Respiratory tract infections in travelers: a review of the GeoSentinel surveillance network

Travel Recommendations for Older Adults

Older age is an important factor in preparing travelers owing not only to physiologic changes and the increased probability of underlying medical conditions and prescription medications but also to immune status with regard to naturally acquired immunity versus immunization for vaccine-preventable diseases. Cardiovascular events (including myocardial infarctions and cerebrovascular accidents) account for most deaths abroad, followed by injuries. To plan for healthy travel, international travelers should be advised to seek care at least 4 to 6 weeks before departure. Travel medicine is a dynamic field because conditions worldwide are subject to rapid change. Clinicians must maintain a current base of knowledge if they will be regularly advising travelers or must set a threshold for referral to a travel medicine specialist.

Fever in returned travelers: results from the GeoSentinel Surveillance Network

BACKGROUND

Fever is a marker of potentially serious illness in returned travelers. Information about causes of fever, organized by geographic area and traveler characteristics, can facilitate timely, appropriate treatment and preventive measures.

METHODS

Using a large, multicenter database, we assessed how frequently fever is cited as a chief reason for seeking medical care among ill returned travelers. We defined the causes of fever by place of exposure and traveler characteristics.

RESULTS

Of 24,920 returned travelers seen at a GeoSentinel clinic from March 1997 through March 2006, 6957 (28%) cited fever as a chief reason for seeking care. Of patients with fever, 26% were hospitalized (compared with 3% who did not have fever); 35% had a febrile systemic illness, 15% had a febrile diarrheal disease, and 14% had fever and a respiratory illness. Malaria was the most common specific etiologic diagnosis, found in 21% of ill returned travelers with fever. Causes of fever varied by region visited and by time of presentation after travel. Ill travelers who returned from sub-Saharan Africa, south-central Asia, and Latin America whose reason for travel was visiting friends and relatives were more likely to experience fever than any other group. More than 17% of travelers with fever had a vaccine-preventable infection or falciparum malaria, which is preventable with chemoprophylaxis. Malaria accounted for 33% of the 12 deaths among febrile travelers.

CONCLUSIONS

Fever is common in ill returned travelers and often results in hospitalization. The time of presentation after travel provides important clues toward establishing a diagnosis. Preventing and promptly treating malaria, providing appropriate vaccines, and identifying ways to reach travelers whose purpose for travel is visiting friends and relatives in advance of travel can reduce the burden of travel-related illness.

Evaluation of a new point-of-care test for influenza A and B virus in travellers with influenza-like symptoms

Point-of-care (POC) tests for influenza facilitate clinical case management, and might also be helpful in the care of travellers who are at special risk for influenza infection. To evaluate influenza POC testing in travellers, a new assay, the ImmunoCard STAT! Flu A and B, was used to investigate travellers presenting with influenza-like symptoms. Influenza virus infection was diagnosed in 27 (13%) of 203 patients by influenza virus-specific PCR and viral culture. The POC test had sensitivity and specificity values of 64% and 99% for influenza A, and 67% and 100% for influenza B, respectively. Combined sensitivity and specificity were 67% and 99%, respectively, yielding positive and negative predictive values of 95%, and positive and negative likelihood ratios of 117 and 0.34, respectively. The convenient application, excellent specificity and high positive likelihood ratio of the POC test allowed rapid identification of influenza cases. However, negative test results might require confirmation by other methods because of limitations in sensitivity. Overall, influenza POC testing appeared to be a useful tool for the management of travellers with influenza-like symptoms.

Animal-associated injuries and related diseases among returned travellers: A review of the GeoSentinel Surveillance Network

BACKGROUND

Increased travel to exotic destinations around the world is escalating the risk of exposure to animal-associated injuries with a risk of acquiring rabies.

METHODS

We have examined data reported to GeoSentinel Surveillance Network to highlight characteristics of animal-associated injuries in travellers.

RESULTS

A total of 320 cases were reported from 1998 to 2005. Travellers were predominantly tourists from developed countries with median travel duration of 23 days. A pre-travel encounter was recorded in 45.0% of the cases. A significantly greater proportion of patients with animal-related injuries were female compared to other travel associated diagnosis (54.7% versus 47.4%) and were most likely patients aged <15 years (6.2% versus 2.6%). The proportionate morbidity for sustaining an animal bite was higher among travellers visiting Southeast Asia (3.9%) and the rest of Asia (2.2%) compared to Australia-New Zealand (1.9%), Africa (1.0%), Latin America (0.8%), North America (0.9%) and Europe (1.2%). Seventy-five percent of cases occurred in countries endemic for rabies. Dogs were involved in 51.3% of cases, monkeys in 21.2%, cats in 8.2%, bats in 0.7% and humans in 0.7%. The higher likelihood for animal-related injuries among female travellers was dependant on the animal species involved, with monkeys accounting for the majority of injuries. In contrast, males were more likely to be injured by dogs. Only 66.1% of all patients reported with animal-related injury received rabies post-exposure prophylaxis.

