Leprosy epidemiology and demographics: Difference between revisions

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==Overview==
==Overview==
Current [[prevalence]] rate of leprosy per 100,000 is 3.7. The disease is more prevalent in [[endemic]] areas, which represent a potential source of spread of the disease to the rest of the world.


==Epidemiology and Demographics==
==Epidemiology and Demographics==
In 1990, the WHO defined a goal of eliminating leprosy as a public health issue within 10 years. Between the years of 1985 and 2010, the number of registered cases of leprosy fell from 5.4 million to 244,796, with [[prevalence]] rate per 100,000 falling from 211 to 3.7. However this [[prevalence]] is very variable according to the region, since most reported cases come from developing countries, such as India, Brazil and Indonesia. Efforts have been made to decrease the number of cases in [[endemic]] areas and to avoid [[transmission]] of the disease to other parts of the world, since international travel represents an important vehicle of the [[bacteria]] into other parts of the globe. This [[transmission]] has such impact that among the cases reported annually in the United States, 75% occur in emigrants.


===Incidence===
===Incidence===
Although annual [[Incidence (epidemiology)|incidence]] is important as a measure of [[transmission]], it is difficult to measure the leprosy [[incidence]] due to its long [[incubation period]], delays in [[diagnosis]] after onset of the disease and the lack of laboratory tools to detect leprosy in its very early stages.
Due to the long [[incubation period]], delay in [[diagnosis]], and lack of laboratory infrastructures it is difficult to measure the true [[incidence]] of leprosy.


Worldwide, two to three million people are estimated to be permanently disabled because of leprosy. India has the greatest number of cases, with Brazil second and Myanmar third.
Two to three million people are estimated to be permanently disabled due to leprosy. India has the greatest number of cases, followed by Brazil and Myanmar.


In 1999, the world [[Incidence (epidemiology)|incidence]] of Hansen's disease was estimated to be 640,000; in 2000, 738,284 cases were identified. In 1999, 108 cases occurred in the United States. In 2000, the [[World Health Organization]] ([[WHO]]) listed 91 countries in which leprosy is [[endemic (epidemiology)|endemic]].  
In 1999, the world [[Incidence (epidemiology)|incidence]] of leprosy was estimated to be 640,000; in 2000, 738,284 cases were identified. In 1999, 108 cases occurred in the United States. In 2000, the [[World Health Organization]] ([[WHO]]) listed 91 countries in which leprosy was [[endemic (epidemiology)|endemic]].  


India, Myanmar and Nepal contained 70% of cases. In 2002, 763,917 new cases were detected worldwide, and in that year the [[WHO]] listed Brazil, Madagascar, Mozambique, Tanzania and Nepal as having 90% of leprosy cases.
According to the [[WHO]], the number of new cases has decreased by approximately 107,000 cases (or 21%) from 2003 to 2004. This decreasing trend has been consistent for the past three years.
 
According to recent figures from the [[WHO]], new cases detected worldwide have decreased by approximately 107,000 cases (or 21%) from 2003 to 2004. This decreasing trend has been consistent for the past three years.


===Prevalence===
===Prevalence===
Registered prevalence is a useful proxy indicator of the disease burden as it reflects the number of active leprosy cases diagnosed with the disease and retrieving treatment with MDT at a given point in time.  
Registered [[prevalence]] reflects the number of active leprosy cases [[diagnosis|diagnosed]] with the disease and retrieving treatment with multi-drug therapy (MDT) at a given point in time. In fact, the global registered prevalence of leprosy at the beginning of 2012 was 181,941; 219,075 new cases were detected during 2011.


