Fw: Ref.: (LML) Long-lasting adverse impact of chemoprophylaxis & what actually works

 

Leprosy Mailing List –  September 8,  2026

 

Ref.:  (LML) Long-lasting adverse impact of chemoprophylaxis & what actually works

From: Laila de Laguiche, Curitiba, Brazil

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Dear Pieter and colleagues,

This discussion brings us, in my view, to a fundamental question: what level of evidence should be required before changing public health policy in leprosy?

We clearly need better prevention, earlier diagnosis and better treatment. However, regarding transmission and prophylaxis, important questions remain unanswered. 

We still need to distinguish exposure, healthy carriage, subclinical infection and disease. 

Anti-PGL-1 positivity may reflect exposure and does not, by itself, indicate disease. 

Likewise, a positive nasal PCR does not necessarily mean viable bacilli, and viability does not necessarily mean infectiousness. 

We still do not know which asymptomatic carriers actually contribute to transmission, or the minimum infectious dose of M. leprae.

This uncertainty has direct implications for PEP. Before treating asymptomatic individuals, we should know better whom we are treating and why: exposure, presumed latent infection, or a demonstrated risk of transmission or progression to disease.

These uncertainties matter when deciding whom to treat, when to treat and with what regimen.

In 2017, in Brazil, I questioned shortening MDT based on the evidence then available for U-MDT. My concern was not resistance to innovation, but the level of evidence required before introducing a major change in public health practice. I believe the same principle remains valid today.

Leprosy control is implemented largely through public health policies. Whether we discuss PEP, early diagnosis, shorter or prolonged MDT, daily rifampicin or new therapeutic regimens, changes in policy should be supported by robust, reproducible evidence of efficacy and safety.

We need innovation. Hopefully, new evidence will lead us towards better prevention, earlier diagnosis and shorter, safer and effective treatment with fewer adverse effects. 

But innovation and scientific rigor must move together.

Best regards,

Laila de Laguiche

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LML - S Deepak, B Naafs, S Noto and P Schreuder

LML blog link: http://leprosymailinglist.blogspot.it/

Contact: Dr Pieter Schreuder << edit...@gmail.com

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