MALARIA ELIMINATION IN ZANZIBAR - Soper Strategies

INTRODUCTION
BACKGROUND
In October 2007, Bill and Melinda Gates put malaria elimination
and eradication back on the global agenda (Roberts and Enserink,
2007). Their bold statements, together with the impact recently
seen from traditional malaria control interventions (WHO,
2008) have meant that several countries in sub-Saharan Africa
are considering malaria elimination once again. Apart from the
recently published World Health Organization (WHO) guidelines
on malaria elimination (WHO, 2007; WHO EMRO, 2007a)
and prevention of reintroduction (WHO EMRO, 2007b), few
up-to-date reference documents are available to guide countries
in the comprehensive planning for a malaria elimination program.
In most countries, the institutional memory from the Global
Malaria Eradication Program (GMEP) era has been lost. While
one can read old accounts, many critical factors, from the control
environment to the governance structures and health systems in
place, have changed. Moreover, the current (WHO) guidelines set
out a number of contextual prerequisites that effectively exclude
developing countries in sub-Saharan Africa.
Zanzibar is one of the countries in sub-Saharan Africa that
recently expressed its willingness to move from control towards
elimination. Although elimination efforts have twice before failed
in Zanzibar (in the 1960’s under the GMEP and in the 1980’s in
a project funded by the United States Agency for International
Development (USAID), the epidemiological context and the
geographically limited island setting has always been considered
as a model site for elimination (Schwartz et al., 1997; Minjas et
al., 1988). As in most of sub-Saharan Africa, elimination efforts
in Zanzibar failed both as a result of administrative issues and
mosquito resistance to DDT used in indoor residual spraying (IRS),
the main strategy of the GMEP. However, the recent increase
in funding, mainly through the Global Fund to Fight AIDS,
Tuberculosis and Malaria (GFATM) and the U.S. President’s
Malaria Initiative (PMI), coupled with the introduction of highly
effective treatment, long-lasting insecticide-treated bed nets for
prevention, and new insecticides for IRS has again raised the
government’s interests in the possibility of malaria elimination.
RATIONALE AND OBJECTIVES
In Zanzibar, the introduction of Artemisinin-based Combination
Therapy (ACT) for malaria treatment in 2003 has been associated
with a two-fold decrease in malaria prevalence in under-fives by
2005. Another ten-fold decrease was seen between 2005 and 2006
after the introduction of LLINs (Bhattarai et al., 2007). More
recent data further justify Zanzibar’s move toward elimination.
In 2008, more than 70% of under-fives and pregnant women
slept under an insecticide-treated bed net; 96% of houses
were covered with IRS during the last spraying cycle; the slide
positivity rate is below the 5% WHO threshold to move towards
pre-elimination; and the most recent survey revealed only 0.8%
malaria prevalence (ZMCP, 2008).
The Zanzibar Ministry of Health and Social Welfare (MOHSW)
and the ZMCP are now faced with a number of important
strategic questions. Should they seek to completely eliminate
malaria transmission from the islands or maintain it at roughly
current low levels? How should they change the current
intervention approach based on that goal? When can they begin
scaling back interventions without causing a resurgence of
malaria? These are technically complex questions, the answers
to which are further complicated by the dearth of attention to
and research on elimination in recent decades. Given this lack
of information, the MOHSW and ZMCP decided to conduct a
thorough assessment of the feasibility of malaria elimination on
the islands to answer these and other critical strategic questions.
The primary objective of the feasibility assessment exercise was
to provide the MOHSW with as robust as possible evidence
to enable it to make informed decisions about the future of its
malaria program and associated investment in the health system.
A secondary objective was to develop tools and lessons learned to
facilitate similar exercises by other countries considering malaria
elimination.
METHODOLOGY
CONCEPT AND GENERAL FRAMEWORK
To our knowledge, there are no recent examples of country level
feasibility assessments for malaria elimination. In order to develop
a framework for this exercise, historical WHO reports and
guidelines, including the only textbook on malaria eradication
by Emilio Pampana (1969), from the GMEP era were reviewed.
The review revealed that although the WHO encourages
countries to assess the feasibility of malaria elimination, apart
from a list of questions, they don’t provide a framework or
methodology for this exercise (WHO, 2007). Historically,
technical, administrative, and practical feasibility were clearly
defined, but recommendations on assessing feasibility were
ambiguous (Pampana, 1969). Technical feasibility was more or
less assumed and formed, together with the fear for emerging
resistance of the Anopheles mosquito to DDT, the basis for the
GMEP (WHO, 1955). Administrative and practical feasibility,
which included financial feasibility, on the other hand were not
taken for granted, especially in developing countries and were
encouraged to be evaluated by doing a pre-eradication survey
and dealt with during a pre-eradication program (WHO, 1961).
However, pre-eradication surveys were only recommended
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