Tuesday, 9th of October 2007 |
CHILD SURVIVAL UPDATE 33/2007: THREE ON ERADICATION
1) THREE ON ERADICATION
Scott Barrett makes the economic case for disease eradication as
over against long term disease control in this article from the Bulletin of
the World Health Organization. This article is also available at
http://www.who.int/bulletin/volumes/82/9/683.pdf
One point not always mentioned in discussions is the savings to
industrialized countries from eradication. According to Barrett,
"high-income countries typically benefit so much that they will
be willing to finance elimination
in developing countries. Full financing of an eradication
effort by nation-states is not always guaranteed,
but it can be facilitated by a variety of means. Hence, from
the perspective of economics and international
relations, eradication has a number of advantages over
control."
In "Eradication of Infectious Diseases," Isao Arita and colleagues
take a different view of disease eradication. As polio eradication
approaches the finish line, some readers will be skeptical of their
skepticism. The article is also accessible at
http://www.ncbi.nlm.nih.gov/entrez/utils/fref.fcgi?PrId=3155&itool=AbstractPlus-def&uid=14985628&db=pubmed&url=http://www.nih.go.jp/JJID/57/1.html
In the unpublished discussion at the foot of this E-mail, the present
writer looks at proof of concept for disease eradication. The WHA
resolution of 1955, committing WHO and member states to time limited
malaria eradication, rested on an inadequate evidence base, and has biased
subsequent discussions of eradication initiatives. Smallpox, polio and
measles furnish additional lessons learned.
2) MALE CIRCUMCISION IN RWANDA
This self-explanatory account from the semi-official New Times of Rwanda
puts paid to the notion that African traditions preclude the introduction
of male circumcision for HIV prevention.
Since most Rwandese males are uncircumcised, one cannot circumcise the
whole at risk population simultaneously. The government has decided to
start with institutionalized populations. "Mass circumcision would kick off
with the army, police and students from higher institutions of learning."
Good reading.
BD
Proof of concept for four eradication efforts: malaria, smallpox, polio, and measles
Bob Davis, UNICEF/Nairobi
MALARIA
The 1955 decision by WHO's governing body to launch a worldwide war on
malaria was made after stunning victories against malaria in the Balkans,
southern Europe, and Taiwan. The proof of concept was so geographically
narrow as not to demonstrate feasibility in countries and continents with
different economic, political and environmental conditions. In particular,
the colonial regimes of the 1950s were unwilling to make the massive
outlays which could have advanced malaria eradication, along WHO
guidelines, in subsaharan Africa. Also, the planners of 1955 underestimated
the speed with which resistance to insecticides and antimalarials would
compromise prospects of the global programme. No efforts were made to limit
the use of DDT in agriculture, which may have speeded the development of
insecticide resistance in malaria eradication.
In 1969, after stagnation in most of Africa and setbacks in several large
Asian programmes, the World Health Assembly passed a resolution saying
that eradication was not possible except through primary health care. This
was a tacit admission of defeat for what started as a vertical eradication
programme.
SMALLPOX
The series of smallpox eradication resolutions, dating from the 1950s, was
originally based on the assumption that mass vaccination campaigns were
both necessary and sufficient to stop smallpox transmission. Many
industrialized countries stopped smallpox transmission either by universal
vaccination or by mass campaigns, or a combination of the two.
It was only when, during Nigeria's civil war, surveillance and containment
showed the feasibility of a more focal approach, that smallpox eradication
became truly feasible. New emphasis on surveillance as a tool of focal
containment produced dramatic results, first in Nigeria, then in other
endemic countries.
Finally, smallpox eradication was cheap. The total international outlays
were on the order of $125 million, a mere fraction of the figures for other
eradication programmes. A single organization, WHO, took the lead, with
help from CDC, so there were few difficulties delineating tasks among
partners.
POLIO
Industrialized countries eliminated polio through a combination of polio
days and routine vaccination. Latin America showed that mass campaigns
using trivalent oral polio vaccine could stop transmission even when
routine coverage was suboptimal.. Over a period of years, the combination
of routine vaccination and mass campaigns stopped transmission in the
western hemisphere, then, less quickly, in Asia and Africa.
When Type 2 wild poliovirus disappeared, the advantages of monovalent
vaccines became evident. The post-2000 eradication efforts have brought
several issues to the fore: the need to deal with circulating vaccine
derived polio virus, the relative advantages of monovalent over trivalent
vaccine for mass campaigns, and the need for faster outbreak response
through new lab protocols with faster turnaround and immediate outbreak
planning upon lab confirmation of wild poliovirus.
Donor support continued, even during the period 2003-2006, when global
cases stagnated between 1000 and 2000 per year. The current year has seen
striking declines in incidence, both in the four endemic countries and in
importation countries.
MEASLES
Because it is so contagious and travels so well, measles can only be
tackled on a national and continental scale. This has been done
successfully in the region of the Americas, but less so in the rest of the
world. The successes of measles elimination in the western hemisphere have
fueled both the global Measles Partnership, bringing together donors and
other partners in a more coherent way than some previous efforts, and
regional elimination resolutions in 4 out of 6 WHO regions. The future of
measles elimination initiatives is largely a matter of funding. Will the
international community opt for permanent control, or a "short, sharp
shock" approach? There will be little enthusiasm for a two decade effort of
the kind, now coming to a conclusion, against polio.
THE AFRICA FACTOR
In each of these four efforts, Africa has played a pivotal role. In the
case of malaria, the then colonial governments ruling most of Africa failed
to make the political and financial investments needed to launch malaria
eradication along WHO guidelines. Ethiopia, always independent, was an
exception, but even there the application of WHO guidelines did not bring
about malaria elimination. The same decades of the '50s and '60s which saw
progress in South America saw stagnation in most of Africa. The failure of
malaria eradication in Africa and Asia led to the reappraisal of malaria
eradication and to the WHA resolution of 1969, with subsequent
retrenchments and, decades, later, a shift to new technologies and
techniques, notably long life bednets and intermittent presumptive therapy.
In smallpox, Africa was at the origin of the successful modification to the
original strategy, with surveillance and containment developed in the
Biafra war and disseminated to all remaining endemic areas.
In polio, Africa remained a major reservoir of infection through the last
decades of polio eradication, largely because of social, political and
religious factors in Nigeria, the last endemic country on the continent.
The year long suspension of polio vaccination in northern Nigeria
occasioned additional expenditures, in Nigeria and elsewhere, of over $500
million, slowing the global eradication effort.
With measles, southern Africa became the test case for successful
interruption of transmission, and remains so, amid setbacks linked to the
slow progress of measles campaigns in other parts of the continent and to
suboptimal follow-up campaigns in some countries. Among the six WHO
regions, AFRO is one of two which have not opted for a regional elimination
goal for measles.
LESSONS LEARNED
In every case, Africa is the touchstone for proof of concept. Once
eradicability is demonstrated in Africa, worldwide eradicability becomes a
more credible idea, and skepticism is discredited. Underestimating the
African factor, as was done with the WHA malaria eradication of 1955, can
have fatal consequences.
Will rubella eradication move on to the global agenda in this century? This
can happen if and only if African governments take congenital rubella
syndrome and its elimination more seriously than they currently do.
Are three drugs for malaria better than two?
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