Mitochondrial DNA in Ixodus ricinus (Acari: Ixodidae) on birds reflects ticks' transportation routes to Lista, Norway.

Ticks are important pathogen vectors, and large mammals and birds have the greatest potential for dispersing them. To study tick dispersal by migrating birds, we have analysed genetic variations in mitochondrial DNA control region from Ixodes ricinus from northward migrating blackbird, Turdus merula, and (European) robin, Erithacus rubecula, at the Lista Bird Observatory in southwestern Norway. We compared their genetic structure with that of resident tick populations from areas covering their expected last stop (i.e. Great Britain and Jutland, Denmark) before taking off for southern Norway, and the resident tick population at Lista. The statistical analysis showed that the I. ricinus found on blackbirds differed significantly from those found on robins, which is consistent with the birds' differential migration routes. I. ricinus from robins did not differ genetically from those flagged at Jutland, suggesting that the former mainly originate in continental Europe. Bayesian analysis indicated that most of the blackbirds caught early in the spring (i.e. before or on the 1st of April) carried ticks of a mixed origin from both Great Britain and continental Europe, while blackbirds caught later in the season carried an increasing amount of ticks acquired locally.

Can a galacto-oligosaccharide reduce the risk of traveller's diarrhoea? A placebo-controlled, randomized, double-blind study.

BACKGROUND: Diarrhoea is a common medical problem affecting travellers to Asia, Africa and Latin America. The use of prophylactic antimicrobial agents may increase the risk of contracting resistant bacteria. Findings indicate that oligosaccharides, i.e. carbohydrate chains of 3-10 monosaccharides, reduce the risk of diarrhoea. METHODS: We performed a placebo-controlled, double-blind study of a galacto-oligosaccharide, B-GOS (Bimuno®, Clasado Ltd, Milton Keynes UK), vs placebo for participants travelling to countries with a high/intermediate risk of diarrhoea for 7-15 days. The participants ingested 2.7g of B-GOS daily from 5 days prior to departure throughout the travel period, and returned a questionnaire, with a diarrhoea log, after their return. The case definition of diarrhoea was three or more loose stools per day. RESULTS: Of 523 enrolled subjects, 334 travellers managed to comply per protocol (PP), 349 followed the protocol at least until the onset of diarrhoea (conditionally evaluable, CE), and 408 followed the protocol with fewer than 5 days of deviance from the protocol (intention to treat, ITT). There was a significant reduction of diarrhoea incidence in the PP group (odds ratio = 0.56, P = 0.03), while the effect in the CE group was non-significant (OR = 0.65, P = 0.08). No significant effect was found during the first 7 days after starting with B-GOS, but from day 8 there was a significant effect in both the PP and CE groups (OR = 0.47, P = 0.02 and OR = 0.53, P = 0.03, respectively). The entire effect was seen in 1-day (i.e. self-limiting) diarrhoea (PP: OR = 0.25, P = 0.004). There was no effect on duration or the number of bowel movements during diarrhoea. The severity of diarrhoea was not affected. CONCLUSIONS: B-GOS reduces the risk of diarrhoea lasting 1 day. The protection seemed to start after a week of treatment with B-GOS. Strict compliance is crucial. The treatment is environmentally friendly and without adverse effects.

Phylogenetic Lineages and Postglacial Dispersal Dynamics Characterize the Genetic Structure of the Tick, Ixodes ricinus, in Northwest Europe.

Dispersal and gene flow are important mechanisms affecting the dynamics of vectors and their pathogens. Here, patterns of genetic diversity were analyzed in many North European populations of the tick, Ixodes ricinus. Population sites were selected within and between areas separated by geographical barriers in order to evaluate the importance of tick transportation by birds in producing genetic connectivity across open sea and mountain ranges. The phylogenetic analyses of the mitochondrial control region and the cytochrome b gene revealed two distinct clades with supported sub-clades, with three genetic lineages: GB and WNo associated with Great Britain and western Norway respectively, and Eu with a wider distribution across continental Europe in agreement with much lower efficiency of tick dispersal by birds than by large mammals. The results suggest different ancestry of I. ricinus colonizing Britain and the rest of northern Europe, possibly from different glacial refuges, while ticks from western Norway and continental Europe share a more recent common ancestry. Demographic history modeling suggests a period of strong increase in tick abundance coincident with progression of the European Neolithic culture, long after their post-glacial colonization of NW Europe.