The prevalence rate is defined as the number of cases registered for MDT treatment among the population in which the cases have occurred, again at a given point in time.<ref name=WHO_1985>{{cite journal |author= |title=Epidemiology of leprosy in relation to control. Report of a WHO Study Group |journal=World Health Organ Tech Rep Ser |volume=716 |issue= |pages=1-60 |year=1985 |pmid=3925646}}</ref>
As reported to the [[WHO]] by 105 countries and territories in 2012 the global registered [[prevalence]] of leprosy at the beginning of 2012 was 181,941 cases. <ref name=WHO>{{cite web | title =  
global leprosy situation, 2012 | url = http://www.who.int/wer/2012/wer8734.pdf?ua=1 }}</ref> New case detection during the previous year (2011) was 219,075. The number of new cases detected annually continues to increase in all regions other than the Americas and African Regions. The significant decline in the African Region reflects the low number of reports submitted, particularly from member states reporting high number of new cases in the past. Increased coverage along with provision of better services in South Sudan and Somalia were the main factors that led to detection of more new cases in the Eastern Mediterranean Region.<ref name=WHO>{{cite web | title =  
global leprosy situation, 2012 | url = http://www.who.int/wer/2012/wer8734.pdf?ua=1 }}</ref>


New case detection is another indicator of the disease that is usually reported by countries on an annual basis. It includes cases diagnosed with onset of disease in the year in question (true incidence) and a large proportion of cases with onset in previous years (termed a backlog prevalence of undetected cases).  
The [[prevalence]] of Leprosy in the United States is believed to be rising and underreported. There are a rising number of cases worldwide, though pockets of high [[prevalence]] continue in certain areas such as Brazil, South Asia (India, Nepal), some parts of Africa (Tanzania, Madagascar, Mozambique) and the western Pacific.


The new case detection rate (NCDR) is defined by the number of newly detected cases, previously untreated, during a year divided by the population in which the cases have occurred.
[[Image:Leprosy Epidemiology 2.png|left|600px|thumb|Trends in the detection of new cases of leprosy, by WHO region, 2004-2011]]<br clear="left"/>


In addition, the global registered prevalence of HD was 286,063 cases; 407,791 new cases were detected during 2004.
''The above image shows an increase in the number of new cases detected from 2010 to 2011, with exception of the Americas and African regions''


Hansen's disease is tracked by the [[Centers for Disease Control and Prevention]] (CDC). Its [[prevalence]] in the United States is believed to be rising and underreported.<ref>{{cite news | author = Levis W | date = 2007-05-20 | url = http://transcripts.cnn.com/TRANSCRIPTS/0705/20/ldtw.01.html |title = Leprosy rising | work = CNN}}</ref> There are a rising number of cases worldwide, though pockets of high prevalence continue in certain areas such as Brazil, South Asia (India, Nepal), some parts of Africa (Tanzania, Madagascar, Mozambique) and the western Pacific.
[[Image:Leprosy epidemiology 3.png|left|600px|thumb|Prevalence of leprosy and number of new cases detected in 105 countries or territories, by WHO Region, 2011 and first quarter of 2012]]<br clear="left"/>


As reported to [[WHO]] by 115 countries and territories in 2006, and published in the Weekly Epidemiological Record the global registered [[prevalence]] of leprosy at the beginning of the year was 219,826 cases. <ref name=WHO_2006>{{cite journal | author = | title = Global leprosy situation, 2006 | journal = Weekly Epidemiological Record | year = 2006 | volume = 81 | number = 32 | pages =309&ndash;16 | url= http://www.who.int/lep/resources/wer8132.pdf}}</ref> New case detection during the previous year (2005 - the last year for which full country information is available) was 296,499. The reason for the annual detection being higher than the prevalence at the end of the year can be explained by the fact that a proportion of new cases complete their treatment within the year and therefore no longer remain on the registers. The global detection of new cases continues to show a sharp decline, falling by 110,000 cases (27%) during 2005 compared with the previous year.
''The above image shows prevalence of leprosy at the beginning of 2012. In 2011, the number of new cases, from 105 countries was 219,075. At the beginning of 2012, the registered prevalence was 181,941''
 
