Imported Infections in Pediatric Travelers
Authors: Jonathan I. Singer, MD, FAAP, FACEP, Associate Program Director for Emergency Medicine, Professor of Emergency Medicine and Pediatrics, Boonshoft School of Medicine, Wright State University, Dayton, OH; and Melissa Williams, MD, Resident Physician, Emergency Medicine Residency, Boonshoft School of Medicine, Wright State University, Dayton, OH;
Peer Reviewer: James A. Wilde, MD, FAAP, Associate Professor of Emergency Medicine and Pediatrics, Director, Pediatric Emergency Medicine, Director, Georgia United against Antibiotic Resistant Disease (GUARD), Medical College of Georgia, Augusta.
For many reasons, travel by residents of industrialized and developed countries to developing countries is increasing. Travel to undeveloped countries exposes the traveler to infectious diseases that are endemic to the area visited. As more children are making these trips, it is possible for returning pediatric travelers to present with infections acquired during travel. My own awareness of this was heightened during my time spent in the emergency department at the University of Kentucky Medical Center in Lexington. In the fall of each school year, we saw several cases of malaria in the undergraduates who had spent time in developing countries the previous summer.
This article emphasizes the means to uncover the most common and important infectious diseases affecting children who present to the emergency department having recently traveled to the developing world.
—J. Stephan Stapczynski, MD, Editor
Introduction
International travel is common. In 2004, an estimated 763 million people crossed international borders.1 It was recently estimated that 50 million people from industrialized nations yearly visited developing countries. Travel to resource-poor countries carries health risks. Between 20-70% of those who travel report some type of illness in the midst of their journeys, or upon returning home. Among those afflicted, self-limited febrile events and illnesses associated with respiratory or gastrointestinal complaints predominate. Approximately 1-5% of travelers become ill enough to seek medical attention, either during or immediately after travel.2 The majority of ill travelers are adults. However, children are among those who travel, either with their parents or on school-sponsored trips. Like their adult counterparts, a substantial number of children become ill while globe trotting. The majority of their illnesses are common diseases that are found in pediatric non-travelers. These illnesses are not difficult to diagnosis, pose little health risk to the child, and constitute no public health concerns. Infrequently a child may have imported an indigenous infection from the country of travel. The communicable disease may not be life-threatening but poses concerns for public health. The last, and least common scenario, is that a child imports a life-threatening infection.
In a child with a possible imported infection, the differential diagnosis is created by two processes. First, define the major symptom complex. For example, is it gastrointestinal (with vomiting and diarrhea), respiratory (with cough), or a systemic process (with fever and chills)? Second, obtain a specific travel history to identify key possibilities of these symptoms based upon endemic diseases from the area visited.
Travel History
The travel history is the most important evaluation of a pediatric patient who presents after international travel. The travel history includes features that are routinely asked, such as exposure to contagion. And the travel history includes components that are not routinely asked. These include pursuits of intake, non-human contacts, risky behaviors, prophylactic measures, and itinerary.
Intake. The consumption of specific food, water, and other beverages may contribute to the likelihood of disease acquisition. Contaminated food confers the highest risk of infectivity for diarrheal illness. Those who eat fresh, unpeeled fruits or raw, leafy vegetables that have not been washed in chlorinated or iodinated water, and meats cooked to less than 160 degrees F are at risk for traveler's diarrhea and hemolytic uremic syndrome.3 Consumption of raw seafood predisposes to hepatitis and cholera.4 Consumption of unpasteurized dairy products predisposes to tuberculosis and brucellosis. Consumption of food items from open markets or street stands is a risk for the acquisition of bacterial enteric pathogens.5 An individual's water source during international travel is a significant concern. Infectious pathogens that originate in human waste or agricultural runoff contaminate water. Water sources in most developing countries are contaminated. Unboiled or untreated tap water can transmit infectious gastroenteritis. Infection can also occur from ice cubes prepared from untreated tap water. Spring water treated with an iodine filter is protective. Untreated lake or stream water predisposes to parasitic infection, such as Giardia spp., Cryptosporidium spp., Cyclospora spp., and Entamoeba spp.6
Non-Human Contacts. There is an increased likelihood of zoonosis with greater proximity to cattle, pigs, and wild animals. Risks are greater after handling animals or sustaining bites, scratches and licks. Handling an animal carcass can lead to infections.7 Depending on the geographic locale, insect bites are appropriate vectors for significant diseases. For example, bites from an anopheles mosquito may transmit malaria. A flea bite may transmit Yersinia pestis, a sand fly may transmit Bartonella bacilliformis. A bite by a fly may include invasion of the skin by larvae. Exposure to rodent excrement or saliva may transmit hantavirus. Exposure to wild fowl and unrestrained chickens may lead to acquisition of avian flu. Diving, swimming, wading, or splashing in lakes, rivers, or freshwater streams in appropriate locales can predispose to schistosomiasis. Wading, splashing, and swimming in coastal waters can predispose to dermatologic invasion of larval forms of the sea anemone or jellyfish.
