Integrated Vector Management - Biological and Environmental Control of Disease Vectors - page 176

and technical resources for vector-borne disease
control from the community level through to the
national level (WHO, 2004a). In 2004, the
World Health Organization (WHO) set out
the Global Strategic Framework for IVM (WHO,
2004a). This document provided guidelines
with the aim to strengthen vector control by
addressing current defi ciencies, and outlined
ways in which the cost ef ectiveness, ecological
soundness, ei cacy and sustainability of vector
control could be improved. IVM was defi ned as 'a
rational decision-making process for the optimal
use of resources for vector control'. WHO
highlighted the fi ve major components of an
IVM strategy: (i) advocacy, social mobilization
and legislation; (ii) collaboration within the
health sector and with other sectors; (iii) an
integrated approach; (iv) evidence-based
decision making; and (v) capacity building
(WHO, 2004a). The emphasis of IVM is on
examining and analysing the local situation and
making decisions at decentralized levels. The
involvement of sectors other than health
authorities is to be encouraged so that all
appropriate vector control tools can be utilized.
If implemented correctly, this approach should
be sustainable, community focused and cost
ef ective.
In essence, IVM is a comprehensive strategy
that integrates available and ef ective resources
(chemical, biological and/or environmental) to
reduce or interrupt transmission of disease. The
knowledge of the impact that biology, ecology
and genetics has on disease transmission,
combined with multiple interventions for vector
control, can lead to more successful and
sustainable disease prevention programmes
than using one type of intervention in isolation.
There are a range of interventions implementing
chemical, biological, or environmental control
tools, but each intervention category has its
disadvantages. Chemicals can pollute the
environment and, importantly, insecticide
resistance has developed to the point where
many chemical-dependent tools are no longer
able to control disease vectors ef ectively (Ranson
et al ., 2011). Biological tools have their own
problems. For example, invertebrate and fi sh
predators must be able to survive in the same
habitat as the target vector (see Howard, Chapter
2, and Chandra et al ., Chapter 3, this volume,
respectively), and entomopathogenic fungi may

not be able to withstand the tropical African
climate (Howard et al ., 2011). Environmental
management is labour intensive and usually
requires regular maintenance (see Ensink et al .,
Chapter 8, this volume), and not all habitats can
be located and treated or removed. One of the
benefi ts of IVM is that it overcomes the
disadvantages of using individual methods
because combinations can be more ef ective
than any tool used in isolation as predicted by
mathematical models (Yakob and Yan, 2009), in
part due to synergistic ef ects (Hancock, 2009).
Empirical evidence agrees with the models; a
systematic review and meta-analysis of 56
publications detailing the results from dengue
control fi eld studies found IVM to be the most
ef ective method of reducing standard
entomological indices when compared to studies
only using chemical, biological or environmental
methods (Erlanger et al ., 2008). A practical
example of improved disease control through
the use of an integrated approach is provided by
a fi eld study in Taiwan (Chen et al ., 1994), which
concluded that such an approach was the best
way to reduce dengue disease transmission.
In 2008, the WHO released a position
statement on IVM (WHO, 2008) where they
reiterated the major attributes of IVM and
highlighted the main advantages of adopting an
IVM strategy. These include the ability to
mitigate the health status changes resulting
from increased urbanization and population
movements, the ability of IVM to sustain the
public-health achievements resulting from
global malaria initiatives, the fact that IVM
allows a reduction in the reliance on chemicals
with the resulting benefi cial ef ects on the
environment and, fi nally, the ability of IVM
strategies to extend the usefulness of insecticides
that are facing growing resistance problems. In
this position statement, WHO called for
countries, international organizations and
donor agencies to accelerate the development of
national IVM strategies to tackle diseases such
as malaria, dengue, fi lariasis and other vector-
borne diseases. In addition to the WHO
documents on IVM, several independent
scientists explored the IVM concept in more
depth (Beier et al ., 2008), outlined a framework
for decision making (van den Berg and Takken,
2007) and discussed how to evaluate IVM (van
den Berg and Takken, 2008).