CONCLUSIONS

This data shows that animal-associated injuries are not uncommon among returned travellers presenting to GeoSentinel sites. The highest proportion of injuries was recorded in travellers to Asia, mostly in regions, which are endemic for rabies, and this had led to a requirement for PEP.

Imported infectious disease and purpose of travel, Switzerland

We evaluated the epidemiologic factors of patients seeking treatment for travel-associated illness from January 2004 through May 2005 at the University Hospital of Zurich. When comparing persons whose purpose of travel was visiting friends and relatives (VFR travelers; n = 121) with tourists and other travelers (n = 217), VFR travelers showed a distinct infectious disease and risk spectrum. VFR travelers were more likely to receive a diagnosis of malaria (adjusted odds ratio [OR] = 2.9, 95% confidence interval [CI] 1.2-7.3) or viral hepatitis (OR = 3.1, 95% CI 1.1-9) compared with other travelers but were less likely to seek pretravel advice (20% vs. 67%, p = 0.0001). However, proportionate rates of acute diarrhea were lower in VFR (173 vs. 364 per 1,000 ill returnees). Travel to sub-Saharan Africa contributed most to malaria in VFR travelers. In countries with large migrant populations, improved public health strategies are needed to reach VFR travelers.

Illness in Travelers Visiting Friends and Relatives: A Review of the GeoSentinel Surveillance Network

Travelers returning to their country of origin to visit friends and relatives (VFRs) have increased risk of travel-related health problems. We examined GeoSentinel data to compare travel characteristics and illnesses acquired by 3 groups of travelers to low-income countries: VFRs who had originally been immigrants (immigrant VFRs), VFRs who had not originally been immigrants (traveler VFRs), and tourist travelers. Immigrant VFRs were predominantly male, had a higher mean age, and disproportionately required treatment as inpatients. Only 16% of immigrant VFRs sought pretravel medical advice. Proportionately more immigrant VFRs visited sub-Saharan Africa and traveled for >30 days, whereas tourist travelers more often traveled to Asia. Systemic febrile illnesses (including malaria), nondiarrheal intestinal parasitic infections, respiratory syndromes, tuberculosis, and sexually transmitted diseases were more commonly diagnosed among immigrant VFRs, whereas acute diarrhea was comparatively less frequent. Immigrant VFRs and traveler VFRs had different demographic characteristics and types of travel-related illnesses. A greater proportion of immigrant VFRs presented with serious, potentially preventable travel-related illnesses than did tourist travelers.

Fever in travelers returning from tropical areas: prospective observational study of 613 cases hospitalised in Marseilles, France, 1999-2003

Background

Febrile travelers may pose a diagnostic challenge for Western physicians who are frequently involved in the assessment of these patients but unfamiliar with tropical diseases. Evaluation of this situation requires an understanding of the common etiologies, which are associated with the demographics of travelers and the destinations.

Methods

We conducted a 5-year prospective observational study on the etiologies of fever in travelers returning from the tropics admitted to the infectious and tropical diseases unit of a university teaching hospital in Marseilles, France.

Results

A total of 613 patients were enrolled, including 364 migrants (59.4%), 126 travelers (20.6%), 37 visitors (6%), 24 expatriates (3.9%), and 62 patients (10.1%) who could not be classified. Malaria was the most common diagnosis (75.2%), with most cases (62%) acquired by migrants from the Comoros archipelago and who had traveled to these islands to visit friends and relatives. Agents of food-borne and water-borne infections (3.9%) and respiratory tract infections (3.4%) were also frequently identified as the cause of fever. Other infections included emerging diseases such as gnathostomiasis, hepatitis E infection and rickettsial diseases, as well as common infections or exotic diseases.

Conclusions

Although we have identified here various causes of imported fever, 8.2% of the fevers remained unexplained. An improved approach to diagnosis may allow for the discovery of new diseases in travelers in the future.

