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Abstract: During the 1990s, Milan Labuda''s experimental results established a new paradigm for the study of tick-borne viruses that has since been strengthened by its demonstrated effectiveness in explaining the epidemiology of tick-borne encephalitis (TBE). This brief review summarizes the essential features of the transmission of tick-borne pathogens such as TBE virus. Leukocytes migrate between tick feeding sites, bearing infective virions and providing a transport route for the virus between co-feeding ticks independent of a systemic viraemia. Such tick-borne pathogens are thus transmitted from tick to tick via vertebrates; the ticks are the reservoirs as well as the vectors, while the vertebrate is the transient bridge. The aim is to bring the related but non-synonymous terms (co-feeding and non-systemic) to the attention of workers who use simple PCR screening to identify additional vertebrate reservoir hosts of vector-borne pathogens that are not in fact maintained in nature through systemic transmission. [Copyright &y& Elsevier]

Abstract: The seasonal risk to humans of picking up Ixodes ricinus ticks in different habitats at 3 recreational sites in the UK was assessed. A comprehensive range of vegetation types was sampled at 3-weekly intervals for 2 years, using standard blanket-dragging complemented by woollen leggings and square ‘heel flags’. Ticks were found in all vegetation types sampled, including short grass close to car parks, but highest densities were consistently found in plots with trees present. Blankets picked up the greatest number of ticks, but heel flags provided important complementary counts of the immature stages in bracken plots; they showed clearly that the decline in tick numbers on blankets in early summer was due to the seasonal growth of vegetation that lifted the blanket clear of the typical questing height, but in reality ticks remained abundant through the summer. Leggings picked up only 11% of the total nymphs and 22% of total adults counted, but this still represented a significant hazard to humans. These results should prompt a greater awareness of the fine-scale distribution of this species in relation to human activities that determines the most likely zones of contact between humans and ticks. Risk communication may then be designed accordingly. [Copyright &y& Elsevier]

Abstract: The variable, often dramatic, upsurge in tick-borne encephalitis in Central and Eastern Europe can best be understood as the result of a multi-factorial system of causes, including abiotic and biotic environmental changes, and human behaviour determined by socio-economic conditions. Many of these stem from the political transition with the end of Soviet rule. [Copyright &y& Elsevier]

Abstract: There is no doubt that all vector-borne diseases are very sensitive to climatic conditions. Many such diseases have shown marked increases in both distribution and incidence during the past few decades, just as human-induced climate change is thought to have exceeded random fluctuations. This coincidence has led to the general perception that climate change has driven disease emergence, but climate change is the inevitable backdrop for all recent events, without implying causality. Coincidence and causality can be disentangled using tick-borne encephalitis (TBE) as a test case, based on the excellent long-term data for this medically significant European disease system. Detailed analysis of climate records since 1970 has revealed abrupt temperature increases just prior to the dramatic upsurge in TBE incidence in many parts of central and eastern Europe. Furthermore, the seasonal patterns of this temperature change are such as might have favoured the transmission of TBE virus between co-feeding ticks. Nevertheless, the pattern of climate change is too uniform to explain the marked heterogeneity in the timing and degree of TBE upsurge, for example in different counties within each of the Baltic countries. Recent decreases as well as increases in TBE incidence must also be taken into account. Instead of a single cause, a network of interacting factors, acting synergistically but with differential force in space and time, would generate this epidemiological heterogeneity. From analysis of past and present events, it appears that human behavioural factors have played a more significant role than purely biological enzootic factors, although there is an explicit causal linkage from one to the other. This includes a range of abiotic and biotic environmental factors, together with human behaviour determined by socio-economic conditions. Many of the abrupt changes followed from the shift from planned to market economies with the fall of Soviet rule. Comparisons between eight countries have indeed revealed a remarkable correlation between poverty indicators and the relative degree of upsurge in TBE from 1993. Against this background of longer-term shifts in TBE incidence, sudden spikes in incidence appear to be due to exceptional weather conditions affecting people''s behaviour, which have a differential impact depending on socio-economic factors. This new perspective may also help explain the epidemiology of Crimean-Congo haemorrhagic fever around the eastern Mediterranean region, including the current exceptional epidemic in Turkey. [Copyright &y& Elsevier]

An ambitious plan to eradicate tsetse, and therefore tsetse-transmitted trypanosomiases, from Africa was launched at the 36th Organization of African Unity summit meeting (Togo, July 2000) in a bold attempt to re-focus attention on one of Africa''s greatest scourges. This plan involves the use of the sterile insect technique to achieve final eradication in areas where the fly is suppressed by more conventional methods (such as traps and targets). In this article, the current aims of this project are questioned on historical, ecological, logistical and financial grounds. [Copyright &y& Elsevier]

Climate has a significant impact on malaria incidence and we have predicted that forecast climate changes might cause some modifications to the present global distribution of malaria close to its present boundaries. However, it is quite another matter to attribute recent resurgences of malaria in the highlands of East Africa to climate change. Analyses of malaria time-series at such sites have shown that malaria incidence has increased in the absence of co-varying changes in climate. We find the widespread increase in resistance of the malaria parasite to drugs and the decrease in vector control activities to be more likely driving forces behind the malaria resurgence. [Copyright &y& Elsevier]

Summary: Tick-borne encephalitis (TBE) incidence increased markedly in the Baltics and Slovenia in the early 1990s, but then declined again in some places. Our analyses of temporal and spatial data on TBE incidence and vaccination revealed that over 1970–2005 up-take of vaccination varied in both time and space according to incidence, i.e. was apparently responsive to perceived risk. Since 1999, however, decreases in incidence in many counties within each country have far exceeded vaccination rates or immunity through natural exposure, and in Latvia and Lithuania these changes are correlated with previous incidence. Survey data on human activities in Latvia revealed that people in socio-economic groups whose behaviour put them at highest risk of exposure to ticks in forests, including people with lower education and lowest incomes, are least likely to be vaccinated. We conclude that risk avoidance through changing human behaviour has driven incidence-dependent decreases in TBE infection, but targeted vaccination campaigns could provide more secure protection. [Copyright &y& Elsevier]

The incidence of bovine tuberculosis (BTB) is increasing in Great Britain, exacerbated by the temporary suspension of herd testing in 2001 for fear of spreading the much more contagious foot and mouth disease. The transmission pathways of BTB remain poorly understood. Current hypotheses suggest the disease is introduced into susceptible herds from a wildlife reservoir (principally the Eurasian Badger) and/or from cattle purchased from infected areas, while the role of climatic factors in transmission has generally been ignored. Here, we show how remotely sensed satellite data, which provide good indicators of a variety of climatic factors, can be used to describe the distribution of BTB in Great Britain in 1997, and suggest how such data could be used to produce BTB risk maps for the future. [ABSTRACT FROM AUTHOR]

Malaria epidemics in the highlands of East Africa garner significant research attention, due, in part, to their proposed sensitivity to climate change. In a recent article, Zhou et al. claim that increases in climate variance, rather than simple increases in climate mean values, have had an important role in the resurgence of malaria epidemics in the East African highlands since the early 1980s. If proven, this would be an interesting result but we believe that the methods used do not test the hypothesis suggested. [Copyright &y& Elsevier]