High seropositivity against NDO-LID in a group of household contacts of leprosy patients. Are we close to leprosy elimination in Colombia?

Introduction: Leprosy is a chronic infectious disease caused by two mycobacteria (Mycobacterium leprae and Mycobacterium lepromatosis). The household contacts (HHC) of leprosy index cases are at higher risk of being infected with these mycobacteria. Therefore, serological testing in HHC would be an effective strategy to eliminate leprosy in Colombia.

Objective: To determine the seroprevalence and factors associated with the infection by M. leprae in HHC.

Methods: An observational study was conducted in 428 HHC located in the Colombian Caribbean, Andean, Pacific, and Amazonian regions. We evaluated the seropositivity and titrations of IgM, IgG, and protein A against NDO-LID.

Results: The evaluated HHC showed high seropositivity, precisely 36.9% anti-NDO-LID IgM, 28.3% anti-NDO-LID IgG, and 47.7% protein A. Furthermore, Protein A showed a greater capacity to detect infected individuals than other anti-NDO-LID conjugates (p < 0.0001). This study did not show differences in the seropositivity according to sex or age of the HHC (p > 0.05). Higher seropositivity for IgM was evidenced mainly in HHC located in the Colombian Pacific region (p 0.001). This research did not show differences in the seropositivity for these serological tests between HHC of PB or MB leprosy patients (p > 0.05).

Conclusion: Leprosy transmission is still active between Colombian HHC. Consequently, controlling leprosy transmission in this population is fundamental to eradicating this disease.