Approach to a fever in the returned traveler: Clinical sciences

Fever, defined as a body temperature of at least 100.4 degrees Fahrenheit or 38 degrees Celsius, is a common symptom that can indicate the presence of infection. When talking about patients returning from recent travel, a fever might point to an illness endemic to the area they visited or emigrated from. There are many conditions to think about here, but assessing for the presence and type of rash can help you narrow down the differential.

When a patient presents with a fever after traveling, first perform an ABCDE assessment to determine if they are stable or unstable. If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, give IV fluids, and start continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry. If needed, provide supplemental oxygen, and consider starting antibiotics.

When it comes to stable patients, your next step is to obtain a focused history and physical examination. History typically reveals recent travel and fever with or without general malaise or headache. On exam, there is elevated temperature, but you might also find tachycardia and a rash. Assessing for the presence of rash is very important as it will help you narrow down potential diagnoses. If a rash is present, assess the rash morphology.

Let’s start with macular rashes, which appear as flat discolorations on the skin. First up is African sleeping sickness, also known as African trypanosomiasis. This illness is caused by the protozoan parasite Trypanosoma brucei and transmitted via Tsetse fly. Patients report a history of recent travel from sub-Saharan Africa and getting bitten by Tsetse flies. Soon after, they develop headaches, and in some cases, mood changes, drowsiness, and even weight loss.

As for the physical exam, it shows a painful chancre at the site of the fly bite and trypanid rash which is a transient rash on the trunk that appears as a predominantly macular rash with wheals. You might also note altered mental status. With these findings, consider African sleeping sickness and order microscopic analysis of the blood, cerebrospinal fluid, or chancre fluid. If the results show visible Trypanosoma brucei parasites, diagnose African sleeping sickness.

Moving on to dengue fever from the genus Flavivirus, which is transmitted by Aedes mosquitos. These patients have a history of recent travel from tropical or subtropical regions, mosquito bites, headaches, a significant amount of muscle and joint pain, and nausea. They might also report vomiting with abdominal pain.

Physical exam typically reveals a diffuse macular rash limited to the limbs and face. You might also note petechiae or purpura as the infection progresses. With these findings, consider dengue fever and order nucleic acid amplification testing, also known as NAAT, of serum, or serum antibody testing. If the results are positive for dengue viral RNA or anti-dengue immunoglobulin M, diagnose dengue fever.

Here’s a clinical pearl! Patients with dengue fever should avoid aspirin or other NSAIDs due to an increased risk of bleeding.

Okay, let’s move on to infections with maculopapular rash. This rash appears as a mix of flat discolorations and raised bumps. First up is Zika virus which is also from the Flavivirus genus. Patients report recent travel from tropical and subtropical regions with a history of mosquito bites. They may have joint pain, headache, vomiting, or itching.

Exam typically shows a maculopapular rash and possibly nonpurulent conjunctivitis. If this is the case, consider zika infection and order NAAT of the cerebrospinal fluid, serum, or urine. Alternatively, you can order serum antibody testing. If the NAAT is positive for Zika viral RNA or anti-zika immunoglobulin M is positive, you are dealing with Zika virus infection.

Time for a clinical pearl! Zika virus has been linked to microcephaly and other birth defects so pregnant patients should be cautioned against traveling to areas endemic for Zika virus.

Next up is chikungunya infection, an alphavirus from the Togaviridae family transmitted via an Aedes mosquito bite. Patients with this infection report travel from Africa or Southeast Asia, mosquito bites, headaches, nausea, and possible severe joint pain. Exam typically reveals a maculopapular rash on the trunk and extremities that may extend to the face, palms, and soles. With these findings, consider chikungunya infection and order virus-specific NAAT of serum or antibody testing. If the NAAT is positive for chikungunya RNA or anti-chikungunya immunoglobulin M is positive, diagnose Chikungunya virus.

Now, let’s discuss typhoid fever caused by strains of Salmonella enterica. In this case, patients report recent travel from developing countries, especially in South Asia, where they consumed unclean food or water that was likely contaminated with feces. They might also report gradually rising fever, malaise, headache, abdominal pain, vomiting, and diarrhea.