Diarrhea and respiratory symptoms among travelers to Asia, Africa, and South and Central America from Scotland

Surveillance using admissions to hospital, while being useful, is a poor indicator of the real incidence of disease encountered by travelers. An alternative is self-reported illness among those who attended at a pretravel clinic prior to their travels. Estimates of incidence and risk factors were determined for attendees at a travel clinic in Scotland using a questionnaire. Analysis for risk factors was carried out for those travelers visiting countries in Africa, Asia, or South and Central America, who had traveled for 1 week or more and had returned between 1997 and 2001 (N= 4,856). Multivariate logistic regression was used to test the hypotheses that time abroad and age-group would be significant for both respiratory and diarrheal symptoms regardless of which of the three geographical areas are visited. From 2006 returned questionnaires (response rate = 41.3%), diarrhea and respiratory symptoms were reported by 44.2 and 16.8% of respondents, respectively; the incidence was significantly greater among travelers to Asia for both diarrheal (55.5%) and respiratory (23.7%) symptoms than among travelers to Africa (36.6 and 12.2%, respectively) or South and Central America (39.5 and 16.2%, respectively). For diarrhea, age was a highly significant risk factor for travelers to Asia, South and Central America, and Africa. Being a self-organized tourist/backpacker, traveling to Asia was associated with increased risk, while for Africa and South and Central America visiting family or friends was associated with a lower risk. For travelers to Asia, traveling to the Indian subcontinent was significantly associated with increased risk. The majority of travelers had an adverse event while traveling abroad, with diarrhea and respiratory conditions being especially common despite attending a travel clinic for advice prior to departure. However, the limitations of this surveillance-based strategy have highlighted the requirement for more research to understand more fully the issues of risk and incidence among travelers to high-risk destinations from Scotland.

[Influenza and travelling]

There is a risk for the traveler to acquire an exotic disease when traveling and to introduce it in non-endemic areas after returning. Influenza is a good example of such a disease. The incidence of flu in travelers is unknown. However, numerous outbreaks of flu have been reported in groups of travelers: package tours, pilgrims, elderly people, and travel by plane or cruise ships. Nowadays vaccination against flu is not recommended in travelers unless they belong to groups at risk for flu. Nonetheless vaccination against flu is difficult to apply to travelers due to problems in vaccine availability and inadequacy between vaccine strains and strains responsible for ongoing outbreaks in the opposite hemisphere. This vaccination seems important to travelers because flu may impair their vacation. In addition, it is also interesting for the community if it limits the spread of flu worldwide.

Illnesses in travelers returning from the tropics: a prospective study of 622 patients

BACKGROUND

Although between 8 and 19% of travelers consult a doctor after returning from the tropics, the full spectrum of health complaints is unknown.

METHODS

We analyzed the relative frequency of travel-associated health complaints in all travelers (immigrants returning from visiting their home countries, expatriates, business travelers, and tourists) consulting our department between November 2002 and May 2003.

RESULTS

A total of 622 patients were studied (256 women, 366 men; median age 38 yr; 45.3% tourists, 33.8% immigrants, 14.1% expatriates, 6.7% business travelers). The median duration of travel was 36.9 days. The main destinations were Africa (57.6%) and Asia (26.4%). A total of 637 diseases were diagnosed, distributed as follows: skin diseases (23.4%), gastrointestinal infections (19.1%), respiratory tract infections (11.5%), malaria (8.8%), schistosomiasis (7.2%), viral hepatitis (4.1%), urinary tract infections (3.5%), sexually transmitted infections (3.5%), tuberculosis (2.7%), dengue fever (2.5%), and others (13.8%). Malaria and intestinal tract infections accounted for 21% and 23% of diagnoses in the 257 febrile travelers, respectively. Overall, 230 diagnoses (36.1%) corresponded to imported tropical diseases, the main imported diseases being malaria, schistosomiasis, amebiasis, gastrointestinal disorders caused by intestinal nematodes, and dengue fever.

CONCLUSIONS

Tropical diseases are not the leading cause of consultation in travelers returning from the tropics. Immigrants are the travelers most at risk of common tropical diseases, with the noteworthy exceptions of dengue fever and invasive schistosomiasis.

Influenza Virus Infection in Travelers to Tropical and Subtropical Countries

BACKGROUND

Influenza outbreaks have been reported among travelers, but attack rates and incidence are unknown.

