Fw: Ref.: (LML) "Ping pong reinfection" of LL HD patients

 

Leprosy Mailing List – August 26,  2021

 

Ref.:  (LML) "Ping pong reinfection" of LL HD patients

From:  Joel Almeida, London and Mumbai

 

Dear Pieter & colleagues,

 

LL (lepromatous) patients with genomically related anergy to HD bacilli are central to the epidemiology of HD (leprosy). In endemic areas, children who newly join the household of a patient under treatment experience an elevated risk of developing signs of HD, if another individual with particular characteristics is present in that same household. What are the characteristics of that other individual? They were previously treated for HD.

 

What is going on? Take an illustration.

 

We can elaborate on this with an example. An LL patient with genomically related anergy to HD bacilli starts and completes treatment in an endemic area. Let's call them person A. Meanwhile, one or more family members with anergy have been incubating LL HD. Let's call them person B. Person A, after the withdrawal of anti-microbials, remains highly susceptible to reinfection. Person B sheds astronomical numbers of bacilli in nasal discharges and has enormous numbers of bacilli in nerves, bloodstream, skin and other organs. However, Person B shows no patches and few (if any) physical signs. Smear microscopy is omitted, delaying diagnosis.

Person B reinfects Person A. Meanwhile, Person B develops visible signs of HD and is started on a fixed duration of anti-microbials. Person A now starts to generate astronomical numbers of viable bacilli. However, this reinfection is not recognised promptly. Sequelae of previous infection mask the subtle physical signs of reinfection. Omission of smear microscopy does not help. 

 

Person A now sheds astronomical numbers of viable HD bacilli, unchecked. This increases the risk of infection in children who newly join the household of Person B. Person B is under treatment, and protected. But everyone else in their vicinity, including person A, is unprotected. 

 

Once Person A's reinfection becomes apparent, typically after 5 years or more, the roles of Persons A and B are reversed. In this way Persons A and B between them can keep "ping pong reinfection" going for years or even decades. These previously treated but since neglected LL patients provide a key source of concentrated viable bacilli in that area. Anti-microbial neglect of LL patients after 12 months of MDT imposes on them the role of super-spreaders. These LL patients also experience a huge increase in the risk of painful, swollen nerves of ENL neuritis. We could spare them from this easily avoidable suffering.

 

Wherever prolonged anti-microbial protection was ensured for LL patients, the incidence rate of MB or LL HD declined fairly rapidly (16% to 20% per year). This happened even when incomes in those places were conspicuously low (Karigiri, Uele, Shandong). The addition of repeated mass multi-drug administration in hyperendemic hot spots can turbo-charge such success. With annual mass multi-drug administration added to skin camps and prolonged MDT for LL patients, an 84% decline within only 2 years was demonstrated in the incidence rate of HD. The consistent use of multi-drugs for treatment or prophylaxis, instead of a single drug, delays the selection of drug resistant mutant bacilli. This helps to maintain the efficacy of MDT.

 

"Ping pong" reinfection between LL patients can be ended. We could ensure prolonged anti-microbial protection of LL patients, following 12 months of MDT. This will rapidly reduce transmission as well as the risk of excruciatingly painful ENL neuritis among previously treated LL patients. We will succeed, because we are a noble-minded community dedicated to preventing or alleviating human suffering, and we are open to learning from the dramatic front-line successes created by great colleagues.

 

Joel Almeida

 

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

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

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

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