Risky Behaviors. Pediatric patients who engage in unsafe sexual practices are not immune from the plethora of venereal diseases. Those who engage in body-piercing procedures, tattooing, or acupuncture place themselves at risk for hepatitis, HIV, syphilis, malaria, visceral leishmaniasis, sleeping sickness, and Chagas disease, which have been documented to have been transmitted through contaminated needles.
Preventative Measures. The preventable measures include those that may be taken before and during travel. Before children travel to developing countries, all routine immunizations should be up-to-date. In addition to the basic immunizations, travelers to areas of the world where particular diseases are endemic need special protection. Vaccination against various infectious agents may lessen the likelihood of disease acquisition. Vaccination against yellow fever and hepatitis A and B is extremely effective. Vaccination against Japanese encephalitis, cholera, and typhoid confers approximately 70% protection. Meningococcal vaccines against serotype A, C, Y, and W-135 may prevent disease acquisition in high-risk areas.
During travel, compliance with preventative food and water counseling may need reinforcement. Lapses in personal hygiene and dietary precautions are common.8 In malaria-prone regions, ask if the patient has been outdoors at night, worn long sleeves and pants, used insect repellants including nn-diethyl-3 methylbenzamide (DEET spray), and used bed nets and window screens sprayed with permethrins. If the person has been camping, has he or she disturbed excreta or plantings? Has there been any occupation or cleaning of a previously vacant abode infested with animals?
Chemoprophylactic regimens may be taken before, during, and after travel to markedly decrease the risk of infection. A perfect example is prophylaxis against malaria. The physician needs to inquire about the degree of compliance with any chemotherapeutic regimen. Those medications taken incorrectly may not reduce specific risks for disease processes relevant to the particular area visited. Use of prophylactic antibiotics to prevent traveler's diarrhea in pediatric patients is controversial.3 Antibiotics may shorten the length of symptoms, decrease complications, and improve severity of diarrhea in association with travel. However, antibiotics use to prevent traveler's diarrhea may not be effective antimicrobials against the specific enteric bacterial pathogen encountered, and they afford no protection to other viral enteric pathogens. Loperamide, used to provide symptomatic relief in adults for traveler's diarrhea, may precipitate colonic perforation and bacteremia for children, particularly in those younger than 2 years of age. A better agent to treat diarrhea in children is bismuth salicylate, which has antimicrobial and antisecretory properties and is safe even in infants.9
Travel Itinerary. The most important risk factor for travel-related illness is the area visited. Information should be obtained about all destinations, stop-overs, and side excursions. The travel destination may be high, intermediate, or low risk for likelihood of exposure to infectious diseases. High-risk destinations include developing regions of Africa, Latin America, Asia, and the Middle East. Intermediate-risk destinations include southern Europe, Central America, South America, and the Caribbean Islands. Low-risk destinations include Canada, Australia, New Zealand, Japan, northern Europe, and the United States.10
Some infectious diseases of travelers, such as tuberculosis or hepatitis, have a worldwide distribution. Other infectious diseases are prevalent in certain climates. For example, enteric fever, dengue fever, malaria, and amebic liver disease are more prevalent among travelers to tropical regions. Within a specific country, certain locations harbor uncommon pathogens. For example, certain locations in Africa predispose travelers to yellow fever, or hemorrhagic fevers due to lassa or ebola.11
It is difficult for the emergency physician to be knowledgeable on global infectious disease patterns. Further, it is unlikely that emergency physicians would monitor geographic and temporal trends in infectious diseases, particularly those diseases that are rarities in non-travelers. Resources are available for this information in both the printed and online formats. Table 1 lists several resources for a global perspective on the spectrum and relative frequency of specific infections encountered during travel.