METHODS

A cohort study was conducted. Travelers to subtropical and tropical countries recruited at the University of Zurich Travel Clinic (Switzerland), January 1998 to March 2000, were investigated with pre- and posttravel assessment of hemagglutination inhibition and by questionnaire.

RESULTS

Among 1450 travelers recruited who completed questionnaires and provided serum samples before departure, 289 (19.9%) reported febrile illness during or after traveling abroad; of these, 211 (73.0%) provided paired serum samples. Additionally, paired serum samples were collected from 321 frequency-matched afebrile control subjects among the remaining 1161 subjects of the study population. Seroconversion for influenza virus infection was demonstrated in 40 (2.8%) of all travelers; 18 participants (1.2%) had a > or = 4-fold increase in antibody titers. This corresponds to an incidence of 1.0 influenza-associated events per 100 person-months abroad. Among the 211 febrile participants, 27 (12.8%) had seroconversion, 13 (6.2%) with a > or = 4-fold increase; among the 321 afebrile control subjects, 13 (4.0%) had seroconversion, 5 (1.6%) with a > or = 4-fold increase. Twenty-five seroconverters (62.5%; P = .747) acquired influenza outside of the European epidemic season. Sixteen patients (40.0%) sought medical attention either abroad or at home, and 32 (80.0%) were asymptomatic at the time of completion of the survey.

CONCLUSIONS

This survey indicates that influenza is the most frequent vaccine-preventable infection among travelers to subtropical and tropical countries. Infections occur mainly outside the domestic epidemic season, and they have a considerable impact. Pretravel vaccination should be considered for travelers to subtropical and tropical countries.

Vaccine-preventable diseases in long-term expatriates

The term "expatriates" refers to professionals and their families who live abroad for several months or years. Owing to potential prolonged exposure, and living conditions that may be closer to those of the local population, they are at higher risk of acquiring infectious diseases that are endemic in their new place of residence. They often have reduced access to medical services, putting them at higher risk of complications and more severe outcomes. Vaccination is probably one of the most effective means of preventing expatriates from acquiring endemic or epidemic diseases. Incapacitation or sickness in the field may cause serious disruption to project activities and impose an extra workload on the local team. It may also result in repatriation, with further extra direct and indirect costs for the organization. Predeparture advice and preparation, to promote risk reduction behavior, coupled with adequate support in the field are key ingredients to ensure effective and successful activities of collaborators. Institutions and organizations sending expatriates to developing countries have a clear responsibility, and it is in their own interests to promote the health of their employees working abroad.

The exercise of public health powers in an era of human rights: the particular problems of tuberculosis

Public health legislation provides powers of removal to hospital and detention in circumstances where a patient with active, infectious tuberculosis (TB) is unwilling to comply with the recommended treatment programme. However, these public health powers were drafted at a time of very different scientific understandings of the epidemiology of disease, and at a time of a very different appreciation of the balance between State paternalism and individual rights. The re-emergence of TB as a serious threat to public health in Britain, and the increasing incidence of multi-drug-resistant TB raises concerns about public health approaches to non-compliant patients. The Human Rights Act (1998) introduces into English domestic law, protections against interference with individual rights by public authorities. The Human Rights Act not only provides a new basis of challenge of the exercise of powers by a public body, but has also had implications for the development of traditional means of challenge such as judicial review and litigation for damages. The consequence is that NHS authorities and local authorities are now more vulnerable to challenge in the exercise of public health powers. Health bodies should explore all possible alternatives to detention of a patient suffering from TB. It is to be hoped that the heralded reform to public health legislation is undertaken as a priority.

Combining clinical and epidemiologic features for early recognition of SARS

Early recognition and rapid initiation of infection control precautions are currently the most important strategies for controlling severe acute respiratory syndrome (SARS). No rapid diagnostic tests currently exist that can rule out SARS among patients with febrile respiratory illnesses. Clinical features alone cannot with certainty distinguish SARS from other respiratory illnesses rapidly enough to inform early management decisions. A balanced approach to screening that allows early recognition of SARS without unnecessary isolation of patients with other respiratory illnesses will require clinicians not only to look for suggestive clinical features but also to routinely seek epidemiologic clues suggestive of SARS coronavirus exposure. Key epidemiologic risk factors include 1) exposure to settings where SARS activity is suspected or documented, or 2) in the absence of such exposure, epidemiologic linkage to other persons with pneumonia (i.e., pneumonia clusters), or 3) exposure to healthcare settings. When combined with clinical findings, these epidemiologic features provide a possible strategic framework for early recognition of SARS.