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At least 1,063 records · Page 59Linked to original sources
PubMed1997

[Determination of actual risk factors for malaria infection for travelers by means of measurement of circumsporozoite antibodies].

Measurement of antibodies to circumsporozoite (CS) antigen of Plasmodium falciparum can be used as reliable indicator of malaria transmission in endemic areas. Sensitivity and specificity of an ELISA testkit for the detection of CS antibodies were assessed. In a second step, in order to estimate the actual rate of malaria infection, the prevalence of CS antibodies in serum was investigated in a selected population of travellers returning from sub-Saharan Africa and presenting without any clinical sign of malaria by use of an ELISA. CS antibodies could be detected in 47 out of the 222 investigated patients (21.2%), while 175 (78.8%) tested negative. Both groups did not differ in sex, age, destination or duration of journey or symptoms after return. There was, however, a considerable difference in travel type noticeable: 134 out of the 175 CS-negative patients (76.6%) travelled on a package tour, while this was only true for 8 out of the 47 CS-positive patients (17%, p < 0.001). These data demonstrate the importance of adequate malaria chemoprophylaxis in non-immune travellers to highly endemic areas.

Animals↗
PubMed1997

[Traveller counseling by embassies and consulates].

BACKGROUND: Before travelling to developing countries is necessary to seek accurate health advice. This paper evaluate the quality of travel information given out in Spain by other embassies and consulates of different countries. METHODS: The information was regarded through a telephone survey calling to 32 embassies and consulates of countries in Asia, Africa and South and Central America posing as potential travellers seeking advice. RESULTS: Of the 15 countries where yellow fever is endemic only 53% advised the appropriate immunization. Malaria prophylaxis was recommended in over 41% of the countries in areas of risk for malaria, denning the existence of malaria the 25%. Other immunizations such as hepatitis, tetanus, typhus was recommended by the 12.5% and over 25% mentioned additional precautions (water purification, insect repellents, food ...). 53% referred us to other sources of information in public health departments and travel clinics. CONCLUSIONS: Diplomatic representations are still not an ideal source of pretravel advice. An accurate advice should be sought from health units of international vaccines and Tropical Medicine.

Counseling↗
PubMed1997

[Unauthorized vaccines put on the market are useful for certain travelers].

Certain vaccines such as the amaril vaccine are highly recommended and even required from the traveller. Other vaccinations concern persons travelling in regions where they might be infected by pathogens not present in their countries of origin. There exist vaccines which are available in certain countries but which are not (or not yet) allowed on the French market. This is the case for the Japanese encephalitis (JE) and for the tick encephalitis (TE) of Central Europe. Details should be given about how the traveller can benefit from these vaccines, and about practical procedures to obtain them. The agents responsible are viruses transmitted by arthropods (the mosquito and the tick, respectively). The variability of the risk and the seasons of transmission, variable from one region to another (especially as far as JE is concerned), have to be taken into account. Also, the small risk of infection presently encountered and the small percentage of persons developing clinical syndromes after an infectious bite should be taken into consideration. Practically speaking, vaccination against the Japanese encephalitis is recommended to those persons who plan to stay in an endemic or epidemic region for several weeks during the season of transmission, especially if a trip into rural areas is entailed. As far as tick encephalitis is concerned, infection can take place in all rural areas (meadows, clearings, underwoods ...) of the Vosges and the zones east of them, especially in Central Europe, Russia and Siberia. While the decision is still justifiably pending as to whether to allow these vaccines on the market, it is possible to obtain from the public health administration a temporary authorization for their administration. Travellers should in any case be strongly advised to protect themselves against the bites of arthropods.

Drug and Narcotic Control↗
PubMed1997

[The elderly traveler].

