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Background Children frequently travel internationally. Health-related data on such children are limited. We sought to investigate the demographics, health characteristics, and preventive interventions of outbound US international pediatric travelers. Methods We analyzed data from 32 099 travelers presenting for pre-travel healthcare at the Global TravEpiNet (GTEN), a national consortium of 19 travel clinics, from January 1, 2009 to June 6, 2012. Results A total of 3332 (10%) of all GTEN travelers were children (<18 years of age). These children traveled mostly for leisure (36%) or to visit friends or relatives (VFR) (36%). Most popular destination regions were Africa (41%), Southeast Asia (16%), Central America (16%), and the Caribbean (16%). Compared with children traveling for leisure, VFR children were more likely to present <14 days before departure for pre-travel consultation (44% vs 28%), intended to travel for 28 days or longer (70% vs 22%), and to travel to Africa (62% vs 32%). Nearly half of the pediatric travelers (46%) received at least 1 routine vaccine, and most (83%) received at least 1 travel-related vaccine. Parents or guardians of one third of the children (30%) refused at least 1 recommended travel-related vaccine. Most pediatric travelers visiting a malaria-endemic country (72%) received a prescription for malaria chemoprophylaxis. Conclusions Ten percent of travelers seeking pre-travel healthcare at GTEN sites are children. VFR-travel, pre-travel consultation close to time of departure, and refusal of recommended vaccines may place children at risk for travel-associated illness. Strategies to engage pediatric travelers in timely, pre-travel care and improve acceptance of pre-travel healthcare interventions are needed. [ABSTRACT FROM PUBLISHER]

Rationale for review This review aims to summarize the transmission patterns of influenza, its seasonality in different parts of the globe, air travel- and cruise ship-related influenza infections and interventions to reduce transmission. Key findings The seasonality of influenza varies globally, with peak periods occurring mainly between October and April in the northern hemisphere (NH) and between April and October in the southern hemisphere (SH) in temperate climate zones. However, influenza seasonality is significantly more variable in the tropics. Influenza is one of the most common travel-related, vaccine-preventable diseases and can be contracted during travel, such as during a cruise or through air travel. Additionally, travellers can come into contact with people from regions with ongoing influenza transmission. Current influenza immunization schedules in the NH and SH leave individuals susceptible during their respective spring and summer months if they travel to the other hemisphere during that time. Conclusions/recommendations The differences in influenza seasonality between hemispheres have substantial implications for the effectiveness of influenza vaccination of travellers. Health care providers should be aware of influenza activity when patients report travel plans, and they should provide alerts and advise on prevention, diagnostic and treatment options. To mitigate the risk of travel-related influenza, interventions include antivirals for self-treatment (in combination with the use of rapid self-tests), extending the shelf life of influenza vaccines to enable immunization during the summer months for international travellers and allowing access to the influenza vaccine used in the opposite hemisphere as a travel-related vaccine. With the currently available vaccines, the most important preventive measure involves optimizing the seasonal influenza vaccination. It is also imperative that influenza is recognized as a travel-related illness among both travellers and health care professionals. [ABSTRACT FROM AUTHOR]

Background Measles importations and the subsequent spread from US travelers returning from abroad are responsible for most measles cases in the United States. Increasing measles-mumps-rubella (MMR) vaccination among departing US travelers could reduce the clinical impact and costs of measles in the United States. Methods We designed a decision tree to evaluate MMR vaccination at a pretravel health encounter (PHE), compared with no encounter. We derived input parameters from Global TravEpiNet data and literature. We quantified Riskexposure to measles while traveling and the average number of US-acquired cases and contacts due to a measles importation. In sensitivity analyses, we examined the impact of destination-specific Riskexposure, including hot spots with active measles outbreaks; the percentage of previously-unvaccinated travelers; and the percentage of travelers returning to US communities with heterogeneous MMR coverage. Results The no-encounter strategy projected 22 imported and 66 US-acquired measles cases, costing $14.8M per 10M travelers. The PHE strategy projected 15 imported and 35 US-acquired cases at $190.3M per 10M travelers. PHE was not cost effective for all international travelers (incremental cost-effectiveness ratio [ICER] $4.6M/measles case averted), but offered better value (ICER <$100 000/measles case averted) or was even cost saving for travelers to hot spots, especially if travelers were previously unvaccinated or returning to US communities with heterogeneous MMR coverage. Conclusions PHEs that improve MMR vaccination among US international travelers could reduce measles cases, but are costly. The best value is for travelers with a high likelihood of measles exposure, especially if the travelers are previously unvaccinated or will return to US communities with heterogeneous MMR coverage. [ABSTRACT FROM AUTHOR]

