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.

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.

Multiple paternity in Ixodes ricinus (Acari: Ixodidae), assessed by microsatellite markers.

This investigation examines multiple paternity in Ixodes ricinus (Acari: Ixodidae). Previous studies have shown that multiple mating occurs in this tick, but this is the first evaluation of multiple paternity. Three family groups were examined by a panel of polymorphic microsatellite loci; all ticks were bred from wild-collected engorged females with a copulating male attached. For most larvae, the attached males could be excluded as possible sire, and in the 3 tested families, at least 2 of 3 females mated successfully with more than 1 male. This finding suggests that multiple paternity is a common reproductive strategy in I. ricinus, which may have consequences for the ticks' dispersal success by increasing the genetic diversity in broods from single females colonizing new sites.

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.

[Histoplasmosis among travellers to Central America]. / Histoplasmose blant reisende til Mellom-Amerika.

BACKGROUND: In April 2004, the Norwegian Institute of Public Health was notified about an outbreak of a respiratory illness among participants on a cultural-historical theme tour to Central America. One patient was examined in a Swedish hospital where the clinician suspected histoplasmosis, which later was verified by serology and by culture of Histoplasma capsulatum. In order to describe the outbreak and identify the possible source of infection, a clinical and epidemiological study was conducted. MATERIAL AND METHODS: A questionnaire on symptoms, treatment and participation in various activities was sent to all the tour participants. Reminders were sent by e-mail. In addition, some participants underwent a more detailed clinical examination. RESULTS: 19 of the 21 travellers completed the questionnaire. All travellers had visited several caves inhabited by bats in El Salvador and Guatemala. During the last 10 days of the journey, 16 of the respondents (84%) acquired a respiratory illness that lasted for more than 3 weeks. The diagnosis was confirmed by serology in 8 of the 14 tested cases. Antibacterial therapy was given to 11 patients and antifungal therapy to 3 patients. Only one patient was hospitalised. INTERPRETATION: The described outbreak of histoplasmosis was probably caused by exposure to Histoplasma capsulatum during a visit in bat-infested caves. Due to the increasing popularity of adventure and theme travels, this disease may become more frequent in our population. The condition should be considered in travellers with prolonged respiratory illness after visits to caves or other closed environments with little circulation of air that are potentially contaminated with bat or bird droppings. Persons with immunosuppression may develop severe illness, and should consider avoiding places with increased risk.

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.

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.

African tick bite fever in travelers to rural sub-Equatorial Africa.

To estimate the incidence of, identify risk factors for, and describe the clinical presentation of travel-associated African tick bite fever (ATBF), a rapidly emerging disease in travel medicine, we prospectively studied a cohort of 940 travelers to rural sub-Equatorial Africa. Diagnosis was based on suicide polymerase chain reaction and the detection of specific antibodies to Rickettia africae in serum samples by multiple-antigen microimmunofluorescence assay, Western blotting, and cross-adsorption assays. Thirty-eight travelers, 4.0% of the cohort and 26.6% of those reporting flulike symptoms, had ATBF diagnosed. More than 80% of the patients had fever, headache, and/or myalgia, whereas specific clinical features such as inoculation eschars, lymphadenitis, cutaneous rash, and aphthous stomatitis were seen in < or = 50% of patients. Game hunting, travel to southern Africa, and travel during November through April were found to be independent risk factors. Our study suggests that ATBF is not uncommon in travelers to rural sub-Saharan Africa and that many cases have a nonspecific presentation.