KF23. Most cases of acute traveler's diarrhea are caused by bacterial pathogens. Enterotoxigenic Escherichia coli (ETEC) is the most frequently identified causative agent worldwide (A-III).

KF24. In a significant percentage (30–50%) of cases of acute traveler's diarrhea, an etiological diagnosis cannot be made (A-III).

KF25. There are notable geographical variations with respect to the etiology of acute traveler's diarrhea, independent of the length of the trip (A-III).

KF26. For acute traveler's diarrhea, microbiological studies should be restricted to patients who present fever, dysentery, choleriform diarrhea, or who are dehydrated, immunosuppressed or have significant comorbidities (A-III).

KF27. The diagnostic method of choice for acute traveler's diarrhea is the conventional stool culture or cultures on selective media (depending on clinical suspicion) together with serial blood cultures if there is fever, although the diagnostic yield is low (A-III).

KF28. For any traveler with fever and acute diarrhea arriving from an endemic area, malaria should be ruled out with the appropriate methods (B-III).

KF29. Before traveling, the patient should be given information about the main self-treatment measures to be taken in case of diarrhea, and told to seek medical care in the presence of high fever, severe abdominal pain, bloody diarrhea, uncontrolled vomiting, or if self-treatment is ineffective (A-III).

KF30. For previously healthy adults, rehydration with conventional liquids, especially associated with loperamide, should be enough in cases of mild diarrhea (A-I).

KF31. Rehydration and restoration of electrolyte balance with antidiarrheal drugs and non-absorbable antibiotics (rifaximin) is indicated for moderate diarrhea, and for the old or immunocompromised with no previous history of invasive disease (A-III).

KF32. For severe diarrhea with obvious signs of dehydration, intravenous rehydration is recommended to restore the fluid and electrolyte balance (A-III).

KF33. The use of antidiarrheal agents is contraindicated in the presence of invasive disease (A-III).

KF34. The most useful drugs for the treatment of invasive diarrhea are fluoroquinolones or azithromycin, chiefly in single doses (A-I).

KF35. The pathogenesis of persistent traveler's diarrhea may fall into one of three major groups: persistent infection or co-infection; post-infectious syndromes (transient lactose intolerance, post-infectious irritable bowel syndrome, small intestinal bacterial overgrowth (SIBO) and tropical sprue); or an underlying gastrointestinal disease unmasked during or after the trip (A-III).

KF36. The most common infections in persistent traveler's diarrhea are due to protozoan pathogens, for which the diagnostic method of choice is the standard Comprehensive Parasitology profile, using specific stains based on clinical suspicion, and antigen detection methods and PCR, as available, for increased sensitivity (A-III).

KF37. Diagnosis of post-infectious irritable bowel syndrome is exclusively clinical (Rome criteria III–IV) and it is especially important to determine the state of digestive health before travel and to consider at an early stage whether there are clinical and analytical signs of alarm/organicity (A-III).

KF38. The incidence of tropical sprue may be underestimated. Its main differential diagnosis is with celiac disease. Upper endoscopy (EGD) to examine the jejunum and biopsy are frequently required to differentiate them (A-III).

KF39. Some authors recommend empirical therapy with nitroimidazoles if Giardia intestinalis is highly suspected, even if specific studies are negative (C-III).

KF40. The most common causes of fever of unknown origin in the returned traveler are, in order of frequency: malaria, arbovirus (e.g. dengue, Chikungunya, Zika) and bacterial infections (typhoid fever, rickettsial infections, Q fever and leptospirosis) (A-II).

KF41. Even though they are rare, serious diseases that are highly contagious, such as viral hemorrhagic fevers (e.g. Ebola, Lassa, Marburg, Rift Valley fever, Crimean-Congo hemorrhagic fever) should always be considered (C-III).

KF42. The traveler's provenance, period of incubation and specific risk exposures should provide guidance as to the etiology of the febrile process (A-II).

KF43. Travelers who present with fever of unknown origin after visiting a tropical or sub-tropical area should seek immediate medical attention (A-II).

KF44. If there is any possibility of viral hemorrhagic fever (VHF), this should be investigated using appropriate biosafety measures and techniques that require the least handling possible (rapid tests or PCR) (A-II).

KF45. A significant proportion of fever episodes post-travel either do not lead to a specific diagnosis (A-II) or are due to cosmopolitan infections (A-II).