The second question of interest relating to travel itinerary is the duration of stay. As a rule, the more time in an endemic area, the more likely the risk of acquiring a disease. The converse is also true. For many diseases, the critical period is known. For example, acquisition of tuberculosis generally requires greater than 2-months' exposure in a region with endemic tuberculosis. The dates of arrival and departure from a specific area are also important for assessing disease likelihood. A disease state in a symptomatic patient may be ruled out by a timeframe that is outside the known incubation period. (See Table 2.) As examples for febrile and diarrheal illness, arboviral infections, the majority of rickettsial infections, and the viral hemorrhagic fevers can all be excluded if fever begins more than three weeks after the traveler's return from an endemic area. Viral and bacterial causes of diarrhea will have an onset that is acute and typically begin while a patient is still abroad. Parasitic-caused diarrhea will incite delayed symptoms after a several-week incubation period. Diarrhea beginning more than one month after return is not likely to be related to travel except in the case of schistosomiasis, which can present 4-6 weeks after exposure.2,6,12 Malaria can have a variable incubation period. Falciparum malaria generally presents within 3-6 weeks.13,14 Symptoms from infections due to Plasmodium vivax may take several months to develop. Fifty percent of travelers infected with vivax malaria begin to have symptoms within one month after their return. In approximately 2%, fever develops more than one year afterward. This is a result of prophylactic medication prolongation and dormant parasite staging.15
Past Medical History
Of all demographic data, age is the most significant host factor in attack rates for travelers. Traveling, non-breast-fed infants are at highest risk for diarrheal illness. Children younger than 3 years, because of their oral exploration and potential large inoculum, experience diarrheal disease with a greater frequency than older children and adults.16 Risk of upper respiratory tract infections is greater in the younger pediatric population. In contrast, increasing pediatric age is associated with a greater risk of developing lower respiratory tract infections.17
Beyond age, medical problems may influence infectious disease acquisition during travel. Those with asplenia, malignancies, prior transplantation, and HIV have the potential for increased morbidity from respiratory and enteric infections. Immunodeficient patients, especially those with HIV, are at increased risk for opportunistic infection acquired during travel.18 Acquisition of some of these infections enhances the progression of HIV infection.19 Current medications have a minor impact. Patients on gastric suppression therapy lose the acidity barrier that protects against infection by enteropathogens. Patients on H2 blockers have an increased risk for travel-induced enteritis. Patients treated prophylactically with antibiotics to prevent traveler's diarrhea may develop antibiotic-associated diarrhea, including secondary Clostridium difficile enteritis.
Chief Complaint
A returning traveler who seeks medical care may have a single complaint, or there may be a constellation of symptoms. The most frequent complaints that promote emergency visits for returning adult and pediatric travelers are diarrhea (30-35%), respiratory symptoms (15%) and fever with or without rash (10%).10 These three complaints are sequentially addressed below.
Diarrhea
History of Present Illness for Diarrhea. Definition. The traditional adult definition of traveler's diarrhea (TD) has two components: 1) the passage of three or more unformed stools in a single day during or immediately after travel or; 2) a single diarrheal stool, if accompanied by abdominal cramping, nausea, vomiting, tenesmus, or fever.20 Children have different defecation patterns at different ages. A more practical definition of pediatric traveler's diarrhea is the 2-fold or greater increase in loose stools lasting greater than 48-72 hours, which is preceded by travel.21
Causative Pathogens. Bacterial pathogens account for 80-85% of traveler's diarrhea in studies that attempt to recover causative agents. Enterotoxic Escherichia coli (ETEC) predominates worldwide. The incidence of ETEC is highest in Latin America and lowest in Asia.3 Salmonella spp., Shigella spp. and Campylobacter spp. are the other principal pathogens of TD.22 Campylobacter jejuni predominates in southern Asia, with high rates in Bangladesh, Thailand and Morocco.4,23 Protozoa account for approximately 10% of recognized cases of TD. The most common protozoal pathogens worldwide are Cryptosporidium spp. and Giardia spp. The incidence of these pathogens is highest in northern Asia.23 Cyclospora spp., Entamoeba spp., and Dientamoeba spp. are the other common protozoan agents. Cyclospora spp. are endemic to Nepal, Peru, Haiti, Guatemala, and Indonesia. Travelers to Mexico, South Africa, India, and Nepal have higher risks of amebiasis. Viruses account for fewer than 5% of TD cases. Rotavirus and Noroviruses predominate worldwide.
