerical modeling the flow around ship hull. The applied HPSDK computation system (a computer software developed by these authors) is based on using surface distribution of vorticity to analyze the velocity field and pressure distribution around ship hull. It was proved that the generated backward current velocity exceeded its permissible non-scouring values

Current state of the waterway along the Warta and Noteć Rivers

In June 2004 took place an inspection trip aimed at assessing current state of the east-west waterway connecting the Odra and Wisła Rivers; during the trip a photographic documentation of the region was made as well. The below presented text contains also some conclusions resulting from the trip

Influence of ship–generated waves on waterway

Results are presented of calculations of ship – generated waves during its motion in canal. For the calculations FLUENT software was used. It was demonstrated that ship generates waves which, when approaching canal slopes, may constitute an important factor in deteriorating the banks, and that ship’s wave resistance can be used as an assessment measure of influence of ship motion on waterway. The methods which are based on approximate formulae, are not reliable. The FLUENT software may be applied as a numerical towing tank

The role of particular tick developmental stages in the circulation of tick-borne pathogens affecting humans in Central Europe. 3. Rickettsiae

Ixodes ricinus, Dermacentor reticulatus and D. marginatus ticks are the most important vector for Rickettsia spp. in Central Europe. Ticks sustain rickettsial transmission cycles transovarially and transstadially, it makes enable the rickettsial circulation in the tick population in the absence of vertebrate competent reservoir. Rickettsia helvetica is transmitted by I. ricinus tick; the highest rates of infection are noted in adult females, lower in males and in nymphs. All tick developmental stages apart males are able to infect mammal hosts and humans. The potential animal reservoir could be wild boar, the role of deer is unclear; small rodents maintain the tick population. Rickettsia slovaca is transmitted by D. marginatus and D. reticulatus ticks. The available data suggest the role of wild boars and Apodemus mice as animal reservoir. The ticks able to infect human are adults D. marginatus. Rickettsia raoultii is transmitted by D. marginatus and D. reticulatus. The infections of mammals are not recorded. As in Rickettsia slovaca, human can be infected by adults D. marginatus. Rickettsia monacensis is transmitted in Central Europe by I. ricinus tick (apart males), although there is a documented infection of Dermacentor ticks. The differences in the infection rates of tick’s larvae, nymphs and adults suggest the limited role of transovarial transmission, and the participation of mammals in the zoonotic cycle, being the source of infection for larvae and nymphs

Molecular screening for Bartonella henselae and Borrelia burgdorferi sensu lato co-existence within Ixodes ricinus populations in central and eastern parts of Poland

The presented study aimed at establishing the prevalence and co-infection rates of Bartonella henselae and Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from the central and eastern parts of Poland. The common tick individuals were gathered in the years 2008-2009. Questing ticks were sampled by dragging a white woollen flag over lower vegetation at 17 localities within diverse types of habitats: urban recreational green areas (city parks and squares), suburban forests and rural woodlands throughout the investigated regions of Poland. Detection of B. henselae in tested tick specimens was based on PCR amplification of the citrate synthase (gltA) gene, while screening for the presence of B. burgdorferi s.l. DNA was carried out by analyzing fragments of two genes: the flagellin (fla) and outer surface protein A (ospA). A total number of 1,571 I. ricinus ticks were sampled: 865 (55.1%) nymphs, 377 females (24.0%) and 329 males (20.9%). The application of PCR assays revealed that 76 (4.8%) tick samples were B. henselae-positive, B. burgdorferi s.l. DNA was detected in 194 specimens (12.3%), whereas the co-existence of these pathogens was evidenced in 22 tested ticks (1.4%). Furthermore, the occurrence of bartonellae and co-circulation of analysed microorganisms in I. ricinus was affirmed only within adult individuals, while presence of the screened spirochetes was ascertained in both nymphal and adult ticks. It should be stressed that the suburban woods of Warsaw and rural forests in Warsaw County characterized the highest prevalence levels of dual infection with investigated tick-borne pathogens, whereas the lowest co-infection rates were recorded in tick populations inhabiting rural forests in Płock County and forested areas in Korczew-Mogielnica (within the Nadbużański Landscape Park)

The role of particular ticks developmental stages in the circulation of tick-borne pathogens in Central Europe. 4. Anaplasmataceae

In Central European conditions, two species of Anaplasmataceae have epidemiological significance – Candidatus Neoehrlichia micurensis and Anaplasma phagocytophilum. Tick Ixodes ricinus is considered as their main vector, wild mammals as the animal reservoir. There is presented the transstadial transmission in ticks, due to the lack of transovarial mode the circulation goes mainly between immature ticks and hosts; pathogen circulates primarily in the cycle: infected rodent → the tick larva → the nymph → the mammal reservoir → the larva of the tick. The tick stages able to effectively infect human are nymphs and adult females, males do not participate in the follow transmission. The summary of available data of different A. phagocytophilum strains associations with different hosts revealed at least few distinct enzootic cycle, concern the same ticks species and different mammal hosts. It is possible to reveal in Central Europe the existence of at least three different epidemiological transmission cycles of A. phagocytophilum. The first cycle involves strains pathogenic for human and identical strains from horses, dogs, cats, wild boars, hedgehogs, possibly red foxes. The second cycle involves deer, European bison and possibly domestic ruminants. The third cycle contains strains from voles, shrew and possibly Apodemus mice. In Western Europe voles might be involved in separate enzootic cycle with Ixodes trianguliceps as the vector