Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011

Travel vaccines-priorities determined by incidence and impact

BACKGROUND

Infectious disease epidemiology is continuously shifting. While travel has been disrupted by the COVID-19 pandemic and travel-related epidemiological research experienced a pause, further shifts in vaccine-preventable diseases (VPDs) relevant for travellers have occurred.

METHODS

We conducted a literature search on the epidemiology of travel-related VPD and synthesized data for each disease with a focus on symptomatic cases and on the impact of the respective infection among travellers, considering the hospitalization rate, disease sequela and case fatality rate. We present new data and revised best estimates on the burden of VPD relevant for decisions on priorities in travel vaccines.

RESULTS

COVID-19 has emerged to be a top travel-related risk and influenza remains high in the ranking with an estimated incidence at 1% per month of travel. Dengue is another commonly encountered infection among international travellers with estimated monthly incidence of 0.5-0.8% among non-immune exposed travellers; the hospitalized proportion was 10 and 22%, respectively, according to two recent publications. With recent yellow fever outbreaks particularly in Brazil, its estimated monthly incidence has risen to >0.1%. Meanwhile, improvements in hygiene and sanitation have led to some decrease in foodborne illnesses; however, hepatitis A monthly incidence remains substantial in most developing regions (0.001-0.01%) and typhoid remains particularly high in South Asia (>0.01%). Mpox, a newly emerged disease that demonstrated worldwide spread through mass gathering and travel, cannot be quantified regarding its travel-related risk.

CONCLUSION

The data summarized may provide a tool for travel health professionals to prioritize preventive strategies for their clients against VPD. Updated assessments on incidence and impact are ever more important since new vaccines with travel indications (e.g. dengue) have been licensed or are undergoing regulatory review.

Tracking the Epidemiologic Shifts in Hepatitis A Sero-Prevalence Using Age Stratification: A Cross-Sectional Study at Jordan University Hospital

The study of hepatitis A virus (HAV) epidemiology and sero-prevalence has important public health implications. Changes in the epidemiology of hepatitis A can result in a larger pool of susceptible persons in countries with improved sanitation and hygienic conditions if vaccination is not provided. The aim of this study was to investigate the prevalence of HAV immunoglobulin G (IgG) in Jordan. In addition, we aimed to identify the potential differences in HAV sero-prevalence based on age, among other variables. We recruited the study participants at Jordan University Hospital in Amman, Jordan, during October 2020-June 2021. Assessment of participants' socio-demographic variables was done using a paper-based questionnaire. Testing for HAV IgG was based on a competitive enzyme linked immunosorbent assay (ELISA). The study population comprised 360 individuals with a median age of 18 years. The overall sero-prevalence of HAV in our study sample was 38.3%. Divided by age, the sero-prevalence of HAV was 8.2%, 12.3%, and 20.8% among individuals aged 10 years or less, 15 years or less, and 30 years or less, respectively. The estimated age at mid-population immunity was between 21 and 30 years. Besides age, individuals residing outside the Central region of Jordan had a significantly higher HAV sero-prevalence. Additionally, the use of filtered municipal water was associated with a lower sero-prevalence of HAV compared with the use of unfiltered municipal water among individuals aged 15 years or less. The results of this study suggest an intermediate to low endemicity of HAV in Jordan. An epidemiologic shift of HAV sero-prevalence with a declining rate of positivity for HAV IgG was noticed in this study. This highlights the importance of the recently introduced HAV vaccination in Jordan. Future research to evaluate the public health benefits of HAV vaccination in Jordan is recommended.