KF46. If there is no risk of VHF, malaria should be ruled out in the first instance using microscopy techniques and rapid diagnostic tests (A-II).

KF47. If the acute phase of an arbovirus is suspected (<10–15 days of clinical evolution), the patient should be tested for the presence of (NS1) antigens or viral RNA in blood and urine (A-II).

KF48. If arbovirus in later stages is suspected (>15 days of clinical evolution), the serologic response (principally IgM) should be studied and cases confirmed by neutralization tests (A-II).

KF49. The diagnosis of bacterial infection responsible for fever of unknown origin is based, in the acute phase, on isolating the bacterial organism or using molecular biology techniques, and in later phases, on serologic studies of paired serum samples (A-II).

KF50. Treatment (etiological or symptomatic) should be based on identifying the causative agent (A-II).

KF51. If there is a high probability of malaria and a diagnosis cannot be made, or will be delayed for more than 3h with no alternative diagnosis, administration of empirical antimalarial therapy is recommended (A-II).

KF52. Patients with a likely diagnosis of severe acute schistosomiasis or neuroschistosomiasis are treated with corticosteroids in combination with praziquantel (B-II).

KF53. In complicated or severe cases of malaria, use of ceftriaxone plus doxycycline is recommended while waiting for confirmation of diagnosis (C-III).

KF54. Various cosmopolitan infections, such as superficial mycoses (e.g. pityriasis versicolor, cutaneous candidiasis or dermatophytosis) and some ectoparasitic infections (such as scabies) are more frequent in travelers (A-II).

KF55. Classic bacterial infections constitute the leading cause of consultation for skin lesions and specifically, for those due to certain strains of methicillin-resistant S. aureus (MRSA) that produce Panton-Valentine leukocidin (PVL) (A-II).

KF56. The primary morphology of the lesion (e.g. papules, pustules, nodules, ulcers, blisters), configuration (e.g. linear) and distribution (exposed versus covered areas, specific parts of the body) are helpful for diagnosis (A-II).

KF57. In most cases, diagnosis is clinical, and dermoscopy is useful for some entities (scabies, cutaneous larvae migrans, furuncular myiasis and tungiasis) (B-III).

KF58. A helminth infection should be suspected if eosinophilia is associated with the skin lesions (A-II).

KF59. In an imported dermatosis that develops slowly, cutaneous leishmaniasis, mycobacterial infection or a subcutaneous mycosis should be suspected. Histological examination and identification of the causative agent with molecular biology techniques or mass spectrometry is essential (A-II).

KF60. For many imported dermatoses, treatment is symptomatic with oral antihistamines (diphenhydramine, hydroxyzine, or loratadine), topical antipruritic therapy (calamine lotion) and topical corticosteroids (low potency for the genitals, medium potency for the trunk or extremities) (A-II).

KF61. The treatment of choice for the main imported dermatoses that are linear in pattern (cutaneous larva migrans (CTM), cutaneous larva currens and gnathostomiasis) is ivermectin, with albendazole an alternative option (A-I).

KF62. Surgical removal (associated with antibacterial tetanus chemoprophylaxis where appropriate) is the treatment of choice for furuncular myiasis, tungiasis, and D. repens infections (A-II).

KF63. The most common causes of respiratory infection in the local environment are also the most common among travelers, with exotic imported infections being much less frequent (A-II).

KF64. In general, viral and bacterial infections are more frequent than those caused by fungi and parasites (B-II).

KF65. Most respiratory infections in travelers are mild, affect the upper respiratory tract and are caused by viruses (A-II).

KF66. The most serious respiratory infection in travelers is pneumonia, and the most common causes of it in the traveler are similar to those in the autochthonous population, although with a greater incidence of infections due to S. aureus and Legionella spp. (A-II).

KF67. During short trips, the risk of tuberculosis is low and depends on the incidence of the disease in the countries visited (B-III).

KF68. The main causes of respiratory conditions associated with eosinophilia are acute schistosomiasis, Löffler's syndrome and paragonimiasis (B-III).

KF69. Travelers may also have non-infectious problems that have respiratory manifestations such as pulmonary embolism and mefloquine toxicity (B-III).

KF70. Most respiratory infections during and after travel do not require diagnostic confirmation because they are mild, self-limited upper respiratory tract infections (A-II).

