Leprosy Mailing List – May 6, 2023
Ref.: (LML) Smear microscopy & transmission in India
From: Joel Almeida, Mumbai, India
Dear Pieter and colleagues,
Recent reports are that smear microscopy is increasingly being reintroduced in India. This will greatly improve the chances of diagnosing the new or reinfected "de novo" LL patients. They can show almost no physical signs, even while shedding tens of millions of viable bacilli per day.(1) It will allow anti-microbial protection for these patients who otherwise suffer a greatly increased risk of excruciatingly painful ENL neuritis (2). It will also protect the population who otherwise would face a relentless avalanche of viable bacilli.
There is no substitute for detection and anti-microbial protection of anergic "de novo" LL patients. Epidemiological stagnation has been observable during the past two decades, even in areas of the world where chemoprophylaxis with single dose rifampicin for household contacts was implemented diligently for several years (e.g., Sampang, Bima, Sumenep in Indonesia). (3) Without prolonged anti-microbial protection of LL patients in endemic areas the incidence rate of MB (multibacillary) HD is likely to remain roughly level for decades, or to decline very slowly. Chemoprophylaxis among contacts cannot cope with the relentless onslaught of astronomical numbers of viable bacilli from unprotected LL patients who are (re)infected but show no prominent signs. The resulting failure to achieve rapid reduction in transmission is wholly avoidable.
It may take a leap of imagination to move from the forward-contact-tracing habits of the past to a mindset of backward contact tracing. In forward contact tracing we have been allowing the avalanche of viable bacilli to continue. Then we look for the infected contacts. Backward contact tracing seeks to identify and treat the small minority of cases who are responsible for nearly all the viable bacilli shed in diseases such as HD. It is like plugging the hole in the dam. The dominant source of astronomical numbers of concentrated viable bacilli is shut down. This works powerfully.
Transmission by previously treated but reinfected LL patients is easily avoidable. Whenever LL patients in endemic areas receive prolonged anti-microbial protection, reinfection and transmission decline rapidly. This is illustrated by the well-documented declines in incidence rate of multibacillary HD in Uele, Karigiri and Weifang/Shandong. (4-6) These rapid declines occurred despite conspicuously low incomes in those places at the time. Further, prolonged anti-microbial protection of LL patients in endemic areas can avert as much as a 600% increase in the risk of painful ENL neuritis among these patients (2).
In endemic areas, prolonged multi-drug protection of LL patients and mass multi-drug administration (7) each have powerful epidemiological impact. This is because they shut down sources of infection, without selecting drug-resistant bacilli. "Ping-pong reinfection" between newly diagnosed and previously treated LL patients is stopped. Then transmission declines rapidly. Otherwise ping-pong reinfection between persons with polar LL genomes, especially within households, can maintain transmission indefinitely. Multi-case LL households and previously treated LL patients requiring prolonged anti-microbial protection are each an important source of transmission. For example, in Salaunikhurd village of Chhattisgarh, India, with multi-case LL households and highly bacillated but previously treated patients, the incidence rate of new cases over 4 years was as high as 10,000/million/year (100/10,000 persons/yr). (8)
The multi-case families in Salaunikhurd village had average cash incomes of the order of only 4 US cents/person/day. That is cents, not dollars. 29% of the villagers were illiterate. These people do not have a prominent voice, nor access to reliable scientific information. They are poorly placed to demand the anti-microbial protection they need. As privileged persons with scientific knowledge, we can choose to speak out for them and ensure prolonged anti-microbial protection, together with the mass multi-drug administration that was so highly impactful in FS Micronesia. (7) Science and compassion both point in the same direction, as do the noble values of our community.
Fact-based epidemiology, combined with respect for the human dignity and rights of patients in endemic areas, enables effective action with measurable epidemiological impact. It can be helpful to piece together epidemiological clues, while looking beyond selective non-publication (e.g., of findings regarding the repeatedly disappointing impact of single dose rifampicin among household contacts).
India is moving in the right direction by increasingly relying on smear microscopy to detect the few but very important "de novo" LL cases. Such cases, whether newly infected or re-infected, are often missed by health workers because the patients can feel almost no discomfort and often show no skin patches.(8) We could applaud such productive moves by India, and allow elbow room for endemic countries to succeed.
A prerequisite for technical advice could usefully be that it has been shown to produce strong epidemiological impact. Otherwise ineffective technical advice, with little or no impact on transmission or even with selection of drug-resistant mutant bacilli, could displace more effective approaches.
Is it a bad idea to learn from highly effective interventions demonstrated by successful projects in endemic countries? Are we against respect for the human dignity of patients? Are we against rapid decline in transmission?
1. Davey TF, Rees RJ. The nasal dicharge in leprosy: clinical and bacteriological aspects. Lepr Rev. 1974 Jun;45(2):121-34.
2. Balagon MVF, Gelber RH, Abalos RM, Cellona RV. Reactions following completion of 1 and 2 year multidrug therapy (MDT) Am J Trop Med Hyg 2010 Sep;83(3):637-44. doi: 10.4269/ajtmh.2010.09-0586, reviewed and analysed further in 2a. Almeida J, Are we against preventing painful ENL neuritis? LML 26 March 2023
3. Yosephine P. Report presented at WHO Global Consultation with NLP Managers, Partners, and Affected Persons on Global Leprosy Strategy 2021-2030. 28 October 2020
4. Norman G, Bhushanam JDRS, Samuel P. Trends in leprosy over 50 years in Gudiyatham Taluk, Vellore, Tamil Nadu. Ind J Lepr 2006. 78(2): 167-185. reviewed and analysed further in: 3a. Almeida J. Karigiri, India: How transmission rapidly was reduced in a low-income population. LML 29 Oct 2020
5. Tonglet R, Pattyn SR, Nsansi BN et al. The reduction of the leprosy endemicity in northeastern Zaire 1975/1989 J.Eur J Epidemiol. 1990 Dec;6(4):404-6 reviewed in: 4a. Almeida J. Reducing transmission in poor hyperendemic areas - evidence from Uele (DRC). LML 29 Nov 2019
6. Li HY, Weng XM, Li T et al. Long-Term Effect of Leprosy Control in Two Prefectures of China, 1955-1993. Int J Lepr Other Mycobact Dis. 1995 Jun;63(2):213-221. reviewed & analysed further in: 5a. Almeida J. What really happened in Shandong? LML 16 Nov 2019
7. WORKSHOP ON THE PREVENTION OF LEPROSY, POHNPEI, FEDERATED STATES OF MICRONESIA. 25-27 MAY 1999 sponsored by the Sasakawa Memorial Health Foundation Tokyo, Japan and the Western Pacific Regional Office of the World Health Organization. Int J Lepr, 67 (4) (SUPPLEMENT)
8. Gitte S, Rewaria L, Santaram V, Jamil S. Descriptive Study of High Leprosy Endemic Pockets and Exploring Occurrence Factors of Multicase Families in the Village
of Salaunikhurd of Chhattisgarh State. Int J Med. Public Health. 2021; 11(2):113-117
LML - S Deepak, B Naafs, S Noto and P Schreuder
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