Vaccines for International Travel

The pretravel management of the international traveler should be based on risk management principles. Prevention strategies and medical interventions should be based on the itinerary, preexisting health factors, and behaviors that are unique to the traveler. A structured approach to the patient interaction provides a general framework for an efficient consultation. Vaccine-preventable diseases play an important role in travel-related illnesses, and their impact is not restricted to exotic diseases in developing countries. Therefore, an immunization encounter before travel is an ideal time to update all age-appropriate immunizations as well as providing protection against diseases that pose additional risk to travelers that may be delineated by their destinations or activities. This review focuses on indications for each travel-related vaccine together with a structured synthesis and graphics that show the geographic distribution of major travel-related diseases and highlight particularly high-risk destinations and behaviors. Dosing, route of administration, need for boosters, and possible accelerated regimens for vaccines administered prior to travel are presented. Different underlying illnesses and medications produce different levels of immunocompromise, and there is much unknown in this discipline. Recommendations regarding vaccination of immunocompromised travelers have less of an evidence base than for other categories of travelers. The review presents a structured synthesis of issues pertinent to considerations for 5 special populations of traveler: child traveler, pregnant traveler, severely immunocompromised traveler, HIV-infected traveler, and traveler with other chronic underlying disease including asplenia, diabetes, and chronic liver disease.

Travel-associated hepatitis A in Europe, 2009 to 2015

Travel to countries with high or intermediate hepatitis A virus (HAV) endemicity is a risk factor for infection in residents of countries with low HAV endemicity. Aim: The objective of this study was to estimate the risk for hepatitis A among European travellers using surveillance and travel denominator data. Methods: We retrieved hepatitis A surveillance data from 13 European Union (EU)/ European Economic Area (EEA) countries with comprehensive surveillance systems and travel denominator data from the Statistical Office of the European Union. A travel-associated case of hepatitis A was defined as any case reported as imported. Results: From 2009 to 2015, the 13 countries reported 18,839 confirmed cases of hepatitis A, of which 5,233 (27.8%) were travel-associated. Of these, 39.8% were among children younger than 15 years. The overall risk associated with travel abroad decreased over the period at an annual rate of 3.7% (95% confidence interval (CI): 0.7–2.7) from 0.70 cases per million nights in 2009 to 0.51 in 2015. The highest risk was observed in travellers to Africa (2.11 cases per million nights). Cases more likely to be reported as travel-associated were male and of younger age (< 25 years). Conclusion: Travel is still a major risk factor for HAV infection in the EU/EEA, although the risk of infection may have slightly decreased in recent years. Children younger than 15 years accounted for a large proportion of cases and should be prioritised for vaccination.

Destination specific risks of acquisition of notifiable food- and waterborne infections or sexually transmitted infections among Finnish international travellers, 1995-2015

BACKGROUND

Overnight international travels made by Finns more than doubled during 1995-2015. To estimate risks and observe trends of travel-related notifiable sexually transmitted and food- and water-borne infections (STIs and FWIs) among travellers, we analysed national reports of gonorrhoea, syphilis, hepatitis A, shigellosis, campylobacteriosis and salmonellosis cases and related them to travel statistics.

METHOD

Cases notified as travel-related to the Finnish infectious diseases register were used as numerators and overnight stays of Statistics Finland surveys as denominator. We calculated overall risks (per 100,000 travellers) and assessed trends (using regression model) in various geographic regions.

RESULTS

Of all travel-related cases during 1995-2015, 2304 were STIs and 70,929 FWIs. During 2012-2015, Asia-Oceania showed highest risk estimates for gonorrhoea (11.0; 95%CI, 9.5-13), syphilis (1.4; 0.93-2.1), salmonellosis (157; 151-164), and campylobacteriosis (135; 129-141), and Africa for hepatitis A (4.5; 2.5-7.9), and shigellosis (35; 28-43). When evaluating at country level, the highest risks of infections was found in Thailand, except for hepatitis A ranking Hungary the first. During 2000-2011, significantly decreasing trends occurred for most FWIs particularly in the European regions and for STIs in Russia-Baltics.

CONCLUSIONS

Our findings can be used in targeting pre-travel advice, which should also cover those visiting Thailand or European hepatitis A risk areas.

Changing hepatitis A epidemiology in the European Union: new challenges and opportunities

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