Journal of travel medicine最新文献

Background: In the context of ongoing debate about whether a single dose of the yellow fever (YF) vaccine provides lifelong protection, addressing key unanswered questions-such as the extent to which revaccination enhances humoral and cell-mediated immune (CMI) responses, and the true duration of immunity-is particularly important for protecting high-risk groups. This systematic review evaluated the immunogenicity of YF revaccination, to support evidence-based vaccination policies.

Methods: A systematic search in electronic databases was conducted to identify relevant studies that evaluated humoral or CMI responses following booster YF vaccination in both adults and children from endemic and non-endemic regions. Interventions included full-dose and fractional-dose YF vaccine boosters.

Results: Twenty-one studies (n = 1821 participants) were included. Revaccination temporarily enhances neutralizing antibody titres, particularly in individuals with low or undetectable baseline immunity. Long-term seropositivity remained high in most cohorts. Individuals with high baseline titres showed limited humoral response, suggesting a limited boosting effect. In terms of CMI, booster generally results in minimal activation of T-cell markers compared to primary vaccination, suggesting that revaccination primarily sustains memory responses rather than inducing new activation. In individuals with low baseline immunity, it restores both T-cell and B-cell functional memories. Memory T-cell subsets remain detectable for over 10 years. Children vaccinated at ≤ 2 years and immunocompromised individuals showed marked benefits from revaccination.

Conclusions: Routine YF revaccination appears unnecessary for most immunocompetent individuals across different age groups given durable protection conferred by a single dose. However, booster doses may benefit specific high-risk groups such as individuals vaccinated at very young ages, those with low baseline immunity or with altered immunocompetence.

Background: Tick-borne encephalitis (TBE) is a potentially life-threatening infectious disease caused by the tick-borne encephalitis virus (TBEV). In recent years, TBE-endemic areas have expanded in Europe and the incidence of surveillance-reported TBE cases has increased. TBE is preventable through vaccination, with vaccines available and recommended for residents of, and travellers to, TBE-endemic regions. We summarized the published literature on international travel-associated TBE cases and country-specific TBE vaccine recommendations for travellers.

Methods: We conducted a systematic literature review using PubMed and Web of Science and reviewed public health surveillance online sources to identify reports of travel-associated TBE cases published from 1978 to 2024. We also analysed the European Centre for Disease Prevention and Control (ECDC) TBE Annual Epidemiological Reports from 2015 to 2022 for travel-associated cases and collected information on TBE vaccination recommendations by national public health authorities for travellers to Europe.

Results: Thirty-nine international travel-associated TBE cases were identified from 24 articles and one public health report. Of the 34 travel-associated TBE cases with clinical information, 33 (97.0%) were hospitalized for a median of 9 days. Travel-associated cases departed from the USA, Israel and several countries in Europe; the most frequently visited countries were Austria, Russia, Sweden and Switzerland. Of the 22 191 surveillance-reported TBE cases reported to ECDC from 2015 to 2022, 376 (1.7%) were international travel-associated cases. Recommendations for TBE vaccination for travellers were identified in 32 countries.

Conclusions: Despite recommendations for TBE vaccination for travellers to TBE-endemic areas in Europe, international travel-associated TBE cases among travellers to Europe continue to occur. Most of the published travel-associated TBE cases are associated with severe clinical illness. When considering the increasing geographic spread of the TBE-endemic areas and increasing TBE incidence in Europe, enhanced efforts are needed to inform appropriate international travellers about the risk of TBE and to promote vaccination of travellers to TBE-endemic areas in Europe.

Background: Although there is a rising trend in both dengue cases and immunocompromised conditions, there is limited research on how common severe dengue is in immunocompromised individuals. This data is key for those advising the ever-increasing numbers of immunocompromised travellers.

Methods: We conducted a systematic review and meta-analysis of studies reporting dengue frequency or outcomes in immunocompromised populations. Non-human and review articles were excluded. Risk of bias was assessed using the ROBINS-E tool.

Results: Eighty-five studies were included; 63 had a very high risk of bias. Frequency of dengue among different immunocompromised patient cohorts varied from 0.3% to 6.3%. Of 1182 dengue cases, 664 had autoimmune diseases, 388 were post-solid organ transplant (SOT), 20 post-stem cell transplant (HSCT), 28 had haematological malignancies, 24 non-haematological malignancies and 58 were HIV-positive. Severe dengue and mortality were estimated at 0.27 [0.22-0.33] and 0.14 [0.10-0.18], decreasing to 0.16 [0.09-0.27] and 0.04 [0.03-0.05] when very high risk or small-sample studies were excluded. Twenty-three (5.6%) of post-transplant dengue patients were considered as donor-related. Mortality reached 66.7% in HSCT and 10% in SOT. Dengue RNA was detectable up to four months in blood and up to two years in urine; viable virus was isolated from urine at nine months.

Conclusions: Dengue in immunocompromised, especially HSCT, is associated with high severity and mortality. It also has the potential for prolonged viral persistence.

Background: The intestinal microbiome influences health through communication with the brain, the immune system and gut. Travel exposes people to a different microbes and enteric pathogens that can affect health of the traveller and family that continue beyond the journey.

Methods: PubMed was searched for microbiome changes, travellers' diarrhoea, acquisition of Enterobacteriaceae and multi-drug-resistant (MDR) microbiota during international travel.

Results: When days are shortened during long-haul travel east and diet composition and timing are changed the gut microbiome experiences its first challenge. Then if travel leads people into developing regions of Latin America, Africa and Southern- and Southeastern-Asia the composition of their microbiome undergoes further changes from a different diet, stress of a chaotic schedule, change in baseline exercise and exposure to proinflammatory or frankly pathogenic microbes. Reduction in diversity of the community of species (β-diversity), results in dysbiosis and colonization by pro-inflammatory Enterobacteriaceae (Esherichia coli or Klebsiella). Development of traveller's diarrhoea is a major event leading a reduced diversity of the intestinal microbiota (dysbiosis) and carriage of multiple drug resistance (MDR) enteric bacteria that can persist and spread to family and community upon returning home. A list of preventive measures travellers should be encouraged to follow during travel to high-risk regions of the world to help maintain a strong microbiome and to prevent diarrhoea and carriage of proinflammatory and resistant bacteria that damage microbiome health is provided.

Conclusions: Future travellers should be forewarned about the hazards of international travel to their gut health, have an appreciation for safe and unsafe foods and have a plan for therapy should they develop diarrhoea. Additionally, international travel in the past year should be part of the medical history for patients developing an endogenous infection (e.g. urinary tract infection, sepsis of uncertain origin or a post-operative infection) as it may influence therapy.

A 24-year-old Swiss medical student with an extensive travel history presented to the general practitioner with solitary erythematous migratory swellings on her lower leg. A diagnosis was finally reached after 6 months, when a creeping eruption presented on her eyelid.