Leprosy in blood donors.

Area of Science:

• Infectious Diseases
• Immunology
• Public Health

Background:

• Leprosy remains a public health concern, particularly in endemic regions.
• Early detection is crucial for preventing transmission and disability.
• Blood donors are a unique population for screening potential asymptomatic cases.

Purpose of the Study:

• To determine the prevalence of anti-phenolic glycolipid-I (PGL-I) IgM antibodies in temporarily unfit blood donors in northern Brazil.
• To evaluate the diagnostic yield of anti-PGL-I IgM screening for identifying new leprosy cases.
• To assess the utility of clinical evaluation and molecular methods in confirming leprosy diagnoses.

Main Methods:

• Blood samples from temporarily unfit donors were tested for anti-PGL-I IgM using ELISA with a high optical density cutoff (OD ≥0.750).
• Donors with high antibody titers were invited for clinical examination, slit skin smear (SSS) bacilloscopy, and quantitative PCR (qPCR) for Mycobacterium leprae.
• qPCR targeted the repetitive element (RLEP) sequence in dermal scrapes and peripheral blood.

Main Results:

• Of 500 donors tested, 20 (4.0%) showed high anti-PGL-I IgM titers.
• Eight donors attended clinical evaluation, leading to the diagnosis of 5 new leprosy cases (62.5% of evaluated).
• Mycobacterium leprae was detected in 25-42.9% of cases via SSS bacilloscopy and qPCR.

Conclusions:

• A high anti-PGL-I IgM cutoff identified a significant number of undiagnosed leprosy cases among temporarily unfit blood donors.
• Targeted leprosy screening in this donor group is supported by these findings.
• Individuals with clinical signs of leprosy require prompt treatment and reassessment of blood donation eligibility.