Background: Measles outbreaks continue to occur in the United States and are mostly due to infections in returning travelers. Objective: To describe how providers assessed the measles immunity status of departing U.S. adult travelers seeking pretravel consultation and to assess reasons given for nonvaccination among those considered eligible to receive the measles, mumps, rubella (MMR) vaccine. Design: Observational study in U.S. pretravel clinics. Setting: 24 sites associated with Global TravEpiNet (GTEN), a Centers for Disease Control and Prevention–funded consortium. Patients: Adults (born in or after 1957) attending pretravel consultations at GTEN sites (2009 to 2014). Measurements: Structured questionnaire completed by traveler and provider during pretravel consultation. Results: 40 810 adult travelers were included; providers considered 6612 (16%) to be eligible for MMR vaccine at the time of pretravel consultation. Of the MMR-eligible, 3477 (53%) were not vaccinated at the visit; of these, 1689 (48%) were not vaccinated because of traveler refusal, 966 (28%) because of provider decision, and 822 (24%) because of health systems barriers. Most MMR-eligible travelers who were not vaccinated were evaluated in the South (2262 travelers [65%]) or at nonacademic centers (1777 travelers [51%]). Nonvaccination due to traveler refusal was most frequent in the South (1432 travelers [63%]) and in nonacademic centers (1178 travelers [66%]). Limitation: These estimates could underrepresent the opportunities for MMR vaccination because providers accepted verbal histories of disease and vaccination as evidence of immunity. Conclusion: Of U.S. adult travelers who presented for pretravel consultation at GTEN sites, 16% met criteria for MMR vaccination according to the provider's assessment, but fewer than half of these travelers were vaccinated. An increase in MMR vaccination of eligible U.S. adult travelers could reduce the likelihood of importation and transmission of measles virus. Primary Funding Source: Centers for Disease Control and Prevention, National Institutes of Health, and the Steve and Deborah Gorlin MGH Research Scholars Award. [ABSTRACT FROM AUTHOR]

Background: Vibrio cholerae is the cause of cholera, a severe watery diarrhea. Protection against cholera is serogroup specific. Serogroup specificity is defined by the O-specific polysaccharide (OSP) component of lipopolysaccharide (LPS). Methodology: Here we describe a conjugate vaccine for cholera prepared via squaric acid chemistry from the OSP of V. cholerae O1 Inaba strain PIC018 and a recombinant heavy chain fragment of tetanus toxin (OSP:rTTHc). We assessed a range of vaccine doses based on the OSP content of the vaccine (10-50 μg), vaccine compositions varying by molar loading ratio of OSP to rTTHc (3:1, 5:1, 10:1), effect of an adjuvant, and route of immunization. Principle Findings: Immunized mice developed prominent anti-OSP and anti-TT serum IgG responses, as well as vibriocidal antibody and memory B cell responses following intramuscular or intradermal vaccination. Mice did not develop anti-squarate responses. Intestinal lamina proprial IgA responses targeting OSP occurred following intradermal vaccination. In general, we found comparable immune responses in mice immunized with these variations, although memory B cell and vibriocidal responses were blunted in mice receiving the highest dose of vaccine (50 μg). We found no appreciable change in immune responses when the conjugate vaccine was administered in the presence or absence of immunoadjuvant alum. Administration of OSP:rTTHc resulted in 55% protective efficacy in a mouse survival cholera challenge model. Conclusion: We report development of an Inaba OSP:rTTHc conjugate vaccine that induces memory responses and protection against cholera in mice. Development of an effective cholera conjugate vaccine that induces high level and long-term immune responses against OSP would be beneficial, especially in young children who respond poorly to polysaccharide antigens. [ABSTRACT FROM AUTHOR]