Tempo. Diarrhea caused by ETEC has an abrupt onset that may begin anytime during or after travel. In one pediatric study, the onset was typically a week after departure.24 The symptoms are of moderate severity and subside in a majority of cases within 2-7 days. Ten percent of patients, particularly children younger than 3 years of age, have a more prolonged course. The other bacterial enteropathogens have a similar onset. However, they retain a greater capacity for more intense symptoms during the acute illness. Additionally, 20% of enteroinvasive Escherichia coli (EIEC), Salmonella spp., and Campylobacter spp. cases have a duration greater than one week. Symptoms of TD from protozoan infection begin after a 1-4 week incubation period. Symptoms from parasitic infection tend to be more gradual in onset compared to bacterial pathogens and are often more variable, intermittent, and more likely to be protracted. The incubation period for TD from viral agents is 2-4 days. Their explosive symptoms resolve in 5-7 days from onset.
Stool Quality. The volume of stool passed in a short timeframe is great with Vibrio spp., rotavirus, and EIEC. All other pathogens cause mild to moderate stool water loss. Blood is commonly visualized by the patient with Yersinia spp., Campylobacter spp., and invariably with EIEC. Bloody diarrhea with a history of freshwater exposure in areas of endemic schistosomiasis, such as Africa, the Middle East, South America or Asia, should bring the blood fluke parasite to mind.6 Blood may be found microscopically with Shigella spp. and Salmonella spp. enteritis.25 Mucus in the stool is commonly seen with Shigella spp. and Yersinia spp. and infrequently with EIEC. Salmonella spp., Giardia spp., and rotavirus stools are notorious for malodor.12 The greasy, frothing, floating, and foul-smell of Giardia spp. stools result from fat malabsorption.12
Associated Symptoms. Fever is present in a majority of patients with TD from Campylobacter spp., Salmonella spp., Shigella spp., Yersinia spp., Entamoeba spp., Cryptosporidium spp., Cyclospora spp., rotavirus, and Noroviruses. Neither the height nor fluctuations in the fever course are diagnostic of a specific pathogen. Absence of fever is of greater diagnostic significance. Fever is absent with Giardia spp, ETEC, and Vibrio spp. Headache or seizure associated with TD suggests Shigella spp., rotavirus, or Noroviruses.26 Headache and myalgia may accompany Campylobacter spp. infection. Acute prostration is seen with Vibrio spp. and rotavirus. More subacute or chronic fatigue and malaise is suggestive of protozoal causes of TD, especially Cyclospora spp.12 Weight loss is also prominent with protozoal-associated TD. The weight loss may be profound with Giardia spp.12 Flatulence, belching, and bloating are synonymous with protozoal-associated TD. The absence or presence of anorexia or nausea is not diagnostic of any of the TD pathogens. Vomiting is not a discriminator. However, sudden, violent emesis prior to the diarrhea suggests a bacterial enteropathogen or rotavirus. Ab-dominal pain is common to all causes of TD. The presence of diffuse, inconstant abdominal discomfort with cramping prior to or accompanying defecation does not discriminate the cause of TD.
