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Biomedical subjects

D J Rogers

Publications and source records attributed to D J Rogers.

At least 37 records · Page 2Linked to original sources
PubMed2000

Fragile transmission cycles of tick-borne encephalitis virus may be disrupted by predicted climate change.

Repeated predictions that vector-borne disease prevalence will increase with global warming are usually based on univariate models. To accommodate the full range of constraints, the present-day distribution of tick-borne encephalitis virus (TBEv) was matched statistically to current climatic variables, to provide a multivariate description of present-day areas of disease risk. This was then applied to outputs of a general circulation model that predicts how climatic variables may change in the future, and future distributions of TBEv were predicted for them. The expected summer rise in temperature and decrease in moisture appears to drive the distribution of TBEv into higher-latitude and higher-altitude regions progressively through the 2020s, 2050s and 2080s. The final toe-hold in the 2080s may be confined to a small part of Scandinavia, including new foci in southern Finland. The reason for this apparent contraction of the range of TBEv is that its transmission cycles depend on a particular pattern of tick seasonal dynamics, which may be disrupted by climate change. The observed marked increase in incidence of tick-borne encephalitis in most parts of Europe since 1993 may be due to non-biological causes, such as political and sociological changes.

Animals↗
PubMed2000

Etiology of interepidemic periods of mosquito-borne disease.

Dengue viruses and malaria protozoa are of increasing global concern in public health. The diseases caused by these pathogens often show regular seasonal patterns in incidence because of the sensitivity of their mosquito vectors to climate. Between years in endemic areas, however, there can be further significant variation in case numbers for which public health systems are generally unprepared. There is an acute need for reliable predictions of within-year and between-year epidemic events. The prerequisite for developing any system of early warning is a detailed understanding of the factors involved in epidemic genesis. In this report we discuss the potential causes of the interepidemic periods in dengue hemorrhagic fever in Bangkok and of Plasmodium falciparum malaria in a highland area of western Kenya. The alternative causes are distinguished by a retrospective analysis of two unique and contemporaneous 33-year time series of epidemiological and associated meteorological data recorded at these two sites. We conclude that intrinsic population dynamics offer the most parsimonious explanation for the observed interepidemic periods of disease in these locations.

Animals↗
PubMed2000

Satellites, space, time and the African trypanosomiases.

The human and animal trypanosomiases of Africa provide unique challenges to epidemiologists because of the spatial and temporal scales over which variation in transmission takes place. This chapter describes how our descriptions of the different components of transmission, from the parasites to the affected hosts, eventually developed to include geographical dimensions. It then briefly mentions two key analytical techniques used in the application of multi-temporal remotely sensed imagery to the interpretation of field data; temporal Fourier analysis for data reduction, and a variety of discriminant analytical techniques to describe the distribution and abundance of vectors and diseases. Satellite data may be used both for biological, process-based models and for statistical descriptions of vector populations and disease transmission. Examples are given of models for the tsetse Glossina morsitans in the Yankari Game Reserve, Nigeria, and in The Gambia. In both sites the satellite derived index of Land Surface Temperature (LST) is the best correlate of monthly mortality rates and is used to drive tsetse population models. The Gambia model is then supplemented with a disease transmission component; the mean infection rates of the vectors and of local cattle are satisfactorily described by the model, as are the seasonal variations of infection in the cattle. High and low spatial resolution satellite data have been used in a number of statistical studies of land cover types and tsetse habitats. In addition multi-temporal data may be related to both the incidence and prevalence of trypanosomiasis. Analysis of past and recent animal and human trypanosomiasis data from south-east Uganda supports the suggestion of the importance of cattle as a reservoir of the human disease in this area; mean infection prevalences in both human and animal hosts rise and fall in a similar fashion over the same range of increasing vegetation index values. Monthly sleeping sickness case data from the districts and counties of south-east Uganda are analysed and often show significant correlations with local LST. Case numbers increase with LST in areas that are relatively cooler than average for this part of Uganda, but decrease with LST in areas that are on average warmer. This indicates different seasonal cycles of risk across the region, and may be related to the differing vectorial roles of the two local tsetse, G. fuscipes and G. pallidipes. Finally, the increasing pace of change, and the likelihood of new or reemerging vector-borne diseases, highlight the need for accurate and timely information on habitat changes and the impacts these will have on disease transmission. The next generation of satellites will have significantly more spectral and spatial resolution than the current satellites, and will enable us to refine both statistical and biological predictions of trypanosomiasis and other vector-borne diseases within disease early warning systems.

Africa↗
PubMed2000

Forecasting disease risk for increased epidemic preparedness in public health.