How low an effect of a preventive measure against diarrhoea are travellers willing to pay for?: A survey of Norwegian travellers.

BACKGROUND: Traveller's diarrhoea (TD) is the most common infectious problem for travellers, and we lack effective ways of preventing it, apart from antibiotic prophylaxis. This study aims to quantify the risk reduction of a hypothetic TD vaccine Norwegian travellers are willing to pay for. METHODS: 1204 clients at Reiseklinikken responded to a questionnaire asking what level of effectiveness would be required of a hypothetical vaccine against TD costing US$65. RESULTS: 18.7% of the respondents would buy the vaccine even if it was only 20% effective. Among respondents older than 50 years, the proportion was 28.8%. CONCLUSIONS: Our findings should encourage the development of vaccines and other preventive measures against travellers' diarrhoea.

Transport of ixodid ticks and tick-borne pathogens by migratory birds.

Birds, particularly passerines, can be parasitized by Ixodid ticks, which may be infected with tick-borne pathogens, like Borrelia spp., Babesia spp., Anaplasma, Rickettsia/Coxiella, and tick-borne encephalitis virus. The prevalence of ticks on birds varies over years, season, locality and different bird species. The prevalence of ticks on different species depends mainly on the degree of feeding on the ground. In Europe, the Turdus spp., especially the blackbird, Turdus merula, appears to be most important for harboring ticks. Birds can easily cross barriers, like fences, mountains, glaciers, desserts and oceans, which would stop mammals, and they can move much faster than the wingless hosts. Birds can potentially transport tick-borne pathogens by transporting infected ticks, by being infected with tick-borne pathogens and transmit the pathogens to the ticks, and possibly act as hosts for transfer of pathogens between ticks through co-feeding. Knowledge of the bird migration routes and of the spatial distribution of tick species and tick-borne pathogens is crucial for understanding the possible impact of birds as spreaders of ticks and tick-borne pathogens. Successful colonization of new tick species or introduction of new tick-borne pathogens will depend on suitable climate, vegetation and hosts. Although it has never been demonstrated that a new tick species, or a new tick pathogen, actually has been established in a new locality after being seeded there by birds, evidence strongly suggests that this could occur.

Transport of Ixodes ricinus infected with Borrelia species to Norway by northward-migrating passerine birds.

Birds are capable of transporting ticks and, consequently, tick-borne pathogens over long distances and across geographical barriers such as oceans and deserts. The purpose of this study was to assess the prevalence of Borrelia spp. in ticks transported by birds by using PCR. A total of 9768 northward-migrating passerine birds was examined for ticks at 4 bird observatories along the southern Norwegian coast during their spring migration in 2003-2005. Two of the bird observatories were located on islands where flagging revealed very few or no ticks (Akerøya and Store Færder), while the other 2 were located in areas with established dense tick populations: an island, Jomfruland (>100 ticks per hour of flagging) and a mainland locality, Lista (40 ticks in one hour of flagging). Borrelia spp. were found in 70 (13.6%) of 513 examined Ixodes ricinus nymphs (19 B. afzelii, 38 B. garinii, two B. turdi, and 11 B. valaisiana) and in 14 (8.1%) of 172 examined I. ricinus larvae (ten B. garinii, one B. turdi, and three B. valaisiana). This report is the first to identify B. turdi in Europe. Ticks collected from birds of the genus Turdus (T. merula, T. philomelos, and T. iliacus) had a higher prevalence of Borrelia spp. than ticks from the other passerine genera. Ticks that were cofeeding with a Borrelia-infected tick had an increased probability of being infected with the same Borrelia species. Ticks collected on birds from the south-western locality Lista were less likely to have Borrelia than ticks found on birds from the other, more eastern localities. The Turdus spp. are particularly important, both because they carry many ticks per bird and because ticks carried by these species have a higher prevalence of Borrelia. This higher prevalence may be related to Borrelia infection of the birds or transmission of Borrelia through cofeeding. The prevalence of the different Borrelia species in ticks collected from migratory birds may be related to migration routes.

