Influenza in travelers: epidemiology, risk, prevention, and control issues

Influenza vaccine effectiveness among Hajj pilgrims: a test-negative case-control analysis of data from different Hajj years

Background: Influenza is a common respiratory infection at Hajj. Thus, influenza vaccine is recommended for Hajj pilgrims but data on its effectiveness from a large sample are unavailable. This analysis aims to assess the effectiveness of the trivalent seasonal influenza vaccine (TIV) among Hajj pilgrims.Patients and methods: A 'test-negative' case-control analysis using data from individual studies was conducted. Included studies involved participants from Saudi Arabia, India, Australia and the United Kingdom who attended Hajj in Makkah, Saudi Arabia in different years between 2005 and 2015. Pilgrims who developed symptoms of respiratory infection during Hajj were included in these studies. Participants' vaccination histories were recorded and respiratory samples were collected to test for influenza by PCR. Vaccine effectiveness (VE) was calculated after adjusting for potential confounders.Results: A total of 1,569 pilgrims were included in this analysis. Influenza vaccine uptake was 52.2% and the attack rate of influenza was 8.2%. The estimated overall VE was 43.4% (95% CI 11.4% to 63.9%, P = 0.01). VE against a specific subtype of influenza was not significant.Conclusion: The current analysis has shown that TIV is moderately effective among Hajj pilgrims, but the vaccine uptake has been suboptimal. Power was much reduced when testing for influenza subtypes.

Immunizations

Vaccinations are a cornerstone of the pretravel consultation. The pretravel provider should assess a traveler's past medical history, planned itinerary, activities, mode of travel, and duration of stay and make appropriate vaccine recommendations. Given that domestic vaccine-preventable illnesses are more common in international travelers than are exotic or low-income nation-associated vaccine-preventable illnesses, clinicians should first ensure that travelers are current regarding routine immunizations. Additional immunizations may be indicated in some travelers. Familiarity with geographic distribution and seasonality of infectious diseases is essential. Clinicians should be cognizant of which vaccines are live, as there exist contraindications for live vaccines.

Travel to Brazil: analysis of data from the Boston Area Travel Medicine Network (BATMN) and relevance to travelers attending world cup and olympics

We describe travelers who were evaluated pre-travel to Brazil from March 2008 through July 2010 in the Boston area. Of 599 Brazil travelers, 71%, 58%, and 50% received vaccines for yellow fever (YF), typhoid, and hepatitis A, respectively. Fewer received influenza and hepatitis B vaccines (14%, 11%). A total of 60% traveled during Brazil's peak influenza season, and one fourth visited during peak dengue transmission. The 2014 World Cup and 2016 Olympics include events throughout Brazil. Travelers should seek pre-travel assessment including YF and malaria risk; travelers should be vaccinated against influenza, be up to date on other routine vaccines, and be prepared to protect themselves against mosquitoes.

The 2014 FIFA World Cup: communicable disease risks and advice for visitors to Brazil--a review from the Latin American Society for Travel Medicine (SLAMVI)

The next FIFA World Cup will be held in Brazil in June-July 2014. Around 600,000 international visitors and participants (as well over 3 million domestic travelers) are expected. This event will take place in twelve cities. This event poses specific challenges, given its size and the diversity of attendees, including the potential for the transmission of imported or endemic communicable diseases, especially those that have an increased transmission rate as a result of close human proximity, eg, seasonal influenza, measles but also tropical endemic diseases. In anticipation of increased travel, a panel of experts from the Latin American Society for Travel Medicine (SLAMVI) developed the current recommendations regarding the epidemiology and risks of the main communicable diseases in the major potential destinations, recommended immunizations and other preventives measures to be used as a basis for advice for travelers and travel medicine practitioners. Mosquito-borne infections also pose a challenge. Dengue poses a significant risk in all states, including the host cities. Vaccination against yellow fever is recommended except for travelers who will only visit coastal areas. Travelers visiting high-risk areas for malaria (Amazon) should be assessed regarding the need for chemoprophylaxis. Chikunguya fever may be a threat for Brazil, given the presence of Aedes aegypti, vector of dengue, and the possibility of travelers bringing the virus with them when attending the event. Advice on the correct timing and use of repellents and other personal protection measures is key to preventing these vector-borne infections. Other important recommendations for travelers should focus on preventing water and food-borne diseases such as hepatitis A, typhoid fever, giardiasis and traveler's diarrhea. Sexually transmitted diseases (STD) should be also mentioned and the use of condoms advocated. This review addresses pre-travel, preventive strategies to reduce the risk of acquiring communicable diseases during a mass gathering such as the World Cup and also reviews the spectrum of endemic infections in Brazil to facilitate the recognition and management of infectious diseases in travelers returning to their countries of origin.