An elderly traveler in good health is the same as any other traveler. However before departure elderly subjects should make sure that the proposed schedule of activities is compatible with their physical abilities. Medical counseling should be sought to determine that there are no conflicting health problems or physical impediments. Destination, itinerary, and transportation should selected accordingly. Immunization records should be checked and the main vaccination requirements for elderly subjects should be updated. To avoid running short of any prescribed mediation, an adequate supply for the whole trip must be packed. If air travel is planned, advice should be given on avoiding dehydration and thromboembolism. During his stay at the destination and especially in tropical areas, the subject should get adequate rest and guard against dehydration by drinking sufficiently, protecting against heat exposure, and controlling diarrhea promptly. Using these precautions, elderly subjects can travel as safely as possible.

Aged↗
PubMed1997

[Diabetes and travel].

With the continuing expansion in international air travel, increasing numbers of diabetic patients consult physicians for advice before going abroad. Careful planning is required taking into account climatic and medical conditions at the destination. Diabetic travelers should pack an appropriate treatment kit and contract special insurance coverage for medical evacuation. Precautions are necessary to limit the effects of motion sickness and time differences on diabetes control and especially the risk of hypoglycemia. Special attention is needed to avoid digestive problems and prevent foot injuries which can lead to serious complications in diabetic patients. Diabetic patients cannot forget their health problem during vacation and must be especially cautious when traveling. However with proper training, the risks of foreign travel can be reduced to acceptable levels.

Diabetes Complications↗
PubMed1997

[Road vehicle accidents during travel and their prevention].

The number of road vehicle accidents during travel outside Europe and/or under difficult conditions increases about 5% every year. Road accidents account for a third to half of medical evacuations as well as for the most serious injuries. The risk of accidents and their potential gravity may be enhanced by the poor condition of roads and vehicles. Personal factors including fatigue, speed, alcohol, drugs, and poor vision also play a major role. Physicians should warn travelers planning road trips of all these hazards and of any specific local conditions prevailing in certain destinations. Prevention depends on the age of the traveler and on any disabilities that he/she might have. Packing a first aid kit and inspecting safety equipment before the trip and at regular intervals during the trip are indispensable. Knowledge of emergency first aid procedures is highly recommendable. While avoiding excessiveness of any kind, the physician should encourage suitable psychological and material preparation in function of travel plans. This preparation should be aimed at reducing the risk of road accident particularly in developing countries. Counseling can be useful in reducing the risk of road accidents particularly in developing countries.

Accidents, Traffic↗
PubMed1998

[Annual epidemics of hepatitis A in four large cities related to holiday travel among immigrant children].

OBJECTIVE: Analysis of the transmission pattern of hepatitis A in relation to ethnicity and travel behaviour in Amsterdam. Utrecht, Rotterdam and The Hague. DESIGN: Descriptive study of notified cases. SETTING: Municipal Health Services of the four major cities in the Netherlands. METHOD: Notification data of hepatitis A in Amsterdam, Utrecht, Rotterdam and The Hague were analysed over the period 1992-1995. Cases were analysed according to age (0-19 years or > 19 years), whether or not they travelled abroad in the period of six weeks before the onset of the first symptoms of disease, and endemicity of hepatitis A in the country of ethnic origin. RESULTS: The strong increase of hepatitis A after the summer holidays could be divided into several smaller epidemics starting with an epidemic among children of Moroccan and Turkish descent who had spent the summer holidays in these countries, among children of the same ethnic background who had not travelled abroad, followed by epidemics among non-travelling children and adults of mainly Dutch descent, respectively. A strong correlation was found in Amsterdam between the incidence in the former two groups and the latter two groups (Pearsons r = 0.68; p = 0.004). CONCLUSION: Children who spent the summer holidays in a hepatitis A endemic country, particularly Morocco and Turkey, appeared to be the main importers of hepatitis A in the four major cities. Active immunization of all children born in the Netherlands of Moroccan and Turkish descent is the most preferable intervention.

Adolescent↗
PubMed2003

Existence of traveling wave solutions in a diffusive predator-prey model.