Physical Examination for Diarrhea. Discriminating physical findings in imported diarrheal illness are infrequent. Considerable overlap exists between the various pathogens and the patient's general appearance. The degree of dehydration will further alter general appearance and affect. Malabsorption with prolonged protozoal diarrhea may lead to reduced adipose tissue. Other skin findings rarely uncover the cause of TD. Salmonella typhi may be associated with evanescent, salmon-colored, 2-3 mm, flat, truncal, blanching macules. Patients with E. coli 0157:H7 induced-hemolytic uremia may develop petechiae. Icterus may accompany hepatitis virus infection. Besides dermatologic findings, the only other signs that narrow the differential diagnosis are abdominal findings. Right upper quadrant pain with either hepatic percussion tenderness or hepatomegaly suggests salmonellosis, amebiasis, or hepatitis. TD with right lower quadrant pain suggests inflammation of the lymph nodes surrounding the terminal ileum causing the pseudoappendicular syndrome of Yersinia spp. infection.
Laboratory Tests for Diarrhea. The decision to acquire post-travel diarrheal laboratory assessments is left to the judgment of the emergency physician. There are no absolute indications to acquire any testing. If necessary for public health considerations or cohorting during hospital admission, patients with non-bloody diarrhea can have rotavirus antigen detection of stool specimen by enzyme immunoassay or latex agglutination. There is a greater need to identify a pathogen in a selected subgroup of TD patients. (See Table 3.)
| Table 3. Post-Travel Diarrheal Laboratory Testing |
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Returning patients with acute bloody diarrhea should have rectal swabs containing feces submitted for culture. Laboratory personnel should be informed that you are seeking to isolate Salmonella spp., Shigella spp., Yersinia spp., Campylobacter spp., or Vibrio spp. Although bacteremia is rare with these organisms, isolation from blood should be attempted in hyperpyrexic, toxic, young patients (particularly < 6 months). Optional tests to establish the specific cause of an acute diarrheal illness are available through public health reference laboratories. They are not widely available in the community. These include serum and stool specimen identification by enzyme immunoassay, latex agglutination, DNA probes, or monoclonal antibodies.
Patients who have looser than normal stools with increased frequency lasting more than 14 days should have submission of fresh stool to the laboratory for direct smear examination. The sensitivity for finding ova and parasites is increased by examining three or more specimens collected every other day. Fluorescein-conjugated monoclonal antibodies to Giardia and Cryptosporidium can be used to increase the specificity of fecal microscopy for these organisms.27
Fever
History of Present Illness for Fever. Epidemiology. From 2-12% of Americans traveling internationally report a febrile illness either during their trip or upon their return.25,28
Spectrum of Illness. Pediatric febrile events in travelers are similar to febrile, non-traveling encounters. Of those with fever who seek medical attention, more than half may report an incapacitation, as defined as an inability to pursue plans. The duration of incapacitation lasts several days.29 Most febrile illnesses are not localized to any system.23 Of those with localizing findings, the distribution varies somewhat based on age of the patient, time of year, location, and duration of travel. However, the gastrointestinal, upper respiratory, lower respiratory, and genitourinary are disproportionately represented.23,30
Causative Pathogens. In 25-40% of cases a specific etiologic diagnosis is never made despite efforts to isolate an offending pathogen.23,30 A specific agent may be found in the majority of cases of undifferentiated and localizing febrile illnesses. The organisms that are seen with febrile, non-traveling pediatric patients predominate.17 As examples, rhinovirus, enterovirus, RSV, group A beta hemolytic Streptococcus, Streptococcus pneumoniae, influenza virus, and metapneumovirus are common with respiratory infections. The typical, non-traveling associated enteric pathogens are recovered in 5-14% of febrile travelers with gastrointestinal manifestations. Several less common pathogens for non-travelers occur with a greater frequency in travelers. For example, hepatitis virus is recovered in 3-6%, Mycobacterium tuberculosis in 1-2%, Epstein-Barr virus in 0.4-2% and amebic organisms in 1-2%.31 Of greatest concern is the recovery of pathogens rarely seen in non-travelers. Specific agents that are found with frequency in undifferentiated febrile illnesses of travelers are disproportionately morbid. (See Table 4.)