Vaccination and Malaria Prevention among International Travelers Departing from Athens International Airport to African Destinations

Background. International travel to Africa has grown dramatically over the last decade along with an increasing need to understand the health issues for travelers. The current survey aimed to assess vaccination and malaria prevention of travelers visiting Africa. Methods. A questionnaire-based survey was conducted from of November 1, 2011 to of April 30, 2013 at Athens International Airport. Results. A total of 360 travelers were studied; 68% were men. Their mean age was 39.9 years. Previous travel to tropical countries was reported by 71.9% of them. Most frequent destination was sub-Saharan Africa (60%). Most of them traveled for ≥1 month (62%). The main reason for travel was work (39.7%). Only 47% sought pretravel consultation. Hepatitis A, typhoid, and meningococcal vaccines were administered to 49.8%, 28%, and 26.6%, respectively, and malaria chemoprophylaxis to 66.8% of those who visited sub-Saharan Africa. A history of previous travel to a tropical country, elementary level of education, and traveling for visiting friends and relatives, and for short duration were significant determinants for not pursuing pretravel consultation. Conclusions. The current survey revealed important inadequacies in vaccine and malaria prophylaxis of travelers departing to Africa. Educational tools should be developed in order to improve awareness of travelers to risk destinations.

Paediatric travel medicine: vaccines and medications

The paediatric aspects of travel medicine can be complex, and individual advice is often required. Nonetheless, children are much more likely to acquire common infections than exotic tropical diseases whilst travelling. Important exceptions are malaria and tuberculosis, which are more frequent and severe in children. Overall, travellers' diarrhoea is the most common illness affecting travellers. This review discusses vaccines and medications that may be indicated for children who are travelling overseas. It focuses on immunizations that are given as part of the routine schedule, as well as those that are more specific to travel. Malaria and travellers' diarrhoea are also discussed.

Business travelers' risk perception of infectious diseases: where are the knowledge gaps, and how serious are they?

BACKGROUND

Many studies have explored the risk perception of frequent business travelers (FBT) toward malaria. However, less is known about their knowledge of other infectious diseases. This study aimed to identify knowledge gaps by determining the risk perception of FBT toward 11 infectious diseases.

METHODS

Our retrospective web-based survey assessed the accuracy of risk perception among a defined cohort of FBT for 11 infectious diseases. We used logistic regression and the chi-square test to determine the association of risk perception with source of travel advice, demographic variables, and features of trip preparation.

RESULTS

Surveys were returned by 63% of the 608 self-registered FBT in Rijswijk, and only the 328 completed questionnaires that adhered to our inclusion criteria were used for analysis. The majority (71%) sought pre-travel health advice and used a company health source (83%). Participants seeking company travel health advice instead of external had significantly more accurate risk knowledge (p = 0.03), but more frequently overestimated typhoid risk (odds ratio = 2.03; 95% confidence interval = 1.23-3.34). While underestimation of disease risk was on average 23% more common than overestimation, HIV risk was overestimated by 75% of FBT.

CONCLUSIONS

More accurate knowledge among FBT seeking company health advice demonstrates that access to in-company travel clinics can improve risk perception. However, there is an obvious need for risk knowledge improvement, given the overall underestimation of risk. The substantial overestimation of HIV risk is probably due to both public and in-company awareness efforts. Conversely, typhoid risk overestimation was statistically associated with seeking company health advice, and therefore specifically reflects the high focus on typhoid fever within Shell's travel clinic. This study serves as a reminder that a knowledge gap toward infectious diseases besides malaria still exists. Our article will explore the future requirements for more targeted education and research among FBT in companies worldwide.

The spread of vaccine-preventable diseases by international travellers: a public-health concern

Vaccine-preventable diseases (VPDs) are costly at both the individual and societal levels. The most common VPDs recorded in travellers are enteric (typhoid or paratyphoid B) fever, acute viral hepatitis, influenza, varicella, measles, pertussis and bacterial meningitis. Travellers suffering from VPDs are frequently hospitalized, illustrating the point that VPDs are serious and expensive. Many travellers are not properly immunized before travel. In addition to individual consequences, VPDs can have public-health consequences if they are introduced or re-introduced by infected travellers returning to areas with susceptible populations. The international spread of poliomyelitis, Neisseria meningitidis serogroup W135 meningococcal infections, measles and influenza provides strong evidence of the role of international travel in the globalization of VPDs. The surveillance of the emergence, re-emergence or spread of VPDs is essential to adapt pre-travel advice and the responses to the VPD.