KF71. The diagnostic methods for pneumonia are no different from those used on autochthonous patients (B-II).

KF72. In patients with pneumonia, the decision as to whether a patient with pneumonia should be admitted to hospital or the ICU should be based on severity scales used in the autochthonous population (A-II).

KF73. Procalcitonin levels can guide the clinical judgment of the attending physician in prescribing antibiotics for respiratory infections (B-II).

KF74. If tuberculosis is suspected, or any other infection transmitted via respiratory secretions (such as the MERS-CoV coronavirus), respiratory isolation and droplet precautions are recommended (A-I).

KF75. Most respiratory infections during and post-travel do not require specific treatment because they are mild and self-limiting. Treatment may be given for the symptoms (B-III).

KF76. For pneumonia in travelers, antibiotic therapy is initially empiric and should include drugs effective against the most common community-acquired pathogens, including Legionella spp. (B-II).

KF77. In travelers with influenza and severity criteria or risk factors, treatment with oseltamivir or zanamivir is recommended (B-II).

KF78. If the traveler with tuberculosis has come from a country with a high incidence of antimicrobial resistance, it would be reasonable to evaluate treatment with at least 4 drugs and rapid DNA-based tests to detect mutations associated with resistance (B-III).

KD79. The causes of imported eosinophilia vary a good deal and depend on the characteristics of the patient, particularly whether the person is a traveler or an immigrant, and on the geographical destination, itinerary and length of exposure (B-II).

KD80. When a patient presents with imported eosinophilia of non-filarial etiology, it is important to rule out infection due to parasites, principally helminths (A-II).

KD81. In patients with imported eosinophilia, the cause is identified as a parasite in 60–75% of cases (B-II).

KD82. The three most frequently found parasitic infections are strongyloidiasis, schistosomiasis and soil-transmitted helminth infections, as well as filariasis in the case of Equatorial Guinea (B-II).

KD83. All returning travelers with eosinophilia should request a stool examination to search for parasites using a concentration method and Strongyloides stercoralis serology (B-II).

KD84. Travelers returning from Africa should request tests for diagnosing schistosomiasis (examination of the urine sediment and feces), and Schistosoma spp. serology (B-II).

KD85. In cases where a diagnosis cannot be made with direct techniques, serological methods are a useful diagnostic tool, although their possible drawbacks should not be forgotten (B-III).

KD86. When the cause cannot be identified, the empiric treatment for imported eosinophilia should be a combination of oral ivermectin plus albendazole. Praziquantel should be added for cases with possible epidemiological exposure to schistosomiasis (B-III).

KD87. Before starting empiric ivermectin therapy, the possibility of Loa loa infection should first be ruled out (A-II).

KD88. When empiric anthelmintic treatment is administered, the patient should receive clinical follow-up with monitoring of peripheral blood eosinophil counts, since some parasites, like Trichuris spp. and Schistosoma spp., have developed resistance leading to anthelmintic treatment failure (A-II).

KF89. The most frequent causes of neurological disease in travelers are malaria, viral infections and bacterial meningitis (A-II).

KF90. Generally speaking, the main clinical manifestations affect the brain and/or meninges, and more rarely, the spinal cord and peripheral nervous system (B-III).

KF91. The main manifestation in the peripheral nervous system is Guillain-Barré syndrome, which is associated with infection due to Campylobacter jejuni, dengue and, more recently, the Zika virus (B-II).

KF92. Any international traveler who returns with fever, severe headaches, sensitivity to light and/or a stiff neck should be evaluated urgently to rule out the presence of meningitis or encephalitis (A-III).

KF93. The cerebrospinal fluid (CSF) analysis can adopt four different patterns: normal, raised neutrophils, raised lymphocytes, raised eosinophils, which is useful for differential diagnosis (A-II).

KF94. Direct ophthalmoscopy is recommended for all patients with a diagnosis or suspicion of cerebral malaria, given its high prognostic and diagnostic value for malarial retinopathy (A-II).

KF95. The possibility of infection with extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae should always be considered in travelers with urinary tract infections, principally those acquired in South and Southeast Asia (A-III).

KF96. In the presence of non-specific complaints and/or hematuria, urinary schistosomiasis (S. haematobium) should be considered in travelers returning from traditionally endemic areas (and other more recently reported ones, such as Corsica) (A-II).