COMMENTARY

Evaluation of the Returning Traveler With Fever

Keren Z. Landman, MD

Disclosures

October 25, 2016

In This Article

Other Infections to Consider

Malaria

Malaria is the infection to assess for first. "Depending on what part of the world the patient is coming from, it may be a low-probability event," says Paul Arguin, MD, chief of the Domestic Response Unit in CDC's Malaria Branch. "But being that it has the potential for severe illness, fatality, and disability, it can be diagnosed quickly, and rapid treatment makes such a difference; it should always be right at the top of the list of things that get evaluated."

In addition, although individual patients' disease patterns can inform the diagnostic process, the clinical features of many travel-related illnesses overlap substantially, and looking for signs and symptoms to rule out high-morbidity diseases can be a trap. "I would never try to rely 100% on clinical features" to determine which testing should be done, says Dr Arguin. Just because a traveler recently returned from the tropics and has respiratory symptoms along with fever and chills, for example, "that shouldn't make you think, 'That's not malaria,'" he says.

Some malaria species can cause symptoms months after return from travel. Malaria is still endemic throughout Latin America, including Brazil, and on the island of Hispaniola (composed of Haiti and the Dominican Republic) in the Caribbean. (The CDC maintains a list of malaria information by country and a Malaria Map, which provide information about malaria species and risk.)

Any patient with a fever who has traveled to an endemic area should have at least one set of thick and thin malaria smears, which should be read emergently by a pathologist. Three sets of negative smears, separated by 12-24 hours, effectively rules out malaria. The CDC's malaria hotline (770-488-7788 or 855-856-4713 during business hours, or 770-488-7100 for emergency consultation after hours) can be reached around the clock to assist healthcare providers with the diagnosis or management of malaria, and often can provide assistance with reading smears if a pathologist is not immediately available.

Dengue Virus

A more common cause of fever in travelers to Latin America and the Caribbean is the dengue virus. Dengue should be suspected when a patient presents with high fever and other symptoms such as headache, retro-orbital pain, muscle and joint pains, nausea and vomiting, or lymphadenopathy. The infection is not curable with antiviral drugs. Up to 5% of all dengue patients develop severe disease with hemorrhagic complications, including hypovolemic shock, and may require respiratory and circulatory support.

Identifying dengue enables the physician to advise avoiding aspirin and other nonsteroidal anti-inflammatory drugs (due to their anticoagulant properties), and to recommend close monitoring for symptoms suggestive of severe dengue.

Dengue is endemic throughout Latin America and the Caribbean, with occasional hyperendemicity of certain serotypes. Making the diagnosis is also important for epidemiologic purposes and for preventing unnecessary treatment for other disease entities.

Diagnosis has lately been complicated by the overlap of symptoms and epidemiology with those of Zika. Although reverse transcription polymerase chain reaction (RT-PCR) can differentiate between the two flaviviruses in the first 1-2 weeks of symptoms, making a definitive diagnosis later in the course of infection is more complex. Refer to CDC's Zika diagnostics Web page for up-to-date guidance.

Chikungunya

Chikungunya caused a large outbreak beginning in the Caribbean in late 2013, eventually resulting in over 1 million suspected cases reported by WHO in 2014.

Although the fever, flu-like symptoms, and prominent joint pain often associated with infection can be debilitating, mortality due to the disease is generally low. The diagnosis can be made by viral culture or nucleic acid amplification test during the first week after onset of symptoms, or by serology in the weeks thereafter.

Chikungunya's incubation period (2-7 days) and symptoms overlap substantially with those of dengue and Zika.[2] Testing performed at several state laboratories or CDC can usually differentiate between chikungunya and flavivirus infections, including dengue and Zika (by RT-PCR in the first 5 days of illness or by antiviral IgM serology thereafter).

Typhoid and Paratyphoid Fever

Typhoid and paratyphoid fever can also cause fevers and a variety of symptoms in visitors to the region, and is an important cause of morbidity and mortality, particularly in areas with poor sanitation. Although these infections are thought to have a lower burden in Latin America than in other regions,[3] they should be considered in returning travelers with persistent fevers. Because blood cultures have only 50% sensitivity for typhoid, the initial diagnosis may need to be made clinically. Multiple cultures increase culture sensitivity.

Influenza

In febrile patients with respiratory symptoms, influenza virus may be a consideration. Flu season in the southern hemisphere peaks in July, a fact often forgotten by physicians practicing in the northern hemisphere, says Dr Davidson Hamer, a professor at the Boston University School of Public Health and School of Medicine, and a board member of the International Society of Travel Medicine (ISTM).

Nontravel Diagnoses in Travelers

It is also important to remember that travelers get community-acquired pneumonia, bacterial sepsis, meningitis, and other infections not related to travel. They may also have inflammatory, rheumatologic, and oncologic conditions that cause fever. These and other causes should be considered in parallel with travel-related diagnoses in the context of each patient's symptoms and medical history.

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