Transport of Babesia venatorum-infected Ixodes ricinus to Norway by northward migrating passerine birds.

BACKGROUND: Bovine babesiosis is regarded as a limited health problem for Norwegian cows, and the incidence has decreased markedly since the 1930s. Rare cases of babesiosis in splenectomised humans from infection with Babesia divergens and B.venatorum have been described. The objective of this study was to determine whether birds can introduce Babesia-infected ticks. There are between 30 and 85 million passerine birds that migrate to Norway every spring. METHODS: Passerine birds were examined for ticks at four bird observatories along the southern Norwegian coast during the spring migrations of 2003, 2004 and 2005. The presence of Babesia was detected in the nymphs of Ixodes ricinus by real-time PCR. Positive samples were confirmed using PCR, cloning and phylogenetic analyses. RESULTS: Of 512 ticks examined, real-time PCR revealed five to be positive (1.0%). Of these, four generated products that indicated the presence of Babesia spp.; each of these were confirmed to be from Babesia venatorum (EU1). Two of the four B. venatorum-positive ticks were caught from birds having an eastern migratory route (P< 0.001). CONCLUSIONS: Birds transport millions of ticks across the North Sea, the Skagerrak and the Kattegat every year. Thus, even with the low prevalence of Babesia-infected ticks, a substantial number of infected ticks will be transported into Norway each year. Therefore, there is a continuous risk for introduction of new Babesia spp. into areas where I. ricinus can survive.

Detection of Babesia divergens in southern Norway by using an immunofluorescence antibody test in cow sera.

BACKGROUND: The incidence of bovine babesiosis, caused by Babesia divergens (Apicomplexa: Piroplasmida) has decreased markedly since the 1930 s, but may re-emerge as a consequence of climate change and changes in legislation and pasturing practices. This is a potentially serious disease, with both economical and animal welfare consequences. Therefore, there is a need to survey the distribution of B. divergens. METHODS: We tested sera from 306 healthy pastured cows from 24 farms along the southern Norwegian coast by using an indirect immunofluorescence IgG antibody test (IFAT). Fractions of seropositive cows were compared by calculating 95% CI. RESULTS: The results of this test showed that 27% of the sera were positive for B. divergens antibodies. The fraction of antibody-positive sera that we detected showed a two-humped distribution, with a high fraction of positives being found in municipalities in the western and eastern parts of the study area, while the municipalities between these areas had few or no positive serum samples. CONCLUSIONS: Neither the farmers' observations nor the Norwegian Dairy Herd Recording System give an adequate picture of the distribution of bovine babesiosis. Serological testing of cows by using IFAT is a convenient way of screening for the presence of B. divergens in an area.

Tick-borne encephalitis in the age of general mobility.

The 11th meeting of the International Scientific Working Group on Tick-borne Encephalitis (ISW-TBE) was conducted under the title of, "From childhood to golden age: increased mobility - increased risk of contracting TBE?" Participants from 26 countries, including the United States of America and China, presented reports on the latest developments and trends in local TBE cases, vaccination coverage and risk factors. In particular, the situation of children and the elderly (the "golden agers") was discussed. As the current evidence suggests, the location and extension of endemic areas for TBE have changed over the last few years, along with global warming and the shift of infected ticks to higher altitudes. The increased mobility of the human population adds to the heightened exposure; outdoor activities and international travel are on the rise also, and especially, amongst the 50+ generation, who are already per se at higher risk of disease manifestation, complications and case fatality. Most Europeans travel within Europe, often without sufficient awareness of endemic areas. Only high immunization rates can ensure low disease rates in the long run. To achieve this goal, public education is the sole effective approach for raising the level of awareness. Overall, the risk of any given person to contract TBE should not be regarded as a fixed entity, but rather it must be estimated individually, on the basis of knowledge of the TBE virus endemic areas and risk factors.