Important factors to consider would include the destination and the nature of the trip that was taken (business, leisure, and medical) as well as a description of accommodations, information about pretravel vaccinations or chemoprophylaxis during travel, a sexual history, and a list of exposures and risk factors.
Knowledge of water and insect exposures, as well as what kind of human (sexual, medical) contacts occurred, can be used to help determine the degree of risk that exists for each patient.
Seasonality and trip duration are important factors as well.
Tables 21-1 and 21-2 may provide helpful clues to help determine an etiology.
The incubation period of the illness often can help the physician formulate a differential diagnosis.
Infection is the most common cause of fever in the returned traveler, but other causes such as medications, thromboembolism, malignancy, and other noninfectious causes also need to be considered.
Fever patterns, although classically described, are seldom useful in the clinical setting.
See Table 21-3 for specific details.
Generally, a few illnesses account for the majority of diagnoses.
These would include malaria, dengue, typhoid, and viral hepatitis.
On the other hand, leptospirosis, amoebic liver abscess, viral meningitis, and relapsing fever are rare causes of febrile illness in the returning travelers.
Immunization history and compliance with antimalarial chemoprophylaxis are helpful clues to the etiology of fever.
Even though these measures clearly decrease the risk of acquiring malaria, no antimalarial chemoprophylactic regimen is completely protective.
Poor adherence with antimalarial drug regimens is well documented in travelers who contract malaria.
Malaria was the most common cause of hospital admissions in ill travelers in several studies from Europe, Australia, and Israel.
The most common illness that requires immediate treatment is Plasmodium falciparum malaria.
Table 21-1 Risk Factors for Infection after Travel
Exposure
Potential Diseases
Undercooked food
Cholera, salmonellosis, typhoid fever, Escherichia coli
Milk
Brucella, Salmonella, tuberculosis
Water exposure
Leptospirosis, schistosomiasis, dracontiasis
Infected animals
Brucellosis, plague, Q fever, rabies, tularemia, monkey pox, leptospirosis
Mosquitoes
Dengue fever, malaria, encephalitis
Ticks
Rickettsial diseases, tularemia, Colorado tick fever, relapsing fever, Babesia, typhus, Lyme, Crimean hemorrhagic fever
Reduviids
American trypanosomiasis
Tsetse flies
African trypanosomiasis
Sexual contacts
Chancroid, gonorrhea, hepatitis B, herpes, and HIV
Sick contacts
Meningococcal disease, tuberculosis, VHFs, severe acute respiratory syndrome (SARS)
Transfusion
Hepatitis, HIV, malaria, Chagas
This should be urgently investigated with thick and thin blood smears. One of the most useful investigation for fever in returning travelers is a malaria film, which was positive in 45% of cases in which it was performed.
The second largest group was assumed to have a nonspecific viral infection (25%).
Cosmopolitan infections (urinary tract infection, community-acquired pneumonia, streptococcal sore throat, etc.) accounted for 9%.
Table 21-2 Incubation Periods
Less than 21 Days
More than 21 Days
Meningococcemia
Acute HIV infection
Nontyphoidal salmonellosis
Schistosomiasis
Plague
Epstein-Barr virus
Typhoid fever
Filariasis
Typhus
Secondary syphilis
VHFs
Amebic liver abscess
Yellow fever
Borreliosis (relapsing fever)
Campylobacter
Brucellosis
Toxigenic E. coli
Leishmaniasis
Influenza
Malaria
Rickettsial diseases
Rabies
Shigella
Tuberculosis
Measles
Viral hepatitis (A, B, C, D, E)
CMV
West African trypanosomiasis
East African trypanosomiasis
Dengue fever
Japanese encephalitis
Leptospirosis
Malaria
Table 21-3 Fever Patterns
Fever Patterns
Illness
Comments
Tertian
P. vivax
Fever spike every other day
Quartan
P. malariae
Spike every 3rd day
Saddleback
Dengue, yellow fever, and Colorado tick fever
Biphasic pattern. Febrile period between spikes
Relapsing
Borealis spp.
A period of days or weeks between spikes
Undulant
Brucellosis, visceral leishmaniasis
Moving like waves
Bradycardia
Typhoid and yellow fever
Relative to the temperature
Breakbone
Dengue
Severe myalgias
Coincidental infections (schistosomiasis, filariasis, and intestinal helminths) were found in 16%.
Serology was positive for HIV infection in 3%.
Respiratory infections including influenza, diarrheal diseases, and urinary tract infections are, as a group, among the most common causes of fever in travelers.
The presence of a rash often will alert the physician to a specific diagnosis (Table 21-4).
A biopsy with pathologic analysis and culture can be very helpful.
Splenomegaly and lymphadenopathy are often present as well (Table 21-5).
