The major efforts towards onchocerciasis control now are, of course,
based on the use of ivermectin in mass distribution programmes throughout
the endemic countries. Three Regional Programmes have been established
that coordinate control of onchocerciasis in 33 of the 34 endemic countries;
the 34th, Yemen, has an independent control programme.
The 6 countries of the Americas with onchocerciasis now coordinate their
control efforts through the Onchocerciasis Elimination Program in the Americas
(OEPA) with funds from the respective Governments, Non-Governmental Developmental
Organizations (NGDOs) and the InterAmerican Development Bank (IDB). Currently
there are programmes active in all 6 countries, and 70% of all known positive
cases in the Americas have been treated at least once (some up to 8 times).
The 11-country Onchocerciasis Control Programme (OCP) in West Africa has
virtually eliminated the parasite reservoir from the original 7 countries,
first by the aerial application of insecticides to the breeding rivers of
the Simulium vectors and more recently through the use of ivermectin
both in persistent foci of the `core countries' and as the first-line approach
in the "extension areas" of the Programme. Currently ivermectin
distribution reaches approximately 2 million people annually in the OCP
area.
The African Programme for Onchocerciasis Control (APOC) is just getting
underway with support by the World Bank, WHO, UNDP, FAO and the 16 endemic
countries lying outside of the area of the OCP. This new organization will
consolidate and extend (with World Bank support of approximately US $120
million over 12 years) the considerable efforts already begun by NGDOs in
coordination with WHO and the Mectizan® Donation Program that is part
of the Task Force for Child Survival at the Carter Center (Atlanta).
All of these organizations are entirely dependent for their success on
the Mectizan® Donation Program created by Merck & Co., Inc. to provide
at no cost all of the ivermectin necessary to treat all patients with onchocerciasis
for as long as necessary to eliminate onchocerciasis as a public health
problem. Approximately 40 million doses of Mectizan® have been made
available to the programmes thus far, with an estimated 8 million people
having been treated at least once -- some annually for up to 5 or 6years.
The delivery of most of this ivermectin (outside of the OCP area) has been
effected by a consortium of NGDOs who have invested up to US$4million per
year in these programmes.
For the past several years, and for the foreseeable future, onchocerciasis
research supported by the WHO/TDR Programme has been almost exclusively
operational in nature and focused on ways to maximize the efficiency and
effectiveness of ivermectin delivery programmes.
Thus, in the first operational research studies techniques for rapidly
assessing the level of onchocercal endemicity (i.e., by palpating nodules
in a defined cohort of individuals in a community) were developed and have
been used to map onchocerciasis prevalence in many of the APOC countries.
This activity is still ongoing but is expected to be complete by the end
of 1996; all data is being managed in Geographical Information System (GIS)
format.
A second major focus of research interest has been defining the public
health and psychosocial importance of onchocercal skin disease and the best
way of treating it with ivermectin. Studies in 5 countries of Africa proved
onchocercal skin disease to be a grave psychosocial, stigmatizing, economy-draining
burden to individuals and communities; indeed, a much greater burden than
had been appreciated. As suggestive evidence had indicated that treatment
of such skin disease requires ivermectin to be administered more frequently
than once-yearly, a multi-site trial of ivermectin repeated at 3, 6 or 12-monthly
intervals is currently underway and anticipated for completion by the end
of 1996.
Finally, the other area of major operational research interest of importance
for sustainable ivermectin delivery programmes has been defining the best
techniques for involving communities in self-treatment strategies. It turns
out that community `coverage' by ivermectin delivery programmes is the variable
having the greatest impact on the ability of such programmes to interrupt
transmission of infection in a community. It also has been found that when
communities are left with supplies of ivermectin, they are able to reach
a higher proportion of individuals than most vertical programmes can, so
there is active research ongoing to determine the best strategies for developing
such sustainable community-based delivery programmes. This work, too, should
be complete by the end of 1996.
Thus, while it is recognized that effective vaccines are generally the
most efficient and cost-effective tools for preventing infectious diseases,
until such tools become available, activity in both the WHO-supported research
sphere and in the national and international control efforts will remain
on the use of ivermectin and on attempts to maximize the effectiveness of
this currently available control tool.