| Table 4. Disproportionately Morbid Causes of Undifferentiated Fever in Returning Travelers |
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Qualities of Fever. The fever pattern may on rare occasion narrow the differential diagnosis in a traveler. An abrupt onset, particularly of ≥ 40° C (hyperpyrexia) without preceding complaints supports the possibility of bloodstream invasion. This explosive rise in temperature may be seen in 75% of children afflicted with Neisseria meningitidis. Persistent fevers between 40-41° C suggest rickettsial infection. Daily temperatures that last for a week are seen with various rickettsial pathogens such as Coxiella burnetii (Q fever), R. africae (African tick bite fever), R. rickettsiae (Rocky Mountain spotted fever), and R. conorii (Mediterranean spotted fever).32 Relapsing fever patterns may also serve as clues to pathogens. Three to six days of fever followed by an asymptomatic week and relapse of the initial episode is characteristic of Borrelia spp. (epidemic relapsing fever). Dengue virus infection typically has two 1- to 5-day febrile periods separated by an afebrile interval where there is defervescence of fever for 1-2 days (saddleback fever).13 Fevers that occur at intervals of 48-72 hours highly suggest P. vivax, P. ovale, or P. malaria infections.13,14
Associated Symptoms. In the post-travel period, fever indicates an underlying infection. Several clinical attributes of infectious agents may help distinguish them from other infectious agents. Fever accompanied by prostration, abdominal pain, and diarrhea suggests typhoid.2,30 Abrupt onset of fever with a paroxysm of chills, diaphoresis, profound malaise, and severe headache is typical of malaria.30 Abrupt fever, headache, and myalgias also occur with multiple, disparate pathogens including meningococcus, ebola, hantavirus, West Nile virus, dengue, rickettsial illness, and leptospirosis. Headache due to dengue is unique. The retroorbital pain is classically intensified by lateral movement of the eyes.30 Cough should raise the concern for hantavirus, malaria, tuberculosis, Q fever, bubonic plaque, and lassa. Hemorrhagic symptoms, such as epistaxis, hematemesis, melena, or hematuria, should cause concern for ebola, lassa, dengue, and meningococcus. Neck pain, altered behavior, affect, or reasoning raise suspicion for malaria, typhoid, rickettsial illnesses, Japanese encephalitis, West Nile virus, or meningococcus.2
Physical Examination for Fever. Alterations in vital signs with febrile illnesses are common. Tachypnea and tachycardia are not specific for any pathogen. The presence of mottling of the skin or delayed capillary refilling time with threatened shock or profound shock suggests meningococcal infection, hantavirus, ebola, or dengue.33 Conjunctival injection is seen early in ebola and leptospirosis.33 Generalized lymphadenopathy occurs with malaria, typhoid, leptospirosis, dengue, and lassa fever.2,30 Splenomegaly may occur with malaria, typhoid, brucellosis and dengue.2 Rashes, when present, may help differentiate the cause of fever. Typhoid, malaria, leptospirosis and brucellosis have blanching, bright macular or maculopapular truncal eruptions. Rickettsial exanthems are also macular or maculopapular at onset. They tend to be distributed at the periphery and advance centrally. With the passage of time, malaria, dengue, and rickettsial exanthems may become petechial. Petechial eruptions or frank purpura at onset of a hyperpyrexic illness suggests meningococcus, lassa, ebola, or yellow fever.13 Icterus is seen with hepatitis, malaria, yellow fever, leptospirosis, and relapsing fever.