Emerging infectious diseases pose a growing threat to human populations. Many of the world's epidemic diseases (particularly those transmitted by intermediate hosts) are known to be highly sensitive to long-term changes in climate and short-term fluctuations in the weather. The application of environmental data to the study of disease offers the capability to demonstrate vector-environment relationships and potentially forecast the risk of disease outbreaks or epidemics. Accurate disease forecasting models would markedly improve epidemic prevention and control capabilities. This chapter examines the potential for epidemic forecasting and discusses the issues associated with the development of global networks for surveillance and prediction. Existing global systems for epidemic preparedness focus on disease surveillance using either expert knowledge or statistical modelling of disease activity and thresholds to identify times and areas of risk. Predictive health information systems would use monitored environmental variables, linked to a disease system, to be observed and provide prior information of outbreaks. The components and varieties of forecasting systems are discussed with selected examples, along with issues relating to further development.

Communicable Diseases↗
PubMed2000

The spatial pattern of trypanosomosis prevalence predicted with the aid of satellite imagery.

Information on the spatial pattern of African animal trypanosomosis forms a prerequisite for rational disease management, but few data exist for any country in the continent. The present study describes a raster or grid-based Geographic Information System for Togo, a country representative of subhumid West Africa, with data layers on tsetse, trypanosomosis, animal production, agriculture and land use. The paper shows how trypanosomosis prevalence and packed cell volume (PCV) map displays may be predicted from correlations between representative field data and environmental and satellite data acquired from the National Oceanographic and Atmospheric Administration (NOAA) and Meteosat platforms. Discriminant analytical methods were used to assess the relationship between the amount of field data used and the accuracy of the predictions obtained. The accuracy of satellite derived predictions decreases from tsetse abundance to trypanosomosis prevalence to PCV value. The predictions improve when eco-climatic and epidemiological predictors are combined. In Togo, and probably elsewhere, the patterns of trypanosomosis prevalence and PCV are much influenced by animal husbandry and other anthropogenic factors. Additional predictor variables, incorporating these influences might therefore further improve the models.

Altitude↗
PubMed2000

Seasonal synchrony: the key to tick-borne encephalitis foci identified by satellite data.

A previous analysis of tick infestation patterns on rodents in Slovakia suggested that the key to the focal distribution of western-type tick-borne encephalitis virus (TBEv) in Europe is the geographically variable degree of synchrony in the seasonal activity of larval and nymphal Ixodes ricinus ticks. This prediction is here tested by examining records, from 7 different countries, of the seasonal variation in the abundance of larvae and nymphs feeding on rodents or questing on the vegetation. Larvae consistently started feeding and questing earlier in the year at sites within TBEv foci than elsewhere, so that they appeared in the spring as soon as nymphs were active. Such larval nymphal synchrony is associated with a rapid fall in ground-level temperatures from August to October as revealed by the satellite-derived index of Land Surface Temperature (LST). Likewise, of 1992 pixels sampled on a grid across Europe, the 418 that fell within TBEv foci were characterized by a higher than average rate of autumnal cooling relative to the peak midsummer LST. It is proposed that such a seasonal temperature profile may cause unfed larvae to pass the winter in quiescence, from which they emerge synchronously with nymphs in the spring.

Animals↗
PubMed2000

[Satellite data and disease transmission by vectors: the creation of maps for risk prediction].

The complex set of criteria determining the reproduction rate of infection (distribution, density, dynamics of arthropod populations, temperature, humidity...) can be estimated with far greater precision by satellite than by conventional meteorological stations. By linking a) distribution modes and type of environment and b) satellite data and rates of underlying biological processes, we have been able to elaborate two super-imposed models: one for vector populations and one for pathogenic agents. We have used such models to look at, for example, trypanosomiasis, malaria and Lyme disease.

Animals↗
PubMed1999

Lectins in drug delivery: a study of the acute local irritancy of the lectins from Solanum tuberosum and Helix pomatia.

Lectins are proteins or glycoproteins of non-immune origin capable of binding to one or more specific sugar residues. The potential for using lectins as a means of 'anchoring' a drug delivery system to the mucosal surfaces of the eye has been investigated in previous work, with the lectins from Solanum tuberosum and Helix pomatia showing particular promise. In this study the acute local dermal irritancy of these lectins, in terms of their potential to cause inflammation and tissue necrosis, was investigated. After an initial study in terminally anaesthetised animals (to ensure no gross toxicity was evident), five male New Zealand white rabbits from the same litter were briefly anaesthetised and Evans blue injected intravenously as a marker of inflammation. Sterile lectin solutions in normal saline at a range of concentrations from 50 to 500 microg ml(-1) were prepared and 50-microl volumes injected intradermally at 18 sites across a shaved area of each rabbit's back. The rabbits were then allowed to regain consciousness. There was no evidence of tissue necrosis, oedema or Evans blue infiltration with any of the lectin solutions administered. The rabbits did not display any signs of discomfort such as scratching or continued grooming throughout the experiment. Histological examination of the injection sites revealed little sign of any inflammation, such as heterophil migration, oedema or tissue damage. It was concluded that these lectins demonstrate minimal acute irritancy, and will, therefore, be taken forward for formulation and in vivo studies.

Anesthesia↗
PubMed1999

Incidence from coincidence: patterns of tick infestations on rodents facilitate transmission of tick-borne encephalitis virus.