{| class = "prettytable" style = "float:center; font-size:85%; margin-left:15px"
| + colspan="7" | '''Table 1:''' Prevalence at beginning of 2006, and trends in new case detection 2001-2005, excluding Europe
|-
!rowspan=2|Region
!colspan=1 width=160|Registered Prevalence
(rate/10,000 pop.)
!colspan=5 width=400|New Case Detection during the year
|-
! Start of 2006 !! 2001 !! 2002 !! 2003 !! 2004 !! 2005
|-
 
| align="left" | Africa
| 40,830 (0.56) || 39,612 || 48,248 || 47,006 || 46,918 || 42,814
|-
| align="left" | Americas
| 32,904 (0.39) || 42,830 || 39,939 || 52,435 || 52,662 || 41,780
|-
| align="left" | South-East Asia
| 133,422 (0.81) || 668,658 || 520,632 || 405,147 || 298,603 || 201,635
|-
| align="left" | Eastern Mediterranean
| 4,024 (0.09) || 4,758 || 4,665 || 3,940 || 3,392 || 3,133
|-
| align="left" | Western Pacific
| 8,646 (0.05) || 7,404 || 7,154 || 6,190 || 6,216 || 7,137
|-
|- style="border: 1px solid #BFA3A3; margin: auto" bgcolor="#F5FFFC" | background:#F2CECE
| align="left" |Totals
| 219,826 || 763,262 || 620,638 || 514,718 || 407,791 || 296,499
|}
'''Table 1''' shows that global annual detection has been declining since 2001. The African region reported an 8.7% decline in the number of new cases compared with 2004. The comparable figure for the Americas was 20.1%, for South-East Asia 32% and for the Eastern Mediterranean it was 7.6%. The Western Pacific area, however, showed a 14.8% increase during the same period.
<br clear="left"/>
{| class = "prettytable" style = "float:center; font-size:85%; margin-left:15px"
| + colspan="7" | '''Table 2:''' Prevalence and Detection, countries still to reach elimination
|-
!rowspan=2|Countries
!colspan=3 width=240|Registered Prevalence
(rate/10,000 pop.)
!colspan=3 width=240|New Case Detection
(rate/100,000 pop.)
|-
! Start of 2004 !! Start of 2005 !! Start of 2006 !! During 2003 !! During 2004 !! During 2005
|-
| align="left" |Brazil
| 79,908 (4.6) || 30,693 (1.7) || 27,313 (1.5) || 49,206 (28.6) || 49,384 (26.9) || 38,410 (20.6)
|-
| align="left" |Democratic Republic of the Congo
| 6,891 (1.3) || 10,530 (1.9) || 9,785 (1.7) || 7,165 (13.5) || 11,781 (21,1) || 10,737 (18.7)
|-
| align="left" |Madagascar
| 5,514 (3.4) || 4,610 (2.5) || 2,094 (1.1) || 5,104 (31.1) || 3,710 (20.5) || 2,709 (14.6)
|-
| align="left" |Mozambique
| 6,810 (3.4) || 4,692 (2.4) || 4,889 (2.5) || 5,907 (29.4) || 4,266 (22.0) || 5,371 (27.1)
|-
| align="left" |Nepal
| 7,549 (3.1) || 4,699 (1.8) || 4,921 (1.8) || 8,046 (32.9) || 6,958 (26.2) || 6,150 (22.7)
|-
| align="left" |Tanzania
| 5,420 (1.6) || 4,777 (1.3) || 4,190 (1.1) || 5,279 (15.4) || 5,190 (13.8) || 4,237 (11.1)
|- style="border: 1px solid #BFA3A3; margin: auto" bgcolor="#F5FFFC" | background:<tt>#F2CECE
| align="left" |Totals
| 112,092 || 60,001 || 53,192 || 80,707 || 81,289 || 67,614
|}
 
'''Table 2''' shows the leprosy situation in the six major countries which have yet to achieve the goal of elimination at the national level. It should be noted that: a) Elimination is defined as a prevalence of less than 1 case per 10,000 population; b) Madagascar reached elimination at the national level in September 2006; and c) Nepal detection reported from mid-November 2004 to mid-November 2005.
<br clear="left"/>


Due to the rising numbers, several support groups exist, the headquarters of which is currently in Lynbrook, NY and headed by Brian Marasco, leprosy survivor.  
Due to the rising numbers, several support groups exist, the headquarters of which is currently in Lynbrook, NY and headed by Brian Marasco, leprosy survivor.  


