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112 THIRD WHO REPORT ON NEGLECTED TROPICAL DISEASES
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Burden and distribution
Since 2009, fewer than 10 000 new cases have been reported annually for the first time in
30 years, with 6314 new cases in 2013. This trend represents a decrease of 76% since 2000. The
number of cases reported annually is considered to be a fraction of the real burden. According
to the latest (2011) estimates (1), the incidence could be around 20 000 cases a year.
Human African trypanosomiasis affects impoverished rural areas of sub-Saharan Africa, where
it coexists with animal trypanosomiasis. The presence of human and animal trypanosomiasis
impedes development in these communities and traps people in a cycle of poverty.
Approximately 70 million people distributed over an area of 1.55 million km 2 are at risk
(2). Advances in controlling the disease made during the past decade have achieved an
important decrease in its burden, but control and research efforts must continue and be based
on sustainable public-health objectives, not only on the actual burden of the disease. Fig. 4.8.1
shows the decline in the numbers of new cases reported globally from 1990 to 2013.
Fig. 4.8.1
Number of human African trypanosomiasis cases reported to
WHO,1990–2013
Number of cases reported
Thousands
40
35
30
25
20
15
10
5
0
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
Year
T.b. gambiense
T.b. rhodesiense
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
12 756 10 987 14 088 16 607 23 266 23 671 28 736 36 585 37 385 27 862 25 865 26 117
1933 1219 1147 831 711 935 591 592 606 619 709 755
T.b. gambiense
T.b. rhodesiense
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
23 836 19 963 17 130 15 644 11 382 10 473 10 388 9 685 6 978 6 637 7 106 6 228
617 536 552 710 453 305 259 190 156 113 110 86