Key points

Introduction

In 2011, international tourism arrivals increased by more than 4% to 982 million. An additional increase of 3%–4% was expected in 2012. Although much of the growth represents increased travel to Europe, travel to Southeast and South Asia, South America, and Africa has also increased. Fifty-one percent of travel was by air for leisure and recreation. Another 27% was for visiting friends and relatives (VFR), health, or religion. Some increases were to regions considered remote or exotic, which could pose different risks to travelers. Clinicians are expected to encounter pediatric travelers with malaria, travel-associated diarrhea, enteric fevers, and dermatoses such as cutaneous larva migrans. Although preventive measures are effective, certain at-risk populations, such as VFR travelers, are frequently unprepared and become ill.

In the assessment of the ill pediatric traveler, physicians must consider geographic, seasonal, and environmental factors and assess compliance to pretravel advice. A traveler taking an appropriate antimalarial agent as instructed is less likely to have malaria. Travelers to certain regions, such as Southeast Asia, are more likely to have dengue as the cause of their febrile illness. Travel to certain regions of southern Africa poses no risk for malaria or yellow fever.

VFR children pose a significant challenge. They tend to be younger and stay longer in high-risk and at times remote areas of developing countries. Children frequently become ill during or after travel. Children with malaria and typhoid fever are often hospitalized. A perception of low risk, a lack of access to a travel clinic or someone knowledgeable in travel medicine, refusal of medical insurance to cover pretravel care, and a lack of financial resources to purchase vaccines and prophylactic medications are among the reasons why most lack appropriate pretravel advice, antimalarial prophylaxis, or vaccinations. Many stay in family homes, which may increase their risk for acquiring certain diseases such as enteric infections. Many regions are endemic with dengue fever, yellow fever, typhoid fever, and malaria. A younger age places the child at greater risk of severe disease. In one study, 46% of VFR children were less than 5 years of age.

In a group of children whose family had visited a travel clinic for pretravel advice, diarrhea, abdominal pain, and fever were the most frequent posttravel complaints. Most episodes of illness occurred in the first 10 days of travel. In a large study of ill pediatric travelers, most had been tourists to Asia and sub-Saharan Africa or Latin America. Diarrhea (28%), dermatologic conditions, systemic febrile illnesses (23%), and respiratory conditions were most commonly reported. Travelers to sub-Saharan Africa were more likely to have malaria. Dermatologic conditions such as cutaneous larva migrans were more likely in children returning from Latin America.

This review addresses the most common infectious conditions observed among pediatric travelers. Discussion will be categorized according to presenting clinical features such as fever, diarrhea, and cutaneous conditions.

Introduction

In 2011, international tourism arrivals increased by more than 4% to 982 million. An additional increase of 3%–4% was expected in 2012. Although much of the growth represents increased travel to Europe, travel to Southeast and South Asia, South America, and Africa has also increased. Fifty-one percent of travel was by air for leisure and recreation. Another 27% was for visiting friends and relatives (VFR), health, or religion. Some increases were to regions considered remote or exotic, which could pose different risks to travelers. Clinicians are expected to encounter pediatric travelers with malaria, travel-associated diarrhea, enteric fevers, and dermatoses such as cutaneous larva migrans. Although preventive measures are effective, certain at-risk populations, such as VFR travelers, are frequently unprepared and become ill.

In the assessment of the ill pediatric traveler, physicians must consider geographic, seasonal, and environmental factors and assess compliance to pretravel advice. A traveler taking an appropriate antimalarial agent as instructed is less likely to have malaria. Travelers to certain regions, such as Southeast Asia, are more likely to have dengue as the cause of their febrile illness. Travel to certain regions of southern Africa poses no risk for malaria or yellow fever.

VFR children pose a significant challenge. They tend to be younger and stay longer in high-risk and at times remote areas of developing countries. Children frequently become ill during or after travel. Children with malaria and typhoid fever are often hospitalized. A perception of low risk, a lack of access to a travel clinic or someone knowledgeable in travel medicine, refusal of medical insurance to cover pretravel care, and a lack of financial resources to purchase vaccines and prophylactic medications are among the reasons why most lack appropriate pretravel advice, antimalarial prophylaxis, or vaccinations. Many stay in family homes, which may increase their risk for acquiring certain diseases such as enteric infections. Many regions are endemic with dengue fever, yellow fever, typhoid fever, and malaria. A younger age places the child at greater risk of severe disease. In one study, 46% of VFR children were less than 5 years of age.

In a group of children whose family had visited a travel clinic for pretravel advice, diarrhea, abdominal pain, and fever were the most frequent posttravel complaints. Most episodes of illness occurred in the first 10 days of travel. In a large study of ill pediatric travelers, most had been tourists to Asia and sub-Saharan Africa or Latin America. Diarrhea (28%), dermatologic conditions, systemic febrile illnesses (23%), and respiratory conditions were most commonly reported. Travelers to sub-Saharan Africa were more likely to have malaria. Dermatologic conditions such as cutaneous larva migrans were more likely in children returning from Latin America.

This review addresses the most common infectious conditions observed among pediatric travelers. Discussion will be categorized according to presenting clinical features such as fever, diarrhea, and cutaneous conditions.

