Leprosy Mailing List – November 8, 2019
Ref.: (LML) What really happened in Shandong ?
From: Paul Fine, London, UK
Dear Pieter,
Readers may have been interested to read repeated references in LML to dramatically effective leprosy control in Shandong Province of China.
For example:
". Shandong demonstrated that near-zero transmission can be achieved within a surprisingly short duration…Shandong protected LL patients with prolonged anti-microbial treatment. That allowed Shandong to shut down a major source of concentrated viable bacilli. Shandong then achieved a 20% / year decline in incidence rate." (Almeida J, LML 04/11/19)
Similar statements by the same correspondent appeared in LML on 18 September and 11 October. This prompted me to examine the cited publication (1), which is available on: http://ila.ilsl.br/pdfs/v63n2a03.pdf
My interpretation is rather different to that expressed in LML. While it is apparent that leprosy declined rapidly in Shandong province, there is little if any evidence that this was directly attributable to protection of "LL patients with prolonged antimicrobial treatment".
Consider the following:
· - Leprosy was declining dramatically from 1955 (the earliest data shown – see Figure 3), thus effectively from the start of leprosy control if not before ("organised control" began in Shandong with dapsone in the 1960s, rifampicin was introduced only in 1979, and MDT in 1986 - see page 213).
· - The paper states that "Before the implementation of MDT, Weifang [=Shandong] already kept leprosy under control, reducing the detection rate …. since the 1960s" (p 214).
· - The paper notes that there were no child cases detected since 1985 "due to the interruption of transmission several decades ago" (p 216)
· - The proportion MB rose to 80 % in the 1980s, consistent with cessation (or near cessation) of transmission long before and consequent increasing predominance of long incubation period forms of the disease (Figure 5)
Several features of Shandong are consistent with this early decline of leprosy:
· - Even in 1955 the case detection rate was only about 3.5 per 10,000. By 1980 it was less than 1 per 100,000 ! (Figure 3)
· - It is a semi-urban area in northern China, latitude c. 17 degrees, similar to southern Europe
· - It had a dramatic improvement in socio-economic indicators, low infant mortality and high life expectancy (Table 1) – characteristics associated with leprosy decline in several societies. This is acknowledged in the paper ("since 1978…. Weifang has experienced rapid growth of average annual income…" [P 217])
The simplest interpretation of these several observations is that Shandong was similar to many populations in the world which have undergone considerable socio-economic improvement and in which leprosy declined to vanishingly low levels – even before the advent of any chemotherapy. In another publication (2) the authors explicitly compared the Shandong pattern to that in Norway, where leprosy declined dramatically to zero before the advent of dapsone (3).
Pointing out that there is little evidence that leprosy's decline in Shandong was attributable to prolonged treatment of LL patients is in no way meant to question the utility of chemotherapy or of MDT – which is obviously essential for leprosy treatment and control.
But the observation does raise several issues:
· - The Shandong experience provides yet another example of important background trends and the powerful negative association between socio-economic level and leprosy.
· - It is hard to show the population impact of case finding and treatment on leprosy incidence. It must have some effect – but this has proven difficult to demonstrate convincingly given
(a) the absence of appropriate comparable control populations,
(b) the long incubation periods and hence delayed effects of interventions,
(c) the fact that much transmission by clinical cases occurs before they are detected, and
(d) the fact that we still do not fully understand the natural history of leprosy, and it may be that we are missing some sources of transmission in endemic communities.
· - One should look critically at evidence.
Readers are encouraged to look at the Li et al papers and make up their minds themselves.
Paul Fine
References:
1. 1. Li H-Y, Wang X-M, Li T, Zheng D-Y, Mao Z-M, Ran S-P, Liu F-W. Long term effect of leprosy control in two prefectures of China, 1955 – 1993. Int J Leprosy 1995; 63: 213 – 221 (http://ila.ilsl.br/pdfs/v63n2a03.pdf)
2. 2. Li H-Y, Pan Y-L, Yang W. Leprosy control in Shandong Province, China. 1955 – 1983; some epidemiological features. Int J Leprosy 1985; 53: 79 – 85. (http://ila.ilsl.br/pdfs/v53n1a14.pdf)
3. 3. Irgens L. Leprosy in Norway. Leprosy Review 1980; 51 (supplement 1): 1-130. (http://leprev.ilsl.br/pdfs/1980/v51s1/pdf/pdf_full/v51s1.pdf)
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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