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Is leprosy chemoprophylaxis necessary at all?
- Mohammad M Rahman (5 April 2008)
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Stigma remains a major issue
- Iain B Craighead (14 April 2008)
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Mohammad M Rahman, MBBS, LMCC Residency applicant
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F Johannes Moet and colleagues’ research on rifampicin chemoprophylaxis on leprosy found benefit at two years after rifampicin, but did not find any statistically significant difference between rifampicin chemoprophylaxis and placebo treatment in the third and fourth years after rifampicin treatment. This is significant because M. leprae multiplies very slowly and the incubation period of leprosy is about five years, but can be up to 20 years [1]. Therefore, whether the absence of clinical cases of leprosy at two years after rifampicin treatment is due to rifampicin chemoprophylaxis or just due to sub-clinical infection within the incubation period cannot be established. F Johannes Moet and colleagues realize this and rightly state that after four years’ follow-up they cannot yet establish to what extent there is a true prevention of new cases of leprosy by intervention with rifampicin, and there may be merely a delay in the occurrence of disease, which can only be confirmed through a longer observation period. F Johannes Moet and colleagues, therefore, could not establish that rifampicin chemoprophylaxis is any better than no chemoprophylaxis at all, since their study extent was only four year, and chemoprophylaxis was no better than placebo at that point. Even if any benefit of rifampicin chemoprophylaxis really exists, it is not more than 50% under routine condition [2]. In the absence of any long-term chemoprophylaxis benefit, after the benefit has waned, the high- risk individual could immediately be re-infected with M. leprae as long as transmission persists [3]. F Johannes Moet and colleagues’ finding that patients with low risk for leprosy, on the basis of physical distance, genetic relationship, age, and leprosy classification [4], benefited more from rifampicin chemoprophylaxis is not surprising because contacts who are not at close physical distance from the patient are not close contacts at all. Leprosy, after all, is not highly infectious [5] and is transmitted by close contact via droplets from the nose and mouth of untreated patients with severe disease [5]. The contribution of close household contacts to the total number of new leprosy cases in a population is about 30% and the chemoprophylaxis benefit of these household contacts is only 15% [2]. Epidemiological data suggest that, to prevent a single case of leprosy, hundreds or even thousands of contacts need to be treated [2]. The cost and the operational difficulties to apply chemoprophylaxis to a large number of population will be extremely high, although the yield will be limited [2,6,7]. World Health Organization (WHO) does not have a chemoprophylaxis strategy for leprosy. WHO stresses that patients are no longer infectious to others after the first dose of Multi Drug Therapy (MDT) [1] currently approved by WHO. WHO strategy of promoting early detection, diagnosis and treatment of leprosy, not chemoprophylaxis, seems right at this time. References: 1. www.who.int/mediacentre/factsheets/fs101/en/index.html 2. Noordeen SK, (2000) Prophylaxis - scope and limitations. Leprosy Review 71: S16-S20. 3. Baohong Ji, (2002) Bactériologie et Hygiène, Faculté de Médecine Pitié-Salpêtrière, Paris, France. Scientific Working Group, Report on Leprosy, 26–28 November 2002, Geneva, Switzerland, Copyright © World Health Organization on behalf of the Special Programme for Research and Training in Tropical Diseases, 2003 (http://www.who.int/tdr/publications/publications/swg_leprosy.htm) 4. Moet FJ, Pahan D, Schuring RP, Oskam L, Richardus JH. Physical distance, genetic relationship, age, and leprosy classification are independent risk factors for leprosy in contacts of patients with leprosy. J Infect Dis 2006;193:346-53.[CrossRef][ISI][Medline] 5. http://www.who.int/topics/leprosy/en/ 6. Diletto C, Blanc L, (2000) Leprosy chemoprophylaxis in Micronesia. Leprosy Review 71: S21-S25. 7. Nguyr LN, Cartel JL, Grosset JH, (2000) Chemoprophylaxis of leprosy in the Southern Marquesas with a single 25 mg/kg dose of rifampicin. Results after 10 years. Leprosy Review 71: S33-S36. Competing interests: None declared |
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Iain B Craighead, Medical Superintendent Green Pastures Leprosy Hospital, Pokhara, Nepal
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Whilst I do welcome the paper by Moet and colleagues (1), Professor Cairns Smith (2) is right to raise the issue of stigma. Stigma remains a major issue here in Nepal. Those most likely to suffer discrimination are those whom society regards as less productive: elderly women and girls in their early teens. After hospital admission families often fail to come and collect their relatives from hospital, and we then have to embark on a delicate fact finding and education process to try and reinterate these patients back into their own families and communities. If we were also to suggest that family members and neighbours take a form of chemoprphylaxis there is a significant risk that we may inflame an already delicate situation. If chemoprophylaxis is to become a facet in the drive towards leprosy elimination then the benefits will have to outweigh the increase in stigma that may result. With a single dose of rifampacin the benefits probably remain insufficient. 1. Moet FJ, Pahan D, Oskan L, Richardus JH. Effectiveness of single dose rifampacin in preventing leprosy in close contacts of patients with newly diagnosed leprosy: cluster randomised controlled trial. BMJ 2008; 336:761-764 2. Smith WCS. Chemoprophylaxis in the prevention of leprosy. BMJ 2008;336:730-1 Competing interests: None declared |
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