Leprosy Mailing List – February 6, 2018
Ref.: (LML) Reliability of global leprosy statistics
From: Joel Almeida, London and Mumbai
Thank you for the mail by Claudio Salgado "Reliability of Global Leprosy Statistics" of February 1, 2018.
A sample survey in Brazil (Amazon) found that 4% (95% c.i. +/-1%) of school children with a mean age of 13.3 years had clinical signs of leprosy (1). Almost 50% of school children had seropositivity for antibodies to the M.leprae-specific phenolic glycolipid-1.
Such sample surveys performed by skilled clinicians seem more reliable than the numbers usually reported to WHO. Those serious about controlling leprosy and its disfiguring consequences might usefully use such sample surveys in their own localities. This can help generate political and public support with a consequent boost in financing.
The picture that typically emerges in endemic areas is of a population swimming in a sea of M. leprae.
Even door-to-door case detection campaigns by inexperienced personnel are likely to miss signs of leprosy while mistaking other signs for leprosy. Sample surveys performed by skilled clinicians are more reliable.
In the past, skilled clinicians in India have found that the vast majority of people with clinical signs were missed by inexperienced workers. The true incidence rate of clinical signs of leprosy may well be between 4 and 9 times that found by case detection campaigns using inexperienced workers.
The number of cases on the register is meaningless. It can be reduced to zero within one minute by a simple expedient: remove all cases from the register after the first dose of MDT. Then the point prevalence of registered cases will immediately become zero. In finance, there is a term for such practices: cooking the books.
Unfortunately, some still rely on prevalence of cases on the register to declare a 90% or 99% reduction in leprosy. This is epidemiological nonsense in the context of shortened durations of MDT. Worse, it has been damaging on 3 fronts:
1) Less money for leprosy work
2) Less bright young talent coming into leprosy work
3) Less attention to protecting the nerves of people during and after MDT, with an increasing burden of permanent disfigurement.
Leprosy continues to infect children, and in India it has doubled the number of cases with visible deformity at diagnosis, since 2005-6..
In TB, the 1980s saw a premature declaration of victory with over-optimistic promises. In the 1990s I had the privilege to be part of Dr. Arata Kochi's team at WHO HQ. We put TB back on the global agenda, with an increase in financing from under 100 million USD per year to several billion USD/year now.
The first step was to decisively and firmly correct the mistaken notion that TB was declining, and that victory was imminent. The second was to draw attention to the impact of TB on human lives.
In leprosy, we are at the first mile of a marathon. We can attempt this journey blindfolded and spouting dubious claims, or we can do this with our eyes open and testing our claims with sample surveys carried out by skilled and experienced clinicians.
Our Brazilian colleagues have set a good example, as have Indian colleagues who carry out sample surveys. May their example spread.
1. Josafá Gonçalves Barreto; Layana de Souza Guimarães; Marco Andrey Cipriani Frade; Patricia Sammarco Rosa; Claudio Guedes Salgado. High rates of undiagnosed leprosy and subclinical infection amongst school children in the Amazon Region. Mem. Inst. Oswaldo Cruz vol.107 supl.1 Rio de Janeiro Dec. 2012
LML - S Deepak, B Naafs, S Noto and P Schreuder
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