NAIROBI, KENYA (13 September 2012)=97A new analysis published today in
Science traces the recent global eradication of the deadliest of
cattle diseases, crediting not only the development of a new,
heat-resistant vaccine, but also the insight of local African herders,
who guided scientists in deciding which animals to immunize and when.
The study provides new insights into how the successful battle against
rinderpest in Africa, the last stronghold of the disease, might be
applied to similar diseases that today ravage the livestock
populations on which the livelihoods of one billion of the world=92s
poor depend.
Capable of wiping out a family=92s cattle in just a few days, rinderpest
was declared vanquished in May 2011. After smallpox, it is only the
second disease (and first livestock disease) ever to be eradicated
from the earth.
=93The elimination of rinderpest is an enormous triumph against a
disease that has plagued animals and humankind for centuries,=94 said
Jimmy Smith, director general of the International Livestock Research
Institute (ILRI). =93Science succeeded despite limited resources, and we
now know how. We are committed to applying the lessons in this study
to making progress against other similarly destructive livestock
diseases.=94
According to the analysis, which was conducted by international
scientists coordinated by ILRI, and published this week in Science,
the eradication of rinderpest happened thanks to the development of an
effective temperature-stable vaccine, collaborations between
veterinary health officials and cattle farmers to deliver those
vaccines, and reliance on the knowledge and expertise of the local
herders to determine the location and movement of outbreaks.
The cattle plague and its path of destruction
Rinderpest, known as “cattle plague” in English, is thought to have
had its origin in the dense cattle herds of Central Eurasia more than
two millennia ago and subsequently spread through warfare and trade to
cattle in Europe, Asia and eventually Africa. Caused by a virus
related to the one that causes measles and canine distemper,
rinderpest could infect cows, water buffalos and other cloven-hoofed
animals, leading to a high fever, severe diarrhea, then dehydration
and emaciation. The pathogen could kill 90 percent of a herd, wiping
out an entire farm=92s livestock in just a matter of days. There was no
treatment.
While rinderpest is not dangerous to human health, its impact on
humanity has been significant. Its path of destruction has been linked
to many history-changing events such as the fall of the Roman Empire,
the French Revolution and famines throughout Africa since the 19th
century. Indeed, nearly three-quarters of the rural poor and some
one-third of the urban poor depend on livestock for their food,
income, traction, manure or other services. Livestock provide poor
households with up to half their income and between 6 and 35 percent
of their protein consumption. The loss of a single milking animal can
affect a family=92s economic health, while depriving it of a primary
source of nutrition.
Road to eradication
The first major contributing factor to eradication, as identified by
the analysis, was a major improvement made to an existing rinderpest
vaccine. While the original vaccine was safe, effective, affordable,
and easy to produce, it needed to be refrigerated=97making it nearly
impossible to transport it to remote rural villages. With the
development of a new heat-resistant vaccine formulation in 1990 that
could be stored at 37=B0C for eight months, and in the field without
refrigeration for 30 days, scientists had a tool that would become the
cornerstone of the eradication effort in remote pastoral areas of
Africa.
But according to ILRI=92s Jeffrey Mariner, the analysis=92 lead author and
inventor of the temperature-stable rinderpest vaccine, it was the role
played by pastoralists that really turned rinderpest on its head.
As part of a public-private-community partnership, Mariner and
colleagues trained what they called community-based animal health
workers, or CAHWs=97local pastoralists who were willing to travel on
foot and able to work in remote areas=97on how to deliver the new
vaccine. These CAHWs carried the vaccine from herd to herd, immunizing
all the cattle in their communities.
The local herders performed as well, if not better, than did
veterinarians at vaccinating the herds=97in fact often achieving higher
than 80 percent herd immunity in a short time=97remarkable for a disease
that had plagued most of the world for millennia. Indeed, it turned
out that the pastoralists were not only very, very good at delivering
the vaccine, but that they also knew more about the disease and how to
stop it than many of the experts.
=93We soon discovered that the livestock owners knew more than
anyone=97including government officials, researchers or
veterinarians=97where outbreaks were occurring,=94 Mariner said. =93It was
their expertise about the sizes of cattle herds, their location,
seasonal movement patterns and optimal time for vaccination that made
it possible for us to eradicate rinderpest.=94
Based on their immense expertise about migratory patterns and in
recognizing early signs of infection, the herders were able to
pinpoint, well before scientists ever could, where some of the final
outbreaks were occurring=97often where conventional surveillance
activities had failed to disclose disease. Harnessing this knowledge
of rinderpest through =93participatory surveillance=94 of outbreaks to
CAHW delivery of vaccination proved to be the most successful approach
to monitoring and controlling the disease. It effectively removed the
disease from some of the hardest-to-reach, but also most
disease-ridden, communities.
Applying rinderpest lessons to other diseases
While livestock and those who depend on them for food, transportation
and economic stability are now safe from one major pathogen, they
continue to be plagued by a number of other dangerous and debilitating
diseases=97some as deadly as rinderpest.
The international animal health community is now gearing up to address
the next major constraint to livestock livelihoods in Africa and Asia.
In their analysis, Mariner and colleagues consider how the lessons
learned from battling rinderpest can be applied to protect livestock
from other infectious agents=97particularly peste des petits ruminants
(PPR), also known as =93goat plague.=94 Strategies to address PPR using
the lessons from rinderpest have been developed and action is underway
to mobilize international support for a coordinated program to tackle
PPR. As a next step, ILRI and the Africa Union/Interafrican Bureau for
Animal Resources are planning to host the next meeting of the PPR
Alliance, a partnership of research and development organizations who
prioritize PPR, in Nairobi in early 2013.
A dangerous virus that can destroy whole flocks of sheep and goats,
PPR threatens livestock owners in Africa, Asia and the Middle East, in
particular. As with rinderpest, a sheep or goat infected with PPR will
come down with a high fever and will stop eating, leading to severe
diarrhea and death. Eventually, it will take down the entire herd of
the animals, which are equal to cattle in their importance to the
poor. And controlling PPR is made challenging by the short life span
and heavy trading of sheep and goats=97making it difficult to keep the
disease in check and preventing its spread to new areas.
Nonetheless, the lessons of rinderpest eradication have begun to have
an impact on the toll exacted by goat plague. Participatory
surveillance methods are now applied in many countries, CAHWs are now
frequently involved in vaccination campaigns and ILRI has developed a
temperature-stable vaccine that can be transported to rural farms and
has started to put into place training programs for shepherds and
farmers in Uganda and Sudan to deliver it.
Eventually, these same lessons could be applied to other livestock
diseases such as foot-and-mouth disease=97even some that have recently
jumped to humans, like avian flu. Such =93zoonotic=94 diseases are
responsible for 2.4 billion cases of human illness and 2.2 million
deaths per year, primarily in low- and middle-income countries.
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The International Livestock Research Institute (ILRI) works with
partners worldwide to support the role livestock play in pathways out
of poverty. ILRI research products help people in developing countries
enhance their livestock-dependent livelihoods, health and environments
through better livestock systems, health, productivity and marketing.
ILRI is a member of the CGIAR Consortium of 15 research centres
working for a food-secure future. ILRI has its headquarters in
Nairobi, Kenya, a principal campus in Addis Ababa, Ethiopia, and other
offices in southern and West Africa and South, Southeast and East
Asia.