Tick-borne encephalitis (TBE) virus has a highly focal distribution through Eurasia. Endemic cycles appear to depend on the transmission of non-systemic infections between ticks co-feeding on the same rodent hosts. The particular features of seasonal dynamics and infestation patterns of larval and nymphal Ixodes ricinus, but not Dermacentor reticulatus, from 4 regions within TBE foci in Slovakia, are such as to promote TBE virus transmission. The distributions of larvae and nymphs on their principal rodent hosts are highly aggregated and, rather than being independent, the distributions of each stage are coincident so that the same ca. 20% of hosts feed about three-quarters of both larvae and nymphs. This results in twice the number of infectible larvae feeding alongside potentially infected nymphs compared with the null hypothesis of independent distributions. Overall, co-feeding transmission under these circumstances brings the reproductive number (R0) for TBE virus to a level that accounts quantitatively for maintained endemic cycles. Essential for coincident aggregated distributions of larvae and nymphs is their synchronous seasonal activity. Preliminary comparisons support the prediction of a greater degree of coincident seasonality within recorded TBE foci than outside. This identifies the particular climatic factors that permit such patterns of tick seasonal dynamics as the primary predictors for the focal distribution of TBE.

Animals↗
PubMed1998

A galactose-specific lectin from the red marine alga Ptilota filicina.

A lectin from the red marine alga Ptilota filicina (PFL) was isolated by affinity chromatography on cross-linked guar gum. PFL agglutinated native and papain-treated human erythrocytes with preference for type O erythrocytes. The lectin was inhibited by galactose and its derivatives. The most potent inhibitors were p-Nitrophenyl-N-acetyl-alpha- and beta-D-galactosaminide. Porcine stomach mucin, bovine submaxillary gland mucin and asialo bovine mucin were also inhibitory. The M(r) of PFL, determined by gel filtration, was 56,900. SDS-PAGE gave one band with a subunit M(r) of 19,320, indicating the native protein to be a trimer of apparently identical subunits. PFL was shown to be rich in acidic and hydroxyl amino acids but low in basic amino acids. The ten N-terminal amino acids were Asx-Thr-Lys-Thr-Leu-Leu-Ala-.

Amino Acid Sequence↗
PubMed1998

From predicting mosquito habitat to malaria seasons using remotely sensed data: practice, problems and perspectives.

Remote sensing techniques are becoming increasingly important for identifying mosquito habitats, investigating malaria epidemiology and assisting malaria control. Here, Simon Hay, Bob Snow and David Rogers review the development of these techniques, from aerial photographic identification of mosquito larval habitats on the local scale through to the space-based survey of malaria risk over continental areas using increasingly sophisticated airborne and satellite-sensor technology. They indicate that previous constraints to uptake are becoming less relevant and suggest how future delays in the use of remotely sensed data in malaria control might be avoided.

Journal Article↗
PubMed1998

Medical complications associated with the use of rigid handcuffs: a pilot study.

The provision of Police Officers with an updated form of rigid handcuffs in 1992 resulted in adverse publicity with regard to the purported 'serious injuries' that these new handcuffs produced and there was a suggestion that they 'may have to be withdrawn'. However, the police appeared to appreciate the ease of application and control of the detained person that these rigid handcuffs afforded. This pilot study documents injuries to the wrist and other sites on 41 detained persons who had been placed in rigid handcuffs in one Metropolitan Police station during a 7-month period. Nearly all of the wrist injuries that were detected were minor and required no specific treatment. Nonetheless, there is a need for further research comparing the medical complications of rigid handcuffs and other handcuffs currently in use.

Journal Article↗
PubMed1998

Think drink, think drugs, think overdoses.

The police are frequently called upon to deal with people whose behaviour is disturbing the peace of other citizens. A large proportion of such people will have consumed alcohol, some will have consumed drugs and others will be suffering from mental illness. The role of the FME is to determine whether medical or psychiatric intervention is necessary for that individual. Because of the difficulty in assessing a person's mental state when they are believed to be under the influence of substances, it is commonplace for the person to be reassessed some hours after the initial assessment to enable the effect of any consumed substances to abate. However, if the toxic effects of consumed medication are not appreciated, such a delay in receiving medical care may have serious consequences. We report this case as a reminder to all forensic physicians of the clinical effects and possible grave complications associated with amitriptyline overdose. Doctors who work in custodial medicine should be alert to the possibility of an overdose of a drug with anti-muscarinic effects when confronted with a detained person who is acutely confused with clinical features suggestive of stimulant use.

Journal Article↗
PubMed1997

Domestic violence: do forensic physicians have a role?

The role of the forensic physician in domestic violence incidents in South London was investigated over a 6-month period. The aim of the study was to identify the nature of domestic violence, to determine whether the individuals involved had previously been in contact with the primary health care team or other agencies and whether direct communication between the examining forensic physician and the patient's general practitioner was of assistance to the latter. We concluded that there is a definite role for the forensic physician in documenting injuries in victims and assailants (although most were minor injuries), providing appropriate medical treatment, supplying information regarding support agencies and passing the relevant information, with the patient's consent, to the primary health care team.

Journal Article↗