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118 THIRD WHO REPORT ON NEGLECTED TROPICAL DISEASES
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4.9 Leishmaniases
Introduction
The leishmaniases are a range of diseases caused by protozoan parasites transmitted
through the bites of infected female sandflies. Visceral leishmaniasis, also known as
kala-azar, is usually fatal within 2 years if left untreated. After treatment, visceral leishmaniasis
sometimes evolves into a cutaneous form, known as post-kala-azar dermal leishmaniasis, cases
of which may serve as sources of infection for sandflies and thus maintain transmission (1).
Cutaneous leishmaniasis is the most prevalent form, causing ulcers that heal spontaneously.
Mucocutaneous leishmaniasis invades the mucous membranes of the upper respiratory tract,
causing gross mutilation by destroying tissues in the nose, mouth and throat.
Investment case
Visceral leishmaniasis tends to be highly focalized among the lowest socioeconomic
groups. In Bihar, India, 83% of households in communities with high attack rates
belonged to the two lowest quintiles (the poorest 40%) of the wealth distribution. 1 Studies
from several of the highest burden countries show that even when diagnosis and medicines
are provided free of charge, 25–75% of affected households experience some type of financial
catastrophe. 2,3,4,5,6 Other studies are summarized in a review of the burden of visceral
leishmaniasis in South Asia. 7 Free diagnosis and treatment (at point of care) is a minimum
requirement to avoid catastrophic health expenditure, but other forms of social protection
will also be required to prevent impoverishment. In Nepal, in addition to free diagnosis
and treatment, kala-azar patients receive cash transfers contingent upon completion of
treatment, to cover transport and nutrition costs. 8
Cutaneous leishmaniasis has been less studied from an economic perspective despite the
oft-cited link between poverty and disease. 9 The cost-effectiveness of interventions was not
specifically discussed in the second edition of the Disease Control Priorities Project in
2006. The difficulty with assessing the cost-effectiveness is that this form of the disease is
not fatal and disability weights may not fully reflect the social stigmatization associated
with disfigurement. Nonetheless, a few economic evaluations have emerged since 2006,
suggesting that interventions for early diagnosis and treatment could be highly costeffective
but that (late) diagnosis and treatment in complex emergency settings may not