We establish the existence of traveling front solutions and small amplitude traveling wave train solutions for a reaction-diffusion system based on a predator-prey model with Holling type-II functional response. The traveling front solutions are equivalent to heteroclinic orbits in R(4) and the small amplitude traveling wave train solutions are equivalent to small amplitude periodic orbits in R(4). The methods used to prove the results are the shooting argument and the Hopf bifurcation theorem.

Animals↗
PubMed2007

Are buffers boring? Uniqueness and asymptotical stability of traveling wave fronts in the buffered bistable system.

Traveling waves of calcium are widely observed under the condition that the free cytosolic calcium is buffered. Thus it is of physiological interest to determine how buffers affect the properties of calcium waves. Here we summarise and extend previous results on the existence, uniqueness and stability of traveling wave solutions of the buffered bistable equation, which is the simplest possible model of the upstroke of a calcium wave. Taken together, the results show that immobile buffers do not change the existence, uniqueness or stability of the traveling wave, while mobile buffers can eliminate a traveling wave. However, if a wave exists in the latter case, it remains unique and stable.

Buffers↗
PubMed2002

Monotone travelling fronts in an age-structured reaction-diffusion model of a single species.

We consider a partially coupled diffusive population model in which the state variables represent the densities of the immature and mature population of a single species. The equation for the mature population can be considered on its own, and is a delay differential equation with a delay-dependent coefficient. For the case when the immatures are immobile, we prove that travelling wavefront solutions exist connecting the zero solution of the equation for the matures with the delay-dependent positive equilibrium state. As a perturbation of this case we then consider the case of low immature diffusivity showing that the travelling front solutions continue to persist. Our findings are contrasted with recent studies of the delayed Fisher equation. Travelling fronts of the latter are known to lose monotonicity for sufficiently large delays. In contrast, travelling fronts of our equation appear to remain monotone for all values of the delay.

Animals↗
PubMed2005

Travelling wave patterns in a model of the spinal pattern generator using spiking neurons.

The aim of this study is to produce travelling waves in a planar net of artificial spiking neurons. Provided that the parameters of the waves--frequency, wavelength and orientation--can be sufficiently controlled, such a network can serve as a model of the spinal pattern generator for swimming and terrestrial quadruped locomotion. A previous implementation using non-spiking, sigmoid neurons lacked the physiological plausibility that can only be attained using more realistic spiking neurons. Simulations were conducted using three types of spiking neuronal models. First, leaky integrate-and-fire neurons were used. Second, we introduced a phenomenological bursting neuron. And third, a canonical model neuron was implemented which could reproduce the full dynamics of the Hodgkin-Huxley neuron. The conditions necessary to produce appropriate travelling waves corresponded largely to the known anatomy and physiology of the spinal cord. Especially important features for the generation of travelling waves were the topology of the local connections--so-called off-centre connectivity--the availability of dynamic synapses and, to some extent, the availability of bursting cell types. The latter were necessary to produce stable waves at the low frequencies observed in quadruped locomotion. In general, the phenomenon of travelling waves was very robust and largely independent of the network parameters and emulated cell types.

Action Potentials↗
PubMed2002

Recent Advances and New Challenges in Travel Medicine.

Recent advances in travel medicine include the use of computer resources to obtain information on outbreaks and recommendations to travelers, the introduction of atovaquone/proguanil as chemoprophylaxis and treatment for malaria, the use of azithromycin as an alternative in the self-treatment of traveler's diarrhea, and the combination of hepatitis A and hepatitis B vaccines. At the same time, new challenges continue to appear. Shifts in the distribution of infections, such as West Nile virus and dengue fever, underscore the need for up-to-date information. Well-known infectious diseases, such as polio, meningococcal meningitis, and influenza are appearing in unexpected ways and settings. It is increasingly clear that travelers, while at risk for infections, also play a role in the global dispersal of pathogens, such as certain serogroups of Neisseria meningitidis and influenza. Increasing drug resistance affects the choice of drugs for treatment and chemoprophylaxis, and decisions about use of vaccines. Newly identified adverse events associated with yellow fever vaccine have prompted enhanced surveillance after vaccination and careful scrutiny of appropriate indications for the vaccine.