Fever

Fever is a frequent manifestation of infection in children. Fortunately, most are mild and self-limiting and require no medical intervention. However, in a child returning from an endemic region, fever may be the initial presentation of a serious infection such as malaria, dengue, or enteric fever. Among hospitalized children returning from the tropics with febrile illnesses, diarrhea and malaria were the most common. A treatable cause was identified in only 46% of children. Eight percent of ill children returning from international travel were found to have malaria; 69% of these children required hospitalization. Most cases were caused by Plasmodium falciparum after travel to sub-Saharan Africa.

Because morbidity and mortality associated with travel to the tropics is significant, recognition and early treatment is imperative. Clinicians must differentiate between minor, self-limiting illnesses and diseases such as malaria, enteric fever, and infectious gastroenteritis. In most instances, fever will not be the only manifestation of disease. Chills, sweats, headaches, fatigue, neck pain, malaise, vomiting, diarrhea, and abdominal pain may be present and help with the clinical diagnosis. At times, clinical presentations in children will differ from those observed in adults. The well-described classical fever patterns associated with malaria in adults are rarely observed in children, in whom patterns are more erratic.

The etiologic diagnosis of a febrile illness is easier when the person traveled to an endemic area and returns to a nonendemic area. Specific incubation periods are helpful in determining a possible etiology. A too-short or too-long incubation period could eliminate some conditions. Box 1 lists diseases according to incubation period. Incubation periods of less than 14 days would support the diagnosis of malaria, dengue, and typhoid fever. Incubation periods greater than 14 days would rule out dengue. Known exposures to individuals with an infectious condition, such as measles or chickenpox, may help the clinician by providing a precise incubation period.

Plasmodium falciparum is the most common species of malaria acquired in West Africa. It has the highest morbidity and mortality. If suspected, prompt effective treatment is required.

In travelers to Southeast Asia and South and Central America, leptospirosis and dengue fever have become more common causes of undifferentiated fevers than malaria. Dengue fever was responsible for 6% of systemic febrile illnesses among ill-returning children. In the Amazon basin of Ecuador, leptospirosis was the most common cause of acute undifferentiated fever (13.2%), followed by malaria (mostly Plasmodium vivax ) at 12.5%. Rickettsial infections were also seen. Many of these conditions are indistinguishable, requiring molecular or serologic diagnostic testing.

Enteric fevers caused by Salmonella typhi or Salmonella paratyphi are rarely acquired in developed countries. Although foodborne outbreaks of typhoid fever have been reported in the United States in recent years, most cases are acquired from travel to developing countries, especially India and Pakistan. Overall, typhoid fever was responsible for only 1% of febrile illnesses among returning pediatric travelers seeking medical care. VFR children represent a large number of reported infections.

In diarrheal infections caused by nontyphoidal Salmonella spp. and Shigella spp., fever can be an associated feature. Most travel-related diarrheal infections occur in children less than 2 years, most while the person is still traveling. Prolonged disease was common, and many required hospitalization. Among ill-returned pediatric travelers, diarrheal infections represented 28% of all pediatric illnesses.

More than 30% of febrile illnesses are caused by more cosmopolitan-type infections, such as acute otitis media, pharyngitis, infectious mononucleosis, and soft tissue and urinary tract infections.

Clinical syndromes or examination findings may lead to a diagnosis. A child with a sepsis-like presentation may have a life-threatening infection like typhoid fever, meningitis, leptospirosis, or malaria. Coughing and tachypnea may represent a pneumonic process. Fever and jaundice may represent leptospirosis or hepatitis A or E. Meningismus, headache, vomiting, and photophobia, all suggest a central nervous system infection. Purpura may suggest meningococcal disease, whereas eschars and chagomas may support the diagnosis of rickettsioses or Chagas disease, respectively. The presence of lymphadenopathy, tonsillitis, and hepatosplenomegaly would suggest infectious mononucleosis. A person with fever and polyarthropathy arriving from northern Australia may have Ross River fever, but a traveler returning from an island in the Indian Ocean with the same symptoms may have Chikungunya. Box 2 provides differential diagnoses according to syndromic features.

An initial workup for fever in a returning pediatric traveler may consist of a complete blood count and differential, liver function tests, blood cultures, stool culture, urinalysis, and thick and thin smears for malaria. Serologic testing is needed to confirm dengue. Patients with a cough may require a chest film, and evidence of pneumonic infiltrates may require respiratory viral testing or sputum for gram stain and culture. Tuberculin skin testing or interferon-γ release assays may be required to confirm the diagnosis of tuberculosis in a young child with an atypical or complex disease. A stool culture may be useful in patients with diarrhea, as determined by the duration and type of symptoms; some may require testing for Clostridium difficile toxin. Examination for ova and parasites may be useful in persons with chronic diarrhea. Antigen assays for Cryptosporidium and Giardia are particularly sensitive. Individuals with complaints of pharyngitis and evidence of exudative disease would benefit from rapid streptococcal antigen assay with a backup throat culture (or polymerase chain reaction [PCR]) if necessary. Patients with symptoms suggestive of meningitis require a lumbar puncture. Some individuals may require diagnostic imaging with a computed tomography scan or magnetic resonance imaging. Joint aspiration is required for patients with suspected pyogenic septic arthritis.

Malaria

Enteric fever