Laboratory Tests for Fever. Post-travel laboratory assessments of the febrile pediatric patient should be tailored to specific variables. Unselected use of labs is not recommended. The decision whether or not to pursue laboratory evaluations in an individual patient should take into account underlying patient demographics, travel characteristics, and perception of risk for serious infections based on history of present illness and physical examination. (See Table 5.) A previously healthy, immunized child who is at low risk for invasive pathogens, and who has a non-critical focus of infection should have laboratory studies ordered in a manner consistent with the practicing standard for an equivalent non-traveling, febrile patient. It is, therefore, acceptable to order no laboratory studies. The exception is for the pediatric patient who has traveled to an endemic region for malaria. Because malaria is such a frequent cause of systemic febrile illness, with or without localizing organ-systemic findings, thick and thin Giemsa-stained blood smears should be obtained. Thick smears are helpful in finding parasites, and thin smears are best for identifying individual species. Further, it is suggested that blood films be repeated in 12-24 hour intervals, at least twice, if the initial findings are negative and malaria is suspected.13,30
| Table 5. Post-Travel Febrile Illness Laboratory Testing |
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A highly febrile pediatric patient without an apparent focus of infection, who has traveled to a region of endemic agents with great morbidity or mortality, should have a laboratory battery performed. Submit cultures of blood and urine. Examine cerebrospinal fluid in circumstances of apparent central nervous system invasion. Culture stool if an examined fecal smear contains leukocytes, or if there is a history of bloody diarrhea. A chest x-ray is warranted in those younger than 1 year of age and in older patients with respiratory manifestations.34,35 Blood chemistries should include liver function studies, as raised concentrations of transaminases and bilirubin are seen in hepatitis, Q fever, malaria, dengue fever, typhus, and typhoid.13 It is optional to submit a tube of blood or cerebrospinal fluid for polymerase chain reaction or serologic antibody detection for diseases that alter immediate treatment (such as herpes simplex virus, enterovirus, or meningococcus). Blood can also be submitted for serologic tests that are ultimately important to patient care beyond the emergency department stay (such as hepatitis profiles), but are not usually available to the emergency physician determining acute patient management. A complete blood count is readily available in all emergency facilities, but the predictive ability of a CBC to discriminate the cause of an infectious encounter in a febrile returning pediatric traveler is limited. However, the complete blood count may help support a clinical suspicion of a specific infectious pathogen when the expected hematologic profiles are found. (See Table 6.)
Respiratory Disease
History of Present Illness for Respiratory Disease. Demographics. Of all the travelers who seek care during or after travel, 8-20% suffer from respiratory tract disease.17 A much larger portion of travelers, perhaps as high as 50%, experience respiratory symptoms but seek no supervised medical attention. Preschool-aged pediatric travelers are predisposed to upper respiratory tract infections manifested by rhinitis, conjunctivitis, pharyngitis, bronchiolitis, and sinusitis. School-aged travelers are at increased risk for bronchitis and pneumonia.
Causative Pathogens. The most common pathogens that cause respiratory illness have worldwide distribution. Respiratory syncytial virus, metapneumovirus, adenovirus, Mycoplasma pneumoniae, Streptococcus pneumoniae, and rhinovirus are the most common pathogens recovered in returning pediatric travelers with respiratory illness. The pediatric traveler who has been vaccinated against influenza and pneumococcus has reduced likelihood of disease acquisition while traveling. The immunocompetent, immunized pediatric traveler, if exposed to certain environments, has an increased risk of pathogenic exposure that can lead to respiratory infection. (See Table 7.) Travel to developing countries exposes pediatric patients to pathogens that are highly unusual in non-traveling pediatric patients. (See Table 8.)
| Table 7. Epidemiologic Conditions Related to Respiratory Pathogens |
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| Table 8. Pathogens Causing Pneumonia with Increased Frequency in International Travelers |
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Symptoms and Signs. Infection within the upper respiratory tract with non-travel-related pathogens and travel-related pathogens will create similar symptoms. Common non-travel and all the travel-related lower respiratory tract pathogens will create considerable overlap in symptoms. The fever pattern may be of help to distinguish malaria and Q fever. Cough that is prolonged greater than 3 weeks suggests pertussis or tuberculosis. Blood-tinged sputum suggests tuberculosis, pneumonic plague, psittacosis, tularemia, or larval helminths.36 Extrapulmonary manifestations may serve as clues. Malaise and headache are prominent with influenza, lassa, psittacosis, coccidioidomycosis, typhus, hantavirus, malaria, Q fever, and tularemia. Myalgias are prominent in anthrax, influenza, hantavirus, lassa virus, coccidioidomycosis, Legionnaires disease, tularemia, and typhus.
Palatal petechiae are characteristic of group A beta hemolytic Streptococcus. Gray pseudomembrane exudates are characteristic of diptherial pharyngeal infection. Other signs do not distinguish pathogens causing upper respiratory tract illness. Inordinate toxicity and dyspnea along with signs of multisystem involvement suggest unusual pathogens such as lassa and dengue as the cause of lower respiratory tract illness. Bronchospasm may be seen with larval helminth invasion of the alveolar spaces. Lymphadenopathy is prominent with plague, anthrax, Chlamydia spp., histoplasmosis, tularemia, and typhoid. Hepatosplenomegaly is seen with malaria, histoplasmosis and Q fever.