[[Image:Lepra 2003.png|left|250px|thumb|World distribution of leprosy, 2003.]]<br clear="left"/>
[[Image:Leprosy geographic prevalence.png|left|500px|thumb|Leprosy prevalence rates, data reported to WHO as of beginning January 2011]]<br clear="left"/>


Endemic countries also report the number of new cases with established disabilities at the time of detection, as an indicator of the backlog prevalence. However, determination of the time of onset of the disease is generally unreliable, is very labour-intensive and is seldom done in recording these statistics.
[[Endemic]] countries also report the number of new cases with established disabilities at the time of detection, as an indicator of the backlog [[prevalence]]. However, determination of the time of onset of the disease is generally unreliable, is very labour-intensive and is seldom done in recording these statistics.


===Elimination of Leprosy as a Public Health Problem===
===Elimination of Leprosy as a Public Health Problem===
In 1991 WHO's governing body, the World Health Assembly (WHA) passed a resolution to eliminate leprosy by the year 2000. Elimination of leprosy is defined as a prevalence rate of less than 1 case per 10 000 persons. The target was achieved on time and the widespread use of MDT reduced the disease burden dramatically.
In 1991 [[WHO]]'s governing body, the World Health Assembly (WHA) passed a resolution to eliminate leprosy by the year 2000. Elimination of leprosy is defined as a [[prevalence]] rate of less than 1 case per 10 000 persons. The target was achieved on time and the widespread use of multi drug [[therapy]] reduced the [[disease]] burden dramatically.
*Over the past 20 years, more than 14 million leprosy patients have been cured, about 4 million since 2000.
* Over the past 20 years, more than 14 million leprosy patients have been cured, about 4 million since 2000.
*The prevalence rate of the disease has dropped by 90% – from 21.1 per 10 000 inhabitants to less than 1 per 10 000 inhabitants in 2000.
* The [[prevalence]] rate of the disease has dropped by 90% – from 21.1 per 10 000 inhabitants to less than 1 per 10 000 inhabitants in 2000.
*Dramatic decrease in the global disease burden: from 5.2 million in 1985 to 805 000 in 1995 to 753 000 at the end of 1999 to 181 941 cases at the end of 2011.
* Dramatic decrease in the global [[disease]] burden: from 5.2 million in 1985 to 805 000 in 1995 to 753 000 at the end of 1999 to 181 941 cases at the end of 2011.
*Leprosy has been eliminated from 119 countries out of 122 countries where the disease was considered as a public health problem in 1985.
* Leprosy has been eliminated from 119 countries out of 122 countries where the disease was considered as a public health problem in 1985.
*So far, there has been no resistance to antileprosy treatment when used as MDT.
* So far, there has been no [[resistance]] to antileprosy treatment when used as multi drug [[therapy]].
*Efforts currently focus on eliminating leprosy at a national level in the remaining endemic countries and at a sub-national level from the others.
* Efforts currently focus on eliminating leprosy at a national level in the remaining [[endemic]] countries and at a sub-national level from the others.


==References==
==References==
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[[Category:Disease]]
[[Category:Disease]]
[[Category:Dermatology]]
[[Category:Dermatology]]
[[Category:Infectious disease]]
 
[[Category:Tropical disease]]
[[Category:Tropical disease]]
[[Category:Leprosy]]
[[Category:Leprosy]]

Latest revision as of 18:10, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

Current prevalence rate of leprosy per 100,000 is 3.7. The disease is more prevalent in endemic areas, which represent a potential source of spread of the disease to the rest of the world.

Epidemiology and Demographics

In 1990, the WHO defined a goal of eliminating leprosy as a public health issue within 10 years. Between the years of 1985 and 2010, the number of registered cases of leprosy fell from 5.4 million to 244,796, with prevalence rate per 100,000 falling from 211 to 3.7. However this prevalence is very variable according to the region, since most reported cases come from developing countries, such as India, Brazil and Indonesia. Efforts have been made to decrease the number of cases in endemic areas and to avoid transmission of the disease to other parts of the world, since international travel represents an important vehicle of the bacteria into other parts of the globe. This transmission has such impact that among the cases reported annually in the United States, 75% occur in emigrants.

