What is the approach to a recent immigrant presenting with pallor and fatigue, considering their potential exposure to infectious diseases in their country of origin or during travel?

Approach to Recent Immigrant with Pallor and Fatigue

In a recent immigrant presenting with pallor and fatigue, you must immediately prioritize excluding malaria, tuberculosis, and helminth infections, while simultaneously screening for latent infections endemic to their region of origin that can cause chronic anemia and systemic illness.

Immediate Life-Threatening Exclusions

Malaria Testing (Priority #1)

• Obtain three thick and thin blood films over 72 hours and/or rapid diagnostic test (RDT) immediately, as malaria accounts for 22.2% of all febrile illness in travelers from tropical regions and 67.7% of tropical diseases 1, 2
• Malaria must be excluded in any patient from endemic areas within the past year, even without fever, as chronic malaria can present with pallor and fatigue alone 2
• Treat empirically if high suspicion exists and the patient appears ill, even with initial negative tests 2

Tuberculosis Screening

• Perform tuberculin skin test (TST) or interferon-gamma release assay (IGRA) immediately, as tuberculosis was diagnosed in 112 cases among European travelers and represents 0.6% of travel-associated morbidity 3
• Latent tuberculosis infection was found in 60.6% of sub-Saharan African immigrants screened 4
• Obtain chest radiograph to evaluate for active disease if screening is positive 1

Essential Initial Laboratory Workup

Complete Blood Count with Differential

• Assess for eosinophilia (absolute count or percentage) and measure IgE levels, as these are better indicators of helminth infection than absolute eosinophilia, particularly for schistosomiasis and strongyloidiasis 4
• Evaluate hemoglobin, MCV, and peripheral smear to characterize the anemia 4
• Check platelet count, as thrombocytopenia suggests dengue, malaria, or other tropical infections 2

Helminth and Parasitic Screening

• Order stool examination for ova and parasites (three samples) testing specifically for Giardia, Cryptosporidium, Cyclospora, Entamoeba histolytica, and helminths, as 36.8% of sub-Saharan immigrants had intestinal parasites and 28.1% had helminths 4
• Obtain schistosomiasis serology if travel to endemic areas (sub-Saharan Africa, Middle East, South America) is reported 1
• Consider Strongyloides serology, as this can cause chronic infection with significant morbidity 4

Region-Specific Infectious Disease Screening

Sub-Saharan Africa Origin

• Test for visceral leishmaniasis with serology and consider bone marrow examination if hepatosplenomegaly is present, as this is endemic in the Horn of Africa 1
• Screen for HIV, as 1.2% of sub-Saharan immigrants tested positive 4
• Evaluate for chronic malaria and consider Plasmodium falciparum as the predominant species 3

Asia/Southeast Asia Origin

• Screen for enteric fever with blood cultures, as this accounts for 2.3% of febrile travelers and can present with chronic fatigue 1
• Consider hepatitis B and C testing, as 14.8% of sub-Saharan immigrants were hepatitis B surface antigen positive 4
• Evaluate for dengue if recent travel (within 2 weeks), though this typically presents acutely 2

Latin America Origin

• Consider Chagas disease screening with serology, particularly in immigrants from endemic regions, as this was identified as a risk in travelers from South America 3
• Screen for intestinal parasites including Strongyloides and hookworm 4

Additional Essential Testing

Hepatic and Renal Function

• Obtain liver function tests and renal function tests to evaluate for organ involvement from chronic infections 2
• Check for proteinuria and hematuria on urinalysis 2

Infectious Hepatitis Screening

• Test for anti-HAV IgM, HBsAg, anti-HCV, and anti-HEV IgM, as viral hepatitis accounts for 1.1% of febrile travelers 1

Brucellosis Consideration

• Obtain extended blood cultures and serology for brucellosis if there is history of contact with livestock or consumption of unpasteurized dairy products 1

Critical Pitfalls to Avoid

• Never assume simple nutritional anemia without excluding infectious causes first, as 72.8% of sub-Saharan immigrants had at least one pathogenic infectious disease 4
• Do not delay malaria testing even in the absence of fever, as chronic malaria can present with isolated pallor and fatigue 2
• Recognize that coinfections were present in 28.4% of screened immigrants, requiring comprehensive rather than focused testing 4
• Alert laboratory staff when suspecting infections that pose occupational hazards such as brucellosis or tuberculosis 2

Empiric Treatment Considerations

• Initiate isoniazid preventive therapy for latent tuberculosis in high-risk patients with positive screening tests and no evidence of active disease, particularly those under 35 years or with additional risk factors 5
• Consider empiric antimalarial therapy if clinical suspicion is high and patient appears ill while awaiting confirmatory testing 2
• Treat helminth infections promptly once identified, as these contribute significantly to anemia and can cause severe complications if untreated 4