Laboratory Tests for Respiratory Disease. Travel does not alter the need for laboratory testing. There is no need for laboratory tests for most upper respiratory tract infections. The CDC and the American Academy of Pediatrics suggest diagnostic testing for group A beta hemolytic Streptococcus in cases of pharyngitis without accompanying cough or rhinorrhea. The non-traveling pediatric patient with fever, tachypnea, and auscultatory findings suggestive of pneumonia should have a measurement of oxygen saturation. A chest x-ray is optional to confirm the presence of pneumonia. The post-travel evaluation of the pediatric patient with pneumonia should include measurement of oxygen saturation and chest x-ray. (See Table 9.) An unusual radiographic pattern, such as effusion or cavitary lesion, or extent, such as multilobar involvement, may lead to further investigations. Hyperpyrexia, toxicity, and hypoxemia should lead to further laboratory studies that include a CBC, thick and thin and smear, chemistries, and microbiologic testing of blood. Acute serologic titers are suggested. When there has been significant exposure to tuberculosis, place a tuberculin skin test. If influenza is a consideration, acquire a nasal wash. Liver function studies should be included if Q fever is considered. A coagulation profile is warranted if lassa or hantavirus are considerations. Urinary antigens can be sent if Legionnaires disease is a consideration.
| Table 9. Post-Travel Pneumonia Laboratory Testing |
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Life Threats or Disease with Public Health Implications
The history, physical examination, and laboratory investigations for patients seeking attention for post-travel care are geared to detect the medical conditions that have implications for the health of the individual and society.
For any pediatric patient who appears to have severe sepsis or impending septic shock, treatment is multi-faceted and may include supplemental oxygen, fluids and inotropes to support circulation, ventilatory support, and broad-spectrum antibiotics. Despite maximum therapeutics, case fatality ratios are > 30-40% for meningococcemia, rickettsial infections, and malaria. A more rapid administration of antibiotics has not been shown to improve outcome with meningococcal sepsis.37 Earlier recognition and antimicrobial treatment for Rocky Mountain spotted fever and malaria have been shown to be of benefit.14,38 There are no specific antiviral treatments for lassa, dengue, hantavirus, or fulminant viral hepatitis. These diseases are disproportionately morbid infections for which physicians can only provide supportive care. There are some data to suggest that the probability for surviving hantavirus infection is increased with early ED recognition and hospitalization.39
Great attention must be given when a pediatric patient is suspected to have a serious infection that is easily disseminated. Institute barrier techniques to decrease exposure of health care personnel. Medical personnel should wear gloves, gowns, and masks during patient care activities and procedures. Isolate the patient. Contact an infectious disease consultant who can determine if additional airborne, droplet, or contact transmission precautions need to be taken.
For specific infectious diseases, prophylactic therapy is recommended to prevent secondary spread among close contacts. For example, the emergency physician can initiate antibiotic or antiviral prophylaxis for close contacts of invasive meningococcal disease, pertussis, plague and influenza. The emergency physician can additionally initiate or schedule preventative vaccinations for family members at risk. Examples include hepatitis and rabies.
Reporting of infectious disease with high risk of nosocomial transmission is mandated by each state. However, for suspected, unconfirmed cases with high morbidity and mortality, it is prudent to contact either the state authorities or the Centers for Disease Control and Prevention. They may provide advice about the diagnosis of unusual infectious diseases and immediate management techniques. The ED should serve as the front-line lead for disease surveillance and outbreak identification.33
Summary
The ill, returning pediatric patient brought to the ED will likely have complaints of diarrhea, respiratory tract illness or undifferentiated fever with or without a rash. In evaluating the returning pediatric traveler, a complete history is invaluable. The history should include traditional information and a detailed travel history. The physical examination may provide clues to specific pathogens. Several laboratory tests may be of utility to support an ED provisional diagnosis. Other laboratory tests may be of utility to the physician who sees the patient in followup. A majority of post-travel illnesses are unassociated with morbidity and mortality. Supportive care is the only requisite. Specific care is required in a few cases. Because the agents that cause illness in the traveler are legion, and not all are easily diagnosed at the first encounter, secure followup appointments for all patients evaluated in the emergency setting.
References
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