Journal Article↗
PubMed1999

Vaccination in Travelers.

Vaccination of populations throughout the world has led to dramatic decreases in morbidity and mortality from many infectious diseases, including poliomyelitis and measles. In the United States, for example, morbidity and mortality from invasive disease from Haemophilus influenzae type b has decreased more than 99%. International travelers should ensure that they are up-to-date on their routine immunizations and then consider vaccination against other diseases based on risk. This article reviews new vaccines such as those against rotavirus, Lyme disease, and enterotoxigenic Escherichia coli and provides updated information on the risk of typhoid fever and the efficacy of vaccination against it. The use of hepatitis A vaccine in outbreak control, the safety of yellow fever vaccine, and the importance of protecting travelers against rabies exposure are also discussed. Vaccination is an important way for travelers to maintain their health before, during, and after travel.

Journal Article↗
PubMed2006

Travel path conditions dictate the manner in which individuals avoid collisions.

The ability to perceive the motion of approaching objects and to make appropriate adjustments to avoid collisions is an essential component of safe locomotion through the environment. No previous study has looked at actual behavioural responses in a realistic collision avoidance task. We investigated individuals' collision avoidance behaviour with an approaching object in order to understand the visual information used to accomplish the task. We found that when individuals were walking towards a goal without any restrictions, a change in travel path occurred at the same time, independent of the object's approach velocity. However, the lateral rate of change in the travel path was significantly slower for the slower approach velocity. We found that when a restriction was present along the travel path, individuals were exposed to the object's properties for longer and a change in travel path occurred later for slowest approaching velocities than for the fastest approaching velocities. The results suggest that individuals are capable of determining TTC from an approaching object during actual self-motion, but the motor parameter it modulates is different for different circumstances.

Adult↗
PubMed2006

Travel depth, a new shape descriptor for macromolecules: application to ligand binding.

Depth is a term frequently applied to the shape and surface of macromolecules, describing for example the grooves in DNA, the shape of an enzyme active site, or the binding site for a small molecule in a protein. Yet depth is a difficult property to define rigorously in a macromolecule, and few computational tools exist to quantify this notion, to visualize it, or analyze the results. We present our notion of travel depth, simply put the physical distance a solvent molecule would have to travel from a surface point to a suitably defined reference surface. To define the reference surface, we use the limiting form of the molecular surface with increasing probe size: the convex hull. We then present a fast, robust approximation algorithm to compute travel depth to every surface point. The travel depth is useful because it works for pockets of any size and complexity. It also works for two interesting special cases. First, it works on the grooves in DNA, which are unbounded in one direction. Second, it works on the case of tunnels, that is pockets that have no "bottom", but go through the entire macromolecule. Our algorithm makes it straightforward to quantify discussions of depth when analyzing structures. High-throughput analysis of macromolecule depth is also enabled by our algorithm. This is demonstrated by analyzing a database of protein-small molecule binding pockets, and the distribution of bound magnesium ions in RNA structures. These analyses show significant, but subtle effects of depth on ligand binding localization and strength.

Algorithms↗
PubMed2006

A feminist exploration of Traveller women's experiences of maternity care in the Republic of Ireland.