Background: Protective immunity against cholera is serogroup specific. Serogroup specificity in Vibrio cholerae is determined by the O-specific polysaccharide (OSP) of lipopolysaccharide (LPS). Generally, polysaccharides are poorly immunogenic, especially in young children. Methodology: Here we report the evaluation in mice of a conjugate vaccine for cholera (OSP:TThc) made from V. cholerae O1 Ogawa O-Specific Polysaccharide–core (OSP) and recombinant tetanus toxoid heavy chain fragment (TThc). We immunized mice intramuscularly on days 0, 21, and 42 with OSP:TThc or OSP only, with or without dmLT, a non-toxigenic immunoadjuvant derived from heat labile toxin of Escherichia coli. Principal Findings: We detected significant serum IgG antibody responses targeting OSP following a single immunization in mice receiving OSP:TThc with or without adjuvant. Anti-LPS IgG responses were detected following a second immunization in these cohorts. No anti-OSP or anti-LPS IgG responses were detected at any time in animals receiving un-conjugated OSP with or without immunoadjuvant, and in animals receiving immunoadjuvant alone. Responses were highest following immunization with adjuvant. Serum anti-OSP IgM responses were detected in mice receiving OSP:TThc with or without immunoadjuvant, and in mice receiving unconjugated OSP. Serum anti-LPS IgM and vibriocidal responses were detected in all vaccine cohorts except in mice receiving immunoadjuvant alone. No significant IgA anti-OSP or anti-LPS responses developed in any group. Administration of OSP:TThc and adjuvant also induced memory B cell responses targeting OSP and resulted in 95% protective efficacy in a mouse lethality cholera challenge model. Conclusion: We describe a protectively immunogenic cholera conjugate in mice. Development of a cholera conjugate vaccine could assist in inducing long-term protective immunity, especially in young children who respond poorly to polysaccharide antigens. [ABSTRACT FROM AUTHOR]

Costs and benefits of malaria prevention are provided during domestic pretravel health consultations. Healthcare payers always, and travelers often, save money when travelers adhere to malaria recommendations and prophylactic regimens in West Africa, especially for longer durations of travel.Background. Pretravel health consultations help international travelers manage travel-related illness risks through education, vaccination, and medication. This study evaluated costs and benefits of that portion of the health consultation associated with malaria prevention provided to US travelers bound for West Africa.Methods. The estimated change in disease risk and associated costs and benefits resulting from traveler adherence to malaria chemoprophylaxis were calculated from 2 perspectives: the healthcare payer's and the traveler's. We used data from the Global TravEpiNet network of US travel clinics that collect de-identified pretravel data for international travelers. Disease risk and chemoprophylaxis effectiveness were estimated from published medical reports. Direct medical costs were obtained from the Nationwide Inpatient Sample and published literature.Results. We analyzed 1029 records from January 2009 to January 2011. Assuming full adherence to chemoprophylaxis regimens, consultations saved healthcare payers a per-traveler average of $14 (9-day trip) to $372 (30-day trip). For travelers, consultations resulted in a range of net cost of $20 (9-day trip) to a net savings of $32 (30-day trip). Differences were mostly driven by risk of malaria in the destination country.Conclusions. Our model suggests that healthcare payers save money for short- and longer-term trips, and that travelers save money for longer trips when travelers adhere to malaria recommendations and prophylactic regimens in West Africa. This is a potential incentive to healthcare payers to offer consistent pretravel preventive care to travelers. This financial benefit complements the medical benefit of reducing the risk of malaria. [ABSTRACT FROM PUBLISHER]

Background Although pediatric travelers comprise < 10% of US international travelers, they account for almost half of all measles importations among returning travelers. For travelers 1–18 years with no other evidence of measles immunity, the Advisory Committee on Immunization Practices (ACIP) recommends 2 MMR vaccine doses before departure; 1 dose is recommended for infant travelers (6 to <12 months) and does not count toward their primary immunization series. All US travelers (6 months to < 6 years) are at risk for being undervaccinated for measles because MMR is routinely given at 1 years and 4–6 years. Methods We developed a decision tree model to evaluate the clinical impact and cost per case averted of pretravel health encounters (PHE) that vaccinate MMR-eligible pediatric international travelers. We compared 2 strategies for infant (6 to < 12 months) and preschool-aged (1 to <6 years) travelers: (1) no PHE : travelers departed with baseline MMR vaccination status vs. (2) PHE : MMR-eligible travelers were offered vaccination. All simulated travelers experienced a destination-specific risk of measles exposure during travel (mean, 237exposures/10M travelers; range, 19–6,750 exposures/10M travelers); if exposed to measles, travelers were at risk of illness stratified by age and MMR vaccination status (range, 0.03–0.90). Costs include direct medical costs and lost work wages for guardians. Model outcomes included measles cases, costs, and cost per case averted. We varied inputs in sensitivity analyses. Results Compared with no PHE , PHE averted 451 measles cases at $985,000/case averted for infant travelers and 54 measles cases at $1.5 million/case averted for preschool-aged travelers (table, bottom). PHE can be cost-saving for travelers to regions with higher risk of measles exposure and if more MMR-eligible travelers are vaccinated at PHE (Figure 1). At a risk of exposure associated with European travel, PHE had better value when a measles importation led to a higher number of contacts or more US-acquired cases per importation (Figure 2). Conclusion PHE for pediatric travelers (6 months to <6 years) decreased the number of imported measles cases and saved costs, especially if targeted to travelers with higher-risk destinations, if more MMR-eligible travelers are vaccinated at PHE, or if outbreaks are larger. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]