Incidence

Due to the long incubation period, delay in diagnosis, and lack of laboratory infrastructures it is difficult to measure the true incidence of leprosy.

Two to three million people are estimated to be permanently disabled due to leprosy. India has the greatest number of cases, followed by Brazil and Myanmar.

In 1999, the world incidence of leprosy was estimated to be 640,000; in 2000, 738,284 cases were identified. In 1999, 108 cases occurred in the United States. In 2000, the World Health Organization (WHO) listed 91 countries in which leprosy was endemic.

According to the WHO, the number of new cases has decreased by approximately 107,000 cases (or 21%) from 2003 to 2004. This decreasing trend has been consistent for the past three years.

Prevalence

Registered prevalence reflects the number of active leprosy cases diagnosed with the disease and retrieving treatment with multi-drug therapy (MDT) at a given point in time. In fact, the global registered prevalence of leprosy at the beginning of 2012 was 181,941; 219,075 new cases were detected during 2011.

As reported to the WHO by 105 countries and territories in 2012 the global registered prevalence of leprosy at the beginning of 2012 was 181,941 cases. [1] New case detection during the previous year (2011) was 219,075. The number of new cases detected annually continues to increase in all regions other than the Americas and African Regions. The significant decline in the African Region reflects the low number of reports submitted, particularly from member states reporting high number of new cases in the past. Increased coverage along with provision of better services in South Sudan and Somalia were the main factors that led to detection of more new cases in the Eastern Mediterranean Region.[1]

The prevalence of Leprosy in the United States is believed to be rising and underreported. There are a rising number of cases worldwide, though pockets of high prevalence continue in certain areas such as Brazil, South Asia (India, Nepal), some parts of Africa (Tanzania, Madagascar, Mozambique) and the western Pacific.

Trends in the detection of new cases of leprosy, by WHO region, 2004-2011


The above image shows an increase in the number of new cases detected from 2010 to 2011, with exception of the Americas and African regions

Prevalence of leprosy and number of new cases detected in 105 countries or territories, by WHO Region, 2011 and first quarter of 2012


The above image shows prevalence of leprosy at the beginning of 2012. In 2011, the number of new cases, from 105 countries was 219,075. At the beginning of 2012, the registered prevalence was 181,941

Due to the rising numbers, several support groups exist, the headquarters of which is currently in Lynbrook, NY and headed by Brian Marasco, leprosy survivor.

Leprosy prevalence rates, data reported to WHO as of beginning January 2011


Endemic countries also report the number of new cases with established disabilities at the time of detection, as an indicator of the backlog prevalence. However, determination of the time of onset of the disease is generally unreliable, is very labour-intensive and is seldom done in recording these statistics.

Elimination of Leprosy as a Public Health Problem

In 1991 WHO's governing body, the World Health Assembly (WHA) passed a resolution to eliminate leprosy by the year 2000. Elimination of leprosy is defined as a prevalence rate of less than 1 case per 10 000 persons. The target was achieved on time and the widespread use of multi drug therapy reduced the disease burden dramatically.

  • Over the past 20 years, more than 14 million leprosy patients have been cured, about 4 million since 2000.
  • The prevalence rate of the disease has dropped by 90% – from 21.1 per 10 000 inhabitants to less than 1 per 10 000 inhabitants in 2000.
  • Dramatic decrease in the global disease burden: from 5.2 million in 1985 to 805 000 in 1995 to 753 000 at the end of 1999 to 181 941 cases at the end of 2011.
  • Leprosy has been eliminated from 119 countries out of 122 countries where the disease was considered as a public health problem in 1985.
  • So far, there has been no resistance to antileprosy treatment when used as multi drug therapy.
  • Efforts currently focus on eliminating leprosy at a national level in the remaining endemic countries and at a sub-national level from the others.

References

  1. 1.0 1.1 "global leprosy situation, 2012" (PDF).


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