Table 21-4 Differential Diagnosis of Skin Lesions Associated with Travel
Maculopapular
Petechiae
Eschar
Chancre
Ulcers
Papular
Dengue
Dengue
Anthrax
Syphilis
Leishmaniasis
Syphilis
Rubella
Leptospirosis
Mycobacteria
Insect bites
Epstein-Barr virus (EBV)
African
Insect bites
Tungiasis
Rickettsia
Rickettsia
Rickettsia
Trypanosomiasis
STDs
Myiasis
Meningococcemia
Meningococcemia
Scrub typhus
Sporotrichosis
Onchocerciasis
Rose spots in typhoid fever
Measles
Table 21-5 Diseases Associated with Lymphadenopathy and Splenomegaly
Lymphadenopathy Localized
Generalized
Splenomegaly Bacterial
Nonbacterial
Plague, tularemia
African trypanosomiasis
American trypanosomiasis, filariasis, toxoplasmosis
Tuberculosis
Brucellosis, leptospirosis, melioidosis
Dengue fever, Lassa fever, measles
Visceral leishmaniasis
HIV infection, secondary syphilis
Enteric fever, brucella, endocarditis, leptospirosis, typhus
EBV, CMV, HIV, malaria, visceral Leishmaniasis, trypanosomiasis, schistosomiasis
The most common diseases in the tropics that present with fever and eosinophilia are acute schistosomiasis (Katayama fever) and ascariasis (Table 21-6).
Diseases that may be associated with jaundice are noted in Table 21-7.
Urgent evaluation of a potential P. falciparum malaria infection is required because it carries a high fatality rate of more than 20%. Attention should be given to the type of and compliance with any previously prescribed antimalarial medication.
Perhaps out of a false sense of security, a greater prevalence of malaria is seen in residents of developing countries who have returned home to visit friends and relatives.
Table 21-6 Degree of Eosinophilia
None to Rare
Minimal to Moderate
Moderate to Significant
Protozoa (Isospora, Toxoplasma rarely)
Tapeworms
Filariasis
Ascariasis
Clonorchiasis
Enterobiasis
Trichuriasis
Hydatid disease
Cysticercosis
Trichinosis
Loaiasis
Strongyloidiasis
Ascariasis
Hookworm
Paragonimiasis
Onchocerciasis
Fascioliasis
Schistosomiasis
Paragonimiasis
Fasciolopsiasis
Toxocariasis
Angiostrongylus
Gnathostomiasis
Table 21-7 Causes of Jaundice
Bacterial
Nonbacterial
Leptospirosis
Severe malaria
Typhus
Fascioliasis
Typhoid
Cytomegalovirus
Viral hepatitis
Yellow fever
Regardless of whether antimalarial medication was taken, patients should have thick and thin smears (at least three over 48 hours) ordered for malaria.
Symptoms of P. falciparum infection are usually apparent within 2 months of returning, but those caused by other species might take longer to present (several months). Some patients, such as immigrants and visitors from endemic areas and those taking chemoprophylaxis, may have delayed onset or atypical presentation.
Almost all patients will report fever but not necessarily with classic fever pattern as noted in Table 21-3.
They may also complain of malaise, headache, myalgias, and gastrointestinal symptoms. Jaundice and hepatosplenomegaly also may be seen as well.
Rash and lymphadenopathy, however, are uncommon and should suggest another diagnosis. The World Health Organization (WHO) defines severe malaria as a parasitemic person (>5%) with one or more of the following: prostration, impaired consciousness, respiratory distress or pulmonary edema, seizures, circulatory collapse, abnormal bleeding, jaundice, hemoglobinuria, and anemia.
Several complications of severe malaria can occur and include severe anemia, acute renal failure, respiratory failure, intravascular hemolysis, and cerebral malaria.
Hematologic abnormalities are common, and liver function test results are often abnormal.
An elevated bilirubin level in the face of a high lactate dehydrogenase level suggests hemolysis. Hypoglycemia and hyponatremia may be present as well.
See Table 21-8 for details clinical manifestations of malaria.
The thick blood film provides enhanced sensitivity of the blood film technique and is much better than the thin film for detection of low levels of parasitemia. As shown in Table 21-9, a thin smear is more useful for species identification than a thick smear.
A recognized way of estimating the number of parasites present in 1 µL of blood is to use a standard value for the white blood cell (WBC) count (8,000 WBC/µL).
Counting the number of parasites present until 200 WBCs have been seen and then multiplying the parasites counted by 40 will give the parasite count per microliter of blood.
The sensitivity for the examination of the thick blood film procedure is about 50 parasites/µL of blood, which is equivalent to 0.001% of red blood cells (RBC) infected.
The identification of the parasite to the species level is much easier and provides greater specificity.Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
