From the Guidelines
The initial diagnostic approach for a patient with intermittent fevers, elevated WBC count, and recent travel to South America should include a comprehensive travel history, physical examination, and targeted laboratory testing, with a focus on ruling out malaria and dengue, as these are the most common diagnoses amongst febrile travelers and migrants, as indicated by the systematic review and meta-analysis 1. The patient's recent travel to South America increases the risk of contracting diseases such as malaria, dengue, and other parasitic infections.
- A detailed history focusing on specific locations visited, activities undertaken, insect exposures, food and water consumption, and timing of symptom onset relative to travel is crucial in identifying potential exposures.
- Physical examination should include evaluation for splenomegaly, which has a high likelihood ratio for a positive diagnosis of malaria, as well as other signs such as skin rash, which may indicate dengue or rickettsioses 1.
- Laboratory testing should include:
- Complete blood count with differential to evaluate for thrombocytopenia, leucopenia, and eosinophilia, which are significant predictors of malaria, dengue, and schistosomiasis, respectively.
- Comprehensive metabolic panel to assess for hyperbilirubinemia, which is a predictor of malaria.
- Blood cultures to rule out bacterial infections.
- Thick and thin blood smears to evaluate for malaria and other blood parasites.
- Dengue and chikungunya serology, leptospirosis antibodies, and stool examination for ova and parasites to rule out other endemic diseases.
- Consider typhoid testing and tuberculosis screening depending on exposure risk, as these diseases are also prevalent in South America.
- Chest X-ray and abdominal ultrasound may help identify potential sources of infection, such as pneumonia or abdominal abscesses. While awaiting results, supportive care with hydration and antipyretics is appropriate, but avoid NSAIDs if dengue is suspected due to bleeding risk, as indicated by the study 1. Empiric antimicrobial therapy may be necessary based on clinical presentation and suspected pathogens. This approach is essential because South America has endemic diseases not commonly seen in other regions, which require specific diagnostic methods for identification and appropriate treatment.
From the Research
Initial Diagnostic Approach
The initial diagnostic approach for a patient with intermittent fevers, elevated White Blood Cell (WBC) count, and recent travel to South America involves considering various tests to determine the underlying cause of the symptoms.
- The patient's recent travel to South America increases the risk of malaria, which is a significant concern in this region 2, 3.
- Intermittent fevers and elevated WBC counts are common symptoms of malaria, making it essential to include malaria testing in the diagnostic approach 4, 5.
- Rapid Diagnostic Tests (RDTs) are a valuable tool for diagnosing malaria, particularly in outpatient settings, and have been shown to have high sensitivity and negative predictive value for Plasmodium falciparum 2, 5.
- However, RDTs may not detect all cases of malaria, especially those with low parasitaemia, and therefore, additional tests such as thick-film microscopy, polymerase chain reaction (PCR), or quantitative PCR may be necessary to confirm the diagnosis 4, 6.
Diagnostic Tests
The following diagnostic tests may be considered:
- Rapid Diagnostic Test (RDT) for malaria 2, 5
- Thick-film microscopy for malaria 3, 4
- Polymerase chain reaction (PCR) for malaria 4, 6
- Quantitative PCR for malaria 6
- Blood smears to rule out other infections 2, 3
Considerations
When selecting a diagnostic test, it is essential to consider the patient's clinical presentation, travel history, and the performance characteristics of the test, including sensitivity, specificity, and negative predictive value 2, 3, 4, 5, 6.