OBJECTIVE: to explore Traveller women's experiences of maternity care so that their needs might be identified and perceptions of helpful responses elicited. DESIGN: feminist research methodology using unstructured non-directive interviews. SETTING: community setting in the Republic of Ireland. PARTICIPANTS: snowball sample of 13 Traveller women aged 19-42 years. Each had experienced between two and eight pregnancies. FINDINGS: a fluid concept of culture affected Traveller women's expectations and negotiation of maternity care. The essential nature of familism, socialisation and religious beliefs, and the particular emphasis placed upon peer support, reflected cohesive and supportive aspects of culture. The concept of 'possessive individualism' was portrayed as conflicting with contraceptive use, the uptake of preventive care and women's reporting of mental-health problems. Majority norm expectations of breast feeding, husband participation and 'rooming in' were culturally unacceptable. Political and structural factors, such as the direct discriminatory barriers created by general practitioner services, indirect discrimination arising from dysfunctional communication and control of information, poor housing and lack of public transport were the basic causes of inequity of access to care. IMPLICATIONS FOR PRACTICE: midwives are challenged to respond sensitively to cultural preferences, meet informational needs and act as political advocates in efforts to improve maternity care experiences for Traveller women.

Adult↗
PubMed2005

Influence of water chemistry and travel distance on bacteriophage PRD-1 transport in a sandy aquifer.

Experiments were conducted to evaluate the impact of groundwater chemistry and travel distance on the transport and fate behavior of PRD-1, a bacteriophage employed as a surrogate tracer for pathogenic enteric viruses. The experiments were conducted in the unconfined aquifer at the United States Geological Survey Cape Cod Toxic-Substances Hydrology Research Site in Falmouth, Massachusetts. The transport behavior of bromide (Br(-)) and PRD-1 were evaluated in a sewage-effluent contaminated zone and a shallower uncontaminated zone at this site. Several multilevel sampling devices located along a 13-m transect were used to collect vertically discrete samples to examine longitudinal and vertical variability of PRD-1 retardation and attenuation. The concentration of viable bacteriophage in the aqueous phase decreased greatly during the first few meters of transport. This decrease is attributed to a combination of colloid filtration (attachment) and inactivation. The removal was greater (10(-12) relative recovery) and occurred within the first meter for the uncontaminated zone, whereas it was lesser (10(-9) relative recovery) and occurred over 4m in the contaminated zone. The lesser removal observed for the contaminated zone is attributed to the influence of sorbed and dissolved organic matter, phosphate, and other anions, which are present in higher concentrations in the contaminated zone, on PRD-1 attachment. After the initial decrease, the aqueous PRD-1 concentrations remained essentially constant in both zones for the remainder of the tests (total travel distances of 13 m), irrespective of variations in geochemical properties within and between the two zones. The viable, mobile PRD-1 particles traveled at nearly the rate of bromide, which was used as a non-reactive tracer. The results of this study indicate that a small fraction of viable virus particles may persist in the aqueous phase and travel significant distances in the subsurface environment.

Bacteriophage PRD1↗
PubMed2003

Backward location and travel time probabilities for a decaying contaminant in an aquifer.

Backward location and travel time probabilities can be used to determine the prior position of contamination in an aquifer. These probabilities, which are related to adjoint states of concentration, can be used to improve characterization of known sources of groundwater contamination, to identify previously unknown contamination sources, and to delineate capture zones. The first contribution of this paper is to extend the adjoint model to the case of a decaying solute (first-order decay), and to describe two different interpretations of backward probabilities. The conventional interpretation accounts for the probability that a contaminant particle could decay before reaching the detection location. The other interpretation is conditioned on the fact that the detected contaminant particle actually reached the detection location, despite this possibility of decay. In either case, travel time probabilities are skewed toward earlier travel times, relative to a conservative solute. The second contribution of this paper is to verify the load term for a monitoring well observation. We provide examples using one-dimensional models and hypothetical aquifers. We employ an infinite domain in order to verify the monitoring well load. This new but simple one-dimensional adjoint solution can also be used to verify higher-dimensional numerical models of backward location and travel time probabilities. We employ a semi-infinite domain to illustrate the effect of decay on backward models of pumping well probabilistic capture zones. Decay causes the capture zones to fall closer to the well.

Humans↗